Kinetic inhibitor of hydrate crystallization.

We present the results of a combined theoretical/experimental study into a new class of kinetic inhibitor of gas hydrate formation. The inhibitors are based on quaternary ammonium zwitterions, and were identified from a computational screen. Molecular dynamics simulations were used to characterize the effect of the inhibitor on the interface between a type II hydrate and natural gas. These simulations show that the inhibitor is bifunctional, with the hydrophobic end being compatible with the water structure present at the hydrate interface, while the negatively charged functional group promotes a long ranged water structure that is inconsistent with the hydrate phase; the sulfonate-induced structure was found to propagate strongly over several solvation shells. The compound was subsequently synthesized and used in an experimental study of both THF and ethane hydrate formation, and was shown to have an activity that was comparable with an existing commercial kinetic inhibitor: PVP.