RU2830492C2 - Light treatment of chromium catalysts and associated catalyst production systems and polymerisation methods - Google Patents

Abstract

FIELD: molding.

SUBSTANCE: invention relates to ethylene copolymers intended for molding industrial articles. Disclosed is an ethylene copolymer for molding industrial articles, having a ratio M_w/M_n in range of 50 to 90, ratio M_z/M_w in range from 4 to 10; and parameter CY-a in range from 0.2 to 0.4, found on the basis of rheological measurements carried out at 190 °C, and from 0.5 to 4 long-chain branches per million of all carbon atoms.

EFFECT: said copolymer is suitable for producing molded articles.

9 cl, 4 dwg, 5 tbl, 52 ex

Description

LINK TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent Application No. 62/732,020, filed September 17, 2018, the disclosure of which is incorporated herein by reference in its entirety.

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

The present invention relates generally to chromium catalysts, methods for producing chromium catalysts, methods for using chromium catalysts to polymerize olefins, polymer resins produced using such chromium catalysts, and articles made using said polymer resins. More particularly, the present invention relates to irradiating a supported hexavalent chromium catalyst with UV-visible light and related catalyst production systems, polymerization reactor systems, and olefin polymerization methods.

LEVEL OF TECHNOLOGY

Chromium catalysts are among the most common catalysts used in olefin polymerization. Supported chromium catalysts are often prepared by impregnating chromium onto a solid support, such as a solid oxide, followed by a calcination step. Generally, the calcination is carried out in an oxidizing atmosphere so that the chromium compounds in the supported chromium catalyst can be converted to hexavalent chromium.

There are methods for reducing supported chromium catalysts to lower oxidation states such as Cr(II), Cr(III), Cr(IV) and Cr(V), but such methods often require high temperatures, reduce catalytic activity and result in polymers with low potential melt flow index. It would be useful to obtain reduced chromium catalysts that do not suffer from these disadvantages. Accordingly, the present invention is generally directed to solving such problems.

ESSENCE OF THE INVENTION

This summary of the present invention is provided to introduce a selection of concepts in a simplified form that are further presented below in the detailed description. It is intended that this summary is not intended to identify required or key distinguishing features of the claimed subject matter. It is also intended that this summary does not limit the scope of the claimed subject matter.

One aspect of the present invention relates to catalyst production systems that may include (a) a catalyst production vessel configured to irradiate a chromium catalyst slurry on a support in a diluent using a light beam with a wavelength in the UV-visible region of the spectrum, (b) a catalyst inlet configured to introduce the chromium catalyst slurry on the support into the catalyst production vessel, wherein at least a portion of the chromium is in a hexavalent oxidation state, and (c) a reduced catalyst outlet configured to remove the reduced chromium catalyst slurry from the catalyst production vessel. The present document also describes polymerization reactor systems that include catalyst production systems.

According to another aspect of the present invention, methods for reducing a chromium catalyst for the polymerization of olefins are provided. A typical method may include irradiating a reducing agent and a supported chromium catalyst containing chromium in a hexavalent oxidation state with a light beam with a wavelength in the UV-visible region of the spectrum to reduce at least a portion of the supported chromium catalyst to obtain a reduced chromium catalyst.

According to another aspect of the present invention, methods of polymerizing olefins are provided, wherein such methods may comprise (I) irradiating a reducing agent and a supported chromium catalyst comprising chromium in a hexavalent oxidation state with a light beam of a wavelength in the UV-visible region of the spectrum to convert at least a portion of the supported chromium catalyst to produce a reduced chromium catalyst and (II) contacting the reduced chromium catalyst and an optional cocatalyst with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization reaction conditions to produce an olefin polymer.

Reduced chromium catalysts and olefin polymers obtained by using the corresponding methods and processes are also included in the present invention. Unexpectedly and advantageously, reduced chromium catalysts can have higher catalytic activity and/or productivity compared to chromium catalysts obtained without the irradiation step. Moreover, the olefin polymers described herein are often characterized by higher melt flow properties and a narrower molecular weight distribution than olefin polymers obtained by methods using reduced chromium catalysts obtained without the irradiation step.

The present document also provides ethylene-based polymers having an unexpected and useful combination of properties. According to one aspect of the present invention, an ethylene polymer can be characterized by an Mw/Mn ratio in the range of from about 30 to about 110, an Mz/Mw ratio in the range of from about 4 to about 10, and a CY-a parameter in the range of from about 0.2 to about 0.4. According to another aspect of the present invention, an ethylene polymer can be characterized by an Mw/Mn ratio in the range of from about 6 to about 15, an Mz/Mw ratio in the range of from about 30 to about 70, and a melt flow index in the range of from about 0.5 to about 10 g/10 min.

Both the above summary of the invention and the following detailed description provide examples, and the descriptions themselves are illustrative only. Accordingly, the above summary and the following detailed description should not be considered limiting. In addition, features or variations in addition to those set forth herein may be proposed. For example, some aspects may relate to various combinations and subcombinations of the features discussed in the detailed description.

BRIEF DESCRIPTION OF GRAPHIC MATERIALS

Fig. 1 is a block diagram of a catalyst production system and a polymerization reactor system consistent with aspects of the present invention.

Fig. 2 shows a graph of the range of wavelengths emitted by red, blue and violet LEDs used to irradiate the chromium catalyst on the substrate obtained according to Example 27.

Fig. 3 shows a graph of the IR reflectivity of the Cr/silica catalyst according to Example 28 calcined at 650°C.

Fig. 4 shows a graph of the molecular weight distributions of the polymers obtained according to Examples 36, 40 and 42.

DEFINITIONS

For a clearer understanding of the terms used herein, the following definitions are provided. Unless otherwise specified, the following definitions apply to the present specification. Whenever a term is used in the specification that is not specifically defined herein, the definition given in the IUPAC Compendium of Chemical Terminology, ^2nd Ed (1997) may be used, provided that such definition does not conflict with any other description or definition used herein or render undefined or invalid any claim to which the definition relates. To the extent that any definition or application given in any document incorporated by reference herein conflicts with a definition or application given herein, the definition or application given herein shall control.

In this document, the features of the subject invention may be described in such a way that different features may be combined within specific aspects. For each and every aspect and/or feature described herein, all combinations that do not adversely affect the systems, compositions, processes and/or methods described herein are contemplated, with or without a detailed description of the specific combination. Furthermore, unless explicitly stated otherwise, any aspect and/or feature described herein may be combined to describe systems, compositions, processes and/or methods according to the present invention that do not conflict with the present invention.

Although systems, compositions, processes and methods are described herein in terms of “comprising” various components or steps, said systems, compositions, processes and methods may also “consist essentially of” or “consist of” the various components or steps, unless otherwise specified.

Singular terms are intended to include plural alternatives, such as at least one. For example, a description of a "diluent" or "reducing agent" is intended to include a single diluent or reducing agent or mixtures or combinations of more than one diluent or reducing agent, unless otherwise specified.

In general, groups of elements are listed using the numbering scheme given in the version of the periodic table of the elements published in Chemical and Engineering News , 63(5), 27, 1985. In some cases, a group of elements may be listed using the common name for that group; for example, the alkali metals for Group 1 elements, the alkaline earth metals for Group 2 elements, the transition metals for Groups 3–12 elements, and the halogens or halides for Group 17 elements.

The term "hydrocarbon" as used in the present specification and claims refers to a compound containing only carbon and hydrogen, regardless of whether the compound is saturated or unsaturated. Other identifiers may be used to indicate the presence of specific groups in a hydrocarbon (e.g., a halogenated hydrocarbon indicates the presence of one or more halogen atoms replacing an equivalent number of hydrogen atoms in the hydrocarbon). As used herein, the term "hydrocarbyl group" is defined as a monovalent group formed by removing a hydrogen atom from a hydrocarbon (i.e., a group containing only carbon and hydrogen). Non-limiting examples of hydrocarbyl groups include, among other groups, alkyl, alkenyl, aryl, and aralkyl groups.

For any particular compound or group described herein, any name or structure given is intended to include all structural isomers, conformational isomers, regioisomers, stereoisomers, and mixtures thereof that may result from the particular set of substituents, unless otherwise specified. The name or structure also includes all enantiomers, diastereomers, and other optical isomers (if any), whether in enantiomeric or racemic forms, as well as mixtures of stereoisomers, as would be understood by one of skill in the art, unless otherwise specified. For example, a general reference to hexene (or hexenes) includes all linear or branched, acyclic or cyclic hydrocarbon compounds containing six carbon atoms and 1 carbon-carbon double bond; pentane includes n-pentane, 2-methylbutane, and 2,2-dimethylpropane; and the butyl group includes n-butyl group, sec-butyl group, isobutyl group and tert-butyl group.

Unless otherwise indicated, the term "substituted" when used to describe a group, such as when referring to a substituted analog of a particular group, is intended to describe any non-hydrogen moiety that formally replaces a hydrogen in such group, and is intended to be non-limiting. Additionally, unless otherwise indicated, a group or groups may also be referred to herein as "unsubstituted" or by equivalent terms such as "not substituted," which term refers to the parent group in which the non-hydrogen moiety does not replace a hydrogen atom within such group. Additionally, unless otherwise indicated, the term "substituted" is intended to be non-limiting and includes inorganic substituents or organic substituents, as understood by one skilled in the art.

As used herein, the term "polymer" generally includes olefin homopolymers, copolymers, terpolymers, and the like, as well as alloys and blends thereof. The term "polymer" also includes impact copolymers, block copolymers, graft copolymers, random copolymers, and alternating copolymers. A copolymer can be prepared from an olefin monomer and one olefin comonomer, while a terpolymer can be prepared from an olefin monomer and two olefin comonomers. Accordingly, "polymer" includes copolymers and terpolymers. Likewise, the scope of the term "polymerization" includes homopolymerization, copolymerization, and terpolymerization. Accordingly, an ethylene polymer will include ethylene homopolymers, ethylene copolymers (e.g., ethylene/α-olefin copolymers), ethylene terpolymers, and the like, as well as combinations or mixtures thereof. Thus, the ethylene polymer includes polymers often referred to in the art as LLDPE (linear low density polyethylene) and HDPE (high density polyethylene). For example, an ethylene copolymer can be prepared from ethylene and a comonomer such as 1-butene, 1-hexene, or 1-octene. If the monomer and comonomer were ethylene and 1-hexene, respectively, the resulting polymer could be classified as an ethylene/1-hexene copolymer. The term "polymer" also includes all possible geometric configurations, if present and unless otherwise specified, wherein such configurations may include isotactic, syndiotactic, and random symmetries.

As used herein, ethylene polymers also include ethylene-based polymers containing non-traditional end groups or chain ends. Traditional end groups or chain ends include those groups that are typically formed (e.g., saturated methyl chain ends, vinyl or vinylidene chain ends) by polymerizing ethylene, either alone or with alpha-olefin comonomers such as 1-butene, 1-hexene and 1-octene. Non-traditional end groups or chain ends included in the present invention may include various branched alkane, cyclic alkane, aromatic and halogenated hydrocarbon groups.

As used herein, the term "contacting" is used to describe systems, compositions, processes, and methods in which components are combined or reacted in any order, in any manner, and for any period of time, unless otherwise specified. For example, components can be contacted by combining or mixing using any suitable technology.

A "soluble" substance means that the substance dissolves at standard temperature (25 ^o C) and pressure (1 atm (approximately 101 kPa)), without visible precipitation of the substance in the solvent (e.g., water or a hydrocarbon solvent). Similarly, a "solution" means no visible precipitation at standard temperature and pressure.

Various ranges of numerical values are provided herein. When a range of any type is provided or claimed herein, the intent is to describe or claim individually each possible number that could reasonably be included within such range, including the endpoints of the range, as well as any subranges and combinations of subranges included therein, unless otherwise stated. As a typical example, in some aspects, this application states that the total pore volume of a chromium catalyst can range from about 0.9 to about 3 ml/g. When stating that the chromium catalyst can have a total pore volume in the range of from about 0.9 to about 3 ml/g, the intent is to indicate that the total pore volume can have any value within the stated range and, for example, can be about 0.9, about 1.0, about 1.1, about 1.2, about 1.3, about 1.4, about 1.5, about 1.6, about 1.7, about 1.8, about 1.9, about 2.0, about 2.1, about 2.2, about 2.3, about 2.4, about 2.5, about 2.6, about 2.7, about 2.8, about 2.9, or about 3 ml/g. In addition, the total pore volume may be in any range from about 0.9 to about 3 ml/g (e.g., the total pore volume may be from about 1.2 to about 2.5 ml/g), wherein the stated range also includes any combination of ranges from about 0.9 to about 3 ml/g. In addition, in all cases where “about” a particular value is stated, such value is also described per se. Thus, a statement that the pore volume is from about 0.9 to about 3 ml/g also indicates a pore volume range from 0.9 to 3 ml/g (e.g., from 1.2 to 2.5 ml/g), wherein such range also includes any combination of ranges from 0.9 to 3 ml/g. Likewise, all other ranges described herein should be interpreted by analogy with the given example.

The term "about" means that amounts, sizes, compositions, parameters and other quantities and characteristics are not and do not have to be exact, but may have an approximate value, including more or less, as necessary, reflecting tolerances, conversion factors, rounding, measurement errors and the like, as well as other factors known to those skilled in the art. In general, a quantity, size, composition, parameter or other quantity or characteristic is "about" or "approximate", regardless of whether it is explicitly stated or not. The term "about" also includes amounts that vary due to different equilibrium conditions for a composition obtained from a particular starting mixture. Regardless of whether such a value is modified by the term "about" or not, the claims include equivalents of such quantities. The term "about" can mean within 10% of the recited numerical value, preferably within 5% of the recited numerical value.

Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, representative methods and materials are described herein.

All publications and patents mentioned in this document are herein incorporated by reference for the purpose of describing and disclosing, for example, concepts and methodologies described in the publications that may be used in conjunction with the invention described herein.

DETAILED DESCRIPTION OF THE INVENTION

In general, the present invention relates to methods for reducing chromium catalysts by irradiating catalysts on a hexavalent chromium-based support with light in the presence of a reducing agent. Also provided are catalyst preparation systems for reducing catalysts on a hexavalent chromium-based support and methods for polymerizing olefins using reduced chromium catalysts.

METHODS OF RESTORING CHROMIUM CATALYSTS

Methods for reducing chromium catalysts may include irradiating a reducing agent and a supported chromium catalyst containing chromium in a hexavalent oxidation state with a light beam of wavelength in the UV-visible region of the spectrum to reduce at least a portion of the supported chromium catalyst to produce a reduced chromium catalyst. The reduced chromium catalyst has a lower average oxidation state than the supported chromium catalyst. Reduced chromium catalysts produced by any of the methods described herein are also included in the present invention.

In general, the disclosed methods can be used to reduce any chromium catalyst and are not limited to reducing any particular type of supported chromium catalyst. Thus, supported chromium catalysts contemplated herein include catalysts prepared by contacting a solid oxide with a chromium-containing compound - typical and non-limiting examples of chromium compounds include chromium(III) acetate, basic chromium(III) acetate, chromium(III) acetylacetonate, _Cr2 ( _SO4 ) ₃ , Cr( _NO3 ) ₃ , and _CrO3 - and calcining in an oxidizing atmosphere to produce a supported chromium catalyst. In such aspects, the chromium impregnation can be performed during or before the calcination step, which can be performed at various temperatures and for various periods of time, wherein said parameters can generally be selected so as to convert all or part of the chromium to hexavalent chromium. The irradiation methods described herein can include reducing at least a portion of the hexavalent chromium compounds to a lower oxidation state - for example, to produce Cr(II), Cr(III), Cr(IV), and/or Cr(V) compounds, any of which can be catalytically active as an olefin polymerization catalyst - wherein the reduced catalyst can be used to produce polymers with unexpected properties.

