Hydrate-based continuous hydrogen gas separation from mixing gas containing carbon dioxide with cyclopentanone

Clathrate-hydrate-based H 2 separation is superior to conventional separation methods in terms of energy consumption, but the criteria for selecting promoters that facilitate stable hydrate formation and gas separation are unclear. We conducted continuous and batch separation experiments in a CO 2 + H 2 + cyclopentanone (CP-one) system and powder X-ray diffraction (PXRD) measurements of the hydrate formed in this system. While the mole fraction of H 2 in the gas phase increased from 0.60 to 0.90 in continuous separation, CO 2 in the hydrate phase remained at 0.90. PXRD measurements revealed that CO 2 + H 2 + cyclopentanone hydrate possesses the structure II hydrate, suggesting CO 2 and CP-one encapsulation in small and large cages of hydrate. Compared to previous studies using tetrahydropyran and cyclopentane as guest compounds, CP-one with high water solubility facilitated kinetics of the hydrate, encapsulation of CO 2 in the hydrate and more stable separation. This study would provide a comprehensive understanding of selecting guest compounds for hydrate-based separation. • Cyclopentanone facilitates stable formation of structure II hydrates for efficient CO 2 /H 2 separation. • Kinetics of hydrate improves continuous hydrate-based gas separation performance. • PXRD results confirm CO 2 and cyclopentanone possess the sII structure. • The fraction of H 2 rose from 0.60 to 0.90, while CO 2 in the gas phase decreased from 0.40 to 0.10.