Preparation of homopolymers and copolymers of ethene by Phillips catalysis

A process for the preparation of ethene homopolymers and ethene copolymers containing minor amounts of copolymerized C.sub.3 -C.sub.12 -.alpha.-monoalkenes, by polymerization of the monomer or monomers at from 30.degree. to 150.degree. C., under pressure from 2 to 150, bar by Phillips catalysis using (1) a supported catalyst consisting of a carrier which is laden with oxidic chromium, oxidic phosphorus and oxidic titanium and (2) a cocatalyst, the supported catalyst (1) being obtained by a procedure in which

• (1.1) in a first stage, a catalyst intermediate (1.1) laden with the desired amounts of chromium, phosphorus and titanium is prepared from
• (1.1.a) a finely divided, porous silicate carrier,
• (1.1.b) a selected, specific chromium compound,
• (1.1.c) a selected, specific phosphorus compound and
• (1.1.d) a selected, specific titanium compound, and then
• (1.2) in a second stage, the catalyst intermediate (1.1) obtained from the first stage is kept in an anhydrous gas stream containing oxygen in a concentration of more than 10% by volume for from 10 to 1000 minutes at from 300.degree. to 900.degree. C., thus converted to the actual supported catalyst (1), wherein
• (1) a supported catalyst is used which is obtained by a procedure in which
• (1.1) in a first stage, a catalyst intermediate is produced by a method in which first
• (1.1.1) in a first substage, a suspension is prepared from
• (1.1.1.1) a finely divided, porous, silicate carrier which has a particle diameter of from 1 to 400 .mu.m, a pore volume of from 0.5 to 3 cm.sup.3 /g and a specific surface area of from 100 to 1000m.sup.2 /g and
• (1.1.1.2) an inert organic solvent, with thorough mixing, with the proviso that from 150 to 5000 parts by weight of the solvent (1.1.1.2) are used per 100 parts by weight of the carrier (1.1.1.1), then
• (1.1.2) in a second substage, a suspension is prepared from
• (1.1.2.1) a finely divided chromium trioxide (CrO.sub.3) having a particle diameter of less than 2000 .mu.m, and
• (1.1.2.2) a solvent of the type defined under (1.1.1.2), with thorough mixing, with the proviso that more than 1 part by weight of the solvent (1.1.2.2) are used per part by weight of the chromium trioxide (1.1.2.1), thereafter
• (1.1.3) in a third substage,
• (1.1.3.1) the suspension resulting from (1.1.2) is combined with
• (1.1.3.2) a phosphorus compound of the formula P(O)(OR).sub.3 or P(O)H(OR).sub.2, where R is an alkyl, aryl or cycloalkyl group of not more than 12 carbon atoms or hydrogen with the proviso that 1 or more radicals R must not be hydrogen, with further thorough mixing at from 0.degree. to 60.degree. C. with the proviso that from 0.6 to 10 parts by weight of phosphorus from the phosphorus compound (1.1.3.2) are present per part by weight of chromium from the chromium trioxide (1.1.2.1), and the entire mixture is kept for the stated temperature for from 5 to 300 minutes, thereafter
• (1.1.4) in a fourth substage,
• (1.1.4.1) the suspension resulting from (1.1.1) is combined with
• (1.1.4.2) the reaction product obtained in substage (1.1.3) with thorough mixing at from 0.degree. to 60.degree. C. with the proviso that from 0.1 to 5 parts by weight of chromium from the chromium trioxide (1.1.2.1) are present per 100 parts by weight of the carrier (1.1.1.1), and the entire mixture is kept at the stated temperature for from 5 to 300 minutes, then
• (1.1.5) in a fifth substage,
• (1.1.5.1) the suspension formed in substage (1.1.4) is combined with
• (1.1.5.2) a titanium compound of the formula Ti(OR.sup.1).sub.4, where R.sup.1 is an alkyl, aryl or cycloalkyl group of not more than 12 carbon atoms, with further thorough mixing at from 0.degree. to 60.degree. C. with the proviso that from 0.1 to 10 parts by weight of titanium from the titanium compound (1.1.5.2) are present per 100 parts by weight of the carrier (1.1.1.1), and the entire mixture is kept at the stated temperature for from 5 to 300 minutes, and finally
• (1.1.6) in a sixth substage, the suspension obtained in substage (1.1.5) is evaporated to dryness at not more than 150.degree. C. under atmospheric or reduced pressure, and then
• (1.2) in a second stage, the catalyst intermediate obtained in the first stage (1.1) is converted to the actual supported catalyst by a procedure in which first
• (1.2.1) in a first substage, the catalyst intermediate obtained in the first stage (1.1) is kept in an anhydrous stream of nitrogen for from 60 to 500 minutes at from 150.degree. to 300.degree. C., thereafter
• (1.2.2) in a second substage, the intermediate obtained in substage (1.2.1) is kept in an anhydrous gas stream containing oxygen in a concentration of more than 10% by volume for from 10 to 1000 minutes at from 300.degree. to 900.degree. C., and finally
• (1.2.3) in a third substage, the intermediate obtained in substage (1.2.2) is kept in an anhydrous stream of nitrogen for from 10 to 300 minutes at from 50.degree. to 400.degree. C., and
• (2) a lithiumalkyl of the formula LiR.sup.2, where R.sup.2 is C.sub.1 -C.sub.12 -alkyl is used as a cocatalyst, with the proviso that the atomic ratio of chromium in the supported catalyst (1) to lithium in the cocatalyst (2) is greater than 1:100.