Abstract:

Rape pollen was used as a biological template to prepare ZnO with a multi-layered pore structure, and Cu/ZnO supported catalysts (bio-CZ-500) with different structures were prepared by dipping and reducing Cu on ZnO. The obtained Cu/ZnO catalyst (namely, bio-CZ-500 upon calcination under 500℃) exhibited a high methanol selectivity of 81% in CO₂ hydrogenation and the activity could remain almost unchanged over 100 h on stream. However, the Cu/ZnO catalyst prepared by a conventional deposition-precipitation method exhibited much lower methanol selectivity (50%) and a rapid deactivation within 12 h under the same operation conditions. Based on series of characterization results, including TEM, SEM, N₂ physisorption, FTIR, XRD, XPS, contact angle analysis, and temperature-programmed techniques, etc., it was revealed that the bio-CZ-500 catalyst had a hierarchically porous carbon structure, abundant Cu-ZnO active interfaces, and a relatively larger water contact angle. The relative hydrophobicity of the bio-CZ-500 catalyst surface could accelerate the desorption of the by-product H₂O, promote the transformation of reaction intermediates to methanol, and also inhibit the sintering of copper, which led to the enhancement of both methanol selectivity and catalyst stability. It is believed that this work will provide a novel synthetic strategy to fabricate highly efficient and stable Cu-based catalysts for industrial application.

Key words: bio-template, CO₂ hydrogenation, Cu/ZnO catalyst, Cu-ZnO interface, stability

摘要：

采用油菜花粉作为生物模板制备了具有多层次孔结构的ZnO，再通过浸渍还原法将Cu负载于ZnO上制备了具有不同结构的Cu/ZnO负载型催化剂（bio-CZ-500），研究发现在500℃条件下焙烧制备的bio-CZ-500催化剂在CO₂加氢反应中经过100 h测试活性几乎不变，同时甲醇选择性高达81%。相比之下，无生物模板制备的Cu/ZnO催化剂显示出较低甲醇选择性（50%），且催化剂在12 h内快速失活。通过透射电镜、扫描电镜、氮气吸脱附、红外光谱、X射线衍射、X射线光电子能谱、接触角测试、程序升温等表征技术揭示了bio-CZ-500催化剂具有多级孔碳结构、丰富的Cu-ZnO活性界面和较高的水接触角。催化剂的弱亲水性加快了副产物水的扩散，促进了中间体分解制甲醇，同时抑制了铜颗粒的烧结失活，从而提高甲醇的选择性与催化剂的稳定性。该工作为制备高效稳定的Cu基工业催化剂提供了新方法。

关键词: 生物模板, CO₂加氢, Cu/ZnO催化剂, Cu-ZnO界面, 稳定性