CN108203476A - A kind of supported polyethylene catalyst and preparation method thereof - Google Patents

Abstract

The invention relates to a supported polyethylene catalyst, comprising a porous inorganic carrier and an active component, the active component being an organic chromium source, an inorganic chromium source and an organic molybdenum source; the total loading of Cr and Mo in the active component The amount is 0.01wt%～20wt% of the total weight of the catalyst; the molar ratio of Cr and Mo is 0.01:0.99～0.99:0.01; the molar ratio of Cr in the organic chromium source and the inorganic chromium source is 1:9 ~9:1. The invention also relates to a preparation method of the supported polyethylene catalyst. In the catalyst of the present invention, the active site of Mo can increase the loading amount of the organic chromium source of the catalyst, improve the content of polyethylene polymerized monomers and the distribution uniformity of comonomers.

Description

A kind of supported polyethylene catalyst and preparation method thereof

technical field

The invention relates to a supported polyethylene catalyst and a preparation method thereof, in particular to a supported polyethylene catalyst containing chromium and molybdenum and a preparation method thereof.

Background technique

As an important species of ethylene polymerization catalysts, chromium-based catalysts were first used in the production of polyethylene. Since the initial success of the research on silica gel (SiO ₂ ) or silica gel-alumina (SiO ₂ -Al ₂ O ₃ ) supported chromium oxide catalysts, it has been found that the preparation method of silica gel and the activation method after loading chromium-based catalysts can be Change the relative molecular mass of the product (hereinafter referred to as molecular weight). Supported chromium-based catalysts have been widely used in solution, slurry, and gas phase PE production processes. Hogan and Banks of Phillips discovered the CrO ₃ /SiO ₂ catalyst for ethylene polymerization in 1951, and Unide-Carbide developed the most famous Cp ₂ Cr catalyst on the basis of Phillips, thus pioneering the use of chromium-based catalysts as ethylene A very important field of polymerization catalysts.

USP2825721 is the first invention patent of chromium-based polyethylene catalyst obtained by Phillips Petroleum Company in 1958. This patent first reported that chromium oxide has high ethylene polymerization activity after being supported on the surface of silica gel or alumina carrier. This patent was later adopted by Phillips Petroleum companies realize the industrialized production of high-density polyethylene, which is used in the slurry-loop polyethylene process, and the chromium loading of the catalyst is 1% (percentage by weight). After more than 50 years of development, a series of modifications and improvements have been carried out. Up to now, there have been more than 600 patents (Phillips Petroleum Company has more than 300 patents), among which the most widely used patented technologies are titanium modification and aluminum alloy. Modified Phillips chromium catalyst patented technology.

USP4049896 introduced a patented technology of aluminum-modified Phillips chromium-based catalysts, which was first reported by USI/Equistar in 1977, mainly through the introduction of metal aluminum salts in the catalyst preparation process (finally converted to alumina during the firing process) The modification of Phillips chromium-based catalysts, aluminum modification can improve the polymerization activity of the catalyst, reduce the molecular weight of the polymer to enhance the molecular weight control means, broaden the molecular weight distribution to improve the processing performance and product properties, and enhance the stress cracking resistance of the polymer. Related improvement patents have USP4052544 etc.

USP3780011 introduced a patented technology of titanium-modified Phillips chromium series catalysts, which was first reported by Chemplex/Equistar in 1971, mainly through the introduction of metal titanium salts in the catalyst preparation process (finally converted to oxidized Titanium) to modify the Phillips chromium catalyst, titanium modification can improve the polymerization activity of the catalyst, reduce the molecular weight of the polymer to enhance the means of molecular weight regulation, broaden the molecular weight distribution to improve the processing performance and product properties, and enhance the stress cracking resistance of the polymer. Strength and extrusion expansion etc. Related improvement patents have USP4053436 etc.

