Zwitterionic polymeric hydrogels promote CO₂ hydrate formation kinetics: An experimental study

Hydrogels are appealing support structures for the promotion of clathrate hydrate by increasing the gas–liquid contact surface area. However, due to their soft and adhesive nature, the current hydrogel materials cannot independently support the formation of hydrates. In this work, we used free radical polymerisation to develop a set of hydrogels with varied functionality and density, and investigated the effect of hydrogel composition on its reusability and ability to promote CO₂ hydrate formation kinetics. The hydrogels demonstrate better recyclability than those reported in literature and the sample with the composition methacrylic acid: [2-(methacryloyloxy) ethyl] trimethylammonium chloride:ethylene glycol dimethacrylate = 47.5:47.5:5 exhibits optimal performance, with a normalised CO₂ hydrate growth rate during the initial 30 min (NR₃₀) of 187.23 mol m⁻³ min⁻¹, and an 8-hour water-to-hydrate conversion rate (CR_8h) of 86.3 %. This study demonstrates the ability for molecular engineering of the hydrogel structure to enhance gas hydrate formation kinetics for the practical realization of hydrate-based carbon capture technology.