Research on CuO/CeO₂-ZrO₂/SiC Monolithic Catalysts for Hydrogen Production by Methanol Steam Reforming

Abstract

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.

Fabrication and Mechanism Study of Clustered Au/CeO2 Catalyst for the CO Oxidation Reaction★

“…催化 CO 氧化反应涉及反应物分子 O 2 的活化步 骤, 因此可还原性载体对于高效 CO 催化氧化反应是必 要条件 [11][12][13][14] . 由于 Ce 具有元素独特的 4f 轨道电子结构 ([Xe]4f 1 5d 1 6s 2 ), 从而立方萤石结构的 CeO 2 可以发生自 发 Ce 3 ＋ /Ce 4 ＋ 的变价行为, 产生表面富电子结构型 O 缺 陷(2Ce 4 ＋ ＋O→V O ＋2Ce 3 ＋ ＋1/2O 2 ), 为含 O 物种的活化 提供了丰富的活性位点 [8,12,[15][16] . 另一方面, 因其表面配 位不饱和等性质, 可调变其与活性金属间的相互作用, 调控活性金属的分散状态, 因此以 CeO 2 为载体的负载 型催化剂相关研究备受人们关注 [17] .…”

Effect of Controllable Pyrolysis of Ionomers in Fe-N-C Cathode Catalytic Layer on Cell Performance and Stability of Membrane Electrode Assembly★

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