On the characterization of nanoporous materials by means of empirical and intrinsic transport coefficients

Abstract

Nanoporous materials need to be classified and characterized both for scientific research and applications in industrial production and environmental protection. Nanoporous materials with simple geometries (e.g. channel pores, slit pores) can be characterized by means of transport coefficients such as diffusion and viscosity coefficients of the fluid and gas flows through these materials. To this end, empirical transport coefficients defined by the Einstein relation and the Green–Kubo formula are frequently used. In the present study, it will be shown that the applicability of empirical transport coefficients is limited because of the confinement of fluid molecules in nanopores and the direct and indirect molecule–molecule interactions. It will be advocated that transport properties of nanoporous materials are better described by transport coefficients different from empirical transport coefficients such as intrinsic transport coefficient defined by Brownian dynamics models.

Key Words:

• Nanoporous materials
• Transport coefficients
• Data analysis
• Drift and diffusion estimates