Visualizing the Structure, Composition and Activity of Single Catalyst Particles for Olefin Polymerization and Polyolefin Decomposition

The structural and morphological characterization of individual catalyst particles for olefin polymerization, as well as for the reverse process of polyolefin decomposition, can provide an improved understanding for how these catalyst materials operate under relevant reaction conditions. In this review, we discuss an emerging analytical toolbox of 2D and 3D chemical imaging techniques that is suitable for investigating the chemistry and reactivity of related catalyst systems. While synchrotron-based X-ray microscopy still provides unparalleled spatial resolutions in 2D and 3D, a number of laboratory-based techniques, most notably focused ion beam-scanning electron microscopy, confocal fluorescence microscopy, infrared photoinduced force microscopy and laboratory-based X-ray nano-computed tomography, have helped to significantly expand the arsenal of analytical tools available to scientists in heterogeneous catalysis and polymer science. In terms of future research, the review outlines the role and impact of in situ and operando (spectro-)microscopy experiments, involving sophisticated reactors as well as online reactant and product analysis, to obtain real-time information on the formation, decomposition, and mobility of polymer phases within single catalyst particles. Furthermore, the potential of fluorescence microscopy, X-ray microscopy and optical microscopy is highlighted for the high-throughput characterization of olefin polymerization and polyolefin decomposition catalysts. By combining these chemical imaging techniques with, for example, chemical staining methodologies, selective probe molecules as well as particle sorting approaches, representative structure-activity relationships can be derived at the level of single catalyst particles. A variety of laboratory- and synchrotron-based chemical imaging techniques can be employed to study heterogeneous catalysts at high spatial and temporal resolutions. This review discusses related advances in the fields of olefin polymerization and polyolefin decomposition catalysis and highlights future research directions that can ultimately deliver more detailed insights into structure-performance relationships in relevant catalyst materials.image

Automated summary

This review discusses the application of 2D and 3D chemical imaging techniques in the study of olefin polymerization and polyolefin decomposition catalysts. Laboratory and synchrotron-based chemical imaging techniques provide high spatial and temporal resolutions, expanding the analytical tools available in the field of heterogeneous catalysis and polymer science. Future research directions include in situ and operando (spectro-)microscopy experiments, as well as obtaining real-time information on the formation, decomposition, and mobility of polymer phases within single catalyst particles.