Heterogeneity in the Fragmentation of Ziegler Catalyst Particles during Ethylene Polymerization Quantified by X-ray Nanotomography
Koen W. Bossers, Roozbeh Valadian, Jan Garrevoet, Stijn Van Malderen, Robert Chan, Nic Friederichs, John R. Severn, Arnold Wilbers, Silvia Zanoni, Maarten K. Jongkind, Bert M. Weckhuysen, Florian Meirer
Abstract
-means clustering algorithm that relates the quantity of polyethylene formed to the average size of the spatially resolved catalyst fragments. With this classification method, we have identified particles that exhibit weak, moderate, and strong degrees of catalyst fragmentation, showing that there is a strong heterogeneity in the overall catalyst particle fragmentation and thus polymerization activity within the entire ensemble. This hints toward local mass transfer limitations or other deactivation phenomena. The methodology used here can be applied to all polyolefin catalysts, including metallocene and the Phillips catalysts to gain statistically relevant fundamental insights in the fragmentation behavior of an ensemble of catalyst particles.