Process for preparing high density or medium density polymers

Claim 1

A process for polymerizing at least one olefin comprising conducting the polymerization in the presence of a catalyst composition prepared by a method comprising the steps of: (I) preparing a catalyst precursor by a method comprising: (a) contacting a solid, porous carrier with an aluminum compound of the formula R.sub.k AlZ.sub.(3-k) (I) where R is a C 1 -C 10 alkyl group, Z is a halogen and k is 1,2, or 3; (b) contacting the product of step (a) with a mixture containing a vanadium compound of the formula VO.sub.m X.sub.(n-2m) (II) where X is a halogen, m is 0 or 1 and n is 2,3,4 or 5, and a titanium compound of the formula TiX'.sub.4 (III) where X' is a halogen; (c) contacting the product of step (b) with an ether selected from the group consisting of an alkyl ether having 2 to 18 carbon atoms, an alkyl/aryl ether having 2 to 18 carbon atoms, or a silane ether of the formula R"Si(OR'").sub.m R.sup.IV.sub.(3-m) (IV) where R", R'" and R IV are the same or different alkyl or aryl groups and m is 1,2,or 3; and (II) activating the precursor by combining it with an olefin polymerization catalyst activator.