Accelerated methane storage in clathrate hydrates using surfactantstabilized suspension with graphite nanoparticles

In this study, enhanced kinetics of methane hydrate formation in the sodium dodecyl sulfate (SDS) solution with different concentrations of suspended graphite nanoparticles (GNPs) were investigated at 6.1-9.0 MPa and 274.15 K. The GNPs with rough surfaces and excellent thermal conductivity not only provided a considerable number of microsites for hydrate nucleation but also facilitated the fast hydrate heat transfer in the suspension system. At a relatively low pressure of 6.1 MPa, the suspension with 0.4 wt% of GNPs exhibited the minimum induction time of 22 min and maximum methane uptake of 126.1 cm³·cm^-3. However, the methane storage performances of the suspensions with higher and lower concentrations of GNPs were not satisfactory. At the applied pressure, the temperature increase arising from the hydrate heat in the suspension system with the optimized concentration (0.4 wt%) of GNPs was more significant than that in the traditional SDS solution. Furthermore, compared with those of the system without GNPs, enhanced hydration rate and storage capacity were achieved in the suspensions with GNPs, and the storage capacities were increased by 3.9%-17.0%. The promotion effect of GNPs on gas hydrate formation at low pressure is much more obvious than that at high pressure.