Reasons for increased selectivity of catalysts for partial oxidation of methane using N2O as oxidizing agent

Abstract

It was found that the increase in the selectivity of catalysts of the partial oxidation of methane by nitrous oxide (compared with the oxidation by molecular oxygen) is due to the participation in the reaction of adsorbed oxygen anion radicals O·−, with which the differences in the reactivity of methane and its mild oxidation products are leveled out. With O2, the reactivity of methane is much lower than that of formaldehyde and methanol and, as a result, the selectivity is low, and a postoxidation of the partial oxidation products rapidly takes place. The formation of O·− is promoted by low concentrations of metal ions in the catalyst. The influence of the geometrical factor is thus also manifested: at low concentrations of the metal ions (M), the surface postoxidation of the adsorbed formaldehyde (the nonlinear stage) is hindered, which favors increase in the selectivity with respect to HCHO.