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.