Various key gas/vapors separations are accomplished using energy intensive processes as exemplified by the olefin/paraffin separation, an essential separation in chemical industry. Here we present our progress in the development of functional metal-organic frameworks (MOFs) to address some energy-intensive separations. Successful practice of reticular chemistry had afforded the fabrication of a chemically stable fluorinated MOF material (NbOFFIVE-1-Ni, also referred to as KAUST-7) that fully split propylene from propane. The bridging of Ni(II)-pyrazine square-grid layers with (NbOF5)2- pillars permitted the construction of a 3-dimensional MOF, enclosing a periodic array of fluoride anions in a contracted square-shaped channels. The judicious selection of the bulkier pillar (NbOF5)2- caused the looked-for hindrance of the previously free-rotating pyrazine moieties, delimiting the pore system and dictating the maximum opening of the pore aperture-size. The restricted MOF window resulted in the selective molecular exclusion of propane from propylene at atmospheric pressure, as evidenced by multiple cyclic mixed-gas adsorption and calorimetric studies. The deliberate control of the pore aperture-size of various selected MOFs and its impact on various separations will be discussed.

Functional metal-organic frameworks for the energy-intensive separations

253rd National Meeting (2017)

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