物理化学学报 >> 2015, Vol. 31 >> Issue (2): 261261-267.doi: 10.3866/PKU.WHXB201411271

理论与计算化学 上一篇    下一篇

多孔石墨烯分离CH4/CO2的分子动力学模拟

温伯尧, 孙成珍, 白博峰   

  1. 西安交通大学动力工程多相流国家重点实验室, 西安 710049
  • 收稿日期:2014-09-29 修回日期:2014-11-26 发布日期:2015-01-26
  • 通讯作者: 白博峰 E-mail:bfbai@mail.xjtu.edu.cn
  • 基金资助:

    国家自然科学基金创新群体(51121092)和国家杰出青年科学基金(51425603)资助项目

Molecular Dynamics Simulation of the Separation of CH4/CO2 by Nanoporous Graphene

WEN Bo-Yao, SUN Cheng-Zhen, BAI Bo-Feng   

  1. State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049, P. R. China
  • Received:2014-09-29 Revised:2014-11-26 Published:2015-01-26
  • Contact: BAI Bo-Feng E-mail:bfbai@mail.xjtu.edu.cn
  • Supported by:

    The project was supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (51121092) and National Funds for Distinguished Young Scientists, China (51425603).

摘要:

采用分子动力学方法模拟CH4/CO2混合气体在多孔石墨烯分离膜中的分离过程, 分析了3 种纳米孔功能化修饰(N/H 修饰、全H修饰和N/―CH3修饰)对分离过程的影响规律. 模拟结果表明气体分子会在石墨烯表面形成吸附层, CO2分子的吸附强度高于CH4分子. 纳米孔的功能化修饰不仅减小了纳米孔的可渗透面积, 还通过影响纳米孔边缘原子的电荷分布提高了气体分子的吸附强度, 进而影响了混合气体分子在多孔石墨烯分离膜中的渗透性和选择性. CO2分子在多孔石墨烯中的渗透率能达到106 GPU (1 GPU=3.35×10-10 mol·s-1·m-2·Pa-1), 远远高于传统的聚合物分离膜. 研究表明多孔石墨烯分离膜在天然气处理、CO2捕获等工业气体分离过程中具有广泛的应用前景.

关键词: 多孔石墨烯, 分离膜, 分子动力学, 功能化修饰

Abstract:

The processes involved in the separation of gaseous CH4/CO2 mixtures using a nanoporous graphene membrane were simulated using a molecular dynamics method, and the effects of three functional modifications (i.e., N/H, all H, and N/―CH3 modifications) in the nanopores were analyzed. The results showed that the gas molecules could form an adsorption layer on the surface of the graphene. The adsorption intensity of the CO2 molecules was higher than that of the CH4 molecules. The functional modifications in the nanopores not only reduced the permeable area, but also improved the adsorption intensity of the gas molecules by changing the potential distribution of atoms at the edge of nanopores, and therefore affecting the permeability and selectivity of the gas mixture being separated by the nanoporous graphene membranes. Furthermore, the permeability of the CO2 molecules was as high as 106 GPU (1 GPU=3.35×10-10 mol·s-1·m-2·Pa-1), which was far greater than those of the existing polymer gas separation membranes. These results therefore demonstrate that nanoporous graphene membranes could be used in an extensive range of applications in industrial gas separation processes, such as natural gas processing and CO2 capture.

Key words: Nanoporous graphene, Separation membrane, Molecular dynamics, Functional modification

MSC2000: 

  • O647