Rapid diffusion of H2 and strong adsorption of D2 in Ni-4PyC realized the efficient separation of H2/D2 by gas chromatography

In this work, Ni-4PyC was selected as the material for the separation of hydrogen isotopes H-2/D-2, and the mechanism of hydrogen isotope H-2/D-2 separation was investigated by molecular simulation. The results showed that the adsorption selectivity of Ni-4PyC for D-2/H-2 increased from 1.26 to 1.46 when the temperature was decreased from 77 K to 20 K, indicating that Ni-4PyC effected chemical affinity quantum sieving on D-2/H-2. Also, the diffusion rates of H-2/D-2 were different at different temperatures. At 20 K, the kinetic selectivity of D-2/H-2 reached 1.30, indicating that Ni-4PyC had a kinetic quantum sieving effect on D-2/H-2 at low temperatures. However, when the temperature was higher than 30 K, the diffusion rate of H-2 was faster than that of D-2, and when the temperature was 77 K, Ni-4PyC exhibited the kinetic sieving effect with a kinetic selectivity of 1.59 for H-2/D-2. Due to the chemical affinity quantum sieving and kinetic sieving effects of Ni-4PyC on H-2/D-2, the adsorption capacity of Ni-4PyC for D-2 was better than that for H-2 and the diffusion rate of H-2 was faster than that of D-2 at 77 K. Therefore, Ni-4PyC was expected to achieve the separation of H-2/D-2. In order to verify the accuracy of the theoretical calculation results, an Ni-4PyC@& gamma;-Al2O3 composite material was synthesized by a liquid phase epitaxy method and was used to separate H-2/D-2 at 77 K in a 0.6 m x 2 mm chromatographic column. Under optimal separation conditions, the resolution R reached 1.84 with a separation time t = 7.47 min. In addition, Ni-4PyC@& gamma;-Al2O3 showed excellent separation performances for different ratios of H-2/D-2 mixtures. The stationary phase was repeatable and reproducible.