Exploring the intrinsic mechanism of the effects of multicomponent gases on methane oxidation under explosion condition

To improve mine safety and production efficiency, it is essential to thoroughly understand the intrinsic mechanisms by which the mine environment affects methane (CH 4 ) explosions. This study explores the processes of chain initiation and the critical elementary reactions in CH 4 oxidation under varying temperatures and environmental conditions (O 2 /CO/CO 2 /H 2 O) through reactive molecular dynamics simulations. The findings suggest that in CO/CO 2 atmospheres, CO plays a dominant role in initiating the chain reaction for CH 4 explosions. Additionally, as the concentration of CO decreases, the time required to initiate the CH 4 reaction increases. CO 2 engages in the reaction CO 2 + H → CO + OH (R1) at high temperatures, thereby increasing the concentration of highly reactive OH radicals. In CO/H 2 O atmospheres, CO remains a dominant factor in the CH 4 explosion chain initiation, while H 2 O enhances the reaction by increasing OH radical content. In CO 2 /H 2 O atmospheres, the chemical equilibrium effects of CO 2 and H 2 O, along with the third-body effect of H 2 O, collectively inhibit the CH 4 reaction rate at low temperatures and high CO 2 concentrations. However, at higher temperatures, the reactivities of CO 2 and H 2 O are enhanced, generating OH radicals, which accelerates the CH 4 reaction. Furthermore, H 2 O competes with CO 2 for H radicals, inhibiting reaction R1. • The effects of multicomponent gases on CH 4 explosion were explored by ReaxFF-MD. • CO promotes CH 4 explosion by altering chain initiation pathway at low temperatures. • H 2 O promotes CH 4 explosion by increasing the concentration of OH radicals. • CO 2 produces OH radicals and increases the conversion of CH 4 at high temperatures. • The effects of multicomponent gases on CH 4 explosion vary with their mixing ratios.