Inclusion of thiophene as a co-guest in a structure II hydrate with methane gas

Abstract

Thiophene and its derivatives are found in crude oils and their molecular sizes indicate they could be clathrate hydrate formers. In this study, the formation of clathrate hydrates in the presence of thiophene and methane gas is identified through spectroscopic and thermodynamic investigations. Powder X-ray diffraction (PXRD) is used in order to identify the crystal structure of the binary (thiophene + CH4) clathrate hydrate, and PXRD patterns of the binary (thiophene + CH4) clathrate hydrate indicate the formation of structure II hydrate with methane gas. The unique inclusion and distribution of guest molecules such as thiophene and methane are verified through Raman spectroscopy. The thermodynamic stability of the binary (thiophene + CH4) clathrate hydrate is also investigated by using high pressure differential scanning calorimetry. The experimental results are valuable for a better understanding of the crystal structure, host-guest interaction and stability conditions in the binary (thiophene + CH4) clathrate hydrate.