A study of high-density clathrate hydrates in the carbon dioxide-water system

Abstract

Gas clathrate hydrates are inclusion compounds in which a guest gas molecule is trapped within a host cage made up of hydrogen-bonded water molecules 1. Sequestration of CO2 in dense hydrate form has been proposed as one solution for rising levels of CO 2 in Earth's atmosphere2. Recent research has predicted the existence of a high-density clathrate structure capable of realizing this goal3. In this thesis, powder x-ray diffraction of the CO 2-H2O system as a function of increasing pressure (0 to 2.5 GPa) at sub-ambient temperatures (250 to 260 K) was performed in pursuit of discovering novel high-density hydrates of CO2. In addition to previously reported clathrate structures4, CO2 FIS Ih, a non-clathrate structure previously unobserved in the CO 2-H2O system but reported in other systems5, was identified and characterized. Using similar experimental techniques, unrelated work on the structural stability of dickite, a layered silicate mineral, is also presented. *Please refer to dissertation for footnotes.