1. Carbon Dioxide and the Consumer
Micell Technologies

2. Carbon Dioxide (CO2) Natural, cheap, plentiful (too much of it!)
0.04% of atmosphere and apparently rising!
Available in >99.9% pure form, £70/$110 per 25kg.
By-product of brewing, ammonia synthesis, combustion
Non-toxic and properties well understood
asphyxiant at high concentrations (excludes oxygen from lungs)
Non-flammable
Easily removed and recycled, and can be disposed of with no net increase in global CO2

3. The Consumer Perspective
All will have heard of carbon dioxide
Has been widely used in consumer applications for many years (carbonated beverages)
Supply chain and related technology already established.
Relatively good image for consumer
‘Natural’
Probably not thought of as a ‘chemical’
Non-toxic (asphyxiant at high concentrations)
Renewable, non-petrochemical sources available
Definite benefits over potential alternatives

4. • • Phase diagram for pure CO2 Pressure (bar) Temperature (ºC) 74
© Monterey Bay Aquarium Research Institute
SOLID
SUPERCRITICAL
Critical
FLUID •
point
Pressure (bar) 74
LIQUID
Triple •
point
5.1
GAS 1
-78 ºC
-56.3ºC
31.1ºC
Temperature (ºC)

5. • • Pressure (bar) Temperature (K) 74 303 SUPERCRITICAL FLUID SOLID
point •
Pressure (bar) 74
LIQUID
GAS
Triple
point •
Temperature (K)
303

6. • • Pressure (bar) Temperature (K) 74 303 SUPERCRITICAL FLUID SOLID
point •
Pressure (bar) 74
LIQUID
GAS
Triple
point •
Temperature (K)
303

7. • • Pressure (bar) Temperature (K) 74 303 SUPERCRITICAL FLUID SOLID
point
Pressure (bar) 74
LIQUID
Triple •
GAS
point
Temperature (K)
303

8. • • Pressure (bar) Temperature (K) 74 303 SUPERCRITICAL FLUID SOLID
point •
Pressure (bar) 74
LIQUID
GAS
Triple
point •
Temperature (K)
303

9. SCFs are intermediate between liquids and gases

10. What has carbon dioxide ever done for us?

11. Current consumer related applications of CO2 technology
Carbonated drinks
Leavening agents in baking
Solvent extraction
Surface coating
Fumigation (1% in air will eliminate pests in greenhouses)
Dry cleaning
Surface cleaning
Welding
pH control (e.g. effluent streams, pulp and paper mills)
Refrigeration (dry ice, mechanical systems)
Fire extinguishers
Life jackets
Main raw material for photosynthesis (with water)!

12. The Future?

13. Dry Cleaning using CO2 Current methods use perchloroethylene
1.5 Million tons used per year (North America)
Hazardous air pollutant and suspected carcinogen
Contaminates drinking water supplies
Contributes to photochemical smog
<5% recycled
Requires heating to remove solvent residues
Characteristic odour
Use of PERC in EU to be phased out by 2007
Poly(ether-carbonate) coplymers derived from propylene oxide and CO2.

14. Dry Cleaning using CO2 New process uses liquid CO2
Requires surfactant (recycled)
No unpleasant odours
No heat required for drying – energy efficient and kinder on clothes
Possible tax credits and reduced regulatory monitoring
Utilises same CO2 used by food and drink distributors
J.L. Kendall, D.A. Canelas, J.L. Young and J.M. DeSimone,
Chem. Rev., 1999, 99, 2663.
T. Sarbu, T. Styranec and E.J. Beckman,
Nature, 2000, 405, 165.

15. Dry Cleaning using CO2 Hangers (Micell, NC),
DryWash (Global Technologies, CA)
Related technology also used for degreasing (e.g. metal parts), semiconductor photoresist removal and spin coating.
Franchises now operating in Sweden
ICI and Linde now major players
Chem. Eng. News, Sept p12.
Micell Technologies

16. Spray coating using CO2 Union Carbide, Unicarb Technology
Replaces 40-90% of VOCs with CO2.
Widespread application
Coatings on aerospace parts
Adhesion promoters on plastics
Food
Chocolate biscuits
Barrier coatings
Additives
Chem. Eng. News, June , 77 (24), 13.

17. Extraction using scCO2
Extensively used for ‘natural’ coffee decaffeination; alternative uses CH2Cl2 (also tea)
Extraction of Hops for Brewing
Many other extraction processes
Often use liquid rather than supercritical CO2.
Spices
Essential oils and fragrances
Simple product isolation by evaporation, to 100% dryness.
No solvent residues or effluent

18. CO2 Refrigeration
Many refrigeration plants currently use fluorine-containing volatile organic compounds which are environmentally persistent and have significant global warming potential
Ammonia also used although is toxic and has very strong smell
CO2 is rapidly emerging as a viable alternative
Area of intense activity for variety of applications (large scale refrigeration, automobile air conditioning, heat pumps, domestic use).

19. CO2 Refrigeration Large scale units now in operation.
ASDA distribution centres in Falkirk and Skelmersdale (2003)
Amongst the biggest temperature controlled buildings in the UK (412,000m3)
Nestle Coffee freeze drying plant in Hayes, completed in Jan 2002

20. Chemical Synthesis Fluoropolymer synthesis Dupont $275M facility
Replaces CFCs used previously (now banned by Montreal Protocol)
Initially used for fluorinated
ethylene-propylene and perfluoroalkoxy resins
Easy polymer isolation and drying, and minimal waste
Replacement for halogenated solvents
S.L. Wells amd J. DeSimone, Angew. Chem. Int. Ed., 2001, 40, 518.

21. Would a consumer prefer to purchase a common pharmaceutical product (e
Would a consumer prefer to purchase a common pharmaceutical product (e.g. aspirin) prepared using CO2 as a solvent rather than more harmful VOCs?
How much extra would they be prepared to pay?

22. Conclusion
CO2 already has widespread application with more areas under development
Very favourable profile for consumer applications
Relatively high pressure and energy use may be an issue and needs to be balanced, but can be minimised
Has potential as real green technology of the future, as well as the present
Use and exploitation of CO2 can only increase.