The ideal adsorbed solution theory model (IAST) was applied to predict the selectivity of binary mixtures of C2H6/CH4 and C3H8/CH4 on Ni(TMBDC)(DABCO)0.5, respectively. Firstly, dual-site Langmuir-Freundlich (DSLF) model was used to fit the single component adsorption isotherms of CH4/C2H6/C3H8at 298 K. [33] The fitting parameters and correlation coefficients R2 from DSLF model are listed in Table S2. The R2 of the fitting curves for CH4, C2H6 and C3H8 adsorption isotherms are up to 0.999, indicating the well description of the CH4, C2H6 and C3H8 adsorption behaviors on Ni(TMBDC)(DABCO)0.5 by DSLF model.