Kinetic study of hydrate formation for argon + TBAB + SDS aqueous solution system

Abstract

In this communication, the effects of initial temperature and pressure, aqueous TBAB (tetra-n-butylammonium bromide) solution concentration, and sodium dodecyl benzene sulfonate (SDS) concentration on the kinetic behaviour of semi-clathrate hydrates of Ar+aqueous TBAB solutions were investigated. Kinetic experiments were performed in a high pressure equilibrium cell with an inner volume of approximately 40cm3 at initial temperatures of (281, 285 and 287.5)K and initial pressures of (6.1, 8.1 and 10.1)MPa. The results indicate that induction time decreases significantly with an increase in the initial pressure. However, the kinetic constant, and consumption of Ar during the semi-clathrate hydrate formation, increases. The same trends were detected with a decrease in the initial temperature, at a constant pressure. In addition, with an increase in the TBAB concentration, from 0.1 to 0.3mass fraction TBAB, the rate of semi-clathrate hydrate nucleation and consumption of Ar, increases during the hydrate formation, while the induction time decreases, significantly. The results therefore show a positive kinetic effect of TBAB on Ar hydrates which indicates that TBAB is a reliable promoter to increase the rate of argon hydrate formation. The results for the addition of SDS (at concentrations of 100, 200ppm) at initial temperatures of 285K and initial pressures of (6.1 and 8.1)MPa indicate that SDS increases the induction time of the semi-clathrate hydrate formation for the system of Ar+0.1mass fraction TBAB+0.9mass fraction water, but there is no systematic trend between induction times and the SDS concentrations for this system.