Patent ID: 6204346
Filing Date: 2001-03-20
Classification: C08F

Abstract:
A polymerization process comprising contacting under slurry polymerization conditions at a temperature within a range of about 200.degree. F. to about 226.degree. F. (about 93.degree. C. to about 108.degree. C.) in an isobutane diluent:a) ethylene monomer;b) at least 1 mono-1-olefin comonomer having about three to eight carbon atoms per molecule;c) a catalyst system comprising chromium supported on a silica-titania support, wherein said support comprises from about 1 to about 10 weight percent titanium, based on the weight on the support, wherein said catalyst system is aged twice and wherein the first aging is at a substantially neutral pH and wherein the second aging is at an alkaline pH, said catalyst system has a pore volume within a range of about 0.5 to about 1.3 ml/g, a surface area within a range about 150 to 400 m.sup.2 /g, and said catalyst system has been calcined at a temperature within a range of about 800.degree. F. to about 1300.degree. F. (about 427.degree. C. to about 704.degree. C.);d) about 1 to about 6 mg/kg, based on total reactor contents, of a trialkylboron compound; ande) recovering an ethylene/mono-1-olefin copolymer.