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. Ce-2(WO4)(3)/CeO2 catalyst showed high OCM activity. In a periodic operation test over Ce-2(WO4)(3)/CeO2 catalyst, C-2 selectivity exceeded 60% during three redox cycles. However, Ce-2(WO4)(3)/CeO2 catalyst without the electric field showed low activity, even at 1073 K: CH4 Conv., 6.0%; C-2 Sel., 2.1%. A synergetic effect between the Ce-2(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 Ce-2(WO4)(3) (short W-O bonds in distorted WO4 unit) was consumed. The consumed oxygen was reproduced by a redox mechanism in the electric field.