Hydrate Formation Kinetics in Dry Water Systems Promoted by 1,4-Dioxane for CO ₂ Capture Applications

Hydrate-based carbon capture (HBCC) is a promising alternative to conventional CO2 separation technologies but is limited by slow hydrate formation kinetics and high operating pressures. Dry water (DW), consisting of water droplets coated with hydrophobic silica, enhances gas–liquid contact and promotes hydrate formation. This study investigates the incorporation of 1,4-dioxane as a promoter in DW systems, focusing on powder formation and hydrate formation kinetics. The addition of dioxane significantly altered the DW morphology, initially producing mousse-like textures, necessitating optimization of synthesis parameters. A free-flowing DW–dioxane powder was successfully obtained at 8 wt % silica, blending speed 6, and 150 s mixing time. Hydrate formation kinetics were evaluated using a CO2/H2 fuel gas mixture (40/60 mol %) at temperatures of 273.9–275.2 K and pressures ranging from 6.64 to 9.0 MPa in the presence of 1.0, 3.0, and 5.56 mol % 1,4-dioxane. Kinetic studies revealed that incorporation of 1 mol % dioxane reduced the induction time from 43.56 min (DW alone) to 8.67 min, demonstrating a 5-fold enhancement in nucleation kinetics. The optimized system achieved a maximum normalized gas uptake of 0.0565 ± 0.0012 mol of gas/mol of water after 4 h, representing the highest performance among the conditions tested. In comparison to stirred-tank reactor (STR) systems, DW exhibited more than 4-fold higher normalized gas uptake across all promoter loadings. These results demonstrate that the DW–dioxane system provides a synergistic combination of enhanced kinetics and improved gas storage performance, offering a promising pathway toward more efficient hydrate-based carbon capture.