NO762686L - - Google Patents

Description

Catalyst components and catalysis

tors for the polymerization of olefins

The present invention relates to catalyst components for the polymerization of olefins, a method for. production of these components, the catalysts produced and their use in the polymerisation of α-oleins with the general formula CH2=CHRX where 'RX denotes alkyl with 1-4 carbon atoms, or polymerisation of mixtures of these with ethylene.

Italian patent 558,925 discloses catalysts for the polymerization of olefins, produced from a reduction product of TiCl3 with alkyl aluminum halides and from an organometallic aluminum compound. The reaction between TiCl4 and the alkylaluminum halide is regulated so that a product is obtained in which titanium is essentially present in trivalent form.

It is also known that for the production of catalysts with high activity and stereospecificity for the polymerization of propylene and other similar α-olefins, the TiCl3 found in the reaction product must be present in crystalline A. form.

The A-crystalline form of TiC₂ can be obtained directly already by the reduction of TiCl₂, e.g. by using AlEtCl2 as a reducing agent and reacting at relatively low temperatures, or by heating at over 130° C the reduction product where TiCl^ is present in (3-form.

Although the specific surface area for catalyst components containing A-TiCl3 is very large (80 - 100 m<2>/g), the activity of the produced catalysts is not particularly satisfactory.

This poor activity has been attributed to the presence of aluminum compounds such as aluminum alkyl dihalides in the reduction product.

To avoid this disadvantage, it is proposed to treat the reduction product with Lewis bases, e.g. with ether (US patent 3,825,524 and British patent 1,139,450).

In the US patent, the treatment with a Lewis base is carried out preferably on TiCl3 which is in crystalline A form.

When the treatment is carried out with TiCl₂ in crystalline 3-form or when TiC₂ is already present in A-form but has not been activated by heating at 140 - 150° C, the stereospecificity of the catalyst is not very high.

In general, TiCl^ reduction products containing TiCl3 in A. form and treated with ethers have the following composition:

where: R calculates a hydrocarbon residue, X denotes halogen, m denotes a number between 0 and 2, a denotes the number of moles of aluminum compound per mol TiCl^ and is a number below 0.3,

A denotes an ether and

p indicates the number of moles of ether per mol TiCl3 and is a number greater than 0.001.

The specific surface for these products is generally over 50 - 60 m 2 /g and the porosity greater than 0.1 cm<3>/g.

Recently, it has been proposed to treat reduction products of TiCl^ with alkyl aluminum halides with both ethers and with TiCl^ (Italian patent 950 400).. Catalysts prepared from these catalyst components prove to have good activity and stereospecificity.

In order to achieve a good catalyst effect, it is crucial. that the catalyst components have a surface area greater than 75 m 2 /g and a porosity greater than 0.15 cm 3 /g, and that TiCl^ is present in crystalline A form.

Contrary to what one would expect, it has surprisingly been shown that it is possible to prepare catalysts with good activity and high stereospecific ability for the polymerization of CH-,=CR-α-olefins (R denotes an alkyl radical with 1-4 carbon atoms) based on TiCl^ reduction products with halogenated metal-organic aluminum compounds that have been treated in a suitable manner, even if these products have a surface area (specific surface) of substantially less than 75 m 2 /g, a lower porosity than 0.15 cm 3 /g and under X-ray irradiation gives a spectrum which shows the main lines characteristic of TiCl-j in crystalline 3_form.

Such catalyst components containing TiCl-^ are characterized by the presence of the following lines in their X-ray spectrum with the indicated lattice spacings: d = 5.4 Å

(strong line), d = 2.75 Å (medium strong line) and d = 2.12 Å

(medium weak line), d = 1.98 Å (very weak line) and d = 1.77 Å (medium strong line).

The first four lines are characteristic of TiCl^i 3-form, line d =1.77 Å characterizes together with the other lines the new crystalline form of TiCl-^.

The complete X-ray spectrum for TiCl3-3 is described by Natta and co-workers in "Atti Accademia dei Lincei" 24, 8 121 - 129 (1958).

The catalyst components according to the invention consist of or contain products with the following composition:

where R denotes a hydrocarbon residue with 1-20, preferably 2-10 carbon atoms, in particular alkyl, aryl, cycloalkyl, alkylaryl or aralkyl, m greater than or equal to zero less than or equal to 2.5,

x denotes halogen,

a is a number below 0.4 but preferably below 0.2,

A denotes 1 mol. monoether or polyether which with aluminum or alkylaluminum can form coordination complexes or compounds which are soluble in at least one solvent selected from the monoether itself and polyether, aromatic and aliphatic hydrocarbons and their halogenated derivatives,

p is equal to or greater than 0 and less than 0.5, generally between 0.001 and 0.5.

