载体形貌对Ni_(3)Fe/CeO_(2)催化剂甲烷干重整反应性能的影响

Effect of support morphology of Ni_(3)Fe/CeO_(2)on catalytic performance for dry reforming of methane

通过改变水热法条件合成了不同形貌CeO_(2)载体(棒状CeO_(2)-R、立方体CeO_(2)-C和多面体CeO_(2)-P),并用浸渍法制备了Ni_(3)Fe/CeO_(2)催化剂,继而研究了不同载体形貌Ni_(3)Fe/CeO_(2)催化剂对其甲烷干重整反应性能的影响。采用X射线衍射、N_(2)吸附-脱附、透射电镜、拉曼光谱、X射线光电子能谱、热重等对反应前后催化剂结构进行表征。结果表明,Ni_(3)Fe/CeO_(2)-R具有较大比表面积和较高的氧空位浓度,在甲烷干重整反应中表现出了优异的催化反应活性。800℃时,CH4和CO_(2)的转化率分别为82%和91%,且反应10 h性能稳定并且其积炭石墨化程度较低。同时,通过CeO_(2)-R载体氧空位对CO_(2)活化,有效抑制了对亲氧性Fe物种的过度氧化行为,反应前后催化剂Ni_(3)Fe合金结构保持稳定,具有良好的抗脱合金能力。

Different morphologies of CeO_(2)supports(including CeO_(2)-R rod,CeO_(2)-C cube,and CeO_(2)-P polyhedron)were synthesized by hydrothermal method and were used to develop Ni_(3)Fe/CeO_(2)catalysts by impregnation method for dry reforming of methane(DRM).The structures of the resultant catalysts before and after DRM were characterized by X-ray diffraction,N2 adsorption-desorption,transmission electron microscopy,Raman spectroscopy,X-ray photoelectron spectroscopy and thermogravimetry analysis.The results showed that Ni_(3)Fe/CeO_(2)-R exhibited good catalytic activity in DRM,where CH4 as well as CO_(2)conversion reached to 82%and 91%,respectively,at 800℃,owing to its large specific surface area and high oxygen vacancy concentration.The catalytic performance of Ni_(3)Fe/CeO_(2)-R was relatively stable and graphitic degree of coke deposition was low after 10 h.Meanwhile,the oxidative resistance of Ni_(3)Fe/CeO_(2)-R was improved as confirmed by the existence of stable Ni_(3)Fe alloy after reaction,which mitigated the facile oxidation of more oxyphilic Fe species on the alloy by the promotion of CO_(2)activation on the vacancies of CeO_(2)-R.