Enhanced oxygen migration in tailored lanthanum-based perovskite for solar-driven dry reforming of methane

CO2 and methane are the first and second most important greenhouse gases (GHGs). Solar thermal chemical looping dry reforming of methane (STCL-DRM) is a promising route to reduce methane/CO2 emissions and achieve solar-to-chemical production. However, the lack of suitable oxygen carrier (OC) catalysts impedes the development. In this study, the tailored lanthanum-based perovskite by Cu and Ni substitution was synthesized as the OC catalyst. In the partial oxidation of methane, the tailored perovskite LaCu0.5Ni0.5O3 can be reduced at the temperature of 450 C-degrees-750 C-degrees, and later the consumed lattice oxygen was supplemented through CO2 reduction. Based on the DFT calculations, LaCu0.5Ni0.5O3 exhibited a lower oxygen vacancy formation energy of 0.78 eV and a lower energy barrier of 0.32 eV for the oxygen migration from the second to the first layer. Compared to the undoped lanthanum-nickel perovskite and ceria, LaCu0.5Ni0.5O3 shows superior oxygen migration ability. The enhanced oxygen migration and synergistic effect of Cu and Ni substitution were identified and unveiled through thermodynamic and computational study. The fixed-bed reactor tests yielded outstanding results with methane conversion >83 %, CO selectivity >97 %, and near-complete CO2 conversion at 650 C. Furthermore, we evaluated two pathways, STCL-DRM using LaCu0.5Ni0.5O3 and traditional steam methane reforming (SMR), for methanol/acetic acid production. The proposed STCL-DRM process using LaCu0.5Ni0.5O3 demonstrated 86 % reduction in energy demand compared to SMR while enabling negative CO2 production. This process showed a carbon efficiency of roughly 81.9 %, which was 5 % higher than traditional SMR. These results show that the STCL-DRM can provide a competitive route for realizing solar thermochemical CO2 reduction, clean conversion of methane, and efficient solar-to-chemical production.