Thermodynamic and Kinetic Investigations of Clathrate Hydrates: Applications to Energy Gas Storage and Separation

Abstract

Clathrate hydrates are crystalline inclusion compounds in which a hydrogen-bonded water lattice encapsulates guest molecules, typically light gases or small organic compounds. Understanding their thermodynamic stability and kinetic behavior is crucial for optimizing their applications in energy gas storage and separation. This dissertation investigates the thermodynamic and kinetic properties of various clathrate hydrate systems, focusing on their potential for methane and hydrogen storage, as well as methane enrichment from gas mixtures. By integrating phase equilibrium measurements, crystallographic analysis, and spectroscopic techniques, this work provides a comprehensive understanding of the molecular interactions governing hydrate formation for Energy gas storage and separation. The dissertation is divided into two main parts. Part 1 explores thermodynamic and kinetic strategies for enhancing hydrate-based natural gas storage. Chapter 2 examines the role of cyclopentyl amine (CPA) as a tunable thermodynamic promoter for methane hydrates, characterizing its impact on phase stability and cage occupancy. Chapter 3 extends this approach to multicomponent natural gas storage, where epoxycyclopentane (ECP) is evaluated for its ability to modulate hydrate formation kinetics and increase gas storage capacity. The findings highlight the importance of molecular tuning for optimizing hydrate-based storage systems. Part 2 investigates hydrate-based gas separation, focusing on methane enrichment from hydrogen-natural gas blends. Chapter 4 assesses the stabilization of hydrogen hydrates using gas-phase thermodynamic promoters, elucidating their effects on hydrate phase behavior and guest molecule distribution. Chapter 5 examines selective methane enrichment via hydrate formation, demonstrating how tailored hydrate structures can enhance methane selectivity over hydrogen. These results provide a foundation for developing efficient hydrate-based gas separation technologies. In conclusion, this dissertation presents strategies based on the unique cage occupation behavior of guest molecules, coupled with the thermodynamic and kinetic properties of clathrate hydrates for gas storage and separation applications. The findings emphasize the significance of leveraging intrinsic hydrate properties to enhance gas storage capacity and selectivity, offering insights for the advancement of hydrate-based technologies in energy and environmental applications.