Highly Selective Quantum Sieving of D2 from H2 by a Metal–Organic Framework As Determined by Gas Manometry and Infrared Spectroscopy

• Published in: Journal of the American Chemical Society Vol. 135; no. 25; pp. 9458 - 9464
• Main Authors: FitzGerald, Stephen A, Pierce, Christopher J, Rowsell, Jesse L. C, Bloch, Eric D, Mason, Jarad A
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 26.06.2013
• Subjects: Deuterium - chemistry; Hydrogen - chemistry; Organometallic Compounds - chemistry; Quantum Theory; Temperature
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja402103u

The quantum sieving effect between D2 and H2 is examined for a series of metal–organic frameworks (MOFs) over the temperature range 77–150 K. Isothermal adsorption measurements demonstrate a consistently larger isosteric heat of adsorption for D2 vs H2, with the largest difference being 1.4 kJ/mol in the case of Ni-MOF-74. This leads to a low-pressure selectivity for this material that increases from 1.5 at 150 K to 5.0 at 77 K. Idealized adsorption solution theory indicates that the selectivity decreases with increasing pressure, but remains well above unity at ambient pressure. Infrared measurements on different MOF materials show a strong correlation between selectivity and the frequency of the adsorbed H2 translational band. This confirms that the separation is predominantly due to the difference in the zero-point energies of the adsorbed isotopologues.