RU2682163C1 - Method for preparation of vanadium magnesium polymerization catalyst of ethylene and copolimerization of ethylene with alpha olefines - Google Patents

Abstract

FIELD: chemistry.SUBSTANCE: invention relates to a method for producing catalysts for polymerization of ethylene and copolymerization of ethylene with α-olefins, more specifically to supported Ziegler-type catalysts containing in their composition transition metal compound on magnesium-containing carrier. Catalyst for production of polyethylene and copolymers of ethylene with alpha-olefins with broad molecular weight distribution, containing transition metal compound on magnesium-containing carrier, prepared by interaction of organomagnesium compound solution with chlorinating agent phenyltrichloromethane PhCClwith a molar ratio of PhCCl/Mg ≥ 1.0 at a temperature of 15–45 °C, followed by treatment of the support with an alkyl aluminum chloride and application of the vanadium compound, as the organomagnesium compound a solution of butyl magnesium chloride in ether RO is used, where R = i-amyl or butyl, into which, prior to the introduction of the chlorinating agent, the modifier is introduced – aliphatic ester – ethyl acetate (EA) at a molar ratio of EA / Mg = 0–0.5.EFFECT: high catalyst activity in the processes of suspension polymerization of ethylene and copolymerization of ethylene with αolefins and production of polymers with wide MWD, narrow and adjustable particle size distribution and increased bulk density (>0,35 g/cm).1 cl, 15 ex, 1 tbl

Description

The invention relates to a method for producing catalysts for the polymerization of ethylene and copolymerization of ethylene with α-olefins, and more particularly, to supported Ziegler-type catalysts containing a transition metal compound on a magnesium-containing support.

Various methods are known for preparing supported Ziegler-type catalysts. However, only some of these methods allow you to control the morphology of the particles of the carrier and, accordingly, of the catalyst (particle size, shape and density, particle size distribution). In the case of suspension and gas phase polymerization, the morphology of the catalyst particles determines the morphology of the polymer particles formed on them. Obtaining a polymer powder with a certain average particle size, with a narrow particle size distribution, with an increased bulk density is an important condition for the polymerization process technology, and for this it is necessary to obtain catalysts with a narrow particle size distribution and improved morphology.

A known method of producing a supported catalyst for the polymerization of ethylene and copolymerization of ethylene with alpha-olefins containing a transition metal compound (TiCl ₄ , VOCl ₃ , VC ₄ ) on a support of MgCl ₂ ⋅mR ₂ O composition by applying a transition metal compound to a support [RU 2064836 , B01J 31/38, 08/10/96]. In this case, the carrier is obtained by the interaction of an organomagnesium compound (MOS) with the composition Mg (C ₆ H ₅ ) ₂ ⋅nMgCl ₂ ⋅mR ₂ O (n = 0.37-0.7, m = 2, R ₂ O is an ether with R = i-Am, n-Bu) with carbon tetrachloride. The catalyst prepared by this method allows one to obtain polymers with a narrow controlled particle size distribution and increased bulk density while maintaining high activity in the processes of suspension and gas-phase polymerization of ethylene and copolymerization of ethylene with α-olefins.

The main disadvantage of this method is the use of carbon tetrachloride as a chlorinating agent: the reaction of carbon tetrachloride with an organomagnesium compound proceeds very intensively with high heat generation and is difficult to control, especially when preparing catalysts in large quantities.

The closest solution to the problem posed in this application is a method for producing a catalyst, according to which a supported catalyst containing vanadium tetrachloride (oxytrichloride) on a magnesium-containing support is prepared by reacting a soluble organomagnesium compound of the composition MgPh ₂ ⋅nMgCl ₂ RmR ₂ O, into which the alkyl aromatic ether is preliminarily introduced, with a chlorinating agent feniltrihlormetanom (PhCCl ₃₎ at a molar ratio of ₃ RhSSl / MgR ₂ ≥1.0, followed by treatment with alkyl aluminum carrier and applying the compound vanadium. This method allows the synthesis of highly active vanadium-magnesium catalysts with an adjustable particle size in the range from 20 to 6 μm with a narrow particle size distribution (SPAN <0.9), which allows to obtain polyethylene with a wide molecular weight distribution (MMP) [RU 2502560, B01J 31 /36,2012.08.27].

