Effect of low-concentration steam on carbon dioxide adsorption by bituminous coal

A combination of experiments and molecular simulations was used to analyze the influence of different humidity values on the adsorption of CO2 on the surface of bituminous coal. First, the fixed bed dynamic adsorption method was used. A self-developed dynamic humidity control adsorption device was used to measure the penetration curves at different CO2 concentrations in the dry and wet states and to analyze the relevant dynamic processes. Second, molecular simulations were used to construct an amorphous cell model similar to the experimental sample, and the adsorption process and density distribution were simulated and analyzed. Finally, a comparative analysis of experimental and simulated data was performed. The results of the experiment showed that the CO2 adsorption of coal samples increased from 0.0291 mmol g−1 to 0.0871 mmol g−1 upon increasing the CO2 concentration. At low CO2 concentrations, the presence of water vapor inhibited CO2 adsorption on the surface of bituminous coal, advanced the CO2 breakthrough curve, and decreased the adsorption amount. This phenomenon gradually became more apparent upon increasing the CO2 concentration. When the CO2 concentration reached 4%, the adsorption reduction affected by water vapor reached the critical value of 5.5%, the adsorption capacity of the inhibited group was 0.0515 mmol g−1, and then the effect gradually weakened. When the CO2 concentration reached 7%, the adsorption capacity was almost unaffected by water vapor.