Molecular insights into shale gas adsorption: Thermodynamics, pore architecture, and CO₂ utilization in next-generation energy systems

• The detail explanation of the methane adsorption was fully elucidated • The factor affecting adsorption of methane in shale gas was explained in detail • The shale gas composition and different types are illustrated • The effect of pressure, temperature, relative humidity, porosity, and matrix type are fully explained As the world's need for reliable, environmentally friendly power grows, shale gas has become an important unconventional energy source. The process that controls the effectiveness of gas storage, transport, and recovery is known as adsorption, and it is fundamental to the extraction of shale gas. Adsorption takes place inside intricate nanoporous networks composed of organic and mineral substances. Methane adsorption, thermodynamics, pore structure, mineral composition, and competitive sorption with carbon dioxide (CO₂) are the main topics of this study, which summarizes recent progress in our knowledge of methane adsorption processes. Micropores, which have overlapped van der Waals contacts, may store more methane than larger holes because of the high temperature and pressure that characterize methane adsorption. Thermodynamic analyses show that adsorption is an exothermic, spontaneous process, and the fact that there is hysteresis between the two processes highlights how complicated confinement effects and pore connections are. Carbon dioxide-enhanced shale gas recovery (CO₂-ESGR) is based on CO₂'s competitive replacement of methane, which improves recovery and allows geological carbon sequestration. By combining microscopic interactions with macroscopic production projections, new molecular modeling techniques like molecular dynamics (MD) and grand canonical Monte Carlo (GCMC) simulations provide atomistic insights that go beyond classic adsorption models. Energy security, carbon management, and sustainable resource development are three areas where shale gas research is positioned, thanks to the combination of experimental investigations and sophisticated simulations that have shed light on adsorption thermodynamics, competitive processes, and transport phenomena.