CS195283B2 - Method of producing catalyst component - Google Patents

Description

The present invention relates to a process for the production of a catalyst component consisting of a reaction product of a transition metal chloride and a titanium tetrachloride dispersed on a support having a large specific surface area and usable in combination with an alkyl aluminum compound for the polymerization of α-olefins, particularly ethylene.

It is known to use catalytically active titanium halides in the polymerization of α-olefins under low pressure. These halides are prepared by the reduction of te, trahalide of titanium with alkyl aluminum or alkyl halide compounds. The reaction is generally carried out under an inert atmosphere and in the presence of an inert solvent. The catalyst thus obtained is subsequently used together with the alkyl compounds to polymerize α-olefins in suspension in an organic solvent at an appropriate monomer pressure.

However, the titanium halides exhibit impurities due to the presence of aluminum compounds and do not show very good catalytic activity, so that the resulting polymer requires expensive purification operations to remove catalytic residues.

Furthermore, a catalyst for the polymerization of α-olefins containing mixed crystals of TiCl 2 or TiCl 2 metal halides in combination with alkyl-aluminum compounds is known.

Recently, processes have been proposed in which titanium halides are deposited on inorganic substances to provide polymerization catalysts with improved efficiency. Carriers used include, for example, oxide or magnesium hydroxide; however, it must be taken. The catalytic activity of the titanium compound carried on these materials varies considerably depending on the chemical nature of the surface of the compounds. For this reason, these compounds must in many cases be subjected to treatment with Grignard reagents, alkyl aluminum compounds or hydrogen for the purpose. improving their effectiveness.

SUMMARY OF THE INVENTION The present invention provides a process for the preparation of a catalyst component for the polymerization of α-olefins formed by the reaction product of a transition metal chloride and a titanium tetrachloride of the formula

MCI · ,. n TiCb where

M is vanadium, manganese, cobalt or iron and n is a number equal to M

135283 deposited on a material with a large specific surface consisting in that the transition metal compound is deposited on the support by solvent impregnation in the lowest valence stage, the mixture is heated to reflux in titanium tetrachloride, then the excess titanium tetrachloride is removed.

The reaction products described are very chemically stable since titanium tetrachloride and transition metal chloride are isostructured; moreover, they contain titanium in the optimum valence stage for the best catalytic efficiency.

In the process according to the invention, the carrier, previously dehydrated by heat treatment, is impregnated with a low-valency transition metal compound, particularly at a zero valence stage, for example in the form of a carbonyl metal derivative dissolved in a hydrocarbon solvent and then in titanium tetrachloride. .

The zero-valent transition metal compound may also contain ligands other than carbonyl, for example, alkyl, cyclopentadienyl, olefinic and nitrosyl groups, and so on.

Volatile substances evolve during the process, especially in the case of metal carbonyl compounds, which develop carbon monoxide and oxidize the metal while reducing titanium tetrachloride to titanium tetrachloride according to the equation

M (COjp + nTICU - * MCl _n . NTICb + p CO, where denotes the number of carbonyl groups, n denotes the valence degree achieved by the transition metal M during oxidation with titanium tetrachloride.

The material used as the carrier is selected from the group of materials having a large specific surface area, such as oxides of elements belonging to Class II. to IV. groups of the periodic system elements.

The transition metal is used in an amount ranging from 0.1 to 10, preferably 1 to 3% by weight, based on the weight of the carrier. Preferably, the material used as the support is selected from silica, silica and alumina, ZnO2, MnO, TiO2, CaO.

As previously stated, the catalyst systems of the present invention do not need to be pretreated since the efficiency of the catalyst systems of the present invention is high and homogeneous, although the chemical nature of the support is subject to variation; however, said carriers may also be pretreated with Grignard reagents or aluminum alkyl halides to further improve the properties of the compounds.

In any case, the efficiency of the catalyst systems of the present invention in polymerization reactions is higher than in TiCla-treated carrier processes, while the other conditions remain the same. The catalysts of the present invention exhibit good properties in the presence of hydrogen and cause a narrow molecular weight distribution in the case of ethylene polymerization.

The polymerization reaction is carried out in a manner known per se at temperatures ranging from 0 to 200 ° C at pressures of 5 to 5 MPa.

