Methane hydrate preparation is an effective method to store and transport methane.In promoters to facilitate methane hydrate formation,homogeneous surfactant solutions,sodium dodecyl sulfate (SDS) in particular,are more favorable than heterogeneous particles,thanks to their faster reaction rate,more storage capacity,and higher stability.Foaming,however,could not be avoided during hydrate dissociation with the presence of SDS.This paper investigated the ability of five fluorinated surfactants: potassium perfluorobutane sulfonate (PBS),potassium perfluorohexyl sulfonate (PHS),potassium perfluorooctane sulfonate (POS),ammonium perfluorooctane sulfonate (AOS),and tetraethylammonium perfluorooctyl sulfonate (TOS) to promote methane hydrate formation.It was found that both PBS and PHS achieve a storage capacity of 150 (V/V,the volume of methane that can be stored by one volume of water) within 30 min,more than that of SDS.Cationic ions and the carbon chain length were then discussed on their effects during the formation.It was concluded that PBS,PHS,and POS produced no foam during hydrate dissociation,making them promising promoters in large-scale application.