EP563274 introduces a fluorine-modified chromium-based catalyst technology. Inorganic fluorine is added to the chromium oxide catalyst before activation. Adding inorganic fluorine (such as HF, (NH ₄ ) ₂ SiF ₆ , (NH ₄ ) ₃ BF _{6 ,} etc.) can change the hydrogen tuning sensitivity of the chromium oxide catalyst and obtain HDPE products with narrow molecular weight distribution. Further improving the titanium-impregnated chromium oxide catalyst with fluorine can increase the comonomer addition rate and improve the copolymerization performance of the polymer, and with the increase of the fluorine content, the low molecular weight part and melt index of the copolymer decrease. The promotion effect of fluorine on chromium catalyst is because fluorine reacts with surface silanol groups to release water and form surface Si—F bond. It can be seen from the low-temperature infrared spectrum of CO that fluorine treatment reduces the electron cloud density of chromium atoms and changes the distribution of active sites, thereby improving the physical properties of PE products.

USP5032651 introduced a method to compound a zirconium metallocene catalyst and a chromium-containing catalyst to form a polyethylene resin with high hardness and good environmental stress crack resistance, which is especially suitable for the production of film grade products.

CN1350007A introduces a nickel-modified ethylene polymerization chromium catalyst and its preparation method. The catalyst prepared by the method has high polymerization activity and good copolymerization performance, and the produced polymer has relatively high molecular weight.

CN1296020A has introduced a titanium, nickel modified ethylene polymerization chromium series catalyst and its preparation method. The catalyst prepared by this method has high polymerization activity and good copolymerization performance, and the produced polymer has a higher melt flow rate And wider molecular weight distribution, said chromium, nickel, titanium all exist in oxide form after activation.

CN1858072 introduced a titanium-modified carrier-type chromium-based catalyst and its preparation method. The carrier of the catalyst is silica gel. Titanium compounds and chromium compounds are loaded on the silica gel carrier. The prepared catalyst has strong hydrogen tuning ability and can be used It is suitable for the production of high melt index polymers, low polymer shear response (HLMI/MI ratio), and is suitable for the production of ethylene homopolymers and copolymers with a wide molecular weight distribution for the manufacture of films and pipes.

The invention is a supported polyethylene catalyst containing two chromium sources and one organic molybdenum source. The method can improve the copolymerization performance of the catalyst, and there is no relevant report about using the method so far.

Contents of the invention

The object of the present invention is to provide a supported polyethylene catalyst and its preparation method. The catalyst prepared by the present invention has the characteristics of high active center loading and good catalyst copolymerization performance.

To achieve the above object, the present invention provides a supported polyethylene catalyst, comprising a porous inorganic carrier and an active component, the active component being an organic chromium source, an inorganic chromium source and an organic molybdenum source; in the active component, Cr , The total loading of Mo is 0.01wt%～20wt% of the total weight of the catalyst, preferably 0.05wt%～15wt%, more preferably 0.1wt%～10wt%; the molar ratio of Cr and Mo is 0.01:0.99～0.99: 0.01, preferably 0.25:0.75～0.75:0.25, more preferably 0.4:0.6～0.6:0.4; the molar ratio of Cr in the organic chromium source to the inorganic chromium source is 1:9～9:1, preferably 2:8 ~8:2, more preferably 3:6~6:3.

The supported polyethylene catalyst of the present invention, wherein the inorganic chromium source is preferably chromium trioxide, chromium nitrate, chromium acetate, chromium chloride, chromium sulfate, ammonium chromate, ammonium dichromate and basic chromium acetate at least one of the

In the supported polyethylene catalyst of the present invention, the organic chromium source is preferably at least one selected from bis-triphenylsilyl chromate, chromocene and organosilane chromate.

The supported polyethylene catalyst of the present invention, wherein the organic molybdenum source is preferably oxymolybdenum dialkyldithiophosphate, nitrogen-containing molybdenum dialkyldithiophosphate, dialkyldithiocarbamic acid At least one of molybdenum, molybdenum amine complex, molybdenum naphthenate and molybdenum alkyl salicylate.

In the supported polyethylene catalyst of the present invention, the organic chromium source is preferably organic chromium treated with an organoaluminum compound.

In the supported polyethylene catalyst of the present invention, the organic molybdenum source is preferably organic molybdenum treated with an organoaluminum compound.

The supported polyethylene catalyst of the present invention, wherein, preferably, the organoaluminum compound is an alkylaluminum compound, and conforms to the general formula R ₁ -Al-OR ₂ , where R ₁ and R ₂ are the same or are different, and each independently represents a C1-12 alkyl group. More preferred organoaluminum compounds are triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, triisopropylaluminum, methyldiethylaluminum, trimethylaluminum, diethylaluminum ethoxide (DEAlE), One of diethylaluminum methoxide, dimethylaluminum ethoxide, diisopropylaluminum ethoxide, diethylaluminum propoxide, diisobutylaluminum ethoxide and methylethylaluminum ethoxide.

