Investigation of catalytic oxidation of carbon monoxide over a Cu±Cr-oxide catalyst made by self-propagating high-temperature synthesis Galina Xanthopoulou 1 , George Vekinis * Institute of Materials Science, National Centre for Scienti®c Research ``Demokritos'', Aghia Paraskevi Attikis, 15310, Greece Received 25 January 1998; received in revised form 15 March 1998; accepted 21 May 1998 Abstract The self-propagating high-temperature synthesis (SHS) method has been used to produce a highly active Cu±Cr±O mixed spinel catalyst for the oxidation of CO. SHS is characterised by processing times of the order of minutes, low preheating temperatures and high reaction temperatures produced as a result of carefully designed exothermic reactions. A range of active catalysts have been developed for various applications including oxidation of CO. The Cu±Cr±O catalyst presented here is known to be resistant to fuel impurity poisoning and high temperatures and, used as carrier for 0.05% Pd, achieved 50% conversion (light-off) at temperatures about 508C lower than conventional 0.5% Pd/Al 2 O 3 catalysts. CO catalytic conversion of 90% is reached at temperatures of about 3008C and 100% at 4008C. In pellet-form without any noble metals, it reaches CO conversion of 100% at 4008C, even though its speci®c area was only about 1 m 2 /g as compared to about 90% for traditional Pd/Al 2 O 3 catalysts with much higher speci®c area. # 1998 Elsevier Science B.V. All rights reserved. Keywords: Self-propagating high-temperature synthesis; SHS; Carbon monoxide; Catalytic oxidation; Spinel catalyst 1. Introduction Traditional vehicle exhaust catalysts are usually made of a small percentage of noble metals (usually 0.05±0.1%) such as Pt or Pd dispersed on a high surface area carrier [1±5] made of alumina supported on cordierite with a honeycomb geometry. The com- plicated method of production in conjunction with the high cost and rarity of the raw materials used makes these systems expensive. Such catalyst systems are chemically sensitive and may degrade quickly in the presence of fuel impurities. Moreover, they do not display any signi®cant catalytic activity at tempera- tures lower than 150±2008C which results in ``light- off'' times of the order of minutes for cold starts [1]. These factors have encouraged the development of cheaper and more effective materials based on metal oxides [1,6±18]. Transition metal oxide systems are different from noble-metal catalysts in relation to their adsorption behaviour of reaction products. Their catalytic oxida- tion of CO is performed by a series of reaction steps, while the adsorption of CO proceeds quickly and is Applied Catalysis B: Environmental 19 (1998) 37±44 *Corresponding author. Tel: +30-1-6503322; fax: +30-1- 6533872; e-mail: gvekinis@ims.ariadne-t.gr 1 ex Galina Gladoun, Combustion Problems Institute, Almaty, Kazakhstan. 0926-3373/98/$ ± see front matter # 1998 Elsevier Science B.V. All rights reserved. PII: S0926-3373(98)00056-3