Espinoza, DiegoDiegoEspinozaKazemi, NedaNedaKazemiBondzio, ZoranZoranBondzioKorup, OliverOliverKorupRisse, ThomasThomasRisseHorn, RaimundRaimundHorn2026-06-292026-06-292026-06-25Industrial & Engineering Chemistry Research (in Press): (2026)https://hdl.handle.net/11420/63657This work explores the combination of Microwave Cavity Perturbation (MCP) with the concept of Iso-Potential Operando Spectroscopy (IPOS) to develop IPO-MCP for measuring conductivity changes in a catalyst within a catalytic fixed-bed reactor (FBR). As proof-of-concept, spatially resolved dielectric properties, species, and temperature profiles were recorded during the reverse water–gas shift (rWGS) reaction on a commercial copper–zinc-alumina (CZA) catalyst. These results reveal a linear electronic structure–activity relationship along the catalyst packing demonstrating that hydrogen significantly enhances the Q-value compared to carbon dioxide in line with previous investigations. This research motivates further application of IPO-MCP to other catalytic systems with distinct conductivity changes.en1520-5045Industrial & engineering chemistry research2026American Chemical Society (ACS)https://creativecommons.org/licenses/by/4.0/Natural Sciences and Mathematics::541: Physical; Theoretical::541.3: Physical ChemistryTechnology::660: Chemistry; Chemical EngineeringIso-potential operando microwave cavity perturbation–spatial conductivity changes of a Cu/ZnO/Al₂O₃ catalyst inside a fixed-bed reactor during reverse watergas shift reactionJournal Articlehttps://doi.org/10.15480/882.1736910.1021/acs.iecr.6c0113710.15480/882.17369