The main disadvantage of the above methods is the use of the composition MgPh ₂ ⋅nMgCl ₂ ⋅mR ₂ O as an organomagnesium compound obtained at elevated temperatures by the reaction of metallic magnesium with chlorobesol in the presence of ether (R ₂ O), as well as its use as a modifier in the synthesis of a carrier alkyl aromatic ester, in particular dibutyl phthalate (DBP).

The basis of the claimed invention is the task of developing a process for the preparation of catalysts using an organomagnesium compound MOC, which does not contain chlorine-containing aromatic hydrocarbons, and also precludes the use of alkyl aromatic ether in the synthesis of MgCl ₂ -containing carrier.

EFFECT: high activity of the catalyst in the processes of suspension polymerization of ethylene and copolymerization of ethylene with α-olefins and the production of polymers with a wide MMP, a narrow and controlled particle size distribution and increased bulk density (> 0.35 g / cm ³ )

This problem is solved in that for the preparation of the catalyst using a new method of preparing a magnesium-containing carrier.

A catalyst for the production of polyethylene and ethylene-alpha-olefin copolymers with a wide molecular weight distribution, containing a transition metal compound on a magnesium-containing support, is prepared by reacting a solution of an organomagnesium compound with a chlorinating agent phenyltrichloromethane PhCCl ₃ at a molar ratio PhCCl ₃ / Mg ≥ 1.0 at a temperature of 15- 45 ° C, followed by treatment of the support with alkylaluminum chloride and application of a vanadium compound, butyl magnesium chloride solution is used as an organomagnesium compound ether in ether R ₂ O, where: R = i-amyl or butyl, into which the modifier — aliphatic ester — ethyl acetate (EA) is introduced before the administration of the chlorinating agent at a molar ratio EA / Mg = 0-0.5.

A magnesium-containing carrier is obtained by reacting a solution of an organomagnesium compound, which is butyl magnesium chloride in an ether solution of R ₂ O, where: R = i-amyl or butyl, with a complex product that causes the conversion of the organomagnesium compound into a solid magnesium-containing carrier. The following reagents are used sequentially as such a product used to convert an organomagnesium compound to a solid magnesium-containing support: ethyl acetate (EA) at a molar ratio EA / Mg = 0-0.5 and phenyltrichloromethane PhCCl ₃ at a molar ratio PhCCl ₃ / MgR ₂ ≥1.0. The solid magnesium-containing support obtained in this way is treated with an organoaluminum compound R ″ _x AlCl _3-x , where: R ″ = alkyl or alkoxy - group, x = 1-2 with the ratio Al / Mg = 0.8-2.6.

The catalyst is obtained by subsequent treatment of a suspension of a carrier in a hydrocarbon solvent with a solution of vanadium compounds (VCl ₄ , VOCl ₃ ) in carbon tetrachloride.

The proposed method provides highly active catalysts (yield ≥ 10 kg PE / g cat) with an average particle size of ≈ 10 μm and a narrow particle size distribution.

During the polymerization of ethylene, polyethylene with a high bulk density (more than 0.34 g / cm ³ ) and a narrow particle size distribution is formed on this catalyst.

The polyethylene obtained using the proposed vanadium-magnesium catalyst (VMC) has a wide molecular weight distribution.

The catalysts are used for the polymerization of ethylene or the copolymerization of ethylene with α-olefins in combination with a cocatalyst - aluminum trialkyl, mainly triisobutylaluminum or triethylaluminum.

The polymerization is carried out in suspension mode at a temperature of 50-100 ° C in a hydrocarbon solvent, for example, hexane, heptane, and a pressure of 2-40 atm. As a regulator of the molecular weight of the polymer, hydrogen is used in an amount of 5-50 vol. % In the copolymerization of ethylene with α-olefins, propylene, butene-1, hexene-1, 4-methyl-pentene-1 and other higher α-olefins are used.

