CH4-N2在自支撑颗粒型Silicalite-1上的吸附分离及PSA模拟

纯硅分子筛Silicalite-1原粉（Si/Al>470）在6 MPa压力下制成自支撑颗粒状吸附剂，经XRD和77 K氮气吸脱附表征表明自支撑颗粒型的Silicalite-1保留了原粉的晶体结构和比表面。静态重量法测试了273/298/313 K下CH₄和N₂在其上的吸附等温线，利用理想吸附溶液理论（IAST）法计算了吸附剂对CH₄/N₂的选择性。动态气体穿透实验测试了颗粒型Silicalite-1吸附剂对不同浓度CH₄/N₂混合气的分离效果，结果表明该吸附剂更适合于低浓度甲烷（20%/80% CH₄/N₂）的富集脱氮。通过总传质模型利用数值模拟预测了颗粒型Silicalite-1吸附剂的变压吸附分离（PSA）富集低浓度煤层气中甲烷的效果。模拟结果显示20%/80%的CH₄/N₂混合气经一次提浓，CH₄浓度可以提升至37%~41%，回收率达到60%~92%；30%/70%的CH₄/N₂混合气经一次提浓，CH₄浓度可以提升至50%~53%，回收率达到58%~92%。

PSA simulation and adsorption separation of CH4-N2 by self-supporting pellets Silicalite-1

Pure-silica zeolite Silicalite-1 powder was pressed at 6 MPa pressure to form self-supporting pellets. By characterization of powder X-ray diffraction and 77 K nitrogen adsorption-desorption, there was no change in crystalline and specific surface area after pelletization. Single component adsorption equilibrium isotherm of CH₄ and N₂ on the self-supporting pellets Silicalite-1 at 273/298/313 K were measured by static gravimetric method. Selectivity of CH₄/N₂ mixtures on the adsorbent were calculated from Ideal Adsorbed Solution Theory (IAST). Separation effects of CH₄/N₂ mixtures on the adsorbent were investigated by dynamic mixtures breakthrough experiments, which show it is more suitable for enrichment and nitrogen removal from low concentration coal-bed methane. Separation and enrichment of methane from low concentration coal-bed methane by pressure swing adsorption (PSA) on the particle-shaped Silicalite-1 were predicted using total mass-transfer model by numerical simulation based on abovementioned data. The simulation results show that once the 20% / 80% CH₄ / N₂ mixture is concentrated, the CH₄ concentration can be increased to 37%—41%, and the recovery rate can be 60%—92%; 30%/70% CH₄/N₂ mixture is once concentration, CH₄ concentration can be increased to 50%—53%, and the recovery rate is 58%—92%.