Structure-sensitivity of alumina supported palladium catalysts for N2O decomposition.

• Pd is a potential catalyst for end-of-pipe treatment of N 2 O. • Removal of chemisorbed H 2 O on Al 2 O 3 leads to improved Pd dispersion. • Increased dispersion leads to increased activity for N 2 O decomposition. • Co-fed reductant reduces N 2 O total decomposition temperature from 550 to 350 °C. • Benefit of well-dispersed Pd outweighs poisoning effect of residual chloride. The catalytic activity of Pd/γAl 2 O 3 for N 2 O decomposition was found to be highly dependent on the preparation methodology and the number of reaction cycles. Chloride species on the surface of a 2.6 wt. % Pd-Al 2 O 3 catalyst prepared by wet impregnation were identified as inhibiting the activity. Multiple reaction cycles were shown to remove these species, and a subsequent increase in activity was observed; 10.3 mol N2O h−1 kg cat −1 in the first use, increased to 28.7 mol N2O h−1 kg cat −1 on the fourth use both at 550 °C. Additionally, removal of physisorbed water from the support prior to metal deposition increased the thermal stability of Pd nanoparticles and increased the catalyst activity. Catalysts were subsequently prepared using a deposition technique with an increased concentration of Cl- ions resulted in increased Pd-Cl species in the final catalyst and the catalytic activity was consequently increased due to the improved control of Pd particle size. [ABSTRACT FROM AUTHOR]