Linking the loading dependence of the Maxwell-Stefan diffusivity of linear alkanes in zeolites with the thermodynamic correction factor

Molecular dynamics simulations have been carried out to determine the Maxwell-Stefan diffusivity D of C1-C4 linear alkanes for a range of molecular loadings, q, in AFI, MOR, MTW, and MFI zeolites. Configurational-Bias Monte Carlo simulations were used to determine the thermodynamic correction factor, Gamma partial derivative 1n f/partial derivative 1n q. For diffusion in the large ID pores of AFI, D is proportional to 1/Gamma. In other zeolite topologies with smaller pore sizes, though such a direct proportionality is not observed, the D-q dependence appears to be closely linked to the 1/Gamma-q characteristics, especially when the latter exhibits strong inflection. (c) 2006 Elsevier B.V. All rights reserved.