Rocking chair-like movement of ex-solved nanoparticles on the Ni-Co doped La0.6Ca0.4FeO3-δ oxygen carrier during chemical looping reforming coupled with CO2 splitting

Abstract

Chemical looping reforming coupled with CO2 splitting is a promising CO2 utilization method that produces a valuable fuel. Here, we present a novel perovskite oxide with the composition of La0.6Ca0.4Fe0.95M0.05O3-δ (M = Ni, Co, Ni-Co) that functions both as an oxygen carrier and as a redox catalyst. Using a multi technique approach with HR-TEM, XRD, XAS, and Mössbauer spectroscopy, we find that alloy nanoparticles spontaneously form on the surface of Ni-Co doped carriers in a CH4 atmosphere, and as they are repeatedly exposed to CO2 and CH4 during the chemical loop, Fe atoms move back and forth between the inside (as Fe cations in the lattice) and the outside (as a part of metallic alloy) of the host scaffold. Eventually, the co-doped samples become highly reactive towards both gases and have excellent coking and redox stability, demonstrating record-level syngas yield (total ∼10 mmol/g) at 850 °C, over 50 redox cycles.