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Quantum Sieving Effect of Three-Dimensional Cu-Based Organic Framework for H2 and D2

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journal contribution
posted on 21.05.2008, 00:00 by Daisuke Noguchi, Hideki Tanaka, Atsushi Kondo, Hiroshi Kajiro, Hiroshi Noguchi, Tomonori Ohba, Hirofumi Kanoh, Katsumi Kaneko
The crystal structure of [Cu(4,4′-bipyridine)2(CF3SO3)2]n metal-organic framework (CuBOTf) of one-dimensional pore networks after pre-evacuation at 383 K was determined with synchrotron X-ray powder diffraction measurement. Effective nanoporosity of the pre-evacuated CuBOTf was determined with N2 adsorption at 77 K. The experimental H2 and D2 adsorption isotherms of CuBOTf at 40 and 77 K were measured and then compared with GCMC-simulated isotherms using the effective nanoporosity. The quantum-simulated H2 and D2 isotherms at 77 K using the Feynman−Hibbs effective potential coincided with the experimental ones, giving a direct evidence on the quantum molecular sieving effect for adsorption of H2 and D2 on CuBOTf. However, the selectivity for the 1:1 mixed gas of H2 and D2 was 1.2. On the contrary, experimental H2 and D2 isotherms at 40 K had an explicit adsorption hysteresis, originating from the marked pore blocking effect on measuring the adsorption branch. The blocking effect for quantum H2 is more prominent than that for quantum D2; the selectivity for D2 over H2 at 40 K was in the range of 2.6 to 5.8. The possibility of the quantum molecular sieving effect for H2 and D2 adsorption on [Cu3(benzene-1,3,5-tricarboxylate)2(H2O)3]n of three-dimensional pore networks was also shown at 77 K.