On the importance of the catalyst redox properties in the N2O decomposition over alumina and ceria supported Rh, Pd and Pt

Rh, Pd and Pt have been supported on gamma-Al2O3, pure CeO2 and La- or Pr-doped CeO2, and these catalysts have been tested for N2O decomposition. The effect of CO and O-2 in the feed has been studied. The characterisation techniques used were Raman spectroscopy, XRD, N-2 adsorption at -196 degrees C. H-2-TPR and TEM. The catalytic activity for N2O decomposition of the noble metals follows the trend Rh > Pd > Pt, and the support affects significantly the activity. For CeO2-containing catalyst, a relationship between N2O decomposition capacity and H-2 reduction of ceria has been found, the easier is the reduction the higher is the catalytic activity. The rate-limiting step of the N2O decomposition mechanism over noble metal/ceria catalysts seems to be the reduction of the catalytic active sites. For Rh catalysts, ceria supports are involved actively in the decomposition of N2O, and all the ceria-based supports improve the catalytic activity of Rh with regard to gamma-Al2O3 due to the redox properties of ceria. The Pd catalysts with pure and doped ceria support showed similar activity, this being higher than that of Pd/gamma-Al2O3. Pt/CeO2 is the most active catalyst among those of Pt, but ceria doping by La or Pr has a negative effect on the activity. The most active catalyst among those prepared in this study is Rh/CeO2(Pr). 2010 Elsevier B.V. All rights reserved.