Enhanced lattice oxygen reactivity over Fe2O3/Al2O3 redox catalyst for chemical-looping dry (CO2) reforming of CH4: Synergistic La-Ce effect

Abstract

Chemical-looping dry (CO2) reforming (CLDR) of CH4 over the LaxCe1-x-Fe2O3/Al2O3 (x = 0, 0.33, 0.67, and 1) redox catalysts paves a novel path for efficient syngas production and intensive CO2 reduction. The isolation of CO2 splitting (CS) from partial oxidation of CH4 (POM) via the proposed CLDR process makes it possible to economically address the carbon deposition of significant concern in conventional dry reforming and other related applications, and meanwhile enable a straightforward determination of active phases involved in the cyclic CLDR operation. Owing to the rare earth (i.e., La and Ce) incorporations and intimate contacts among the active Fe species, a large amount of perovskite (LaFeO3 and CeFeO3)-derived oxygen defects along with CeO2-assisted surface dispersion improvement hammer out tunnels beneficial for lattice oxygen migration, hence constituting the synergistic La-Ce effect. Moreover, our findings reveal that such La-Ce effect is advantageous for enhancing the resistance of Fe2O3/Al2O3 redox catalyst toward particle sintering and formation of inactive carbon, which guarantees catalyst tolerance against accumulated carbon deposition and more importantly the effective CO2 activation for both lattice oxygen replenishment and carbon removal. Herein, our findings demonstrate the potential of utilizing LaxCe1-x-Fe2O3/Al2O3 (x = 0.33) as a most promising redox catalyst for the proposed CLDR process.