In the supported polyethylene catalyst of the present invention, preferably, the porous inorganic carrier is obtained by modifying the inorganic carrier.

The supported polyethylene catalyst of the present invention, wherein, the inorganic carrier is preferably at least one selected from silica, aluminum oxide, titanium dioxide, zirconium oxide, magnesium oxide, calcium oxide, inorganic clay and montmorillonite kind.

The supported polyethylene catalyst of the present invention, wherein the average particle diameter of the inorganic support is preferably 1 micron to 100 microns, more preferably 20 microns to 80 microns; the pore volume is preferably 0.5 cm ³ /g to 10.0 cm ³ /g, more preferably 2 cm ³ /g to 8.0 cm ³ /g; the surface area is preferably 50 m ² /g to 1000 m ² /g, more preferably 200 m ² /g to 700 m ² /g.

The supported polyethylene catalyst according to the present invention, wherein the modification is preferably aluminum modification: the inorganic support is impregnated with an aluminum salt solution, and the aluminum salt is selected from Al(NO ₃ ) ₃ , AlCl ₃ and Al ₂ (SO ₄ ) ₃ in one.

In the supported polyethylene catalyst of the present invention, the modification is preferably titanium modification, which is modified by impregnation method or Cogel method.

In the supported polyethylene catalyst of the present invention, the modification is preferably fluorine modification: the inorganic carrier is co-impregnated with the fluorine-containing component.

The present invention also provides a kind of preparation method of supported polyethylene catalyst, it is the preparation method of above-mentioned supported polyethylene catalyst, comprises the following steps:

(1) Immerse the porous inorganic carrier in an aqueous solution containing inorganic chromium salts, the immersion time is 1-12h, the immersion temperature is 25-100°C, and then dried at 100-300°C for 5-20h, in 300°C-1000°C air Roasting in the air for 1-12h;

(2) Immerse the product obtained in step (1) into the organic solution of organic chromium source and organic molybdenum source, the immersion time is 1-12h, the immersion temperature is 25-100°C, and then in a nitrogen atmosphere between 100-300°C Dry for 5-20 hours to finally obtain a supported polyethylene catalyst.

In the method for preparing a supported polyethylene catalyst of the present invention, in step (2), the organic solvent in the organic solution is preferably ethanol, propanol, butanol, octanol, ethylene glycol, propylene glycol, butanediol, Octanediol, pentane, hexane, heptane, octane, benzene, toluene, xylene or isomers of the above substances.

The specific steps of porous inorganic carrier modification of the present invention are:

The Al modification can be prepared by a gel method to prepare an Al ₂ O ₃ modified inorganic carrier, and the Al ₂ O ₃ modification that can also be achieved by impregnating the inorganic carrier with an aluminum salt solution, the aluminum salt solution is selected from Al(NO ₃ ) ₃ , AlCl ₃ and Al ₂ (SO ₄ ) ₄ at least one. The suitable conditions for the process of modifying the inorganic carrier are: make the aluminum salt into an aqueous solution with a concentration of 10wt% to 25wt%, add dilute acid to adjust the pH to 1 to 1.8, raise the temperature to 40°C to 60°C, add SiO ₂ , and stir vigorously Immerse under water for 12h to 24h, then rinse with distilled water until the pH is 7, then dry and roast to obtain an Al ₂ O ₃ modified porous inorganic carrier;

The titanium-modified porous inorganic support can be prepared by an impregnation method or a Cogel method. Impregnation method, that is, the inorganic carrier is immersed in the organic solution of titanate or TiC1 ₄ , and the titanate or TiC1 ₄ chemically reacts with the hydroxyl groups on the surface of the carrier to load titanium on the surface of the carrier, and then prepare titanium modified sex carrier. Usually hydrocarbons are used as organic solvents, such as hexane or heptane. The Cogel method is to dissolve soluble titanium salt in silicate, such as sodium silicate, and increase the pH value of the solution to form a co-gel of carrier and _TiO2 , or dissolve silicon ester and titanium ester in alcohol or acetone , add a small amount of water to prepare carrier and TiO co _- gel;

The fluorine-modified porous inorganic carrier, the introduction of the fluorine component can be prepared by impregnating the inorganic carrier into the (NH ₄ ) ₂ SiF ₆ solution, and the (NH ₄ ) ₂ SiF ₆ concentration is 1% to 10% mole fraction.

