Preferential CO oxidation on highly active and stable ceria supported copper catalysts synthesized by a facile approach

Preferential CO Oxidation in H-2-rich streams is a promising approach to decrease CO concentrations below 10 ppm for fuel cell applications. Herein, Cu catalysts supported on commercial CeO2 are prepared by a simple ball-milling method with different Cu loadings (0.25, 0.5, and 1 wt%). The catalysts are characterized by various methods, including XRD, BET, STEM-EELS, and H-2-TPR. The results show that the catalysts are highly active and selective during CO-PROX in 80 vol% H-2-streams at different temperatures. Moreover, all catalysts exhibited high stability and 100 % CO2-selectivity throughout 75 h of reaction at 90 degrees C. However, increasing Cu loading caused a decrease in Cu-mass-normalized rate due to the formation of less active CuOx clusters. The combined results from operando DRIFTS, EPR and NAP-XPS reveal that single Cu atom sites on CeO2 are the key factor for the enhanced catalytic performance while the decreased activity is due to CuOx cluster formation.