The specific surface area for catalyst components according to the invention is between 1 and 50 m 2 /g, in particular between 2 and 20 m 2 /g, the porosity is below 0.1 cm 3 /g and more particularly

between 0.05 and 0.001 cm<3>/g.

The surprising feature of these catalyst components consists in the fact that catalysts prepared from them promote a stereoregular or ethereospecific polymerization of α-olefins (especially propylene), despite the fact that their X-ray spectrum shows the characteristic lines of (B-TiC^ which so far determined not has been considered suitable for stereoregular polymerization of α-olefins Catalysts prepared from the present catalyst components have, in addition to great stereospecificity, also high activity.

The production of these catalyst components can take place by means of a method which also constitutes a side of the invention, and which uses the following steps in the order indicated: 1) reduction of TiCl^ with an aluminium-organometallic preparation bond with the formula Al R<X>2, Al R2X or A12r'3X3, where R and X have the previously indicated meanings, 2) optionally but not necessarily prior heat treatment of the reduction product at a temperature between 20 and 100° C over a period of time which depends on the temperature and which is between 10 minutes and 5 hours, 3) treatment of the reduction product with a monoether or polyether as previously defined, at a temperature of between 70 and 120° C and finally 4) washing the product from step 3) with an inert hydrocarbon.

Between steps 2 and 3, it sometimes proves advantageous to carry out an intermediate operation in which a certain amount of aluminum alkyl compound, e.g. A1(C2H^)2C1 and then propylene (or other olefins) is added

(0.2 - lg propylene per g catalyst complex). This treatment improves the grain size and volume weight of the polymer.

First step (reduction of TiCl^)

TiCl^ is reduced with aluminium-organic compounds of the formula A1RX2/A1R2X or A12<R>3<X>3, where R denotes a hydrocarbon residue with 2 to 10 carbon atoms, with in particular an alkyl group such as ethyl, propyl, butyl, etc. and where X denotes halogen, preferably chlorine. Examples of typical aluminum compounds are: A1C2H5C12, A1C3H7C12, AI2(C2H5)3<C1>3, Al2 (C3H?) 3C13, A1(C2H5)2C1 and Sl (C-jH-,) 2C1. The reduction of TiCl3 is advantageously carried out in a liquid hydrocarbon under the reaction conditions. The reduction temperature depends on the selected type of metal-organic aluminum compound as reducing agent.

For aluminum alkyl sesquichlorides or monochlorides a temperature of -10 to +20° C is preferably used, especially between 0 and +10° C, for aluminum alkyl dichlorides temperatures between 0 and 40° C are preferred, and preferably between 10 and 30° C.

The ratio Al/Ti varies between 0.1 and 5, preferably between 0.5 and 2.

At the end of the reaction, the solid can be separated from

the liquid phase and washed with a hydrocarbon solvent.

The solid product generally contains per mol TiCl3 from 0.1 to 1 mol organometallic aluminum compound.

2 net steps (temperature pretreatment)

The reduced substance can be pretreated at 20 to 100° C., preferably 60 to 90° C. This thermal pretreatment usually occurs by keeping the reduced solid in suspension in a hydrocarbon solvent, preferably of the same type used during the reduction step.

At the end of pretreatment, the compound can be washed several times with hydrocarbon.

3rd step (treatment with ethers)

The reduced solid, which is optionally heat-pretreated in the second step, is reacted with either a monoether or a polyether such as with aluminum or aluminum alkyl halides which form coordination complexes or compounds which are soluble in at least one of the following solvents: the monoether or the polyether itself , aromatic or aliphatic hydrocarbons and their halogenated derivatives. One can use all monoethers or polyethers which can form coordination ion complexes or compounds which have specified solubility properties, with aluminum or aluminum alkyl halides. More particularly, one can choose the ethers from among monoethers with the formula R'OR" where R<1> and R" can be the same or different, denote alkyl groups with 1 to 10, and preferably 4 - 6 carbon atoms, aryl groups, cycloalkyl groups, alkylaryl groups due to aralkyl groups, or chosen from among poly- . ethers such as diethylene glycol dimethyl ether, 1,2-diphenoxyethane and the like. Particularly interesting results are obtained with di-n-butyl ether and di-isoamyl ether.