The supported polyethylene catalyst of the present invention is used to produce ethylene homopolymer and ethylene and α-olefin copolymer, and the α-olefin is 1-propylene, 1-butene, 1-pentene, 1-hexene Any one or more of ene, 1-octene and 1-decene.

The beneficial effects of the present invention are: the supported polyethylene catalyst of the present invention contains the Cr active sites of the organic chromium source and the inorganic chromium source and the Mo active site of the organic molybdenum source on the same porous inorganic carrier; Active metal loading increases polyethylene polymerized monomer content and comonomer distribution uniformity.

Detailed ways

The following examples are provided to further illustrate the method of the present invention, but should not be limited thereto.

The evaluation method of the catalyst in the present invention is as follows: 200 mg of the composite catalyst is weighed to carry out the polymerization experiment. The polymerization reactor was heated in vacuum (100°C) in advance, and then replaced with high-purity nitrogen. The operation was repeated three times, and then replaced once with a small amount of monomer ethylene. Finally, the reactor was filled with ethylene to a slight positive pressure (0.15MPa). The polymerization temperature was controlled at 90°C. Add about 150mL of refined heptane after dehydration and deoxygenation to the reaction kettle in turn as a solvent, add an organoaluminum compound as a cocatalyst, the cocatalyst concentration is 1.82mmol/mL (n-hexane solution), and the dosage is 0.30mL, and finally add the composite catalyst Polymerization begins. During the reaction process, the instantaneous consumption of monomer ethylene was collected online (through a high-precision ethylene mass flow meter connected to a computer) and recorded by the computer. After the reaction was carried out at 90° C. for 1 hour, a mixed solution of hydrochloric acid/ethanol was added to terminate the reaction, and the polymer was dried in vacuum and then weighed and analyzed for product properties.

Example 1:

The inorganic carrier silica has an average particle size of 58 microns, a pore volume of 4.7 cm ³ /g, and a surface area of 255 m ² /g. The porous inorganic carrier is obtained by preparing Al ₂ O ₃ by gel method. Immerse the modified silicon dioxide in the aqueous solution of chromium oxide for 8 hours and immersion temperature at 65°C, then dry it at 150°C for 10 hours, and bake it in the air atmosphere at 550°C for 8 hours; In the ethylene glycol solution of chromocene and dialkylmolybdenum dithiophosphate, the immersion time is 7h, the immersion temperature is 55°C, and then dried in nitrogen atmosphere at 200°C for 5-20h. The total loading of Cr and Mo metals on the porous inorganic support is 8.5wt% of the total weight of the catalyst, the molar ratio of Cr and Mo is 0.88:0.12, and the molar ratio of Cr in the inorganic chromium source and the organic chromium source is 8:2 .

Catalyst evaluation method is adopted to analyze catalyst, wherein, cocatalyst is triisobutylaluminum, polymerization monomer 1-butene, and the polyethylene product performance of preparation is as follows: melt flow rate is 4.7g/10min (5Kg weight), density It is 0.9480g/10min.

Example 2:

The inorganic carrier magnesium oxide has an average particle diameter of 15 microns, a pore volume of 9.1 cm ³ /g, and a surface area of 270 m ² /g. The porous inorganic carrier is obtained through titanium modification. The porous inorganic carrier is immersed in the aqueous solution of chromium sulfate, the immersion time is 6h, the immersion temperature is 45°C, then dried at 180°C for 15h, and calcined in the air atmosphere of 450°C for 4h; In octane glycol solution of molybdenum dithiocarbamate, the immersion time is 4h, the immersion temperature is 80°C, and then dried in nitrogen atmosphere at 190°C for 18h. The total loading of Cr and Mo metals on the porous inorganic support is measured to be 4.2wt% of the total weight of the catalyst, the molar ratio of Cr and Mo is 0.42:0.58, and the molar ratio of Cr in the inorganic chromium source and the organic chromium source is 4:6 .

