Abstract: Adsorption equilibrium of pure methane and ethane on activated carbon 204-Ⅱ was determined by the volumetric method at 293 K and 0-4 MPa.Adsorption data,with the CH₄ concentration in the range of 34.0%-95.2%,were measured by the open flow method on activated carbon 204-Ⅱ at 293 K.The real adsorption solution theory(RAST)expressing the non-ideality of the local adsorbed phase was combined with the micro-pore size distribution(MPSD)model describing the energetic distribution of the adsorbent surface,and a MPSD-RAST model was put forward to predict adsorption equilibrium of binary CH₄-C₂H₆ system.The Wilson equation and the NTRL equation were adopted to calculate activity coefficients for the local adsorbed phase.The ideal adsorption solution theory(IAST)and the MPSD-IAST model were also used for prediction.The investigation demonstrates that the MPSD-RAST model greatly improves prediction accuracy of the adsorption amount and the mole fraction for CH₄,compared with the IAST and MPSD-IAST models.For the heavy component C₂H₆,prediction deviations with these three methods are all lower than 5%.It is important to consider non-ideality of the adsorbed phase in prediction models.

Key words: gas mixture, adsorption equilibrium, adsorbed phase, non-ideality, activity coefficient, model

摘要： 采用容积法测试了纯CH₄和C₂H₆在204-Ⅱ活性炭上的吸附等温线,温度为293 K,压力范围为0～4 MPa。采用捕集法测试了CH₄-C₂H₆混合体系293 K、0～1.1 MPa条件下在204-Ⅱ活性炭上的吸附平衡数据,其中CH₄浓度范围34.0%～95.2%。引入描述吸附相自身非理想性的真实吸附溶液模型(RAST),结合描述吸附剂表面势场不均一的孔径分布模型(MPSD),建立了MPSD-RAST模型,其中RAST模型中的活度因子使用Wilson方程和NTRL方程计算。采用MPSD-RAST模型对CH₄-C₂H₆吸附平衡数据进行了预测,并与理想吸附溶液模型(IAST)和MPSD-IAST模型进行了对比分析。结果表明,对于轻组分CH₄,MPSD-RAST模型预测平衡吸附量和摩尔分数的精度明显优于IAST和MPSD-IAST模型;对于重组分C₂H₆,IAST、MPSD-IAST和MPSD-RAST 3种模型的预测偏差均低于5%。研究结果表明,预测混合气体的吸附平衡,吸附相自身非理想性是必须考虑的重要因素。

关键词: 混合气体, 吸附平衡, 吸附相, 非理想性, 活度因子, 模型