High CO2 Selectivity of an Amine-Functionalized Metal Organic Framework in Adsorption-Based and Membrane-Based Gas Separations

Abstract

Molecular simulations were used to assess the potential of a new amine-functionalized metal organic framework (MOF), Zn-aminotriazolato-oxalate (Zn-Atz), in adsorption-based and membrane-based gas separations. Single-component adsorption isotherms for CO2, H2, CH4, and N2 were computed and compared with the available experimental isotherm data. The good agreement between experiments and simulations motivated us to predict adsorption equilibria and transport rates of CH4/H2, CO2/H2, CO2/CH4, and CO2/N2 mixtures in Zn-Atz. We then used this molecular-level information to evaluate adsorption selectivity, permeation selectivity, working capacity, gas permeability, and sorbent selection parameter of Zn-Atz for CH4/H2, CO2/H2, CO2/CH4, and CO2/N2 separations. The separation performance of Zn-Atz was compared with several other nanoporous adsorbents and membranes. Finally, the selectivity and permeability of mixed matrix membranes where Zn-Atz was used as filler particles were evaluated by combining molecular simulations and continuum modeling. Our results showed that this amine-functionalized MOF is a very good candidate especially for separation of CO2 from other gases both in adsorption-based and membrane-based separations due to its high affinity for CO2.