Hydrogen production via steam reforming of methanol on Cu/ZnO/ Al2O3 catalysts: Effects of Al2O3 precursors
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Abstract
A series of Cu/ZnO/Al2O3 catalysts were prepared by co-precipitation method. This research focuses on investigating the influence of different Al2O3 precursors on the catalyst structure through thorough structural characterization techniques. Additionally, the catalytic performance of these catalysts in methanol reforming for hydrogen production was systematically evaluated. The results indicate that the simultaneous co-precipitation of Al3+ with Cu2+ and Zn2+ leads to partial substitution of Cu-Zn in the basic carbonates by Al3+. This substitution forms a hydrotalcite-like structure and strengthens Zn-Al interactions. On the contrary, after the co-precipitation of Cu2+ and Zn2+, introducing the Al2O3 precursor has a positive effect on eliminating the adverse effects of Al3+ on Cu-Zn substitution in basic carbonates. This process promotes the Cu-ZnO interaction, facilitates the dispersion of CuO species, and enhances the reducibility of catalysts. It also improves the dispersion of Cu on the surface, and ultimately enhanced the catalytic activity. Notably, the catalyst prepared using pseudo-boehmite as the Al2O3 precursor exhibited the highest activity. Under the conditions of a H2O/CH3OH molar ratio of 1.2 and a reaction temperature of 493 K, methanol conversion reached 94.8%, and the H2 space-time yield was 97.5 mol/(kg·h). The catalyst activity remained relatively stable after continuous operation for 25 hours. Even after being heat-treated at 723 K for 10 h, the activity loss of the catalyst was only 5.37%.
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