斜发沸石的水热合成和离子交换性能及其在CH4/N2分离中的应用

以氢氧化铝为铝源，硅溶胶为硅源，通过水热法合成斜发沸石，采用XRD、TEM、BET、FT IR、TG、29Si NMR 等手段考察了OH-/Si的摩尔比、晶化时间和晶化温度等合成参数对其结构和CH4/N2分离性能的影响。基于晶化动力学曲线，由阿伦尼乌斯方程导出诱导期和生长阶段的表观活化能值，分别为915和72 kJ/mol。通过水溶液离子交换工艺分别获得Ca型或K型斜发沸石，并初步探讨了离子交换前后斜发沸石对CH4/N2的分离性能。结果表明，斜发沸石对CH4/N2的平衡选择性依赖于交换阳离子电荷类型，数量及其在骨架中的分布，其中K型斜发沸石分离效果较好，有望用于煤层气回收。

Hydrothermal Synthesis of Clinoptilolite and its Ion Exchange Performancefor CH4/N2 Separation

Clinoptilolite was synthesized via hydrothermal method using aluminum hydroxide as aluminum source and silica sol (Ludox) as silicon source. The influences of synthesized parameters (ie, molar ratio of  n(OH-)/n(Si), crystallization time and crystallization temperature, etc.) on the structure of prepared clinoptilolite and its CH4/N2 separation performance were investigated by various characterization techniques, including XRD, TEM, BET, FT IR, TG, 29Si NMR. Particularly, the kinetic behaviors of crystallization rate were evaluated, and the apparent activation energies for induction and growth period according to Arrhenius equation are 915 and 72 kJ/mol, respectively. Meanwhile, Ca2+ and K+ clinoptilolites were prepared through water solution ion exchange method. Moreover, the CH4/N2 separation performance was also evaluated for clinoptilolites with/without ion exchange. Experimental results suggest that equilibrium selectivity of CH4/N2 is strongly depended on the type of exchanged cationic charge, its quantity and distribution in the skeleton. K clinoptilolite exhibited a good separation performance, and could be a promising absorbent for coal bed methane recovery.