Adopt catalyst evaluation mode to analyze catalyst, wherein, cocatalyst is triisopropyl aluminum, polymerization monomer 1-pentene, the performance of the polyethylene product of preparation is as follows: melt flow rate is 1.2g/10min (5Kg weight), density It is 0.9487g/10min.

Example 3:

The inorganic carrier titanium dioxide has an average particle diameter of 2 microns, a pore volume of 7.7 cm ³ /g, and a surface area of 350 m ² /g, and is modified by aluminum to obtain a porous inorganic carrier. Immerse the porous inorganic carrier in the aqueous solution of ammonium dichromate, the immersion time is 4h, the immersion temperature is 70°C, then dry at 240°C for 9h, and bake in the air atmosphere at 600°C for 12h; In the heptane solution of acid ester and molybdenum amine complex, the immersion time is 7h, the immersion temperature is 70°C, and then dried in nitrogen atmosphere at 230°C for 20h. The total loading capacity of Cr and Mo metals measured on the porous inorganic carrier is 3.8wt% of the total weight of the catalyst, the molar ratio of Cr and Mo is 0.23:0.77, and the molar ratio of Cr in the inorganic chromium source and the organic chromium source is 2:8 .

Catalyst evaluation mode is adopted to analyze catalyst, wherein, cocatalyst is triisopropylaluminum, polymerization monomer 1-hexene, the polyethylene product performance of preparation is as follows: melt flow rate is 3.5g/10min (5Kg weight), density It is 0.9459g/10min.

Example 4:

The inorganic carrier montmorillonite has an average particle size of 77 microns, a pore volume of 4.9 cm ³ /g, and a surface area of 600 m ² /g, and is modified by fluorine to obtain a porous inorganic carrier. Immerse the porous inorganic carrier in the aqueous solution of chromium trioxide, the immersion time is 10h, the immersion temperature is 55°C, then dry at 160°C for 13h, and roast in the air atmosphere at 350°C for 1h; In the toluene solution of silyl chromate and nitrogen-containing molybdenum dialkyldithiophosphate oxymolybdenum, the immersion time is 3h, the immersion temperature is 55°C, and then dried in nitrogen atmosphere at 170°C for 14h. The total loading of Cr and Mo metals on the porous inorganic support is 0.1wt% of the total weight of the catalyst, the molar ratio of Cr and Mo is 0.35:0.65, and the molar ratio of Cr in the inorganic chromium source and the organic chromium source is 8:2 .

Adopt catalyst evaluation mode to analyze catalyst, wherein, cocatalyst is triisopropyl aluminum, polymerization monomer 1-decene, the polyethylene product performance of preparation is as follows: melt flow rate is 9.2g/10min (5Kg weight), density It is 0.9481g/10min.

Example 5:

The inorganic carrier calcium oxide has an average particle diameter of 41 microns, a pore volume of 1.3 cm ³ /g, and a surface area of 240 m ² /g. The porous inorganic carrier is obtained through fluorine modification. Immerse the porous inorganic carrier in the aqueous solution of chromium chloride, the immersion time is 1h, the immersion temperature is 90°C, then dry at 200°C for 18h, and bake in the air atmosphere at 450°C for 8h; Esters and molybdenum dialkyldithiocarbamate in octanol solution, the immersion time is 12h, the immersion temperature is 35℃, and then dried in nitrogen atmosphere at 270℃ for 17h. The total loading of Cr and Mo metals on the inorganic carrier was measured to be 20wt% of the total weight of the catalyst, the molar ratio of Cr and Mo was 0.29:0.71, and the molar ratio of Cr in the inorganic chromium source and the organic chromium source was 7:3.

Adopt catalyst evaluation mode to analyze catalyst, wherein, cocatalyst is triisopropyl aluminum, polymerization monomer 1-butene, the polyethylene product performance of preparation is as follows: melt flow rate is 8.7g/10min (5Kg weight), density It is 0.9421g/10min.

