Rapid methane hydrate formation promoted by Ag&SDS-coated nanospheres for energy storage

Abstract

Gas hydrates have been endowed with great potential in energy storage (e.g. natural gas) and rapid formation of gas hydrates with high storage capacity is critical to use this novel technology. Sodium dodecyl sulfate (SDS) has been confirmed as the most efficient promoter for gas hydrate formation, however, the foam generation during hydrate dissociation caused by SDS cannot be neglected. Although fixing SDS on the surface of polymer nanospheres (SDS@PSNS) can obviously inhibit the foam generation, the hydrate formation rate is also reduced. In this work, for the first time we grafted nano-Ag particles of 2–5 nm on the surface of SDS@PSNS to improve the promotion efficiency and this was confirmed by the experimental results. Without Ag-arrayed, SDS@PSNS of 0.1 mmol/L resulted in the methane hydrate formation lasting for 422.7 ± 63.5 min with the storage capacity reaching 155 ± 6.2 v/v; while after nano-Ag particles were arranged, the hydrate formation periods were shortened to 156.7 ± 24.4–273 ± 31.5 min and the storage capacity reached 146.7 ± 1.2–148.7 ± 3.8 v/v for nano-Ag of 5–50%. When Ag&SDS@PSNS with Ag of 25% was used at 0.2 mmol/L, the hydrate formation was completed within 42.3 ± 3.9 min and the storage capacity reached 144 ± 1.4 v/v, indicating rather efficient promotion to methane hydrate formation. Moreover, Ag&SDS@PSNS produced much better promotion and caused obviously less foam generation compared with SDS at the same concentration. In summary, the Ag&SDS-coated nanospheres developed in this work were of great potential in achieving the industrial application of gas hydrates technology and therefore were significantly meaningful in the field of energy storage.