Effect of Nickel and Cobalt Doping on the Redox Performance of SrFeO3−δ toward Chemical Looping Dry Reforming of Methane

The low-content metal dopant in the oxides has a beneficial effect on the redox performance of these materials. However, the role of dopants remains elusive. Herein, SrFeO3−δ perovskites with low-content Ni or Co were investigated as oxygen carriers (OCs) for chemical looping dry reforming of methane. Compared with pristine SrFeO3−δ, the doped ones show an accelerated transition phase in the reduction step. As a result, doping causes an increase in both methane conversion and amount of lattice oxygen consumption. Among the OCs, SFO/01Ni with a Ni/Sr mole ratio of 0.001 exhibits superior performance. The possible mechanism for the optimal SFO/01Ni is linked to the synergistic effect between the enhanced migration of lattice oxygen and the improved catalytic performance resulted from the reduced metal particles and anchored Ni particles. In 20 tailored redox cycles at 900 °C, the productivity of H2 and CO over SFO/01Ni is always twice as high as that over SFO and SFO/01Co, suggesting that SFO/01Ni may sustain the periodically structural change in the bulk under the harsh reaction conditions. These findings advance the understanding of the role of non-noble dopants in methane oxidation over perovskites and may greatly inspire the rational OC design and exploration for chemical looping reforming.