studied different noble metal catalysts for activity in the CO-PROX in hydrogen-rich streams and concluded that Pt on Co-oxide is a highly active catalyst for the reaction. Huang et al. [47, 48] used iridium based catalysts (Ir/CeO2) which exhibited excellent performance in PROX process. Reductive pre-treatment of Ir/CeO2 was found to be beneficial to obtain higher CO oxidation activity at low temperatures.