Insights on the CO-PROX reaction mechanism with inverse CeO2/CuOx catalysts

The preferential CO oxidation (CO-PROX reaction) is a low-temperature strategy for the CO clean-up in H2 streams produced by steam reforming. While the most reported catalysts for this application are those based on CuO dispersed on CeO2 supports, this project deals with the so-called inverse configuration where CuOx is the support of CeO2 particles. In our laboratory, we have fabricated 3D-printed copper monoliths which act as efficient supports for inverse CeO2/CuOx catalysts. In a previous fundamental study, we have found that redox synergistic interactions controlling the activity are dependent on the particle size affinity of CeO2 and the CuOx support. The main goal of this project is to disentangle the redox processes occurring on the surface of the CeO2/CuO catalysts under the CO-PROX reaction progress, in powder-based and monolith catalysts. While conventional CuO/CeO2 catalysts have been thoroughly reported, there are still many gaps in the fundamental knowledge of inverse CeO2/CuOx configurations. With the near ambient pressure X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) experiments conducted in ALBA in O2+CO+H2 atmosphere, we aim to elucidate the Cu and Ce redox changes in a battery of CeO2/CuOx inverse catalysts with tunable CuOx particle sizes during the CO-PROX reaction. The collected insights will shed light in the underlying mechanisms of the CeO2/CuO catalysts. Next to the outputs we have garnered in our laboratory by means of in situ DRIFTS and O236 pulse isotopic experiments, we expect to resolve the critical activity descriptors in the performance of the CeO2/CuOx systems.