The ether/Ti molar ratio is generally between 0.5 and 2.5, more particularly between 0.8 and 1.5. The turnover temperature is between 70 and 120° C, preferably - .80 to 100° C.

The catalysts produced by bringing the solid catalyst components according to the invention into contact with organometallic aluminum compounds such as aluminum trialkyls or their complexes or alkylaluminum halides such as dialkylaluminum chlorides and alkylaluminum sesquichloride, can be used for the polymerization of olefins in general and in particular for the stereospecific polymerization of CH2=CHR X (R x denotes alkyl with 1 - 4 carbon atoms) such as, for example: propylene, butene-1, 4-methylpentene-1 and their mixtures, and/or mixed with ethylene, forming crystalline polymers and copolymers.

Catalysts prepared from alkyl aluminum halides and especially from aluminum alkyl monohalides are suitable for the polymerization of propylene and its mixtures with ethylene due to the fact that the polymer is prepared with a high isptactic index (wt% polymer insoluble in boiling n-heptane).

In the polymerization of ethylene and propylene, the ethylene content in the polymerization product can go up to 30% by weight.

The polymerization conditions are known to those skilled in the art

and the temperature is generally between 0 and 100°C, preferably 40-90°C with olefih partial pressure equal to or greater than atmospheric pressure. The polymerization can be carried out in liquid phase with or without inert hydrocarbon as diluent, or in gas phase.

Favorable results are obtained by polymerization of propylene in the presence of inert aliphatic hydrocarbons at the polymerization conditions or by using liquid propylene as reaction medium.

The following examples shall illustrate the invention without limiting its scope.

The figures regarding specific surface are measured by absorption of liquid nitrogen (BET method).

The porosity (total porosity) is measured in a similar way by absorption of liquid nitrogen (pores with radius less than 500 Å).

Example 1

Preparation of the catalyst component.

2200 ml of dearomatized n-heptane and 800 g of TiCl4 were pickled in a 5 liter reactor. 1420 ml of heptane solution (500 g/l) Al2Et3Cl3 (molar ratio Al/Ti = 1.37) was then added. The addition of the aluminum compound was carried out dropwise while keeping the reaction mixture under stirring, during 90 minutes and at a temperature between 8 and 10°C.

The mixture was left under stirring at 8 - 10° C. for 4 hours. The reaction mixture was heated to 90° C. and held at this temperature for 90 minutes (temperature pretreatment).

The mixture was then cooled to room temperature and washed several times with n-heptane (5 times 2000 ml). The solid which had been reduced and temperature-pretreated (1000

g) was suspended in 2500 ml of n-heptane. To the suspension was added 600 g of di-n-butyl ether at room temperature (molar ratio ether/

Ten approximately equal to 1.1).

The temperature of the reaction mixture was increased to 90° C. and maintained at this temperature for 2 hours. After cooling to room temperature, the reaction mixture was washed several times with n-heptane and after drying under vacuum at 40° C, a

catalyst component with a brown color that showed an X-ray spectrum (CuK a) with the following characteristic lines:

d = 5.4 Å (solid line)

d = 2.75 Å (medium strong line)

d = 2.12 Å (medium strong line)

d = 1.98 Å (very weak line)

d = 1.77 Å (medium strong line).

This component is further characterized by:

The elemental analysis gave the following results:

Polymerization of propylene in n-heptane

An autoclave with a volume of 2.5 liters, made of stainless steel, was filled with 1000 ml of n-heptane, 0.15 g of solid catalyst component prepared as indicated above and 1.5 g of AlEt 2 Cl. The polymerization was carried out at 70° C. under a pressure of 5 ato with propylene and hydrogen (1.5 vol% in gas phase) for 4 hours.

The pressure was kept constant by constant introduction of propylene.

At the end of the reaction, the n-heptane was removed by stripping off with steam and a reaction product of polypropylene was obtained which showed an extraction residue after boiling in n-heptane equal to 97% and a yield of 114 g of polymer per g catalyst complex per hour per atmosphere propylene.

If one repeats the example but carries out the temperature pre-treatment at temperatures higher than 100° C, a catalyst component is obtained in which TiCl^ under X-ray diffraction shows a spectrum of the delta type. If the pre-treatment takes place by

130° C for 90 minutes and one operates with the ether treatment

with a reaction product that has a TiC^/ether ratio equal to 2:1, a catalyst component is obtained in which TiCl- is found in crystalline A-form with a surface area equal to 132 m/g and a porosity of 0.16 cm<3>/g .

