LAUSR

An exclusive trace of CH4 direct carboxylation with CO2 by a stepwise technology was investigated using in-situ FT-IR spectroscopy. The results showed that CH4 was dissociated to atomic hydrogen and M-CHx species on catalyst surface when it was first introduced in the system, then CO2 was inserted into the intermediate to direct carboxylate. Finally, the subsequent adsorption of CH4 provided active hydrogen for the species of previous surface reaction, thus leading to the formation of the product. It was also found that the first introduction of CO2 on the surface of the “clean” catalyst might likely react with surface H species, which had an irreversible effect on the catalytic activity of CH4.