Interaction between water and CO2 in smectite clay studied by inelastic neutron scattering

Interactions between CO2 and clay attracts considerable interest in the scientific community. This is partly motivated by the presence of large amounts of clay in caprock formations that act as flow barriers in storage sites for CO2. However, sorption mechanisms of carbon dioxide by clays are not completely understood, and previous investigations remain controversial. One of the hypotheses for the driving mechanisms is the interaction between the gas and the residual H2O in the clay interlayer space. This interaction affect the kinetics of CO2 intercalation. By using inelastic scattering, we have identified a hitherto overlooked mechanism for CO2 adsorption in hectorite clays. We have demonstrate a valid new approach, where we study the mechanism for CO2 adsorption from the perspective of interlayer hydrogeneous species, hydroxides and water.