On the Fragmentation Behavior of Ziegler-Type Catalysts During the Early Stages of α-Olefin Polymerization

Abstract

In this PhD Thesis the fragmentation behavior of Ziegler-type polyolefin catalysts was studied using advanced chemical imaging techniques. The fragmentation behavior plays a crucial part during the polymerization of a-olefins such as ethylene and propylene to ensure a well-controlled polymerization process, prevent reactor fouling and facilitate facile processing of the obtained polymer particles. For the first time, the fragmentation behavior of the highly moisture sensitive Ziegler-type catalyst particles was captured in 3-D over large field of views with high sub 100-nm spatial resolution using X-ray nanotomography. Additionally, a model system was developed to study the fragmentation behavior with surface sensitive techniques. This model system bridges the knowledge gap between planar thin films and industrially used spherical particles, through the use of spherical caps. These spherical caps therefore allow the research to mimic the shape of industrially relevant catalyst particles whilst being compatible with surface sensitive imaging techniques. The methodologies developed in this PhD Thesis to study the fragmentation behavior of Ziegler-type catalysts can be extended and applied to all other types of polyolefin catalysts such as the Phillips catalysts and immobilized metallocene catalysts.