Observation of distinct structural transformation between sI and sH gas hydrates and their kinetic properties during CO2 capture from N2 + CO2

Abstract

sH hydrate has a deal of attention as an attractive medium of gas storage and separation due to its relatively milder formation condition and higher storage capacity, and thus sH hydrate has focused on the potential application in the post-combustion CO2 capture. Nonetheless, in-depth investigations on the thermodynamic stability of sH hydrate of N2 + CO2 and the possible occurrence of structural transformation during the process have not yet been addressed. Since the gas hydrate-based CO2 capture technology involves stepwise enrichments of CO2 through iterative formation-dissociation processes of CO2 hydrate, knowledge about the thermodynamic stability between sI and sH hydrates in the presence of various N2:CO2 ratios and their kinetic properties is important for designing the gas hydrate-based CO2 separation process. Here, we explored sI and sH hydrates of 3,3-dimethyl-1-butanol + N2 + CO2 focusing on their structural stability and structure-dependent kinetic properties. The experimental data including P–T phase equilibria, induction time, gas uptake, and CO2 separation factor are provided with a structural analysis via synchrotron high-resolution powder diffraction.