The invention is illustrated by the following examples.

Example 1

220 ml of a solution of BuMgCl in dibutyl ether (RHEED) with a concentration of 0.85 mol / L, obtained by the interaction of magnesium metal with butyl chloride in dibutyl ether (BuCl / Mg = 1.1, RHEED / Mg = 6.6), is loaded into a stirred reactor. At 20 ° С, a solution of PhCCl (31.2 ml) (PhCCl ₃ / Mg = 1.2) in RHEED (30.0 ml) was dosed at 20 ° С for 1.5 h. The reaction mixture was then heated to 60 ° С for 30 min and kept at this a temperature of 1 h. The mother liquor is removed and the precipitate formed is washed with heptane 4 times in 250 ml at a temperature of 50 ° C.

To the resulting suspension of a magnesium-containing product in 150 ml of heptane, 293 ml of a 1.0 M solution of diethylaluminium chloride in heptane (AlEt ₂ Cl / Mg = 1.2) was added, the reaction mixture was heated to 45 ° C and kept under stirring for 2 h, then the solid precipitate was sedimented and washed heptane at a temperature of 45 ° C 5 times in 200 ml. 25.5 g of a powdered magnesium-containing support are obtained in the form of a suspension in heptane with an average particle size of 17.8 μm.

To a suspension of a carrier in 150 ml of heptane at room temperature, 26 ml of a solution of vanadium tetrachloride in carbon tetrachloride with a vanadium content of 0.034 g / ml are added. The resulting suspension was heated to 60 ° C and kept under stirring for 1 h, then the solid precipitate was sedimented and washed with heptane at a temperature of 45 ° C 4 times 200 ml. A supported catalyst is obtained with a vanadium content of 3.6 wt%, with an average particle size of 18 microns.

Ethylene is polymerized in a 0.85 liter steel reactor equipped with a stirrer and a thermostatic jacket. As a solvent for polymerization, heptane (250 ml) and cocatalyst triisobutylaluminium (TIBA) with a concentration of 4.8 mmol / L are used. The polymerization is carried out at a temperature of 80 ° C, an ethylene pressure of 9 atm., A hydrogen pressure of 0.5 atm. in the presence of 1-hexene (5 ml) with a concentration of 0.16 mmol / L for 2 hours. The polymerization results are shown in the table.

Example 2

The catalyst was prepared under the conditions of Example 1, except that first ethyl acetate (EA) (3.63 ml) (ethyl acetate / Mg = 0.2 (mol.)) Was added to the MOC solution at a temperature of 20 ° C for 20 minutes. and the mixture was kept for 10 minutes, and then a solution of PhCCl ₃ in RHEED was dosed to the reaction mixture. The resulting carrier is treated with a solution of vanadium tetrachloride in carbon tetrachloride at a rate of 3.5 wt.%. The catalyst contains 3.5 wt% vanadium and has an average particle size of 13 microns.

The polymerization of ethylene is carried out under the conditions of example 1, except that 1-hexene is not added. The polymerization results are shown in the table. Example 3

The catalyst is prepared under the conditions of Example 2, except that the MOC treatment is carried out at a molar ratio EA / Mg = 0.30 and the solid magnesium-containing product is treated with a 1.0 M solution of diethylaluminium chloride in heptane at the ratio AlEt ₂ Cl / Mg = 0.8, and the resulting support is treated with a tetrachloride solution vanadium in carbon tetrachloride at a rate of 1.4 wt%. The catalyst contains 1.3 wt% vanadium and has an average particle size of 10 μm.

The polymerization of ethylene is carried out under the conditions of example 1. The polymerization results are shown in the table.

