Characterization of the Formation and Storage of Methane Hydrate in the Rhamnolipid-Amino Acid Complex System

As natural gas accounts for an increasing proportion of the global energy supply, solidified natural gas (SNG) is considered a reliable way of NG storage and transportation in the future due to its great advantages. However, to overcome the technical problem of slow hydrate formation kinetics, using a large number of chemical synthetic surfactants will have a bad impact on the environment. To avoid the above issues, rhamnolipid, an environmentally friendly biosurfactant, was used as the main promoter, and tryptophan and leucine, both green promoters, were added to achieve a synergic effect. The results showed that rhamnolipid could greatly improve the problem of slow hydrate formation kinetics, but its promoting effect was closely related to its concentration. At its optimal concentration of 3000 ppm, the optimal gas storage capacity increased by 554.6% compared to the pure water system. Leucine and tryptophan have a synergistic effect with rhamnolipids, and the tryptophan complex system can more effectively promote hydrate formation than the leucine complex system.