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Separation of CO2/CH4 mixtures was studied in carborane-based metal–organic framework materials with and without coordinatively unsaturated metal sites; high selectivities for CO2 over CH4 (∼17) are obtained, especially in the material with open metal sites. [ABSTRACT FROM AUTHOR]

A Cu–carborane-basedmetal–organic framework (MOF), NU-135, which containsa quasi-spherical para-carborane moiety, has beensynthesized and characterized. NU-135exhibits a porevolume of 1.02 cm3/g anda gravimetric BET surface area of ca. 2600 m2/g, and thusrepresents the first highly porous carborane-based MOF. As a consequenceof the unique geometry of the carborane unit, NU-135hasa very high volumetric BET surface area of ca. 1900 m2/cm3. CH4, CO2, and H2adsorptionisotherms were measured over a broad range of pressures and temperaturesand are in good agreement with computational predictions. The methanestorage capacity of NU-135at 35 bar and 298 K is ca.187 vSTP/v. At 298 K, the pressure required to achievea methane storage density comparable to that of a compressed naturalgas (CNG) tank pressurized to 212 bar, which is a typical storagepressure, is only 65 bar. The methane working capacity (5–65bar) is 170 vSTP/v. The volumetric hydrogen storage capacityat 55 bar and 77 K is 49 g/L. These properties are comparable to thoseof current record holders in the area of methane and hydrogen storage.This initial example lays the groundwork for carborane-based materialswith high surface areas. [ABSTRACT FROM AUTHOR]