分子动力学模拟研究ZIF-8颗粒对甲烷水合物形成过程的影响

为了揭示ZIF-8颗粒对甲烷水合物形成过程的微观影响机理，通过分子动力学模拟方法研究了有/无ZIF-8颗粒体系中的甲烷水合物成核及生长过程。结果表明：ZIF-8颗粒的加入会影响甲烷水合物的成核及生长动力学，加速或减缓水合物的成核及生长过程。ZIF-8不同的加入量对水合物形成动力学亦有着不同的影响作用。其中，加入少量的ZIF-8颗粒可在不降低水溶液中甲烷过饱和度的情况下，通过加速甲烷分子在水溶液中的运移及水分子的组装行为，促进水合物前驱体及闭合笼状结构的形成，推动水合物的快速成核及生长。当加入的ZIF-8颗粒达到一定浓度时会在短时间内吸引更多的甲烷分子从水溶液中逃离出来并在其表面聚集成纳米气泡，致使水溶液中的甲烷浓度降低、水合物形成驱动力下降，最终导致水合物的形成过程被明显地抑制。

Molecular Dynamics Simulation Study on the Effect of ZIF-8 Particles on the Formation of Methane Hydrate

In order to reveal the microscopic mechanism of ZIF-8 particles on the formation of methane hydrate, the nucleation and growth process of methane hydrate in the presence / absence of ZIF-8 particles were studied by molecular dynamics simulation. The results show that the addition of ZIF-8 particles can affect the nucleation and growth kinetics of methane hydrate, and accelerate or slow down the nucleation and growth process of methane hydrate. Different amounts of ZIF-8 also show different effects on the kinetics of hydrate formation. A small amount of ZIF-8 particles can accelerate the migration of methane molecules in aqueous solution and the assembly behavior of water molecules without reducing the super-saturation of methane in aqueous solution, promote the formation of hydrate precursor and encaged structures of methane hydrates. When the added ZIF-8 particles reach a certain concentration, more methane molecules will be attracted to escape from the aqueous solution in a short time and aggregate into nano-bubbles on the surface of ZIF-8, resulting in the decrease of methane concentration in the aqueous solution and the driving force of hydrate formation, and finally the formation process of hydrate is obviously inhibited.