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 Đ 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, Đ is proportional to 1/Γ. In other zeolite topologies with smaller pore sizes, though such a direct proportionality is not observed, the Đ – q dependence appears to be closely linked to the 1/Γ–q characteristics, especially when the latter exhibits strong inflection.