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.
In this paper, the Cu-Ce based catalyst using NbOPO 4 (Nb-P) as support was firstly employed for selective catalytic reduction (SCR) of NO by NH 3 . The experimental results had illustrated that such catalyst exhibited well SCR activity and N 2 selectivity within a wide temperature range of 200–450 °C. These superior performances could be mainly attributed to its improved textural properties and strong acidity derived from NbOPO 4 support. More importantly, the sulfur tolerance of the NbOPO 4 supported Cu-Ce sample was found greatly improved compared to TiO 2 and Ti-Nb supported samples, where above 80% SCR activity of Cu-Ce/Nb-P sample was obtained at 250 °C after 10 h reaction running in the presence of 100 ppm SO 2 . This fact was the result of the enhanced acidity and the strong interactions between Cu-Ce oxides and NbOPO 4 support, which could prevent the surface oxygen species from sulfation by SO 2 . As such, these oxygen species strongly associated with NbOPO 4 support still could activate adsorbed NH 3 to fulfill the SCR reaction cycle, leading to its better sulfur resistance. The work would provide some enlightenments to the development of NH 3 -SCR catalysts with high sulfur resistance at medium-high temperature.
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