用分子动力学模拟水合物储氢

用分子动力学(MD)模拟方法系统研究了结构Ⅰ型(SⅠ)和结构H型(SH)氢气水合物中氢气的占据情况并确定了氢气水合物的稳定结构: SⅠ水合物氢气分子数小胞中为2, 大胞中为3; SH水合物氢气分子数小胞中为2, 中胞中为2, 大胞中为11. 分析了稳定情况下水合物各胞腔内氢气分子之间的径向分布函数(RDF), 得出了氢气分子在各胞腔内的稳定位置. 由稳定位置得到了稳定结构下氢气水合物的储氢质量分数: SⅠ为5.085%, SH为6.467%. 与实验对比得出结论: SH水合物稳定结构下的储氢能力最强.

Molecular Dynamics Simulation of Storage Hydrogen in Hydrate

The structures of hydrogen hydrates with structure Ⅰ(SⅠ) and structure H(SH), are studied systematically with molecular dynamics simulation, and the stable structures of hydrogen hydrates are obtained. The structures shows the occupation of hydrogen: there are two H2 molecules in a small cage and three H2 molecules in a big cage in SⅠ hydrate; there are two H2 molecules in a small cage, two H2 molecules in a middle cage, eleven H2 molecules in a big cage in SH hydrate. The radial distribution function(RDF) for hydrogen-hydrogen in each cage of hydrogen hydrate is also investigated. Furthermore, the stable positions of hydrogen in each cage are determined. With these stable positions, the hydrogen storage capability of the hydrate is 5.085%(mass fraction) for SⅠ and 6.467%(mass fraction) for SH. Compared to experiment, it is found that the hydrogen storage capacity of the SH hydrate with the stable structure is most excellent.