The elemental analysis gave the following results:

This catalyst component used in polymerization. The extraction of propylene in n-heptane under conditions as described above gives polypropylene with an extraction residue of 94% and a yield of 65 g polymer/g catalyst component/hour/atm propylene.

If, on the other hand, the weight ratio reaction product/ether is equal to 4:1, a catalyst component similar to the previous one is obtained and when it is used in the polymerization of propylene under the described conditions, a polypropylene is obtained with an extraction residue equal to 90% in a yield of 46 .5 g of polymer per grams of catalyst component x hour x atm propylene.

From these comparison data, one can clearly see the improved properties of catalysts produced from catalyst components according to the invention, particularly with regard to the yield achieved.

Example 2.

Example 1 is repeated but without temperature pretreatment at 90° C for 90 minutes... A solid catalyst component characterized by the following properties is obtained:

The elemental analysis showed the following results:

This catalyst complex was used for the polymerization of propylene in n-heptane under the reaction conditions as stated in example 1, and polypropylene is obtained with an extraction residue in boiling n-heptane equal to 95.5% and a yield of 98.8 g polymer/g catalyst component /hour/atmosphere propylene.

Example 3

Example 1 is repeated but AlEt2Cl is used as reducing agent instead of A^Et^C^. The reduction was carried out with a molar ratio Al/Ti = 1.1:1.

The aluminum compound was added dropwise and the reaction mixture stirred for approx. 90 minutes at 0° C..

The reaction mixture was left with stirring at 0° C. for 4 hours, after which the mixture was heated to 60° C. and held at this temperature for 90 minutes.

By proceeding as described in example 1, a crystalline substance was obtained which showed the following properties:

The elemental analysis showed the following results:

This catalyst component used in the polymerization of propylene in n-heptane under the same conditions as in example 1 gave a polypropylene with an extraction residue in boiling n-heptane equal to 92.5% and yield equal to 89 g polymer/g catalyst component per hour per ata of propylene.

Example 4

Example 1 was repeated but AlEtCl2 was used. reducing agent for TiCl^, with a molar ratio Al/Ti equal to 1.5:1. The addition of aluminum compound was done dropwise. with the reaction mixture being stirred for 90 minutes at a temperature of 20°. C- The mixture was then stirred for 4 hours at 20°C.

Without heat treatment, the reaction product after washing was treated with ether as described in example 1. A catalyst component with the following properties was obtained:

X-ray spectrum: the same line was obtained as in example 1

The elemental analysis gave the following results:

This catalyst component used in the polymerization of propylene in n-heptane under conditions as stated in example 1 gave a polypropylene with an extraction residue in boiling n-heptane equal to 95.5% with a yield of 90 g of polymer per g

catalyst component per hour per ata propylene.

Example 5

Example 1 was repeated but the treatment with ether was carried out at 70° C. for 2 hours. A catalyst component was thereby obtained which showed the following characteristics: X-ray spectrum: one got the same lines as the component i

example 1,

The elemental analysis showed the following results:

This catalyst component used in the polymerization of propylene in n-heptane as described in example 1 gave a polypropylene with an extraction residue in boiling n-heptane equal to 91.5% and a yield of 96 g of polymer per g catalyst component per hour per ata propylene..

Example 6

Example 1 was repeated and the treatment with ether was carried out at 120° C. for 2 hours. A catalyst component was obtained which had the following properties: X-ray spectrum: the same lines as the component were obtained

according to example 1,

The elemental analysis gave the following results:

This catalyst component used in the polymerization of propylene in boiling n-heptane under the conditions described in example 1 gave polypropylene with an extraction residue in boiling n-heptane equal to 90% and a yield of 90 g of polymer per g catalyst component per hour per atm. propylene.

Example 7

Example 1 was repeated but the polymerization was carried out with propylene in n-heptane under the following conditions after heat treatment:

After prepolymerization, the catalyst component was treated with ether as described in Example 1, the properties of the catalyst component were as follows:

The elemental analysis showed the following results:

Catalyst components used in the polymerization of propylene under conditions as in example 1 gave a polypropylene with an extraction residue in boiling heptane equal to 96% and a yield of 55 g of polypropylene per g catalyst component per hour per atm. propylene.

