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

Abstract

Molecular dynamics simulations using classical force fields were carried out to study the structural and transport properties of clay mineral–water–CO2 systems at pressure and temperature relevant to geological carbon storage. The simulations show that the degree of swelling caused by intercalation of CO2 strongly depends on the initial water content in the interlayer space and that CO2 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 CO2 trapped in montmorillonite. The origin of the shift is attributed to the electric field effects on the CO2 molecules induced by the water molecules.