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Molecular Dynamics Simulation of CO2 Hydrate Growth and Intermolecular Weak Interaction Analysis
Chemistry and Technology of Fuels and Oils ( IF 0.6 ) Pub Date : 2022-06-01 , DOI: 10.1007/s10553-022-01398-0
Xianwu Jing , Lili Chen , Youquan Liu , Ziyi Fu

The growth of carbon dioxide (CO2) hydrate in CO2 aqueous solution (box A), and in CO2 aqueous solution with structure I (sI) CO2 hydrate cell as seed (box B) under the same conditions of 275 K and 10 MPa, were simulated respectively. The total simulation time is 5000 ns. The nucleation process is very slow, so it is difficult to observe CO2 hydrate growth in box A without CO2 hydrate seed, CO2 just accumulates to form bubbles, while H2O still remains liquid, the F4 order parameter remains about –0.1. By contrast, beautiful CO2 hydrate in box B grows rapidly, CO2 is trapped in the cages formed by H2O molecules, F4 rises from 0.12 to 0.7 due to the formation of sI hydrate. The density of CO2 hydrate in box B is as high as 1.25 g/cm3, higher than that of seawater, which is beneficial to its permanent sealing on the seabed. In box B, in accordance with the independent gradient model based on Hirshfeld partition (IGMH) analysis, a H2O molecule forms four hydrogen bonds with surrounding H2O molecules, CO2 only has van der Waals interaction with surrounding water cages. In the actual large-scale CO2 storage process, especially for the rapid storage of CO2 in the form of hydrate, it is strongly recommended to pre-add CO2 hydrate crystals into the solution to achieve the purpose of rapid growth of CO2 hydrate.



中文翻译:

CO2水合物生长的分子动力学模拟和分子间弱相互作用分析

二氧化碳(CO 2)水合物在CO 2水溶液中的生长(框A),以及在275 K和相同条件下以结构I(sI)CO 2水合物细胞为种子(框B)的CO 2水溶液中的生长和10 MPa,分别模拟。总仿真时间为 5000 ns。成核过程非常缓慢,因此在没有 CO 2水合物晶种的情况下,很难观察到箱 A 中 CO 2水合物的生长,CO 2只是积累形成气泡,而 H 2 O 仍然保持液态,F4 序参数保持在 –0.1 左右. 相比之下,盒子B中漂亮的CO 2水合物快速增长,CO 2被困在由 H 2 O 分子形成的笼子中,由于 sI 水合物的形成,F4 从 0.12 上升到 0.7。B箱中CO 2水合物的密度高达1.25 g/cm 3,高于海水,有利于其在海底的永久封闭。在方框B中,根据基于Hirshfeld分区(IGMH)分析的独立梯度模型,H 2 O分子与周围的H 2 O分子形成四个氢键,CO 2仅与周围的水笼发生范德华相互作用。在实际的大规模CO 2封存过程中,特别是对于CO 2的快速封存以水合物的形式,强烈建议在溶液中预先加入CO 2水合物晶体,以达到CO 2水合物快速生长的目的。

更新日期:2022-06-01
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