variable thermodynamic 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 catalytic combustion, the overriding constraints are robustness and controlled catalyst temperatures over the wide operating range of the engine.