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Title: Influence of cerium precursor on the size and solid solubility of transition metals in combustion synthesized Ce1-xMxO2-δ (M = Cu, Pd) nano crystallites: Enhancement of redox properties and catalytic activity
Authors: Gayen, Arup
Baidya, Tinku
Prakash, A S
Ravishankar, N
Hegde, M S
Issue Date: Jan-2005
Publisher: NISCAIR-CSIR, India
IPC Code: Int. Cl.7 B01J 23/00; C01F 17/00; C01G 3/02; C01G 55/00
Abstract: Two cerium precursors have been employed to synthesize Ce1-xMxO2-δ (M = Cu, Pd) nano-crystalline catalysts by solution combustion method. These nano materials have been characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and BET surface area measurement. Redox behaviour of the catalysts was investigated by temperature-programmed reduction (H2 TPR). Use of ceric ammonium nitrate (precursor A) gives ceria crystallites of size 30-45 nm while cerrous nitrate (precursor B) g ives 10- 15 nm sized crystallites indicating three fold decrease in crystallite size of CeO2. Solid solubility of copper in CeO2 matrix is between 5-10 atom % with precursor A and it increases to 10-15 atom % with precursor B. The crystallite size is between 15-20 nm using B precursor compared to 40-50 nm crystallites with precursor A when Pd was substituted for Ce indicating approximately a two-fold decrease. With precursor A, solid solubility of Pd in ceria is between 3-5 atom % which increases to ̴10 atom % with precursor B. Structural study shows M 2+ ion substitution into CeO2 matrix. The enhancement of solid so lubility coupled with the decrease in crystallite size is associated with an increase in oxygen storage capacity and catalytic activity for CO oxidation by O2 and NO reduction by CO. Such an approach to synthesis of transition metal ion substituted nano CeO2 is leading to catalysts with higher catalytic activity.
Page(s): 34-48
ISSN: 0975-0975(Online); 0376-4710(Print)
Appears in Collections:IJC-A Vol.44A(01) [January 2005]

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