Jointly published by Akadémiai Kiadó, Budapest and Springer, Dordrecht
React.Kinet.Catal.Lett. Vol. 87, No. 2, 269-279 (2006)
RKCL4905 CATALYTIC WET AIR OXIDATION OF OLEIC ACID ON CERIASUPPORTED PLATINUM CATALYST. EFFECT OF pH Benoît Levasseur, Benoist Renard, Jacques Barbier, Jr.* and Daniel Duprez Laboratoire de Catalyse en Chimie Organique, LACCO UMR 6503, CNRS and Université de Poitiers, 40 avenue du Recteur Pineau, 82022 Poitiers Cedex France Received July 6, 2005 Accepted July 20, 2005
Abstract Catalytic wet air oxidation (CWAO) of oleic acid was carried out in a batch reactor on platinum supported ceria catalyst (Pt/CeO2). Oleic acid is a water insoluble linear unsaturated fatty acid of 18 carbon atoms. To increase the homogeneity of the solution by saponification, the influence of NaOH additions in oleic acid CWAO mechanism and catalyst performances have been investigated. The oxidation of such molecule occurs by two types of mechanisms: successive carboxy-decarboxylation which leads essentially to CO2 and/or C-C bonds splitting in the alkyl chain inducing a high formation of acetic acid. With or without NaOH, the 5%Pt/CeO2 catalyst is active in the conversion of oleic acid and selective to carbon dioxide. In alkaline medium, oleic acid is initially saponified which increases the solubility of the reactant before it to be oxidized. Finally the oxidation is slightly delayed by the presence of NaOH. The catalyst characterizations show no significant difference before and after reaction. Keywords: Catalytic wet air oxidation (CWAO), oleic acid, Pt/CeO2 catalysts, saponification, catalytic water treatment
INTRODUCTION Since several years, water pollution has become a major environmental problem requiring more and more complex solutions. Many conventional processes already exist and are able to eliminate the majority of the pollutants in water [1]. Among these techniques, wet air oxidation (WAO) can be applied for __________________________ Dedicated to Professor Zoltán Paál on the occasion of his 70th birthday. * Corresponding author. Tel.: +33 549 454 831; fax : +33 549 453 499 E-mail:
[email protected] 0133-1736/2006/US$ 20.00. © Akadémiai Kiadó, Budapest. All rights reserved.
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the treatment of effluents with medium chemical oxygen demand (10g(O2).L-1< COD
