Boosting the NOx reduction and C3H8 oxidation of the Pd-based core-shell TWC in a water-added environment through dispersed treatment

Water molecules are one of the main impurities in automobile exhaust that will affect the efficiency of three-way catalyst (TWC). Therefore, 600d-Pd@Ce/ACH (the dispersed core-shell active site is obtained by 600 °C calcination and loaded with the alkaline-carbonized halloysite support) with great activity and high water-resistance is designed by dispersed treatment and support modification. The result of XPS indicates that 600d-Pd@Ce/ACH with a higher amount of Ce³⁺ and a lower proportion of Pd²⁺ facilitate the TWC activity and water-resistance ability, respectively. On the other hand, the catalyst with a certain intensity of hydroxyl groups can enhance the CO oxidation and whole TWC activity, which can be observed in FTIR analysis. Thus, compared to Pd@Ce/H∗ (the catalyst without modification; the star symbol (∗) indicates that the TWC activity test was conducted in a water-added environment), the T₅₀ of NO_x and C₃H₈ for 600d-Pd@Ce/ACH∗ decreases by 156 °C and 137 °C, respectively. Therefore, this research concludes that the generation of functional groups influences TWC mechanisms, leading to competitive adsorption or improved water resistance. Hence, this research provides a promising approach to improve the water-resistance of the core-shell TWC and verifies the reaction mechanism by XPS and FTIR analysis.