Breakthroughs in hard X-ray diffraction: towards a multiscale science approach in heterogeneous catalysis

Abstract

Diffraction at hard work: Modern heterogeneous catalysis would benefit from a multiscale science approach bridging the molecular world with the macroscopic world. Because of recent breakthroughs in X‐ray diffraction methods, including the surface X‐ray diffraction of atomically flat model catalysts, X‐ray diffraction tomography of catalyst bodies, and X‐ray profiling of an active catalyst in a chemical reactor, such an approach is now within reach.

Keywords: X-ray diffraction; heterogeneous catalysis; pair distribution function; surface analysis; synchrotron radiation.

Figure 1

Three recent reports are highlighted to show the potential of a multiscale science approach for studying heterogeneous catalysts at work with advanced X‐ray diffraction methods. a) An atomic model of a Pd surface during CO oxidation.2 b) A single diffraction image representing all of the images recorded during a rotational scan. Individual CTRs and superlattice rods are visible.2 c) Pd/Al₂O₃ catalyst body showing the particle size distribution measured by PDF‐CT.3 d, e) Experimental and fitted PDF data for single pixels at the edge (d) and in the interior (e) of the particle.3 f) Schematic representation of a capillary reactor used for the MTO reaction, showing the crystallographic changes as a function of the catalyst bed height. The color scale (from blue to red) indicates an expansion of the crystallographic c axis with increasing time on stream.4 g) Scatter plot of a z‐scan of the MTO reaction in a large reactor, compared to a line plot from capillary reactor data. Images are adapted from Ref. 2–4.