STUDY OF SOME FACTORS AFFECTING THE RU AND PT DISPERSIONS OVER HIGH-SURFACE-AREA GRAPHITE-SUPPORTED CATALYSTS

In a study of the preparation of carbon-supported Pt and Ru catalysts, three high surface area graphites with similar textural characteristi cs, but differing in surface chemistry, have been used as carriers. Fo ur series of metallic catalysts (two based on Pt and two on Ru) have b een prepared by using different metal precursors and preparation metho ds. The catalysts were characterized by temperature-programmed reducti on, H-2 and CO chemisorption and microcalorimetry of CO chemisorption. The achieved metallic dispersions mainly depend on the reduction-deco mposition treatments and on specific interactions between the metal pa rticles and surface defects at the graphite. Microcalorimetry of CO ad sorption evidences that the presence of oxygen surface groups diminish es the metal-support interaction. (C) 1998 Elsevier Science B.V. All r ights reserved.