Many workers [46-71] studied about preferential oxidation of CO over noble metal based catalysts. Generally, Pt, Rh, Ru and Ir based catalysts fall in this category. The noble metal based catalysts are conventionally used for the COPROX. Hulteberg et al. [46] 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.