Adsorption behavior of kinetic inhibitors on hydrate surfaces and its relation to the inhibition performance

• KHIs prefer to adsorb on the open cages on the hydrate surface. • Hydrogen bonding anchors KHIs on the hydrate surface. • Hydrophobic attraction enhances the adsorption strength of KHIs. • Adsorption ability of KHIs increases with increasing alkyl side chain length. • Reactivity of KHIs increases with increasing alkyl side chain length. Adsorption behavior of poly(N-vinyl alkanamide)s with varying alkyl side chains on hydrate surfaces and its relation to the kinetic hydrate inhibition performance has been studied by the first-principles method. The results show that inhibitors are strongly adsorbed on the hydrate surface, because of hydrogen bonding and hydrophobic interactions, and then disrupt the water cage structure. As the alkyl side chain increases, the adsorption affinity of inhibitors increases, in accordance with the trend of experimental inhibition efficiencies. Structure and electronic property analysis indicates that the adsorption affinity of inhibitors correlates strongly with their molecular reactivity.