Ni(II)–Mg(II)–Al(III) catalysts for hydrogen production from ethanol steam reforming: Influence of the activation treatments Adriana Romero a , Matı ´as Jobba ´ gy b , Miguel Laborde a , Graciela Baronetti a , Norma Amadeo a, * a Laboratorio de Procesos Catalı´ticos, Departamento de Ingenierı´a Quı´mica, Facultad de Ingenierı´a Ciudad Universitaria, (1428) Buenos Aires, Argentina b INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabello ´n II, Ciudad Universitaria, (1428) Buenos Aires, Argentina 1. Introduction During the last centuries, human civilization solved the energy supply problem mainly on the bases of fossil sources of carbon and hydrocarbons and the associated technologies. The XXI century scenario claims for alternative sources and technologies. Most of the chemical based alternatives consider hydrogen as an efficient energetic vector since it directly transforms chemical reactions into electric energy by means of fuel cells technology, releasing steam as the only product. However, hydrogen non-contaminant character depends on the nature of the raw material used as source. In this sense, steam reforming of ethanol, obtained from biomass, offers a true green alternative for H 2 production, due to its inherent renewable character, low toxicity (unlike methanol) and the fact that it can be obtained virtually sulphide-free [1,2]. Ethanol has relatively high hydrogen content and in presence of water, is capable of producing 6 mol of H 2 per mol of ethanol: C 2 H 5 OH þ 3H 2 O ! 2CO 2 þ 6H 2 (1) From a thermodynamic viewpoint, reforming reaction is highly favourable, but it competes with multiple side reactions [1,3] and in general, the outflow from the reactor contents a wide range of liquids and gaseous products. Different catalytic systems have been proved to be effective with variable hydrogen selectivity’s [1– 11]. Ni catalysts have been widely utilized in reforming of hydrocarbons because it promotes the rupture of the C–C bonds, achieving high activity [11–14]. Noble-metal-catalysts (Rh, Pt, and Pd) also present high activity and selectivity [9], however their high cost limits their high-scale-use, in contrast to nickel based ones. In order to prevent undesired carbon formation, ternary Ni(II)–Mg(II)–Al(III) oxides were proposed, where the presence of Mg(II) disfavour this undesired product [15]. Concerning to the preparation of such catalysts, many reports suggested the use of carbonate layered double hydroxides (LDHs) as suitable precursors, since such compounds present, after an activation treatment, Ni metal nanoparticles highly dispersed within a high surface area oxidic matrix [16,17]. Mixed oxides obtained by thermal decomposition of defined crystalline pre- cursors offer a more rational and reproducible procedure. Melo and Morlane ´s [16] and Dung et al. [18] studied the effect of the thermal treatments on the performance of the catalysts obtained from LDH precursor. They used hydrocarbon steam reforming and acetonitrile hydrogenation, respectively, as reaction test. In this paper we analyze the influence of the thermal treatments on the performance of the same catalyst using ethanol steam reforming as reaction test and also considering the effect of direct reduction of the precursor on the catalyst performance. The aim of this work is to explore the chemical and structural evolution of a crystalline Ni(II)–Mg(II)–Al(III) LDH under different Catalysis Today 149 (2010) 407–412 ARTICLE INFO Article history: Available online 29 July 2009 Keywords: Bioethanol Hydrogen production LDH Ni catalyst Reforming ABSTRACT The effect of the Ni(II)–Mg(II)–Al(III) layered double hydroxide (LDH) activation conditions over the surface and bulk composition and the catalytic performance in ethanol steam reforming (ESR) is studied. Ternary oxides were prepared by thermal decomposition of LDHs synthesized using the homogeneous precipitation method with urea. Catalyst precursor is submitted to two different activation treatments: calcinations at 400, 500, 600 and 700 8C with subsequent reduction at 720 8C, or direct reduction at 720 8C. The samples were characterized by sorptometry, H 2 chemisorption, ICP chemical analysis, thermogravimetric analysis, X-ray diffraction, X-ray photoelectronic spectroscopy and temperature programming reduction. The catalysts obtained by calcination at 600 8C and then reduction at 720 8C and those directly reduced at 720 8C showed the better performance in ESR. The precursor submitted to a proper thermal treatment develops, through a decoration-demixing process, a Ni(II)-poor spinel-type shell onto NiO domains. Published by Elsevier B.V. * Corresponding author. Fax: +54 11 4576 3241. E-mail addresses: norma@di.fcen.uba.ar, normaamadeo@yahoo.com.ar (N. Amadeo). Contents lists available at ScienceDirect Catalysis Today journal homepage: www.elsevier.com/locate/cattod 0920-5861/$ – see front matter . Published by Elsevier B.V. doi:10.1016/j.cattod.2009.05.026