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Supercritical CO2 as a Solvent Media
Environmentally Benign Chemical Synthesis and Catalysis in Liquid and Supercritical Carbon Dioxide (SC-CO2)
A large number of industrial chemical reactions occur in organic solvents which include chlorofluorocarbons, benzene, and carbon tetrachloride-all of which have such environmental downside such as toxicity or damage to the stratosphere ozone layer. Many of these solvents are among the ten most released chemicals to the environment. Supercritical carbon dioxide (SC-CO2) has been identified as a promising environmentally benign solvent. It is an energy conserving, selective and waste reducing alternative to organic solvents. Fast and sensitive organic synthesis can be achieved with high levels of functionality, controllability and energy efficiency. Product separation and fractionation may accompany the reaction, reducing the number of process steps.
The objective of this project is to further evaluate the use of SC-CO2, as a reaction medium for heterogeneous selective oxidation using conventional and "green catalysts" and for hydrogenation of organic compounds that have pharmaceutical applications. The environmental advantages of using SC-CO2 in a closed loop system, are counterbalanced by efforts and expenses associated with the use of high pressure installations. The operational economics of the process and related environmental impact for the use of supercritical fluids as a reaction/separation medium for heterogeneous reactions is being analyzed. Cost and life cycle analysis are used to compare SC-CO2 processes with conventional ones.
Recent Publications:
Oxidation in Supercritical Carbon Dioxide using Clean Oxidants
E. Sahle-Demessie, Michael A. Gonzalez, Julius Enriquez and Qiuming Zhao, Industrial & Engineering Chemistry Research, 39, 4858-4864 (2000).Deposition of Chemicals in Porous Solids using Supercritical Fluid Carriers,
E. Sahle-Demesie, K. Levein, and J. J. Morrell, 1997, CHEMTECH, March, 28, 3 (1998).Fractionation of Glycerides using Supercritical Carbon dioxide,
E. Sahle-Demessie, Industrial & Eng. Chemistry Research, 32, 4906 (1997).Thermal Gradient Fractionation of Glycerides under Supercritical Carbon Dioxide,
J. King, E. Sahle-Demessie, F. Temelli, J. Teel, Journal of Supercritical Fluids. 10, 127-137, (1997).
Contact Information:
Primary Investigators:Dr. E. Sahle-Demessie
(513) 569-7739
sahle-demessie.endalkachew@epa.gov
Dr. Michael Gonzalez
(513) 569-7998
gonzalez.michael@epa.gov
Postal Address:
26 West Martin Luther King Drive
Mail Stop 443
Cincinnati, Ohio 45268