TY  - JOUR
A1  - Mondal, Suvendu Sekhar
A1  - Kreuzer, Alex
A1  - Behrens, Karsten
A1  - Schütz, Gisela
A1  - Holdt, Hans-Jürgen
A1  - Hirscher, Michael
T1  - Systematic experimental study on quantum sieving of hydrogen isotopes in metal-amide-imidazolate frameworks with narrow 1-D channels
JF  - ChemPhysChem : a European journal of chemical physics and physical chemistry
N2  - Quantum sieving of hydrogen isotopes is experimentally studied in isostructural hexagonal metal-organic frameworks having 1-D channels, named IFP-1, -3, -4 and -7. Inside the channels, different molecules or atoms restrict the channel diameter periodically with apertures larger (4.2 angstrom for IFP-1, 3.1 angstrom for IFP-3) and smaller (2.1 angstrom for IFP-7, 1.7 angstrom for IFP-4) than the kinetic diameter of hydrogen isotopes. From a geometrical point of view, no gas should penetrate into IFP-7 and IFP-4, but due to the thermally induced flexibility, so-called gate-opening effect of the apertures, penetration becomes possible with increasing temperature. Thermal desorption spectroscopy (TDS) measurements with pure H-2 or D-2 have been applied to study isotope adsorption. Further TDS experiments after exposure to an equimolar H-2/D-2 mixture allow to determine directly the selectivity of isotope separation by quantum sieving. IFP-7 shows a very low selectivity not higher than S=2. The selectivity of the materials with the smallest pore aperture IFP-4 has a constant value of S approximate to 2 for different exposure times and pressures, which can be explained by the 1-D channel structure. Due to the relatively small cavities between the apertures of IFP-4 and IFP-7, molecules in the channels cannot pass each other, which leads to a single-file filling. Therefore, no time dependence is observed, since the quantum sieving effect occurs only at the outermost pore aperture, resulting in a low separation selectivity.
KW  - gas adsorption
KW  - hydrogen isotopes
KW  - isotope separation
KW  - metal-organic frameworks
KW  - quantum sieving
Y1  - 2019
U6  - https://doi.org/10.1002/cphc.201900183
SN  - 1439-4235
SN  - 1439-7641
VL  - 20
IS  - 10
SP  - 1311
EP  - 1315
PB  - Wiley-VCH
CY  - Weinheim
ER  -