SDS-promoted methane hydrate growth in presence of a superhydrophobic substrate

As one of the most efficient promoters for methane hydrate formation, SDS (sodium dodecyl sulfate) works mainly by causing the hydrates to grow upwards along the reactor sidewall. In this work, super-hydrophobic surface was constructed and adopted for methane hydrate formation, in the aim of revealing the promotion mechanism of SDS. Morphological observations showed that SDS led to violent fluctuation at the gas/liquid interface, which represented the unstable state of the gas/liquid interface during the initial hydrate growth process and reached stable via morphology transformation, either upward growth or outward diffusion, leading to the surface growth of methane hydrates. In-situ Raman Spectra revealed that the fluctuation structure was the combination of water, hydrate mass with cages minorly occupied by methane molecules, and methane hydrates; and with the continuation of the fluctuation phenomenon, the water percentage decreased, the hydrate mass increased and then transformed to methane hydrates gradually.