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...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N_2的拟合程度好于CH_4。同时对各模型的拟合参数进行了分析,BET方程不适合描述CH_4、N_2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N_2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CH_4、N_2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,N_2的等量吸附热变化范围大于CH_4。展开更多
The performance of various types of zeolites for N2/O2 and CH4/N2 separation has been studied. The separation factors αN2/O2 and αCH4/N,2 for all the Na-form zeolites are < 1. Compared with Na-form zeolites, H-fo...The performance of various types of zeolites for N2/O2 and CH4/N2 separation has been studied. The separation factors αN2/O2 and αCH4/N,2 for all the Na-form zeolites are < 1. Compared with Na-form zeolites, H-form zeolites adsorb larger quantities of O2 and smaller quantities of N2, so αN2/O2 is increased, but αCH4/N2 is reduced. On the contrast, Ca-form zeolites adsorb larger quantities of N2, so αN2/O2 is reduced but αCH4/N2 is increased. However the αN2/O2 and αCH4/N2 for both H- and Ca- form zeolites are <1. The changes in adsorption behavior can be explained in the light of energetics of sorption in zeolites. Chemical vapor deposition with silicon methoxide has been used to control the pore-opening size of the zeolites. As the amount of SiO2 deposition on NaA is increased, the adsorption of the bulkier component in the binary gas mixture is suppressed, so the values of αN2/O2 and αCH4/N2 for SiNaA zeolites are increased qulckly to>1. Experimental results show that if the right type of zeolite is chosen fine control of zeollte pore-opening size through chemical vapor deposition has a potential as a good method for preparing high selective adsorbent in gas separation.展开更多
文摘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N_2的拟合程度好于CH_4。同时对各模型的拟合参数进行了分析,BET方程不适合描述CH_4、N_2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N_2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CH_4、N_2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,N_2的等量吸附热变化范围大于CH_4。
文摘The performance of various types of zeolites for N2/O2 and CH4/N2 separation has been studied. The separation factors αN2/O2 and αCH4/N,2 for all the Na-form zeolites are < 1. Compared with Na-form zeolites, H-form zeolites adsorb larger quantities of O2 and smaller quantities of N2, so αN2/O2 is increased, but αCH4/N2 is reduced. On the contrast, Ca-form zeolites adsorb larger quantities of N2, so αN2/O2 is reduced but αCH4/N2 is increased. However the αN2/O2 and αCH4/N2 for both H- and Ca- form zeolites are <1. The changes in adsorption behavior can be explained in the light of energetics of sorption in zeolites. Chemical vapor deposition with silicon methoxide has been used to control the pore-opening size of the zeolites. As the amount of SiO2 deposition on NaA is increased, the adsorption of the bulkier component in the binary gas mixture is suppressed, so the values of αN2/O2 and αCH4/N2 for SiNaA zeolites are increased qulckly to>1. Experimental results show that if the right type of zeolite is chosen fine control of zeollte pore-opening size through chemical vapor deposition has a potential as a good method for preparing high selective adsorbent in gas separation.
