Abstract: Several air inputs are typically required in removal of carbon monoxide from a fuel reformate, particularly when using the reformate in a PEM (polymer electrolyte membrane) fuel cell. Control can be greatly simplified by distributing the air or oxygen among the inlets in a fixed ratio using a fixed dimension flow path, such as sized orifices, conduits, and the like, and selecting the total oxygen input to the system based on the operating state of the system and its operating map.