Ethylene Polymerization Kinetics and Microstructure of Polyethylenes Made with Supported Metallocene Catalysts

The microstructure of polyolefins made with a metallocene supported on a porous carrier is generally less homogeneous than when the polyolefin is made with the same unsupported metallocene. For instance, the molecular weight and chemical composition distributions of ethylene/1-olefin copolymers are often broader when they are made with a supported metallocene. In this article, a mathematical model is used to quantify this phenomenon. The polymerization of ethylene was investigated in parallel semi-batch reactors using a metallocene catalyst supported on an inorganic porous carrier. Ethylene pressure, polymerization temperature, and H 2 concentration were the factors changed to study ethylene polymerization kinetics with this catalyst system. Modeling results showed that a three-site model was needed to describe the molecular weight distributions of the polyethylene samples made with this catalyst.