柠檬酸络合法制备的Co/CeO_2催化剂上中温乙醇水蒸气重整性能(英文)

Co/CeO_2 Catalysts Prepared Using Citric Acid Complexing for Ethanol Steam Reforming

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,500oC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 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 oC 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 oC.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 oC showed a better performance,which was due to a higher reduction degree of ceria and increase of the metal-oxide inter-face.Stability investigation of the catalysts suggested that 5% calcium doping enhanced carbon deposition resistance.