On the Catalytic Activity of Cobalt Oxide for the Steam Reforming of Ethanol Simonetta Tuti Æ Franco Pepe Received: 24 October 2007 / Accepted: 23 November 2007 / Published online: 12 December 2007 Ó Springer Science+Business Media, LLC 2007 Abstract The paper presents an investigation on the catalytic activity for the ethanol steam reforming of Co 3 O 4 oxidized, reduced and supported on MgO, and of CoO in MgO solid solution. Only samples containing metallic cobalt are found to be active for reforming reaction. H 2 - TPR characterization of aged samples shows that reaction mixture oxidizes a small fraction of metallic cobalt to Co +2 . A distinct role of Co +2 and Co 0 in the reaction is enlightened. Keywords Ethanol steam reforming  Hydrogen  Cobalt oxide  Supported cobalt catalyst 1 Introduction The progressive depletion of fossil resources and the need of green gas emissions control, have strongly focused the attention on the development of alternative energy sources. The bio-ethanol derived from biomasses is a good source because it is easy to transport, biodegradable, and low in toxicity and it could be directly used in steam reforming reaction, SRR. The SRR of ethanol CH 3 CH 2 OH + 3 H 2 O ? 6H 2 +2 CO 2 is able to produce 6 mole of H 2 per mole of ethanol (H 2 /EtOH = 6). Recent reviews [1, 2] reported extensive comparisons between catalytic properties of the most studied catalysts for SRR of ethanol, such as oxides, noble metal-based catalysts (Pt, Rh, Ru), nickel-based catalysts, and cobalt-based catalysts. Required performances include the production of CO-free hydrogen, and low cost and durability of the catalyst. Oxide-supported cobalt catalysts exhibit a good performance in ethanol SRR, with ethanol conversion of 90–100%, high selectivity to H 2 (60–75%), and low production of CO [3–13]. The non desired reac- tions may produce methane, ethane, ethene, acetone, and other C 2 and C 3 -hydrocarbons. The largest hydrogen yields in the temperature range 400–500 °C were found on Co/Al 2 O 3 (H 2 67–75%) [3, 12], Co/ZnO (H 2 73–75%) [4, 7] and Co 3 O 4 (H 2 73%) [8, 14]. However, pure Co 3 O 4 has been scarcely investigated with respect to catalytic properties. The high selectivity of Co/ Al 2 O 3 was ascribed to the suppression of the methanation of CO and of the EtOH decomposition [3]. The CO selectivity is 0–20%, and depends on reaction temperature, material composition [3, 7, 9, 11], and ethanol/water molar ratio [12]. A significant decrease in CO formation is obtained by increasing the cobalt content up to 18 w/w% [9]. Co/ZnO catalyst prepared from Co 2 (CO) 8 [7] and pure Co 3 O 4 [8] show high selectivity for CO-free hydrogen production at temperature as low as 350–400 °C. Over these samples, the only products obtained are H 2 , CH 4 and CO 2 . The polymerization processes of acetaldehyde [15] or CH x species formed during reaction, originate large coke deposition on the surface which is the main cause of deac- tivation for all cobalt catalyst [4, 6, 7, 11, 13]. The amount and the nature of the deposited carbon (17–24 w/w% after 9 h of SSR at 400 °C[6]) depends mainly on the support, and on the reaction temperature. Co/Al 2 O 3 catalysts deposit a large amount of coke that causes a progressive decay during few hours on stream [6, 13]. Co/MgO has been found more stable than Co/Al 2 O 3 for the lesser coke formation due to a lower acidity of the support [13]. Even on Co/CeO 2 S. Tuti  F. Pepe (&) Dipartimento di Ingegneria Meccanica e Industriale and Centro Interdipartimentale per la Didattica della Chimica, Universita ` di Roma Tre, Via della Vasca Navale 79, 00146 Rome, Italy e-mail: pepe@uniroma3.it 123 Catal Lett (2008) 122:196–203 DOI 10.1007/s10562-007-9370-8