Effecst of water on the methane hydrate formation and dissociation with hollow silica and activated carbon

Abstract

The porous materials, hollow silica (HSC) and activated carbon (AC), were selected to investigate their effects with water on methane hydrate formation and dissociation. The methane hydrate formation with the porous materials was conducted at 8 MPa and 277 K. The dissociation of hydrates was achieved by thermal stimulation with 294 K temperature driving force. The result showed that the hydrate formation of the system with 1:14 HSC to water ratio, the system with excess water, provided the highest methane consumed and water conversion to hydrates. That is because the HSC has low density allowing it to float on water and small particle size leading to the highest volume of water in the system. However, the excess water increased the mass transfer resistance obstructing the gas to dissolve into the water. The system with 1:0.8 AC to water ratio, water deficit, had the lowest methane consumed and water conversion to hydrates. That is because its hydrophilic nature and capillary effect caused by AC small pores. This resulted in the insufficient water to convert to hydrates and led to the low methane consumed. However, the AC has a large surface area and can adsorb methane. And that may aid the gas solubility and fast induction time of the system with the AC. The final methane recovery was about the same in the systems with the HSC and AC at the same temperature driving force (294 K). Therefore, the amount of water and type of porous materials could play important roles on the methane hydrate formation.