Modeling and analysis of a slurry reactor system for heterogeneous olefin polymerization: The effects of hydrogen concentration and initial catalyst size

This article deals with the development of a model for the polymerization p rocess using a Ziegler-Natta catalyst in a slurry reactor system. Employed here is the hierarchical model describing the entire reactor system that is subcategoried by the gas bubble phase, the continuous gas phase, the liqui d phase, the solid polymer particle, and the surface of catalyst where chem ical reaction occurs. The concept of the multigrain model (MGM) is introduc ed to describe the growth of polymer particle from the original catalyst pa rticle. We also adopt the concept of multiple active sites to elucidate the broad molecular weight distribution (MWD). The major concern here is the e ffects of the hydrogen concentration and the size of the initial catalyst o n the performance of the polymerization reactor. It is demonstrated that th e hydrogen gas can be used for the purpose of controlling not only the mole cular weight but the molecular weight distribution (MWD) of the polymer. In addition, the relationship between the molecular weight and the concentrat ion of hydrogen gas is investigated. The size of the initial catalyst is fo und to exercise a significant influence on the morphology of the resultant polymer particle. (C) 2001 John Wiley & Sons, Inc.