Molecular pore-network model for nanoporous materials. I: Application to adsorption in silicon-carbide membranes

We develop a new model for nanoporous materials and inorganic membranes, the pore space of which consists of interconnected pores of irregular shapes and sizes. The model is based on the Voronoi tessellation of the atomistic structure of the crystalline or amorphous materials, of which the membrane is made. It generates three-dimensional molecular pore networks with pore size distributions (PSDs) that resemble those of real inorganic nanoporous materials. In addition to being interconnected and having irregular shapes and distributed sizes, the pores also have rough internal surface, which is what one may expect to exist in most real nanoporous materials. To test the validity of the model, we utilize it to compute the adsorption isotherms of nitrogen in three distinct silicon-carbide (SiC) membranes at 77 K, using equilibrium molecular dynamics simulations. Using at most one adjustable parameter, the simulated isotherms and the experimental data are found to be in very good agreement.