A New Kind of Column Materials for Gas Chromatographic Hydrogen Isotope Separation

Hydrogen isotope separation on nickel-containing metal-organic framework@gama-alumina-based multicomponent composite packed column: Identification of individual role of each component

A new optimized multicomponent composite, Na₂Cr₂O₇/Na₂CrO₄/NaCl/MOF-74(Ni)@γ-Al₂O₃ (S₁/S_2/S₃/MOF-74(Ni)@γ-Al₂O₃. Na₂Cr₂O₇ = S₁, Na₂CrO₄ = S₂, NaCl = S₃), was prepared and used as a gas chromatography stationary phase for the separation of H₂ and D₂ isotopes. Under the optimal chromatographic separation conditions, the resolution of the packed column for the separation of H₂/D₂ was 2.87, and the separation time was 7.15 min at 77 K. The control experiments showed that in the multicomponent composite, MOF-74(Ni), which has a chemical affinity quantum sieving effect, played a major role in the separation of H₂/D₂. As the support of MOF-74, γ-Al₂O₃ enhanced the mechanical strength of MOF-74 and reduced the gas resistance. The presence of Na₂CrO₄ in the column increased the H₂/D₂ separation resolution, while the presence of NaCl reduced the separation time, produced more symmetrical and narrow chromatographic peaks of Gaussian distribution. Furthermore, by optimizing the ratio of NaCl and Na₂CrO₄, (S₂/S₃/MOF-74(Ni)@γ-Al₂O₃) composite with a NaCl/Na₂CrO₄ mass ratio of 0.7:1 was synthesized and used to realize the high-resolution separation of H₂/D₂ (R = 2.56) with a short separation time (t = 5.91 min). Both composites also showed excellent repeatability/reproducibility for separation.