Patent ID: 6200920
Filing Date: 2001-03-13
Classification: C08F,Y02P

Abstract:
A process for preparing a supported chromium-based catalyst for the production of high density polyethylene, by polymerizing ethylene, or copolymerizing ethylene and an alpha-olefinic comonomer comprising 3 to 10 carbon atoms, which comprises the steps of:a) providing a support consisting essentially of silica having a specific surface area of at least 400 m.sup.2 /g;b) depositing a chromium compound on the support to form a chromium-based catalyst;c) dehydrating the chromium-based catalyst to remove physically adsorbed water by heating the catalyst at a temperature of at least 300.degree. C. in an atmosphere of dry, inert gas;d) titanating the chromium-based catalyst at temperature of at least 300.degree. C. in an atmosphere of dry, inert gas containing a titanium compound of the general formula selected from R.sub.n Ti(OR').sub.m and (RO).sub.n Ti(OR').sub.m wherein R and R' are the same or different and are a hydrocarbyl group containing from 1 to 12 carbon atoms, n is 0 to 3, m is 1 to 4 and m+n equals 4, to form a titanated chromium-based catalyst having a titanium content of from 1 to 5% by weight, based on the weight of the titanated catalyst ande) activating the titanated catalyst at a temperature of from 500 to 900.degree. C.