College of Chemistry and Chemical Engineering,Xil'an University of Science and Technology

为给煤层气中甲烷与氮气的变压吸附分离提供相关的模型和热力学数据,采用静态体积法测试了温度298.15、313.15、328.15 K时,CH4/N2在自制炭分子筛上的吸附量,使用Langmuir等9个吸附模型对吸附量进行了非线性拟合,通过比较各吸附模型的拟合精度,得出最优化体积填充模型DA拟合效果最好,经验方程Freundlich模型拟合效果最差,Langmuir、Sips和Toth等模型拟合效果适中,同种模型对于N2的拟合程度好于CH4。同时对各模型的拟合参数进行了分析,BET方程不适合描述CH4、N2在该炭分子筛上的吸附,Langmuir、Toth、E-L等模型中饱和吸附量qm均随温度的升高而减小,且温度变化对于N2的饱和吸附量影响较大;E-L模型、Toth模型和Sips模型中反映吸附剂表面能量不均匀性的参数n随着温度的升高而增大,F-L模型中分形维数D的增大表明温度升高增加了炭分子筛表面不均一性。吸附热力学分析表明,该炭分子筛对于CH4、N2的平均等量吸附热分别为11.80、9.06 k J/mol,均属于物理吸附;随着吸附量的增大,N2的等量吸附热变化范围大于CH4。

in orderto provide the reative adsorption model and thermodynamic data for the separation of CHialNvg in coalbed nethane by pressure swing absoption.the adsorption capaities of CH4 and Ng on the caroon molecular sive(CMS) by sef made at 298.15,313.15 and 328.15 K were measured respectively TheLangnuir model and other eight models were used to ft the experimental data. The fiting degree of these models was compared.Tthe optinizaton volume .ing based model D-A had the best fiting effect while emprical equation Freundich model vas the worst.The fting efect of angmouit Sips and Toh models vere moderte.Th fting de:ree of CH a was beter tnan that of Ny for the same model Meanwile th fitng parameters of diferent models were comparec.the resuls showed that BET model wasuiht o characterze adsopion of CHi; and Nvg on ths CMS. The saturated adsoption capacity qmwas decreased with the inrease of temperature for Langmuir Toth and E-L models.And that change of temperature had greater infuence on Nyg saturated adsorption capacity.The parameter n represened surface energy inhonogeneity of adsorobent increased with the temperature increasing for E-., oth and Sips modes .The increacemen of racal dimension D in F-L model showed higher temperature ncreased CMS surace inhomogeneityThrough the analysis of the adsopion thermodynamics,the average soster c eat ofCH e adsoption was 1.80 k J/ mol which was comparable to 9.06 k J / mol ofNg.the adsoption of CHt and Ng on this CMS were belong to physical aosorption.Wih the increase of asoptonthe isoster e heat range of N2 was larger than that of CH4.

国家科技重大专项资助项目(2011ZX05037-003)；