CH_4/CO_2在MIL-101上的吸附相平衡及选择性  

Phase Balance and Selectivity of CH_4/ CO_2 Adsorption on MIL-101

作　　者：夏启斌[1] 苗晋朋 孙雪娇[1] 周欣[1] 李忠[1] 奚红霞[1] 

机构地区：[1]华南理工大学化学与化工学院,广东广州510640

出　　处：《华南理工大学学报（自然科学版）》2013年第12期24-28,42,共6页Journal of South China University of Technology(Natural Science Edition)

基　　金：国家"973"计划项目子课题(2013CB733506);国家自然科学基金资助项目(21276092);广东省科技计划项目(2011B010100030)

摘　　要：采用重量法测定了298、303、308、313 K下CH4、CO2在MIL-101多孔材料上的吸附等温线，估算了MIL-101对CH4、CO2的等量吸附热，并利用DL-IAST模型计算出不同温度下CH4/CO2混合气中各组分的吸附分量，探讨了CO2的吸附选择性．结果表明：298 K、2500 kPa时，CO2在MIL-101上的吸附量为14．51 mmol/g，远高于同等条件下商业活性炭、沸石和分子筛对CO2的吸附容量；CH4、CO2在MIL-101上的吸附等温线与Double-Langmuir模型吻合很好，说明该吸附主要为双孔位吸附；CO2在MIL-101上的等量吸附热在19．3～25．5kJ/mol范围内；与CH4相比，CO2在MIL-101上的表面自由结合能更高；298K、250kPa时，MIL-101对CO2的吸附选择性指数为5．6；随着压力的增大，CO2的吸附选择性逐渐减小；随着混合气中CO2浓度的下降，CO2的吸附选择性上升．In this paper,the adsorption isotherms of CH4 and CO2 on MIL-101 were obtained by means of the gravi-metric method at 298,303,308 and 313 K,and the corresponding isosteric adsorption heat was estimated.Then, the pure gas adsorption was calculated by using the DL-IAST model,and the adsorption selectivity of CO2 on MIL-101 was discussed.The results show that （1）the adsorption capacity of pure CO2 on MIL-101 is up to 14.51 mmol/g at 298 K and 2500 kPa,which is much higher than that on activated carbon,zeolite and molecular sieve under similar conditions;（2）the isotherms of pure CO2 and CH4 well accord with the Double-Langmuir model,which shows the presence of two adsorption sites;（3）the isosteric adsorption heat of CO2 on MIL-101 ranges from 19.3 to 25.5 kJ/mol;（4）as compared with CH4,CO2 is of higher surface free energy for its interaction with the framework of MIL-101;（5）the adsorption selectivity index of CO2 over CH4 on MIL-101 is up to 5.6 at 298 K and 250 kPa;and （6）the adsorption selectivity of CO2 over CH4 gradually decreases with the increase of pressure and the concentration of CO2 in CH4/CO2 mixture.

关 键 词：甲烷 二氧化碳 MIL-101 多孔材料 理想吸附溶液理论 吸附选择性 吸附等温线 

分 类 号：O647.3[理学—物理化学]