Low temperature catalytic conversion of CH4, CO2, and C2H4 to value-added C3 oxygenates and olefins via C1-C2 coupling on Pd-Au/CeO2

The catalytic conversion of CH4 and CO2 in the presence of more reactive co-reactants C2H4 and O2 on Pd-Au/CeO2 is achieved at 200 °C and elevated pressures. Propene and acetone were produced from the catalyzed reaction of CH4 +C2H4 +O2; addition of CO2 to the reactant stream produced methyl acetate (MAc) but it significantly reduced the C-selectivities of propene and acetone. DRIFTS experiments confirmed the formation of methoxy species from CH4 +CO2 at 200 °C, which is an intermediate in the formation of MAc. Control experiments with blanks, and with CeO2 did not show any propene, acetone, or MAc products. The complete oxidation of C2H4 was avoided; the catalyst is stable, and reactant conversions and product yields were sustained for the observed 1200 min time-on-stream, indicating that there is little or no carbon deposition and sintering. This direct coupling of CH4 and C2H4 intermediates to higher carbon-number products at 200 °C is significant.