A type of carbon molecular sieve (CMS-3KT) was used as the adsorbent for the CH₄ enrichment of a methane/oxygen/nitrogen (CH₄/O₂/N₂) mixture using micro-positive pressure vacuum pressure swing adsorption (∼120 kPa). The adsorption isotherms of individual CH₄, O₂, and N₂ on CMS-3KT were studied and fitted. The results indicated the important influence of the adsorbent surface heterogeneity on the adsorption equilibrium process. In addition, the interaction of adsorbent–adsorbate in this process was studied from the measured adsorption heat. The adsorption uptake curves were fitted linearly with a classical micropore model for evaluating the kinetics-based separation possibility of CH₄/O₂/N₂, and the corresponding diffusion time constants of CH₄, O₂, and N₂ were calculated. Based on the results of adsorption equilibrium and kinetics, breakthrough experiments were employed to explore the upper limit value of methane concentration in feed gas such that methane can be enriched feasibly but difficultly. The breakthrough experiments were performed on the CH₄/O₂/N₂ mixture with CH₄ concentration ranging from 1 to 30%. Regarding industrial application, the O₂ removal and CH₄ enrichment performance of ultra-low-concentration methane (CH₄ < 5%) were evaluated according to the results of the breakthrough experiment. The results indicated that the proposed method was promising for enriching O₂-containing ultra-low-concentration CBM.

中文翻译：

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以CMS-3KT为吸附剂富氧低浓度煤层气

A型碳分子筛（CMS-3KT）用作吸附剂为CH ₄甲烷/氧/氮的富集（CH ₄ / O ₂ / N ₂）的混合物使用微正压的真空变压吸附（〜 120 kPa）。各个CH ₄，O ₂和N ₂的吸附等温线在CMS-3KT上进行了研究和安装。结果表明，吸附剂表面非均质性对吸附平衡过程具有重要影响。此外，还通过测得的吸附热研究了吸附剂与被吸附物在此过程中的相互作用。用经典的微孔模型对吸附吸收曲线进行线性拟合，以评估基于动力学的CH ₄ / O ₂ / N ₂分离可能性以及相应的CH ₄，O ₂和N ₂扩散时间常数。被计算了。基于吸附平衡和动力学的结果，采用突破性实验来探索进料气中甲烷浓度的上限值，从而使甲烷能够可行而难以富集。对CH ₄ / O ₂ / N ₂混合物的CH ₄浓度范围为1％至30％进行了突破性实验。在工业应用方面，根据突破性实验的结果，对超低浓度甲烷（CH ₄ <5％）的O ₂去除和CH ₄富集性能进行了评估。结果表明，该方法对富集O ₂具有良好的前景。含超低浓度煤层气。