Unilever Patent Holdings B.v.

Pq Silicas UK Limited

Christine Elizabeth Marsden

Robert Joseph Parker

A method for preparing a catalyst precursor for an olefin polymerization catalyst involves the use of aqueous or alcoholic solutions of a chromium salt and of boric acid and aluminum carboxylate for deposition onto an inorganic support material, such as a silica xerogel. The chromium salt, aluminum carboxylate and boric acid are sufficiently soluble for deposition from a single solution to be effective. The catalyst precursor can be activated by calcination to form a catalyst for homo- or co-polymerisation of &#x3b1;-olefins which has productivity and melt flow index for the resulting polymer or copolymer which is comparable to results obtained with catalysts prepared by prior art organometallic routes. The activation of the catalyst precursor gives reduced levels of toxic or noxious fumes during activation compared to use of organometallic sources of chromium or aluminum.

Catalyst precursor particles, their preparation and use

Microspherical cogel particles comprising silica and at least one other metal oxide are prepared by forming a slurry of porous particulate material comprising silica and a liquid medium comprising at least 90%, by weight of the liquid medium, of an organic liquid and subjecting the slurry to spray drying. The method enables agglomeration of particulate material of especially small particle size to obtain microspherical particles of a size especially suitable for us as a catalyst support. The particles have a pore size of at least 2 cc/g and, especially when the particles contain titanium atoms, are especially suitable for use in the preparation of a catalyst for the polymerization of olefins.

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Chester, United Kingdom

Christine Elizabeth Marsden