Chemical Engineering Journal, Vol.361, 12-20, 2019
N2O hydrate formation in porous media: A potential method to mitigate N2O emissions
Increasing nitrous oxide (N2O) emissions and their potential impacts on the ozone layer are of worldwide concern. Hydrate-based sequestration technology is considered to be a promising method for N2O control. This study investigated the conditions required for N2O sequestration through forming hydrates. Magnetic resonance imagining (MRI) was used to capture and quantify N2O hydrate formation in porous media simulated by fine quartz sands. The effect of the sequestration conditions on hydrate formation were investigated, involving pressure (1.5, 2, and 2.5 MPa), temperature (275.15, 276.15, and 277.15 K) and initial water saturation (25.06, 33.23, 42.13, and 50.81%). The results indicated the inhomogeneous formation and distribution of N2O hydrates in pore spaces. Initial water saturation and pressure were found to significantly impact the hydrate distribution during the initial formation stage. Moreover, N2O hydrates formed more rapidly in sediments with a lower water saturation and temperature, indicating that sufficient contact between gas and water and a higher driving force are crucial for abundant hydrate formation. A higher initial water saturation could help improve the sequestration efficiency, which would play a crucial role in locating the sequestration site. This work could provide some insights of the mechanism of N2O sequestration via hydrate formation in sediments, making contributions to potential applications in field tests.