An oxygen carrier catalyst toward efficient chemical looping-oxidative coupling of methane

Chemical looping concept paves way toward intrinsically safe and efficient oxidative coupling of methane (CL-OCM) process, because it permits the reaction to proceed via repeating reduction-oxidation cycle in two reactors. It is calling for a ground-breaking catalyst with enough high selective CH₄-converting lattice-oxygen carrying capacity but represents a grand challenge. Herein, we report an efficient catalyst obtainable by decorating an oxygen carrier FeMnO₃ with Na₂WO₄, with good cycling performance, achieving a high space time yield of 29.8 g_C2-C3 kg_cat.⁻¹ h⁻¹ with 20% CH₄ conversion and 80% C₂-C₃ selectivity at 800 °C and a low catalyst/CH₄ weight ratio of 13.5. CL-OCM process is established by “FeMnO₃ ↔ [MnFe₂O₄ + MnO]” redox cycle. Na₂WO₄-decoration gets lattice oxygen stored in FeMnO₃ transformed from non-selective to selective due to mitigation of lattice-oxygen evolution. Scaled up CL-OCM testing with 10-gram catalyst also yields comparable results seen in the case of using 1-gram catalyst, validating great application potential.