Any suitable chromium-containing compound (or chromium precursor) can be used as the chromium component for producing the supported chromium catalyst. Illustrative and non-limiting examples of chromium(II) compounds can include chromium(II) acetate, chromium(II) chloride, chromium(II) bromide, chromium(II) iodide, chromium(II) sulfate, and the like, and combinations thereof. Similarly, illustrative and non-limiting examples of chromium(III) compounds can include chromium(III) carboxylate, chromium(III) naphthenate, chromium(III) halide, chromium(III) sulfate, chromium(III) nitrate, chromium(III) dionate, and the like, and combinations thereof. In some aspects, the chromium-containing compound may include chromium(III) acetate, chromium(III) acetylacetonate, chromium(III) chloride, chromium(III) bromide, chromium(III) sulfate, chromium(III) nitrate, etc., and combinations thereof.

Although not required, it may be advantageous for the chromium-containing compound to be soluble in the hydrocarbon solvent during catalyst preparation. In such cases, the chromium-containing compound may include tertiary butyl chromate, a chromium(0) diarene compound, bis-cyclopentadienyl chromium(II), chromium(III) acetylacetonate, chromium acetate, and the like, or any combination thereof. Similarly, and not necessarily, it may be advantageous for the chromium-containing compound to be soluble in water during catalyst preparation. In such cases, the chromium-containing compound may include chromium trioxide, chromium acetate, chromium nitrate, and the like, or any combination thereof.

In addition, any suitable solid oxide can be used as a solid support for the supported chromium catalyst. In general, the solid oxide can contain oxygen and one or more elements selected from Group 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 of the periodic table of the elements, or can contain oxygen and one or more elements selected from the lanthanides or actinides (see: Hawley's Condensed Chemical Dictionary, 11^th Ed., John Wiley & Sons, 1995; Cotton, F. A., Wilkinson, G., Murillo, C. A., and Bochmann, M., Advanced Inorganic Chemistry, 6^thEd., Wiley-Interscience, 1999). For example, the solid oxide may comprise oxygen and an element or elements selected from Al, B, Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, La, Mn, Mo, Ni, Sb, Si, Sn, Sr, Th, Ti, V, W, P, Y, Zn, and Zr. Illustrative examples of solid oxide materials or compounds that can be used as a solid support may include, but are not limited to, Al₂O₃, B₂O₃, BeO, Bi₂O₃, CdO, Co₃O₄, Cr₂O₃, CuO, Fe₂O₃, Ga₂O₃, La₂O₃, Mn₂O₃, MoO₃, NiO, P₂O₅, Sb₂O₅, SiO₂, SnO₂, SrO, ThO₂, TiO_2,V₂O₅, WO₃, Y₂O₃, ZnO, ZrO₂etc., including their mixed oxides and their combinations.

The solid oxide may include oxide materials such as silica, their "mixed oxide" compounds such as silica-titania, and combinations or mixtures of more than one solid oxide material. Mixed oxides such as silica-titania may be one or more chemical phases containing more than one metal combined with oxygen to form a solid oxide. Examples of mixed oxides that can be used as the solid oxide include, but are not limited to, silica-alumina, silica-coated alumina, silica-titania, silica-zirconia, alumina-titanium dioxide, alumina-zirconia, zinc aluminate, alumina-boron oxide, silica-boron oxide, aluminum phosphate, aluminophosphate, aluminophosphate-silicon dioxide, titanium dioxide-zirconia, and the like, or a combination thereof. In some aspects, the solid support may comprise silica, silica-alumina, silica-coated alumina, silica-titanium dioxide, silica-titanium dioxide-magnesium oxide, silica-zirconia, silica-magnesium oxide, silica-boron oxide, aluminophosphate-silica, and the like, or any combination thereof. Included in the present invention are silica-coated aluminas; such oxide materials are described, for example, in U.S. Patent No. 7,884,163, the disclosure of which is incorporated herein by reference in its entirety.

The percentage of each oxide in the mixed oxide may vary depending on the respective oxide materials. For example, the aluminum oxide content of silica-alumina is typically 5% by weight to 95% by weight. According to one aspect, the aluminum oxide content of silica-alumina may be 5% by weight to 50% by weight or 8% by weight to 30% by weight. According to another aspect, silica-alumina compounds with a high aluminum oxide content may be used, wherein the aluminum oxide content of such silica-alumina materials is typically 60% by weight to 90% by weight or 65% by weight to 80% by weight.

According to one aspect, the solid oxide can comprise silica-alumina, silica-coated alumina, silica-titanium dioxide, silica-zirconia, alumina-titanium dioxide, alumina-zirconia, zinc aluminate, alumina-boron oxide, silica-boron oxide, aluminum phosphate, aluminophosphate, aluminophosphate-silicon dioxide, titanium dioxide-zirconia, or a combination thereof; alternatively silica-alumina; alternatively silica-titanium dioxide; alternatively silica-zirconia; alternatively alumina-titanium dioxide; alternatively alumina-zirconia; alternatively zinc aluminate; alternatively alumina-boron oxide; alternatively, silica-boron oxide; alternatively aluminum phosphate; alternatively, aluminophosphate; alternatively, aluminophosphate-silicon dioxide; or, alternatively, titanium dioxide-zirconium dioxide.

According to another aspect, the solid oxide may comprise silica, alumina, titanium dioxide, zirconium dioxide, magnesium oxide, boron oxide, zinc oxide, a mixed oxide thereof, or any mixture thereof. According to yet another aspect, the solid support may comprise silica, alumina, titanium dioxide, or a combination thereof; alternatively silica; alternatively aluminum oxide; alternatively titanium dioxide; alternatively zirconium dioxide; alternatively magnesium oxide; alternatively boron oxide; or, alternatively, zinc oxide. According to another aspect, the solid oxide may include silica, alumina, silica-alumina, silica-coated alumina, aluminum phosphate, aluminophosphate, heteropolytungstate, titanium dioxide, zirconia, magnesium oxide, boron oxide, zinc oxide, silica-titanium dioxide, silica-zirconia, aluminum oxide-titanium dioxide, aluminum oxide-zirconia, zinc aluminate, aluminum oxide-boron oxide, silica-boron oxide, aluminophosphate-silicon dioxide, titanium dioxide-zirconia, and the like, or any combination thereof.

The irradiation reduction methods described herein may further comprise a calcination step to produce a supported chromium catalyst comprising chromium in a hexavalent oxidation state. The calcination step may be carried out at various temperatures and for various periods of time, which are generally selected to convert all or part of the chromium to hexavalent chromium. Often, calcination is carried out in an oxidizing atmosphere, but this is not a requirement.

For example, the calcining step can be carried out at a maximum temperature in the range of from about 300°C to about 1000°C; alternatively from about 500°C to about 900°C; alternatively, from about 600°C to about 871°C; alternatively, from about 550°C to about 870°C; alternatively, from about 700°C to about 850°C; alternatively, from about 725°C to about 900°C; alternatively, from about 725°C to about 871°C; alternatively, from about 725°C to about 850°C; alternatively, from about 750°C to about 871°C; or, alternatively, from about 750°C to about 850°C.

The duration of the calcination step is not limited to any particular period of time. Therefore, such a calcination step can be carried out, for example, for a period of time of from 1 minute to 12-24 hours or more. According to some aspects, the calcination step can be carried out for a period of time of from about 1 minute to about 24 hours, from about 1 hour to about 12 hours, or from about 30 minutes to about 8 hours. A suitable calcination time can depend, for example, on the initial/maximum temperature, among other variables.

Without limitation, the supported chromium catalyst may often comprise chromium/silica, chromium/silica-titanium dioxide, chromium/silica-titanium dioxide-magnesium oxide, chromium/silica-alumina, chromium/alumina with a silica coating, chromium/aluminophosphate, etc., or any combination thereof. According to one aspect, the supported chromium catalyst may comprise chromium/silica, while according to another aspect, the supported chromium catalyst may comprise chromium/silica-titanium dioxide. According to another aspect, the supported chromium catalyst may comprise chromium/silica-titanium dioxide-magnesium oxide; alternatively chromium/silica-alumina; alternatively chromium/alumina with a silica coating; or alternatively chromium/aluminophosphate.

The present document also discloses suitable modifications made to the supported chromium catalyst, which may include treatment with an electron-withdrawing anion and/or a metal compound. In addition, the supported chromium compound may be modified at any time during or after its preparation. For example, in some aspects, the solid support may be modified prior to impregnation with the chromium compound and/or the calcination step. In other aspects, the supported chromium compound may be subjected to suitable modifications after the calcination step. In some aspects, the modifications may include supported chromium catalysts or components thereof that have been fluorinated, chlorinated, brominated, sulfated, or phosphated, and/or supported chromium catalysts that have been impregnated with metal ions (e.g., zinc, nickel, vanadium, titanium (titaniumized), silver, copper, gallium, tin, tungsten, molybdenum, zirconium, etc., or combinations thereof).

The supported chromium catalysts treated with light as described herein and the resulting reduced chromium catalysts may have any suitable pore volume, surface area, and particle size. According to some aspects, the supported chromium catalyst (or reduced chromium catalyst) may have a pore volume (total pore volume) in the range of from about 0.5 to about 5 ml/g, from about 1 to about 5 ml/g, from about 0.9 to about 3 ml/g, or from about 1.2 to about 2.5 ml/g. The surface area of the catalyst is not limited to any particular range, and in some aspects, the BET surface area of the supported chromium catalyst (or reduced chromium catalyst) can be from about 100 to about 1000 ^m2 /g, from about ²⁰⁰ to about 700 m2/g, from about 100 to about 600 ^m2 /g, from about 250 to about 600 ^m2 /g, from about 250 to about 550 ^m2 /g, or from about 275 to about 525 ^m2 /g. Illustrative and non-limiting ranges of the average particle size ( _d50 ) of the supported chromium catalyst (or reduced chromium catalyst) can include ranges of from about 10 to about 500 microns, from about 25 to about 250 microns, from about 40 to about 160 microns, or from about 40 to about 120 microns. BET surface areas are determined using the BET nitrogen adsorption method described in Brunauer et al., J. Am. Chem. Soc. , 60, 309 (1938). Total pore volume is determined according to Halsey, G. D., J. Chem. Phys. (1948), 16, pp. 931. The particle size d50, or median or average particle size, refers to the particle size such that 50% of the particles in a sample are smaller in size and 50% of the particles in a sample are larger in size, the said size being determined by laser diffraction according to ISO 13320.

The amount of chromium in the supported chromium catalyst (or reduced chromium catalyst) is not particularly limited. However, in general, the amount of chromium in the supported chromium catalyst (or reduced chromium catalyst) may be from about 0.01 to about 20 wt %; alternatively from about 0.1 to about 15 wt %; alternatively from about 0.1 to about 10 wt %; alternatively from about 0.2 to about 5 wt %; alternatively from about 0.2 to about 2.5 wt %; alternatively from about 0.5 to about 10 wt %; or alternatively from about 1 to about 6 wt %. The weight percentages given are based on the amount of chromium relative to the total weight of the respective catalyst.

Similarly, prior to the reduction treatment, the supported chromium catalyst may comprise any suitable amount of chromium in its hexavalent state relative to the total amount of chromium in the supported chromium catalyst. According to some aspects, prior to irradiation, the proportion of chromium in the supported chromium catalyst in the hexavalent oxidized state may be at least about 10 wt. %, at least about 20 wt. %, at least about 40 wt. %, at least about 60 wt. %, at least about 80 wt. %, at least about 90 wt. %, at least about 95 wt. %, or at least about 99 wt.

Thus, in some aspects, prior to the reduction treatment, the amount of chromium (VI) in the supported chromium catalyst may be from about 0.01 to about 20 wt. %; alternatively from about 0.1 to about 15 wt. %; alternatively from about 0.1 to about 10 wt. %; alternatively from about 0.2 to about 5 wt. %; alternatively from about 0.2 to about 2.5 wt. %; alternatively from about 0.5 to about 10 wt. %; or alternatively from about 1 to about 6 wt. % The weight percentages given are based on the amount of chromium (VI) relative to the total weight of the supported chromium catalyst.

In general, the irradiating step can be carried out under any conditions sufficient to irradiate the reducing agent and the supported hexavalent chromium catalyst with a light beam and to produce a reduced chromium catalyst (having a lower oxidation state). For example, the relative amount (or concentration) of the reducing agent to the amount of chromium (in the supported chromium catalyst) can change the efficiency of the reduction process. According to some aspects, the molar ratio of reducing agent to chromium (in the supported chromium catalyst) can be at least about 0.25:1, at least about 0.5:1, at least about 1:1, at least about 10:1, at least about 100:1, at least about 1000:1, or at least about 10000:1. Thus, a large excess of reducing agent can be used, and there is no particular limitation on the maximum amount of reducing agent.

Any reducing agents and/or diluents used in the irradiation methods described herein can be selected based on their utility in subsequent olefin polymerization reactions. In one aspect, the reducing agent and the supported chromium catalyst are irradiated at any suitable pressure, wherein the reducing agent is a diluent (or support) for the solid catalyst. It is obvious that under such conditions there is a large excess of reducing agent. In another aspect, a mixture of reducing agent and supported chromium catalyst in a diluent is irradiated at any suitable pressure. In such cases, the reducing agent can be present in much smaller amounts. Thus, the reducing agent can be separated from the diluent, or the reducing agent can be a diluent. In any case, the diluent can be selected based on its utility and utility in any of the olefin polymerization methods described herein. Accordingly, suitable diluents may include certain olefin monomers and comonomers and/or hydrocarbon solvents that are liquid under conditions suitable for the reduction by irradiation and/or for the subsequent polymerization of olefins. Non-limiting examples of suitable hydrocarbon diluents that may be suitable as reducing agents may include propane, isobutane, n-butane, n-pentane, isopentane, neopentane, n-hexane, heptane, octane, cyclohexane, cycloheptane, methylcyclohexane, methylcycloheptane, adamantane, decalin, ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, benzene, toluene, cyclohexene, xylene, ethylbenzene, and the like, or combinations thereof.

The temperature and pressure in the irradiation step may be such that the reducing agent and/or diluent remains a liquid throughout the reduction process of the chromium catalyst. It has been advantageously discovered that the irradiation steps described herein can reduce chromium compounds on a support at temperatures lower than those typically required to reduce hexavalent chromium compounds using heat rather than light. In some aspects, the irradiation step can be conducted at a temperature of less than about 200 °C, less than about 100 °C, less than about 150 °C, less than about 40 °C, from about 0 °C to about 200 °C, from about 0 °C to about 100 °C, or from about 10 °C to about 40 °C, and such irradiation step can produce a reduced chromium catalyst with excellent properties for subsequent olefin polymerization.

In general, reducing agents suitable for use in the present invention may be any reducing agent capable of reducing at least a portion of a chromium compound on a substrate when irradiated with light, as described herein. In one aspect, the reducing agent may be present in a liquid phase, while in another aspect, the reducing agent may be present in a gas phase. Reducing agents contemplated herein (one or more than one in combination) may include any compound containing a CH and/or HH (H ₂ ) bond. In certain aspects, the reducing agent may contain one or more C-C bonds of any order (e.g., single bond, double bond, triple bond), such that almost any saturated or unsaturated hydrocarbon compound containing exclusively CH and C-C bond(s) may be suitable as a reducing agent for use in the methods, processes, and systems provided herein. In certain aspects, a reducing agent can comprise a C1 _{- C36} hydrocarbon, a _C1 - _C18 hydrocarbon, a _C1 - _C12 hydrocarbon, and/or a _C1 - _C8 hydrocarbon. Additionally, reducing agents discussed herein can comprise a substituted and/or unsubstituted hydrocarbon compound. In one aspect, a reducing agent can comprise an alkane, an olefin, an aromatic compound, or any combination thereof (e.g., a _C1 - _C36 alkane, olefin, and/or aromatic compound (up to 36 carbon atoms); a _C1 - _C18 alkane, olefin, and/or aromatic compound (up to 18 carbon atoms); a _C1 - _C12 alkane, olefin, and/or aromatic compound (up to 12 carbon atoms); or a _C1 - _C8 alkane, olefin, and/or aromatic compound (up to 8 carbon atoms)). The alkane may be a linear alkane, a branched alkane or a cyclic alkane. According to another aspect, the reducing agent may include ethylene, 1-butene, 1-hexene, 1-octene, methane, ethane, propane, isobutane, n-pentane, isopentane, n-hexane, tetrafluoroethane, cyclohexane, adamantane, decalin, benzene, toluene and the like or any combination thereof. According to another aspect, the reducing agent may include a halogenated hydrocarbon (halogenated alkane, halogenated aromatic compound) in which one or more halogen atoms replace an equivalent number of hydrogen atoms in the hydrocarbon, provided that the compound contains a CH bond.

