Effect of Sodium Dodecyl Benzenesulfonate on the Formation Kinetics of Methane Hydrate

At
present, the wide applications of gas hydrate in various fields,
including gas storage and seawater desalination, are mainly restricted
by two limitations: stochasticity of nucleation and slow formation
kinetics. Use of surfactants is a way to improve the nucleation and
growth rate of hydrate. However, not all surfactants could be considered
as effective hydrate promoters, and not all key factors have been
discovered. In this paper, the influence of sodium dodecyl benzenesulfonate
(SDBS) on the nucleation and growth of methane hydrate was experimentally
studied and evaluated in both parallel autoclaves and visible sapphire
reactors. The nucleation rate J and lag time τ0 of hydrate were derived by the penalized maximum likelihood
estimation method, and the performance of SDBS as a hydrate promoter
was evaluated by these two essential parameters. The p value of the permutation test were calculated for comparison to
evaluate the statistical significance of experimental results. In
addition, the whole process of hydrate formation and decomposition
was recorded with a high-resolution camera installed on a visible
sapphire reactor. The results show that SDBS had an obvious kinetic
promoting effect on the nucleation rate and average growth rate of
methane hydrate, while the total amount of methane consumed was less
affected. In the tested range of 110–320
mg/L, the higher the concentration, the stronger the promoting effect.
Moreover, the results show that varied molar gas–liquid ratios
representing either water- or gas-excess conditions had limited influence
on the observed hydrate growth kinetics in the current system. This
work provides evidence and insight that a specific surface additive,
with experimental validation of its kinetic performance and discovery
of key influencing factors, could have the potential to be used in
hydrate-based engineering applications.