Applied Catalysis A: General 248 (2003) 169–180 Preparation and characterization of In 2 O 3 -TiO 2 and V 2 O 5 /In 2 O 3 -TiO 2 composite oxides for catalytic applications Benjaram M. Reddy ∗ , Ibram Ganesh, Ataullah Khan Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Uppal Road, Hyderabad 500007, India Received 7 January 2003; received in revised form 17 February 2003; accepted 17 February 2003 Abstract In 2 O 3 -TiO 2 (1:13 mole ratio) mixed oxide was prepared by a co-precipitation method with in situ generated ammonium hydroxide and was impregnated with various amounts of V 2 O 5 (4–12 wt.%). The In 2 O 3 -TiO 2 and V 2 O 5 /In 2 O 3 -TiO 2 samples were subjected to thermal treatments from 773 to 1073 K and were investigated by X-ray diffraction, FT-infrared, and BET surface area methods to establish the effects of vanadia loading and thermal treatments on the surface structure of the dispersed vanadium oxide species and temperature stability of these catalysts. Characterization results suggest that the co-precipitated In 2 O 3 -TiO 2 is in X-ray amorphous state and exhibits reasonably high specific surface area. The In 2 O 3 -TiO 2 also accommodates a monolayer equivalent of V 2 O 5 (12 wt.%) in a highly dispersed state. The V 2 O 5 /In 2 O 3 -TiO 2 catalyst is thermally stable up to 873 K calcination temperature. When subjected to thermal treatments beyond 873 K, the dispersed vanadium oxide selectively interacts with In 2 O 3 portion of the mixed oxide and forms InVO 4 compound. The remaining TiO 2 appears in the form of anatase or rutile phase. These samples were evaluated for one step synthesis of 2,6-dimethylphenol from cyclohexanone and methanol mixtures in the vapour phase at normal atmospheric pressure. The 12% V 2 O 5 /In 2 O 3 -TiO 2 catalyst exhibits good conversion and product selectivity among various samples investigated. © 2003 Elsevier Science B.V. All rights reserved. Keywords: Titanium oxide; Indium oxide; Mixed oxide; In 2 O 3 -TiO 2 ;V 2 O 5 ; Dispersion; Acid–base properties; Redox properties; Cyclohexanone; Methanol; 2,6-Dimethylphenol 1. Introduction Titania has been widely employed as a support as well as catalyst for variety of applications [1]. The vanadium-titanium oxides are the basic com- ponents of industrial catalysts for selective catalytic reduction (SCR) of nitrogen oxides, selective oxida- tion of various hydrocarbons, and ammoxidation of N-heteroaromatic compounds [2–5]. In particular, tita- ∗ Corresponding author. Tel.: +91-40-2717-5406; fax: +91-40-2716-0921. E-mail addresses: bmreddy@iict.ap.nic.in, mreddyb@yahoo.com (B.M. Reddy). nia anatase has been extensively used for several pho- tocatalytic reactions for elimination of many organic pollutants from waste-waters [6,7]. Titania-based cat- alysts were also employed for HCN and COS hydroly- sis, olefin epoxidations [8], and precious metal (Pt, Rh or Ru) or Ni-impregnated titania for Fischer–Tropsch synthesis [9]. The TiO 2 has also been used as an oxy- gen sensor to monitor automobile engine performance [10]. Numerous other reactions such as oxidation of H 2 S to SO 2 , dehydration of alcohols, isomerisation, and alkylation have also been studied by employing TiO 2 catalysts [1,10,11]. However, there are some disadvantages associated with TiO 2 which include low specific surface area, poor thermal stability, poor 0926-860X/$ – see front matter © 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0926-860X(03)00157-1