Microsecond Molecular Dynamics Simulations of the Kinetic Pathways of Gas Hydrate Formation from Solid Surfaces

In this paper, we report microsecond molecular dynamics simulations of the kinetic pathway of CO2 hydrate formation triggered by hydroxylated silica surfaces. Our simulation results show that the nucleation of the CO2 hydrate is a three-stage process. First, an icelike layer is formed closest to the substrates on the nanosecond scale. Then, on the submicrosecond timescale, a thin layer with intermediate structure is induced to compensate for the structure mismatch between the icelike layer and the final stable CO2 hydrate. Finally, on the microsecond timescale, the nucleation of the first CO2 hydrate motif layer is generated from the intermediate structure that acts as nucleation seeds. We also address the effects of the distance between two surfaces.