Perovskite-type oxides LaFe1−xCoxO3 for chemical looping steam methane reforming to syngas and hydrogen co-production

Abstract

Chemical looping steam methane reforming is a novel technology for syngas and hydrogen production. It’s very important to find suitable oxygen carriers with good reactivity and high agglomeration resistance for this process. In the present work, the perovskite-type oxides LaFe1−xCoxO3 with x=0.1, 0.3, 0.5, 0.7, 1.0 were used as oxygen carriers. The influence of Co doping on the characteristics and the stabilities of these perovskite-type oxides were investigated by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), Brunauer–Emmett–Teller (BET) surface area and fixed-bed experiments. All the as-prepared samples with various Co substitutions exhibited crystalline perovskite structure similar to LaFeO3. The surface adsorbed oxygen which is beneficial to the complete oxidation of CH4 increased as the Co substitution increase. From the point of view of the oxygen-donation ability, resistance to carbon formation, as well as hydrogen generation capacity, the optimal degree of Co substitution is x=0.3. Despite slight sintering, the perovskite-type oxide LaFe0.7Co0.3O3 showed very good regenerability during the twenty redox reactions. In the methane reduction stage, syngas with H2/CO molar ratio close to 2:1 was obtained in the twenty cycles with 85% of CH4 conversion, 43% of CO selectivity, and 50% of H2 selectivity. While in the steam oxidation stage, a steadily hydrogen productivity at about 4mmol/g oxygen carriers was generated.