Preparation Of New Chromatography Stationary Phase Materials Mofs@γ-Al₂O₃ And Their Hydrogen Isotope H₂/D₂ Separation Performance

Hydrogen isotope H2/D2 separation on gas chromatography, because of its long chromatography column used, long separation time and low resolution between H2 and D2, it is necessary to study the H2/D2 chromatographic separation. The key point in H2/D2 separation on GC is the selection of stationary phase. Metal-organic frameworks (MOFs), which have higher H2/D2 separation selectivity, were chose to loaded on traditional H2/D2 separation materials alumina to improve the separation performance. Therefore, the composite material MOFs@γ-Al2O3 were prepared, and the H2/D2 separation performance was studied. The main achievements in this work obtained are listed below:(1) Metal-organic frameworks CPL-1, HKUST-1 and CPO-27-Co were loaded on γ-Al2O3 successfully with the method of in situ crystallizrtion, layer-by-layer and in situ hydrothermal forming CPL-1@γ-Al2O3, HKUST-1@γ-Al2O3 and CPO-27-Co@γ-Al2O3, respectively. The resulted composite materials were characterized by IR, ICP, XRD, SEM, EDS,TGA and N2 adsorption isotherm. And a possible growth mechanism of CPL-1 on γ-Al2O3 particles was proposed.(2) All of the three composite materials were packed into a 1.0 m length×2.0 mm i.d. stainless steel column as stationary phase, respectively. The performance of hydrogen isotope H2/D2 separation under liquid nitrogen temperature indicated that composite material HKUST-1@γ-Al2O3 shows a higher resolution 1.2 than pure @γ-Al2O3 (0.607), but still less than 1.5. The loading amount of HKUST-1 in HKUST-1@γ-Al2O3 and carrier gas flow rate of He have no obvious effect on H2/D2 separation. While to CPO-27-Co@y-Al2O3 composite material, the chromatograms give serious tailing peak of H2 and D2 when 150 mL·min-1 carrier gas flow rate of He was used, and the separation time of H2 and D2 reached to 12 min. What’s the worse, the resolution between H2 and D2 was only 0.85. However, to CPL-1@γ-Al2O3, the H2/D2 separation results shows that H2 and D2 can be separated completely. The resolution between D2 and H2 reached to 1.8 which is larger than 1.5. And the optimum CPL-1 loading amount in CPL-1@γ-Al2O3 was 11.76%, the optimum carrier gas flow rate was 120 mL·min-1. Quantity analysis of H2/D2 on CPL-1@γ-Al2O3 column under the optimum conditions was performed, and the results show that the relative standard deviation (RSD) of all the components are in 0.58-1.53%, and the relative errors are less than 0.05.