Embodiment 6:

Inorganic carrier Inorganic clay, with an average particle size of 99 microns, a pore volume of 6.5 cm ³ /g, and a surface area of 100 m ² /g, which is porous through aluminum modification. Immerse the porous inorganic carrier in the aqueous solution of ammonium chromate, the immersion time is 3h, the immersion temperature is 35°C, then dry at 120°C for 7h, and bake in the air atmosphere at 550°C for 6h; In the propanol solution of molybdenum naphthenate, the immersion time is 6h, the immersion temperature is 50°C, and then dried in nitrogen atmosphere at 150°C for 12h. The total loading of Cr and Mo metals on the inorganic carrier was measured to be 13.1wt% of the total weight of the catalyst, the molar ratio of Cr and Mo was 0.51:0.49, and the molar ratio of Cr in the inorganic chromium source and the organic chromium source was 1:9.

Catalyst evaluation mode is adopted to analyze catalyst, wherein, cocatalyst is triisopropylaluminum, polymerization monomer 1-butene, the polyethylene product performance of preparation is as follows: melt flow rate is 5.2g/10min (5Kg weight), density It is 0.9512g/10min.

Embodiment 7:

The inorganic carrier zirconia has an average particle diameter of 83 microns, a pore volume of 5.1 cm ³ /g, and a surface area of 180 m ² /g, and is modified by aluminum to obtain a porous inorganic carrier. The porous inorganic carrier is immersed in the aqueous solution of basic chromium acetate, the immersion time is 2h, the immersion temperature is 100°C, then dried at 220°C for 16h, and roasted in the air atmosphere of 400°C for 10h; In the hexane solution of phenylsilyl chromate and molybdenum oxymolybdenum dithiophosphate containing nitrogen, the immersion time is 4h, the immersion temperature is 65°C, and then dried in nitrogen atmosphere at 210°C for 2h. The total loading of Cr and Mo metals on the porous inorganic support is 1.9wt% of the total weight of the catalyst, the molar ratio of Cr and Mo is 0.15:0.85, and the molar ratio of Cr in the inorganic chromium source and the organic chromium source is 5:5 .

Adopt catalyst evaluation mode to analyze catalyzer, wherein, cocatalyst is triisopropylaluminum, polymerization monomer 1-pentene, the polyethylene product performance of preparation is as follows: melt flow rate is 3.8g/10min (5Kg weight), density It is 0.9452g/10min.

Embodiment 8:

The inorganic carrier aluminum oxide has an average particle size of 60 microns, a pore volume of 3.7 cm ³ /g, and a surface area of 1000 m ² /g. The porous inorganic carrier is obtained through titanium modification. The porous inorganic carrier is immersed in the aqueous solution of chromium nitrate, the immersion time is 12h, the immersion temperature is 25°C, then dried at 100°C for 5h, and calcined in 800°C air atmosphere for 4h; the obtained product is immersed in a bis-triphenyl In the octane solution of silyl chromate and molybdenum alkyl salicylate, the immersion time is 2h, the immersion temperature is 80°C, and then dried at 100°C in nitrogen atmosphere for 11h. The total loading of Cr and Mo metals on the porous inorganic carrier measured by ICP is 4.1wt% of the total weight of the catalyst, the molar ratio of Cr and Mo is 0.41:0.59, and the molar ratio of Cr in the inorganic chromium source and the organic chromium source is 6 :4.

Adopt catalyst evaluation mode to analyze catalyst, wherein, cocatalyst is triisopropyl aluminum, polymerization monomer 1-propylene, the polyethylene product performance of preparation is as follows: melt flow rate is 2.7g/10min (5Kg weight), and density is 0.9439g/10min.

Embodiment 9:

The inorganic carrier magnesium oxide has an average particle diameter of 35 microns, a pore volume of 0.5 cm ³ /g, and a surface area of 50 m ² /g. The porous inorganic carrier is obtained through titanium modification. Immerse the porous inorganic carrier in the aqueous solution of chromium acetate, the immersion time is 11h, the immersion temperature is 45°C, then dry at 300°C for 2h, and bake in the air atmosphere at 1000°C for 3h; In the octane solution of alkylmolybdenum dithiophosphate, the immersion time is 1h, the immersion temperature is 30°C, and then dried in nitrogen atmosphere at 300°C for 1h. The total loading of Cr and Mo metals on the porous inorganic carrier is measured to be 17.3wt% of the total weight of the catalyst, the molar ratio of Cr and Mo is 0.68:0.32, and the molar ratio of Cr in the inorganic chromium source and the organic chromium source is 3:7 .