The irradiation step can be further characterized by the amount of time that the reducing agent and the chromium catalyst on the support are exposed to the light beam, such as the exposure time. Without being bound by theory, it is believed that the exposure to the light beam in the presence of the reducing agent is responsible for the reduction of the chromium catalyst, and accordingly, it follows that the exposure time should be sufficient to allow such a transformation to occur, regardless of whether this transformation occurs very quickly or very slowly. Thus, according to certain aspects, the exposure time can be from about 15 seconds to about 10 hours, from about 1 minute to about 6 hours, from about 5 minutes to about 1 hour, from about 10 minutes to about 2 hours, from about 1 minute to about 1 hour, or from about 1 minute to about 15 minutes. One skilled in the art will understand that the exposure time can vary depending on the intensity of the light beam.

However, in the examples below, it has been surprisingly found that limiting the exposure time can be advantageous and can provide reduced chromium catalysts with increased catalytic activity and provide olefin polymers with improved melt flow potential compared to chromium catalysts that have been exposed for longer periods. In some aspects, the exposure time can be less than about 1 minute, less than about 5 minutes, less than about 10 minutes, less than about 15 minutes, less than about 30 minutes, less than about 1 hour, less than about 2 hours, or less than about 4 hours.

In the proposed methods, irradiating a sample of a chromium catalyst on a support with a light beam in the UV-visible region of the spectrum in the presence of a reducing agent results in obtaining a chromium catalyst with a reduced degree of oxidation. A wide range of wavelengths, light sources and intensities can be used, provided that such wavelengths, light sources and intensities are sufficient to reduce at least a portion of the hexavalent chromium compounds present in the chromium catalyst on the support. According to certain aspects, for example, the light can be obtained from any suitable source, such as sunlight, fluorescent white light, an LED diode and/or a UV lamp. To improve the efficiency of irradiation, the distance from sources other than sunlight can be varied, if necessary (e.g., minimized).

The wavelength of the light can be any in the UV-visible spectrum region. According to some aspects, the wavelength of the light beam can be one wavelength or more than one wavelength, for example, a range of wavelengths. For example, the wavelength of the light beam can be a range of wavelengths including at least 25 nm, at least 50 nm, at least 100 nm, at least 200 nm or at least 300 nm. According to one aspect, the wavelength of the light beam can include one wavelength or a range of wavelengths in the UV spectrum region, in the visible spectrum region (from 380 nm to 780 nm) or in both spectrum regions. According to another aspect, the wavelength of the light beam can include one wavelength or a range of wavelengths from 200 nm to 750 nm. However, according to another aspect, the wavelength of the light beam may include one wavelength or a range of wavelengths from 300 to 750 nm, from 350 nm to 650 nm, from 300 nm to 600 nm, from 300 nm to 500 nm or from 300 nm to 400 nm. According to other aspects, the wavelength of the light beam may include one wavelength or a range of wavelengths below 600 nm, below 525 nm or below 500 nm; additionally or alternatively, above 350 nm, above 400 nm or above 450 nm.

The light beam in the irradiation step can also be characterized by intensity (e.g., the total amount of light emitted from the source). According to certain aspects, the intensity of the light beam can be at least about 500 lumens, at least about 1000 lumens, at least about 2000 lumens, at least about 5000 lumens, at least about 10000 lumens, at least about 20000 lumens, at least about 50000 lumens, or at least about 100000 lumens. Thus, there may be no upper limit for the intensity of the light source. Alternatively, the intensity of the light beam can be from about 50 to about 50000 lumens, from about 50 to about 10000 lumens, from about 100 to about 5000 lumens, or from about 500 to about 2000 lumens. In addition, the light beam can be characterized by the amount of light reaching the reducing agent and the chromium catalyst on the substrate, i.e., the flux. According to certain aspects, the reducing agent and the chromium catalyst on the substrate containing chromium in a hexavalent oxidation state can be irradiated using at least about 100 lux, at least about 500 lux, at least about 1000 lux, at least about 2000 lux, at least about 5000 lux, at least about 10000 lux, at least about 20000 lux, at least about 100000 lux, or in the range from about 10000 to about 1000000 lux, from about 50000 to about 500000 lux, or from about 50000 to about 200000 lux. Additionally or alternatively, according to certain aspects, the reducing agent and the supported chromium catalyst comprising chromium in a hexavalent oxidation state can be irradiated with a light beam of at least about 50 W, at least about 100 W, at least about 200 W, at least about 500 W, at least about 1000 W, or at least about 2000 W.

The effectiveness of the irradiation reduction methods provided herein can be characterized by the chemical composition of the reduced chromium catalyst compared to the starting supported chromium catalyst material. In particular, the reduced chromium catalysts can comprise a significant proportion of chromium compounds from the supported chromium catalyst reduced during the irradiation step and can exhibit high catalytic activity. According to certain aspects, at least about 10 wt. %, at least about 20 wt. %, at least about 40 wt. %, at least about 60 wt. %, at least about 80 wt. %, at least about 90 wt. %, at least about 95 wt. %, or at least about 99 wt. % of the supported chromium catalyst (or hexavalent chromium compounds in the supported chromium catalyst) can be reduced to produce a reduced chromium catalyst.

Thus, according to one aspect, in the reduced chromium catalyst, less than or about 75% by weight of the chromium may be in the hexavalent state, while according to another aspect, less than or about 50% by weight of the chromium may be in the hexavalent state, while according to another aspect, less than or about 40% by weight of the chromium may be in the hexavalent state, and according to another aspect, less than or about 30% by weight of the chromium may be in the hexavalent state. The stated values are based on the total amount of chromium in the reduced chromium catalyst.

Additionally or alternatively, the chromium in the reduced chromium catalyst can be characterized by an average valence of less than or equal to about 5.25. Most commonly, the average valence of the chromium in the reduced chromium catalyst is less than or equal to about 5; alternatively, the average valence is less than or equal to about 4.75; alternatively, the average valence is less than or equal to about 4.5; alternatively, the average valence is less than or equal to about 4.25; or, alternatively, the average valence is less than or equal to about 4.

In addition, the effectiveness of the methods described herein can be characterized by the relative activity of the reduced chromium catalyst in the olefin polymerization reaction. According to some aspects, the catalytic activity of the reduced chromium catalyst can be greater (e.g., greater by at least 10%, at least 20%, at least 50%, at least 80%, etc.) than the catalytic activity of the supported chromium catalyst (which has not been treated by irradiation with light or exposed to light, but in the absence of a reducing agent, etc.). Additionally or alternatively, the reduced chromium catalyst (by irradiation with a reducing agent) can be compared with an otherwise identical catalyst calcined at the same temperature and using the same procedure, but then treated with the same reducing agent at an elevated temperature (e.g., 300 ^o C, 350 ^o C, 400 ^o C, 450 ° C, or 500 ^o C) to initiate reduction by thermal means in the absence of light. Thus, the reduced chromium catalyst can have a greater catalytic activity (e.g., greater by at least 10%, at least 20%, at least 50%, at least 80%, etc.) than the catalytic activity of an otherwise identical catalyst prepared using the same reducing agent at an elevated temperature without irradiation with light. These activity comparisons are carried out under the same polymerization conditions, which are suspension polymerization conditions at 105°C and 550 psig (approximately 3.8 MPa g).

CATALYST PRODUCTION SYSTEMS

According to another aspect of the present invention, a catalyst production system is provided, wherein according to such aspect, said catalyst production system may comprise (a) a catalyst production vessel configured to irradiate a chromium catalyst slurry on a support in a diluent using a light beam with a wavelength in the UV-visible region of the spectrum, (b) a catalyst inlet configured to introduce the chromium catalyst slurry on the support into the catalyst production vessel, wherein at least a portion of the chromium is in a hexavalent oxidation state, and (c) a reduced catalyst outlet configured to remove the reduced chromium catalyst slurry from the catalyst production vessel.

In general, the features of any of the catalyst production systems described herein (e.g., but not limited to, a catalyst production vessel, a light beam, a catalyst inlet, and a reduced catalyst outlet) are described herein independently, and these features may be combined in any combination to further describe the disclosed catalyst production systems. In addition, other devices or components of the catalyst production system may be present in the described catalyst production systems, unless otherwise specified. For example, the catalyst production system may further include a co-catalyst inlet configured to introduce a feed stream of any suitable co-catalyst into the catalyst production vessel. Additionally or alternatively, the catalyst production system may also include a reductant inlet configured to introduce a feed stream of any suitable reductant into the catalyst production vessel. In this way, the reductant may be separately fed into the catalyst production vessel. Additionally or alternatively, the diluent may comprise a reductant, or the diluent may be a reductant.

The catalyst preparation system may be configured to operate in a continuous mode, such as to provide a continuous feed stream of reduced chromium catalyst to the polymerization reactor via a reduced catalyst outlet of the catalyst preparation system. Alternatively, the catalyst preparation system may be configured to operate in a batchwise manner. In fact, the catalyst preparation vessel itself is not limited to any particular type and may typically be a stirred tank, a flow reactor vessel, or other suitable tank or vessel. The catalyst preparation vessel may be configured to operate at any temperature and pressure suitable for irradiating the chromium catalyst slurry.

Regardless of whether the production is batch or continuous, the catalyst preparation system can be configured to use any residence time sufficient to irradiate the chromium catalyst slurry on the support, while also simultaneously feeding a sufficient amount of reduced catalyst to any subsequent or additional process, such as a polymerization process. A suitable residence time can be the same or different (e.g. longer) from the above-mentioned exposure time used in the irradiation step in the chromium catalyst reduction methods. According to some aspects, the proposed system can be configured to use a residence time of from about 15 seconds to about 10 hours, from about 1 minute to about 6 hours, from about 5 minutes to about 1 hour, from about 10 minutes to about 2 hours, from about 1 minute to about 1 hour, or from about 1 minute to about 15 minutes.

This document includes aspects of the present invention, in which the light beam source is sunlight. However, according to aspects, in which the light source is an artificial light source, for example, a UV lamp, a fluorescent white light and/or an LED diode, the catalyst production system may further comprise a lamp module for placing the light source and facilitating irradiation of the chromium catalyst on the substrate inside the catalyst production vessel. The lamp module may be located inside or outside the catalyst production vessel. In the case of placing the lamp module inside the catalyst production vessel, said lamp module can be placed in the reaction space of the vessel so that the suspension containing the chromium catalyst on the substrate and a diluent (which may be a reducing agent), or the suspension, the diluent and the reducing agent can flow around the lamp module, which can be placed inside a quartz tube or other suitable barrier to protect the lamp from direct contact with the suspension and the solid chromium catalyst. A non-limiting example of such a configuration is shown in U.S. Patent Publication No. 2014/0221692, relating to flow reactor vessels and reactor systems and incorporated herein by reference in its entirety.

Alternatively, the lamp module can be placed outside the catalyst production vessel. Thus, the catalyst production vessel can comprise a window or a screen that allows light emitted by the lamp to pass into the catalyst production vessel and irradiate (e.g., reduce) the supported chromium catalyst and the reducing agent located inside the vessel. The lamp module can be configured to emit a light beam of any wavelength or wavelength range in the UV-visible region of the spectrum, as described above for the irradiation step in the chromium catalyst reduction methods.

The catalyst production system may further comprise (d) a controller configured to regulate the residence time of the chromium catalyst on the support in the catalyst production vessel, and/or the temperature of the catalyst production vessel, and/or the intensity of the light beam, and/or the wavelength of the light beam, and/or the amount of reduced chromium catalyst, and/or the molar ratio of the reducing agent to chromium. The controller may also be configured to regulate the flow rate of the slurry entering the catalyst inlet and the flow rate exiting the reduced catalyst outlet. When feeding the co-catalyst to the catalyst production vessel, the controller may be further configured to regulate the flow rate of the co-catalyst feed. Similarly, when feeding the reducing agent to the catalyst production vessel (and separately from the diluent), the controller may also be configured to regulate the flow rate of the reducing agent feed entering the catalyst production vessel.

As a non-limiting example, if the molar ratio of reductant to chromium in the catalyst production vessel is below a target value (i.e., too low), the controller may reduce the flow rate of the slurry (containing the supported chromium catalyst) entering the vessel and/or increase the flow rate of the reductant feed stream entering the vessel.

An exemplary catalyst production system according to aspects of the present invention is shown in Fig. 1 . The catalyst production system 100 includes a catalyst production vessel 110, an inlet 101 for supported chromium catalyst and an outlet 115 for reduced catalyst. In addition, a reactor 120 is also shown in Fig. 1 to demonstrate that the catalyst production systems described herein can be integrated as part of a polymerization reactor system, such as any of the systems described herein. The catalyst production system 100 also includes a co-catalyst inlet 103 configured to introduce a co-catalyst feed stream into the catalyst production vessel (if necessary) and a reductant inlet 105 configured to introduce a reductant feed stream into the catalyst production vessel (if necessary). Alternatively, the reducing agent may be present in the supported chromium catalyst feed stream entering the vessel 110 through the inlet 101. Additional inlets and feed streams entering the catalyst production vessel may also be present, although individual feed streams entering the catalyst production vessel are not shown. The lamp module 130 is shown as being located inside or outside the catalyst production vessel, and said module is capable of irradiating within the vessel 110. Furthermore, in Fig. 1 shows a process variable 132 (e.g., temperature, residence time, relative amount of reducing agent, etc.), the value of which can be transmitted from the vessel 110 for producing the catalyst to the measuring system 140 for determining various process and operating conditions in the vessel 110. The process variable 134 from the outlet 115 for the reduced catalyst (e.g., flow rate, amount of reduced catalyst, etc.) and/or the process variable 136 from the reactor 120 can be transmitted to the measuring system 140.

Information or data 145 from the measuring system 140 can be transmitted to the controller 150, which can then control or adjust 155 the flow rate of the material in any opening selected from the inlet 101, the inlet 103, the inlet 105 and the outlet 115. Alternatively, or additionally, the controller 150 can independently control or adjust 155 various process or operating conditions - for example, temperature, residence time, relative amount of reducing agent, light intensity, wavelength of light, etc. - of the vessel 110 for producing the catalyst.

POLYMERIZATION REACTOR SYSTEMS AND POLYMERIZATION METHODS

Included in the present document are polymerization reactor systems, wherein according to one aspect of the present invention, said polymerization reactor systems can include any of the catalyst production systems described herein and a reactor configured to contact a reduced chromium catalyst with an olefin monomer and an optional olefin comonomer under polymerization conditions to produce an olefin polymer. The present invention also includes polymerization methods, wherein according to another aspect of the present invention, the polymerization method may comprise (I) irradiating a reducing agent and a supported chromium catalyst comprising chromium in a hexavalent oxidation state with a light beam of a wavelength in the UV-visible region of the spectrum to reduce at least a portion of the supported chromium catalyst to produce a reduced chromium catalyst, and (II) contacting any reduced chromium catalyst described herein (e.g., a reduced chromium catalyst obtained by any method for reducing chromium catalysts described above) and an optional cocatalyst with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an olefin polymer. Any of the features of step (I) may be the same as the features described herein (e.g., reducing agent, light beam source, wavelength, etc.) for the methods of reducing a chromium catalyst on a support.

Advantageously, the use of an irradiation step to produce a reduced catalyst (prior to polymerization initiation) may result in a more fully activated catalyst that has been reduced and alkylated prior to entering the polymerization reactor. The resulting increase in overall activity (the catalyst no longer requires reduction/alkylation after entering the polymerization reactor) allows for the use of less catalyst and lower polymerization temperatures, which in turn may reduce polymer swelling and fouling and improve overall operating efficiency.

