The water-gas shift reaction in sub-critical water: reaction kinetics and modelling
Advancing the chemical engineering fundamentals
Chemical Reaction Engineering: Kinetics & Modelling (T2-2a)
Keywords: water gas shift reaction, sub-critical water
The water-gas shift reaction in sub-critical water: reaction kinetics and modelling
G. Akgül(a), A. Kruse(a), M. Olzmann(b)
(a)Institut für Technische Chemie, Bereich Chemisch-Physikalische Verfahren (ITC-CPV), Forschungszentrum, Karlsruhe/Germany
(b)Institut für Physikalische Chemie, Universität Karlsruhe (TH)/Germany
The Water Gas Shift Reaction (WGSR) that is, the reaction of carbon monoxide and water to produce hydrogen and carbon dioxide, is an important fundamental reaction applied in industry. At accessible industrial temperatures and pressures, its rate is prohibitively low. However, it was shown that the WGSR could be accelerated if water as the reaction medium is used.(1) Water has generally attracted increasing attention as a chemical reaction medium, because its physical and chemical properties can be scaled over a considerable range by changing the temperature and the pressure. At near-critical (200 °C < T < 374 °C, P > 22 MPa) or supercritical conditions (T > 374 °C, P > 22 MPa),(2) it becomes, for instance, a good solvent for weakly polar molecules.
In this contribution, we report on kinetic investigations of the WGSR performed in an excess of water in a flow reactor at a pressure of 23 MPa and temperatures between 230 and 370 °C. The experimental results were analysed in terms of a complex reaction mechanism, and the assumption(3) that formic acid is an intermediate species in the WGSR could be experimentally confirmed. The occurrence of formic acid as an intermediate at hydrothermal conditions is the key to a better understanding of the kinetics and the mechanism of the WGSR.
Additionally, the effects of salts and oxygen were experimentally studied and compared with model calculations.
Literature
[1]Rice, S. F., Steeper, R. R., Aiken, J. D., J. Phys. Chem. A 102, 1998, 2673 – 2678.
[2]Dinjus, E., Kruse, A., J. Phys. Condens. Matter, 16, 2004, 1161 – 1169.
[3]Melius, C. F., Bergan, N. E., Shepherd, J. E., Proc. Combust. Inst. 23, 1990, 217 – 223.
Presented Monday 17, 11:33 to 11:52, in session Chemical Reaction Engineering: Kinetics & Modelling (T2-2a).