Catalyst evaluation method is adopted to analyze catalyst, wherein, cocatalyst is triisopropylaluminum, polymerization monomer 1-butene, and the polyethylene product performance of preparation is as follows: melt flow rate is 0.9g/10min (5Kg weight), density It is 0.9508g/10min.

Example 10:

The inorganic carrier calcium oxide has an average particle diameter of 55 microns, a pore volume of 10.0 cm ³ /g, and a surface area of 680 m ² /g. The porous inorganic carrier is obtained through titanium modification. The porous inorganic carrier is immersed in the aqueous solution of chromium sulfate, the immersion time is 7h, the immersion temperature is 80°C, then dried at 260°C for 11h, and roasted in the air atmosphere of 300°C for 9h; In the benzene solution of molybdenum alkanoate, the immersion time is 5h, the immersion temperature is 40°C, and then dried in nitrogen atmosphere at 190°C for 13h. The total loading of Cr and Mo metals on the porous inorganic support is 12.4wt% of the total weight of the catalyst, the molar ratio of Cr and Mo is 0.19:0.81, and the molar ratio of Cr in the inorganic chromium source and the organic chromium source is 4:6 .

Adopt catalyst evaluation mode to analyze catalyzer, wherein, co-catalyst is triisopropyl aluminum, polymerization monomer 1-hexene, the polyethylene product performance of preparation is as follows: melt flow rate is 7.7g/10min (5Kg weight), density It is 0.9438g/10min.

Comparative Example 1:

Inorganic carrier silica, with an average particle size of 58 microns, a pore volume of 4.7 cm ³ /g, and a surface area of 255 m ² /g, was modified by preparing Al ₂ O ₃ by a gel method. The modified silicon dioxide was immersed in the aqueous solution of chromium oxide for 8 hours, the immersion temperature was 65°C, then dried at 150°C for 10 hours, and calcined in the air atmosphere of 550°C for 8 hours; the modified inorganic The total loading of Cr metal on the support is 8.5wt% of the total weight of the catalyst.

Catalyst evaluation method is adopted to analyze catalyst, wherein, cocatalyst is triisobutylaluminum, polymerization monomer 1-butene, and the polyethylene product performance of preparation is as follows: melt flow rate is 4.9g/10min (5Kg weight), density It is 0.9502g/10min.

Example 2:

The inorganic carrier magnesium oxide has an average particle diameter of 15 microns, a pore volume of 9.1 cm ³ /g, and a surface area of 270 m ² /g. The porous inorganic carrier is obtained through titanium modification. The porous inorganic carrier was immersed in an aqueous solution of chromium sulfate for 6 hours at 45°C, then dried at 180°C for 15 hours, and calcined at 450°C for 4 hours in an air atmosphere. The loading amount of Cr metal on the porous inorganic carrier was measured to be 4.2 wt% of the total weight of the catalyst.

Catalyst evaluation method is adopted to analyze catalyst, wherein, co-catalyst is triisopropyl aluminum, polymerization monomer 1-pentene, and the polyethylene product performance of preparation is as follows: melt flow rate is 1.0g/10min (5Kg weight), density It is 0.9513g/10min.

Example 3:

The inorganic carrier titanium dioxide has an average particle diameter of 2 microns, a pore volume of 7.7 cm ³ /g, and a surface area of 350 m ² /g, and is modified by aluminum to obtain a porous inorganic carrier. The porous inorganic support was immersed in an aqueous solution of ammonium dichromate for 4 hours at a temperature of 70°C, then dried at 240°C for 9 hours, and calcined at 600°C for 12 hours in an air atmosphere. The total loading of Cr on the porous inorganic support was measured to be 3.8 wt% of the total weight of the catalyst.

Catalyst evaluation mode is adopted to analyze catalyst, wherein, cocatalyst is triisopropylaluminum, polymerization monomer 1-hexene, the polyethylene product performance of preparation is as follows: melt flow rate is 3.5g/10min (5Kg weight), density It is 0.9472g/10min.

It can be seen from the above examples and comparative examples that under the same active center loading, the polyethylene product prepared by the catalyst developed by the present invention has a lower density, indicating that the content of polymerized monomers is higher and the copolymerization performance of the catalyst is better.

Certainly, the present invention also can have other various embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes And deformation should belong to the protection scope of the present invention.

