Abstract: The reactions of CO2 with H and CH3 radicals were systematically investigated using the quantum chemistry density functional theory. The reaction mechanism of CO2 with H and CH3 radicals was obtained. The pathway that H or CH3 radical attacked the C atom of CO2 was the preferential pathway in all the four designed reaction pathways. The main product was acetic acid, while methyl formate was inhibited by dynamics. The calculated result was in accordance with the experimental result, which provided a new illustration and guidance for the direct synthesis of oxygenated compounds from CH4 and CO2 by a two-step reaction method.

Key words: methane, carbon dioxide, acetic acid, hydrogen radical, methyl radical, quantum chemistry calculation