LAUSR

Abstract Mixed Ti Si O materials prepared by non-hydrolytic xerogel method have been employed as diluters for nickel oxide and used in the catalytic oxidative dehydrogenation of ethane. These catalysts have been characterized by several physicochemical techniques such as N2 adsorption, XRD, TPR, TEM, HR-TEM, and XPS. Supported nickel oxide catalysts have been reported to be efficient but only if the nature and the amount of support are controlled. In the present article it is shown that highly loaded (80 wt% NiO) nickel catalysts are more efficient when diluted on mixed Ti Si O materials with appropriate Ti/Si ratios than on pure TiO2 and SiO2 diluters. The catalytic results have been explained on the basis of both the crystallite size and the reducibility of NiO crystallites, as a consequence of the interaction between nickel oxide particles and metal oxides diluters. The optimal Ti/Si ratio in the diluter ensures a good dispersion of NiO because Ti4+ sites and/or very small TiO2 crystallites are highly dispersed in the surface of the matrix allowing a close contact with NiO particles. Small NiO crystallites in contact with titania are highly selective to ethylene in the oxidative dehydrogenation of ethane.