A catalyst formed from selected organo aluminum compounds and a precursor composition of the formulaMg.sub.m Ti.sub.l (OR).sub.n X.sub.p [ED].sub.qwhereinED is a selected electron donor compoundm is .gtoreq.0.5 to .ltoreq.56n is 0 or 1p is .gtoreq.6 to .ltoreq.116q is .gtoreq.2 to .ltoreq.85R 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, andX is selected from the group consisting of Cl, Br, I, or mixtures thereof, which catalyst is in particulate form and diluted with an inert carrier material; a process for preparing such catalyst; a process for using said catalyst to readily prepare ethylene homopolymer having a density of about .gtoreq.0.958 to .ltoreq.0.972 and a melt flow ratio of .gtoreq.22 to .ltoreq.32 in a low pressure gas phase process at a productivity of .gtoreq.50,000 pounds of polymer per pound of Ti. Novel polymers and molded articles are prepared.