Computational study of adsorption and separation of CO ₂, CH ₄, and N ₂ by an rht-type metal-organic framework

In this work, a computational study is performed to evaluate the adsorption-based separation of CO ₂ from flue gas (mixtures of CO ₂ and N ₂) and natural gas (mixtures of CO ₂ and CH ₄) using microporous metal organic framework Cu-TDPAT as a sorbent material. The results show that electrostatic interactions can greatly enhance the separation efficiency of this MOF for gas mixtures of different components. Furthermore, the study also suggests that Cu-TDPAT is a promising material for the separation of CO ₂ from N ₂ and CH ₄, and its macroscopic separation behavior can be elucidated on a molecular level to give insight into the underlying mechanisms. On the basis of the single-component CO ₂, N ₂, and CH ₄ isotherms, binary mixture adsorption (CO ₂/N ₂ and CO ₂/CH ₄) and ternary mixture adsorption (CO ₂/N ₂/CH ₄) were predicted using the ideal adsorbed solution theory (IAST). The effect of H ₂O vapor on the CO ₂ adsorption selectivity and capacity was also examined. The applicability of IAST to this system was validated by performing GCMC simulations for both single-component and mixture adsorption processes.