Jointlypublishedby Elsevi~"ScieaeeB.V., Amsterdam mad Akad,~niai Kiad6, Budapest React.Kinet.Catal.LeU. Vol. 65, No. 2, 227-232 (1998) RKCL3106 CATALYTIC PROPERTIES OF A MIXED CALCIUM-COBALT ORTHOPHOSPHATE, IL DETERMINATION OF THE ACTIVE SITES IN PROPAN-2-OL DEHYDROGENATION A. Legrouri'*, J. Lenzi b and M. Lenzi b "School of Science & Engineering, AI Akhawayn University, P.O. Box 104, Ifrane 53000, Morocco b Centre de G~e Photocbimique, Ecole Nationale Sup6rieure de Chimie, 118 route de Narbonne, 31077 Toulouse-C6dex, France Received February 3, 1998 In revisedform May 18, 1998 Accepted June 30, 1998 Abstract The effect of acidic (phenol) and basic (pyridme) poisons as well as that of water on propan-2-ol dehydrogenation were used to determine the nature of the active sites in the most active catalyst found in the mixed calcium-cobalt orthophosphate system, Ca3-xCox(PO4)2,with x = 0.32. A mechanism for catalyst action is discussed in light of the results obtained. Keywords: Poisoning, phenol, pyridine, dehydrogenation, propan-2-ol, calcium- cobalt orthophosphate INTRODUCTION The surface properties of a catalyst, in particular the nature of the active sites, play an important role in the reaction mechanism. Several studies carried out on catalysts active in dehydrogenation showed that the activity is favored by the presence of basic sites at the surface of the catalyst. On the contrary, dehydration is often explained by the presence of acid sites [1-5]. * E-mail." a. legrouri@alakhawayn, ma 0133-1736D8/US$12.00. 9 A k a d ~ a i Kiad6, Budapest. All rights reserved-