Variability of the data for CO2 absorption on coal reported by different research groups suggests that it strongly depends on experimental conditions. We investigated the effects of moisture content and pressure cycling history on temporal changes in the coal sorptive capacity for Pocahontas #3, Illinois #6, and Beulah Zap powders of Argonne premium coals. The samples were tested as received and moisture equilibrated at 96-97% RH and 55°C for 48 hours. It was demonstrated that the magnitude and dynamics of the changes are affected by the coal type (maceral) and rank. Correlation between the sample volume change (swelling/shrinkage) and the variations in absorption-desorption patterns may indicate the relationship between coal structural relaxation and kinetics of CO2 absorption. Experimental and theoretical methods are proposed to study these effects
