| 摘要 |
A process for preparing a supported chromium-based catalyst for the production of high density polyethylene, by polymerising ethylene, or copolymerising ethylene and an alpha-olefinic comonomer comprising 3 to 10 carbon atoms, which comprises the steps of: a) providing an alumina-containing support; 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° C. in an atmosphere of dry, inert gas; d) titanating the chromium-based catalyst at a temperature of at least 300° C. in an atmosphere of dry, inert gas containing a titanium compound of the general formula selected from RnTi(OR')m and (RO)nTi(OR')m wherein R and R' are the same or different and are hydrocarbyl groups 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; and e) activating the titanated catalyst at a temperature of from 500 to 900° C.
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