Surfactant effects on gas hydrate formation

Micellar solutions were found to increase gas hydrate formation rate and alter formation mechanism for ethane and natural gas hydrates. A critical micellar concentration (CMC) of sodium dodecyl sulfate water solution was found to be 242 ppm at hydrate-forming conditions, where CMC was best determined by hydrate induction time. At surfactant concentrations above the CMC, hydrate formation rates in a quiescent system increased by a factor greater than 700. Above the CMC, hydrates initiated subsurface around the micelle-solubilized hydrocarbon gas. Developing hydrate particles migrated and adsorbed on the water-wet cell walls at the water-gas interface, where interstitial water-surfactant solution of the packed hydrate particles continued to react at the high rate. The development overcomes major limitations of future hydrate use in an industrial-scale natural gas storage process. (C) 2000 Elsevier Science Ltd. All rights reserved.