Study of THF Hydrate Crystallization Based on In Situ Observation with Atomic Force Microscopy
Xin Huang, Yajun Deng, Zhenchao Li, Wenjiu Cai, Lijuan Gu, Hailong Lu
Abstract
The crystallization process of a droplet of tetrahydrofuran (THF) solution on a silicon wafer is studied based on the in situ observation with a high-resolution atomic force microscope. On the basis of the results obtained, the crystallization process of the THF clathrate hydrate can be separated into two stages, namely, the ripening stage in the beginning of hydrate formation and the steady growth stage. In the ripening stage, hydrate crystals undergo the Ostwald ripening process, in which the large central hydrate particle grows slowly, and the small hydrate crystals experience dynamic formation-dissociation. In the steady growth stage, hydrate crystals grow at a relatively higher rate, and special features such as dendrites and protrusion along grain boundaries are observed at the surface of hydrate crystal as caused by the supercooling of the experimental system.