(99e) Reductant Induced Redox Behavior of Atomically-Dispersed Palladium in Pd-CHA
- Conference: AIChE Annual Meeting
- Year: 2022
- Proceeding: 2022 Annual Meeting
- Group: Catalysis and Reaction Engineering Division
- Time: Monday, November 14, 2022 - 1:50pm-2:10pm
Upon binding, NO facilitates the activation of one of the water molecules coordinated to Pd, forming the key intermediate HONO, which subsequently disproportionates to NO, NO2, and H2O as shown in Fig.1(a). The reduced form of Pd serves as a strong storage site for NO and the mechanism is favorable under reaction conditions as shown in Fig.1(b).
We find that active site transformation in the presence of CO is facilitated by both oxygen and water forming Pd-hydroperoxyl, which leads to enhanced NO uptake at low temperature. Consistent with our DFT results, the experiments shown in Fig.1(c) also confirm that CO does not change the NOx uptake under dry condition whereas NOx uptake increases when both water and oxygen are present as shown in Fig.1(d). Finally, our results suggest that the presence of both water and CO is required to deactivate the catalyst.