Nearcritical Water as a Reaction Solvent

EPA Grant Number: R828130
Title: Nearcritical Water as a Reaction Solvent
Investigators: Eckert, Charles A. , Brown, James , Bush, David , Griffith, Kris , Hallett, Jason P. , Lesutis, Heather , Liotta, C. L. , Nolen, Shane A. , Pollet, Pamela , Smith, Griffin , West, Kevin
Current Investigators: Eckert, Charles A. , Liotta, C. L.
Institution: Duke University
EPA Project Officer: Karn, Barbara
Project Period: June 1, 2000 through June 30, 2003
Project Amount: $397,910
RFA: Technology for a Sustainable Environment (1999) RFA Text |  Recipients Lists
Research Category: Sustainability , Pollution Prevention/Sustainable Development


Very hot water, 250-350?C, offers exciting possibilities as a benign solvent for the synthesis of organic chemicals and as a vehicle for pollution prevention. As water is heated near its critical region, the fluid expands and takes on several useful properties. It becomes similar to acetone in density and dielectric constant, and as such dissolves both salts and organic chemicals, offering the possibility to run aqueous/organic reactions homogeneously. Further, the inevitable separation following the reaction becomes very simple? merely cooling the mixture will generally cause the organic chemicals to come out of solution. The organic products are then easily decanted. More importantly, as the temperature is increased, the dissociation constant for water, KW, goes up by several orders of magnitude, so that the water itself is a source of both hydronium and hydroxide ions which can act to catalyze reactions. Since no base or acid catalysts need to be added, this avoids subsequent neutralization and salt disposal, dramatically reducing waste byproducts. Studies to date have already demonstrated the potential of this nearcritical water for acid catalyzed reactions, such as Friedel-Crafts alkylations and acylations. This proposal addresses: 1) nearcritical water as a benign replacement solvent for harmful organic chemicals; 2) a much wider range of synthetic opportunities by acid and base catalysis; 3) achievement of carbon-carbon bond formation; 4) driving reactions to higher conversion; 5) hydrolysis and other condensation reactions; 6) utilizing unique phase behavior to achieve difficult separations; 7) preparation of information necessary to reapply techniques to design of sustainable industrial-scale applications.


We will employ a high-pressure high-temperature windowed variable volume view cell constructed in our laboratory to obtain a clear knowledge of the phase equilibria in nearcritical water. We will use high-temperature titanium reactors to explore the kinetics of reactions in nearcritical water. Existing methods for phase equilibrium experiments and analysis will be extended to the special case of nearcritical water, with subsequent development of mathematical models for prediction and design. This information is necessary to facilitate the industrial-scale design of commercial processes.

Expected Results:

As a result of this work, nearcritical water processes will be developed that have the potential of replacing environmentally undesirable solvents and eliminating many hundreds of millions of tons a year of waste. These processes will not only be environmentally superior, but will also offer improved economics for increased competitiveness.

Publications and Presentations:

Publications have been submitted on this project: View all 33 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 10 journal articles for this project

Supplemental Keywords:

green chemistry, alternatives, organics, environmental chemistry, engineering, modeling., RFA, Scientific Discipline, Sustainable Industry/Business, Chemical Engineering, Sustainable Environment, Environmental Chemistry, cleaner production/pollution prevention, Technology for Sustainable Environment, Environmental Engineering, reaction solvent, hydrolysis, carbon carbon bond, cleaner production, environmentally benign solvents, carbon bond formation, alternative materials, nearcritical water, innovative technology, organic chemicals, pollution prevention, source reduction, hydroxide ions

Progress and Final Reports:

Final Report