Enhancing Preferential CO Oxidation of Cu–Ce/γ-Al2O3 Catalyst Through an Acid-Modified Method

The development of efficient Cu–Ce catalysts for selective CO oxidation in hydrogen streams (CO-PROX) remains a critical challenge for hydrogen purification technologies. Herein, we report an acid-modified Cu–Ce/γ-Al2O3 catalyst synthesized through HCl-assisted wet impregnation and thermal aging, demonstrating exceptional low-temperature CO-PROX performance. The optimized CuCe0.8(Cl)0.2/γ-Al2O3 catalyst achieves superior CO conversion below 160 °C and maintains stable activity for 50 h at 160 °C. Mechanistic studies reveal that HCl modification induces dual enhancement effects: (1) increased Cu+ species density enhances CO adsorption capacity; (2) elevated Ce3+ concentration promotes oxygen vacancy formation for efficient O2 activation. Complementary characterization demonstrates that the acid treatment optimizes the active species dispersion and creates hierarchical pore structures in the γ-Al2O3 support, which facilitates reactant accessibility and stabilizes catalytic intermediates. The reaction mechanism involves synergistic cooperation between Cu+-mediated CO adsorption, oxygen vacancy-assisted O2 activation, and hydroxyl-assisted bicarbonate intermediate formation on the alumina support. This work establishes an effective acid-modification strategy for designing durable CO-PROX catalysts, advancing the development of a practical hydrogen purification system.