Continuous and efficient production of CH4/THF/DIOX composite hydrates for energy dense storage under moderate conditions

Abstract

Hydrates provide a new approach for energy dense storage under moderate conditions, but poor hydration efficiency and the inability to continuously produce hydrates impede their commercialization. In order to address these two issues, a novel strategy was proposed to achieve hydrate continuous and efficient production under moderate conditions, the dual thermodynamic promoter of THF and DIOX was used to improve hydrate production pressure, D-leucine was employed to accelerate hydrate production kinetics, while the integration of hydrate generation, separation and storage was achieved using a spiral-agitated reactor. Exceptional hydrate production efficiency, conveying efficiency and storage efficiency were obtained, 90 % hydrate production can be completed within 19.21 min, the storage tank can be fully filled within 10 min, and methane apparent storage capacity in the storage tank is up to 79.21 V/V at 3.8 MPa, the energy storage density increases 87.08 % comparing with compressed methane. Raman spectroscopy was used to evaluate hydrate structures, and it is evident that a composite hydrate of CH₄/THF/DIOX was formed. The proposed strategy simplifies hydrate production process, causing it to be more energy-efficient, and the average energy consumption for producing one mole hydrates is only 0.00973 kW·h.