Unsaturated monomers that can be used with the catalyst compositions and polymerization methods of the present invention can generally include olefinic compounds containing from 2 to 30 carbon atoms per molecule and at least one olefinic double bond. The present invention includes homopolymerization processes using a single olefin, such as ethylene or propylene, as well as copolymerization reactions, terpolymerization reactions, etc. using an olefinic monomer with at least one other olefinic compound. For example, the resulting ethylene copolymers, terpolymers, etc. can generally contain a large amount of ethylene (>50 mole percent) and a small amount of comonomer (<50 mole percent), although this is not a requirement. Comonomers that can be copolymerized with ethylene can often contain from 3 to 20 carbon atoms or from 3 to 10 carbon atoms in their molecular chain.

According to the present invention, acyclic, cyclic, polycyclic, terminal (α), internal, linear, branched, substituted, unsubstituted, functionalized and non-functionalized olefins can be used. For example, typical unsaturated compounds that can be polymerized with the catalyst compositions of the present invention can include, but are not limited to, ethylene, propylene, 1-butene, 2-butene, 3-methyl-1-butene, isobutylene, 1-pentene, 2-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 2-hexene, 3-hexene, 3-ethyl-1-hexene, 1-heptene, 2-heptene, 3-heptene, four normal octenes (e.g., 1-octene), four normal nonenes, five normal decenes, and the like, or mixtures of two or more of these compounds. Cyclic and bicyclic olefins, including but not limited to cyclopentene, cyclohexene, norbornylene, norbornadiene, and the like, can also be polymerized as described herein. Additionally, styrene can be used as a monomer according to the present invention. In one aspect, the olefin monomer can comprise a C ₂ -C ₂₀ olefin; alternatively, a C ₂ -C ₂₀ alpha-olefin; alternatively, a C ₂ -C ₁₀ olefin; alternatively, a C ₂ -C ₁₀ alpha-olefin; alternatively, the olefin monomer can comprise ethylene; or alternatively, the olefin monomer can comprise propylene.

If a copolymer (or alternatively a terpolymer) is desired, the olefin monomer and the olefin comonomer may independently comprise, for example, a _C2 - _C20 alpha-olefin. According to some aspects, the olefin monomer may comprise ethylene or propylene, which is copolymerized with at least one comonomer (for example, a _C2 - _C20 alpha-olefin, a _C3 - _C20 alpha-olefin, etc.). According to one aspect of the present invention, the olefin monomer used in the polymerization process may comprise ethylene. According to such an aspect, examples of suitable olefin comonomers can include, but are not limited to, propylene, 1-butene, 2-butene, 3-methyl-1-butene, isobutylene, 1-pentene, 2-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 2-hexene, 3-ethyl-1-hexene, 1-heptene, 2-heptene, 3-heptene, 1-octene, 1-decene, styrene, and the like, or combinations thereof. According to another aspect of the present invention, the olefin monomer can comprise ethylene and the comonomer can comprise a C ₃ -C ₁₀ alpha olefin; alternatively, the comonomer can comprise 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, styrene, or any combination thereof; alternatively, the comonomer may comprise 1-butene, 1-hexene, 1-octene, or any combination thereof; alternatively, the comonomer may comprise 1-butene; alternatively, the comonomer may comprise 1-hexene; or alternatively, the comonomer may comprise 1-octene.

The chromium catalysts of the present invention are suitable for any process for polymerizing olefins using various types of polymerization reactor systems and reactors. The polymerization reactor system may include any polymerization reactor capable of polymerizing olefin monomers and comonomers (one or more comonomers) to produce homopolymers, copolymers, terpolymers, and the like. The various types of reactors include reactors that may be referred to as a batch reactor, a slurry reactor, a gas phase reactor, a solution reactor, a high pressure reactor, a tubular reactor, an autoclave reactor, and the like, or combinations thereof. Polymerization conditions for the various types of reactors are well known to those skilled in the art. Gas phase reactors may include fluidized bed reactors or multistage horizontal reactors. Slurry reactors may comprise vertical or horizontal loops. High pressure reactors may include autoclave or tubular reactors. Typically, these types of reactors can be operated in a continuous mode. In continuous processes, batch or continuous discharge of polymer product can be used. Polymerization reactor systems and methods can also include partial or complete direct recycling of unreacted monomer, unreacted comonomer, and/or diluent (e.g., the same or different from the diluent used during chromium catalyst reduction).

The polymerization reactor systems of the present invention may comprise a single reactor type in the system or multiple reactors of the same or different types (e.g., a single reactor, a dual reactor, more than two reactors). For example, the polymerization reactor system may comprise a solution reactor, a gas phase reactor, a slurry reactor, or a combination of two or more of these reactors. The production of polymers in multiple reactors may comprise multiple stages in at least two separate polymerization reactors interconnected by a transfer device that allows the produced polymer to be transferred from the first polymerization reactor to the second reactor. The polymerization conditions in one of the reactors may differ from the operating conditions in the other reactor(s). Alternatively, polymerization in multiple reactors may comprise manual transfer of polymer from one reactor to subsequent reactors to continue polymerization. Multi-reactor systems may include any combination, including but not limited to, multiple loop reactors, multiple gas phase reactors, a combination of loop and gas phase reactors, multiple high-pressure reactors, or a combination of high-pressure reactors with loop and/or gas phase reactors. Multiple reactors may operate in series or in parallel or/and in series and in parallel. Accordingly, the present invention includes polymerization reactor systems comprising one reactor, comprising two reactors, and comprising more than two reactors. According to some aspects of the present invention, the polymerization reactor system may comprise a slurry reactor, a gas phase reactor, a solution reactor, and multiple reactor combinations thereof.

According to one aspect, the polymerization reactor system may comprise at least one loop slurry reactor, such as comprising vertical or horizontal loops. The monomer, diluent, catalyst and optional comonomer may be continuously fed to the loop reactor wherein polymerization occurs. In general, continuous processes may comprise continuously introducing the monomer/comonomer, catalyst and diluent into the polymerization reactor and continuously removing a slurry comprising polymer particles and diluent from such reactor. The reactor effluent may be flashed to remove solid polymer from liquids comprising diluent, monomer and/or comonomer. Various technologies may be used to perform such a separation step, including, but not limited to, flashing, which may comprise any combination of heat and pressure reduction, separation by cyclonic action in either a cyclone or a hydrocyclone, or separation by centrifugation.

A typical suspension polymerization process (also known as a particle process) is described, for example, in U.S. Patent Nos. 3,248,179, 4,501,885, 5,565,175, 5,575,979, 6,239,235, 6,262,191, 6,833,415, and 8,822,608, each of which is incorporated herein by reference in its entirety.

Suitable diluents used in slurry polymerization include, but are not limited to, the monomer being polymerized and hydrocarbons that are liquid under the reaction conditions. Examples of suitable diluents include, but are not limited to, hydrocarbons such as propane, cyclohexane, isobutane, n-butane, n-pentane, isopentane, neopentane, and n-hexane. Some loop reactor polymerization reactions may occur under bulk conditions that do not employ a diluent, such as conditions that may be used in the bulk polymerization of propylene to produce polypropylene homopolymers.

According to another aspect, the polymerization reactor system can comprise at least one gas phase reactor (e.g., a fluidized bed reactor). Such reactor systems can employ a continuous recycle stream comprising one or more monomers continuously circulating through a fluidized bed in the presence of a catalyst under polymerization conditions. The recycle stream can be removed from the fluidized bed and returned to the reactor. At the same time, polymer product can be removed from the reactor and new or fresh monomer can be added to replace the polymerized monomer. Such gas phase reactors can comprise a multistage gas phase olefin polymerization process in which olefins are polymerized in the gas phase in at least two independent gas phase polymerization zones while simultaneously feeding a catalyst-containing polymer produced in the first polymerization zone to the second polymerization zone. One type of gas phase reactor is described in U.S. Patent Nos. 5,352,749, 4,588,790, 5,436,304, 7,531,606, and 7,598,327, each of which is incorporated herein by reference in its entirety.

According to another aspect, the polymerization reactor system may include a high-pressure polymerization reactor, for example, may include a tubular reactor or an autoclave reactor. Tubular reactors may have several zones in which fresh monomer, initiators or catalysts are added. The monomer may be entrained in an inert gas stream and introduced into one of the reactor zones. The initiators, catalysts and/or catalyst components may be entrained in a gas stream and introduced into another reactor zone. The gas streams may be mixed for polymerization. Heat and pressure may be used appropriately in such high-pressure polymerization reactors to ensure optimal polymerization reaction conditions.

According to another aspect, the polymerization reactor system may comprise a solution polymerization reactor in which the monomer/comonomer may be contacted with the catalyst composition by suitable mixing or other means. A support comprising an inert organic diluent or an excess of monomer may be used. If desired, the monomer/comonomer may be contacted in the vapor phase with the catalyst reaction product in the presence or absence of a liquid substance. The polymerization zone may be maintained at a temperature (e.g., 150°C to 180°C) and pressure that will result in a polymer solution in the reaction medium. Mixing may be used to provide better temperature control and maintain homogeneity of the polymerization mixtures throughout the polymerization zone. Suitable means are used to remove the exothermic heat of polymerization.

In some aspects, a polymerization reactor system may include any combination of a feedstock feed system, a catalyst and/or catalyst component feed system, and/or a polymer recovery system, including a continuous system. In other aspects, suitable reactor systems may include systems for feedstock purification, catalyst storage and preparation, extrusion, reactor cooling, polymer recovery, fractionation, recycling, storage, unloading, laboratory analysis, and process control, in addition to or as part of the catalyst production systems described herein.

The catalyst compositions and/or polymerization methods described herein can often employ a cocatalyst. In some aspects, the cocatalyst can comprise a hydrocarbyl metal compound, examples of which include nonhalogen metal hydrocarbyl compounds, halide metal hydrocarbyl compounds, nonhalogen metal alkyl compounds, halide metal alkyl compounds, and so on, and in which the metal can be any suitable metal, often a Group 13 metal. Thus, in certain aspects of the present invention, the metal can be boron or aluminum, wherein the cocatalyst can comprise a hydrocarbyl or alkyl boron, or a hydrocarbyl or alkyl aluminum, as well as combinations thereof.

In one aspect, the co-catalyst may include an aluminoxane compound, an organoaluminum compound, or an organoboron compound, wherein the co-catalyst comprises combinations of more than one compound comprising the co-catalyst. Typical and non-limiting examples of aluminoxanes include methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, n-propylaluminoxane, isopropylaluminoxane, n-butylaluminoxane, tert-butylaluminoxane, sec-butylaluminoxane, isobutylaluminoxane, 1-pentylaluminoxane, 2-pentylaluminoxane, 3-pentylaluminoxane, isopentyl aluminoxane, neopentyl aluminoxane, and the like, or any combination thereof. Representative and non-limiting examples of organoaluminum compounds include trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diisobutylaluminum hydride, diethylaluminum ethylate, diethylaluminum chloride, and the like, or any combination thereof. Representative and non-limiting examples of organoboron compounds include tri-n-butylborane, tripropylborane, triethylborane, and the like, or any combination thereof. Cocatalysts that can be used in the catalytic compositions of the present invention are not limited to the cocatalysts described above. Other suitable cocatalysts (such as organomagnesium and organolithium compounds) are well known to those skilled in the art, including, for example, the catalysts described in U.S. Patent Nos. 3,242,099, 4,794,096, 4,808,561, 5,576,259, 5,807,938, 5,919,983, 7,294,599, 7,601,665, 7,884,163, 8,114,946, and 8,309,485, which are incorporated herein by reference in their entireties.

Polymerization conditions that can be monitored, adjusted and/or controlled to improve efficiency and provide desired polymer properties may include, but are not limited to, reactor temperature, reactor pressure, catalyst flow rate into the reactor, monomer (and comonomer, if used) flow rate into the reactor, monomer concentration in the reactor, olefin polymer yield rate, recycle rate, hydrogen flow rate (if used), reactor cooling status, etc. The polymerization temperature can affect catalyst productivity, polymer molecular weight and molecular weight distribution. A suitable polymerization temperature can be any temperature below the depolymerization temperature according to the Gibbs free energy equation. Typically, such a temperature is from about 60 °C to about 280 °C, such as from about 60 °C to about 185 °C, from about 60 °C to about 120 °C, or from about 130 °C to about 180 °C, depending on the type of polymerization reactor, grade of polymer, etc. In some reactor systems, the temperature of the polymerization reactor may generally be from about 70 °C to about 110 °C or from about 125 °C to about 175 °C. Various polymerization conditions may be maintained substantially constant, such as to produce a particular grade of olefin polymer.

Suitable pressures will also vary depending on the type of reactor and polymerization. Pressures for liquid phase polymerization in a loop reactor can typically be less than 1,000 psig (6.9 MPa). Pressures for gas phase polymerization can typically be between 200 and 500 psig (1.4 MPa and 3.4 MPa). High pressure polymerization in tubular or autoclave reactors can generally be carried out at pressures of approximately 20,000 to 75,000 psig (138 to 517 MPa). Polymerization reactors can also be operated in the supercritical region, which typically occurs at higher temperatures and pressures (e.g., above 92°C and 700 psig (4.83 MPa)). Operating at conditions above the critical point on the pressure/temperature diagram (supercritical phase) can provide advantages to such a polymerization reaction process.

Aspects of the present invention also relate to olefin polymerization processes carried out in the absence of added hydrogen. The olefin polymerization process of the present invention may comprise contacting a reduced chromium catalyst and an optional cocatalyst with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an olefin polymer, wherein such polymerization process is carried out in the absence of added hydrogen (no hydrogen is added to the polymerization reactor system). One skilled in the art will appreciate that hydrogen may be generated in situ by certain catalyst systems in various olefin polymerization processes, and the amount generated may vary depending on the particular catalyst components used, the type of polymerization process used, the polymerization reaction conditions used, and so on.

In other aspects, it may be desirable to carry out the polymerization process in the presence of a certain amount of added hydrogen. Accordingly, the method of polymerizing olefins according to the present invention may include contacting a reduced chromium catalyst and an optional cocatalyst with an olefin monomer and, optionally, an olefin comonomer in a polymerization reactor system under polymerization conditions to form an olefin polymer, wherein such polymerization process is carried out in the presence of added hydrogen (hydrogen is added to the polymerization reactor system). For example, the ratio of hydrogen to olefin monomer can be controlled in the polymerization process, often by means of the ratio of the hydrogen fed to the olefin monomer entering the reactor. The amount of hydrogen added to the process (based on the amount of olefin monomer) can be controlled at a molar percentage concentration of generally from about 0.05 to about 20 mol %, from about 0.1 to about 15 mol %, from about 0.25 to about 10 mol %, or from about % or from about 0.5 to about 10 mol %. According to some aspects of the present invention, for a particular grade of polymer, the ratio of hydrogen in the feedstock or reactant to olefin monomer can be maintained substantially constant during the polymerization cycle. That is, a particular value for the hydrogen:olefin monomer ratio can be selected and said ratio can be maintained during the polymerization cycle within about +/- 25%. In addition, for a particular grade of polymer, the addition of comonomer (or comonomers) can be, and typically is, substantially constant throughout the polymerization cycle.

However, in other aspects, it is contemplated that the monomer, comonomer(s) and/or hydrogen may be fed intermittently to the reactor, such as in a manner similar to that employed in U.S. Patent No. 5,739,220 and U.S. Patent Publication No. 2004/0059070, the disclosures of which are incorporated herein by reference in their entirety.

The concentration of reactants entering the polymerization reactor system can be controlled to produce resins with specific physical and mechanical properties. The proposed end-use product to be produced from the polymer resin and the method of producing that product can ultimately determine the desired properties and characteristics of the polymer. Mechanical properties include tensile strength, flexural strength, impact strength, creep, stress relaxation, and hardness tests. Physical properties include measurements of density, molecular weight, molecular weight distribution, melting point, glass transition temperature, crystallization temperature, density, stereoregularity, crack formation, long-chain branching, and rheological measurements.

