Mixed Metal-Organic Framework with Multiple Binding Sites for Efficient C2H2/CO2 Separation

The separation of C2H2/CO2 is particularly challenging owing to their similarities in physical properties and molecular sizes. Reported here is a mixed metal-organic framework (M ' MOF), [Fe(pyz)Ni(CN)(4)] (FeNi-M ' MOF, pyz=pyrazine), with multiple functional sites and compact one-dimensional channels of about 4.0 angstrom for C2H2/CO2 separation. This MOF shows not only a remarkable volumetric C2H2 uptake of 133 cm(3) cm(-3), but also an excellent C2H2/CO2 selectivity of 24 under ambient conditions, resulting in the second highest C2H2-capture amount of 4.54 mol L-1, thus outperforming most previous benchmark materials. The separation performance of this material is driven by pi-pi stacking and multiple intermolecular interactions between C2H2 molecules and the binding sites of FeNi-M ' MOF. This material can be facilely synthesized at room temperature and is water stable, highlighting FeNi-M ' MOF as a promising material for C2H2/CO2 separation.