The enhancement effects of added methanol on methane-selective oxidation in the gas phase reaction of CH4–O2–NO2

Abstract

The reactivity of the selective oxidation of methane in the gas phase reaction of CH4–O2–NO2 was enhanced by the addition of a small amount of methanol. The selectivity of methanol produced at the same level of methane conversion was enhanced by adding a small amount of methanol in the feed gas. The enhanced effect of methanol addition was restricted to methane conversion in the presence of NO2. The enhancement effect was obtained more effectively when the ratio of methanol to NO2 was near to 1, at which higher concentration of both methanol and NO2 a significant enhancement was shown. Theoretical calculations concluded as follows: CH3OH + NO2→CH2OH + HNO2 was the predominant step of hydrogen abstraction from methanol. HO2 was then produced by CH2OH + O2→CH2O + HO2. CH4 + HO2→CH3 + H2O2 was the key reaction to enhance the reactivity of methane. HO2 + OH→H2O + O2 brought about an OH radical dissipation reaction to stabilize the produced methanol from the following decomposition reaction: CH3OH + OH→CH2OH + HO2 .