电场耦合CuZnAlCe氧化物催化甲醇低温裂解制氢

    Electric Field-Coupled CuZnAlCe Oxide Catalysts for Low-Temperature Methanol Decomposition to Hydrogen

    • 摘要: 采用共沉淀法制备了一种碳化硅(SiC)混合的铈(Ce)改性铜–锌–铝复合氧化物催化剂(CuZn0.5Al0.2Ce-x),并研究其在电场作用下的甲醇裂解制氢性能与增效机制。结果表明,电场能直接驱动甲醇低温高效裂解,使反应温度由热化学状态下的300 ℃降至155 ℃以下(转化率>90%)。其中,Ce掺杂量为Cu的物质的量的5%的催化剂表现出最佳的催化活性:床层温度65 ℃时甲醇转化率达到50%;在300 mA电流条件下,床层温度105 ℃时甲醇转化率达到100%。通过X射线衍射仪(X-ray diffraction, XRD)、X射线光电子能谱仪(X-ray photoelectron spectroscopy, XPS)、H2程序升温还原(H2-temperature-pragrammed reduction, H2-TPR)及透射电子显微镜等表征手段,分析了电场中Ce掺杂量对催化剂微观结构和催化性能的影响。结果表明,适量Ce的引入有效改善了活性组分铜(Cu)的分散度,形成Cu–Ce高效电子转移界面,在电场的还原作用下,催化剂表面形成更多的Cu0位点及Ce3+不饱和位点,共同构成并维持高效的“Ce3+–Cu0”活性中心,协同提升甲醇的低温裂解性能。

       

      Abstract: A silicon carbide (SiC)-mixed, cerium (Ce)-modified copper–zinc–aluminum composite oxide catalyst (CuZn0.5Al0.2Ce-x) was prepared via the coprecipitation method. Its performance and enhancement mechanism for methanol decomposition to hydrogen under an electric field were investigated. The results demonstrate that the electric field directly drives efficient low-temperature methanol decomposition, reducing the reaction temperature from 300 ℃ under thermal conditions to below 155 ℃ with a conversion rate greater than 90%. Among the samples, the catalyst with a Ce/Cu molar ratio of 0.05 exhibited the highest activity, achieving a 50% methanol conversion rate at a bed temperature of 65 ℃, and reaching 100% conversion at 105 ℃ under a current of 300 mA. The effects of Ce doping on the microstructure and catalytic performance under the electric field were analyzed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy(XPS), H2-temperature-programmed reduction (H2-TPR), and transmission electron microscopy (TEM). The results indicate that an appropriate amount of Ce effectively improves the dispersion of the active copper (Cu) phase and facilitates the formation of an efficient Cu–Ce electron transfer interface. Under the reducing effect of the electric field, a higher density of Cu0 sites and Ce3+ unsaturated sites are generated on the catalyst surface. These sites together constitute and maintain highly active “Ce3+–Cu0” centers, which synergistically enhance the low-temperature methanol decomposition performance.

       

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