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Molecular Mechanism of the Inhibition Effects of PVCaps on the Growth of sI Hydrate: Unstable Adsorption Mechanism

Abstract

The inhibition properties of kinetic hydrate inhibitors (KHIs) molecules on the dynamic growth hydrate/water interface were investigated by using molecular dynamic simulations. The shape of hydrate interface will be transformed from laminar to funnel by PVCaps. Results indicate the inhibition effect not just depends on the adsorption capacity which was believed to be the determinant of inhibition, because the PVCaps must have some non-binding-hydrate parts that don’t tend to combine with hydrate. By observing the time evolution of distance between the each component of PVCaps and hydrate, the heterocyclic ring of PVCaps mainly makes contribution to adsorption and can adjust itself to contact with hydrate semi-large-cage preferentially. The distance between amide of PVCaps and hydrate is about 4 Å and exceeds the range of general hydrogen bond (3.5 Å), which proves the non-binding-hydrate sites of PVCaps exists. On the other hand, the amide of PVCaps is an intersection in the solid-liquid interface but have no adsorption affinity on hydrate, so that this adsorption pattern causes that the PVCaps in the hydrate interface is not stable. Due to this unstable adsorption, the repeated hydrate destruction phenomenon was revealed by the identification algorithm of hydrate and the calculation of the local number density of methane. The statistical evolution of water rings further proved the existence of non-binding-hydrate parts in PVCaps and the inhibition mechanism to destroy the hydrate cages by PVCaps. This unstable adsorption mechanism may shed light on the development of novel efficient KHIs.

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Publication details

The article was received on 01 Jan 2018, accepted on 08 Feb 2018 and first published on 09 Feb 2018


Article type: Paper
DOI: 10.1039/C8CP00010G
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
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    Molecular Mechanism of the Inhibition Effects of PVCaps on the Growth of sI Hydrate: Unstable Adsorption Mechanism

    J. Xu, L. Li, J. Liu, X. Wang, Y. Yan and J. Zhang, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP00010G

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