PROCESS FOR PREPARING A VANADIUM-BASED CATALYST SUITABLE FOR OLEFIN POLYMERISATION

摘要

The present invention relates to a proces for preparing a Ziegler-Natta type catalyst based on a vanadium compound precipitated on a MgCl2 spherical support. The catalyst preparation consists of contacting within a liquid hydrocarbon a vanadium-reducing agent chosen from organometallic compounds with a vanadium compound soluble in the liquid hydrocarbon containing at least one halogen and one alkoxy group, and with a support containing (i) MgCl2 free from Mg-C bond and (ii) an organic electron donor compound free from labile hydrogen. The support consists of spherical particles having a well-defined diameter and a narrow particle size distribution. The catalyst is particularly suitable for manufacturing in a gas phase process elastomeric copolymers of propylene.