Catalyst impregnated on fine silica, process for preparing, and use for ethylene polymerization

Claim 1

In a process for producing ethylene copolymer containing ≧90 mol percent of ethylene and ≦10 mol percent of one or more C 3 to C 8 alpha olefins wherein said copolymer is produced in granular form at a density of ≧0.91 to ≦0.94 with a Ti containing catalyst at a productivity level of ≧5 ppm of titanium per million parts of copolymer by a process which comprises copolymerizing ethylene with at least one C 3 to C 8 alpha olefin in a reactor at a temperature of about 30° to 105° C. under a pressure of up to about 1000 psi in the gas phase by contacting the monomer charge with, in the presence of about 0 to 2.0 mols of hydrogen per mol of ethylene in the gas phase reaction zone, particles of a catalyst composition comprising a precursor composition of the formula Mg.sub.m Ti.sub.1 (OR).sub.n X.sub.p [ED].sub.q wherein R is a C 1 to C 14 aliphatic or aromatic hydrocarbon radical, or COR' wherein R' is a C 1 to C 14 aliphatic or aromatic hydrocarbon radical, X is selected from the group consisting of Cl, Br, I or mixtures thereof, ED is an electron donor compound, m is ≧0.5 to ≦56, n is 0, 1 or 2, p is ≧2 to ≦116, and q is ≧2 to ≦85, said precursor composition being impregnated in a porous support in a weight ratio of 0.1:1 to 0.33:1 and being first partially activated outside of said reactor with >0 to <10 mols of activator compound per mol of Ti in said precursor composition, and then completely activated in said reactor with ≧10 to ≦400 mols of activator compound per mol of Ti in said precursor composition, said activator compound having the formula Al(R").sub.c X'.sub.d H.sub.e wherein X' is Cl or OR"', R" and R"' are the same or different and are C 1 to C 14 saturated hydrocarbon radicals, d is 1 to 1.5, e is 1 or 0 and c+d+e=3, said electron donor compound being a liquid organic compound in which said precursor composition is soluble and which is selected from the group consisting of alkyl esters of aliphatic and aromatic carboxylic acids, aliphatic ethers, cyclic ethers and aliphatic ketones, the improvement which comprises employing as said support throughout the polymerization silica having a particle size distribution within the range of from 2 microns to 80 microns and an average particle size of from 20 microns to 50 microns.