Example 4

The catalyst was prepared under the conditions of Example 3, except that a solid magnesium-containing product was treated with a 1.0 M solution of diethylaluminium chloride in heptane at a ratio of AlEt ₂ Cl / Mg = 1.2, and the resulting support was treated with a solution of vanadium tetrachloride in carbon tetrachloride at a rate of 2.5 wt%. The catalyst contains 2.3 wt% vanadium and has an average particle size of 10 μm.

The polymerization of ethylene is carried out under the conditions of example 1. The polymerization results are shown in the table.

Example 5

The catalyst was prepared under the conditions of Example 3, except that the support obtained was treated with a solution of vanadium tetrachloride in carbon tetrachloride at a rate of 3.0 wt%. The catalyst contains 3.2 wt% vanadium and has an average particle size of 10 μm.

The polymerization of ethylene is carried out under the conditions of example 1. The polymerization results are shown in the table.

Example 6

The catalyst was prepared under the conditions of Example 3, except that the solid magnesium-containing product was treated with DEAC at a molar ratio of AlEt ₂ Cl / Mg = 1.8 and a solution of vanadium tetrachloride in carbon tetrachloride at a rate of ≈ 3.0 wt. % The catalyst contains 3.0 wt. % vanadium and has an average particle size of 10 microns.

The polymerization of ethylene is carried out under the conditions of example 1. The polymerization results are shown in the table. Example 7

The catalyst was prepared under the conditions of Example 3, except that the solid magnesium-containing product was treated with DEAC at a molar ratio of AlEt ₂ Cl / Mg = 2.6 and a solution of vanadium tetrachloride in carbon tetrachloride at a rate of ≈ 4.0 wt%. The catalyst contains 4.1 wt% vanadium and has an average particle size of 10 μm.

The polymerization of ethylene is carried out under the conditions of example 1. The polymerization results are shown in the table. Example 8

The catalyst was prepared under the conditions of Example 3, except that the solid magnesium-containing product was treated with a solution of vanadium tetrachloride in carbon tetrachloride at a rate of ≈ 4.5 wt%. The catalyst contains 4.7 wt% vanadium and has an average particle size of 10 μm.

The polymerization of ethylene is carried out under the conditions of example 1. The polymerization results are shown in the table.

Example 9

The catalyst was prepared under the conditions of Example 2, except that the MOC was treated at a molar ratio EA / Mg = 0.35 and the solid magnesium-containing product was treated with a 1.0 M solution of diethylaluminium chloride in heptane at a ratio of AlEt ₂ Cl / Mg = 1.2, and the resulting support was treated with a tetrachloride solution vanadium in carbon tetrachloride at a rate of 3.0 wt%. The catalyst contains 2.7 wt% vanadium and has an average particle size of 10 μm.

The polymerization of ethylene is carried out under the conditions of example 1. The polymerization results are shown in the table. Example 10

The catalyst was prepared under the conditions of Example 9, except that a solid magnesium-containing product was treated with a 0.7 M solution of ethyl aluminum sesquichloride (El ₃ Al ₂ Cl ₃ ) in heptane at an Al / Mg ratio of 1.8, and the resulting support was treated with a solution of vanadium tetrachloride in carbon tetrachloride based on 2.5 wt%. The catalyst contains 2.3 wt% vanadium and has an average particle size of 10 μm.

The polymerization of ethylene is carried out under the conditions of example 1. The polymerization results are shown in the table. Example 11

The catalyst was prepared under the conditions of Example 10, except that instead of vanadium tetrachloride, vanadium oxytrichloride was used. The catalyst contains 2.3 wt% vanadium and has an average particle size of 10 μm.

The polymerization of ethylene is carried out under the conditions of example 1. The polymerization results are shown in the table.

Example 12

The catalyst was prepared under the conditions of Example 2, except that the MOC treatment was carried out at a molar ratio EA / Mg = 0.36 and the solid magnesium-containing product was treated with DEAC at a molar ratio AlEt ₂ Cl / Mg = 1.4. The catalyst contains 2.3 wt% vanadium and has an average particle size of 10 μm.

