Experimental study on the competitive adsorption characteristics of N2, CO2 and O2 with various CO2/N2 blend ratios in coal

This study investigated the competitive adsorption of CO2, N-2, and O-2 with different CO2/N-2 ratios on residual coal. Isothermal adsorption experiments on DX coal with single and multi-component gases were conducted at 20-40 C-degrees and 0.1-1.0 MPa using a self-developed device. The results showed that O-2 and N-2 adsorption followed the Langmuir model, while CO2 adsorption fitted the D-R model; The adsorption capacity and isosteric adsorption heat of DX coal for single gases were: CO2>O-2>N-2; The adsorption capacity of O-2, N-2, and CO2 increased linearly with CO(2 )proportion under the same pressure, with correlation coefficients above 0.9; Higher temperature reduced CO2 adsorption more than O-2, decreasing the competitive selectivity of CO2 over O-2; At constant O-2 concentration, the average isosteric adsorption heat of coal adsorbing O-2 decreased with increasing CO2 proportion; At constant CO2/N-2 ratio, the average isosteric adsorption heat of coal adsorbing O-2 decreased with decreasing O-2 concentration.