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

Abstract

Molecular dynamics simulations have been carried out to determine the Maxwell-Stefan diffusivity Ð 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, Γ ≡ ∂ ln f/∂ ln q. For diffusion in the large 1D pores of AFI, Ð is proportional to 1/Γ . In other zeolite topologies with smaller pore sizes, though such a direct proportionality is not observed, the Ð −q dependence appears to be closely linked to the 1/Γ−q characteristics, especially when the latter exhibits strong inflection.