1. Synthesis of Phase-Pure Interpenetrated MOF-5 and Its Gas Sorption Properties.
- Author
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Hyunuk Kim, Sunirban Das, Min Gyu Kim, Danil N. Dybtsev, Yonghwi Kim, and Kimoon Kim
- Subjects
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ORGANIC conductors , *GAS absorption & adsorption , *X-ray diffraction , *THERMOGRAVIMETRY , *ZINC , *ARGON , *X-ray crystallography - Abstract
For the first time, phase-pure interpenetrated MOF-5 (1) has been synthesized and its gas sorption properties have been investigated. The phase purity of the material was confirmed by both single-crystal and powder X-ray diffraction studies and TGA analysis. A systematic study revealed that controlling the pH of the reaction medium is critical to the synthesis of phase-pure 1, and the optimum apparent pH (pH*) for the formation of 1 is 4.0−4.5. At higher or lower pH*, [Zn2(BDC)2(DMF)2] (2) or [Zn5(OH)4(BDC)3] (3), respectively, was predominantly formed. The pore size distribution obtained from Ar sorption experiments at 87 K showed only one peak, at 6.7 Å, which is consistent with the average pore size of 1 revealed by single crystal X-ray crystallography. Compared to MOF-5, 1 exhibited higher stability toward heat and moisture. Although its surface area is much smaller than that of MOF-5 due to interpenetration, 1 showed a significantly higher hydrogen capacity (both gravimetric and volumetric) than MOF-5 at 77 K and 1 atm, presumably because of its higher enthalpy of adsorption, which may correlate with its higher volumetric hydrogen uptake compared to MOF-5 at room temperature, up to 100 bar. However, at high pressures and 77 K, where the saturated H2 uptake mostly depends on the surface area of a porous material, the total hydrogen uptake of 1 is notably lower than that of MOF-5. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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