储氢笼型水合物生成促进机理的分子动力学模拟研究

用分子动力学(MD)模拟方法研究水合物法储氢的促进机理,系统研究纯H₂水合物、H₂+四氢呋喃(THF)水合物、H₂+四丁基溴化铵(TBAB)半笼型水合物和H₂+四异戊基溴化铵(TiAAB)半笼型水合物的微观结构及性质.模拟分析客体与笼子之间的稳定能ΔE_GH,得出水合物中大笼子对稳定水合物起到主要作用.THF进入大笼子能促进H₂水合物稳定,降低H₂水合物形成压力,模拟结果与实验一致.模拟对比不同客体在大笼子中的ΔE_GH值,得出从小到大的顺序依次为TiAAB,TBAB,THF,H₂.模拟结果表明半笼型水合物的稳定性比结构Ⅱ型水合物强,同时得出H₂+TiAAB半笼型水合物的结构最稳定.MD模拟为TiAAB成为一种水合物新型促进剂和新型储氢材料提供了理论依据.关键词：2笼型水合物')" href="#">H₂笼型水合物分子动力学模拟储氢半笼型水合物

Molecular dynamics simulation of promotion mechanism of store hydrogen of clathrate hydrate

Molecular dynamics(MD) simulation is used to study the promotion mechanism of store hydrogen via the hydrate formation. The stable structures and the microcosmic properties of pure H₂ hydrate, H₂+tetrahydrofuran (THF) hydrate, H₂+tetra-n-butylammonium bromide (TBAB) and H₂+tetraisoamylammonium bromide (TiAAB) semiclathrate hydrates are investigated systematically. The stabilization energy, ΔE_GH, between guest and cavity is calculated. It is shown that the large cavity of hydrate plays a main role of stabilizing hydrate. THF in large cavity can promote the stabilization of hydrogen hydrate and reduce the pressure of formation hydrogen hydrate, which are the same as the experimental results. Compared with the ΔE_GH between guest and large cavity, the results are in the order of increase as TiAAB,TBAB,THF,H₂. It is concluded that the stability of semiclathrate hydrate is better than the structure Ⅱ hydrate, and H₂+TiAAB semiclathrate hydrate is stablest. MD simulation provides helpful information for future TiAAB semiclathrate as a new promoter of forming hydrate and a new hydrogen storage material.