GB1598835A - Vanadium based catalysts for olefin polymerizations - Google Patents

Description

(54) VANADIUM BASED CATALYSTS FOR OLEFIN POLYMERISATION (71) We, MITSUBISHI CHEMICAL INDUSTRIES LIMITED, a company organised under the laws of Japan, of No. 5-2, Marunouchi 2-chome, Chiyoda-ku, Tokyo, Japan, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to vanadium based catalysts for olefin polymerisation, to a process for the preparation of such catalysts and to a process for the preparation of polyolefins by use of such catalysts.

It is well known in the art to prepare an olefin polymerization catalyst by treating a transition-metal compound with an organo metallic compound to synthesize a catalyst component insoluble in hydrocarbon solvents, and combining the said component with an organo metallic compound.

Other methods for synthesizing such catalysts are also known; one such method uses a halogen-containing compound of vanadium. However, we have found that the products obtained from any of these known methods are relatively low in activity, with a few exceptions; and in the polymer preparation process removal of residual catalyst is necessitated. It is generally acknowledged in the polymer industry that if the polymer yield with respect to the catalyst is increased and the catalyst removal step can be avoided an appreciable reduction of production cost would be possible.

According to the present invention we provide an olefin polymerization catalyst component comprising an organo aluminium compound and a solid catalyst component separated from a reaction mixture obtained by reducing a halogen-containing compound of vanadium, wherein the reduction is conducted in the presence of an ether, using an organo auminium compound.

The halogen-containing compounds of vanadium used in the preparation of catalyst components according to this invention include, as typical examples thereof, the compounds of the formula: VX4~,Y, (wherein X is a halogen atom, Y is an alkoxy group with 1 to 12, preferably 1 to 6 carbon atoms, or a trialkylsiloxy group (-OSiR group where R3 is an alkyl group with 1 to 12 carbon atoms), and n is a number defined by: 0 S n < 4), and the compounds of the formula: VOX3~,Y, (wherein xis a halogen atom, Y is an alkoxy group with 1 to 12, preferably 1 to 6 carbon atoms or trialkylsiloxy group (-OSiR33 group wherein R3 is an alkyl group with 1 to 12 carbon atoms), and m is a number defined by: 0 S m < 3). Examples of the compounds of the formula VX4~,Y, include vanadium tetrachloride, vanadium tetrabromide, vanadium tetraiodide, mono-n-butoxyvanadium trichloride and di-n-butoxyvanadium dichloride, and those of the compounds of the formula VOX3~,Y, include vanadyl trichloride, vanadyl tribromide, di-nbutoxychlorovanadyl, diisopropoxymonochlorovanadyl, mono-n-butoxydichlorovanadyl, monoisopropoxydichlorovanadyl and monotrimethylsiloxydichlorovanadyl.

Among these compounds, preferred for use in this invention are vanadium tetrahalide, vanadyl trihalide and alkoxydichlorovanadyl, and most preferred are vanadium tetrachlor ide, vanadyl trichloride and mono-n-butoxydichlorovanadyl.

Ethers which can be used in the process of this invention comprise compounds of the general formula: R1-O-R2 wherein R1 and R2, which may be the same as, or different from. each other, represent a hydrocarbon group with 1 to 12 carbon atoms, and Rl and R2 may be bonded together to form a ring, and such compounds include, for example, aliphatic ethers such as diethyl ether, diisopropyl ether, d-n-propyl ether, isopropylethyl ether, di-n-butyl ether, ethyl-n-butyl ether, di-n-amyl ether, di-n-octyl ether, di-n-decyl ether and di-n-dodecyl ether, alicyclic ethers such as tetrahydrofuran and tetrahydropyran, and aromatic ethers such as diphenyl ether and anisole. It is usually preferred to use an aliphatic ether with 1 to 12 carbon atoms, most preferably diisopropyl ether, di-n-butyl ether or di-n-octyl ether.

According to another aspect of the invention a process for preparing a catalyst in accordance with the invention comprises the reduction of a halogen-containing compound of vanadium in the presence of an ether by adding an organo aluminum compound. l ct us first describe the reduction accomplished by adding an organic aluminum compound, i.e. the method (I).

