Boosting RuO2 Surface Reactivity by Cu Active Sites over Ru/Cu-SSZ-13 for Simultaneous Catalytic Oxidation of CO and NH3

Catalytic removal of CO from industrial flue gases has been an increasing concern. One attempt is utilizing the tail part of an SCR unit to oxidize abundant CO and trace “slip NH3” synergistically. Herein, Ru/Cu-SSZ-13 was developed to conduct the oxidation of CO and the selective catalytic oxidation of NH3 (NH3-SCO) simultaneously and showed 10 times higher reaction rates than Ru/SSZ-13 on both oxidations. The RuO2 (110) surface was highly active for CO oxidation and NH3 dehydrogenation but would turn insensitive due to the accumulation of adsorbed NO species (NOcus), which derived from the peroxidation during NH3 dehydrogenation. With the assistance of Cu-SSZ-13, generated NOcus could be consumed in an internal SCR route conducted by the activated Cu2+/Cu+ redox cycle, which made NOcus available for the NH3 preferential oxidation rather than the blocked reactive surface. Also, it promoted NH3 transformation on the Cu-SSZ-13 side and boosted the regeneration of Ru-active sites from occupation by NOcus to enable simultaneous CO oxidation. Therefore, the reactivity of RuO2 was boosted after minimizing the interference between the transformation paths of CO and NH3. Furthermore, due to the high NH3-SCO sensitivity of Ru/Cu-SSZ-13, the trace “slip NH3” can be preferentially removed from CO-rich flue gas.