Bp Chemicals Limited

Claude Chamla

Erick Dominique Daire

John Gabriel Speakman

The present invention relates to a catalyst and a process for preparing a catalyst suitable for polymerization of olefins. The process is carried out in a hydrocarbon liquid medium and comprises successively contacting a refractory oxide support with (a) a dialkylmagnesium optionally with a trialkylaluminium, (b) a particular monochloro organic compound, (c) a titanium and/or vanadium compound(s), and then (d) with ethylene optionally mixed with a C.sub.3 -C.sub.8 alpha-olefin in the presence of an organo-aluminium or organozinc compound to form a prepolymerised catalyst. The catalyst has a high activity, particularly in a gas phase polymerization of ethylene, and has a great ability of copolymerizing alpha-olefins with ethylene.

Supported polyolefin catalyst for the (co-)polymerization of ethylene in

The present invention relates to a catalyst and a process for preparing a catalyst suitable for polymerization of olefins. The process is carried out in a hydrocarbon liquid medium and comprises successively contacting a refractory oxide support with (a) a dialkylmagnesium optionally with a trialkylaluminium, (b) a particular monochloro organic compound, (c) a titanium and/or vanadium compound(s), and then (d) with ethylene optionally mixed with a C.sub.3 -C.sub.8 alpha-olefin in the presence of an organo-aluminium or organozinc compound to form a prepolymerized catalyst. The catalyst has a high activity, particularly in a gas phase polymerization of ethylene, and has a great ability of copolymerizing alpha-olefins with ethylene.

Supported polyolefin catalyst for the (Co-)polymerization of ethylene in

Process for polymerising ethylene, or copolymerising ethylene with an alpha-olefin, in the gas phase in the presence of a prepolymer/catalyst composition, the catalyst being an activated chromium oxide supported on a refractory oxide. The prepolymer is treated to an extraction with a solution comprising inert hydrocarbon and an organometallic compound, for example an alkylaluminum, prior to being dried and introduced into the gas phase (co) polymerisation. Prepolymer thus treated has improved properties in the dry state, for example improved flow.

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Marignane, France

Claude Chamla