In the following examples, the solvent, the organometallic compound [Al (—C4H9] 3 at 0.2 vol%] and the transition metal reaction products prepared as described above are fed to an autoclave thermostatized at 85 ° C. These standard conditions apply to all procedures described in the following examples (standard polymerization), and the polymers obtained were vacuum dried to constant weight before evaluation in yield.

The following examples are provided for convenience only and do not limit the scope of the invention in any way.

Example 1

100 g “Low Alumina” SiO2 / Al2O3, SA = 400 m ² / g ,. was refluxed in boiling xylene to azeotropically remove water. To the product, dried, filtered under nitrogen and washed with hexane, was added 3 g of tetracarbonyl-vanadium cyclopentadlenyl, V (CO) 4 Cp, in 200 mL of hexane. This solvent was removed in a rotary evaporator and the yellow air-sensitive substance was refluxed for six hours after being suspended in 200 mL of TiCl 4. During this time, the substance turned dark purple. It was then filtered, washed several times with hexane and dried in vacuo.

The analysis showed the following composition

Ti 7,30%

V 0,40%

Cl 12.54%

When polymerizing ethylene under a partial pressure of H 2 = 1.3 MPa, and C 2 H 4 - 0.8 MPa, 240 mg of this catalyst were used.

500 g of polyethylene MF21.6 = 1, [η] Srn = 4.6 dl / g, and containing 36 ppm Ti + V, where the Ti content was about 33 ppm, were obtained.

Example 1 a d 2

Same SIO2-Al2O3 used in the example

195283 5 was refluxed under the same conditions, only with titanium tetrachloride. After the same treatment, the air-sensitive white material showed the following analytical results

Ti 4.10 '%

Cl 7.98%. 224 mg of this catalyst gave, under the same polymerization conditions as in the previous example, 60 g of a MFa-containing polymer, 6 - 0.2, [η] ε in = 8.6 dl / g and a Ti content of 150 ppm.

Example 3 g S1O2 (> 99%), SA = b = 400 m2 / g, was dehydrated, subjected to azeotropic distillation with xylene as described in the previous example, treated with 0.65 g V (CO) 4 Cp in hexane (50 ml). ml) and then boiled. after removal of the hydrocarbon solvent in liquid TiCl4 (50 mL) for a time and as described in Example 1. The color of the catalyst thus obtained was dark violet. Analysis of the mixture showed the following values:.

Ti 4,65%

V. 0,40%

Cl 8.24%

105 mg of the catalyst thus obtained were used in standard polymerization under a relative pressure of H 2 / C 2 H 4 = 1/1 MPa. 102 g of polyethylene were obtained as described above; the MFz.e value - 0.3 and the Ti + V content corresponded to 52 ppm, where the content. You did. 46 parts million.

Example 4 g of SiO 2 / Al 2 O 3 of the same type as in Examples 1 and 2 were dried in a muffle furnace at 400 ° C for 24 hours and subsequently impregnated with 4.0 g Mna (CO) 10 in 200 ml hexane.

The solvent was removed in a rotary evaporator and the orange-yellow solid was refluxed in boiling TiCl 3 for 6 hours.

The filtered violet material, washed with hexane and dried under vacuum, showed the following analysis:

Ti 5,72%

Mn 1,35%

Cl 12,60%

169 mg of this product used in standard; polymerization tests at

1.3 MPa H2 and 0.8 MPa C2H4 yielded 151 g 'of polyethylene having a M-F2.16 of 0.350, MFzI, 6 = 15.684, MFzI / Mf2, 16 ==44, [η] - 3.3 dl / g and 79 ppm Mn, + Ti, where Ti - 64 ppm.

Example 5 g of finely divided MgO, dried in a muffle furnace at 400 ° C overnight, was reacted with 1.5 g of CO 2 CO 3 in 10.0 ml hexane. The solvent was then removed on a rotary evaporator and the residue was refluxed under a nitrogen atmosphere in 100 ml of TiCl4 for 8 hours.

The violet powder was hot filtered, washed several times with hexane and dried in vacuo. The product had the following composition:

Ti. 3.70%

Co 1.55%. Cl 31.15% mg of the product thus obtained was used in standard polymerization under 1 MPa hydrogen pressure and 2 MPa C2 H 4 pressure. This procedure gave 250 g of polyethylene, MF 2.16-0.869, MF21.6-34.97, MF21, e / MF2.16 = 40.2, [η] decalin - 1.92 dl / g and a Ti + content. Co = where Ti = 4.6 ppm.

