Cu–Zn–Al hydrotalcites as precursors of catalysts for the production of hydrogen from methanol U. Costantino a, * , F. Marmottini a , M. Sisani a , T. Montanari b , G. Ramis b , G. Busca b , M. Turco c , G. Bagnasco c a CEMIN, Centro di Eccellenza sui Materiali Innovativi Nanostrutturati, Dipartimento di Chimica, Universita ` di Perugia, Italy b Dipartimento di Ingegneria Chimica, Universita ` di Genova, Italy c Dipartimento di Ingegneria Chimica, Universita ` Federico II, Napoli, Italy Abstract The possibility of a wide use of hydrogen as fuel of proton exchange membrane fuel-cells forces to the development of selective catalytic materials for the oxidative steam reforming of methanol (OSRM) to produce H 2 essentially free from CO. Cu/ZnO/Al 2 O 3 catalysts of OSRM process have been obtained from hydrotalcite-like precursors with nominal formula Cu 1x y Zn y Al x (OH) 2 (CO 3 ) x /2 (x = 0.23 – 0.42, y = 0.31 – 0.58) and prepared by homogeneous precipitation from metal chlorides solutions in the presence of urea. The catalysts were obtained after thermal decomposition of the hydrotalcites at 450 -C, followed by in situ reduction with H 2 . X-ray powder diffraction (XRPD) patterns of the precursors showed the presence of the hydrotalcite phase with minor amounts of a Zn-rich paratacamite phase (Cu 2x Zn x (OH) 3 Cl) whose amount increases with increasing Cu content. XRPD patterns of thermally treated samples show only the lines of CuO and ZnO phases; Al 2 O 3 and/or aluminates may be present as amorphous phases. The BET surface areas of the samples are in the range 110–220 m 2 g  1 and increase with increasing Al content. The catalytic activity in the OSRM process is appreciable from about 200 – 250 -C and methanol conversions up to 90 – 95% are obtained at temperatures of 300 – 400 -C. Hydrogen is the main product, and its yield reaches values up to 2.7 mol/mol of methanol. Carbon monoxide content is under the detection limit (500 ppm) of the detector. D 2005 Elsevier B.V. All rights reserved. PACS: -81.05Zx Keywords: Hydrotalcites; Cu/ZnO/Al 2 O 3 catalysts; H 2 production; Methanol reforming 1. Introduction Fuel cells with proton exchange membranes (PEMFCs) are considered one of the most interesting alternatives to the traditional internal combustion engine for the production of energy for car-traction [1,2]. Although, on principle, the PEMFCs can work with different fuels from the simplest hydrocarbons to alcohols, the present technology is limited to the employment of H 2 , but the feeding of the motor-vehicles with hydrogen could cause problems for the fuel tank construction, for the filling stations and, above all, for the safety. Thus, an idea is now spreading to associate the fuel cells with reactors for hydrocarbons and alcohols reforming. The reactor should work at a relatively low temperature and be able to feed the cell with the hydrogen produced during the reaction. Among the fuels to be reformed, methanol is very attractive for its low cost, the high H/C ratio and the absence of coke formation [3]. Recently, an interesting methanol reforming process, named Oxidative Steam Reforming of Methanol (OSRM), has been proposed and is under study in various academic and industrial laboratories [4,5]. OSRM combines the two reactions: CH 3 OH þ H 2 OYCO 2 þ 3H 2 DH- ¼ 49:3kJ mol 1 ð1Þ CH 3 OH þ 1=2O 2 YCO 2 þ 2H 2 DH- ¼ 191:9kJ mol 1 ð2Þ endothermic steam reforming (1) and exothermic partial oxidation (2) and can be carried out in autothermic conditions if the reactor is fed with mixtures of CH 3 OH, H 2 O and O 2 in proper concentration ratio. The reforming process must not 0167-2738/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.ssi.2005.09.051 * Corresponding author. Department of Chemistry, University of Perugia, Via Elce di Sotto, 8, 06127 Perugia, Italy. Tel.: +39 075 585 5565. E-mail address: ucost@unipg.it (U. Costantino). Solid State Ionics 176 (2005) 2917 – 2922 www.elsevier.com/locate/ssi