SCI和EI收录∣中国化工学会会刊

中国化学工程学报 ›› 2021, Vol. 37 ›› Issue (9): 46-53.DOI: 10.1016/j.cjche.2021.05.001

• Separation Science and Engineering • 上一篇    下一篇

Superior performance porous carbon nitride nanosheets for helium separation from natural gas: Insights from MD and DFT simulations

Zilong Liu1,2, Ge Zhao1, Xiao Zhang1, Lei Gao1, Junqing Chen1, Weichao Sun2, Guanggang Zhou1, Guiwu Lu1   

  1. 1. Beijing Key Laboratory of Optical Detection Technology for Oil and Gas, College of Science, China University of Petroleum (Beijing), Beijing 102249, China;
    2. Nano-Science Center, Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
  • 收稿日期:2021-01-29 修回日期:2021-04-26 出版日期:2021-09-28 发布日期:2021-11-02
  • 通讯作者: Lei Gao, Guiwu Lu
  • 基金资助:
    The authors thank Dr. Xiao Chang, Dr. Xiaofang Li, and Dr. Lei Zhu (China University of Petroleum, Qingdao) for their active discussions and valuable suggestions. The computations were performed on Materials Studio at Shenzhen Supercomputing Center. This work was supported by the Science Foundation of China University of Petroleum, Beijing (2462020BJRC007, 2462020YXZZ003, 2462020BJRC005) and Major Science and Technology Project of Shanxi Province (20181101013, 20201102002).

Superior performance porous carbon nitride nanosheets for helium separation from natural gas: Insights from MD and DFT simulations

Zilong Liu1,2, Ge Zhao1, Xiao Zhang1, Lei Gao1, Junqing Chen1, Weichao Sun2, Guanggang Zhou1, Guiwu Lu1   

  1. 1. Beijing Key Laboratory of Optical Detection Technology for Oil and Gas, College of Science, China University of Petroleum (Beijing), Beijing 102249, China;
    2. Nano-Science Center, Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
  • Received:2021-01-29 Revised:2021-04-26 Online:2021-09-28 Published:2021-11-02
  • Contact: Lei Gao, Guiwu Lu
  • Supported by:
    The authors thank Dr. Xiao Chang, Dr. Xiaofang Li, and Dr. Lei Zhu (China University of Petroleum, Qingdao) for their active discussions and valuable suggestions. The computations were performed on Materials Studio at Shenzhen Supercomputing Center. This work was supported by the Science Foundation of China University of Petroleum, Beijing (2462020BJRC007, 2462020YXZZ003, 2462020BJRC005) and Major Science and Technology Project of Shanxi Province (20181101013, 20201102002).

摘要: Increasing helium (He) demand in fundamental research, medical, and industrial processes necessitates efficient He purification from natural gas. However, most theoretically available membranes focus on the separation of two or three kinds of gas molecules with He and the underlying separation mechanism is not yet well understood. Using molecular dynamic (MD) and first-principle density function theory (DFT) simulations, we systematically demonstrated a novel porous carbon nitride membrane (g-C9N7) with superior performance for He separation from natural gas. The structure of g-C9N7 monolayer was optimized first, and the calculated cohesive energy confirmed its structural stability. Increasing temperature from 200 to 500 K, the g-C9N7 membrane revealed high He permeability, as high as 1.48×107 GPU (gas permeation unit, 1 GPU=3.35×10-10 mol·s-1·Pa-1·m-2) at 298 K, and also exhibited high selectivity for He over other gases (Ar, N2, CO2, CH4, and H2S). Then, the selectivity of He over Ne was found to decrease with increasing the total number of He and Ne molecules, and to increase with increasing He to Ne ratio. More interestingly, a tunable He separation performance can be achieved by introducing strain during membrane separation. Under the condition of 7.5% compressive strain, the g-C9N7 membrane reached the highest He over Ne selectivity of 9.41×102. It can be attributed to the low energy barrier for He, but increased energy barrier for other gases passing through the membrane, which was subject to a compressive strain. These results offer important insights into He purification using g-C9N7 membrane and opened a promising avenue for the screening of industrial grade gas separation with strain engineering.

关键词: Helium separation, g-C9N7 membrane, Selectivity, Permeability, Molecular simulation

Abstract: Increasing helium (He) demand in fundamental research, medical, and industrial processes necessitates efficient He purification from natural gas. However, most theoretically available membranes focus on the separation of two or three kinds of gas molecules with He and the underlying separation mechanism is not yet well understood. Using molecular dynamic (MD) and first-principle density function theory (DFT) simulations, we systematically demonstrated a novel porous carbon nitride membrane (g-C9N7) with superior performance for He separation from natural gas. The structure of g-C9N7 monolayer was optimized first, and the calculated cohesive energy confirmed its structural stability. Increasing temperature from 200 to 500 K, the g-C9N7 membrane revealed high He permeability, as high as 1.48×107 GPU (gas permeation unit, 1 GPU=3.35×10-10 mol·s-1·Pa-1·m-2) at 298 K, and also exhibited high selectivity for He over other gases (Ar, N2, CO2, CH4, and H2S). Then, the selectivity of He over Ne was found to decrease with increasing the total number of He and Ne molecules, and to increase with increasing He to Ne ratio. More interestingly, a tunable He separation performance can be achieved by introducing strain during membrane separation. Under the condition of 7.5% compressive strain, the g-C9N7 membrane reached the highest He over Ne selectivity of 9.41×102. It can be attributed to the low energy barrier for He, but increased energy barrier for other gases passing through the membrane, which was subject to a compressive strain. These results offer important insights into He purification using g-C9N7 membrane and opened a promising avenue for the screening of industrial grade gas separation with strain engineering.

Key words: Helium separation, g-C9N7 membrane, Selectivity, Permeability, Molecular simulation