Sodium p-styrenesulfonate serving as an effective and non-foaming promoter for methane hydrate formation

The industrial implementation of hydrate-based natural gas storage and transportation faces significant challenges due to sluggish hydrate formation kinetics. This study systematically explored the use of sodium p-styrenesulfonate (SS) as a promoter for methane hydrate formation, with comprehensive investigations into its promotion efficiency, underlying mechanisms, foamability, and recyclability. Results indicated that SS at an appropriate concentration (5-12   mmol   L -1 ) presented a remarkable performance on promoting methane hydrate formation kinetics, and with increasing concentration, the promotion efficiency was initially enhanced and then slightly declined, and the shortest induction time of 0   min was achieved at 7   mmol   L -1 , while the rapidest hydrate growth rate at t 90 (HGR t90 ) of 0.575 ± 0.022   mmol   mL -1 min -1 , the largest methane uptake of 149.8 ± 0.8   mmol   mol -1 and the highest storage capacity of 148.5 ± 0.8   v/v were achieved at 10   mmol   L -1 . Morphological observation on hydrate formation process revealed that SS might induce the development of porous hydrate structures. These structures generated substantial capillary forces on the underlying water, promoting upward hydrate growth and significantly enhancing mass transfer. Hydrate formation from droplet implied that SS at a higher concentration might provide stronger capillary forces on water, thereby more significantly boosting mass transfer. Morphological observation on hydrate dissociation process revealed that SS did not generate foam, and moreover, SS maintained remarkable promoting effects throughout at least five repeated hydrate formation-dissociation cycles, which convincingly proved that SS permitted exceptional non-foamability and admirable recyclability.