As discussed above, a typical polymerization reactor system consistent with aspects of the present invention is illustrated in Fig. 1. The polymerization reactor system comprises a catalyst production system 100 (comprising a catalyst production vessel 110, a lamp module 130, a measuring system 140, and a controller 150) and a reactor 120. The catalyst production system 100 operates as described above. The process parameters 132, 134, 136 are transmitted to the measuring system 140 for determining various process and operating conditions, and, accordingly, the measuring system 140 can include any suitable measuring device or equipment (for example, a flow meter, a thermocouple, etc.) for determining specific process and operating conditions in the catalyst production vessel 110, the reduced catalyst outlet 115 and/or the reactor 120. As indicated above, the polymerization reactor system comprises a reduced catalyst outlet 115 configured to remove the reduced chromium catalyst slurry from the catalyst production vessel 110 and feed it into the reactor 120.

POLYMERS AND PRODUCTS

The present invention also relates to polymers obtained using any of the polymerization processes described herein and includes said polymers. Articles of industrial production may be made from and/or contain polymers obtained according to the present invention.

The olefin polymers provided herein may include any polymer formed from any olefin monomer and optional comonomer(s) described herein. For example, an olefin polymer may include an ethylene homopolymer, an ethylene copolymer (e.g., ethylene/α-olefin, ethylene/1-butene, ethylene/1-hexene, ethylene/1-octene, etc.), a propylene homopolymer, a propylene copolymer, an ethylene terpolymer, a propylene terpolymer, and the like, including any combinations thereof. In one aspect, the olefin polymer may be an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, or an ethylene/1-octene copolymer, while in another aspect, the olefin polymer may be an ethylene/1-hexene copolymer.

If the resulting polymer obtained according to the present invention is, for example, an ethylene polymer, its properties can be characterized using various analytical methods known and used in the polyolefin industry. Articles of industrial production can be made from olefin polymers (for example, ethylene polymers) according to the present invention and/or can contain them, whereby typical properties of said polymers are given below.

An illustrative and non-limiting example of an ethylene polymer (e.g., an ethylene homopolymer and/or an ethylene copolymer) according to the present invention can have an Mw/Mn ratio in the range of from about 30 to about 110, an Mz/Mw ratio in the range of from about 4 to about 10, and a CY-a parameter in the range of from about 0.2 to about 0.4. Other suitable ranges of the Mw/Mn ratio of the ethylene polymer include ranges from about 35 to about 105, from about 40 to about 100, from about 45 to about 95, or from about 50 to about 90. Similarly, other suitable ranges of the Mz/Mw ratio include ranges from about 5 to about 9, from about 5 to about 8, from about 5.5 to about 7.5, or from about 6 to about 7. Further, other suitable ranges of the CY-a parameter include ranges from about 0.23 to about 0.38, from about 0.25 to about 0.35, or from about 0.27 to about 0.34. In addition, the ethylene polymer can be further characterized by an Mn of from about 3000 to about 12000 g/mol, from about 4000 to about 11000 g/mol, from about 4000 to about 10000 g/mol, from about 5000 to about 10000 g/mol, or from about 5500 to about 9500 g/mol. Additionally or alternatively, the Mw of the ethylene polymer can be from about 250000 to about 700000 g/mol, from about 300000 to about 675000 g/mol, from about 350000 to about 625000 g/mol, or from about 375000 to about 600000 g/mol. Additionally or alternatively, the HLMI of the ethylene polymer can be less than or equal to about 10, less than or equal to about 8, less than or equal to about 5, or less than or equal to about 4 g/10 min. Additionally or alternatively, the ethylene polymer can be characterized by a long chain branching (LCBs) amount of from about 0.5 to about 4, from about 0.5 to about 3, from about 0.7 to about 2.8, or from about 1 to about 2.5 LCBs per million total carbon atoms.

Another illustrative and non-limiting example of an ethylene polymer according to the present invention can have an Mw/Mn ratio in the range of from about 6 to about 15, an Mz/Mw ratio in the range of from about 30 to about 70, and a melt flow index in the range of from about 0.5 to about 10 g/10 min. Other suitable ranges of the Mw/Mn ratio include ranges from about 7 to about 14, from about 8 to about 13, from about 8 to about 12, or from about 9 to about 10. Similarly, other suitable ranges of the Mz/Mw ratio include ranges from about 35 to about 65, from about 40 to about 60, from about 45 to about 55, or from about 47 to about 51. Further, other suitable ranges of the melt flow index include ranges from about 0.5 to about 5, from about 0.7 to about 7, or from about 1 to about 5 g/10 min. In addition, the ethylene polymer can be further characterized by an Mn of from about 10,000 to about 25,000 g/mol, from about 13,000 to about 22,000 g/mol, from about 15,000 to about 20,000 g/mol, or from about 16,000 to about 18,000 g/mol. Additionally or alternatively, the Mw of the ethylene polymer can be from about 100,000 to about 400,000 g/mol, from about 100,000 to about 300,000 g/mol, from about 110,000 to about 250,000 g/mol, or from about 140,000 to about 200,000 g/mol. Additionally or alternatively, the ethylene polymer can be characterized by LCBs that are less than or equal to about 2, less than or equal to 1, less than or equal to about 0.8, less than or equal to about 0.5, or less than or equal to about 0.2 LCBs per million total carbon atoms.

Unless previously indicated, such illustrative and non-limiting examples of ethylene polymers of the present invention may also have any of the polymer properties listed below, and in any combination.

Olefin polymers (e.g., ethylene homopolymers and/or copolymers) produced according to some aspects of the present invention may generally have a melt flow index (MI) of from 0 to about 100 g/10 min. According to other aspects of the present invention, melt values in the range of from 0 to about 50 g/10 min, from 0 to about 25 g/10 min, or from 0 to about 10 g/10 min are provided. For example, a polymer according to the present invention may have a melt flow index in the range of from 0 to about 5, from 0 to about 3, from 0 to about 1, or from 0 to about 0.5 g/10 min.

The olefin polymers produced according to the present invention can have a high load melt flow index (HLMI) of less than or equal to about 200, less than or equal to about 150, or less than or equal to about 100 g/10 min. Suitable HLMI ranges can include, but are not limited to, ranges from 0 to about 150, from about 2 to about 120, from about 1 to about 100, from about 1 to about 80, from about 2 to about 80, from about 4 to about 60, from about 8 to about 60, from about 1 to about 50, from about 4 to about 50, from about 3 to about 40, or from about 6 to about 40 g/10 min.

In addition, the olefin polymers produced according to the present invention can be characterized by their melt flow index properties as compared to olefin polymers produced using comparable (otherwise identical) catalysts produced without an irradiation step (e.g., a reduced chromium catalyst can be produced using a heating step to reduce hexavalent chromium compounds; a supported chromium catalyst without reduction, etc.). According to certain aspects, the MI (or HLMI) of the olefin polymer produced by the inventive method can be greater than 50%, greater than 80%, greater than 90%, greater than 100%, greater than 120%, greater than 150%, or greater than 200% of the MI (or HLMI) of an olefin polymer produced without an irradiation step under the same polymerization conditions.

The density of the olefin polymers produced using the chromium catalysts and methods described herein is often greater than or equal to about 0.89 g/ ^cm3 . According to one aspect of the present invention, the density of the olefin polymer can be from about 0.89 to about 0.96 g/ ^cm3 . However, in another aspect, the density can be from about 0.91 to about 0.95 g/ ^cm3 , such as from about 0.91 to about 0.94 g/ ^cm3 , from about 0.92 to about 0.955 g/ ^cm3 , or from about 0.93 to about 0.955 g/ ^cm3 .

In one aspect, the olefin polymers described herein can have a weight average molecular weight (Mw) in the range of from about 50,000 to about 2,000,000, from about 50,000 to about 1,000,000, from about 50,000 to about 700,000, from about 75,000 to about 500,000, from about 100,000 to about 500,000, from about 100,000 to about 400,000, or from about 150,000 to about 300,000 g/mol.

In one aspect, the olefin polymers described herein can have a number average molecular weight (Mn) in the range of from about 2,000 to about 250,000, from about 2,000 to about 100,000, from about 2,000 to about 50,000, from about 5,000 to about 200,000, from about 5,000 to about 150,000, or from about 5,000 to about 50,000 g/mol. In another aspect, the Mn of the olefin polymers described herein can be from about 10,000 to about 100,000, from about 10,000 to about 75,000, from about 25,000 to about 150,000, or from about 50,000 to about 150,000 g/mol.

Olefin polymers, whether homopolymers, copolymers, etc., can be molded to form various articles of industrial manufacture. Articles that can contain the polymers of the present invention include, but are not limited to, an agricultural film, an automobile part, a bottle, a drum, a fiber or fabric, a food packaging film or container, an article for use in food service, a fuel tank, a geomembrane, a household container, a lining material, a molded article, a medical device or material, a pipe, a sheet or tape, a toy, and the like. Various methods can be used to produce the listed articles. Non-limiting examples of such methods include injection molding, blow molding, rotomolding, film extrusion, sheet extrusion, profile extrusion, thermoforming, etc. In addition, additives and modifiers are often added to these polymers to ensure efficient processing of the polymer or useful properties of the final product. Such methods and materials are described in Modern Plastics Encyclopedia , Mid-November 1995 Issue, Vol. 72, No. 12; and Film Extrusion Manual - Process, Materials, Properties , TAPPI Press, 1992; the disclosures of which are incorporated herein by reference in their entirety.

Additionally, provided herein is a method of forming or manufacturing an article of manufacture comprising a polymer produced by any of the polymerization processes described herein. For example, the method may comprise (i) contacting a chromium catalyst (e.g., prepared as described herein) and an optional cocatalyst with an olefin monomer and an optional olefin comonomer under polymerization conditions in a polymerization reactor system to produce an olefin polymer; and (ii) forming an article of manufacture comprising the olefin polymer (e.g., having any of the properties of the polymers described herein). The forming step may comprise mixing, melt molding, extrusion, casting, or thermoforming, and the like, including combinations thereof.

EXAMPLES

The present invention is further illustrated by the following examples, which should in no way be considered as limitations imposed on the scope of the present invention. After reading the description provided herein, a person skilled in the art will be able to suggest various other aspects, modifications and their equivalents that do not depart from the spirit of the present invention or the scope of the appended claims.

The melt flow index (MI, g/10 min) was determined according to ASTM D1238 at 190°C with a load of 2.16 kg, I ₁₀ (g/10 min) was determined according to ASTM D1238 at 190°C with a load of 10 kg, and the high load melt flow index (HLMI, g/10 min) was determined according to ASTM D1238 at 190°C with a load of 21.6 kg. The BET surface area can be determined using the BET nitrogen adsorption method described by Brunaur et al., J. Am. Chem. Soc. , 60, 309 (1938). The total pore volume can be determined according to Halsey, G. D., J. Chem. Phys. (1948), 16, pp. 931.

In the examples given, supported chromium catalysts containing hexavalent chromium compounds were irradiated with UV-visible light in the presence of various reducing agents and under various processing conditions. Prior to irradiation, the supported chromium catalysts were calcined at a given temperature in dry air (oxidizing atmosphere) in a fluidized bed for three hours to convert the chromium compounds to their corresponding hexavalent oxidation state.

For each of the examples below, approximately two grams of supported catalyst were first loaded into an airtight glass container at 25°C, optionally in the presence of a reducing agent. The glass container was then exposed to light as indicated in Tables I through IV below. For examples in which the glass container was exposed to sunlight, the container was taken outside and placed in direct sunlight, with the container rotated slowly to ensure uniform exposure of the supported chromium catalyst mixture. For examples in which the glass container was exposed to artificial light, the sample was placed in a box containing a fluorescent light source emitting light in the UV-visible region of the spectrum. Examples not exposed to light were stored in dim light or wrapped in foil to block light from entering the glass container. The reduction of the supported chromium catalysts was monitored by color change. For each catalyst, the original hexavalent chromium catalyst on the support was orange in color, which darkened significantly when the catalyst was exposed to light in the presence of a reducing agent, indicating reduction of the original chromium catalyst on the support.

The recovered chromium catalysts prepared as described above were used in polymerization experiments conducted in a 2 L stainless steel autoclave reactor containing 1.2 L of isobutane as a diluent. The polymerization reactions were carried out in the dark with ethylene supplied as needed to maintain a reactor pressure of 550 psig (approximately 3.8 MPa g). The reactor temperature was maintained at 105 °C (unless otherwise noted) throughout the experiment by an automatic heating and cooling system. For the copolymerization experiments, 1-hexene was injected with the initial ethylene feed. At the end of each experiment, the resulting polymer was dried at 60 °C under reduced pressure.

EXAMPLES 1-20

In Examples 1-20, a supported chromium catalyst comprising silica-titania (2.5 wt. % Ti and 1.0 wt. % Cr) was used. The Cr/silica-titania catalyst had a BET surface area of 500 ^m2 /g, a pore volume of 2.5 ml/g, and an average particle size of 130 μm. The Cr/silica-titania catalysts were calcined at 850 °C (unless otherwise specified) in dry air (oxidizing atmosphere) to convert the corresponding chromium compounds to the hexavalent oxidation state. Tables I-II list various catalyst reduction conditions, catalyst productivity (grams of polyethylene (PE) per gram of catalyst), catalyst activity (grams of polyethylene per gram of catalyst per hour), and HLMI, I ₁₀ , and MI (g/10 min) of the resulting polymers.

Comparative Examples 1-6 describe attempts to reduce the hexavalent chromium present in Cr/silica-titania catalysts without irradiating the catalyst with light in the presence of a reducing agent. As shown in Examples 1-2, in the absence of a reducing agent, the catalyst was unaffected by light (orange color). In contrast, in the presence of various reducing agents, each of Samples 9-20 underwent a color change after irradiation with light after only 10 minutes, and the color change persisted after the light exposure ceased. Surprisingly, in the presence of a reducing agent, even brief irradiation with light resulted in a color change, indicating the reduction of chromium to lower valence chromium compounds. In fact, the catalytic activity and potential melt flow index of the catalysts were enhanced by relatively brief exposure to light, as shown in Examples 9, 13, and 17 according to the present invention.

In addition to the ethylene reduction methods, the reduction step has surprisingly proven effective with hydrocarbons that are relatively difficult to oxidize, such as methane and benzene. Examples 3-6 demonstrate the difficulty of reducing Cr(VI) catalysts in the presence of the hydrocarbon methane using conventional methods. In Examples 3-6, methane was passed through the catalysts in a fluidized bed (in the absence of light), requiring heating to 350°C and above (Examples 4-6) before a color change was observed. In contrast, and surprisingly, exposing catalyst samples to sunlight in the presence of methane, without heating, caused a color change in the catalyst mixture within a few minutes (Example 13). Even more surprisingly, reduction in the presence of methane by the process of the present invention did not significantly reduce the catalytic activity and potential melt flow index, indicating that the catalyst prepared in the presence of light is fundamentally different from the catalyst prepared by conventional methods. Noteworthy is the higher catalytic activity and melt flow rate properties of Examples 13-14 compared to Examples 3-6.

Examples 15-17 are additional examples of reduction processes using compounds that are traditionally considered poor reducing agents, including tetrafluoroethane and benzene. Each sample showed a distinct and rapid color change upon irradiation with light. The use of benzene resulted in increased catalytic activity and melt flow properties comparable to Comparative Examples 1-2.

In examples 18-19 according to the present invention, the reduction was carried out using H ₂ as the reducing agent. Surprisingly, such reduction within a few minutes resulted in an active catalyst having an increased MI potential and comparable activity compared to comparative example 7. This result is unexpected, especially since thermal reduction in hydrogen typically results in a relatively inactive catalyst with a low MI potential.

Comparative Example 8 is provided for direct comparison with Example 20, in which the Cr/silica-titania catalyst was calcined at slightly elevated temperatures (871 °C) before being reduced in the presence of methane for 6 hours. The resulting reduced Cr/silica-titania catalysts were used in the copolymerization of ethylene/1-hexene, and surprisingly, both the catalytic activity and the melt flow index properties of the catalyst reduced in the presence of light were higher than those of the Cr(VI)/silica-titania catalyst prepared according to Comparative Example 8.