Organo aluminum compounds usable in the method of the invention include the compounds of the general formula: AlR4"X~n (wherein R4 is a hydrocarbon group with 1 to 12 carbon atoms, and X is a halogen atom or an alkoxy, trialkylsiloxy or dialkylamino group), and specific examples of such compounds are trialkylaluminum compounds such as triethylaluminum or triisobutyliluminum, dialkylaluminum compounds such as ethylaluminum monochloride, alkylaluminum sesquihalide such as ethylaluminum sesquichloride or ethylaluminum sesquihromidc. alkylaluminum dihalide such as cthylaluminum dichloride, alkoxyalkylaluminum such as cthylaluminum monoethoxide, and other compounds such as diethyl(trimethylsilorry)aluminum. diethyl(N,N-dimethylamino)aluminum or (C2H5)2AlN [Si(CH3)3]2, or mixtures of these compounds. Among them, alkylaluminum sesquihalide and alkylaluminum dihalide are preferred, and ethylaluminum dichloride is most preferred.

As regards the amounts of the respective components used in the reducing reaction, the ether is usually used in an amount of from 100 to 0.1 moles per mole of the halogen-containing compound of vanadium while the organic aluminum compound is used in an amount of from 10 to 0.05 moles per mole of the said vanadium compound, but these ranges are merely recommended and are not to be regarded as essential. It was determined, however. that the best results are obtained when using the ether component in an amount within the range of from 20 to 0.3 moles particularly 10 to 0.5 moles per mole of the halogen-containing compound of vanadium, and the organo aluminum compound in an amount within the range of 2 to 0.2 moles per mole of the said vanadium compound.

The method may be carried out by mixing a halogen-containing vanadium compound and an organo aluminum compound in the presence of an ether, followed by aging if necessary.

The incorporation of the ether component in the reaction system may be accomplished by several methods such as previously mixing the ether component with the halogencontaining vanadium compound or with the organo aluminum compound, or by mixing the three components simultaneously, but usually the first method or a method in which an ether compound is previously mixed with both the vanadium compound and the organic aluminum compound respectively is recommended for ease of practice. Since mixing of an ether and a halogen-containing vanadium compound or an organo aluminum compound produces a coordination compound, such mixing is accompanied with generation of heat, so that it is desirable to perform such mixing under cooling. The mixture may be heated after mixing.

The temperature employed for the mixing and reduction of the halogen-containing vanadium compound using the organo alminum compound is not restricted to any specific range, and may be effected over a wide temperature range from as low as -800C to a temperature of around 1500C, but usually best results are obtained by using a relatively low temperature. The preferred temperature range for this reaction is usually from -60"C to 90"C, most preferably 0 C to 50"C.

This mixing and reduction is preferably followed by aging. The aging temperature may be equal to the reaction temperature or higher, but in the event that no solid catalyst component is precipitated during the mixing and reduction, it is necessary to use a temperature at which the solid catalyst component is caused to precipitate as further described below (Procedure 2). The aging time is usually from 5 minutes to 3 hours but may be longer.

In carrying out the method of the invention, it is possible to use one or more of the reagents in the form as is directly for the reaction, but it is more practical to use them mixed with a suitable diluent, for example an inert hydrocarbon solvent such as hexane, heptane, benzene, toluene or the like. It is advantageous to use the same solvent as will be employed for the polymerization.

The method of the invention may be accomplished using the following two procedures: (1) The halogen-containing vanadium compound and organo aluminum compound are mixed and reacted in the presence of the ether to prepare a homogeneous solution, which solution is subjected to a heat treatment to produce the solid catalyst component.

(2) The solid catalyst component precipitates out as it is formed by the reacton of the halogen-containing vanadium compound and an organo aluminum compound in the presence of an ether.

