摘要/Abstract
采用溶胶凝胶法制备了CeO2-ZrO2固溶体载体涂层, 再经浸渍法制备了高空速下性能较好的甲醇水蒸气重整制氢xCuO/CeO2-ZrO2/SiC整体催化剂. 采用X射线衍射(XRD)、比表面积测试(BET)、H2程序升温还原(H2-TPR)和X射线光电子能谱(XPS)等手段对催化剂进行了表征, 结果表明, 催化剂活性主要与Cu比表面积、活性组分与载体之间相互作用以及氧空穴量有关. 其中5%CuO/CeO2-ZrO2/SiC整体催化剂的Cu比表面积较大, 活性组分CuO与CeO2-ZrO2固溶体氧化物之间相互作用较强, 氧空穴量较多, 因此表现出较好的催化性能. 在反应温度为360 ℃、水醇物质的量比为1.2、甲醇水蒸气气体空速为4840 h–1的条件下, 甲醇转化率为89.9%, 产氢速率为1556 L•m–3•s–1. 与传统颗粒催化剂相比, SiC基整体催化剂的产氢速率更高, 更适用于高空速下的甲醇水蒸气重整制氢反应, 有利于小型化制氢反应器的集成.
关键词: 甲醇水蒸气重整, 氢气, 一氧化碳, 固溶体, 整体催化剂
Hydrogen proton exchange membrane fuel cell is considered as the most cleanest way with high energy efficiency of hydrogen energy utilization. However, the high storage and transportation cost of hydrogen can always be the important factors hindering its development. Fortunately, on-site hydrogen production from methanol steam reforming can effectively solve this problem, which has low reforming temperature and CO content in reforming gas. Monolithic catalyst, a kind of catalytic material, on which the active components loaded on the formed support are generally honeycombed structures with multiple parallel channels. Therefore, compared to the traditional beaded catalytic materials, the monolithic catalytic material has lower pressure drop and higher mass transfer efficiency, which means that the monolithic catalysts have a certain practical application prospect. Ceria-zirconia solid solution was prepared by the sol-gel method, then a series xCuO/CeO2-ZrO2/SiC catalysts were prepared by incipient-wetness impregnation method, and demonstrated considerable catalytic activity at high velocity reaction conditions. The catalyst samples were characterized by X-ray diffraction (XRD), BET specific surface area test, H2-temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) techniques. According to the results, we proposed that the catalytic performances are mainly effected by the surface area of Cu, the interaction between active component and support, and the amount of oxygen vacancy. Among those catalysts, 5%CuO/CeO2-ZrO2/SiC had relatively higher copper specific surface area, stronger interaction between CuO and support, more oxygen vacancies, thus showing better catalytic activity. When the reaction temperature reached 360 ℃, with a water/methanol molar ratio of 1.2, methanol and water total gas hourly space velocity of 4840 h–1, the methanol conversion reached 89.9%, and the H2 production rate was 1556 L•m–3•s–1. When compared with the traditional bead catalyst, monolithic catalyst seems to be more suitable for high space velocity methanol steam reforming reaction, also the SiC support is chemical stable and has favorable thermal conductivity, which avoiding the device volume increase caused by the additional heating device, thus facilitating the integration of minitype reactors for hydrogen generation.
Key words: methanol steam reforming, hydrogen, carbon monoxide, solid solution, monolithic catalyst
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