Ni/CeO_(2)催化剂的金属-载体界面调控及其低温化学链甲烷干重整性能研究

Regulation of metal-support interface of Ni/CeO_(2) catalyst and the performance of low temperature chemical looping dry reforming of methane

本研究合成了四种CeO_(2)形貌的Ni/CeO_(2)催化剂(纳米棒、纳米立方体、纳米八面体和纳米多面体),并探讨了催化剂低温化学链甲烷干重整反应的结构依赖性。材料表征表明,Ni物种高度分散在CeO_(2)载体表面,部分Ni离子进入CeO_(2)晶格,从而引起氧空位的增加。化学链干重整性能测试结果表明,棒状结构Ni/CeO_(2)催化剂表现出最高的还原性,具有最多氧空位和最高储氧能力。多面体状Ni/CeO_(2)催化剂的结构为形状不规则的约10.3 nm的CeO_(2)纳米单晶,具有较大的比表面积和较高的还原性,表现出低温甲烷反应活性,在550℃低温化学链甲烷干重整中显示最高的氧化还原活性和循环稳定性。本研究为设计高效的金属/CeO_(2)催化剂提供了一种新策略,有望促进铈基催化剂在化学链技术中应用。

Interface regulation is an effective strategy to improve the interaction between carrier and active metal center,which can improve the catalytic activity and oxygen storage capacity of the catalysts.In this paper,Ni/CeO_(2) catalysts supported on CeO_(2) with different morphologies(nanorods,nanocubes,nanoctahedrons and nanopolyhedrons)were synthesized.The structure dependence of the catalysts for the low temperature chemical looping dry reforming of methane(CL-DRM)was investigated.The characterization results showed that Ni species were highly dispersed on the surface of CeO_(2) carrier,and some Ni ions entered the CeO_(2) lattice,resulting in the increase of oxygen vacancies.The Ni/ceria-rods catalyst had the highest reducibility,the most oxygen vacancies and the highest oxygen storage capacity.The irregular CeO_(2) nano single crystal of about 10.3 nm in the Ni/ceria-polyhedra led to high specific surface area and high reducibility which exhibited the highest redox activity and redox stability in low-temperature chemical looping dry reforming of methane at 550℃.This study provided a new strategy for the design of efficient metal/CeO_(2) catalysts,which was expected to promote the application of cerium-based catalysts in chemical looping technology.