ReaxFF molecular dynamics investigation on the oxidation mechanism of Fe surface in supercritical CO2 mixed with O2

In the present study, the oxidation reaction of Fe surface in supercritical CO 2 (SCO 2 ) mixed with O 2 was studied at atomic scale by ReaxFF molecular dynamics simulation. The microscopic oxidation mechanism was explored, the charge evolution was observed and the effects of gas composition and temperature on the oxidation were determined. The results indicate that in the initial stage of the reaction, both of O 2 and SCO 2 molecules are adsorbed on the Fe surface, and O 2 reacts with Fe atoms prior to SCO 2 . The initial consumption rates of O 2 and SCO 2 increase with the increase of their content in the system. The reaction degrees of O 2 and SCO 2 increase with temperature. The consumption of SCO 2 is always greater than O 2 at different temperatures. The thermal motion of atoms rises significantly with the increase of temperature, which is beneficial to the oxidation reaction. The oxidation of Fe surface in SCO 2 mixed with and O 2 . • Oxidation mechanism of Fe surface in SCO 2 mixed with O 2 was explored at atomic scale. • Initial consumption rates of O 2 and SCO 2 increase with their content in the system. • Reaction degree of O 2 and SCO 2 increase with temperature.