用水合物储存氧气的计算化学模拟研究

Computational Chemistry Modeling of the Oxygen Storage in Clathrate Hydrates

关键词:  水合物储氧  清洁能源  量子化学  逃逸势垒  储存密度

Key words:  oxygen-hydrate clathrate  clean energy  quantum chemistry  escaping barrier  storing density

摘要:

[目的]用水合物在常温常压下能够储存氧气,在清洁能源、军事、航天、环境和生态保护等方面都有重大潜在应用,本文主要探讨水合物储氧的最佳比例和稳定性。[方法]在由20个水分子组成的正十二面体水合物5¹²结构单元中分别放置1~3个氧分子,用量子化学方法优化氧分子簇(O₂,2O₂,3O₂)与水合物5¹²结构单元的作用结构,并计算水合物稳定能。[结果]在边长为2.82Å的水合物5¹²结构单元中放置1个和2个氧分子时得到吸引的稳定能;当储存3个氧分子时水合物单元与氧分子簇间的稳定能转为排斥。[结论]当边长为2.82Å时,在水合物5¹²结构单元中最多可以存储2个氧分子。氧分子从水合物5¹²结构单元中逃逸的势垒高达~200 kJ/mol,远高于氢分子的逃逸势垒~80 kJ/mol。

Abstract:

[Objective] Storage of oxygen molecules (O₂) in clathrate hydrate at ambirent condition has many potential applications, such as clean energy, environment and ecology protection, shuttle, space rocket, submarine and so on.[Methods] The clathrate hydrate of oxygen molecules is studied by using quantum chemical methods Hartree-Fock, B3LYP and MP2.[Results] When 1 or 2 oxygen molecules are included in the 5¹² hydrate cell with side length 2.82Å, the stable energy is atractive.When 3 oxygen molecules are trapped in the 5¹² cell, the stable energy turns to repulsive.[Conclusion] When the side length is 2.82Å, at most 2 oxygen molecules can be stored in a 5¹² hydrate cell.The escaping energy barrier of oxygen molecule is 200 kJ/mol, which is much higher than the escaping energy barrier 74 kJ/mol of hydrogen molecules.