Spheroidal polymerization catalyst, process for preparing, and use for ethylene polymerization

A catalyst composition produced by

• (A) forming a spherical precursor composition of the formula:
• Mg.sub.m Ti.sub.1 (OR).sub.n X.sub.p [ED].sub.q [Filler].sub.r
• wherein R is a C.sub.1 to C.sub.14 aliphatic or aromatic hydrocarbon radical, or COR' wherein R' is a C.sub.1 to C.sub.14 aliphatic or aromatic hydrocarbon radical, X is Cl, Br, I, or mixtures thereof, ED is an electron donor compound, Filler is an inert filler compound, and, based on the total weight of said composition,
• m is .gtoreq.0.5 to .ltoreq.56,
• n is 0 or 1,
• p is .gtoreq.2 to .ltoreq.116,
• q is .gtoreq.2 to .ltoreq.85, and
• r has a value such that the percent filler is from about 10 to about 95 weight percent based on the total weight of said composition,
• by forming a slurry or solution of at least one magnesium compound and at least one titanium compound and at least one filler compound in at least one electron donor compound so as to thereby form a slurry or solution of said precursor composition in said electron donor compound and spray drying said slurry or solution by atomization to form spherical particles of said precursor composition which have a particle size of from about 10 to about 200 microns,
• said magnesium compound having the structure MgX.sub.2,
• said titanium compound having the structure Ti(OR).sub.a X.sub.b
• wherein a is 0, 1 or 2, b is 1 to 4 inclusive and a+b=3 or 4,
• said electron donor compound being a liquid organic compound in which said magnesium compound and said titanium compound are 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, and
• (B) activating said precursor composition
• either by partially activating it with >0 to .ltoreq.10 moles of activator compound per mol of Ti in said precursor composition, or
• completely activating it with 10 to 500 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.sub.1 to C.sub.14 saturated hydrocarbon radicals, d is 0 to 1.5, e is 1 or 0 and c+d+e=3,
• said activating being conducted after the recovery of said particles of said precursor composition by treating the precursor composition with said activator compound.