A Microporous Metal-Organic Framework with Unique Aromatic Pore Surfaces for High Performance C H /C H Separation.

Developing adsorptive separation processes based on C H -selective sorbents to replace energy-intensive cryogenic distillation is a promising alternative for C H purification from C H /C H mixtures, which however remains challenging. During our studies on two isostructural metal-organic frameworks (Ni-MOF 1 and Ni-MOF 2), we found that Ni-MOF 2 exhibited significantly higher performance for C H /C H separation than Ni-MOF-1, as clearly established by gas sorption isotherms and breakthrough experiments. Density-Functional Theory (DFT) studies showed that the unblocked unique aromatic pore surfaces within Ni-MOF 2 induce more and stronger C-H⋅⋅⋅π with C H over C H while the suitable pore spaces enforce its high C H uptake capacity, featuring Ni-MOF 2 as one of the best porous materials for this very important gas separation. It generates 12 L kg of polymer-grade C H product from equimolar C H /C H mixtures at ambient conditions.