The effect of pore sizes on D 2 /H 2 separation conducted by MOF-74 analogues

Four stable MOF-74 analogues, namely Ni 2 (dobdc), Ni 2 (dobpdc), Ni 2 (olz) and Ni 2 (dotpdc), possessing abundant open metal sites (OMSs) and honeycomb channels with pore sizes ranging from 1.0 to 2.6 nm, were used to research the effects of the pore size on D 2 /H 2 separation from the hydrogen isotope mixture through dynamic column breakthrough experiments. With respect to consideration of the chemical affinity quantum sieving (CAQS) effect and the competitive adsorption between Ne and hydrogen isotope in (H 2 /D 2 /Ne: 1/1/98) and (H 2 /D 2 /Ne: 10/10/80) mixtures, the microporous Ni 2 (dobdc) exhibits the longest breakthrough time periods of 240 and 36.4 min g −1 , respectively. In the (H 2 /D 2 : 50/50) mixture, mesoporous Ni 2 (olz) exhibits the longest breakthrough time of 15.0 min g −1 owing to its more accessible OMSs and diffusion rate of hydrogen isotope being inclined to adsorb heavier D 2 rather than H 2 . Hence, mesoporous MOFs with abundant OMSs may be ideal candidates for D 2 /H 2 separation.