Catalysis Letters 14 (1992) 37-43 37 Modification of copper by redox reaction: location of Ru on Cu-Ru bimetallic catalysts J. Barbier, J.C. Menezo, C. Montassier, J. Naja LACCO, Unitd de Recherche associde au CNRS, DO 350, Universitd de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers Cedex, France G. Del Angel Departamento de Quimica, Universitad Autonoma Metropolitana-Iztapalapa, Apdo-Posta155-534, 09340 DF Mexico and J.M. Dominguez Instituto Mexicano del Petroleo, I.A. Apdo Pastal 14-805, Eje Central L. Cardenas 152, 07730 DF Mexico Received 30 January 1992; accepted 2 April 1992 Raney copper catalysts were modified by addition of ruthenium by means of an oxido-re- duction reaction between copper surface and ruthenium chloride in aqueous solution. Energy dispersive spectroscopy fitted to a STEM unit allowed to conclude that the active sites for the selective conversion of glucitol into 1,4-3,6-dianhydroglucitol are composed of ruthenium and chlorine located on low coordinated copper atoms. Keywords: Copper-ruthenium catalysts; EDS/STEM bimetals characterization; Ru/Cu decoration catalysts 1. Introduction The catalytic properties in conversion of polyols on Raney copper and supported ruthenium catalysts have been described in recent papers [1,2]. On Raney copper [1] C-C and C-O bonds cleavages are slow and proceed by steps of dehydrogenation of alcoholic functions followed by nucleophilic attacks of carbonylated intermediates so formed. On the contrary, ruthenium catalysts [2] are very active for direct C-C and C-O bonds hydrogenolysis leading ultimately, in the same conditions, to C a molecules (methane). 9 J.C. Baltzer A.G. Scientific Publishing Company