Abstract
A combination of X-ray ptychography and X-ray fluorescence tomography (XRF) has been used to study the fragmentation behavior of an individual Ziegler-Natta catalyst particle, ∼40 μm in diameter, in the early stages of propylene polymerization with submicron spatial resolution. The electron density signal obtained from X-ray ptychography gives the composite phases of the Ziegler-Natta catalyst particle fragments and isotactic polypropylene, while 3-D XRF visualizes multiple isolated clusters, rich in Ti, of several microns in size. The radial distribution of Ti species throughout the polymer-catalyst composite particle shows that the continuous bisection fragmentation model is the main contributor to the fragmentation pathway of the catalyst particle as a whole. Furthermore, within the largest Ti clusters the fragmentation pathway was found to occur through both the continuous bisection and layer-by-layer models. The fragmentation behavior of polyolefin catalysts was for the first time visualized in 3-D by directly imaging and correlating the distribution of the Ti species to the polymer-catalyst composite phase.
| Original language | English |
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| Pages (from-to) | 3691-3695 |
| Number of pages | 5 |
| Journal | Journal of the American Chemical Society |
| Volume | 142 |
| Issue number | 8 |
| DOIs | |
| Publication status | Published - 26 Feb 2020 |
Funding
We acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Parts of this research were carried out at PETRA III. We would like to thank Dennis Brückner (Universität Hamburg), Dr. Matthias Alfeld (TU Delft), and Max Werny (Utrecht University, UU) for assistance in using the P06 microprobe beamline; Robert Chan (SABIC) for performing SEM measurements; and Dr. Martin Veselý (UU, UCT Prague) and Dr. John Severn (DSM Materials Science Center) for helpful discussions. This research was supported in part through the Maxwell computational resources operated at Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany. This work was funded by The Netherlands Organization for Scientific Research (NWO) in the frame of a NWO-TA grant (No. 731.015.203) with SABIC, DSM Resolve, and the University of Maastricht and a VIDI grant (No. 723.015.007).