Enhanced Kinetic Inhibition of Gas Hydrate Formation Using the Mixture of Poly(N-vinylcaprolactam) and Ionic Liquids

To investigate the synergetic effect by the mixture of ionic liquids (ILs), consisting of various cations and tetrafluoroborate anion, and well-know polymeric inhibitor, poly(N-vinylcaprolactam, PVCap) tests of kinetic inhibition on natural gas hydrate formation were performed. Results shows that the PVCap-IL mixtures revealed significantly enhanced kinetic hydrate inhibition performance. In particular, the mixture of PVCap and 1-hexyl-1-methylpyrrolidinium tetrafluroborate (HMP-BF4) showed the best hydrate inhibition performance even at higher pressure condition. It exhibited the highest hydrate nucleation inhibiting performance when it was at individual used, additional study was conducted using the mixtures of the two at various concentration combinations. The combination of 1:0.5 via weight basis between PVCap and HMP-BF4 showed the longest induction time. It is presumed that the enhanced synergetic effect of the ILs on the natural gas hydrate inhibition may arise from the prevention of the small cage formation by the ILs, which induces the inhibition of metastable structure I hydrate formation.