Effect of silica on generation and stability of Cu⁺ cations in CuO/CeO₂ catalysts for CO oxidation in H₂-rich atmosphere

Developing efficient CuO/CeO2 catalysts for CO preferential oxidation in H-2-rich atmosphere (CO PROX) is essential for removing residual CO in the reformate gas. However, achieving robust performance in a wide working temperature window is still a great challenge. Herein, SiO2 was introduced to modify the CuO/CeO2 catalysts and the best catalyst exhibited 100 % of CO conversion and >50 % of CO2 selectivity from 120 to 220 degrees C over CO PROX reaction. Combined characterization techniques demonstrate the enhanced interaction between copper species and CeO2 support after deposition of SiO2, promoting the generation of active Cu+ sites as well as the reactivity of lattice oxygen in CeO2 for CO conversion. Besides, in presence of SiO2, the main intermediates changed from carbonates to formate species. More importantly, the active Cu+ sites were stabilized by SiO2 due to formation of Cu+-O-SiOx interface, retarding the competitive H-2 oxidation at high temperatures.