Al2O3前驱体对Cu/ZnO/Al2O3催化甲醇重整制氢性能的影响

Hydrogen production via steam reforming of methanol on Cu/ZnO/ Al2O3 catalysts: Effects of Al2O3 precursors

  • 摘要: 采用共沉淀法制备了一系列Cu/ZnO/Al2O3催化剂,通过XRD、BET、H2-TPR、N2O化学吸附、XPS表征技术,研究了Al2O3前驱体对催化剂结构的影响,同时对其在甲醇重整制氢中的性能进行了考察。结果表明,当Al3+与Cu2+、Zn2+同时共沉淀时,Al3+对碱式碳酸盐中Cu2+-Zn2+部分取代生成类水滑石结构,增强了Zn-Al之间的相互作用。相反,在Cu2+、Zn2+完成共沉淀后,引入Al2O3前驱体对消除Al3+对碱式碳酸盐中Cu-Zn取代的不良影响具有积极作用,有利于促进Cu-ZnO间的相互作用、CuO物种的分散和催化剂的还原,进一步促进表面Cu的分散,有利于其活性的提升。其中,以拟薄水铝石为铝源制备的催化剂呈现出优异的活性。在水醇物质的量比为1.2,反应温度为493 K的条件下,甲醇转化率可达94.8%,H2时空收率可达97.5 mol/(kg·h),并且连续运行25 h其活性仍保持相对稳定。在反应条件下,经过723 K的10 h热处理后,该催化剂的活性损失率仅为5.37%。

     

    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 h. 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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