Elevated Pressure Thermal Experiments and Modeling Studies on the Water-Gas Shift Reaction

The water-gas shift reaction influences the chemistry between the postcombustion gases of a rocket and the rocket's graphite nozzle. The rocket's operating pressures (70-600 atm) exceed those for existing water-gas shift reaction data, and further study of the chemistry under similar conditions is essential for optimum rocket design. To investigate chemical kinetic effects at the pertinent pressure and temperature regime, experiments were performed using the University of Illinois at Chicago high-pressure shock-tube facility with experimental temperatures ranging from 1200-2100 K and pressures ranging from 194-490 atm with reaction times averaging 1.17 ms. Initial mole fractions of H 2 O and CO were varied from 115-983 ppm (0.0002-0.003 mol/L). The experimental data have been compared with predictions from a comprehensive model for synthesis gas (CO/H 2 /CO 2 ) combustion and a reduced four-step model with the chemistry relevant to the water-gas shift reaction. The rate coefficients at our elevated pressure and temperature conditions were found to be pressure independent when compared with prior lower temperature 1 atm measurements.