Enhanced quantum sieving of hydrogen isotopes via molecular rearrangement of the adsorbed phase in chabazite

Coadsorption experiments reveal an unexpected increase of the D-2/H-2 selectivity with loading in pure silica chabazite at 47 K. This effect is correlated with the appearance of a step in the adsorption isotherms of H-2 and D-2. Grand canonical Monte Carlo simulations show that this phenomenon is related to a molecular rearrangement of the adsorbed phase induced by its strong confinement. In the case of a H-2 and D-2 mixture, this rearrangement favors the adsorption of D-2 having a smaller size due to quantum effects.