Wei Shuxian, Liu Siyuan, Cao Shoufu, Zhou Sainan, Chen Yong, Wang Zhaojie, Lu Xiaoqing
School of Science, China University of Petroleum, Qingdao 266580, China.
School of Materials Science and Engineering, China University of Petroleum, Qingdao 266580, China.
Molecules. 2021 Nov 23;26(23):7071. doi: 10.3390/molecules26237071.
Owing to a stable and porous cage structure, natural gas hydrates can store abundant methane and serve as a potentially natural gas resource. However, the microscopic mechanism of how hydrate crystalline grows has not been fully explored, especially for the structure containing different guest molecules. Hence, we adopt density functional theory (DFT) to investigate the fusion process of structure I hydrates with CH/CH guest molecules from mono-cages to triple-cages. We find that the volume of guest molecules affects the stabilities of large (56, L) and small (5, s) cages, which are prone to capture CH and CH, respectively. Mixed double cages (small cage and large cage) with the mixed guest molecules have the highest stability and fusion energy. The triangular triple cages exhibit superior stability because of the three shared faces, and the triangular mixed triple cages (large-small-large) structure with the mixed guest molecules shows the highest stability and fusion energy in the triple-cage fusion process. These results can provide theoretical insights into the growth mechanism of hydrates with other mono/mixed guest molecules for further development and application of these substances.
由于具有稳定且多孔的笼状结构，天然气水合物能够储存大量甲烷，并可作为一种潜在的天然气资源。然而，水合物晶体生长的微观机制尚未得到充分探索，尤其是对于含有不同客体分子的结构。因此，我们采用密度泛函理论（DFT）来研究I型水合物与CH/CH客体分子从单笼到三笼的融合过程。我们发现客体分子的体积会影响大笼（56，L）和小笼（5，s）的稳定性，大笼和小笼分别易于捕获CH和CH。具有混合客体分子的混合双笼（小笼和大笼）具有最高的稳定性和融合能。三角形三笼由于有三个共享面而表现出卓越的稳定性，并且具有混合客体分子的三角形混合三笼（大 - 小 - 大）结构在三笼融合过程中显示出最高的稳定性和融合能。这些结果可为含有其他单/混合客体分子的水合物生长机制提供理论见解，以促进这些物质的进一步开发和应用。