Claims (15)

1. a supported polyethylene catalyst is characterized in that, comprises porous inorganic carrier and active component, and described active component is organic chromium source, inorganic chromium source and organic molybdenum source; Cr, Mo in described active component The total load of the catalyst is 0.01wt%～20wt% of the total weight of the catalyst; the molar ratio of Cr and Mo is 0.01:0.99～0.99:0.01; the molar ratio of Cr in the described organic chromium source and the described inorganic chromium source is 1:9～9:1. 2. supported polyethylene catalyst according to claim 1, is characterized in that, described inorganic chromium source is chromium trioxide, chromium nitrate, chromium acetate, chromium chloride, chromium sulfate, ammonium chromate, ammonium dichromate and at least one of basic chromium acetate. 3. The supported polyethylene catalyst according to claim 1, characterized in that, the organic chromium source is selected from at least one of bis-triphenylsilyl chromate, chromocene and organosilane chromate A sort of. 4. The supported polyethylene catalyst according to claim 1, wherein the organic molybdenum source is oxymolybdenum dithiophosphate, nitrogen-containing dialkylmolybdenum dithiophosphate, dialkyl At least one of molybdenum dithiocarbamate, molybdenum amine complex, molybdenum naphthenate and molybdenum alkyl salicylate. 5. The supported polyethylene catalyst according to claim 1, characterized in that the organic chromium source is organic chromium treated with an organoaluminum compound. 6. The supported polyethylene catalyst according to claim 1, characterized in that the organic molybdenum source is organic molybdenum treated with an organoaluminum compound. 7. The supported polyethylene catalyst according to claim 5 or 6, characterized in that, the organoaluminum compound is an alkylaluminum compound, and conforms to the general formula R ₁ -Al-OR ₂ , wherein, R ₁ and R ₂ are the same or different, and are independently C1-12 alkyl groups. 8. The supported polyethylene catalyst according to claim 1, characterized in that the porous inorganic carrier is obtained by modifying the inorganic carrier. 9. The supported polyethylene catalyst according to claim 8, wherein the inorganic carrier is selected from the group consisting of silicon dioxide, aluminum oxide, titanium dioxide, zirconium oxide, magnesium oxide, calcium oxide, inorganic clay and montmorillonite At least one of the soil. 10. The supported polyethylene catalyst according to claim 8, characterized in that the inorganic carrier has an average particle diameter of 1 micron to 100 microns, a pore volume of 0.5 cm ³ /g to 10.0 cm ³ /g, and a surface area of 50m ² /g to 1000m ² /g. 11. The supported polyethylene catalyst according to claim 8, wherein the modification is aluminum modification: the inorganic carrier is impregnated with an aluminum salt solution, and the aluminum salt is selected from Al(NO ₃ ) ₃ , AlCl ₃ and Al ₂ (SO ₄ ) ₃ . 12. The supported polyethylene catalyst according to claim 8, characterized in that, the modification is titanium modification, which is modified by an impregnation method or a Cogel method. 13. The supported polyethylene catalyst according to claim 8, characterized in that the modification is fluorine modification: the inorganic carrier is co-impregnated with the fluorine-containing component. 14. a preparation method of supported polyethylene catalyst, it is the preparation method of the described supported polyethylene catalyst of claim 1-13 any one, is characterized in that, comprises the following steps: (1) Immerse the porous inorganic carrier in an aqueous solution containing inorganic chromium salts, the immersion time is 1-12h, the immersion temperature is 25-100°C, and then dried at 100-300°C for 5-20h, in 300°C-1000°C air Roasting in the air for 1-12h; (2) Immerse the product obtained in step (1) into the organic solution of organic chromium source and organic molybdenum source, the immersion time is 1-12h, the immersion temperature is 25-100°C, and then in a nitrogen atmosphere between 100-300°C Dry for 5-20 hours to finally obtain a supported polyethylene catalyst. 15. the preparation method of supported polyethylene catalyst according to claim 14 is characterized in that, in step (2), the organic solvent in described organic solution is ethanol, propanol, butanol, octanol, ethylene glycol Alcohol, propylene glycol, butylene glycol, octane glycol, pentane, hexane, heptane, octane, benzene, toluene, xylene or isomers of the above substances.