Nano-Perovskite-Based(LaMO_3)Oxygen Carrier for Syngas Generation by Chemical-Looping Reforming of Methane

Catalytic reforming of natural gas is a commercial process to produce syngas,which is the main source for the production of am-monia,methanol,hydrogen,and many other important products.This method produces also large amounts of CO2 as by-product.Chemical-looping reforming(CLR)is a novel technology that can be used for syngas production by partial oxidation and steam reforming of hy-drocarbon fuels.One key issue with the CLR concept that is being widely studied is the oxidation and reduction behavior of potential oxygen-carrier materials.Four perovskite-based nano-composite oxides were prepared by the sol-gel method and characterized by X-ray diffraction,N2 adsorption-desorption,scanning electron microscopy(SEM),and CH4 temperature-programmed surface reaction.The catalytic per-formance of the prepared samples for CLR of CH4 to syngas was investigated.The results showed that the LaMO3(B = Cr,Mn,Fe,and Co)oxides possess perovskite-type nano-composite structure.The oxidizing ability of these four perovskite oxides follows the order of LaCoO3 LaMnO3 LaFeO3 LaCrO3.Among them,LaFeO3 oxide has higher activity for CLR of CH4 to syngas.The CH4 conversion and CO selec-tivity are 89.6% and 98.9%,respectively.Especially,the sequential redox reaction revealed that the LaFeO3 oxide exhibits high stability with CH4 conversion of 60%～70% and CO selectivity of ～98% after 10 redox cycles.The SEM analysis revealed that the structure of the LaFeO3 oxide was not dramatically changed before and after 10 cyclic reactions.