THE REACTION KINETICS, MODELLING AND CONTROL OF SOLID CATALYZED GAS PHASE OLEFIN POLYMERIZATION REACTORS

The kinetics of gas phase olefin polymerization and two industrially important continuous gas phase polymerization reactors have been studied. Recent progress in polyolefin processes and catalysts has also been reviewed through an extensive literature survey.; To verify the complex kinetics of gas phase propylene polymerization, a pilot plant has been constructed and operated under various operating conditions using (delta)-TiCl(,3).0.33 AlCl(,3) /DEAC catalyst. The activation energy for the gas phase reaction was found to be much smaller than that for liquid slurry polymerization. Simulation results using the Multigrain Model indicate that the retardation of reaction rate at high temperatures occurs due to intraparticle monomer diffusion resistance. The effect of catalyst composition, reaction pressure and hydrogen addition on the polymerization rate and polymer properties has also been investigated.; The steady state and dynamic behavior of the continuous stirred bed reactor for gas phase propylene polymerization has been studied through detailed mathematical modelling and stability analysis. The reactor system, which utilizes liquefied monomer to remove the reaction heat, is characterized by the existence of a unique, open loop unstable steady state. Tight control of reactor temperature and pressure must be effected to avoid liquefaction of monomer and dangerous reactor runaway.; A two-phase model was applied to visualize the behavior of fluidized bed reactors for ethylene and propylene polymerization catalyzed by solid catalysts. It has been found that in both ethylene and propylene polymerization, multiple steady states, branching to oscillatory behavior and runaway phenomena may occur for some operating conditions. Simulation results also indicate that some difficulty may be encountered in controlling the reaction temperature due to the limited cooling capacity of the recirculating gas.