Sodium p-Styrenesulfonate as a Remarkable Kinetic Promoter for CO2 Hydrate Formation: Promotion Efficiency and Mechanism

Slow CO2 hydrate formation kinetics restricts the development and industrial application of hydrate-based carbon capture and sequestration (CCS) technology. Here, sodium p-styrenesulfonate (SSS) was employed as a novel promoter for CO2 hydrate formation, and its efficiency, promotion mechanism, and recyclability were systematically studied. Results indicated that SSS improved the hydrate formation kinetics remarkably and yielded the highest CO2 uptake of 8.033 ± 0.348 mmol mL–1 as well as the rapidest hydrate growth rate (HGR) of 0.437 ± 0.075 mmol mL–1 min–1 at concentrations of 50 and 100 mmol L–1. SSS under a moderate concentration also presented high efficacy; 6 mmol L–1 SSS led to a short induction time of 36.37 ± 32.14 min, a rapid HGR of 0.307 ± 0.029 mmol mL–1 min–1, and a high CO2 uptake of 7.036 ± 0.472 mmol mL–1. Morphological observation revealed that the promotion effects were mainly attributed to the climbing hydrate growth caused by capillary effect, which was markedly influenced by the sidewall hydrophilicity and the SSS concentration. Stronger hydrophilicity of the sidewall and a higher SSS concentration both favored the liquid movement, boosted the climbing hydrate growth, and improved the formation kinetics. Additionally, SSS did not produce foam when hydrates dissociated and kept admirable promotion performance in at least six repeated cycles, indicating its excellent recyclability.