Thermal effects of organic porous media on absorption and desorption behaviors of carbon dioxide

As a result of global warming, people are increasingly concerned about greenhouse gas emissions, particularly carbon dioxide (CO₂). Many countries have been promoting carbon capture, storage (CCS) projects in order to alleviate climate degradation and achieve net zero carbon emissions. To study the thermal effects of organic porous media on CO₂ absorption and desorption, molecular dynamics coupled with Monte Carlo (MDMC) were used in this study. A part of the CO₂ molecules will be trapped within kerogen matrix due to its complex porous structure. The affinity of kerogen to CO₂ facilitates CO₂′s adsorption within the kerogen porous media, resulting in a heterogeneous distribution of CO₂. The kerogen forms high potential energy peaks and low potential energy wells in the matrix, which provide preferred adsorption sites for CO₂ in the porous space. The low stress state of CO₂ also indicates that it prefers adsorption in the matrix as CO₂ performs a lower potential energy state in the kerogen matrix than in the bulk phase. This study examines different thermal effects of kerogen, and results indicate that increasing CO₂ thermal motion facilitates its absorption, while a high temperature matrix promotes CO₂ desorption. Adsorbed layer provides resistance for CO₂′s diffusion behaviors. The free energy of CO₂′s diffusion is analyzed in relation to its mechanism, revealing that irregular thermal motion causes uncertainty in the adsorption capacity.