Molecular Insight into the Growth of Hydrogen and Methane Binary Hydrates

Abstract

H2 is considered as the ideal fuel; however, the storage and transportation of H2 limit its usage. Clathrate hydrates are candidate materials for H2 storage and transportation. Because of the extreme conditions necessary to stabilize the pure H2 hydrate, additives are proposed to stabilize a mixed H2 hydrate. Compared to the widely studied H2 + tetrahydrofuran binary hydrates, H2 + CH4 binary hydrates contain a higher energy density. In this study, we study the growth of H2 + CH4 binary hydrates for two sets of temperature and pressure conditions by using molecular dynamics simulations with atomic models. Our results show that CH4 acts as a thermodynamic promoter for H2 + CH4 hydrate formation, while H2 acts as a kinetic promoter for H2 + CH4 hydrate growth at some of our working conditions. We find that there is a maximum growth rate of H2 + CH4 binary hydrates at 250 K when the pressure is 50 MPa, and at fixed temperature, the growth rate of H2 + CH4 binary hydrates shows a positive correlation with pre...