Research on the mechanism of coal adsorption of CO2 hindering oxygen

This paper investigates the inhibitory effect of CO2 on oxygen adsorption during the low-temperature oxidation of coal. Taking the example of Tingnan coal, the physical adsorption barriers of CO2 during coal oxidation at different temperatures were analyzed in terms of competitive adsorption curves, adsorption capacity, adsorption selectivity and diffusion coefficients using a combination of indoor experiments and molecular simulations. It is proposed that the competitive adsorption advantage of CO2 is significantly greater than that of O2, and it is negatively correlated with temperature. Additionally, the variations of aliphatic gas-phase products are evident during the pre-oxidation temperature stages. When the pre-oxidation temperature exceeds 70 °C, the amounts of CH4 and C2H4 released increase with the pre-oxidation temperature, and the inhibitory effect of injected CO2 deteriorates. The simulation results validate the experimental conclusions and are in line with the actual situation, providing auxiliary optimization and guidance for coal mine fire prevention work. •The competitive adsorption law of O2 and CO2 under the dual effect of temperature and pressure was obtained.•CO2 exhibits an inhibitory effect on the system activity in the coal pore model.•There were large differences in the inerting inhibition effects after CO2 injection at different temperature stages.•The main reason for the difference in the effect of CO2 oxygen barrier adsorption with increasing temperature was obtained.