Modeling permporometry of mesoporous membranes using dynamic mean field theory

Mesoporous inorganic membranes have significant potential for important small-molecule separations like carbon dioxide recovery from stack emissions. However, tailoring materials for a given separation remains an outstanding problem. Preferential adsorption, layering and capillary effects, and surface flow are key mechanisms that determine permeation rates and are ultimately linked to the mesopore characteristics. To further the understanding of these systems, a modeling approach based on dynamic mean field theory, which has previously been used to study the dynamics of adsorption in mesoporous materials, is proposed. This theory describes both relaxation dynamics and nonequilibrium steady states in membranes and is fully consistent with a mean field density functional theory of the thermodynamics. The capabilities and promise of the approach by modeling a permporometry experiment, in which a light gas permeates through a mesopore in the presence of a condensable vapor at a controlled relative pressure, are demonstrated.