It can not readily be determined whether the reaction will follow procedure (1) or procedure (2) as this will be dependent upon the mixing ratio of the halogen-containing vanadium compound and organo aluminum compound, the identity and amount of the ether used, reaction temperature, and identity and amount of the diluent used. Generally, however, a solution with a higher degree of homogeneity is obtained the greater the amount of ether and the lower reaction temperature used. Therefore, in practicing the method of the invention it is desirable to select a specific combination of the ether/vanadium compound/organo aluminum compound molar ratio and reaction temperature, and generally, it is preferred to use the lowest possible reaction temperature, greatest possible amount of ether and smallest possible amount of organo aluminum compound. For instance, when carrying out the reaction at an extremely low temperature such as -60 C, if the ether/halogen-containing vanadium compound molar ratio (hereinafter abbreviated as ether/V) is greater than 0.5, no limitation is placed on the amount of the organo aluminum compound used for the reaction, but when carrying out the reaction at around room temperature (about 25"C), it is desirable to maintain the molar ratio of organo aluminum compound/halogen-containing vanadium compound (hereinafter abbreviated as Al/V) within the range 0.05 to 1 when the ethers molar ratio is 0.5 to 1, within the range of 0.05 to 4 when the ether/V molar ratio is 1 to 3, and within the range of 0.05 the same value as the ether/V molar ratio. When the reaction temperature is fairly higher than room temperature, for example 60"C, it is desirable that the ethers molar ratio is greater than 3 and the Al/V molar ratio is within the range of 0.05 to half the ethers molar ratio.

There is also a tendency for the solid catalyst component to become more liable to separate out when using a smaller amount of ether, a greater amount of organo aluminum compound and a higher reaction temperature. Therefore, for carrying out the reaction according to the procedure (2), it is desirable to react the materials at a temperature higher than room temperature while maintaining the etherN/Al molar ratio within or close to the limits of the range of 1:1:0.5 to 1:1:5.

In following procedure (1), the solid catalyst component is precipitated during the aging treatment which is carried out under heating using an appropriate temperature usually in the range of from 30 to 100"C, preferably 50 to 80"C. In procedure (1), the aging temperature may be the same as the preceding mixing and reduction reaction temperature.

Of course, aging may also be carried out in procedure (2) and if it is, an elevated temperature will be used too.

Procedure (1) may be conducted, for example, as follows. When reacting vanadium tetrachloride and ethylaluminum dichloride in a toluene medium using di-n-butyl ether, if the reaction temperature is controlled to within the range of from 25 to 30"C and the Al/V ratio is fixed at 1.0, a homogenous solution is produced when keeping the ether/V molar ratio higher than 2. When the temperature of this homogenous solution is increased to within the range of from 50 to 800C, a purple precipitate is produced and a solid catalyst product is obtained therefrom.

Procedure (1) at least in the examples described herein has the advantages that it is possible to control the size of catalyst particles, to minimize the particle size distribution of the obtained polymer powder, making it possible to produce polymer having a bulk density higher than that obtained in said known processes.

The reaction mechanism of the ether in the reaction of a halogen-containing vanadium compound and an organic aluminum compound in accordance with this invention is unknown, but in view of the facts that the ether content in the produced solid is relatively small and that if the homogeneous solution is admixed with a Lewis acid such as titanium tetrachloride, tin tetrachloride. vanadium tetrachloride or aluminum chloride, a solid principally composed of vanadium is precipitated, it is presumed that the reduction and precipitation mechanism of the vanadium component is changed by the co-ordination of the ether.

The solid reaction mixture may then be subjected to separation by a suitable method such as decantation, filtration or centrifugal separation. The separated product is preferably dried under reduced pressure or washed with an inert hydrocarbon solvent such as hexane, heptane, benzene or toluene to remove the by-products and unreacted material and then used for olefin polymerization in combination with an organo aluminum compound mentioned hereinbelow. When washing the solid reaction product with an inert hydrocarbon solvent, it is recommended to use the same solvent as is employed for the polymerization reaction.

The organo aluminum compounds usable as co-catalyst in the polymerisation process of this invention include trialkyl aluminum such as trimethyl aluminum, triethyl aluminum, tripropyl aluminum, triisobutyl aluminum or trioctyl aluminum; dialkyl aluminum monohalide such as dimethylaluminum monochloride or diethylaluminum monochloride; alkylaluminum sesquihalide such as methylaluminum sesquichloride or ethylaluminum sesquichloride; and dialkylaluminum monoalkoxide such as diethylaluminum monoethoxide or diethylaluminum monomethoxide. Most preferred among these compounds are trialkyl aluminum and dialkylaluminum monohalide.

