Insights into the synergistic effect of polylactam kinetic hydrate inhibitor and amino acid via molecular dynamics simulations

Technological innovation is urgently needed to solve the problem of hydrate formation in oil and gas transmission pipelines for the flow assurance guarantee. Typical kinetic hydrate inhibitors for industrial application are the combination of lactam-based polymers with solvent synergists. In this study, a novel non-solvent synergist leucine (Leu) was proposed for improving the kinetic inhibition effect of polyvinyl caprolactam (PVCap). The synergism of PVCap and Leu was investigated via molecular dynamics simulations. Results showed that the 1 wt% PVCap + 2 wt% Leu system can totally inhibit methane hydrate formation within the simulation period, and the combination systems with other concentrations have negligible effects on delaying hydrate nucleation but can significantly slow down the hydrate growth rate. The excellent synergism of PVCap and Leu may be due to the large diffusion coefficient of the molecules in the systems, which provides a high probability for the aggregation of methane molecules and induces the formation of bubbles. In addition, the bubbles can be further stabilized by the amphiphilic PVCap and Leu molecules around it. This study also provides new insights to develop powerful synergists for PVCap, which would be helpful to the design strategy of KHIs with high efficiency.