浓凝胶转换法制备纳米SAPO-34及其CH4/N2吸附分离性能研究

通过浓凝胶转换法合成了一种厚度约为50 nm, 大小约为200 nm的纳米片状SAPO-34分子筛, 经XRD, SEM, ICP和氮气(77 K)吸附-脱附等方法对其进行了表征, 结果显示, 相比于微米级立方体形的SAPO-34 (2 μm), 本文合成的纳米片状SAPO-34表现出更高的比表面积(818.68 m²/g)和孔容(0.57 cm³/g). 比表面和孔容积的增大使其气体吸附容量得到较大的提升, 其中CH₄的吸附容量达到25.74 cm³/g, 提升了60%, 高于绝大多数分子筛吸附剂, 同时CH₄/N₂的吸附选择性未出现明显下降(3.1), 且达到商用吸附剂水平(＞3.0). 通过CH₄/N₂(体积比1∶1, 298 K)混合气体穿透测试证明所合成的纳米SAPO-34是一种有效的CH₄/N₂分离吸附剂, 在煤层气富集脱氮工业中具有极大的应用潜力.

Synthesis of Nano-sized SAPO-34 via Concentrated Gel Conversion Method and Its CH4/N2 Separation Performance

Nano-sized SAPO-34 molecular sieve with a thickness of ca. 50 nm was synthesized by concentra- ted gel conversion method. The obtained samples were characterized by means of XRD， SEM， ICP as well as N₂ adsorption-desorption isotherms（77 K）. The results show that the synthesized nano-sized SAPO-34 has higher specific surface area（818.68 m²/g） and pore volume（0.57 cm³/g） compared with the micron cubic SAPO-34（2 μm）. With higher specific surface and pore volume， the adsorption capacity of CH₄ on the nano-sized SAPO-34 is greatly increased（60%）， reaching 25.74 cm³/g， which is higher than most of the commercial zeolite adsorbents. At the same time， the adsorption selectivity of CH₄/N₂ is not significantly decreased（3.1）， and reaches the level of commercial adsorbents（>3.0）. Through CH₄/N₂（volume ratio 1∶1） mixture gas breakthrough test， it is proved that the synthesized nano SAPO-34 is indeed an effective CH₄/N₂ separation adsorbent and has great potential in the industrial application of coalbed methane enrichment and denitrification.