A comparative study of carbon dioxide adsorption on intact and crushed coal

Production of CO2 from fossil fuel combustion is a significant environmental concern. At present, major challenge has been set to reduce CO2 emissions below and equal to emission levels in 1990. One of the geological storage options being studied to assist in reducing CO2 emissions is the sequestration of CO2 in unmineable coal deposits. One of the technical issues associated with this storage technique is the lack of knowledge regarding adsorption characteristics of coalbed methane reservoirs. Kinematics of CO2 adsorption on in situ coal seams cannot be captured using crushed coal which is traditionally studied. The current research compares the CO2 adsorption behavior of crushed and intact coal specimens. Tests were carried out using a modified triaxial testing apparatus under an isotropic effective stress of 3.75MPa to simulate field conditions. Diffusion from the samples was minimized by putting them in copper membranes. Comparison of moisture content determined before and after the test validated the efficiency of the sealing mechanism. A different technique of constant pressure was used in this study as compared to constant volume approach in previous studies.; Comparison of results with the previous studies shows that the adsorption of CO2 on intact coal varied from that of crushed coal especially at lower CO2 equilibrium pressures and exhibits attenuated adsorption kinetics in comparison to crushed coal specimen.