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Efficient Adsorption of Super Greenhouse Gas (Tetrafluoromethane) in Carbon Nanotubes

机译:碳纳米管中超级温室气体(四氟甲烷)的高效吸附

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摘要

Light membranes composed of single-walled carbon nanotubes (SWNTs) can serve as efficient nanoscale vessels for encapsulation of tetrafluoromethane at 300 K and operating external pressure of 1 bar. We use grand canonical Monte Carlo simulation for modeling of CF_4 encapsulation at 300 K and pressures up to 2 bar. We find that the amount of adsorbed CF_4 strongly depends on the pore size in nanotubes; at 1 bar the most efficient nanotubes for volumetric storage have size R = 0.68 nm.This size corresponds to the (10,10) armchair nanotubes produced nowadays in large quantities. For mass storage (i.e., weight %) the most efficient nanotubes have size R = 1.02 nm corresponding to (15,15) armchair nanotubes. They are better adsorbents than currently used activated carbons and zeolites, reaching ≈2.4mol kg~(-1) of CF_4, whereas, the bestactivated carbon Carbosieve G molecular sieve can adsorb 1.7 mol kg~(-1) of CF_4 at 300 K and 1 bar. We demonstrate that the high enthalpy of adsorption cannot be used as an only measure of storage efficiency. The optimal balance between the binding energy (i.e., enthalpy of adsorption) and space available for the accommodation of molecules (i.e., presence of inaccessible pore volume) is a key for encapsulation of van der Walls molecules. Our systematic computational study gives the clear direction in the timely problem of control emission of CF4 and other perfluorocarbons into atmosphere.
机译:由单壁碳纳米管(SWNT)组成的轻膜可作为有效的纳米级容器,用于在300 K和1 bar的外部压力下封装四氟甲烷。我们使用经典的蒙特卡洛模拟法对300 K和最高2 bar的压力下的CF_4封装进行建模。我们发现,CF_4的吸附量强烈取决于纳米管的孔径。在1 bar压力下,用于容积存储的最有效的纳米管的尺寸R = 0.68 nm。该尺寸对应于当今大量生产的(10,10)扶手椅状纳米管。对于大容量存储(即重量%),最有效的纳米管的尺寸R = 1.02nm,对应于(15,15)个扶手椅状纳米管。与目前使用的活性炭和沸石相比,它们是更好的吸附剂,达到CF_4的≈2.4molkg〜(-1),而在300 K时,最佳活化碳Carbosieve G分子筛可以吸附1.7 mol kg〜(-1)CF_4。 1巴我们证明了高的吸附焓不能用作存储效率的唯一度量。结合能(即吸附焓)和可用于容纳分子的空间(即存在不可接近的孔体积)之间的最佳平衡是包封范德华分子的关键。我们的系统计算研究为及时控制CF4和其他全氟化碳向大气中的排放提供了明确的方向。

著录项

  • 来源
    《Environmental Science & Technology》 |2008年第8期|p.2931-2936|共6页
  • 作者

    PIOTR KOWALCZYK; ROBERT HOLYST;

  • 作者单位

    Applied Physics, RMIT University, GPO Box 2476V, Victoria 3001, Australia;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 环境化学;
  • 关键词

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