Thermodynamic and Spectroscopic Investigations on Gas Hydrates for CO2 Capture and Water Desalination Processes

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. Water resource management is important in the aspects of security, energy, industry, food, and environmental sustainability. To stably provide freshwater, seawater has been considered as the abundant water resource via water recovery and recycling. In recent decades, gas hydrates have received significant attention due to their potential roles in the gas hydrate-based desalination (HBD) process. Therefore, gas hydrates can potentially be utilized in both CO2 capture and seawater desalination technologies with integrated process. Gas hydrates are one of the inclusion compounds which forming the well-known crystallographic structures, sI, sII, and sH have different thermodynamic stability and gas capacity. In this thesis, firstly, investigation of the 3,3-dimethyl-1-butanol (DMB) + N2 + CO2 hydrates at various gas compositions was conducted to evaluate the potential application to gas hydrate-based post-combustion CO2 capture process focused on the thermodynamic and kinetic properties. It was found that the structural transition from sH to sI hydrates at transition point occurred and the sH region hydrates have better thermodynamic and kinetic performance than sI region hydrates in DMB + N2 + CO2 hydrates systems. The finding of this first study can provide significant insight into gas hydrate-based CO2 capture process involving stepwise enrichment of CO2. Secondly, for potential application to a HBD process, three cyclic compounds, cyclopentane (CP), cyclopentanone (CP-one), and cyclopentanol (CP-ol), were selected focusing on a comparison of thermodynamic and kinetic effects. The findings reported that CP-one could be a promising candidate for the HBD process. Therefore, this thesis can show the energy and environmental application potential to both CO2 capture and seawater desalination via gas hydrates