GB838028A - Polymerization catalyst - Google Patents

Abstract

Catalysts for polymerizing olefines are made by reacting a reducing organo-aluminium compound with a reducible compound of a Group IVa metal in the presence of a solid carrier material as support. Preferably the support is first impregnated with the heavy metal compound (e.g. TiCl4 or ZrCl4) and then with the reducing agent (e.g. aluminium alkyl compound). Supports of large surface area specified include alumina, silica, calcium/aluminium silicate, zirconia, zeolites, powdered synthetic resins, natural and synthetic fibres, e.g. wool, silk, or cellulose sponge; natural and synthetic rubber, colloidal metal oxides, or activated carbons. Reducing organo-aluminium compounds include trialkyl aluminium compounds, dialkyl aluminium halides, alkyl aluminium di-halides; but alkoxy or sulphur radicals may also be present. Compounds of mild reducing action may be used, e.g. trimethyl aluminium or higher alkyl derivatives of 10 C atoms or more may be used. Zirconium or titanium tetra-halides are the preferred reducible compounds, but oxy-halides, alcoholates, benzoates, or acetyl acetonates may be used. Preferably the catalyst/carrier composition is formed in the presence of a solvent, e.g. heptane. The supported catalyst may be applied to polymerize ethylene, butylene, hexadecene, butadiene, or styrene, and diluents may be present.ALSO:Olefines are polymerized with catalysts formed by reacting a reducing organo-aluminium compound with a reducible compound of a Group IVa metal in the presence of a support of large surface area. Preferably the support is first impregnated with the heavy metal compound, e.g. TiCl4, ZrCl4, and then with the aluminium reducing agent. Supports of large surface area include: alumina, silica, calcium/aluminium silicates, zeolite, zirconia, titanium oxide; synthetic resins, e.g. coumarone, ureaformaldehyde, vinyl, styrene, acrylic acid, polyethylene, all in powder form, natural or synthetic fibres, e.g. silk, wool, acetate, cellulose sponge; natural or synthetic rubbers, glass, carbon, or colloidal metal oxides. Zirconium or titanium tetrahalides are the preferred reducible metal compounds, but oxy-halides, benzoates, alcoholates, and acetonyl acetonates are also referred to. Reducing organo-aluminium compounds include: tri-alkyl aluminium halides, alkyl aluminium di-halides, but alkoxy, and organic sulphurs and N radicals may also be present. Compounds of mild reducing action, e.g. tri-methyl aluminium, and higher alkyl derivatives containing 10 C atoms or more, or the corresponding halides may be used. Preferably the catalyst/carrier composition is formed in the presence of a diluent to be used in the polymerizing process, e.g. heptane, tetra-hydronaphthalene, halogenated aromatic hydrocarbons, benzene, xylene or mixtures thereof. The catalyst in suspension is preferably aged before use and then applied to polymerize olefines including styrene, hexadecene, also butadiene or mixtures thereof. Polymers of molecular weight up to 3 million may be made; the catalyst may be left in if preferred.