Sequestering CO2 via Reaction With Trona Solution

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Sequestering CO2 via Reaction With Trona Solution

• By Nicole Predki
• Research Mentor Klaus Lackner
• Seminar Advisor Chris Scholz
• Experimental Advisor Juerg Matter

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Trona Sodium Sesquicarbonate

• Naturally occurring chemical Na2CO3.NaHCO3.2H20
• Green River Formation in southwest Wyoming
  largest bedded trona resource
• Trona currently mined for soda ash (Na2CO3)
  production

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Green River Formation Southwest Wyoming
Green River Basin
Bedded Trona 17 billion tons
Picture from U.S. Department of the Interior,
U.S.G.S., John R. Dyni, Open File Report 96-729
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Basic Model for CO2 Absorption in Dissolving Trona
Flue Gas pCO2 0.15 atm Atmosphere pCO2
3.710-4 atm
CO2
Water
Dissolution Interface
Trona
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Important Conditions for CO2 Efficient Absorption

• Attainability of Trona- Cost Abundance
• Green River Deposit/Current Mining
• Physical Absorption Liquid Film Thickness
• ? CO3-- _at_ liquid surface gt ? OH- gt ? CO2
  absorption (Vas Bhat, 2000)
• Negative effect on absorption minimized by
• Agitation
• Increasing surface of contact
• Mechanism of Chemical Reactions involved
• Limiting step CO2 H2O ltgt H2CO3
• Correct HCO3-/CO3--
• Catalysts- Carbonic Anhydrase (Tsao, 1971)

?
Liquid Film
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Carbonate-bicarbonate Ratio
Must have less than Equilibrium value of HCO3- to
absorb CO2
http//www.cas.astate.edu/geochemistry/geochemistr
y/downloads/alk1.doc
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Na2CO3-NaHCO3 Solutions CO2

• Equilibrium established between CO2 in air and
  Na2CO3-NaHCO3 liquid
• Na2CO3 CO2 H20 2NaHCO3

Data extracted from Harte, et al, 1933
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Evidence of Na2CO3-NaHCO3 Solutions Absorbing CO2

• Absorption of CO2 in Na2CO3.NaHCO3 solutions
  (Harte et al., 1933)
• Absorption of CO2 in aqueous alkalies (Welge,
  1940)
• Na2CO3 used to absorb CO2 in kimchi packages
  (Shin et al., 2002)
• Solution mining
• Absorption and fixation of CO2 by rock weathering
  (Kojima et al., 1997)

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Ultimate Goal

• Find the most effective method for reacting Trona
  solution with CO2 to form NaHCO3 in solution
• Is Air Extraction Possible?

CO2
NaHCO3
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Factors Involved

• Ratio of carbonate to bicarbonate ions
• Chemical reaction rate
• Properties of air/water interface
• Concentration of carbonate ions near interface
• Catalysts
• Impurities in trona

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Absorption Experiment
Trona solution in beaker exposed to air with
pCO2 Agitation with stir bar pH and T ºC
measured

• Predicted pH in Equilibrium with air is 9.55
• No consistent pH change
• Absorption too slow and small- ? 0.005M CO2
• Other concentrations showed similar results

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Experimental Options

• Perform flow-through dissolution experiment
• Can we recycle Trona?
• Solubility/Precipitation dependent
• Use catalysts to speed hydration of CO2
• Bubble CO2 gas stream though catalyzed solution
• Use a Sprinkler method
• Maximize surface area
• Can different methods be combined?

Flow-through design by Juerg Matter
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Implications

• Environmentally safe, economically favorable
  means to selectively capture CO2
• CO2 at sites of pCO2 equals overall
  atmospheric pCO2 values

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Thank You
Special Thanks to Klaus Lackner, Juerg Matter,
and Chris Scholz
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References

• Dyni, John R.(1995) Sodium Carbonate Resources of
  the Green River Formation. U.S. Geological
  Survey, Open-File Report 96-729.
• Harte, C.R., Baker, E.M., and Purcell, H. H.
  (1933) Absorption of Carbon Dioxide in Sodium
  Carbonate-bicarbonate Solutions. Industrial and
  Engineering Chemistry, 25, 528-531.
• Hitchcock, Lauren B.(1934) Rate of Absorption of
  Carbon Dioxide. Industrial and Engineering
  chemistry, 1158-1166.
• Koch, Howard A., Stutzman, Leroy F., Blum, Harold
  A, and Hutchings, Leroi E. (1949) Gas Absorption
  Liquid Transfer Coefficients for the Carbon
  Dioxide-Air-Water System. Chemical Engineering
  Progress, 45, 677-682.
• Kojima, T., Nagamine, A, Ueno, N., and Uemiya, S.
  (1997) Absorption and fixation of carbon dioxide
  by rock weathering. Energy Conversion
  Management, 38, S461-S466.
• Mehta, Gurmukh D., and Jain, Satish C. (1982)
  Diffusion Coefficient of Trona in Water.
  Industrial Engineering Chemistry Process Design
  and Development, 21, 394-395.
• Nasum-Saygili, Gulhayat, and Okutan, Hasancan
  (1996) Application of the solution mining process
  to the Turkish trona deposit. Hydrometallurgy,
  42, 103-113.
• Rau, Greg H., and Caldeira, Ken (1999) Enhanced
  carbonate dissolution a means of sequestering
• waste CO2 as ocean bicarbonate. Energy
  Conversion Management, 40, 1803-1813.
• Shin, Dong Hyuk, Cheigh, Hong Sik, and Lee, Dong
  Sun (2002) The use of Na2CO3-based CO2 absorbent
  systems to alleviate pressure buildup and volume
  expansion of kimachi packages. Journal of Food
  Engineering, 53, 29-235.