Production process development of natural gas hydrate and physicochemical analysis of artificial hydrate materials as new energy resources

Abstract

Clathrate hydrates, commonly called as gas hydrate, are non-stoichiometric crystalline inclusion com-pounds that are formed by physical interaction between host molecules (H2O) and relatively small gase-ous/liquid/ionic guest molecules. When water molecules are placed in a relatively high pressure condition (filled by gaseous guest molecules) or mixed with certain concentration of specific chemicals at low tempera-ture, the water molecules form linkage through hydrogen bonds and form “cage” framework which can stably accommodate guest molecules. Clathrate hydrates have been applied to many industrial fields of energy and environments, such as exploitation of naturally occurring gas hydrate, energy storage, carbon dioxide sequestration and selective separation of targeted component. In this study, kinetic, thermodynamic and spectroscopic analysis of host-guest interactions on clathrate hydrates were intensively investigated, especially focused on development of production process of natural gas hydrates and application of clathrate hydrate as new energy resources. The scope of this study can be divided into three fields. First, recovery of methane from gas hydrates by replacement technique (also known as ‘swapping technique’) performed in naturally existing sediment and 1-D (9.6m) reactor was studied. The replacement technique swaps methane molecules in the gas hydrate lattice with carbon dioxide molecules. Second, hydrogen storage in clathrate hydrate structure. Beyond the storage of hydrogen molecules in the clathrate hydrate, atomic hydrogen generation and storage in the clathrate hydrate structure was investigated. Third, new spectroscopic instrument was applied to clathrate hydrate system: Terahertz time-domain spectroscopy (THz-TDS). First topic: The direct recovery rate and recovery mechanism of methane from massive methane hy-drates (MHs), artificial MH-bearing clays, and natural MH-bearing sediments are demonstrated, where either CO2 or a CO2 + N2 gas ...