Chapter 4 Synthesis, Chemical Composition, and Structure of Transition Metal Components and Cocatalysts in Catalyst Systems for Alkene Polymerization

Abstract

This chapter reviews diverse subjects: (1) synthesis techniques and compositions of supported Ziegler–Natta catalysts, (2) structures of transition metal compounds serving as precursors in homogeneous polymerization catalysts, (3) the chemistry of reactions between various transition metal catalysts and cocatalysts, and (4) basic information about catalyst activity. In the case of metallocene catalyst systems and many non-metallocene homogeneous catalysts, the second subject is straightforward; the structures of the initial complexes are known, mostly from X-ray and nuclear magnetic resonance (NMR) data. The chemistry of principal reactions between the soluble complexes of transition metals and organo-aluminum cocatalysts, including the reactions leading to the formation of active centers in homogeneous catalysts, is also well researched. On the other hand, nearly all commercial Ti-based Ziegler–Natta catalysts are complex multi-component mixtures. The chapter contains information on both components of these catalysts, Ti-containing catalysts and cocatalyst mixtures. The chapter discusses the preparation of several important types of commercial supported catalysts. These preparations describe procedures in which the solid components are prepared: chemical ingredients, the order of their interactions, the physical structure of final solid materials. The chapter also provides information about the performance of the catalysts. These general data usually include (1) catalyst productivity, (2) copolymerization ability of catalysts designed for ethylene copolymerization reactions, (3) fractional isospecificity of catalysts designed for propylene polymerization reactions, and (4) molecular weight distribution of polymers.