PARTICLE-SIZE DISTRIBUTION IN OLEFIN CONTINUOUS STIRRED-BED POLYMERIZATION REACTORS

The control of polymer particle size and PSD is of industrial importan ce. Very fine particles pack poorly, thereby limiting reactor capacity , and present a dust explosion hazard. In olefin polymerization, a par ticle size distribution (PSD) in the polymerization reactor has been d erived using population balances. Three reasonable reaction mechanisms for Ziegler-Natta catalysts, i.e., a simple reaction model, an active site reduction model, and a two sites model, have been used to derive the average number of active sites. It was observed that the PSD depe nds not only on residence time, but also on the reaction mechanism. It was also found that multiple active sites change the PSD slightly. Th e PSD, however, does not depend on initial catalyst volume.