Diffusion in microporous materials with embedded mesoporosities

Diffusion properties of hierarchical micro-mesoporous material, i.e. microporous materials with embedded mesoporosities, have been studied using computer modeling. Under external conditions corresponding to the mesopores containing gaseous phase, the simulations have revealed strong dependence of the effective diffusivities on the interconnectivity of the mesopores for materials with sufficiently low diffusivities in the parent microporous material. As a consequence, this phenomenon is shown to lead to quite different activation energies for diffusion at high gas densities. These predictions are found to be in nice agreement with the data on microscopic diffusivities as obtained using pulsed field gradient NMR. (C) 2013 Elsevier Inc. All rights reserved.