Titanated chromium/silica-aluminophosphate catalyst
AssigneeFina Research, S.A.
InventorGuy L. Debras
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Abstract
The present invention relates to a chromium/silca-aluminophosphate catalyst, titanated under specific conditions and used for the homopolymerisation or the copolymerisation of ethylene. The polyethylene obtained with this catalyst has a high melt potential and a high shear resistance. The catalyst has a high level of activity.
Claims20
A process for preparing a supported chromium/silica-aluminophosphate 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) impregnating a silica support with aluminium phosphate;
- b) either simultaneously with or after step a) coating the support with chromium to form a chromium/silica-aluminophosphate catalyst;
- c) dehydrating the chromium/silica-aluminophosphate catalyst to remove physically, adsorbed water by heating the catalyst in an atmosphere of dry, inert gas;
- d) titanating the chromium/silica-aluminophosphate catalyst, to form a titanated chromium/silica-aluminophosphate catalyst having a titanium content of from 1 to 5% by weight Ti, based on the weight of the titanated catalyst;
- and
- e) activating the titanated catalyst at a temperature of from 500 to 900° C.
A chromium/silica-aluminophosphate 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, the catalyst comprising a silica aluminophosphate support, a chromium compound deposited on the support, and a titanium compound deposited on the support and comprising from 1 to 5% by weight Ti, based on the weight of the titanated catalyst.
A process for preparing polyethylene in the presence of a chromium/silica-aluminophosphate 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, the catalyst comprising a silica aluminophosphate support, a chromium compound deposited on the support, and a titanium compound deposited on the support and comprising from 1 to 5% by weight Ti, based on the weight of the titanated catalyst.
Dependencies are inferred from the claim text.