Total Petrochemicals Research Feluy

Fina Research, S.a.

Nicodeme Lonfils

Guy L Debras

Philippe J Bodart

The present invention concerns a catalyst for the production of high density polyethylene, by homopolymerising ethylene or copolymerising ethylene and an alpha-olefinic comonomer comprising 3 to 10 carbon atoms, prepared by the steps of:

Multimodal polyethylene obtained with multilayer chromium catalyst

The present invention concerns a catalyst for the production of high density polyethylene, by homopolymerising ethylene or copolymerising ethylene and an alpha-olefinic comonomer comprising 3 to 10 carbon atoms, prepared by the steps of: a) selecting a silica support with a specific surface area larger than 300 m2/g; b) treating the silica support with a titanium compound, in order to introduce titanium into the support, or with an aluminium compound, in order to introduce aluminium into the support; c) either treating the titanated silica support with an aluminum compound, in order to introduce aluminum into the titanated silica support, or treating the aluminated silica support with a titanium compound, in order to introduce titanium into the aluminated silica support; d) depositing a chromium compound on the titanated and aluminated silica support to form a catalyst; e) activating the catalyst of step d) under air in a fluidised bed at a temperature of from 600 to 800&#xb0; C.

A process for producing a chromium-based catalyst for the production of polyethylene, the process comprising the steps of providing a catalyst support selected from silica, silica-titania and silica-zirconia; reacting the support with one of an aluminium alkyl compound or a chromium salt compound selected from at least one of chromium (III) acetylacetonate, chromium (III) acetate, chromium (III) oxalate and chromium (III) stearate; and thereafter reacting the support with the other of the aluminium alkyl compound or the chromium salt to produce a chromium-impregnated catalyst having a silica-alumina support, the catalyst composition comprising from 0.4 to 1.5 wt % chromium, based on the weight of the chromium-based catalyst and the alumina in the silica-containing support comprising from 0.5 to 4 wt % aluminium in the chromium-based catalyst.

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Brussels, Belgium

Nicodeme Lonfils