M-MOF-74 吸附分离 H₂/He 混合物的分子模拟研究

In order to explore whether the organometallic framework MOF-74 can be used as an excellent solid adsorbent to separate H₂ in H₂/He mixture and achieve the purpose of purifying He, the adsorption performance and adsorption mechanism of H₂, He and H₂/He mixture on M-MOF-74 (M=Mg, Co, Ni, Cu, Zn) were studied by molecular simulation. The results show that the selectivity of pure H₂ to pure He on Ni-MOF-74 is 6.58 under the conditions of 1 bar pressure and 25 °C. The amount of H₂ adsorbed on Mg-MOF-74 is the largest (0.19 mmol·cm^-3) in the same condition, which is 6.46 times of He. When the concentration of the H₂/He mixture was changed, it had no great effect on its adsorption separation factor on M-MOF-74, indicating that the concentration change would not affect the ability of the adsorption sites on M-MOF-74 to accommodate H₂ and He. The adsorption site and adsorption heat analysis showed that the metal ion unsaturated sites on MOF-74 could significantly enhance its adsorption capacity for H₂. The results provide a theoretical basis for judging whether M-MOF-74 has the potential to separate H₂/He mixtures and quantitatively analyzing the contribution of metal unsaturated sites of MOFs to the separation of H₂/He mixtures.