CO/N2/CO2在MOF-74(Ni)上吸附相平衡和选择性

主要研究了MOF-74(Ni)材料对CO/N₂/CO₂的吸附分离性能。应用水热法合成制备MOF-74(Ni),分别采用全自动表面积吸附仪、P-XRD、扫描电子显微镜对材料的孔隙结构和晶体形貌进行了表征,应用静态吸附法测定了CO、N₂和CO₂在MOF-74(Ni)上的吸附等温线,应用DSLF方程模拟了3种气体MOF-74(Ni)上的吸附等温线,依据IAST理论模型计算了MOF-74(Ni)对CO/N₂二元混合物和CO/CO₂二元混合物的吸附选择性。研究结果表明:在0.1 MPa和常温条件下,MOF-74(Ni)材料对CO吸附容量高达6.15 mmol·g^-1,而相同条件下N₂的吸附量只有0.86 mmol·g^-1。MOF-74(Ni)在低压下(0～40 kPa)对CO的吸附量明显高于其对CO₂的吸附量。应用IAST模型估算MOF-74(Ni)对二元混合物吸附选择性的结果表明:MOF-74(Ni)对CO/N₂混合物的吸附选择性在1000以上;MOF-74(Ni)对CO/CO₂的吸附选择性在4～9范围,在所研究的二元气体混合物吸附体系中,MOF-74(Ni)都能优先吸附CO。

Adsorption isotherms and selectivity of CO/N2/CO2 on MOF-74(Ni)

This work investigates the adsorption performance of adsorbent MOF-74(Ni) for CO/N₂ and CO₂/CO₂ binary gas mixtures. Adsorbent MOF-74(Ni) with high density of coordinatively unsaturated sites was synthesized by a hydrothermal method, and characterized with N₂ adsorption, P-XRD, and SEM. The adsorption isotherms of CO, N₂ and CO₂ on MOF-74(Ni) were measured, and the selectivities for CO/N₂ and CO/CO₂ were calculated based on ideal adsorbed solution theory (IAST). Results showed that adsorbent MOF-74(Ni) achieved superior CO adsorption capacity of 6.15 mmol·g^-1 at 298 K and 0.1 MPa, and as low as 0.86 mmol·g^-1 for N₂. In low pressure range of 0-40 kPa, MOF-74(Ni) showed significantly higher uptake for CO than that for CO₂. Moreover, IAST-predicted CO/N₂ selectivity of MOF-74(Ni) is above 1000, and its CO/CO₂ selectivity is in the range of 4-9. It suggests that MOF-74(Ni) is more favorable for CO adsorption than N₂ and CO₂ adsorption.