(557c) Polyolefins: From Reactors to Catalyst Sites

Olefin polymerization is one of the most prominent polymerization processes characterized by its heterogeneous nature of catalytic reactions and various types of continuous polymerization reactors. On a reactor scale, polyolefin reactors exhibit strong nonlinear dynamics due to high exothermicity of the reaction and complex heat removal from both catalyst/polymer particle and reactor scales. The catalytic polymerization, represented by Zieger-Natta and metallocene catalysis, inevitably involve both intraparticle and interfacial mass and heat transfer limitations that affect the polymer yield and resulting polymer molecular weight distribution as well as composition distribution. Optimal grade transition and online model-based polymer properties estimation are also two practically important engineering problems that influence the process economy. In gas phase polymerization of ethylene, which is the dominant industrial process, the formation of fines has been the outstanding problems for years. In this talk, it will be illustrated that the root cause of such fine formation phenomena in gas phase polymerization is primarily due to unfavorable spatial distribution of catalyst components and subsequent premature and uncontrolled particle fragmentation.