Rapid Growth of the CO₂ Hydrate Induced by Mixing Trace Tetrafluoroethane

Abstract

Rapid formation of the CO 2 hydrate can be significantly induced by the gaseous thermodynamic promoter 1,1,1,2-tetrafluoroethane(R134a) due to the mild phase equilibrium conditions, although the formation mechanism and dynamic behavior are not clear. Therefore, a visual experimental system was developed to study the effects of different concentrations of R134a on the induction time, gas consumption, and growth morphology of the CO 2 hydrate. At the same time, the combined effects under stirring and sodium dodecyl sulfate (SDS) systems were also studied. In addition, visualization and experimental model diagrams were combined to explain the fast formation mechanism of the R134a/CO 2 hydrate. The results show that the CO 2 hydrate average conversion rate was increased by more than 63% with the addition of mixed trace R134a(7%). A special phenomenon is found that two temperature peaks appear on the hydrate formation temperature curve, corresponding to two different stages of hydrate formation when stirring or SDS is added to the mixed gas reaction system. Furthermore, the gas consumption in stirring and SDS systems increases by 9 and 44%, respectively. Finally, it is also found that the R134a/CO 2 mixed hydrate formed under the action of SDS has a "capillary" mechanism, which provides a gas− liquid phase exchange channel and a large number of nucleation sites for CO 2 hydrate, thus promoting the formation of CO 2 hydrate. This paper provides a novel, simple, and efficient method for CO 2 hydrate gas storage technology.

CO2/H2 Separation by Synergistic Enhanced Hydrate Method with SDS and R134a

“…The formation of mixed R134a + CO 2 hydrates is initiated first, subsequently promoting the generation of CO 2 hydrates. It is comparable to the process in which R134a promotes the formation of pure CO 2 hydrate in our prior work . As a result, only a small amount of hydrates generated along the reactor wall and the gas–liquid interface by the end of the 300 min experiment.…”

“…It is comparable to the process in which R134a promotes the formation of pure CO 2 hydrate in our prior work. 20 As a result, only a small amount of hydrates generated along the reactor wall and the gas–liquid interface by the end of the 300 min experiment.…”

“…Studies indicate that R134a actively participates in the formation of both pure R134a hydrates and R134a/CO 2 mixed hydrates, both adopting a type II structure . Additionally, investigations by Song et al reveal that the inclusion of R134a significantly reduces the induction time for pure CO 2 hydrate formation. The kinetic promoter dodecyl sodium sulfate (SDS) enhances the gas exchange rate at the gas–liquid interface, thereby augmenting the rate of CO 2 hydrate formation and gas consumption .…”