The adsorption separation of CO_2, CH_4 and N_2 was studied via volumetric measurements of t3-zeolite samples with different SiO_2/Al_2O_3 ratios at 273 and 303 K. Results showed that all the obtained adsorption isotherms are well correlated with the Langmuir-Freundlich model. For a certain sample, the adsorption capacity for CO_2 is much higher than that for CH_4 and N_2. The adsorption capacity for CO_2 increases with the decrease in SiO_2/Al_2O_3 ratio under same temperature and pressure. The Henry law's constant and adsorption equilibrium selectivity of CO_2, CH_4, and N_2 on different β-zeolite samples were calculated via Virial equation, showing that the β-zeolite samples have higher equilibrium selectivity for CO_2 over N_2 and CH_4. The selectivity of CO_2 over N_2 and CH_4 increases with the decrease in SiO_2/Al_2O_3 ratio. Therefore, the β-zeolite sample with a low SiO_2/Al_2O_3 ratio is a good candidate for the separation of carbon dioxide from its mixture with methane and nitrogen. The isosteric adsorption heat for CO_2, CH_4 and N_2 calculated by Clausius-Clapeyron equation is independent with the increase of adsorption loading, which indicates that β-zeolite is an energetically homogenous adsorbent.%采用体积法在273 K和303 K温度下对CO_2,CH_4和N_2在不同硅/铝比的β沸石上的吸附分离性能进行了研究.实验结果表明,Langmuir-Freundlich模型能够较好地拟合吸附实验数据;同一样品上,CO_2的吸附量要大于CH_4和N_2的吸附量;随着硅铝比的减小CO_2的吸附量增加,而硅/铝比对CH_4和N_2的吸附量的影响较小.通过结合Virial方程计算CO_2、CH_4和N_2在不同硅/铝比β沸石上的亨利定律常数和吸附选择性,发现所研究样品对CO_2/CH_4和CO_2/N_2均具有很高的吸附选择性,随着样品硅/铝比的减小,CO_2/CH_4和CO_2/N_2的吸附选择性显著增加,说明较低硅/铝比β沸石有利于分离CO_2.用Clausius-Ciapeyron方程求得CO_2,CH_4和N_2在不同硅/铝比的β沸石上的吸附热与吸附量无关,表明β沸石是一种表面势场均匀的吸附剂.
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