variablethermodynamic conditions (inlet pressure and temperature), and variable reactor residence time (space velocity). To provide this flexibility, the catalytic combustor is not generally required to maximize yield or selectivity to a particular product; instead, the catalystis required to provide stability to a combustion process, usually by providing a temperature rise to a fuel/air mixture. For catalyticcombustion, the overriding constraints are robustness and controlled catalyst temperatures over the wide operating range of the engine.