Cryogenic gas chromatographic separation of hydrogen isotopes using pillared-layer MOFs composites as stationary phase

Abstract

Hydrogen isotopes are the main fuel in the fusion reactor, and the separation of hydrogen isotope gas mixture is the key process for the operation of fusion reactor. Cryogenic gas chromatography is an effective method which can be used for both separation and analysis of hydrogen isotopes. The chromatographic stationary phase determines the hydrogen isotopes separation performance. In this study, a series of pillared-layer MOFs Ni2(L)2 (dabco) (H2L: 1,4-benzenedicarboxylic acid (H2bdc), 1,4-naphthalenedicarboxylic acid (H2ndc), 9,10-anthracenedicarboxylic acid (H2adc); dabco: 1,4-diazabicyclo-[2.2.2]octane) were synthesized by changing the bridging dicarboxylate ligands with different steric hindrance. The effect of MOFs structure on hydrogen isotope interaction strength was studied by isothermal adsorption experiments of pure H2 and D2 at 77 K and 87 K, and programmed temperature desorption experiments of H2-D2 mixture from 25 K to 120 K. The enrichment factor for D2 over H2 up to 6.8 was obtained for Ni2(adc)2 (dabco) by static adsorption experiment of H2-D2 mixture. Finally, the MOFs composites Ni2(L)2 (dabco)@γ-Al2O3 were obtained by in situ solvothermal reaction loading MOFs on γ-Al2O3, and cryogenic gas chromatographic separation performance of H2-D2 and H2-HD-D2 mixtures using three composites-packed columns at liquid nitrogen temperature was investigated. The optimum separation was achieved when Ni2(adc)2 (dabco)@γ-Al2O3 was used as stationary phase due to strongest interaction strength with hydrogen isotope. The separation resolution R (H2/HD) and R (HD/D2) is up to 1.31 and 3.26 respectively.