Table I. Comparative Examples 1-8 using Cr/silicon dioxide-titanium dioxide without light reduction

Example Reducing agent Processing Color Performance
(g PE/g catalyst) Activity
(g/g/hour) HLMI
(g/10 min) I ₁₀
(g/10
min) MI
(g/10
min) 1 absent missing, 1 week orange 2315 3307 110 27.2 1.97 2 absent light,
1 week orange 2434 3319 96 23.7 1.75 3 methane none (300 °C) orange 3087 3705 39 8.7 0.55 4 methane absent
(350 °C) green 2209 3488 28 6.5 0.46 5 methane absent
(400 °C) green 1823 3646 22 5.2 0.32 6 methane absent
(450 °C) green 2338 2646 17 3.8 0.23 7* absent absent orange 2919 3434 47 10.3 0.64 8 ^*† absent absent orange 3095 12379 62 14.2 0.91

* The catalyst was calcined at a temperature of 871 °C.

† The polymerization reaction was carried out at 100°C in the presence of 5 ml 1-hexene.

Table II. Examples 9-20 according to the present invention, in which Cr/silicon dioxide-titanium dioxide with light reduction is used

Example Reducing agent Processing Color Performance
(g PE/g catalyst) Activity
(g/g/hour) HLMI
(g/10 min) I ₁₀
(g/10
min) MI
(g/10
min) 9 10 psig (approximately 69 kPa) ethylene sunlight, 10 min blue/gray 2980 5430 88 23.1 1.72 10 12 psig (approximately 83 kPa) ethylene sunlight, 4 hours blue/gray 2231 2434 71 17.6 1.38 11 12 psig (approximately 83 kPa) ethylene sunlight, 4 hours blue/gray 2443 3858 57 14.6 1.10 12 10 psig (approximately 69 kPa) ethylene (× 2) sunlight 6 hours, 3 hours blue/gray 2212 2328 30 7.1 0.50 13 10 psig (approximately 69 kPa) methane sunlight, 10 min green 2915 6780 114 26.3 1.95 14 10 psig (approximately 69 kPa) methane sunlight, 6 hours green 3099 5469 70 16.7 1.17 15 10 psig (approximately 69 kPa) freon sunlight, 2 hours green 1554 1636 29 7.1 0.54 16 10 psig (approximately 69 kPa) freon sunlight, 2 hours green 2820 1945 29 7.0 0.55 17 4 drops of benzene sunlight 15 min red/purple 3951 5268 89 20.8 1.46 18 ^* 10 psig (approx. 69 kPa) _H2 sunlight, 15 min green 3297 2953 52 11.9 0.88 19 ^* 10 psig (approx. 69 kPa) _H2 sunlight 2 hours grey/green 3437 3124 31 7.3 0.50 20 ^*† 10 psig (approximately 69 kPa) methane Sunlight 6 hours green 3239 14951 67 14.7 0.92

* The catalyst was calcined at a temperature of 871 °C.

† The polymerization reaction was carried out at 100°C in the presence of 5 ml 1-hexene.

EXAMPLES 21-26

In Examples 21-26, a Cr/silica catalyst containing hexavalent chromium compounds (1.0 wt.%) was used as a supported catalyst. The Cr/silica catalysts were calcined at 650°C in dry air (oxidizing atmosphere) to convert the chromium to the hexavalent oxidation state. The Cr/silica catalyst had a BET surface area of 500 ^m2 /g, a pore volume of 1.6 ml/g, and an average particle size of 100 μm. Table III lists various catalyst reduction conditions, catalyst productivity (grams of polyethylene per gram of catalyst), catalytic activity (grams of polyethylene per gram of catalyst per hour), and HMLI, I ₁₀ , and MI (g/10 min) of the resulting polymers.

Using ethylene as the reducing agent, Examples 22-23 demonstrated catalytic activity comparable to that of Example 21, as well as an unexpected increase in melt flow potential. Also unexpectedly, catalysts prepared using methane as the reducing agent under sunlight had significantly increased catalytic activity, comparable melt flow potential in ethylene homopolymerization (Example 24), and superior melt flow potential in ethylene/1-hexene copolymerization (Example 26).

Table III. Examples of application of Cr/silicon dioxide based catalysts

Example Reducing agent Processing Color Performance
(g PE/g catalyst) Activity
(g/g/hour) HLMI
(g/10 min) I ₁₀
(g/10
min) MI
(g/10
min) 21 absent absent orange 2347 2996 4.8 0.82 0,009 22 10 psig (approximately 69 kPa) ethylene (× 2) sunlight 6 hours, 3 hours blue/gray 1409 3019 6.1 1.22 -- 23 10 psig (approximately 69 kPa) ethylene (× 2) sunlight 6 hours, 3 hours blue/gray 1814 1432 7.4 1.53 0.033 24 10 psig (approximately 69 kPa) methane sunlight, 6 hours green 2603 4222 4.0 0.66 -- 25 ^† absent absent orange 2923 5480 2.4 0.21 0 26 ^† 10 psig (approximately 69 kPa) methane sunlight, 6 hours green 3094 7140 3.6 0.60 0,014

† The polymerization reaction was carried out at 100°C in the presence of 5 ml 1-hexene.

EXAMPLES 27-29

Some of the above examples were carried out in sunlight or alternatively under a fluorescent light source emitting in the UV-visible region of the spectrum. In Example 27, to evaluate which wavelength of light may be most effective in terms of reducing hexavalent compounds, the Cr/silica-titania catalyst described above was prepared by calcining for 3 hours at 650°C and treating the calcined catalyst with a small amount (0.5 ml) of n-hexane. Samples of the catalyst in glass bottles were subjected to the reduction step as described above using one of the light emitting diodes selected from a red LED (631 nm), a blue LED (450 nm) or a violet LED (392 nm). The intensity and wavelength distribution of each light source are shown in Fig. 2 . The color of each sample was monitored as an indication of the progress and efficiency of the reduction step. Of the three LEDs listed, blue light was by far the most effective, while red light produced almost no results. Violet light was also effective, but somewhat less so than blue light. Since these experiments were conducted in glass containers, which can absorb the shortest wavelengths of visible light, it is believed that a significant portion of the light emitted by the violet LED may have been absorbed by the glass.

In Example 28, IR reflectance spectra were measured for the Cr/silica sample prepared as described above in Examples 21-26. As shown in Fig. 3 , said spectra show a strong absorption at about 600 nm, attributed to Cr(III) compounds, and another absorption band at about 340 nm, attributed to Cr(VI) compounds. Thus, without wishing to be bound by theory, a more efficient light source for catalyst reduction should include wavelengths less than 500 nm (e.g., comparing blue light with red light in Fig. 2 ).

In Example 29, perfluorohexane was evaluated as a reducing agent in a manner similar to that used for the evaluation of benzene (Example 17), but the use of perfluorohexane did not result in a color change. Perfluorohexane contains only C-F and C-C bonds. Without wishing to be bound by theory, it is believed that compounds with C-H bonds are more susceptible to oxidation under irradiation conditions.

EXAMPLES 30-45

Examples 30-45 were carried out in the same manner as Examples 1-20 and, with the exception of Examples 36 and 42, used the same supported chromium catalyst comprising silica-titania (2.5 wt.% Ti and 1.0 wt.% Cr). The Cr/silica-titania catalysts were calcined at 871°C in dry air. Examples 36 and 42 used a 10% Cr/silica catalyst that was calcined at 400°C in dry air for 3 hours. In Examples 30-45, the catalyst weight was from 0.04 to 0.26 grams and the polymerization reaction time was from 30 to 240 hours. Table IV shows the various catalyst reduction conditions, catalytic activity, polymer molecular weight parameters, polymer rheological characteristics, and polymer MI, I ₁₀ , and HLMI (g/10 min).

Molecular weights and molecular weight distributions were determined using a PL-GPC 220 system (Polymer Labs, Agilent Company) equipped with an IR4 detector (Polymer Char, Spain) and three Styragel HMW-6E GPC columns (Waters, MA) operated at 145 °C. The flow rate of the mobile phase 1,2,4-trichlorobenzene (TCB) containing 0.5 g/L 2,6-di-tert-butyl-4-methylphenol (BHT) was set at 1 mL/min, with polymer solution concentrations ranging from 1.0 to 1.5 mg/mL depending on molecular weight. Sample preparation was carried out at 150 °C for nominally 4 h with occasional gentle mixing, after which the solutions were transferred to sample injection vials. A sample volume of approximately 200 μL was used. An integrated calibration method was used to determine the molecular weights and molecular weight distributions using MARLEX® BHB5003 high-density polyethylene (HDPE) resin from Chevron Phillips Chemical Company as a broad molecular weight distribution standard. A table of integrated values for the broad molecular weight distribution standard was previously generated in a separate SEC-MALS experiment. Mn is the number average molecular weight, Mw is the weight average molecular weight, Mz is the z-average molecular weight, Mv is the viscosity average molecular weight, and Mp is the maximum molecular weight (the position of the maximum point of the molecular weight distribution curve on the molecular weight axis).

The rheological properties of the melt were determined as follows. The oscillatory shear measurements at low strain (10%) were performed on an Anton Paar MCR 501 rheometer using parallel plate geometry. All rheological tests were performed at 190°C. The data were then substituted into the complex viscosity curve |ƞ * | versus frequency (ω) using a modified three-parameter empirical Carreau-Yasuda (CY) model to obtain the zero-shear viscosity value - ƞ ₀ , the characteristic viscous relaxation time - τ _ƞ and the rheological width parameter - a (CY-a parameter). The simplified empirical Carreau-Yasuda (CY) model is presented as follows.

$$|\eta *(\omega )|=\frac{\eta 0}{{[1+{(\tau \eta \omega )}^a]}^{(1-n)/a}}$$

where: | ƞ* ( ω ) | = value of complex shear viscosity;

ƞ ₀ = zero shear viscosity;

τ _ƞ = viscous relaxation time (Tau(η) in sec);

a = “rheological width” parameter (CY-a parameter);

n = adjusts the final slope of the power function, given by 2/11; and

ω = angular frequency of deformation under oscillatory shear.

A detailed description of the significance and explanation of the CY model and the parameters derived from it can be found in: C. A. Hieber and H. H. Chiang, Rheol. Acta , 28, 321 (1989); C. A. Hieber and H. H. Chiang, Polym. Eng. Sci. , 32, 931 (1992); and R. B. Bird, R. C. Armstrong, and O. Hasseger, Dynamics of Polymeric Liquids, Volume 1, Fluid Mechanics , 2nd Edition, John Wiley & Sons (1987); each of which is incorporated herein by reference in its entirety.

The number of long chain branches (LCBs) per 1,000,000 total carbon atoms of the polymer as a whole was calculated using the method of Janzen and Colby (J. Mol. Struct., 485/486, 569-584 (1999), incorporated herein by reference in its entirety) based on zero shear viscosity values (determined based on the Carreau-Yasuda (CY) model) and measured Mw values obtained with a Dawn EOS multi-angle light scattering detector (Wyatt).

As shown in Table IV, the light reduction step was unexpectedly effective with several different hydrocarbon reducing agents: methane, ethane, n-pentane, n-hexane, toluene, decalin, adamantane, and cyclohexane. Example 34 (34 min) and Example 35 (91 min) used different polymerization times, as did Example 43 (61 min) and Example 44 (37 min). With the exception of Examples 36 and 42, the catalysts had unexpected catalytic activity and melt flow potential. Examples 30-33 in Table IV demonstrated that treating the catalyst by irradiating it with light in the presence of a reducing agent reduced the long chain branching content of the resulting polymer while unexpectedly increasing the CY-a parameter.

Figure 4 shows the molecular weight distributions of the polymers prepared according to Examples 36, 40, and 42. As shown in Table IV and Figure 4 , the polymers prepared according to Example 36 (0.26 g catalyst, reaction time 151 min) and according to Example 42 (0.2 g catalyst, reaction time 240 min) unexpectedly had very broad molecular weight distributions (Mw/Mn in the range from 50 to 90) combined with relatively high CY-a values (from 0.29 to 0.33) and very low LCBs levels (less than 3 LCBs per million total carbon atoms). Also unexpectedly, the results shown in Table IV and Figure 4 demonstrated that the polymer prepared according to Example 40 (0.057 g catalyst, reaction time 57 min) had a long high molecular weight tail, resulting in an Mz/Mw value of 45 to 50, despite having a relatively narrow molecular weight distribution (Mw/Mn less than 10) and essentially no LCBs.

Table IV. Examples 30-45

Example Reducing agent Processing Color Performance
(g PE/g catalyst) Activity
(g/g/
hour) HLMI
(G/
10 min) I ₁₀
(G/
10 min) MI
(G/
10 min) CY-a 30 absent absent - - - - - 4.45 0.199 31 absent absent - - - - - 0.16 0.193 32 n-pentane Sunlight
1 hour blue/gray 3188 3298 154 36.4 3.65 0.226 33 n-hexane White light
3 hours blue/gray 2251 2936 139 32.8 3.22 0.219 34 toluene Blue light
1.5 hours blue/black 1481 3065 203 46.8 3.6 0.199 35 toluene Blue light
1.5 hours blue/black 4235 3434 67 15.2 1,1 0.201 36 n-pentane UV radiation
3 hours black 238 107 3.4 0.5 - 0.294 37 10 psig (approximately 69 kPa) ethane UV radiation
4 hours dark blue/gray 2267 2616 113 26.8 2.1 0.196 38 toluene Blue light
2.5 hours black 2312 2070 153 33.4 2.9 0.205 39 decalin Blue light
2 hours blue 1954 2345 198 34.7 4.2 0.204 40 adamantane Blue light
2 hours blue 2205 2646 166 30.6 3.5 0,200 41 cyclohexane Blue light
2 hours blue 2423 1069 47 7.3 0.8 0,210 42 absent absent dark red 262 81 0.5 - - 0.327 43 methane Blue light
2 hours green 2692 2884 157 36.5 3.4 0.229 44 methane Blue light
2 hours blue/gray 1024 1920 82 18.6 1.5 0.174 45 absent absent orange 2668 2541 220 51.7 4.6 0.219

Table IV. Examples 30-45 (continued)

Example Reducing agent Mn
(kg/mol) Mw
(kg/mol) Mz
(kg/mol) Mw/Mn Mz/Mw η ₀
(Pa-sec) τ _ƞ
(sec) JC LCB
(per million C) 30 absent - - - - - - - - 31 absent - - - - - - - - 32 n-pentane 14.7 100 579 6.8 5.8 9.68E+03 0,016 8.8 33 n-hexane 9.8 102 962 10.3 9.5 1.24E+04 0.022 9.9 34 toluene 11.1 107 1060 9.6 9.9 1.24E+04 0,020 7.8 35 toluene 14.3 142 1129 9.9 8.0 4.42E+04 0.081 6.4 36 n-pentane 8.3 416 2810 50.3 6.8 4.11E+06 50.4 2,2 37 ethane 9.6 120 1159 12.5 9.6 2.29E+04 0.034 7.7 38 toluene 14.7 101 760 6.9 7.5 1.26E+04 0,020 10.3 39 decalin 14.4 108 835 7.5 7.7 9.74E+03 0,014 5.9 40 adamantane 17.2 166 8076 9.6 48.6 1.20E+04 0,015 <0.01 41 cyclohexane 15.7 162 1453 10.4 9.0 5.23E+04 0,111 4.2 42 absent 6.3 557 3342 88.5 6.0 7.01E+06 49.6 1,2 43 methane 13.8 104 726 7.5 7.0 8.20E+03 0,014 6.2 44 methane 14.3 130 1165 9.1 9.0 3.31E+04 0.024 7.4 45 absent 12.9 102 843 7.9 8.3 8.01E+03 0,013 6.6

EXAMPLES 46-52

Examples 46-52 were carried out to determine the degree of reduction of hexavalent chromium and the average valence after reduction of a typical supported chromium catalyst. The results are shown in Table V. Sample 52 was a chromium/silica-titania catalyst containing approximately 0.8 wt. % chromium and 7 wt. % titania and having a BET surface area of 530 ^m2 /g, a pore volume of 2.6 ml/g and an average particle size of 130 μm, which was calcined in dry air at 850°C for 3 hours to convert the chromium to the hexavalent oxidation state (orange color). This procedure converted more than 86 wt. % of the chromium to the hexavalent state. In Examples 46-47, approximately 2 g of the catalyst samples prepared according to Example 52 were separately loaded into a glass reaction vessel and 0.5 ml of liquid isopentane was added to the vessel. In Examples 48-49, approximately 1.5 atm of methane gas (approximately 152 kPa) was pressurized into the glass bottle. The bottle was then placed in a light-tight box under a blue fluorescent light source (with an intensity approximately 2 times greater than the expected intensity of sunlight) and the bottle was continuously rotated so that all of the catalyst was exposed to the light for 24 hours. The final color of the catalyst is shown in Table V. Approximately 20 ml of a 2 M H ₂ SO ₄ solution were then added to the bottle with the catalyst. To the resulting mixture were added 5 drops of ferroin Fe(+3) indicator. Typically, this indicator turned blue-green, indicating the presence of Fe(III) ions. The solution was then titrated to the ferroin endpoint (red) using a ferric alum solution previously calibrated by reaction with standardized 0.1 M sodium dichromate. When the solution turned red, the endpoint was noted and the volume of titrant was recorded to calculate the oxidizing power of the catalyst, expressed as wt % Cr(VI) and as percent reduced chromium, i.e., the percentage of the original oxidizing power of Cr(VI) that was removed by the reduction treatment. The average valence was also calculated by multiplying the percent reduced chromium by +3 and subtracting this number from +6.

