Rapid Growth of the CO₂ Hydrate Induced by Mixing Trace Tetrafluoroethane

Rapid formation of the CO₂ 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 CO₂ 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/CO₂ hydrate. The results show that the CO₂ 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/CO₂ 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 CO₂ hydrate, thus promoting the formation of CO₂ hydrate. This paper provides a novel, simple, and efficient method for CO₂ hydrate gas storage technology.