The ratio of the solid catalyst component and co-catalyst, as expressed in terms of AW molar ratio, is usually 0.1 to 100, preferably 1 to 10.

The thus prepared catalyst, incorporating both the solid catalyst component and organo aluminum compound is useful for the polymerization of olefins. Among the olefins which can be polymerized using a catalyst in accordance with this invention, are a-olefins such as ethylene, propylene, but-1-ene, pent-1-ene and oct-1-ene. These olefins may be mixed and copolymerized. The polymerization process of this invention is convenient for the preparation of the ethylene homo-polymers or ethylene copolymers containing other a-olefin units of up to 10% by weight, preferably up to 5% by weight. The polymerization can be accomplished either by solution polymerization or slurry polymerization carried out in an inert solvent or by gas-phase polymerization carried out in the absence of any solvent, but usually the polymerization is carried out in the presence of an inert solvent, an olefin or olefin mixture being supplied while maintaining the predetermined ranges of temperature and pressure in the polymerization systems.

Preferred examples of the inert solvents usable in this invention are aliphatic hydrocarbons such as pentane, hexane, heptane, octane or isooctane, alicyclic hydrocarbons such as cyclopentane or cyclohexane, and aromatic hydrocarbons such as benzene or toluene.

The polymerization reaction is usually carried out at a temperature within the range of from ambient up to 2000C and under a pressure within the range of atmospheric pressure to 100 atm.

It is to be noted that, in the polymerization process of this invention, the presence of hydrogen in the polymerization reaction zone is useful in controlling the molecular weight of the resulting polymer. The amount of hydrogen to be introduced into the reaction system is dependent upon the polymerization conditions, desired molecular weight of the polyolefin to be produced and other factors.

The catalysts described herein have extremely high catalytic activity, so that when olefins are polymerized according to the process of this invention, it is possible to dispense with the removal of the catalyst, which is industrially advantageous.

The process of this invention will now be further described in the following Examples, in which the values of Melt Index (hereinafter referred to as "MI") were determined according to ASTM-D1238-SYT, and polymerization activity K of the catalyst was measured from the following calculation: K = (amount of polymer, gr)/(amount of catalyst, gr) (hr) (ethylene pressure, kg/cm2).

EXAMPLE 1: (1) Preparation of solid catalvst component 100 ml of dehydrated and deoxygenated refined toluene and 45 mmol of vanadium tetrachloride were put into a 300-cc four-necked flask which had been dried and purged with purified nitrogen gas, and to this mixed solution was gradually added 135 mmol of di-n-butyl ether. Heat was evolved upon addition of the ether, but the solution was cooled to maintain its temperature below 30"C. After end of the ether addition, the mixed solution was agitated at room temperature for 30 minutes and then 45 mmole, calculated in terms of the aluminum component of ethylaluminum dichloride dissolved in toluene (the toluene solution amounting to 50% by volume of the mixed solution) added to the mixed solution by dropwise addition of the toluene solution. The reaction temperature was maintained at about 25"C. After completion of dropwise addition of the toluene solution, the mixed solution was aged at 25"C for one hour. The reaction solution had a slightly purplish brown color. This solution was further aged for an additional hour at 60"C, whereupon a purple precipitate was produced. The precipitate was washed repeatedly with n-hexane by means of decantation until no further elute came out. Then hexane was distilled off under reduced pressure to obtain 8.9 g of catalyst powder. This powder contained 28% by wt of vanadium.

(2) Polymerization 500 ml of purified normal hexane, 10 mg of the solid catalyst component prepared in (1) above and 0.2 mmol of triisobutyl aluminum acting as co-catalyst were fed into a dried and nitrogen-purged 1-litre capacity stainless steel autoclave, and the temperature in the autoclave was increased to 90"C. Refined hydrogen gas was added to the autoclave to adjust the total pressure to 2 kg/cm2 gauge, and then refined ethylene gas was introduced to commence the polymerization. Ethylene gas alone was added during the polymerization to maintain the total pressure at 12 kg/cm2 gauge, and the polymerization was carried out at 90"C for 1 hour. The polymerization reaction was stopped by introducing ethyl alcohol under pressure. After cooling, polyethylene powder was taken out of the autoclave, and after adding about 0.1% of bis(tertiary butyl) hydroxytoluene as stabilizer, said powder was dried by a drier at 80"C. 167 gr of white polymer powder with MI of 0.12 g/10 mm was obtained. The catalyst system activity K was 1,670.

