摘要
构建了氨基修饰微孔/介孔复合材料AM-5A-MCM-41的全原子模型,采用巨正则Monte Carlo(GCMC)方法研究了它的CO2吸附分离性能,采用加权混合规则来描述氨基和CO2分子的弱化学作用。模拟结果表明,CO2分子优先吸附在复合材料介孔表面的氨基附近,CO2纯气体的吸附量和吸附热有了显著提高,而N2的吸附量和吸附热则基本不受影响。对于CO2和N2的混合气分离,由于复合材料对CO2的弱化学吸附作用,显著提高了CO2吸附量和吸附选择性,在573 K和100 kPa时CO2/N2的选择性达到了87.0。通过分子模拟研究可以从微观角度了解CO2在氨基修饰的微孔/介孔复合材料中的吸附分离的细节和机理,为实验设计和合成高效CO2吸附剂提供指导。
Combining the advantages of high selectivity of amine groups, high capacity of microporous zeolite, and high transportation of mesoporous structures, amine modified micro/mesoporous composites may exhibit promising CO2 adsorption capability. In this study, a full-atomic mimetic amine modified micro/mesoporous composite of AM-5A-MCM-41 was constructed. CO2 adsorption and separation performance on AM-5A- MCM-41 composite were investigated by the grand canonical Monte Carlo （GCMC）, in which a specific combining rule was used to describe the weak chemical interaction between CO2 molecule and amine group. The simulation results demonstrate that CO2 is preferentially adsorbed around amine groups, which is grafted at the surface of mesoporous channels; and the CO2 adsorption capacity and its isosteric heat are greatly improved on AM-5A-MCM-41, whereas those of N2 are almost kept unchanged. For the separation of mixed gas of CO2 and N2, both CO2 adsorption capacity and CO2/N2 selectivity are greatly improved, due to the enhanced interaction between CO2 molecules and amine groups. The chemisorption plays a significant role in the capture of CO2 at low＆amp;nbsp;pressures and high temperature, giving a selectivity as high as 87.0 at 573 K and 100 kPa. The overall results show that molecular simulations serve as a powerful implement to assist the design and development of new promising CO2 adsorbents, highlighting the importance of this approach.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2014年第5期1680-1687,共8页
CIESC Journal
基金
国家重点基础研究发展计划项目(2013CB733501)
国家自然科学基金项目(21176066
91334203)
中央高校基本科研业务费专项资金~~
关键词
分子模拟
二氧化碳吸附
氨基修饰
微孔
介孔材料
选择性
molecular simulation
CO2 adsorption
amine modification
micro/mesoporous
selectivity
