Combustion of volatile organic compounds over supported manganese oxide: Influence of the support, the precursor and the manganese loading Fabiola N. Aguero a , Alberto Scian b , Bibiana P. Barbero a , Luis E. Cadu ´s a, * a Instituto de Investigaciones en Tecnologı ´a Quı ´mica (INTEQUI), UNSL, CONICET, Casilla de Correo 290, 5700 San Luis, Argentina b Centro de Tecnologı ´a de Recursos Minerales y Cera ´mica (CETMIC), Camino Parque Centenario y 506, 1897 Manuel B. Gonnet, Buenos Aires, Argentina Available online 7 January 2008 Abstract Manganese oxide catalysts supported on Al 2 O 3 and Mg–Al 2 O 3 composite were prepared from two different precursors, manganese acetate and manganese nitrate, with two manganese loadings. Catalytic performance was evaluated in ethanol combustion, which is a volatile organic compound used as solvent in print industries and a potential fuel for vehicles. The most active and selective catalysts to total oxidation were those prepared from manganese acetate. By means of a wide physicochemical characterization by X-ray diffraction (XRD), X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), Raman spectroscopy, scanning electron microscopy (SEM), and specific surface area measurements, it was found that the best catalytic performance was obtained when manganese oxide species are highly dispersed on the catalyst surface. The formation of these surface species depends mainly on the manganese precursor and also on the support and the manganese loading. # 2007 Elsevier B.V. All rights reserved. Keywords: Supported manganese oxide catalysts; Characterization; Complete oxidation 1. Introduction Volatile organic compounds (VOCs) and NO x are the main contribution to the atmospheric pollution. When great volumes of gases with low concentrations of VOC have to be treated, the catalytic oxidation is preferred. Platinum and palladium are the most commonly used catalysts [1]. However, metal oxides such as manganese oxides have demonstrated a catalytic activity as good as the one of the noble metals. Moreover, they are a cheaper alternative and have a higher sinterised resistance [2]. Considering that the main sources of VOC are vehicles and industries that use solvents, it is important to evaluate the catalytic performance in ethanol combustion, due to two main reasons: (i) this is a potential fuel for vehicles and (ii) with ethyl acetate, they are both widely used solvents. Industrial application of VOC catalytic combustion process involves great volumes of gases therefore, it is essential to deposit the catalyst on a structured support to avoid high-pressure drops. The most studied supports are monoliths, which are usually made of ceramic or metal materials, covered with a carrier, alumina, that acts as a support of the active phase [3]. It is widely known that deposition of a metallic oxide on an inert support leads to a catalyst with better catalytic performance than the oxide as a bulk catalyst. In part, this is due to the high surface area that supports present. However, the main reason from the catalytic behaviour point of view is the oxide specie type generated on the surface, which depends on the dispersion of the active phase and its interaction with the support. In the present work, catalysts based on manganese oxides supported on alumina and Mg–Al 2 O 3 composite are studied. These oxides can be used as carriers for monolithic catalysts. In addition, the influence of the support nature (composition, surface acidity, etc.), the precursor nature (organic, inorganic) www.elsevier.com/locate/cattod Available online at www.sciencedirect.com Catalysis Today 133–135 (2008) 493–501 * Corresponding author. Fax: +54 2652 426711. E-mail address: lcadus@unsl.edu.ar (L.E. Cadu ´s). 0920-5861/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.cattod.2007.11.044