Bulk density of the polymer powder (unit, g/cc, hereinafter referred to as "pub" was 0.37, and the particle size distribution of the obtained polymer powder, as measured by way of Rosin-Rammler's distribution parity, was 3.6. (Said parity is hereinafter represented by "n". The larger n is, the narrower is the distribution. R = 10bD;, where Do is particle size, R is weight fraction of the particles with sizes greater than Dp, and b is a constant).

EXAMPLES 2 - 6: Catalyst components were prepared according to the same procedure as Example 1-(1) except for changes in the proportions of the components. As the amount of the vanadium compound was fixed, the amounts of the ether and organo aluminum compound were different from those in Example 1-(1). The polymerization was carried out according to the procedure of Example 1-(2). The results are shown in Table 1.

EXAMPLES 7 - 8: Catalyst components were prepared according to the process of Example 1-(1) but by using benzene and normal hexane as diluents, and the polymerization was carried out by following the procedure of Example 1-(2), obtaining the results shown in Table 2.

EXAMPLES 9 - 11: Catalysts were prepared and polymerization carried out by following the process of Example 1 but by varying the kind of ether used in Example 1-(1); the results are shown in Table 3.

EXAMPLE 12: Polymerization was carried out according to the procedure of Example 1-(2); the solid catalyst component was prepared as described in Example 1-(1). The reaction was carried out by using ethylene gas previously mixed with but-1-ene as monomer and maintaining the but-1-ene ethylene molar ratio in the liquid phase at 0.23 during the polymerization reaction. The reaction gave 145 gr of white polymer powder with a melt index of 0.53.

Infrared spectroscopic analysis revealed that this product was a copolymer containing 2.2 side units derived from ethyl groups per 1,000 main chain carbon atoms.

TABLE 1 Example Proportions (molar ratio) Diluent Polymer MI K Genera- #B n No. Yield tion of VCl4 Butyl Ethylaluminum (g) g/10min solid in ether dichloride reaction 2 1 1 0.5 Toluene 175.0 0.09 1,750 Produced 0.30 2.2 3 1 1 0.3 Toluene 150.0 0.10 1,500 Produced 0.28 2.4 4 1 5 1 Toluene 204 0.29 2,040 Not Pro- 0.35 3.3 duced 5 1 4 1 Toluene 250 0.19 2,500 Not Pro- 0.40 4.2 duced 6 1 4 0.5 Toluene 221 0.21 2,210 Not Pro- 0.38 3.8 duced TABLE 2 Example Proportions (molar ratio) Diluent Polymer MI K Genera- #B n No. yield tion of VCl4 Butyl Ethylaluminum (g) g/10min solid in ether dichloride reaction 7 1 1 0.5 Benzene 131.0 0.15 1,310 Produced 0.30 2.2 8 1 1 0.5 Hexane 145 0.40 1,450 Produced 0.31 2.1 TABLE 3 Example Ether Proportions (mol. ratio) Diluent Polymer MI K Generation No. yield g/10min of solid in VCl4:ether:ethylaluminum (g) reaction dichloride 9 Isoamyl 1 3 : 1 Toluene 160 0.24 1,600 Not produced ether 10 N-butyl 1 : 3 : 1 Toluene 170 0.10 1,700 Not produced ethyl ether 11 N-octyl 1 . 3 . 1 Toluene 125 0.32 1,250 Not produced ether EXAMPLE 13: A catalyst component was prepared according to the method of Example 1-(1) by using vanadyl trichloride (VOCAL3) instead of vanadium tetrachloride. A deep bluish purple solid catalyst component was obtained. Polymerization according to the method of Example 1-(2) but using the said catalyst component gave 120 g of polymer with MI = 0.08 g/10 min.

