IMPROVED PROCESS FOR GAS-PHASE POLYMERIZATION HAVING HIGH POLYMER BED BULK DENSITY

摘要

The present invention relates to an improvement for gas-phase olefin polymerization process having relatively high bed bulk density. The improvement involves the use of mixed external electron donors when polymerizing propylene in a gas-phase reactor having a polymer bed with a bulk density greater than 128 kg/m3, optionally with one or more comonomers, wherein the mixed electron donor system comprises at least a first external electron donor and a second external electron donor, and wherein the first external electron donor is a carboxylate compound.