Effect of rare earths (La, Pr, Nd, Sm and Y) on the methane combustion over Pd/Ce-Zr/Al2O3 catalysts

The effects of rare earths (La, Pr, Nd, Sm and Y) addition to Pd/Ce-Zr/Al2O3 catalyst have been investigated. The supported Pd catalysts are characterized by BET, XRD, XPS, TEM, TPR, TPO and TPSR techniques. Activity tests in methane combustion show that the addition of Y or Sm obviously improves the catalytic activity of Pd/Ce-Zr/Al2O3 catalyst, and the Pd/Ce-Zr-Y/Al2O3 shows the highest catalytic activity and thermal stability. The addition of Y to Pd/Ce-Zr/Al2O3 inhibits the site growth and decomposition of PdO particles and improves the reduction-reoxidation properties of the active PdO species, which increases the catalytic activity and thermal stability of the Pd/Ce-Zr/Al2O3 catalyst. (c) 2005 Elsevier B.V. All rights reserved.