Improved CO-PROX selectivity of CuO/CeO₂ catalysts by decorating with lanthanum via surface Cu⁺ redox site

Hydrogen purification is essential to satisfy the various purity requirements for different applications. Preferential oxidation of carbon monoxide (CO-PROX) is a promising strategy for removing CO from H-2-rich reformate in proton exchange membrane fuel cells (PEMFCs). Nonetheless, the large proportion of H-2 production via methanol steam reforming (MSR) will intensify oxidation competition between H-2 and CO, and the CO conversion and CO2 selectivity decrease considerably with increasing temperature. The tolerance of the PEMFCs against the CO species absorbed upon the surface presents the biggest dilemma. This work modified the conventional CuO/CeO2 catalyst in the CO-PROX by doping the support with lanthanum (La). CuO/La-CeO2 catalyst can effectively eliminate CO (<10 ppm) in 70 vol% H-2 and exhibit superior stability over 50 % selectivity in CO-PROX reaction. The surface properties of the catalyst before and after modification are characterized by XRD, N-2 isothermal adsorption-desorption, H-2-TPR, XPS, (HR)TEM Raman and Operando FT-IR, demonstrating that the La-CeO2 anchors CuO particle provides stable low-valence Cu sites (Cu xi+) with enhanced catalytic selectivity.