CO2在氨基改性MIL-101(Cr)中吸附的分子模拟
Molecular Simulation for CO2 Adsorption in Amine-Functionalized MIL-101(Cr)
作者单位E-mail
王之婧 南京工业大学化工学院, 材料化学工程国家重点实验室, 南京 210009  
王俊超 南京工业大学化工学院, 材料化学工程国家重点实验室, 南京 210009  
赵行乐 南京工业大学化工学院, 材料化学工程国家重点实验室, 南京 210009  
马正飞 南京工业大学化工学院, 材料化学工程国家重点实验室, 南京 210009 mazf@njtech.edu.cn 
摘要: 采用实验与分子模拟结合的方法研究298 K下CO2在氨基改性得到的MIL-101(Cr)-NH2和MIL-101(Cr)-ED(ED:乙二胺)上的吸附性能。比较MIL-101(Cr)、MIL-101(Cr)-NH2和MIL-101(Cr)-ED的吸附等温线与吸附热的结果,表明采用直接合成改性法得到的MIL-101(Cr)-NH2比采用合成后再改性得到的MIL-101(Cr)-ED有更高的CO2吸附容量。进一步比较密度分布图和径向密度分布曲线,分析CO2在氨基改性MIL-101(Cr)中的吸附位,表明在低压下CO2首先吸附在MIL-101(Cr)微孔的超级四面体中,随着吸附压力的增大逐渐填充到更大的孔中。氨基的存在增加了CO2的吸附位点,使MIL-101(Cr)-NH2具有较高CO2吸附容量;同时MIL-101(Cr)-ED中的ED分子的存在增加了CO2的吸附位点,使MIL-101(Cr)-ED也具有较高CO2吸附容量;但是MIL-101(Cr)-ED中的ED分子占据了MIL-101(Cr)中Cr的吸附位点,使Cr对CO2的吸附强度减弱,同时可吸附位点少于MIL-101(Cr)-NH2,导致其对CO2的吸附容量少于MIL-101(Cr)-NH2
关键词: CO2  金属有机骨架材料  分子模拟  氨基改性  吸附
基金项目: 
Abstract: The adsorption of CO2 in MIL-101(Cr)-NH2 and MIL-101(Cr)-ED (ED:ethylene diamine) obtained by amine-functionalized MIL-101(Cr) at 298 K were investigated by using experimental and molecular simulation method. The adsorption isotherms and the heats of adsorption of MIL-101(Cr), MIL-101(Cr)-NH2 and MIL-101(Cr)-ED were compared and the results showed that MIL-101(Cr)-NH2 obtained by pre-functionalization approach has higher CO2 adsorption capacity than MIL-101(Cr)-ED obtained by post-synthetic modification. Snapshots and radial density functions were further compared to analyze the adsorption sites of CO2 in amine-functionalized MIL-101(Cr) and it was found that adsorption first occurs in the microporous super tetrahedron at low pressures and then in the bigger pores with increasing pressure. The presence of amine groups in MIL-101(Cr)-NH2 increases the adsorption sites of CO2 which results in higher CO2 adsorption capacity. Similarly, the presence of ED molecules in MIL-101(Cr)-ED increases the CO2 adsorption sites, resulting in higher CO2 adsorption capacity. However, the adsorption strength of Cr to CO2 is weaken by ED molecules since they occupy the Cr adsorption sites. Furthermore, the adsorption sites of MIL-101(Cr)-ED are less than that of MIL-101(Cr)-NH2. Therefore, MIL-101(Cr)-ED has lower CO2 adsorption capacity than MIL-101(Cr)-NH2.
Keywords: CO2  metal-organic frameworks  molecular simulation  amine-functionalized  adsorption
投稿时间:2018-05-30 修订日期:2018-09-07
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王之婧,王俊超,赵行乐,马正飞.CO2在氨基改性MIL-101(Cr)中吸附的分子模拟[J].无机化学学报,2018,34(11):1966-1974.
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