Paper Title
NANO-SIZED COBALT OXIDE SUPPORTED ON Al2O3 AND SiO2 FOR PURIFICATION PROCESSES-INFLUENCE OF THE SUPPORT

Abstract
Abstract - Co3O4 nano-sized particles were supported on the silica or alumina by one-step hydrothermal method and impregnation. They werecharacterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction (TPR). The catalytic performance was examined in the complete oxidation of n-hexane and methane and preferential CO oxidation (PROX process). Finely divided weakly interacting cobalt oxide particles are formed on the surface of the silica supported catalyst prepared by hydrothermal method. In addition to the phase of Co3O4, a superficial Co-Al spinel-like phase is formed on the alumina surface of the catalystsregardless of the method of preparation. The higher catalytic activity of the sample supported on SiO2 is related to the more accessible active sites, higher bulk oxygen mobility and the facile formation of highly active oxygen species. The lower activity of the alumina supported catalyst is attributed to the formation of the inactive spinel-like phases on the surface. It was observed that all samples show very low activity in methane oxidation. The most active sample in the PROX reaction areCo-SiO2-I and Co-Al2O3-HT. This could be related to the existence of easy reducible Co3O4 and the presence of Co2+.ions on the catalytic surface. Co2+ ions could be sites for oxygen adsorption and formation of active oxygen species. Keywords - Supported Cobalt Oxide Catalysts, VOS Oxidation, PROX Process