How catalysts age

PSI researchers have developed a new tomography method with which they can measure chemical properties inside catalyst materials in 3-D extremely precisely and faster than before. The application is equally important for science and industry. The researchers published their results today in the journal Science Advances.

The material group of vanadium phosphorus oxides (VPOs) is widely used as a catalyst in the chemical industry. VPOs have been used in the production of maleic anhydride since the 1970s. Maleic anhydride in turn is the starting material for the production of various plastics, increasingly including biodegradable ones. In industry, the catalytic materials are typically used for several years, because they play an important role in the chemical reactions but are not consumed in the process. Nevertheless, a VPO catalyst changes over time as a result of this use.

In a collaborative effort, scientists from two research divisions at the Paul Scherrer Institute PSI – the Photon Science Division and the Energy and Environment Division – together with researchers at ETH Zurich and the Swiss company Clariant AG, have now investigated in detail the ageing process of VPO catalysts. In the course of their research, they also developed a new experimental method.

Read more in the PSI website

Image: Zirui Gao, a researcher at PSI, has developed a new algorithm for experimental studies that significantly shortens the duration of certain imaging measurements that would otherwise take too long. The researchers used it to investigate ageing processes in a much-used catalyst material on the nanoscale.

Credit: Paul Scherrer Institute/Markus Fischer

X-ray Ptychography performed for first time at small-scale Laboratory Source

In recent years, X-ray ptychography has revolutionised nanoscale phase contrast imaging at large-scale synchrotron sources.  The technique produces quantitative phase images with the highest possible spatial resolutions (10’s nm) – going well beyond the conventional limitations of the available X-ray optics – and has wide reaching applications across the physical and life sciences. A paper published in Physical Review Letters on 12 May 2021, reveals that an international collaboration of scientists has demonstrated for the first time how the technique of high-resolution phase contrast diffraction imaging can be performed with small-scale laboratory sources.

The team from Diamond, Ghent University, University of Sheffield, and University College London conducted an experiment with a compact liquid metal-jet (LMJ) X-ray source. Laboratory X-ray sources have significantly lower levels of brilliance but currently provide the X-ray synchrotron user community with access to micro-CT, where they can gain a great deal of experience and produce preliminary data, at their home institutions. Until now, no such equivalent has existed for nano-scale imaging through coherent diffraction imaging and ptychography. The team’s paper outlines such an experiment and the first proof of concept for far field X-ray ptychography performed using an X-ray laboratory source. 

Read more on the Diamond website

Image: A reduced selection of the four-dimensional intensity data recorded during the experiment.

Credit: Diamond Light Source Ltd.