Experimental and theoretical investigation on hydrate nucleation in TBAB droplets

The efficient and rapid formation of natural gas hydrate is of great significance for its large-scale industrial application, which is inseparable from the intensive study of hydrate formation mechanism. Most of the previous studies focused on the growth of hydrate crystals and the effects of different factors on the morphology. However, the research specifically on the nucleation and theoretical analysis of tetra-n-butylammonium bromide (TBAB) hydrate has not been reported. In this work, the nucleation of TBAB hydrate in 2 mu L droplets was studied using high-speed photography. Combined with the classical nucleation theory, a model for calculating the Gibbs free energy required for TBAB hydrate nucleation by fugacity is proposed. Through this model and combined with macro experimental phenomena, it is calculated for the first time that the maximum critical nucleation size of A type TBAB hydrate is about 29(+/- 6) angstrom and that of B-type TBAB hydrate is about 15.6(+/- 6) angstrom. This work has great significance for further study of hydrate formation kinetics.

Automated summary

This study investigated the nucleation process of TBAB hydrate using high-speed photography and proposed a model for calculating the Gibbs free energy required for hydrate nucleation. The maximum critical nucleation size of A-type TBAB hydrate was calculated to be about 29 Å, and that of B-type TBAB hydrate was approximately 15.6 Å, providing insights for further research on hydrate formation kinetics.