If one takes into account that the catalyst component contains 50% polypropylene, the yield with respect to TiCl^ was equal to 110 g polypropylene per g catalyst component (TiC^) per hour currently atm. propylene.

Claims (17)

1. Catalyst components for the polymerization of olefins, containing TiCl-j, characterized in that the X-ray spectrum of the components shows lines with the following lattice spacings: d = 5.4 Å (strong line), d = 2.75 Å (medium strong line), d = 2 .12 Å (medium weak line), d = 1.98 Å (very weak line), d 1.77 Å (medium strong line). 2. Catalytic converter components. as stated in example 1, characterized in that they consist of or contain products with the following composition: where R is a hydrocarbon residue with 1-20 and preferably 2-10 carbon atoms, and in particular alkyl, aryl, cycloalkyl, alkylaryl or aralkyl, m greater than or equal to 0, less than or equal to 2.5, X denotes halogen, a denotes a number below 0.4 and preferably below 0.2, A denotes 1 mole of monoether or polyether which with aluminum or alkyl aluminum halides can form complexes or coordination compounds which are soluble in at least one solvent chosen from the monoether or polyether itself, aromatic or aliphatic hydrocarbons and their halogen derivatives, p is a number equal to or greater than zero and less than 0.5, generally between 0.001 and 0.5. 3. Catalyst component specified in claims 1 and 2, characterized by a surface area of between 1 and 50 m/g, more particularly between 2 and .20 m^/g, porosity below 0.1 cm <3>/g, especially between 0 .05 and 0.001 cm <3> /g. 4. Catalyst components specified in claim 2, characterized in that said monoethers are chosen from those with the general formula R'OR" where R <1> and R", the same or different, denote alkyl groups with 1 - 10, preferably 4 - 6 carbon atoms, aryl groups , cycloalkyl groups, alkylaryl groups or aralkyl groups. 5. Catalyst components as specified in claim 1, characterized in that said monoether is selected from among di-n-butyl ether, di-iso-amyl ether <p> and the like. 6. Catalyst components as specified in claim 2, characterized in that the polyethers are selected from among diethylene glycol dimethyl ether > 1,2-diphenoxyethane and the like. 7. Catalyst components for polymerization of olefins as described in the description and examples. 8. Catalysts for the polymerization of olefins produced by bringing aluminium-organometallic compounds into contact with catalyst components as stated in claims 1 - 7. 9. Catalysts for the stereospecific polymerization of ,CH 2 CHR <x-> a-olefins (where RX denotes alkyl with 1-4 carbon atoms), prepared by bringing dialkyl aluminum halides and aluminum sesquihalides into contact with catalyst components as stated in claims 1-7. 10. Method for the production of catalyst components as specified in claims 1-7, characterized in that the following steps are carried out in the specified order: 1st stage reduction of TiCl^ with aluminium-organometallic compounds of formula AIRX2, A1R2X or A <I> 2R3<X>2 , where R and X have the previously stated meanings, 2..step - possibly but not necessarily, thermally forbe action of the reduction product at 20 - 100° C during treatment times which depend on the temperature and are generally from 10 minutes to 5 hours, 3rd step - treatment of the reduction product, possibly pre-treated with heat according to step 2, with a mono- or polyether as defined above by a temperature between 70 and 120° C and finally . 4th step - washing the manufactured product from the 3rd step . with an inert hydrocarbon. 11. Procedure as stated in claim 10, character- t i s e t by using as a reducing agent an alkyl aluminum halide selected from among -dichlorides, -monochlorides and ethyl or propyl aluminum sesquichloride. 12. Method as stated in claim 10, characterized in that in the 1st step the Al/Ti ratio is kept at 0.1-5, preferably 0.5-2. 13. Method as stated in claim 10, characterized in that in the 2nd step a temperature is maintained between 60 and 90° C. 14. Method as stated in claim 10, character, e-r i s e r t in that in the 3rd step the molar ratio ether/Ti = 0.5 - 2.5, preferably 0.8 - 1.5. 15. Method for the production of solid catalyst components as stated in claims 1 - 7, according to the description and examples. 16. Process for the polymerization of olefins, characterized by using the catalyst as specified in claim 8. 17. Process for the production of crystalline polymers and copolymers of CH2=CHR X -a-olefins (R x denotes alkyl with 1-4 carbon atoms), characterized in that the CH2=CH1 -a-olefins or mixtures with each other and/or with ethylene is polymerized using catalysts as specified in claim 9.