Tuning the Interaction between Platinum Single Atoms and Ceria by Zirconia Doping for Efficient Catalytic Ammonia Oxidation.

Aiming at the development of an efficient NH oxidation catalyst to eliminate the harmful NH slip from the stationary flue gas denitrification system and diesel exhaust aftertreatment system, a facile ZrO doping strategy was proposed to construct Pt/CeZrO catalysts with a tunable Pt-CeO interaction strength and Pt-O-Ce coordination environment. According to the results of systematic characterizations, Pt species supported on CeZrO were mainly in the form of single atoms when ≥ 0.7, and the strength of the Pt-CeO interaction and the coordination number of Pt-O-Ce bond (CN) on Pt/CeZrO showed a volcanic change as a function of the ZrO doping amount. It was proposed that the balance between the reasonable concentration of oxygen defects and limited surface Zr-O species well accounted for the strongest Pt-CeO interaction and the highest CN on Pt/CeZrO. It was observed that the Pt/CeZrO catalyst exhibited much higher NH oxidation activity than other Pt/CeZrO catalysts. The mechanism study revealed that the Pt species with the stronger Pt-CeO interaction and higher CN within Pt/CeZrO could better activate NH adsorbed on Lewis acid sites to react with O thus resulting in superior NH oxidation activity. This work provides a new approach for designing highly efficient Pt/CeO based catalysts for low-temperature NH oxidation.