Heterogeneous catalyzed gas phase polymerization of olefins: Kinetic studies and modelling investigations

Developments in the polyolefin industry have resulted from advances in catalyst synthesis and reactor design. A key requirement for the synthesis of successful commercial products is the study of the underlying kinetic mechanisms. Insights obtained from such investigations facilitate the development of kinetic models that can serve as the fundamental bases for reactor design and operation.;In this work, a novel lab-scale stirred bed gas phase reactor equipped with an on-line gas composition control system is designed and constructed. This reactor is employed to study the kinetic behaviour of olefin copolymerization reactions using heterogeneous catalysts. In so doing, systematic kinetic studies are carried out using supported high activity catalysts of commercial importance. Through experiments including both ethylene and propylene homopolymerizations as well as ethylene/;Besides extracting kinetic information, a variety of analytical techniques are employed to study the polymer properties as well as mass transfer effects. Evidence is provided to support the existence of polymer partial melting at relatively high reaction temperatures. To further investigate and quantify the kinetic and diffusion effects in these catalyzed reactions, a novel temperature-perturbation technique is developed. A physical model of the particle growth mechanism as well as its mathematical representation is also presented and the diffusion limitations occurring in the system at high temperature are characterized and quantitatively analyzed. Furthermore, the practical implications of the results of this study on the operation of industrial scale polyolefin reactors are examined.;Finally, a generalized kinetic model for catalyzed olefin copolymerization is extended to include long chain branching through internal/pendant double bond mechanism. Using the method of moments, polymer properties including long chain branching parameters are calculated. Simulations of systems of industrial interest are presented to prove the fidelity of the model.