Design of Cu-Based Ultra-Low Temperature CO and Hydrocarbon Oxidation Catalysts

Advanced combustion technologies offer significant improvement in fuel economy as well as lower NO_x emissions from the nature of low temperature combustion; however, the low exhaust temperature has been a major concern in the removal of hydrocarbon and CO emissions under a tighter regulatory environment.  In the present study, we discovered that cerium zirconium mixed oxide containing copper (CZCu) was more actively converting CO at below 130 °C under simulated diesel exhausts including water and HCs than Pt-based commercial catalyst benchmarked.  However, this catalyst showed poor activity for light HC oxidation, while Pt-Pd/alumina (PtPd/Al) revealed the high performance.  To improve overall activities for both oxidations, we designed the incorporated catalyst system including the CZCu and Pt-Pd/Al for CO and HC oxidations, respectively.  Achieved in this work with the new incorporated system were much lower T50s, the temperatures where 50% of conversions appeared, for CO, light HC and heavy HC oxidations than those by benchmarking counterpart, PtPd/Al.  Although the CZCu consisting of the new catalyst system suffered from significant deactivation upon hydrothermal aging, the incorporated system still showed better oxidation activities than PtPd/Al even after aging.  In addition, the results of the present study revealed that the new catalyst system has a high potential for reducing the amount of noble metals.