Journal of Sol-Gel Science and Technology, 2, 431-435 (1994) © 1994 Kluwer Academic Publishers, Boston. Manufactured in The Netherlands. Alumina-Titania Oxides: Synthesis and Characterization Code: DP25 J.A. MONTOYA, J.M. DOMINGUEZ, J. NAVARRETE AND I. SHIFTER Inst. Mexicano del Petroleo, ICA, Apdo. Postal 14-805, Mexico D.E 07730 T. VIVEROS Area de lngenieria Quimica, UAM-lztapalapa, Apdo. Postal 55-534, Mexico D.E 09340 D. CHADWICK AND K. ZHENG Dept. of Chemical Engineering, Imperial College, London SW7 2BY, UK Abstract. Alumina-titania mixed oxides with nominal atomic ratios A1/Ti = 25 and 2 have been synthesized by cohydrolysis of Al(OsecBu)3 and Ti(OBu)4. The oxides were amorphous at 500°C, showing only short range order. Ti was incorporated in alumina in a well dispersed way creating a true A1/Ti mixed oxide. The strength of surface acid sites and specific surface areas were increased at the higher Ti content. The TiO2 anatase phase was avoided and futile was formed directly at 900°C. Keywords: mixed oxides, synthesis, characterization, alumina-titania 1. Introduction 2. Experimental The A1203-TiO2 system has shown potential applica- tion as a support of HDS catalysts (1, 2) and the influ- ence of different preparation methods over structural, acidic and catalytic properties has been studied (3, 4). In this system, textural, structural and surface prop- erties of A1203 are modified by the incorporation of TiOz creating new acidic surface sites. It seems that the method of TiO2 incorporation plays an important role in the nature of the final mixed oxide. The sol-gel method provides the route to obtain a homogeneous distribution of components in a solid material. The aim of this work is to use this method to synthe- size a binary mixed oxide of A1 and Ti, which could be suitable to use as a support material for catalysts. For this case two different oxide compositions, with A1/Ti atomic ratios of 2 & 25, were prepared. The thermal evolution, structure, surface composition, surface acid- ity and morphology have been investigated. 2.1. Sample Preparation The samples were synthesized by the cohydrolysis of the mixture formed by aluminum tri-sec-butoxide (ATSB) and titanium (IV) butoxide (TTB) which were purchased from Aldrich. The ATSB and TTB (in or- der to have A1/Ti = 25 and 2.0, ATL and ATH samples respectively) were added to a glass reflux system where isopropanol had previously been added and maintained under vigorous stirring at room temperature. The co- hydrolysis was carried out adding water in a molar ratio water/ATSB + TTB = 30 (in both cases) mixed with HNO3 in a molar ratio HNOa/ATSB + TTB = 0.2. The transparent gels were aged for 24 hours. They were dried passing an air stream through the reactor and the alcohol was collected in a ice cooled trap. Finally, the samples were carefully calcined in an air flow under the following program: the samples were heated from room temperature to 120°C at a rate of