Kinetic study of olefin polymerization with a supported metallocene catalyst. I. Ethylene/propylene copolymerization in gas phase

A kinetic study of ethylene homopolymerization and copolymerization is cond ucted with a supported metallocene catalyst in a gas-phase reactor. An expe rimental procedure is developed that minimizes the effect of impurities in the reactor and simultaneously yields consistent and reproducible reaction- rate data. The effects of operational parameters such as reaction temperatu re, pressure, and comonomer concentration on the kinetics of both homopolym erization and copolymerization are investigated. Online perturbation techni ques are implemented to determine key kinetic parameters such as the activa tion energies for ethylene propagation and catalyst deactivation. A reactio n-rate order close to 2 is obtained for ethylene homopolymerization from pr essure perturbations, while near to first-order dependency is observed in t he presence of propylene. To quantify the effects of the operational, param eters, a one-site kinetic model for homopolymerization and a two-site kinet ic model for copolymerization are proposed. The necessary kinetic parameter s in the model are estimated using the POLYRED(TM) package. The resulting k inetic model represents the kinetic data over a wide range of conditions fo r this supported metallocene catalyst. (C) 2001 John Wiley & Sons, Inc.