PROCATALYST, PROCATALYST PRECURSOR, AND PROCESS FOR THE PREPARATION OF A MULTIMODAL ETHYLENE POLYMER

摘要

A procatalyst, a procatalyst precursor and a process for the preparation thereof are described. A process for the preparation of a multimodal, preferably bimodal ethylene homopolymer or copolymer by gas-phase polymerisation, preferably in two steps is also described. The procatalyst used in the process is prepared by: a) contacting the support, preferably silica with a halogenating agent, preferably ethyl aluminium dichloride to obtain a first reaction product; b) contacting the first reaction product with a compound or mixture containing hydrocarbyl and one or more of hydrocarbyloxy, monoalkylamido, dialkylamido, carboxylato and alkoxymethoxy groups linked to magnesium, thereby to obtain a second reaction product (the procatalyst precursor); and c) contacting the second reaction product with a titanium compound, preferably TiCl4.