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 degrees 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 degrees C, which is an intermediate in the formation of MAc. Control experi-ments 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 degrees C is significant.