PROCESS FOR PREPARING A CO-CATALYST FOR USE IN THE POLYMERIZATION OF A-OLEFINS,A CO-CATALYST PREPARED BY THE PROCESS,A CATALYTIC SYSTEM COMPRISING SUCH A CO-CATALYST AND A PROCESS FOR POLYMERIZING AN A-OLEFIN USING SUCH CATALYTIC SYSTEM

摘要

For the preparation of the trichlorides of titanium and vanadium, a metal is vaporised in vacuo and the vapour thus obtained is reacted at low temperature with MCl4, M being Ti or V. The vaporisation of the metal takes place in a vacuum of between 10-1 and 10-6 mm Hg, and the reaction of the metallic vapours and MCl4 takes place at temperatures of between -80 and +20 DEG C in the presence of an inert diluent selected from saturated or unsaturated aliphatic hydrocarbons or from halogenated hydrocarbons. The metal to be vaporised is preferably selected from the group comprising Al, Mg, Cr, Mn, Fe, V and Ti. The trichlorides thus obtained and an organometallic aluminium compound are used in catalytic compositions for the polymerisation of alpha-olefins in high yield.