Al_(2)O_(3)前驱体对Cu/ZnO/Al_(2)O_(3)催化甲醇重整制氢性能的影响

Hydrogen production via steam reforming of methanol on Cu/ZnO/Al_(2)O_(3)catalysts:Effects of Al_(2)O_(3)precursors

采用共沉淀法制备了一系列Cu/ZnO/Al_(2)O_(3)催化剂,通过XRD、BET、H_(2)-TPR、N_(2)O化学吸附、XPS表征技术,研究了Al_(2)O_(3)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Al^(3+)与Cu^(2+)、Zn^(2+)同时共沉淀时,Al^(3+)对碱式碳酸盐中Cu^(2+)-Zn^(2+)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Cu^(2+)、Zn^(2+)完成共沉淀后,引入Al_(2)O_(3)前驱体对消除Al^(3+)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%,H_(2)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%。

A series of Cu/ZnO/Al_(2)O_(3)catalysts were prepared by co-precipitation method.This research focuses on investigating the influence of different Al_(2)O_(3)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 Al^(3+)with Cu^(2+)and Zn^(2+)leads to partial substitution of Cu-Zn in the basic carbonates by Al^(3+).This substitution forms a hydrotalcite-like structure and strengthens Zn-Al interactions.On the contrary,after the co-precipitation of Cu^(2+)and Zn^(2+),introducing the Al_(2)O_(3)precursor has a positive effect on eliminating the adverse effects of Al^(3+)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 Al_(2)O_(3)precursor exhibited the highest activity.Under the conditions of a H_(2)O/CH3OH molar ratio of 1.2 and a reaction temperature of 493 K,methanol conversion reached 94.8%,and the H_(2)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%.