Journal of Catalysis 240 (2006) 245–257 www.elsevier.com/locate/jcat Synthesis, characterisation, catalytic activity and structural stability of LaCo 1−y Fe y O 3 ± λ perovskite catalysts for combustion of ethanol and propane Nora A. Merino a , Bibiana P. Barbero a , Patricio Ruiz b , Luis E. Cadús a,∗ a Instituto de Investigaciones en Tecnología Química (INTEQUI), UNSL-CONICET, Casilla de Correo 290, 5700 San Luis, Argentina b Université Catholique de Louvain, Place Croix du Sud 2, Boite 17, 1348 Louvain la Neuve, Belgium Received 7 February 2006; revised 24 February 2006; accepted 26 March 2006 Abstract LaCo 1−y Fe y O 3 perovskite-type oxides with y = 0.1, 0.3, and 0.5 were prepared by the citrate method and characterized by X-ray diffrac- tion (XRD), BET surface area measurement (SSA), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), and Mössbauer spectroscopy. With this preparation method, a good inclusion of the substituting cation in the B-site is reached, maintaining the rhombohedral crystalline structure, modifying the volume of the unit cell, and weakening the B–O bond. This likely affects the capacity and the mechanism of oxygen supply or the redox behavior. At high iron content, Fe 4+ could exist. Surface enrichment in lanthanum was observed on XPS. The singularity observed in the improvement of the catalytic activity for y = 0.1, in both propane and ethanol combustion, could be explained by the electronic complexity introduced by iron in the perovskite conductor characteristics.  2006 Elsevier Inc. All rights reserved. Keywords: Perovskites; Cobalt; Iron; Citrate method; Catalytic oxidation; Ethanol; Propane 1. Introduction ABO 3 perovskite-type oxides, whose main characteristic is a well-defined structure, have demonstrated to be excellent cat- alysts for volatile organic compound (VOC) combustion [1,2]. Both A and B cations can be partially substituted, leading to a A 1−x A ′ x B 1−y B ′ y O 3±λ general formula. The partial substitution of A ′ for A of different oxidation states leads to the formation of vacancies of the crystalline bonds and also to stabilization of unusual oxidation states of the B cation [2]. The B partial substitution by a B ′ cation can promote changes on both the re- dox ion couples and the active sites, as well as on the stability of the crystalline structure [3], even at high temperatures. By definition, the perovskite structure functions as a host structure that, according to the substituting cations, can exhibit different semiconductor behaviors. * Corresponding author. Fax: +54 2652 426711. E-mail address: lcadus@unsl.edu.ar (L.E. Cadús). The preparation method is important both in defining suit- able textural characteristics for catalysis and in achieving phases of great purity. The literature describes numerous syn- thesis methods, most of which involve synthesizing materials for applications other than catalysis and allow incorporation of cations into the functional perovskite structure due to the high calcination temperatures used. Several techniques have been developed to address the prob- lem of perovskite purity; the most commonly used of these is the sol–gel citrate method [4]. This method makes it possible to obtain catalysts of high surface area, but it has the draw- back of rather rapid sintering depending on the temperature. Other methods also have been used, including that reported by Kaliaguine et al. [5], who synthesized LaCoO 3 and LaCoFeO 3 perovskites by a mechano-synthesis method involving mixing the reactants using additives. Recently, using the citrate method and carefully controlling the synthesis parameters, we synthesized La 1−x Ca x CoO 3 ± λ perovskites with appropriate texture and excellent catalytic 0021-9517/$ – see front matter  2006 Elsevier Inc. All rights reserved. doi:10.1016/j.jcat.2006.03.020