Synthesis, structure and three way catalytic activity of Ce1-xPtx/2Rhx/2O2-δ (x=0.01 and 0.02) nano-crystallites:: Synergistic effect in bimetal ionic catalysts

Bimetal ionic Ce1-xPtx/2Rhx/2O2-delta (x = 0.01 and 0.02) catalysts have been synthesized by a single step solution combustion method. CO and C2H4 oxidation and NO reduction activities of the bimetal ionic catalysts are compared with mono-metal ionic Ce1-xPtO2-delta (x = 0.01 and 0.02) and Ce1-xRhxO2-delta (x = 0.01 and 0.02) catalysts. X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) studies show incorporation of Pt2+ and Rh3+ ions in CeO2 lattice. Low temperature hydrogen uptake at 0 degrees C and below over bimetal ionic catalyst shows enhanced redox property over the corresponding mono-metal ionic analogues. The TOF for CO oxidation over Ce0.99Pt0.005Rh0.005O2-delta is 0.035 s(-1) at 120 degrees C, compared to 0.003 s(-1) over Ce0.99Pt0.01O2-delta and 0.035 s(-1) over Ce0.99Rh0.01O2-delta at 135 degrees C. Enhanced catalytic activity of Ce1-xPtx/2Rhx/2O2-delta (x = 0.01) bimetal ionic catalysts compared to mono-metal ionic catalysts, Ce1-xPtxO2-delta and Ce1-xRhxO2-delta, is attributed to synergism brought about by the easy reduction of Rh3+ ion by Pt2+ ion. (c) 2006 Published by Elsevier B.V.