The adsorption and diffusion behaviors of H2, CO2, CO, MeOH, and EtOH into ZIF-8 were studied in pure and mixtures (binary and total) states by grand canonical Monte Carlo and molecular dynamics simulation, respectively. In addition, the separation of MeOH over the other guest molecules was also investigated in the mentioned mixtures. The results of molecular dynamics simulations showed that the diffusion coefficients of pure guest molecules followed the trend of H2> CO2> CO > MeOH > EtOH. Analysis of adsorption indicated that all of the guest molecules (except H2) have S-shaped adsorption isotherms with an initial low-uptake region, which can be ascribed to the cage-filling phenomenon. However, the trend of the initial sorption plateau range is CO2> CO > MeOH > EtOH. In the mixture used guest molecules, the most separation is related to the separation of MeOH from H2 and EtOH, which is the optimal separation of MeOH from H2 at pressures less than 1584 kPa and the optimal separation of MeOH from EtOH at a pressure of 10,000 kPa.

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