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

Abstract

The synergistic effect of thermodynamic promoter tetrafluoroethane (R134a) and kinetic promoter sodium dodecyl sulfate (SDS) can significantly improve the phase equilibrium conditions required for CO₂ hydrate formation and promote rapid generation of CO₂ hydrate. Based on this, this study investigates the influence of SDS and R134a synergy on the separation of CO₂/H₂ mixed gas using the hydrate method. The research reveals that without SDS addition, R134a hydrate forms first at the gas–liquid interface before CO₂ hydrate induction, hindering gas–liquid exchange. The addition of SDS can inhibit the formation of the hydrate film, enhance the initiator effect of R134a in the CO₂ hydrate formation process, accelerate the nucleation of CO₂ hydrate, and thus synergistically strengthen the separation of CO₂/H₂ mixed gases. Hydrate formation can be achieved at a concentration of 100 ppm of SDS solution, and the synergistic growth effect of R134a and CO₂ hydrate becomes more significant with increasing SDS concentration. Optimal separation efficiency and maximum H₂ concentration are achieved at 500 ppm of SDS, with 42.29 and 54.88% separation efficiency and H₂ concentration, respectively. Decreasing the initial charge temperature has little impact on separation efficiency but significantly reduces the induction time, reducing it to 3 min at 12 °C. This study improved the separation efficiency of CO₂ and H₂ mixed gas, providing a better reference for hydrogen purification by the hydrate method.