J. Phys. IV France 113 (2004) 151
DOI: 10.1051/jp4:20040032

Époxydation du cyclohexène sur des nouveaux catalyseurs à base de silice mésoporeuse organisée

J. Toufaily², T. Hamieh^{2, 3}, M. Soulard⁴, J.-L. Guth⁴, J. Patarin⁴, G. Baydoun², D. Naoufal², M. Kodeih², M.-B. Fadlallah², I. Zeineddine², M. Elrifai², A. Kanj², A. Houteit² and L. Sierra<sup>5

2</sup>  Laboratoire de Chimie Analytique, Matériaux, Surfaces et Interfaces (CHAMSI), Faculté des Sciences, Section 1, Université Libanaise, Hadeth, Beyrouth, Liban
³  Institut de Chimie des Surfaces et Interfaces, ICSI-CNRS, UPR 9096, 15 rue Jean Starcky, BP. 2488, 68057 Mulhouse Cedex, France
⁴  Laboratoire de Matériaux Minéraux, UPRES-A-7016, CNRS, ENSCMu, 3 rue Alfred Werner, 68093 Mulhouse Cedex, France
⁵  Universidad de Antioquia, Medellin, Colombie

Abstract
Heteropoly compounds provide a good basis in acid-base and redox catalysis. In particular, heteropoly acids (HPA) catalyse a wide variety of reactions offering strong options for more efficient and cleaner processes compared to classical inorganic acids. They are more efficient than conventional catalysts, such as silica-alumina, zeolites, etc.. Because of their low surface areas (1-10m ²/g), heteropoly acids are usually supported for catalytic applications. Amorphous silica or all-silica mesoporous molecular sieves are often used as supports for HPA's. These catalysts are usually prepared by the wetness impregnation method. The chief disadvantage of this method is the leaching of the active phase when the catalyst is employed in liquid phase reactions. Our study consisted in the direct incorporation of tungstophosphate species (HPW) into the walls of mesoporous silica. Subsequently, the catalytic activity of a highly-incorporated HPW-MCM-41 material was tested in the epoxidation of cyclohexene using H ₂O ₂ as oxidant. On the basis of the experimental results, the samples show a good cyclohexene conversion rate; five main products were detected, i.e. epoxide, cyclohexanediol, 2-cyclohexene-1-ol or 3-cyclohexene-1-ol, cyclohexanone-2-hydroxy, and 2-cyclohexene-l,4-diol. The epoxide formed during the reaction seems to undergo further hydrolysis into cyclohexanediol. This could be do to the acidic nature of the catalysts.

© EDP Sciences 2004