This work explores the combination of microwave cavity perturbation (MCP) with the concept of iso-potential operando spectroscopy (IPOS). Together they form IPO-MCP, a method for measuring changes of the conductivity of a catalyst within a catalytic fixed bed reactor.
As a proof of concept, spatially resolved profiles of the dielectric properties, of the species and of the temperature were recorded during the reverse water gas shift reaction on a commercial catalyst of copper, zinc oxide and alumina.
The results reveal a linear relationship between the electronic structure and the activity along the catalyst packing. They demonstrate that hydrogen enhances the Q value significantly compared with carbon dioxide, which is in line with previous investigations.
The research motivates the further application of IPO-MCP to other catalytic systems in which distinct changes of the conductivity occur.
The study is a collaboration between the Institute of Chemical Reaction Engineering at Hamburg University of Technology and the Institute of Chemistry and Biochemistry at Freie Universität Berlin, with funding from the German Research Foundation and the Einstein Foundation Berlin.
Diego Espinoza, Neda Kazemi, Zoran Bondzio, Oliver Korup, Thomas Risse, Raimund Horn (2026). Iso-Potential Operando Microwave Cavity Perturbation: Spatial Conductivity Changes of a Cu/ZnO/Al₂O₃ Catalyst Inside a Fixed-Bed Reactor During Reverse Watergas Shift Reaction. Ind. Eng. Chem. Res. 65 (26), 13645-13654.
