Co/CeO2 Catalysts Prepared Using Citric Acid Complexing for Ethanol Steam Reforming

Co/CeO2 catalysts with and without calcium doping were prepared by the citric acid complexing method, and characterized by N2 adsorption, X-ray diffraction, temperature-programmed reduction, Fourier transform infrared spectroscopy, and high resolution transmission electron microscope. Their catalytic performance measurement for ethanol steam reforming (ESR) at 400–650 °C and atmospheric pressure with a steam-to-carbon ratio of 3.0 and gas hourly space velocity of 50000 ml/(g·h) was measured. The citric acid complexing method enhanced metal-support interaction. The Co/CeO2 catalysts gave almost 100% ethanol conversion and good hydrogen yield at 500 °C. Calcium doping in the catalyst reduced the particle size of CeO2, but had little effect on the metallic cobalt size after reduction. Calcium doping higher than 5% deteriorated the redox properties and ESR catalytic performance, which was attributed to the fouling of CeO2 by CaO. Catalysts activated at 650 °C showed a better performance, which was due to a higher reduction degree of ceria and increase of the metal-oxide interface. Stability investigation of the catalysts suggested that 5% calcium doping enhanced carbon deposition resistance.

摘要采用柠檬酸络合法制备了 Co/CeO2 及其钙掺杂系列催化剂, 并对催化剂进行了低温 N2 物理吸附、X 射线衍射、H2 程序升温还原、傅里叶变换红外光谱、高分辨透射电镜表征以及乙醇水蒸气重整催化性能测试. 结果表明, 所制 Co/CeO2 催化剂具有良好的乙醇水蒸气重整催化性能, 500 oC 时乙醇能全部转化为 C1, 氢气产率高达 85% 以上. Ca 掺杂减小了载体 CeO2 纳米颗粒尺寸, 但对还原后 Co0 尺寸的影响较小. 当 Ca 掺杂量大于 5.0% 时, 催化剂氧化还原性能和乙醇水蒸气重整催化性能下降. 较高的还原温度有利于体相 Ce4+ 还原为 Ce3+, 并且提高了催化活性, 认为金属-氧化物边界的增加提高了催化活性. 初步稳定性考察结果表明, 5% 钙掺杂后的催化剂具有更好的抗积炭性能.

Co/CeO2 catalysts prepared by citric acid complexing showed good activity and stability for ethanol steam reforming to produce hydrogen for a proton exchange membrane fuel cell.Figure optionsDownload as PowerPoint slide