The quantum sieving effect between D-2 and H-2 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 D-2 vs H-2, 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 H-2 translational band. This confirms that the separation is predominantly due to the difference in the zero-point energies of the adsorbed isotopologues.