Low-temperature catalytic oxidative coupling of methane in an electric field over a Ce-W-O catalyst system

We examined oxidative coupling of methane (OCM) over various Ce-W-O catalysts at 423 K in an electric field. Ce₂ (WO₄)₃/CeO₂ catalyst showed high OCM activity. In a periodic operation test over Ce₂ (WO₄)₃/CeO₂ catalyst, C 2 selectivity exceeded 60% during three redox cycles. However, Ce₂ (WO₄)₃/CeO₂ catalyst without the electric field showed low activity, even at 1073 K: CH 4 Conv., 6.0%; C 2 Sel., 2.1%. A synergetic effect between the Ce₂ (WO₄)₃ structure and electric field created the reactive oxygen species for selective oxidation of methane. Results of XAFS, in-situ Raman and periodic operation tests demonstrated that OCM occurred as the lattice oxygen in Ce₂ (WO₄)₃ (short W-O bonds in distorted WO 4 unit) was consumed. The consumed oxygen was reproduced by a redox mechanism in the electric field.