Mechanism and characterization model of supercritical CO2 adsorption on coals:a review

CO2geologic storage in deep unminable coal as an important option for CCS(CO2 capture and storage),has a highly potential to be a feasible approach for reduction of greenhouse gas and effective development of coalbed methane.In recent years,the CO2-ECBM pilot projects in China had become to consider deep coal seam as a target layer.The interaction between supercritical CO2 and coals had also attracted more amd more attentions.Moreover,the CO2 storage capacity of coals mainly depends on the adsorption of coals.As a result,the study on supercritical CO2 adsorption on coals has become a significant field in CO2-ECBM.Firstly,we recompiled large numbers of experimental resutls and models of supercritical CO2adsorption on coals and concluded that the change of supecritical CO2 density cause the abnormaly of excess adsorption curves.We also summurized the effects of moisture,maceral,coal rank,temperature and pore size on supercritical CO2 adsorption capacity.Secondly,we depicted the variation of supercritical CO2 adsorption rate affected by pressure,temperature,coal size and coal rank.Thirdly,based on various adsorption behavoirs in pores with differet sizes in coals,we pointed out the pore selection effect during supercritical CO2 adsorption on coals.The uncondensed nature and high density of supercritical CO2 resulted in various adsorption behavoirs in different pores.Last but not least,some possible research related to supercrritical CO2 on coals was presented.The aim of this study is to review the research progress of supercrtical CO2 adsorption on coals and provide a foundation and significance for a further understanding of mechanism and characterization model of supercritical CO2 adsorption on coals.