Chemical modification of silica support to improve the branching ability of Phillips catalyst
A variety of modified Phillips catalysts were synthesized by employing three kinds of chemical modifiers for silica support: (1) organic modification with silane coupling agents, (2) Lewis acidic modification with typical metal alkyl or alkoxide, and (3) modification with transition-metal alkoxide. The activity and branching ability of these catalysts were investigated for ethylene polymerization. It was revealed that the chemical modification of silica support was a good methodology for controlling the catalyst activity as well as the branching level in resultant polyethylene.