Olefin polymerization with supported metallocene catalysts: Kinetic and modeling investigations

The current research project focuses predominantly on microscale studies—reaction kinetics and to a lesser extent, on mesoscale studies—polymer particle growth issues associated with olefin polymerization. Microscale studies deal with the investigation of three important kinetic variables—reactor, catalyst and comonomer. In the first part of this study, the effects of operational parameters such as temperature and comonomer concentration on the kinetics of homopolymerization and copolymerization with an unbridged metallocene are investigated. Online pressure and temperature perturbation techniques are implemented to determine important kinetic parameters. Comparisons are made between the kinetic behavior of ethylene-propylene and ethylene-1-hexene copolymerization. To quantify the effects of the kinetic parameters, a one-site kinetic model for homopolymerization and two-site model for copolymerization are proposed. In the second part of the study, the kinetics of ethylene-1-hexene polymerization with a bridged catalyst is investigated with parameters (obtained from perturbation techniques) and kinetics being compared to those of the unbridged catalyst. In the third part of this study, ethylene homopolymerization is conducted in the slurry reactor. The parameters obtained from the gas phase reactor are used in the slurry model to predict the kinetic behavior under various reaction conditions. The focus of the mesoscale studies is on particle stability and modifications to the existing particle growth model. In gas phase polymerization, ineffective heat transfer across the boundary layer of the polymer particle can cause severe melting problems. The objective of the current experimental effort is directed towards studying the effect of the presence of inerts in alleviating this melting problem. In the second project, the inclusion of sorptive and convective effects on the predictions of the current multigrain model (MGM) are studied. The case under investigation is ethylene/1-hexene copolymerization in the gas phase.