Abstract: A catalyst for producing polymers of ethylene in which a first composition prepared by reacting an inorganic support containing surface hydroxyl groups with titanium or vanadium compounds which also comprise halogen and/or OR groups wherein R is hydrocarbyl is further reacted to form a second composition by subsequent contact with a compound of titanium or vanadium as defined above chosen from compounds of the metal not reacted to form the first composition, producing a third composition by reaction of the second composition with an organoaluminum compound with the third composition being reacted with titanium tetrahalide to form the catalyst composite. A method for producing polymers of ethylene by contacting ethylene monomer in the presence of the catalyst composite described above and an organoaluminum compound under conditions suitable for polymerization.

Abstract: Aliphatic monoolefins are polymerized employing a catalyst consisting of a first component formed by co-comminuting a mixture of a halogenated titanium compound, a magnesium or manganese dihalide, a Lewis base, and an aromatic compound which is normally liquid at about 25.degree. C; a second component consisting of a trialkylaluminum compound and a Lewis base; and, optionally, third component which is a dialkylaluminum halide.