CO2-free conversion of CH4 to syngas using chemical looping
Felix Donat, Christoph R. Müller
Abstract
Chemical looping can provide attractive alternative process routes in which solid oxygen carriers function as lattice oxygen transfer agents, for example for the partial oxidation of methane. We report on the development of a perovskite-based oxygen carrier (La0.85Sr0.15Fe0.95Al0.05O3-δ) that enables the complete conversion of CH4 to a synthesis gas (a mixture of H2 and CO, selectivity > 99 %) through donation of its lattice oxygen (up to 9 wt%) at temperatures > 900 °C. The thermodynamic properties of the oxygen carrier permit its lattice oxygen to be replenished with CO2 or H2O, of which > 94 % is converted into CO or H2, respectively. The potential of this compositionally and structurally flexible oxygen carrier is demonstrated in a continuous experiment lasting more than 45 days (∼ 4050 redox cycles), in which all CH4 (reductant) and all CO2 (oxidant) is converted into a synthesis gas without CO2 contamination.