Probing the Morphology, Composition and Temperature of Olefin Polymerization Catalyst Particles with Microscopy and Spectroscopy

Abstract

The economic importance of polyolefins is undeniable with the annual production of polyethylene, polypropylene and related materials currently falling in the range of 100 Mt. Ever since supported transition metal-based catalysts were first used in the early 1950s to produce polyethylene under favorable process conditions, extensive research has been conducted to obtain a better structural and mechanistic understanding of these catalyst systems. Despite the undertaken efforts, several fundamental scientific questions, concerning the influence of the reaction conditions, heat and mass transfer, as well as the localized build-up of pressure on the activities and morphologies of supported olefin polymerization catalysts, remain. This PhD thesis describes how an analytical toolbox, consisting of various microscopy and spectroscopy techniques, was used to study the structure, composition and temperature of industrial-grade silica-supported ethylene polymerization catalysts, such as supported metallocene-based and Ziegler-Natta catalyst materials. Both families of heterogeneous catalysts were characterized in the early stages of active site genesis and polymer formation to elucidate structure-activity-morphology correlations at the single particle level. The acquired insights can ultimately contribute to the optimization of established catalyst systems, thereby improving both the catalyst productivity and the product quality. With the recycling of polymers gaining momentum, the potential of the previously mentioned toolbox for the characterization of heterogeneous catalysts in the field of chemical polyolefin recycling is also discussed.