Molecular Dynamics Study of Kinetic Hydrate Inhibitors: The Optimal Inhibitor Size and Effect of Guest Species

Takuma Yagasaki, Masakazu Matsumoto, Hideki Tanaka

    Research output: Contribution to journalArticlepeer-review

    20 Citations (Scopus)

    Abstract

    We propose a model for slowing down of clathrate hydrate formation caused by kinetic hydrate inhibitors (KHIs) on the basis of the Gibbs-Thomson effect. The residence time of inhibitor molecules bound to the hydrate surface and the intrinsic growth rate of the clathrate hydrate without KHIs are key ingredients of the model. The binding free energies of the monomer, dimer, tetramer, and octamer of a KHI, polyvinylcaprolactam (PVCap), are calculated using molecular dynamics simulations to estimate the residence times, which are far beyond the feasible simulation time. Our model accounts for the kinetic inhibition mechanism while reproducing experimental data of the size dependence of PVCap very well. We demonstrate that this model explains why blends of high and low-molecular-weight polymers show better performance than the KHI with a unimodal molecular weight distribution and why quaternary ammonium cations are good KHIs for tetrahydrofuran hydrate although they cannot inhibit formation of natural gas hydrates.

    Original languageEnglish
    Pages (from-to)1806-1816
    Number of pages11
    JournalJournal of Physical Chemistry C
    Volume123
    Issue number3
    DOIs
    Publication statusPublished - Jan 24 2019

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Energy(all)
    • Physical and Theoretical Chemistry
    • Surfaces, Coatings and Films

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