分子模型SPC/Fw-EPM2对CO_(2)水合物动力学及热力学特性表征

Characterization of Microscopic Properties of CO_(2) Hydrate Using Molecular Model SPC/Fw-EPM2

CO_(2)水合物在碳捕集和封存、空调蓄冷、海水淡化等工程领域均具有潜在的应用价值,但是受到水合物合成诱导期长、过冷度大和生长速率缓慢等问题的制约。分子动力学模拟能够在微观尺度模拟水合物动力学行为,描述微观特性,为解决以上动力学问题提供理论支撑。然而,分子模型不同,水合物的宏观性质也有较大差异,而且不同热力学条件下不同分子模型也表现出不同的特点。为此,以分子模型SPC/Fw-EPM2为例,通过表征CO_(2)水合物的微观结构特性,拟合分解速率与温度的依赖性,计算活化能以及平衡温度等,得到CO_(2)水合物的动力学和热力学性质。通过对比实验结果,提出分子模型SPC/Fw-EPM2能够较好的描述CO_(2)水合物微观特性,为微观机理的探索提供理论支撑。

CO_(2) hydrate has potential applications in carbon capture and storage,air conditioning cold storage,and seawater desalination.However,it is restricted by the problems of long induction period,large subcooling degree and slow growth rate of hydrate formation.Molecular dynamics simulation can be used to simulate the dynamic behavior of hydrates at the microscopic scale,describe the microscopic characteristics,and provide theoretical base for solving the above dynamical problems.The macroscopic properties of hydrates are also quite different due to different molecular models,and different molecular models also show different characteristics under different thermodynamic conditions.In this paper,the molecular model SPC/Fw-EPM2 is taken as an example,the characteristics of CO_(2) hydrate is obtained by characterizing the microstructure,fitting the dependence of decomposition rate and temperature,calculating activation energy and equilibrium temperature,etc.The characteristics are compared with reported experimental results.It is found that the molecular model SPC/Fw-EPM2 can describe the microscopic properties of COhydrate well,providing theoretical support for the exploration of the microscopic mechanism.