Rapid formation of methane hydrates with compact agglomeration via regulating the hydrophilic groups of nanopromoters

Abstract

Abstract Gas hydrates have been endowed with great potential as the medium for natural gas storage & transportation. In this work, we prepared novel nanopromoters by grafting hydrophilic groups (SO 3 − , COO − and N[CH 3 ] 3 + ) covalently on polystyrene nanospheres (Group@PSNS), and for the first time achieved rapid formation of methane hydrates together compact agglomeration by regulating the hydrophilic groups on the surface of nanopromoters. When SO 3 − @PSNS was used, methane hydrates formed rapidly but loosely in the reactor; while for COO − @PSNS and N(CH 3 ) 3 + @PSNS, even the hydrate formation rate was seriously reduced, the formed hydrates agglomerated compactly in the reactor bottom. Interestingly, when both SO 3 − and COO − were fixed on the nanospheres, both the hydrate growth rate and agglomeration compactness were controlled. Especially, the nanopromoter with the SO 3 − /COO − molar ratio of 2:1 resulted in the formation of methane hydrates with compact agglomeration morphology within 1–2 hr and with the storage capacity reaching 140–145 vol/vol.