Applied Catalysis A: General 252 (2003) 385–397 FTIR study of low-temperature water-gas shift reaction on gold/ceria catalyst Tatyana Tabakova a,∗ , Flora Boccuzzi b , Maela Manzoli b , Donka Andreeva a a Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., bl. 11, 1113 Sofia, Bulgaria b Department of Chemistry IFM, University of Torino, via Pietro Giuria 7, 10125 Torino, Italy Received 17 December 2002; received in revised form 29 May 2003; accepted 2 June 2003 Abstract Chemisorption and reactivity of the molecules involved in the water-gas shift (WGS) reaction on gold/ceria catalyst have been studied at 90 and 300 K by FTIR spectroscopy. Forward and reverse WGS reaction at 300 K and up to 573 K have been investigated, too. The FTIR results show that gold causes a strong modification of the surface properties of the support. The nanosized metallic gold particles in close contact with defective ceria play an essential role for the genesis of high catalytic activity in WGS reaction at low temperature and appear to be of crucial importance in explaining the remarkably high stability of this catalytic system. An electronic interaction between small gold metallic nanoparticles and ceria has been evidenced. © 2003 Elsevier B.V. All rights reserved. Keywords: Gold/ceria catalyst; FTIR; WGS reaction mechanism 1. Introduction The renewed interest recently shown in the water-gas shift (WGS) reaction is due to the rapid de- velopment of fuel-cell power systems and to the need for pure hydrogen production [1–3]. Moreover, WGS reaction is one of the key steps involved in the auto- mobile exhaust processes, converting CO and water to hydrogen and CO 2 and including the produced hy- drogen as a very effective reductant for NO x removal. A dramatic growth of interest in the catalytic power of gold has been occurred over the past 15 years [4]. First of all, Haruta et al. have established that Au ex- hibits an extraordinary high activity in CO oxidation at low temperature when dispersed as ultrafine particles [5]. Differently from the other noble metals catalysts, ∗ Correspodning author. Tel.: +359-2-9792528. E-mail address: tabakova@ic.bas.bg (T. Tabakova). the preparation method is crucial for the genesis of catalytic activity of gold catalysts. Only the methods which provide a strong interaction between the metal particles and the support can produce gold catalyst with high performance [6]. Moreover, also the choice of the support plays a very important role in the devel- opment of novel gold catalysts. Previous studies indi- cated that gold particles finely dispersed (2–5 nm) on Fe 2 O 3 , TiO 2 , ZrO 2 exhibit high catalytic activity in the low-temperature WGS reaction [7–10]. More recently, several groups have reported the low-temperature cat- alytic activity of Au/CeO 2 catalysts [11–14]. CeO 2 is extensively employed as a component in the automo- tive, three-way emission-control catalysts, mainly due to its capacity to undergo a relatively rapid change in oxidation state upon changes in the redox potential of the exhaust gases. CeO 2 is used to maintain the no- ble metals dispersion and to promote WGS reaction, too. 0926-860X/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0926-860X(03)00493-9