| Summary: | Carboxylate surfactants derived from hydrolysis of a renewable triglyceride were adopted as promoters in the synthesis of methane hydrate. The paper investigated the effects of surfactant carbon chain length, different counter ions, salt concentration, and additives on the promotion. It was found that sodium laurate (SL) exhibited better performance than the other surfactants, i.e., sodium decanoate (SD), sodium myristate (SM), sodium palmitate (SP), and sodium oleate (SO). At 4 mmol/L SL, the gas-storage capacity could reach 144 (v/v, the volume of methane stored by one volume of hydrate) during an induction time as short as 17 min. The decomposition of methane hydrate with SL as a promoter could avoid surfactant loss and make its recycling feasible because there was nearly no foam produced. Though sodium chloride, alcohols, and alkane could make the SL solution more surface-active, they have no obvious or even negative effect on methane hydrate formation. The high methane-storage capacity, short reaction time, and no foam generation during hydrate decomposition make SL a promising promoter to be used in large-scale applications.
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