Molecular Insights into the Impacts of Calcite Nanoparticles on Methane Hydrate Formation

Despite the potential broad utility of nanoparticles in hydrate-related fields, there remains a paucity of studies on the impacts of nanoparticles on gas hydrate formation. In this study, massive microsecond molecular dynamics simulations were performed to investigate the roles of calcite nanoparticles on the formation processes of methane hydrate. Our results indicate that calcite nanoparticles prefer to be in the water phase close to the water/gas interface. They inhibit methane hydrate nucleation because a layer of bound water with a thickness of 0.75 nm forms around each nanoparticle which results in an extremely low methane concentration region. Thus, methane hydrate nucleates away from the nanoparticle, and no clear connection between the nucleated hydrate and the nanoparticle is observed. The nanoparticles associate easily, and a water layer with a thickness of 1.15 nm forms between the associated nanoparticles. Moreover, methane hydrate growth is not influenced by calcite nanoparticles until the growth front approaches the bound water around the nanoparticle. These molecular insights of the impacts of calcite nanoparticles on methane hydrate formation are beneficial for the application of nanoparticles in hydrate mining and hydrate-related technologies.