Investigation of Thermodynamic and Kinetic Properties of Structure H Gas Hydrate for Potential Application to CO2 Capture

Abstract

With the accelerating of global warming, a variety of CO2 capture technologies have been investigated so far. Among the options, the gas hydrate-based CO2 separation is recognized as an emerging technology due to the advantage of small energy penalty and the low energy consumption of CO2 capture. Gas hydrate is one of the inclusion compounds which forming the well-known crystallographic structures, sI, sII, and sH have different thermodynamic stability and gas capacity. sH hydrate has a deal of attention as attractive media of storage and separation due to their mild formation conditions and high storage capacity. In this study, firstly, I investigated the 3,3-dimethyl-1-butanol (DMB) + N2 + CO2 hydrate at various gas compositions to evaluate the potential application to gas hydrate-based post-combustion CO2 capture process focused on the thermodynamic and kinetic properties. Secondly, I verified the sH tuning phenomenon to maximize the gas capacity of sH hydrate by using 1-methylpiperidine (1-MPD) + CH4 hydrate with 13C NMR spectroscopy analyses. Based on the phase equilibria measurements, HRPD analyses, and kinetic experiments, it was found that the structural transition from sH to sI hydrate at transition point occurred and the sH region hydrates have better thermodynamic and kinetic performance than sI region hydrates in DMB + N2 + CO2 hydrate systems. Fortunately, it was observed that occurring of the sH tuning effect in 1-MPD + CH4 hydrate with a critical concentration of 2.4 mol% for the first time.