Simulations of Binary Mixture Adsorption of Carbon Dioxide and Methane in Carbon Nanotubes: Temperature, Pressure, and Pore Size Effects

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• 作者：Liangliang Huang ; Luzheng Zhang ; Qing Shao ; Linghong Lu ; Xiaohua Lu ; Shaoyi Jiang ; Wenfeng Shen
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：August 16, 2007
• 年：2007
• 卷：111
• 期：32
• 页码：11912 - 11920
• 全文大小：304K
• 年卷期：v.111,no.32(August 16, 2007)
• ISSN：1932-7455

文摘

Grand canonical Monte Carlo (GCMC) simulations were performed to investigate the adsorption behavior ofan equimolar CO₂/CH₄ mixture in carbon nanotubes (CNTs). Five CNTs [(6, 6), (7, 7), (8, 8), (9, 9), and (10,10)] with diameters varying from 0.678 to 1.356 nm, seven temperatures (283, 293, 303, 313, 323, 333, 343K), and seven pressures (1, 5, 10, 15, 20, 25, 30 MPa) were chosen to investigate the effect of temperature,pressure, and pore size on the adsorption behavior. The results show that the CNTs have a preferential adsorptionof CO₂ in the binary CO₂/CH₄ mixture. For pore size effect on the adsorption behavior, we found that theadsorption of CO₂ is much larger than that of CH₄ in the same CNT and that the CO₂ adsorption in the CNTsincreases dramatically with an increase of CNT's diameter, whereas the absolute amount of adsorbed CH₄changes little with the CNT's pore size. In the investigated temperature and pressure ranges, we observedthat in the CNTs with diameters less than 1.1 nm, the temperature and pressure have little effect on theadsorption behavior of the binary mixture, whereas in larger CNTs the adsorption behavior changes withtemperature and pressure significantly. In addition, the CNTs demonstrated a higher selectivity of CO₂ thanother materials (activated carbons, zeolites 13X, and metal-organic frameworks) reported in the literature.For example, in (6, 6) CNT at 343 K and 1 MPa, the selectivity reaches 11.2, larger than that reported inactivated carbon. The selectivity in narrow CNTs (<1 nm in diameter) is fluctuating with temperature andpressure, but it remains almost the same in larger CNTs at the investigated temperature and pressure.