The drastic effect of platinum on carbon-supported ruthenium-tin catalysts used for hydrogenation reactions of carboxylic acids

The incorporation of platinum on bimetallic ruthenium-tin catalysts supported on active carbon has profound effects on the catalytic behavior. The reaction rate was accelerated nearly three times compared with that of the bimetallic system for the hydrogenation of 1,4-cyclohexanedicarboxylic acid (CHDA). Moreover, it turned out that Pt can completely prevent Sn, one component of the catalyst, from dissolving into the reaction mixture, whereas a considerable amount of dissolved Sn was detected in a binary Ru-Sn catalyst during hydrogenation. We verified the durability of our catalyst by carrying out a catalyst recycling test over seven cycles. The characterization of the catalyst has been evaluated by the temperature programmed reduction, X-ray photoelectron spectroscopy and X-ray diffraction as well as electron microscopy. A significant difference in the catalytic properties of the resulting Ru-Pt-Sn catalyst from a binary one exists in the valence state of the tin species, which is present mostly as Sn(0). It is postulated that the high performance of this novel catalyst in terms of activity and durability are related to this point. (C) 2002 Elsevier Science B.V. All rights reserved.