Hydrate Formation from Gaseous CO₂ 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.

Viability of Clathrate Hydrates as CO2 Capturing Agents: A Theoretical Study

“…Two major bottlenecks for industrial applications of these materials are (a) the lower weight percentage and (b) regeneration of the captured gas. The hydrate formation from water and gaseous CO 2 was reported by North et al, where these authors observed the growing hydrate crystals optically and by means of calorimetric methods . X-ray diffraction studies showed the time-resolved macroscopic hydrate formation in the stirred water–CO 2 bulk mixture .…”

“…The hydrate formation from water and gaseous CO 2 was reported by North et al, where these authors observed the growing hydrate crystals optically and by means of calorimetric methods. 13 X-ray diffraction studies showed the time-resolved macroscopic hydrate formation in the stirred waterÀCO 2 bulk mixture. 14 A combined experimental and molecular dynamics study has provided the first unambiguous evidence for the formation of CO 2 gas hydrates at molecular length scales.…”

CO2 Hydrates in Refrigeration Processes

“…The differences in formation conditions between the present data and others might be due to the fact that liquefied CO 2 was not used in this study as is often the case in the literature. 29,30 The studies that examined hydrate for- mation from gaseous CO 2 show higher pressure ranges at ambient temperature 31,32 and at low temperatures based on the injection of gaseous CO 2 on ice crystals. 33 The present method is different from those employed in these studies, because the crystallization of the icehydrate mixture is initiated by a short stirring period of a supercooled CO 2 -saturated solution at low temperatures.…”

INVESTIGATION OF THERMO-PHYSICAL AND FLOW PROPERTIES OF CO2 HYDRATE SLURRY

“…Therefore, it is likely to have the cases where CO 2 hydrates are not easy to form 36,37 ; hydrates lighter than water are formed and°oat as observed by Unruh and Katz 38 and North et al 39 North et al 39 pointed out, based on their experimental observations, that only the freshly formed CO 2 hydrate in water is lighter than water and the matured CO 2 hydrate is heavier than water. With even lower value of molar fraction of CO 2 in the CO 2 hydrate, unstable paste-like CO 2 hydrate composite will be formed.…”