PROCESS FOR STARTING POLYMERIZATION OF ETHYLENE OR COPOLYMERIZATION OF ETHYLENE AND ALPHA-OLEFIN IN THE GAS PHASE IN THE PRESENCE OF A CHROMIUM OXIDE CATALYST

摘要

P THE PRESENT INVENTION CONCERNS A PROCESS FOR STARTING POLYMERIZATION OF ETHYLENE OR OF COPOLYMERIZATION OF ETHYLENE AND AT LEAST ONE OTHER ALPHA-OLEFIN BY CONTACT, IN CONDITIONS OF POLYMERIZATION OR OF COOLUTED AND STITCHED BED MECHANICALLY, ETHYLENE AND POSSIBLY AT LEAST ONE OTHER ALPHA-OLEFIN WITH A POWDER LOAD, IN THE PRESENCE OF A CATALYST COMPRISING A COMPOUND OF CHROMIUM OXIDE ASSOCIATED WITH A GRANULAR SUPPORT AND ACTIVE THERMAL TREATMENT, THIS CATALYST BEING IMPLEMENTED IN THE FORM OF PREPOLYMER, PROCESS CHARACTERIZED IN THAT THE CHARGING POWDER USED IS PREVIOUSLY SUBJECT TO A TREATMENT BY CONTACT OF SAID CHARGING POWDER WITH AN ORGANOALUMINIC COMPOUND, SUCH AS POLYMERIZATION OR COPOLYMERIZATION CONTACT OF ETHYLENE AND POSSIBLY AT LEAST ONE OTHER ALPHA-OLEFIN WITH PREPOLYMER POWDER IN THE PRESENCE OF PREPOLYMER. /P