Theory and Modeling of Transport in Nanoporous Materials: From Microscopic to Coarse-Grained Descriptions

This review presents the state of the art on the theory, molecular simulation, and coarse-grained strategies applied to the transport of gases and liquids in nanoporous materials (pore size in the range 1 - 100 nm). Recent advances in the understanding of molecular diffusion and transport under thermodynamic gradients in nanoporous adsorbents are discussed with special emphasis on small molecules in zeolites, active carbons, metal organic frameworks, but also in nanoporous materials with larger pores such as ordered and disordered mesoporous oxides. We provide a description of the fundamentals and principles of the different atom-scale and mesoscopic methods as well as of the theoretical formalisms that can be used to address such an important problem. Special attention is paid to the investigation of different molecular transport coefficients - including the so-called self, collective and transport diffusivities - but also to the determination of free energy barriers and their role in overall adsorption/separation process rates. We also introduce other available approaches such as hierarchical simulations and upscaling strategies.