POLYMERIZATION OF OLEFINS THROUGH HETEROGENEOUS CATALYSIS .11. GAS-PHASE SEQUENTIAL POLYMERIZATION KINETICS

A unique series of ethylene and propylene sequential polymerization experiments have been carried out in a stirred bed gas phase reactor using unsupported Stauffer AA catalyst (TiCl3 . 1/3 AlCl3). Several interesting kinetic results were observed. It was found that propylene causes rate enhancement for a subsequent ethylene polymerization but that ethylene causes a rate reduction for a subsequent propylene polymerization. Furthermore, the rate enhancement/reduction effect increases with the duration of the preceding polymerization. Chemical/kinetic effects were found to be the likely causes of both the rate enhancements and the rate reductions observed during sequential polymerization. It was also shown that enhanced monomer sorption caused by the presence of a more soluble component, such as a heavier comonomer, does contribute to rate enhancement during simultaneous copolymerizations, but is not a factor for sequential polymerizations. (C) 1993 John Wiley & Sons, Inc.