Hydrogen isotopes (H2, D2 and T2) separation in cation exchange zeolite Y through chemical affinity quantum sieving

Separation of hydrogen isotopes is still a great challenge due to the nearly identical physicochemical properties of the isotopes, and existing separation technologies are highly energy and time-intensive with only a low separation factor. Here hydrogen adsorption selectivity of Ag(I)-exchanged zeolite Y (Ag(I)Y) have been systematically investigated via thermal desorption spectroscopy (TDS), which were compared with that of Cu(II) Y, NaY and HY zeolites. The TDS results reveal that D2/H2 selectivity on Ag(I)Y can be improved to 21.16 at 40 K, and D2/H2 selectivity of 9.12 can be obtained even at liquid nitrogen temperature. In addition, after three enrichment cycles, the D2 concentration can reach to 93.04 % and 96.59 % from 2.5 % at 77 K and 87 K, respectively. Nevertheless, such an obvious enhancement of isotope selectivity was not observed in the case of Cu(II) Y, NaY and HY zeolites. More importantly, the separation of deuterium–tritium isotopes in Ag(I)Y was carried out experimentally for the first time, and T2/D2 selectivity of 2.44 and 2.81 was obtained at 77 K and 87 K, respectively. Combination of results of differential phase contrast scanning transmission electron microscopy (iDPC-STEM), thermal desorption spectroscopy and difference in adsorption enthalpy, the large isotope selectivity of Ag(I)Y is attributed to the chemical affinity quantum sieving (CAQS) effect.