PNNL

Abstract

Hydrophobic solid surfaces have been found to promote the formation of gas hydrates effectively, and thus, help to realize the immense potential applications of hydrates in many sectors such as energy supply, gas storage and transportation, gas separation and CO2 sequestration. Despite the well-known effectiveness, the molecular mechanism behind the promotion effect has not been thoroughly understood. In this work, we used both simulation and experimental means to gain insights into the microscopic level of the influence of hydrophobic solid surfaces on gas hydrate formation. On one hand, our simulation results show the presence of an interfacial gas enrichment (IGE) at hydrophobic surface and a gas depletion layer at hydrophilic surface. One the other hand, the experimental results demonstrate the preferential formation of gas hydrate on a hydrophobic surface. The synergic combination of simulation and experimental results points out that the existence of an IGE at hydrophobic solid surface plays a key role in promoting gas hydrate formation. This work provides a clear molecular understanding of the role of hydrophobicity in governing gas hydrate formation as well as interfacial phenomena in general. This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. The calculations were carried out using computer resources provided by the Office of Basic Energy Sciences.