化学学报 ›› 2013, Vol. 71 ›› Issue (06): 920-928.DOI: 10.6023/A13010126 上一篇    下一篇

研究论文

互穿结构及混合配体对金属-有机骨架材料分离性能的影响

刘蓓, 唐李兴, 廉源会, 李智, 孙长宇, 陈光进   

  1. 中国石油大学(北京)重质油国家重点实验室 北京 102249
  • 收稿日期:2013-01-25 出版日期:2013-06-14 发布日期:2013-04-12
  • 通讯作者: 刘蓓,liub@cup.edu.cn E-mail:liub@cup.edu.cn
  • 基金资助:

    项目受国家自然科学基金(Nos. 21006126, 21276272)、中国石油大学(北京)青年拔尖人才专项基金(BJBJRC-2010-01)、北京市科技新星计划(2010B069)和博士点基金新教师课题(20100007120009)资助.

Study on Separation Performance of Metal-organic Frameworks with Interpenetration and Mixed-ligand

Liu Bei, Tang Lixing, Lian Yuanhui, Li Zhi, Sun Changyu, Chen Guangjin   

  1. State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249
  • Received:2013-01-25 Online:2013-06-14 Published:2013-04-12
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Nos. 21006126, 21276272), the Research Funds of China University of Petroleum, Beijing (BJBJRC-2010-01), Beijing Nova Program (2010B069), and the Research Fund for the Doctoral Program of Higher Education (20100007120009).

在以前的工作中, 我们利用蒙特卡洛和分子动力学模拟计算了具有互穿性结构及混合配体的金属-有机骨架材料(metal-organic frameworks, MOFs)分离CH4/H2的吸附选择性及扩散选择性. 研究了材料的互穿结构及混合配体对材料用于分离CH4/H2性能的影响. 在本工作中, 我们将以前的工作进行了扩展, 详细研究了材料的互穿结构及混合配体对材料用于分离CO2/CH4, CO2/N2和CO2/H2等含有CO2的气体混合物性能的影响. 此外, 为了进一步阐明材料的结构对于其分离性能的影响, 我们亦研究了材料用于分离CH4/H2及CH4/N2. 从我们的结果可以看出, 相比无互穿结构的MOFs材料, 具有互穿结构的MOFs材料对所研究的所有混合气体的渗透选择性明显提高. 这是因为具有互穿结构的MOFs材料对混合气体的吸附选择性明显高于无互穿结构的MOFs材料. 结果表明, 如果将材料作为膜用于气体混合物分离, 使材料产生互穿结构是提高材料分离性能的一个很好的策略.

关键词: 吸附分离, 气体扩散, 膜分离, 金属-有机骨架材料, 分子模拟

In our previous work, we have investigated the adsorption selectivity and diffusion selectivity of CH4/H2 in mixed-ligand interpenetrated metal-organic frameworks (MOFs) to investigate the effects of interpenetration as well as mixed-ligand on both equilibrium-based and kinetic-based gas mixture separation through Monte Carlo and molecular dynamics simulations. The potential of this kind of materials in equilibrium-based and kinetic-based separation applications was evaluated. In this work, we extend our previous work to CO2-related mixtures, like CO2/CH4, CO2/N2, and CO2/H2, as there is an urgent need to identify porous materials that can efficiently separate CO2 from mixtures of gases, such as flue gas and natural gas purification. To show a clearer correlation between gas mixture separation ability and material properties, CH4/H2 and CH4/N2 were also selected as the model mixtures to separate. A combined Monte Carlo and molecular dynamics simulation was carried out in eight MOFs with mixed-ligand and with or without interpenetration. Grand-canonical Monte Carlo (GCMC) simulations were employed to calculate the adsorption of mixtures in MOFs studied. Equilibrium molecular dynamics (MD) simulations were carried out in the canonical (NVT) ensemble to investigate the effects of interpenetration on the diffusion behaviors of mixtures. The adsorption selectivities of mixtures in the selected MOFs were studied in detail. In addition, the diffusion, the permeation selectivities of CH4/H2, CH4/N2, CO2/N2, and CO2/CH4 as well as the CH4 and CO2 permeability through the selected MOF membranes were calculated. We found for all mixtures studied, the permeation selectivities in the interpenetrated MOFs are much higher than those in their non-interpenetrated counterparts due to the larger adsorption selectivities in the former, indicating that interpenetration is a good strategy to improve the overall performance of a material as a membrane in separation applications. The knowledge obtained is expected to serve as the guidance for the development of appropriate interpenetrated MOF adsorbents and membranes.

Key words: adsorption separation, gas diffusion, membrane-based separation, metal-organic frameworks, molecular simulation