Selective dehydration of 4-methylpentan-2-ol to 4-methylpent- 1-ene has been investigated over SiO, supported CeO2 and CeZri O nanocomposite oxides in the vapour phase under normal atmospheric pressure. The investigated supported nano-oxides were synthesized by a co-precipitation method from ultrahigh dilute aqueous solutions of nitrate precursors and colloidal silica. Physicochemical characterization was achieved by X-ray powder diffraction, Raman spectroscopy, high-resolution transmission electron microscopy and BET surface area techniques. XRD measurements revealed the formation of nanosized cubic crystallites of Ce02 and Ce0.75Zr0.25O2 in CeO2/SiO2 and CeZr1-xO2/SiO2 catalysts, respectively. The Raman studies provided evidence for the formation of oxygen vacancies in both the catalysts. The HRTEM results revealed that SiO2 acts as an inert support to stabilize the formed nanosized cubic crystallites of CeO, and Ce-Zr-oxides (similar to 3-5 nm) in case of CeO2/SiO2 and CexZr1-xO2/SiO2 samples, respectively. The conversion of 4-methylpentan-2-ol was increased to some extent when Ce02 was dispersed over SiO,. After incorporation of Zr4+ to CeO2/SiO2, the conversion was found to increase to a greater extent. The selectivity of the desired product 4-methylpent- I -ene was observed to be highly dependent on the reaction temperature. (c) 2007 Elsevier B.V. All rights reserved.