Catalystic activity K was 1,200.

EXAMPLE 14: A catalyst component was prepared following the method of Example 1-(1) but using mono-n-butoxy-dichlorovanadyl tVOCl2 (OC4H9) instead of vanadium tetrachloride, and polymerization according to the method of Example 1-(2) but using this catalyst component gave 183 g of polymer with MI = 0.46. The catalystic activity K was 1,830.

EXAMPLE 15: 10 ml of dehydrated and deoxygenated refined hexane and 45 mmol of vanadium tetrachloride were put into a 300-cc four-necked flask which had been dried and purged with refined nitrogen gas, and to this solution was gradually added 45 mmol of di-n-butyl ether. This was followed by gradual addition of 30 mmol of ethylaluminum sesquichloride while maintaining the flask temperature at 25"C. A purple precipitate was produced with addition of the aluminum compound. After completion of the reaction, the reaction product was aged at 25"C for one hour and washed with normal hexane, and then hexane was distilled off under reduced pressure to obtain 9.2 gr of a purple solid product.

When this catalyst component was used in a procedure similar to that of Example 1-(2), 135 g of a corresponding polymer with MI of 0.21 was obtained. Catalystic activity K was 1,500.

EXAMPLE 16: A catalyst was prepared by following the same procedure as in Example 1-(1) except for the use of di-ethylaluminum monochloride instead of triisobutylaluminum as cocatalyst, and this catalyst was used in a procedure carried out as described in Example 1-(2).

There was consequently obtained 112 g of a polymer with MI = 0.22. The catalytic activity K was 1,120.

EXAMPLE 17: (1) Preparation of solid catalyst component 1 mol of ethylaluminum dichloride was diluted with the equal volume of refined ndrmal hexane, and then 1 mol of di-n-butyl ether was gradually added dropwise to this solution.

Heat was evolved due to coordination of the ether but the solution was cooled to maintain its temperature below 50"C.

200 cc of refined hexane and 20 mmol of vanadium tetrachloride were put into a dried and nitrogen-purged 300-ml-capacity four-necked flask, and then 30 mmol of said alkyl-aluminum-ether complex solution was gradually added dropwise into the mixed solution. The reaction temperature was maintained within the range 27 to 35"C and the reaction time was 30 minutes. A precipitate was produced which was initially brown in color but later changed into purple. This catalyst slurry was aged at room temperature for 2 hours and then washed with refined normal hexane until no more chloride compounds were detected in the eluate. Drying of the product under reduced pressure gave 4.4 gr of a catalyst component comprising 25.9% by wt of vanadium, 55.5% by wt of chlorine and 2.5% by wt of aluminum as determined by a chemical analysis.

(2) Polymerization A 1-litre capacity stainless autoclave was dried and purged with nitrogen and then fed with 500 ml of refined normal hexane, 7 mg of the catalyst component from 1 and 0.12 mmol of triisobutylaluminum, followed by pressurization with hydrogen. After raising the temperature to 900C, the partial pressure of hydrogen was set to 2 kg/cm2 gauge and then ethylene was further introduced with a partial pressure of 10 kg/cm2 gauge to commence the polymerization. Thereafter, ethylene gas alone was supplied to keep the total pressure constant and the polymerization was carried out for one hour. The polymerization was stopped by the introduction of ethanol under pressure, and the mixture was cooled.

Polyethylene was separated from the hexane solvent, and after adding about 0.1% by weight of bis-t-butylhydroxytoluene, the mixture was dried by a drier at 80"C, to give 96 gr of white powdery polyethylene with MI of 1.10. The catalyst activity K was 1,350.

EXAMPLE 18: 20 mmol of vanadium tetrachloride and 30 mmol of di-butyl ether complex of ethylaluminum dichloride were reacted at -60 C by using the apparatus of Example 17-(1).

A brown solution was obtained, but little solid product was formed. As the temperature rose gradually, a dark-brownish precipitate was produced. 2-hour aging of this product at 0 C, followed by the same treatment as in Example 1-(1), gave 4.5 g of a slightly brownish purple solid.

When this catalyst component was used in a procedure as described according in Example 17-(2), there was obtained 145 g of polyethylene with MI of 0.9. The activity K of the catalyst was 2,100.