Example 6

A sample of commercial MgO was hydrated in water at 80 ° C for 4 hours and then dried in a muffle furnace at 400 ° C in air for 24 hours.

mg of the MgO so treated was impregnated with V (CO) 4 Cp (1.2 g) in hexane (100 mL) and the solvent was removed on a rotary evaporator. The dry residue was then refluxed in boiling TiCl 4 (100 mL) for 4 hours.

The violet produt was filtered, washed and dried under vacuum. Its composition was as follows:

Ti 3,31%

V. 0,58 '%

Cl,. 35,23%

1852B3 mg of this catalyst was used in standard polymerization under relative hydrogen pressure / CH 2 = 1/1 MPa. 235 g of polyethylene of values were obtained

MF, 2, i6 = 1.203, toF2 _{1 (6} = 49.03,

MF, _{21) 6} / Mf ₂ , ₁₆ = 40.8, [η] dlcaline - 1.90 dl / g and containing Ti + V, where Ti was 2.8 ppm.

Example 7 g of MgO treated according to Example 6 was refluxed in boiling TiCl 2 (100 mL) for 4 hours. The white solid was then filtered, washed and dried under vacuum. Its composition was as follows:

Ti 1,43%

Cl% 31.62 mg of catalyst were used for comparison in the standard polymerization, the process according to Example 8. Yield: 81 g of polyethylene, having a value MF _{2) 16} = 1.81, MF ₂ and ₆ = 44,

MF _{21 16} = 36.3, [η] decaine = 2.73 dl / g and Ti content = 7.4 ppm.

EXAMPLE 8 g of the S102 type used in Example 3 were dehydrated by azeotropic distillation with xylene and treated with 2 ml of AlEtCl2 in 100 ml of hexane. 1.0 g of V (CO) 4 Cp was then added to the suspension and the solvent was subsequently removed on a rotary evaporator. The material so obtained was refluxed for 6 hours with boiling TICU. Filtration, washing with hexane and drying in vacuo gave a violet product having the following composition:

Ti 2,97%

V 0,86% '

AI 1,90%

Cl 8.59%

192 mg of the catalyst thus obtained were used by standard polymerization at a relative pressure of H2 / C2H4 - 1/10 bar. To give 96 g of polyethylene having a MF _{2, 16} = 0.335, MF _{21) 6} = 14.1, MF _21i6 / / MF. _{2) I6} = 42.1.

Example 9 g of SiO 2 - Al 2 O 3 of the same type as in Example 1, dried overnight in an oven at 200 ° C, was treated with an ether solution of chlorobutyl-Grignard reagent (10 ml, 1/1 solution) in 10 ml hexane. The solvent was then evaporated in a rotary evaporator and added

1.2 g of V (CO) 4 Cp in 100 ml of hexane. After removal of the solvent in the evaporator, the dry product was refluxed in boiling TlCl4 for 6 hours, then filtered, washed and dried, the violet solid having the following composition:

Ti 9,20%

V 0,74%

Mg 1,07%

Cl 21.85%

212 mg of the product used in a standard polymerization under a pressure of 0.85 MPa of ethylene and 1.5 bar of hydrogen gave 325 g of polyethylene having a _2i16 == MF 1014, MF and _{2, 6} = 45.44, MF _{2 l) T} / MF ₂ , ₁₆ = 45.44, [η] = 2.0 dl / g and containing 65 ppm TI ++ V, with a Ti content of 61 ppm.

Claims (3)

SUBJECT A process for producing a catalyst component for the polymerization of α-olefins formed by the reaction product of a transition metal chloride and a titanium tetrachloride of the formula MCl _n . n TiCb where M is vanadium, manganese, cobalt or iron and n is a number equal to the valence M applied to a material with a large specific surface area, characterized in that BACKGROUND OF THE INVENTION The solvent is impregnated with a solvent to impregnate the transition metal compound at the lowest valence stage, heating the mixture to reflux in titanium tetrachloride, then removing the excess titanium tetrachloride. 2. The process according to claim 1, wherein the transition metal derivatives are used as such or in the form of a complex in the zero valence stage. 3. The process of claim 2 wherein the transition metal compound at the zero valence stage is selected from carbonyl derivatives.