Of course, this treatment only produces a moderate oxidation state. It should be noted that although Table V gives the oxidation power as wt% Cr(VI), in reality all the chromium may be present in lower valence states such as Cr(IV) or Cr(V). Thus, the Cr(VI) value in Table V only indicates the maximum amount of Cr(VI) that may be present. It is more likely that the reduced catalysts are characterized by a combination of several valence states that produce the measured oxidation power. It should be noted that some of the reduced chromium, and in particular those catalysts reduced with CO, may be in the divalent state, which cannot be detected in the test specified, the minimum threshold for which is the trivalent state.

In Example 52, it was demonstrated that the air-calcined chromium catalyst contained substantially most of the chromium (0.69/0.80 = 86 wt.%) in the form of Cr(VI), and it is this amount of Cr(VI) that is reduced by treatment with light. This amount of Cr(VI) therefore serves as the starting amount, which had an average valence of +6, and which serves as a reference value to which the reduced catalysts are then compared. Samples 46-47 were reduced chromium catalysts with an average valence of approximately +3.3, containing no more than 0.06 wt.% Cr(VI), in which less than 10 wt.% of the starting hexavalent chromium still remained in the hexavalent oxidation state. Samples 48-49 were reduced chromium catalysts with an average valence of approximately +4.1, containing no more than 0.26 wt.% Cr(VI) and less than 40 wt.% chromium in the hexavalent oxidation state. In Examples 50-51, the catalyst was reduced in a CO atmosphere using either a blue light source or elevated temperature, resulting in an oxidizing power that was not measurable (0 wt.% Cr(VI) in the table). Thus, the average valence should be no greater than +3. However, the catalyst reduced with CO by conventional means (Example 51) is known to have a valence corresponding primarily to Cr(II), which is not detectable in such a test. Accordingly, Examples 50 and 51 are listed as having an average valence of less than or equal to +3. Notably, it is not possible to distinguish between Cr(II) and Cr(III) compounds using this test, but no measurable amount of hexavalent chromium was present in Examples 50-51.

Table V. Examples 46-52

Example Reducing agent Processing Color Catalyst
(G) Cr(VI)
(% mass) Reclaimed Chrome
(% mass) Average valence 46 isopentane blue light
24 hours blue 2.05 0.06 90.8 3.28 47 isopentane blue light
24 hours blue 2.08 0.06 90.9 3.27 48 methane blue light
24 hours olive green 2.14 0.26 62.3 4.13 49 methane blue light
24 hours olive green 2.30 0.26 61.9 4.14 50 CO blue light
2 hours celadon 2.33 0,00 100 < 3 51 CO CO2 recovery
30 min - 350 °C blue 2.52 0,00 100 < 3 52 absent absent orange - 0.69 0 6.00

The present invention has been described above with reference to numerous aspects and specific examples. In light of the above detailed description, those skilled in the art will recognize many embodiments of the invention. All such obvious embodiments are within the full intended scope of the appended claims. Other aspects of the present invention may include, but are not limited to, the following aspects (aspects are described as "comprising" but may alternatively "consist essentially of" or "consist of"):

Aspect 1. A method for reducing a chromium catalyst for the polymerization of olefins, comprising irradiating a reducing agent and a chromium catalyst on a support containing chromium in a hexavalent oxidized state, using a light beam with a wavelength in the UV-visible region of the spectrum to reduce at least a portion of the chromium catalyst on the support to obtain a reduced chromium catalyst.

Aspect 2. The method defined according to aspect 1, characterized in that said method includes irradiating a mixture of a chromium catalyst on a support and a reducing agent in a diluent at any suitable pressure.

Aspect 3. The method defined according to aspect 2, wherein the diluent comprises any suitable hydrocarbon solvent or any hydrocarbon solvent described herein, such as 1-hexene, hexane, isobutane, toluene or cyclohexene, as well as mixtures or combinations thereof.

Aspect 4. The method defined according to any of the previous aspects, wherein the supported chromium catalyst comprises any suitable solid oxide or any solid oxide described herein, such as silica, alumina, silica-alumina, silica-coated alumina, aluminum phosphate, aluminophosphate, heteropolytungstate, titanium dioxide, zirconia, magnesium oxide, boron oxide, zinc oxide, silica-titania, silica-zirconia, aluminum oxide-titanium dioxide, aluminum oxide-zirconia, zinc aluminate, aluminum oxide-boron oxide, silica-boron oxide, aluminophosphate-silica, titanium dioxide-zirconia, etc., or any combination thereof.

Aspect 5. The method defined according to any one of aspects 1-3, wherein the supported chromium catalyst comprises silica, silica-alumina, silica-coated alumina, silica-titanium dioxide, silica-titanium dioxide-magnesium oxide, silica-zirconia, silica-magnesium oxide, silica-boron oxide, aluminophosphate-silicon dioxide, etc. or any combination thereof.

Aspect 6. The method defined according to any one of aspects 1-3, wherein the supported chromium catalyst comprises chromium/silica, chromium/silica-titanium dioxide, chromium/silica-titanium dioxide-magnesium oxide, chromium/silica-alumina, chromium/alumina with a coating of silica, chromium/aluminophosphate, etc., or any combination thereof.

Aspect 7. The method defined according to any of the previous aspects, wherein said catalyst has a total pore volume in any suitable range or any range given herein, such as from about 0.5 to about 5 ml/g, from about 1 to about 5 ml/g, from about 0.9 to about 3 ml/g, from about 1.2 to about 2.5 ml/g, etc.

Aspect 8. The method defined according to any of the previous aspects, wherein said catalyst has a BET surface area in any suitable range or any range given herein, such as from about 100 to about 1000 ^m2 /g, from about 200 to about 700 ^m2 /g, from about 250 to about 600 ^m2 /g, from about 275 to about 525 ^m2 /g, etc.

Aspect 9. The method defined according to any of the previous aspects, wherein said catalyst further comprises any suitable modification or any modification described herein, for example titanated, fluorinated, sulfated, phosphated modification, etc.

Aspect 10. The method defined according to any of the previous aspects, further comprising a calcination step for obtaining a supported chromium catalyst comprising chromium in a hexavalent oxidation state, wherein the calcination comprises applying any suitable maximum temperatures and time conditions or any maximum temperatures and time conditions described herein, such as a maximum temperature of from about 300°C to about 1000°C, from about 500°C to about 900°C, from about 550°C to about 870°C, etc., for a period of time of from about 1 minute to about 24 hours, from about 1 hour to about 12 hours, from about 30 minutes to about 8 hours, etc.

Aspect 11. The method defined according to any of the previous aspects, wherein the supported chromium catalyst (or reduced chromium catalyst) comprises any suitable amount of chromium or any amount described herein, such as from about 0.01 to about 20 wt.%, from about 0.1 to about 10 wt.%, from about 0.2 to about 5 wt.%, from about 0.2 to about 2.5 wt.%, etc., based on the weight of the catalyst.

Aspect 12. The method defined according to any of the previous aspects, wherein the wavelength comprises one wavelength or a range of wavelengths in the visible spectrum.

Aspect 13. The method defined according to any of aspects 1-11, wherein the wavelength comprises one wavelength or a range of wavelengths from 200 nm to 750 nm.

Aspect 14. The method defined according to any of aspects 1-11, wherein the wavelength comprises one wavelength or a range of wavelengths from 300 to 750 nm, from 350 to 650 nm, from 300 to 500 nm or from 300 to 400 nm.

Aspect 15. The method defined according to any of aspects 1-11, wherein the wavelength comprises one wavelength or a range of wavelengths below 600 nm, below 525 nm or below 500 nm.

Aspect 16. The method defined according to any of the previous aspects, wherein the wavelength is a single wavelength.

Aspect 17. The method defined according to any of aspects 1-15, wherein the wavelength is a wavelength range comprising at least 25 nm, at least 50 nm, at least 100 nm, at least 200 nm, etc.

Aspect 18. The method defined according to any of the previous aspects, wherein the irradiating step is carried out at any suitable temperature or any temperature described herein, such as less than about 200 °C, less than about 100 °C, less than about 40 °C, from about 0 °C to about 100 °C, from about 10 °C to about 40 °C, etc.

Aspect 19. The method defined according to any of the previous aspects, wherein the irradiating step is carried out for any suitable exposure time or for any exposure time described herein, such as from about 15 seconds to about 10 hours, from about 1 minute to about 6 hours, from about 1 minute to about 15 minutes, from about 5 minutes to about 1 hour, etc.

Aspect 20. The method defined according to any of the previous aspects, wherein the light beam has any suitable intensity or intensity in any range given herein, such as at least about 500 lumens, at least about 1000 lumens, at least about 2000 lumens, at least about 5000 lumens, at least about 10000 lumens, at least about 20000 lumens, etc.

Aspect 21. The method defined according to any of the previous aspects, wherein the light beam has any suitable power or any power described herein, such as at least about 50 W, at least about 100 W, at least about 200 W, at least about 500 W, at least 1000 W, at least 2000 W, etc.

Aspect 22. The method defined according to any of the previous aspects, wherein the chromium catalyst on the support is irradiated using any suitable illumination or any illumination described herein, such as at least about 100 lux, at least about 500 lux, at least about 1000 lux, at least about 2000 lux, at least about 5000 lux, at least about 10,000 lux, at least about 20,000 lux, at least about 100,000 lux, etc.

Aspect 23. The method defined according to any of the previous aspects, wherein the proportion of chromium in the supported chromium catalyst in the hexavalent oxidation state is at least about 10 wt.%, at least about 20 wt.%, at least about 40 wt.%, at least about 60 wt.%, at least about 80 wt.%, at least about 90 wt.%, etc., and/or the proportion of chromium in the reduced chromium catalyst in the hexavalent oxidation state is less than or equal to about 75 wt.%, less than or equal to about 50 wt.%, less than or equal to about 40 wt.%, less than or equal to about 30 wt.%, etc.

Aspect 24. The method defined according to any of the previous aspects, wherein the chromium in the reduced chromium catalyst has an average valence of less than or equal to about 5.25, less than or equal to about 5, less than or equal to about 4.75, less than or equal to about 4.5, less than or equal to about 4.25, less than or equal to about 4, etc.

Aspect 25. The method defined in any of the previous aspects, wherein the reduced chromium catalyst has a catalytic activity that is greater (by any amount recited herein, such as at least 10%, at least 20%, at least 50%, etc.) than the catalytic activity of the supported chromium catalyst, under slurry polymerization conditions at a temperature of 105°C and a pressure of 550 psig (about 3.8 MPa g), and/or the reduced chromium catalyst has a catalytic activity that is greater (by any amount recited herein, such as at least 10%, at least 20%, at least 50%, etc.) than the catalytic activity of an otherwise identical catalyst prepared using the same reductant at an elevated temperature (e.g., 300 °C, 350 °C, 400 °C, 450°C or 500°C) without light irradiation, under suspension polymerization conditions at a temperature of 105°C and a pressure of 550 psig (approximately 3.8 MPa g).

Aspect 26. A reduced chromium catalyst obtained by the method according to any of the previous aspects.

Aspect 27. A catalyst production system comprising:

(a) a catalyst production vessel configured to perform a method for reducing a chromium catalyst defined according to any one of aspects 1-25;

(b) a catalyst inlet configured to introduce a slurry of supported chromium catalyst into a catalyst preparation vessel, wherein at least a portion of the chromium is in a hexavalent oxidation state; and

(c) a regenerated catalyst outlet configured to remove the regenerated chromium catalyst slurry from the catalyst production vessel.

Aspect 28. A catalyst production system comprising:

(a) a vessel for producing a catalyst, configured to irradiate a suspension of a chromium catalyst on a support in a diluent using a light beam with a wavelength in the UV-visible region of the spectrum;

(b) a catalyst inlet configured to introduce a slurry of supported chromium catalyst into a catalyst preparation vessel, wherein at least a portion of the chromium is in a hexavalent oxidation state; and

(c) a regenerated catalyst outlet configured to remove the regenerated chromium catalyst slurry from the catalyst production vessel.

Aspect 29. The system defined according to aspect 27 or 28, wherein the diluent comprises any suitable reducing agent or any reducing agent described herein, such as substituted or unsubstituted hydrocarbons, saturated or unsaturated hydrocarbons, etc.

Aspect 30. A system defined according to any of aspects 27-29, characterized in that said catalyst production system further comprises an inlet for a reducing agent configured to introduce a feed stream of reducing agent into a vessel for producing a catalyst.

Aspect 31. A system defined according to any of aspects 27-30, wherein the catalyst preparation vessel is any suitable vessel or any vessel described herein, such as a stirred tank, a flow reactor vessel, etc.

Aspect 32. A system defined according to any of aspects 27-31, characterized in that said catalyst production system is designed to operate in a periodic or continuous mode.

Aspect 33. A system defined according to any one of aspects 27-32, wherein the chromium catalyst slurry on the support is irradiated for any suitable residence time (or exposure time) or for any period of time given herein, such as from about 15 seconds to about 10 hours, from about 1 minute to about 6 hours, from about 1 minute to about 15 minutes, from about 5 minutes to about 1 hour, etc.

Aspect 34. A system defined according to any of aspects 27-33, characterized in that said catalyst production system further comprises a lamp module located inside or outside the catalyst production vessel.

Aspect 35. A system defined according to any of aspects 27-34, wherein the vessel for producing the catalyst comprises any suitable light beam source or any light beam source described herein, such as sunlight, fluorescent white light, a UV lamp, etc.

Aspect 36. A system defined according to any of aspects 27-35, characterized in that said catalyst production system further comprises a co-catalyst inlet configured to introduce a co-catalyst feed stream into a catalyst production vessel.

Aspect 37. A system defined according to any of aspects 27-36, characterized in that said catalyst production system further comprises (d) a controller configured to regulate the residence time of the chromium catalyst on the support in the catalyst production vessel, and/or the temperature of the catalyst production vessel, and/or the intensity of the light beam, and/or the wavelength of the light beam, and/or the amount of reduced chromium catalyst, and/or the molar ratio of the reducing agent to chromium.

Aspect 38. Polymerization reactor system comprising:

a catalyst production system defined according to any one of aspects 27-37; and

a reactor configured to contact the reduced chromium catalyst with an olefin monomer and an optional olefin comonomer under polymerization reaction conditions to produce an olefin polymer.

Aspect 39. A method for polymerizing olefins, comprising:

contacting the reduced chromium catalyst defined according to aspect 26 and the optional cocatalyst with the olefin monomer and the optional olefin comonomer in a polymerization reactor system under polymerization reaction conditions to produce an olefin polymer.

Aspect 40. A method for polymerizing olefins, comprising:

(I) irradiating a reducing agent and a supported chromium catalyst comprising chromium in a hexavalent oxidation state with a light beam having a wavelength in the UV-visible region of the spectrum to reduce at least a portion of the supported chromium catalyst to obtain a reduced chromium catalyst; and

(II) contacting the reduced chromium catalyst and the optional cocatalyst with the olefin monomer and the optional olefin comonomer in a polymerization reactor system under polymerization reaction conditions to produce an olefin polymer.

