Methane storage in clathrate hydrates containing water-miscible oxirane promoters
Funding information: Ministry of Education, Grant/Award Number: 2017R1D1A1B03033000
Summary
As the share of natural gas in the global demand for energy continues to increase, there is a growing need for sustainable, energy-efficient, and cost-effective natural gas storage and transportation technologies. This study investigates methane hydrates (MHs) containing two oxirane compounds, namely, propylene oxide (PO) and epoxyisobutane (EIB), for their potential use in hydrate-based methane storage (HBMS) applications. The microstructures of the MHs containing both PO and EIB were identified as the sII type by high-resolution powder diffraction (HRPD), 13C NMR, and Raman spectroscopy. Moreover, the addition of PO/EIB significantly improved the thermodynamic stability of simple MH. In particular, as EIB increased the equilibrium temperature by 15 K, the EIB + CH4 hydrate remained stable up to ambient temperature (19°C) even under a mild pressure (30 bar). It was also clearly demonstrated that PO and EIB act as simple hydrate formers (SHFs) with good water miscibility. The EIB + CH4 hydrate also showed a remarkable CH4 capacity of 0.117 mol CH4/mol H2O or 117 m3 CH4 (at STP)/m3 hydrate, nearly identical to the theoretical maximum. It is believed that both PO and EIB could potentially be employed to facilitate sustainable and energy-efficient HBMS technologies owing to the combined excellence of their high promotion capability and energy density, and good water miscibility.
Novelty statements
- Both PO and EIB act as powerful promoters with good water miscibility.
- Both PO and EIB act as simple sII hydrate formers.
- Approximately 120 m3 of methane gas can be stored in 1 m3 of EIB hydrate.
