Hydrate Formation from Gaseous CO_2 and Water

Abstract

Economics of creating CO_2 hydrate on a large scale favor use of gaseous rather than liquid CO_2 as input to the production process. We accordingly studied systems using deionized water and CO_2 gas to reduce formation pressures and costs of hydrate production to the greatest extent possible. Three research avenues were explored:  utilization of hysteresis effects, use of dissolved Snomax (a protein from the bacterium Pseudomonas syringae), and development of a continuous flow reactor (cfr) utilizing vigorous mixing of water and CO_2 gas. Hysteresis effects produced pressure reductions of 14−50%. We demonstrated a method of transferring benefits from the hysteresis effect to a CO_2 water mixture that had not yet undergone hydrate formation. Snomax at 10 ppm by weight produced about a 5% reduction in hydrate formation pressure. We designed and operated a prototype cfr with partial success at producing CO_2 hydrate. The hydrate phase diagram is based on hydrate decomposition pressures and should not be used as an indicator of formation pressures.