Aspect 41. The method for polymerizing olefins defined according to aspect 39 or 40, or the polymerization reactor system defined according to aspect 38, wherein the olefin monomer comprises any olefin monomer described herein, for example any _C2 - _C20 olefin.

Aspect 42. A method for polymerising olefins as defined in any one of aspects 39-41, or a polymerisation reactor system as defined in aspect 38, wherein the olefin monomer comprises ethylene.

Aspect 43. The method for polymerising olefins defined according to any of aspects 39-42, or the polymerisation reactor system defined according to aspect 38, wherein the olefin monomer and the optional olefin comonomer independently comprise a _C2 - _C20 alpha-olefin.

Aspect 44. A method for polymerising olefins as defined in any one of aspects 39-43, or a polymerisation reactor system as defined in aspect 38, wherein said catalyst is contacted with ethylene and an olefin comonomer comprising a _C3 - _C10 alpha-olefin.

Aspect 45. A method for polymerising olefins as defined in any one of aspects 39-44, or a polymerisation reactor system as defined in aspect 38, wherein said catalyst is contacted with ethylene and an olefin comonomer comprising 1-butene, 1-hexene, 1-octene or a mixture thereof.

Aspect 46. A method for polymerising olefins as defined in any one of aspects 39-41, or a polymerisation reactor system as defined in aspect 38, wherein the olefin monomer comprises propylene.

Aspect 47. A method for polymerising olefins as defined in any one of aspects 39-46, or a polymerisation reactor system as defined in aspect 38, wherein said polymerisation reactor system comprises a batch reactor, a slurry reactor, a gas phase reactor, a solution reactor, a high pressure reactor, a tubular reactor, an autoclave reactor or a combination thereof.

Aspect 48. A method for polymerising olefins as defined in any one of aspects 39-47, or a polymerisation reactor system as defined in aspect 38, wherein said polymerisation reactor system comprises a slurry reactor, a gas phase reactor, a solution reactor or a combination thereof.

Aspect 49. A method for polymerising olefins as defined in any one of aspects 39-48, or a polymerisation reactor system as defined in aspect 38, wherein said polymerisation reactor system comprises a loop slurry reactor.

Aspect 50. A method for polymerising olefins as defined in any one of aspects 39-49, or a polymerisation reactor system as defined in aspect 38, wherein said polymerisation reactor system comprises one reactor.

Aspect 51. A method for polymerising olefins as defined in any one of aspects 39-49, or a polymerisation reactor system as defined in aspect 38, wherein said polymerisation reactor system comprises two reactors.

Aspect 52. A method for polymerizing olefins defined according to any of aspects 39-49, or a polymerization reactor system defined according to aspect 38, wherein the polymerization reactor system comprises more than two reactors.

Aspect 53. A method for polymerizing olefins defined according to any of aspects 39-52, or a polymerization reactor system defined according to aspect 38, wherein the olefin polymer comprises any olefin polymer described herein.

Aspect 54. A method for polymerising olefins as defined according to any of aspects 39-45 or 47-53, or a polymerisation reactor system as defined according to aspect 38, wherein the olefin polymer comprises an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer and/or an ethylene/1-octene copolymer.

Aspect 55. A method for polymerising olefins as defined in any of aspects 39-41 or 46-53, or a polymerisation reactor system as defined in aspect 38, wherein the olefin polymer comprises a polypropylene homopolymer and/or a propylene-based copolymer.

Aspect 56. A method for polymerizing olefins defined according to any of aspects 39-55, or a polymerization reactor system defined according to aspect 38, wherein the polymerization conditions comprise a polymerization reaction temperature in the range of from about 60 °C to about 120 °C and a polymerization reaction pressure in the range of from about 200 to about 1000 psig (from about 1.4 to about 6.9 MPa).

Aspect 57. A method for polymerising olefins as defined in any of aspects 39-56, or a polymerisation reactor system as defined in aspect 38, wherein the polymerisation conditions are substantially constant, for example for a particular grade of polymer.

Aspect 58. A method for polymerizing olefins defined according to any of aspects 39-57, wherein no hydrogen is added to the polymerization reactor system.

Aspect 59. A method for polymerizing olefins as defined in any one of aspects 39-57, wherein hydrogen is added to the polymerization reactor system.

Aspect 60. A method for polymerizing olefins defined according to any of aspects 39-59, wherein the wavelength comprises one wavelength or a range of wavelengths in the visible region of the spectrum (from 380 nm to 780 nm).

Aspect 61. A method for polymerizing olefins defined according to any of aspects 39-59, wherein the wavelength comprises a single wavelength or a range of wavelengths from 200 nm to 750 nm.

Aspect 62. A method for polymerizing olefins defined according to any of aspects 39-59, wherein the wavelength comprises one wavelength or a range of wavelengths from 300 to 750 nm, from 350 to 650 nm, from 300 to 500 nm, from 300 to 400 nm.

Aspect 63. A method for polymerizing olefins defined according to any of aspects 39-59, wherein the wavelength comprises one wavelength or a range of wavelengths below 600 nm, below 525 nm, or below 500 nm.

Aspect 64. A method for polymerizing olefins defined according to any of aspects 39-63, wherein the wavelength is a single wavelength.

Aspect 65. A method for polymerizing olefins defined according to any of aspects 39-63, wherein the wavelength is a wavelength range comprising at least 25 nm, at least 50 nm, at least 100 nm, at least 200 nm, etc.

Aspect 66. A method for polymerizing olefins defined according to any of aspects 39-65, wherein the number average molecular weight (Mn) of the olefin polymer is in any range given herein, such as from about 5000 to about 150000 g/mol, from about 5000 to about 50000 g/mol, from about 10000 to about 100000 g/mol, etc.

Aspect 67. A method for polymerizing olefins defined according to any of aspects 39-66, wherein the weight average molecular weight (Mw) of the olefin polymer is in any range given herein, such as from about 50,000 to about 700,000 g/mol, from about 75,000 to about 500,000 g/mol, from about 100,000 to about 400,000 g/mol, etc.

Aspect 68. A method for polymerizing olefins defined according to any of aspects 39-67, wherein the density of the olefin polymer is in any range given herein, such as from about 0.89 to about 0.96 g/ ^cm3 , from about 0.91 to about 0.95 g/ ^cm3 , from about 0.91 to about 0.94 g/ ^cm3 , etc.

Aspect 69. A method for polymerizing olefins defined according to any one of aspects 39-68, wherein the melt flow index (MI) of the olefin polymer is in any range given herein, such as from 0 to about 25 g/10 min, from 0 to about 5 g/10 min, from 0 to about 1 g/10 min, etc.

Aspect 70. A method for polymerizing olefins defined according to any one of aspects 39-69, wherein the high load melt index (HLMI) of the olefin polymer is in any range given herein, such as from 0 to about 150 g/10 min, from about 2 to about 120 g/10 min, from about 4 to about 50 g/10 min, etc.

Aspect 71. A method for polymerising olefins as defined in any one of aspects 39-70, wherein the MI (or HLMI) of the olefin polymer obtained by the inventive method is greater than 50%, greater than 80%, greater than 100%, greater than 120%, greater than 150%, etc. of the MI (or HLMI) of an olefin polymer obtained using a supported chromium catalyst (without an irradiation step) and/or an olefin polymer obtained using an otherwise identical catalyst obtained using the same reducing agent at an elevated temperature (e.g. 300°C, 350°C, 400°C, 450°C or 500°C) without light irradiation under the same polymerisation conditions.

Aspect 72. An olefin polymer obtained by the olefin polymerization process defined according to any of aspects 39-71.

Aspect 73. An article of industrial manufacture containing an olefin polymer defined according to aspect 72.

Aspect 74. A method, system or process defined according to any of aspects 1-25 or 27-71, wherein the reducing agent comprises a compound with a C-H bond or an H-H bond.

Aspect 75. The method, system or process defined according to aspect 74, wherein the reducing agent comprises a compound with a C-H bond.

Aspect 76. A method, system or process defined according to aspect 74 or 75, wherein the reducing agent comprises a compound with a C-C bond.

Aspect 77. The method, system or process defined according to aspect 74, wherein the reducing agent comprises H ₂ .

Aspect 78. The method, system or process defined according to aspect 74, wherein the reducing agent comprises an alkane, an olefin, an aromatic compound or any combination thereof (e.g., a _C1 - _C36 alkane, olefin and/or aromatic compound; a _C1 - _C18 alkane, olefin and/or aromatic compound; a _C1 - _C12 alkane, olefin and/or aromatic compound; or a _C1 - _C8 alkane, olefin and/or aromatic compound); alternatively, the reducing agent comprises a linear, branched or cyclic alkane compound containing up to 18 carbon atoms; or alternatively, the reducing agent comprises a hydrocarbon aromatic compound containing up to 18 carbon atoms.

Aspect 79. The method, system or process defined according to aspect 74, wherein the reducing agent comprises ethylene, 1-butene, 1-hexene, 1-octene, methane, ethane, propane, isobutane, n-pentane, isopentane, n-hexane, tetrafluoroethane, cyclohexane, adamantane, decalin, benzene, toluene, etc. or any combination thereof.

Aspect 80. A method, system or process defined according to any of aspects 1-25, 27-71 or 74-79, wherein the molar ratio of reducing agent to chromium is in any suitable range or any range given herein, such as at least about 0.25:1, at least about 0.5:1, at least about 1:1, at least about 10:1, at least about 100:1, at least about 1000:1, at least about 10000:1, etc.

Aspect 81. A polymer of ethylene having (or characterized by):

Mw/Mn ratio in the range of about 30 to about 110;

a Mz/Mw ratio in the range of from about 4 to about 10; and

CY-a parameter in the range from about 0.2 to about 0.4.

Aspect 82. The polymer defined according to aspect 81, characterized in that the Mw/Mn ratio is in any range given herein, for example from about 35 to about 105, from about 40 to about 100, from about 45 to about 95, or from about 50 to about 90.

Aspect 83. A polymer defined according to aspect 81 or 82, characterized in that the ratio Mz/Mw is in any range given herein, for example from about 5 to about 9, from about 5 to about 8, from about 5.5 to about 7.5, or from about 6 to about 7.

Aspect 84. A polymer defined according to any of aspects 81-83, characterized in that the parameter CY-a is in any range given herein, for example from about 0.23 to about 0.38, from about 0.25 to about 0.35, or from about 0.27 to about 0.34.

Aspect 85. A polymer defined according to any of aspects 81-84, characterized in that the ethylene polymer has a Mn in any range given herein, such as from about 3000 to about 12000 g/mol, from about 4000 to about 11000 g/mol, from about 4000 to about 10000 g/mol, from about 5000 to about 10000 g/mol, or from about 5500 to about 9500 g/mol.

Aspect 86. A polymer defined according to any of aspects 81-85, characterized in that the ethylene polymer has a Mw in any range given herein, such as from about 250,000 to about 700,000 g/mol, from about 300,000 to about 675,000 g/mol, from about 350,000 to about 625,000 g/mol, or from about 375,000 to about 600,000 g/mol.

Aspect 87. A polymer defined according to any of aspects 81-86, characterized in that the ethylene polymer contains long chain branches (LCBs) in an amount lying in any range given herein, for example from about 0.5 to about 4, from about 0.5 to about 3, from about 0.7 to about 2.8, or from about 1 to about 2.5 LCBs per million of total carbon atoms.

Aspect 88. A polymer defined according to any of aspects 81-87, characterized in that the ethylene polymer has an HLMI in any range given herein, such as less than or about 10, less than or about 8, less than or about 5, or less than or about 4 g/10 min.

Aspect 89. A polymer of ethylene having (or characterized by):

Mw/Mn ratio in the range of from about 6 to about 15;

a Mz/Mw ratio in the range of from about 30 to about 70; and

melt flow rate in the range of from about 0.5 to about 10 g/10 min.

Aspect 90. The polymer defined according to aspect 89, characterized in that the Mw/Mn ratio is in any range given herein, for example from about 7 to about 14, from about 8 to about 13, from about 8 to about 12, or from about 9 to about 10.

Aspect 91. A polymer defined according to aspect 89 or 90, characterized in that the ratio Mz/Mw is in any range given herein, for example from about 35 to about 65, from about 40 to about 60, from about 45 to about 55, or from about 47 to about 51.

Aspect 92. A polymer defined according to any of aspects 89-91, characterized in that the melt flow index is in any range given herein, for example from about 0.5 to about 5, from about 0.7 to about 7, or from about 1 to about 5 g/10 minutes.

Aspect 93. A polymer defined according to any of aspects 89-92, characterized in that the ethylene polymer has a Mn in any range given herein, such as from about 10,000 to about 25,000 g/mol, from about 13,000 to about 22,000 g/mol, from about 15,000 to about 20,000 g/mol, or from about 16,000 to about 18,000 g/mol.

Aspect 94. A polymer defined according to any of aspects 89-93, characterized in that the ethylene polymer has a Mw in any range given herein, such as from about 100,000 to about 400,000 g/mol, from about 100,000 to about 300,000 g/mol, from about 110,000 to about 250,000 g/mol, or from about 140,000 to about 200,000 g/mol.

Aspect 95. A polymer defined according to any of aspects 89-94, characterized in that the ethylene polymer contains long chain branches (LCBs) in an amount lying in any range given herein, for example, less than or about 2, less than or about 1, less than or about 0.8, less than or about 0.5, or less than or about 0.2 LCBs per million total carbon atoms.

Aspect 96. The manufactured article comprises a polymer defined according to any of aspects 81-95.

Claims (17)

1. An ethylene copolymer intended for the formation of industrial products, having: Mw/Mn ratio in the range from 50 to 90; Mz/Mw ratio in the range from 4 to 10; and parameter CY-a in the range from 0.2 to 0.4, found on the basis of rheological measurements carried out at 190°C; and from 0.5 to 4 long-chain branches per million total carbon atoms. 2. The copolymer according to claim 1, characterized in that the ratio Mz/Mw is from 5 to 9, from 5 to 8, from 5.5 to 7.5, or from 6 to 7. 3. A copolymer according to claim 1 or 2, characterized in that the parameter CY-a has a value in the range from 0.23 to 0.38, from 0.25 to 0.35, or from 0.27 to 0.34. 4. A copolymer according to any one of paragraphs. 1-3, characterized in that this ethylene copolymer has an Mn of from 3000 to 12000 g/mol, from 4000 to 11000 g/mol, from 4000 to 10000 g/mol, from 5000 to 10000 g/mol, or from 5500 to 9500 g/mol. 5. A copolymer according to any one of paragraphs 1-4, characterized in that this ethylene copolymer has an Mw of from 250,000 to 700,000 g/mol, from 300,000 to 675,000 g/mol, from 350,000 to 625,000 g/mol, or from 375,000 to 600,000 g/mol. 6. A copolymer according to any one of claims 1 to 5, characterized in that the ethylene copolymer has a number of long chain branches (LCBs) of from 0.5 to 3, from 0.7 to 2.8, or from 1 to 2.5 LCBs per million of all carbon atoms. 7. The copolymer of any one of claims 1 to 6, wherein the ethylene copolymer has a high load melt index (HLMI) of less than or equal to 10 g/10 min, less than or equal to 8 g/10 min, less than or equal to 5 g/10 min, or less than or equal to 4 g/10 min, wherein the HLMI is determined according to ASTM D1238 at 190°C with a load of 21.6 kg. 8. The copolymer according to claim 1, characterized in that the ethylene polymer has: HLMI less than or equal to 10 g/10 min, where HLMI is determined according to ASTM D1238 at 190°C with a load of 21.6 kg; Mn in the range from 3000 to 12000 g/mol; Mw in the range from 250,000 to 700,000 g/mol; and from 0.5 to 4 long-chain branches per million total carbon atoms. 9. A copolymer according to any one of claims 1 to 8, characterized in that the ethylene copolymer comprises an ethylene/1-butene copolymer and/or an ethylene/1-hexene copolymer and/or an ethylene/1-octene copolymer.