Synthesis of nano-sized Pd/CeO2 three-way catalyst by water-in-oil microemulsion method

Abdul Hadi
Mechanical Engineering Dept. University of Malaya

*Iskandar Idris Yaacob
Mechanical Engineering Dept. University of Malaya

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     Last modified: March 13, 2006

Abstract
ABSTRACT

Nano-sized CeO2 supported Pd catalyst were synthesized by water-in-oil microemulsion technique using cerium nitrate and palladium chloride as the starting materials. Sodium hydroxide was used as precipitating agent, n-octane as the oil phase, HTAB as the surfactant, and n-butanol as the co-surfactant. In this typical procedure, two emulsion solutions containing surfactant, co-surfactant, oil phase and aqueous solution of different reactant were prepared. One of microemulsion contained the mixture of Pd and CeO2 raw material solutions that were mixed at an appropriate ratio. Another contained sodium hydroxide solution. Both solutions were then mixed at room temperature producing the Pd/CeO2 nanoparticles. Structure and properties of the synthesized particles were investigated using X-ray diffractometer (XRD), transmission electron microscopy (TEM), and gas adsorption-desorption analysis. It was found that the crystal structure of synthesized particles was face centered cubic (FCC) with an average crystallite size of about 4 nm. The size of particles investigated using TEM was found to be around 4 to 5 nm and particles had nearly spherical shape. The specific surface area of particles determined using gas adsorption desorption apparatus was found to be about 207 m2/g with BET particle size of about 4.37 nm. In addition, our results showed that the particle size and surface area of the particles could be properly controlled using microemulsions.