Influence of Large Molecular Guest Species on the Formation of CH 4 and CO 2 Hydrates

Abstract

Methane hydrates in nature are considered as a future energy resource for natural gas due to their abundance in nature. The presence of all three structures of clathrate hydrates in the nature have been reported. Structural transition in clathrate hydrates in particular with regards to sH hydrates and the influence of large guest molecules is still not well understood. In the current work, we synthesize mixed hydrate of CO2 & CH4 mixture in presence of sH formers, neo-hexane (NH) and tert-butylmethylether (TBME). High-pressure in-situ differential scanning calorimetry was employed to investigate the phase transformation between soild-liquid-gas. We confirmed that CO2 lean mixture (24% CO2 & 76% CH4) forms structure H (sH) hydrate, while CO2 rich mixture (76% CO2 & 24% CH4) forms structure I (sI) hydrate. This study presents new insights to understand the dynamic preference of methane and carbon dioxide in three different types of cages in sH hydrate.