A needle in a haystack: weeding out dead catalyst

Catalysts are important materials that are used to increase the resource and energy efficiency of chemical reactions and processes. Although catalysts operate in cycles that normally restore their initial activity over and over again, they do deactivate over time. ICC Researchers at Utrecht University and University of Twente have now developed a powerful analytical tool that marks “dead” catalyst particles for deletion, complemented with a technique to physically remove them from a stream of particles. The results were published in Nature Catalysis.

The authors explain: “Because the deactivation of catalyst particles is a heterogeneous process, picking out the dead catalyst particles from a large catalyst volume is like trying to find a bunch of needles in a haystack.” Weeding out deactivated particles means that only active catalyst material remains, thus ensuring cleaner and more efficient chemical reactions and processes.

The study was a joint research project of PhD candidates Anne-Eva Nieuwelink (Utrecht University, ICC) and Jeroen Vollenbroek (University of Twente), under supervision of Prof. Bert Weckhuysen (Utrecht University) and researchers from the MESA+ Institute at the University of Twente, including Prof. Mathieu Odijk and Prof. Albert van den Berg. The project is part of the NWO Gravitation Program MCEC.


The researchers came up with a novel method to mark the catalyst particles that are still active. That method relies on the staining reaction of catalyst particles with styrene-derivatives. The molecules become fluorescent when they react with an active site in the catalyst particle, which means that active particles light up, and dead particles do not. The mix of stained particles is then fed through a droplet microreactor, where the particles are sorted using an electrostatic field in as little as 200 milliseconds.

To check the accuracy of the sorting technique, the researchers analysed the sorted particles using micro-X-Ray fluorescence and fluorescence microscopy, which confirmed the success of the technique. Depending on the specific probe molecule used, the researchers report that the technique is 92-100% effective in picking out the most active particles.

Link to the UU press release.


High-throughput activity screening and sorting of single catalyst particles with a droplet microreactor using dielectrophoresis, Anne-Eva Nieuwelink*, Jeroen C. Vollenbroek, Roald M. Tiggelaar, Johan G. Bomer, Albert van den Berg, Mathieu Odijk and Bert M. Weckhuysen*, Nature Catalysis, 9 December 2021, DOI 10.1038/s41929-021-00718-7, (* ICC authors)