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甲烷可以与水形成由大、小孔穴构成的I型水合物,该过程受温度的影响。采用分子动力学(MD)模拟方法,在等温等容(NVT)模拟条件下,研究了温度变化对水合物晶体及其中大、小孔穴结构及稳定性的影响。通过分子模拟分析晶体构型、氧原子均方位移、甲烷分子位移和相互作用能,结果表明:水合物晶体的稳定性受温度的影响较大,且其主要由大孔穴的稳定性决定;温度对大孔穴的结构及稳定性的影响较大,随着温度的升高,大孔穴稳定性明显降低,笼形结构变形增大,甚至出现坍塌,导致水合物分解;温度对小孔穴结构及稳定性的影响较小,相同条件下水合物中小孔穴的稳定性高于大孔穴的稳定性。研究成果可为水合物形成过程的控制、水合物快速分解、水合物稳定储存等提供理论基础。
Methane can form a type I hydrate consisting of large and small pores with water, which is affected by temperature. The influence of temperature on the crystal structure of hydrate, its structure of large and small holes and the stability of the hydrate crystal were studied by the method of molecular dynamics (MD) simulation under isothermal equivalent volume (NVT) simulation. The crystal structure, the mean square displacement of oxygen atoms, the molecular displacement of methane and the interaction energies were analyzed by molecular simulation. The results show that the stability of hydrate crystals is greatly affected by temperature and is mainly determined by the stability of macropores. The temperature Which has a great influence on the structure and stability of macropores. With the increase of temperature, the stability of macropores decreases obviously, the deformation of cage structure increases and even collapses, resulting in the decomposition of hydrates. The effect of temperature on the pore structure and stability The effect of sex is small. The stability of small holes in hydrates under the same conditions is higher than the stability of large holes. The research results can provide the theoretical basis for the hydrate formation process control, rapid hydrate decomposition, and stable hydrate storage.