The effect of copper oxide on the CuO-NiO/CeO2 structure and its influence on the CO-PROX reaction

The effect of copper oxide species on the CuO-NiO/CeO2 structure and the influence on the preferential CO oxidation in H-2 excess (CO-PROX) reaction at low and high temperatures were investigated. Temperature-programmed surface reaction (TPSR), In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and X-ray photoelectron spectroscopy (XPS) results allowed determining the surface species. The maximum temperature of CO2 formation or selectivity decreased about 40 degrees C for the CuO-NiO/CeO2 catalyst compared to the NiO/CeO2, which suggests that the addition of Cu+ species increases the active sites due to interaction with the Ni-Ce structure. Therefore, the activity of the catalyst was closely related to the oxygen in vacancies and the formation of Cu+ carbonyl species of the redox mechanism. Besides, the superior selectivity towards CO2 below 150 degrees C depends on the carbonyl stabilization at the surface, inhibiting the adsorption and subsequent oxidation of H-2. Using TPSR and spectroscopic analyzes by DRIFTS and XPS allowed us to propose the reaction mechanisms for low and high temperatures. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The effect of copper oxide species on the CuO-NiO/CeO2 structure and its influence on the preferential CO oxidation in H-2 excess reaction were investigated. The addition of Cu+ species increased the active sites and reduced the temperature of CO2 formation or selectivity. The stabilizing effect of carbonyl species inhibited the oxidation of H-2 and contributed to the superior selectivity towards CO2 at low temperatures.