The polymerization of ethylene is carried out under the conditions of example 1, except that the solvent is hexane, the pressure of ethylene is 7.5 bar, the pressure of hydrogen is 0.6 bar, the concentration of hexene-1 is 0.13 mol / l, and the temperature is 82-84 ° C. The polymerization results are shown in the table.

Example 13

The catalyst is obtained under the conditions of example 2, except that the processing of the MOC is carried out at a molar ratio EA / Mg = 0.4. The catalyst contains 3.1 wt% vanadium and has an average particle size of 11 μm.

The polymerization of ethylene is carried out under the conditions of example 1. The polymerization results are shown in the table.

Example 14

The catalyst was prepared under the conditions of Example 13.

Polymerization of ethylene is carried out under the conditions of Example 1, except that instead of TIBA, TEA (1.3 mmol / L) is used as a cocatalyst. The polymerization results are shown in the table.

Example 15

The catalyst is obtained under the conditions of example 2, except that the processing of the MOC is carried out at a molar ratio EA / Mg = 0.5. The catalyst contains 3.1 wt% vanadium and has an average particle size of 9.0 μm.

The polymerization of ethylene is carried out under the conditions of example 1. The polymerization results are shown in the table.

It can be seen from the examples presented in the table that polymers with a high yield (up to 19.3 kg / g cat), with a wide molecular weight distribution (ratio of melt indices IR (21.6) / IR (5) = 18-29) and with improved morphology ( bulk density PE ≥ 340 g / l, narrow particle size distribution (SPAN ≤ 1)) can be obtained by using vanadium-magnesium catalysts (BMC) for the polymerization of ethylene, obtained by applying vanadium compounds to magnesium-containing carriers synthesized by the sequential interaction of magnesium ether solution organic compound BuMgCl with ethyl acetate (at a molar ratio EA / Mg from 0 to 0.5) and chlorinating PhCCl ₃ (PhCCl ₃ / Mg ≥1.0), followed by treatment of the solid magnesium-containing product with an organoaluminum compound (AlEt ₂ Cl or Et ₃ Al ₂ Cl ₃ ) . _. The optimal molar ratios in the synthesis of VMCs are as follows: EA / Mg = 0.30-0.36 PhCCl ₃ / Mg = 1.1, Al (AlEt ₂ Cl or Et ₃ Al ₂ Cl ₃ ) / Mg = 0.8-1.8, vanadium content 2.3-3.2 wt%. Under these conditions, the synthesis of the polymers obtained with the highest bulk densities (340-423 g / l) and maximum outputs (10-19 kg / g cat) and the content of 1-hexene (up to 5 CH _3/1000 C).

(выход, г ПЭ/ г катализатора) ^{1) the} average particle size of the catalyst (d) calculated from the average particle size of the polymer (D) according to the formula:

(yield, g PE / g catalyst)

²⁾ PE melt index at a load of 5 kg (190 ° C)

^{3) the} ratio of the melt indices at loads of 21.6 and 5 kg

⁴⁾ bulk density of polymer powder

⁵⁾ ethylene pressure 7.5 bar, hydrogen pressure 0.6 bar, [1-hexene] = 0.13 mmol / l, polymerization temperature 82-84 ° C

⁶⁾ triethylaluminum cocatalyst (1.3 mmol / L)

Claims (1)

A method of preparing a vanadium-magnesium catalyst for producing polyethylene and ethylene-alpha-olefin copolymers with a wide molecular weight distribution containing a transition metal compound on a magnesium-containing support obtained by reacting a solution of an organomagnesium compound with a chlorinating agent phenyltrichloromethane PhCCl ₃ at a molar ratio PhCCl ₃ / Mg ≥ 1.0 at a temperature of 15-45 ° C, followed by treatment of the carrier with aluminum alkyl chloride and the application of a vanadium compound, characterized in that as organomine compounds use a solution of butyl magnesium chloride in ether R ₂ O, where R = i-amyl or butyl, into which the modifier - aliphatic ester - ethyl acetate (EA) is introduced before the introduction of the chlorinating agent at a molar ratio EA / Mg = 0-0.5.