Exploring the Physical Chemistry of the Catalysis-Based All-Vapor Instant Formation of Gas Hydrates at Moderate P and T (180-220 K)

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Prof. Paul Devlin of Oklahoma State University is supported by the Chemical Structure, Dynamics and Mechanisms Program of the Chemistry Division to study the basic physical and chemical properties of clathrate hydrates. Clathrate hydrate formation, typically from liquid water or ice, is so slow as to often discourage studies of the rates and mechanisms of the process. The most exciting and promising discovery from research supported under prior awards is a completely new method of hydrate formation that reduces the reaction time to the subsecond scale. A generally slow mixing process has been shunted by using an all-vapor methodology with component guest molecules fully mixed with water vapor. Pulsed into a cold chamber the vapor quickly condenses to aqueous solution droplets that instantly crystallize as 100% gas-hydrate particles of an aerosol. A catalyst is still required at the current stage of knowledge, but advances in the all-vapor method sought in this phase of the project may aid technological developments in a) the production of methane from abundant ocean-sediment deposits of methane hydrate, and b) the concentration/storage of gases such as methane and CO2 as hydrate guests at greatly reduced pressures. It has been shown, for example, that humid air including CO2 is a vapor mixture suited to the all-vapor formation of a gas hydrate provided a catalyst is includedA clathrate/gas hydrate is most simply described as a host ice-like lattice of water molecules with incorporated small cages that serve as molecule-sized traps holding small organic or inorganic guest molecules. Because of an exceptional abundance in nature and their significant environmental and technological implications, they have been an object of many investigations over the past century. Much is known about their occurrence and physical properties; less about their participation in H-bond chemistry and the mechanisms of their formation. In this project, Prof. Devlin and his undergraduate research assistants will pursue the development of methods of gas-hydrate formation and control that will facilitate gas -hydrate science applications for controlling gases such as carbon dioxide and methane in the energy industry and the environment.