Solvent-mediated synthesis and catalytic performance of oxalate gel-derived CuO/ZnO/Al2O3 catalysts for hydrogen production via methanol steam reforming

The influence of solvent engineering during oxalate gel co-precipitation on the physicochemical properties and catalytic performance of CuO/ZnO/Al₂O₃ (CZA) catalysts for methanol steam reforming was systematically investigated. Catalysts were synthesized using ethanol, ethylene glycol, diethylene glycol (DEG), triethylene glycol, and propylene glycol, followed by characterization using XRD, FESEM, EDX-mapping, FTIR, and BET analyses. Solvent selection markedly affected catalyst microstructure, phase dispersion, morphology, and specific surface area. Among the prepared catalysts, the DEG-derived sample exhibited the smallest CuO crystallites, the highest specific surface area, and the most homogeneous morphology, resulting in superior catalytic performance. It achieved approximately 51% methanol conversion at 160 °C and nearly complete conversion above 220 °C, while maintaining CO selectivity below 1.5% up to 300 °C and excellent stability over 24 h. These findings demonstrate that solvent engineering provides a simple and effective strategy for optimizing Cu-based catalysts for efficient hydrogen production via methanol steam reforming.