Insights into the structure-performance relationship of CuOx-CeO2 catalysts for preferential oxidation of CO: Investigation on thermally induced copper migration process

Abstract

A series of CuOx-CeO2 catalysts is designed by coating composite copper-ceria precursor with different thickness of CeO2, followed by thermal treatment at 500 and 700 °C respectively to investigate the outward migration phenomenon of Cu species induced by high temperature thermal treatment. For the CuOx-CeO2 catalysts calcined at 500 °C, the coating of CeO2 covers the active surface Cu entities and degrades the low temperature catalytic performance for preferential oxidation of CO (CO-PROX). However, thermal treatment at 700 °C induces the migration of large amounts of Cu entities from bulk to the surface of CeO2 nanoparticles and recovers the low temperature catalytic performance. In addition, 700 °C thermal treatment of CuOx-CeO2 catalyst without CeO2 coating causes excessive outward migration of Cu species and severe CuO agglomeration, which decreases the catalytic performance at low reaction temperature, but broadens the high temperature operation window on account of the formation of inverse CeO2-CuO structure. This work provides deeper insight into the regime of thermally induced Cu migration phenomenon, and illuminated the structure-performance relationship of copper-ceria based catalysts for CO-PROX.