Journal of Power Sources 135 (2004) 177–183 CO selective oxidation on ceria-supported Au catalysts for fuel cell application G. Panzera a , V. Modafferi a , S. Candamano a , A. Donato a , F. Frusteri b , P.L. Antonucci a,∗ a Dipartimento di Meccanica e Materiali, Facoltà di Ingegneria, Università “Mediterranea”, Feo di Vito, 89060 Reggio Calabria, Italy b Istituto CNR-ITAE, Via S. Lucia sopra Contesse 5, 98126 Messina, Italy Received 28 October 2003; received in revised form 17 April 2004; accepted 24 April 2004 Available online 2 July 2004 Abstract Ceria-supported Au catalysts for selective oxidation of CO under simulated fuel processing conditions for polymer electrolyte membrane fuel cell (PEMFC) application were investigated. Fresh and used catalysts were characterized by X-ray diffraction, X-ray fluorescence and transmission electron microscopy (TEM). The influence of catalyst heat treatment, reaction temperature, gas composition and space velocity on CO conversion and CO 2 selectivity has been evaluated. Air calcination at 500 ◦ C resulted in the establishment of adequate interfacial metal oxide properties which are essential to promote the selective CO oxidation. CO conversion close to 100% was obtained at 120 ◦ C, whereas CO 2 selectivities not higher than 40% were obtained in the entire temperature range investigated (80–120 ◦ C). The presence of CO 2 in the inlet stream negatively affected both CO conversion and CO 2 selectivity. Both calcined and uncalcined Au/CeO 2 catalysts resulted to be very stable, as demonstrated by 120h endurance tests. TEM investigation of the used catalysts revealed that a surface Au particles reconstruction occurred during reaction. © 2004 Elsevier B.V. All rights reserved. Keywords: Au catalysts; Ceria support; Selective CO oxidation; PROX; PEMFC 1. Introduction Great R&D efforts are currently being made for polymer electrolyte membrane fuel cells (PEMFC) owing to its ad- vantageous potentialities in automotive applications, such as high efficiency, low emissions and low operating temper- ature [1–3]. On-board hydrogen production should be the most practical way to feed the cell, as no infrastructure for handling and distribution of this fuel is currently available; thus, fuels such as methane, methanol or gasoline must be reformed to obtain a hydrogen-rich gas mixture via a fuel processor. Yet, the as-obtained reformate contains carbon monoxide at concentration levels near 1 vol.%, which irre- versibly poisons the Pt-based anode catalyst of the fuel cell. As a consequence, the CO concentration in the reformate must be reduced to <20 ppm; this could be achieved through its selective oxidation in a preferable oxidation (PROX) pro- cess. In order to avoid the presence of heat exchangers, the most convenient temperature for PROX is the fuel cell op- ∗ Corresponding author. Tel.: +39 0965 875 257; fax: +39 0965 875 201. E-mail address: antonucc@ing.unirc.it (P.L. Antonucci). erating temperature (around 80 ◦ C), although higher values (up to 130 ◦ C) are currently taken into consideration due to the superior CO tolerance of the anode catalyst under this condition. In this temperature range, oxide-supported Au catalysts have demonstrated to be very promising candidates [4–11] for CO selective oxidation; some of these (such as Au/Fe 2 O 3 , Au/MnOx and Au/Co 3 O 4 ) are active at very low temperature, well below the range of interest for fuel cell applications. Several papers on the Au-catalyzed CO oxidation, often contradictory in their conclusions, have been produced in the last few years. Most debated arguments are, in partic- ular, the identification of active species, the role played by the support and, more generally, the mechanism that governs the reaction. In this respect, most of the authors agree with a synergistic mechanism that would occur at the gold–oxide support interface; the nature of this latter plays a well de- fined role in the catalytic process [12–14]. Accordingly, CO oxidation appears to occur with high reaction rates if CO, adsorbed on a gold particle, interacts with oxygen adsorbed on a highly reducible metal oxide support, with subsequent dissociation at the metal–support interface. In this view, the role of the substrate (such as Fe 2 O 3 , TiO 2 , NiO, Co 3 O 4 ) is 0378-7753/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jpowsour.2004.04.006