A kinetic model for ethylene polymerization with a polymer supported Ziegler-Natta catalyst

A kinetic model including two types of active sites was developed for the p olymerization of ethylene in slurry with a polymer supported Ziegler-Natta catalyst to predict monomer conversion, polymerization rate and molecular w eights. The model includes activation of active sites, propagation, deactiv ation, chain transfer by hydrogen and the effect of monomer diffusion throu gh the polymer layer around the catalyst particles to the active sites. Tra nsformation of active sites from type I to type II is allowed. The polymeri zation data were obtained from a semibatch slurry reactor under constant te mperature and pressure. The experimental program was carried out according to a central composite design with monomer partial pressure, catalyst loadi ng, hydrogen to monomer ratio, temperature, and catalyst particle size as p rocess variables.