ZIF-8吸附剂上CH4/N2的吸附分离性能与热力学性质

将沸石咪唑酯骨架结构材料应用于抽放煤层甲烷的浓缩净化研究。以三乙胺(TEA)为导向剂,ZnSO₄为金属离子源,水为溶剂,采用水热合成法进行了ZIF-8吸附剂的制备。采用XRD、物理吸附、动态吸附分离和反相气相色谱(IGC)等方法对ZIF-8的物理结构、化学稳定性、吸附分离性能和热力学性质进行了研究。结果表明,ZIF-8具有良好的化学稳定性,能够在强酸、强碱和强极性的溶剂中保持结构的稳定性;在298 K时,ZIF-8对CH₄/N₂的分离因子达到3.4,与活性炭相当,但CH₄、N₂在ZIF-8上的吸附热比在活性炭上低20%左右。

Separation of CH4/N2 on ZIF-8 adsorbent and its thermodynamic properties

With triethylamine (TEA) as structure directing agent, ZnSO₄ as metal ion source and water as the solvent, zeolitic imidazolate framework-8 (ZIF-8) adsorbent was prepared by hydrothermal synthesis and used in the separation and enrichment of exhausted coal-bed methane. XRD, physical adsorption, dynamic adsorption equilibrium and inverse gas chromatography (IGC) methods were employed to characterize the physical structure, chemical stability, adsorption and separation performance of the ZIF-8 adsorbent; the adsorption thermodynamics of CH₄ and N₂ on it was also considered. The results indicated that ZIF-8 structure is stable in the acid, alkali and strongly polarized solvent. At 298 K, the separation factor of the ZIF-8 adsorbent towards CH₄/N₂ is up to 3.4, which is comparable to activated carbon; however, ZIF-8 should be more promising in practical application, because the adsorption heat over it is about 20% lower than that over activated carbon.