EXAMPLE 19 A mixture of 10 mmol of vanadium tetrachloride and 10 mmol of vanadyl chloride was reacted with 30 mmol of butyl ether complex of ethyl aluminum dichloride according to the procedure of Example 17-(1) to give 5.2 gr of a dark-purplish catalyst arrangement having the composition of 26.2 wt% vanadium, 50.5% by wt chlorine and 2.9% by wt aluminum.

The procedure as described in Example 17-(2) but using this catalyst component gave 92.4 g of polyethylene with MI of 0.05. The catalyst activity K was 1,300.

EXAMPLE 20 A procedure was carried according to the method of Example 17-(2) using the catalyst component of Example 17-(1). The reaction was carried out using ethylene gas previously mixed with but-1-ene as monomer and by maintaining the but-1-ene/et

Claims (21)

WHAT WE CLAIM IS:

1. An olefin polymerization catalyst comprising an organoaluminium compound and a solid catalyst component separated from a reaction mixture obtained by reducing a halogen-containing compound of vanadium, wherein the reduction is conducted in the presence of an ether, using an organoaluminium compound.

2. A catalyst according to Claim 1, wherein the ether is a compound of the general formula R1-O-R2 in which R1 and R2, may be the same or different and represent a hydrocarbon group having 1 to 12 carbon atoms, or Rl and R2 together form a ring.

3. A catalyst according to Claim 1 or 2, wherein the ether is used in an amount of 0.1 to 100 moles per mole of the halogen-containing compound of vanadium.

4. A catalyst according to Claim 4, wherein the solid catalyst component is obtained by a heat treatment of the reaction mixture prepared as a homogeneous solution.

5. A catalyst according to Claim 4, wherein the heat treatment is carried out at a temperature of from 30 to 100"C.

6. A catalyst according to Claim 4, wherein the reduced product precipitates out as it is formed to provide the solid catalyst component.

7. A catalyst according to anyone of Claims 3 to 6, wherein the halogen-containing compound of vanadium is vanadium tetrahalide, vanadyl trihalide or an alkoxydichlorovanadyl.

8. A catalyst according to anyone of Claims 3 to 7, wherein the reduction is carried out in the presence of hydrocarbon solvent.

9. A process for the preparation of an olefin polymerization catalyst comprising reducing a halogen containing compound of vanadium in the presence of an ether, by using an organoaluminium compound, obtaining the reduced product as a solid precipitate and admixing the solid precipitate with an organoaluminium compound.

10. A process according to Claim 9, wherein the ether is a compound of the general formula R -O-R2 in which R1 and R2, may be the same or different and represent a hydrocarbon group having 1 to 12 atoms, or Rl and R2 together form a ring.

11. A process according to Claim 9 or 10, wherein the ether is used in an amount of 0.1 to 100 moles per mole of the halogen-containing compound of vanadium.

12. A process according to Claim 11, wherein the solid catalyst component is obtained by a heat treatment of the reaction mixture prepared as a homogeneous solution.

13. A process according to Claim 12, wherein the heat treatment is carried out at a temperature of from 30 to 100"C.

14. A process according to Claim 11, wherein the reduced product precipitates out as it is formed to provide the solid catalyst component.

15. A process according to anyone of Claims 11 to 14, wherein the halogen-containing compound of vanadium is vanadium tetrahalide, vanadyl trihalide or an alkoxydichlorovanadyl.

16. A process according to anyone of Claims 11 to 15, wherein the reduction is carried out in the presence of a hydrocarbon solvent or halogenated hydrocarbon solvent.

17. A catalyst obtained by the process of anyone of Claims 11 to 16.

18. A process for the preparation of polyolefins which comprises polymerising olefins using a catalyst as defined in anyone of Claims 1 to 8, and 17.

19. A catalyst according to Claim 1, substantially as described with reference to anyone of the Examples herein.

20. A process for the preparation of a catalyst according to Claim 9, substantially as herein described with reference to anyone of the Examples herein.

21. A process for the polymerization of olefins according to Claim 18, substantially as described with reference to anyone of the Examples herein.