Recovery of Methane from Low-Concentration Coalbed Methane via Hydrate Formation Enhanced by –SO3–-Coated Nanopolymers

Low-concentration coalbed methane (LCCBM) is an abundant unconventional natural gas resource, but the utilization efficiency of methane (CH4) is very low. Sodium dodecyl sulfate (SDS) enhances hydration for CH4 recovery but generates foams during hydrate dissociation, limiting continuous production. To address this issue, the –SO3– group was fixed on the polystyrene nanopolymers (named –SO3–@PSNS) for enhancing hydration to recover CH4 from 21.59 mol % CH4/78.41 mol % N2 in this work. The optimal CH4 recovery effect was obtained when SDS concentration was 4 mmol/L and –SO3–@PSNS concentration was 8 mmol/L. Due to the foams generated by the addition of SDS during the hydrate decomposition, THF in the system decreased from 1 mol % to 0.37 mol % after the reaction but only decreased to 0.96 mol % when –SO3–@PSNS was added. –SO3–@PSNS has important prospects for the application of hydrate-based CH4 recovery from LCCBM.