Molecular Dynamics Simulations of Carbon Dioxide Intercalation in Hydrated Na-Montmorillonite

Molecular dynamics simulations using classical force fields were carried out to study the structural and transport properties of clay mineral–water–CO 2 systems at pressure and temperature relevant to geological carbon storage. The simulations show that the degree of swelling caused by intercalation of CO 2 strongly depends on the initial water content in the interlayer space and that CO 2 intercalation stimulates inner-sphere adsorption of the positively charged interlayer ions on the internal clay surfaces, which modifies the wetting properties of the surfaces. DFT-based molecular dynamics simulations were used to interpret the origin of the observed shift in the asymmetric stretch vibration of CO 2 trapped in montmorillonite. The origin of the shift is attributed to the electric field effects on the CO 2 molecules induced by the water molecules.