The Preparation and Characterization of Well-Dispersed Copper/Carbon Systems for Use as Selective Hydrogenation and Nitrous-Oxide Decomposition Catalyst

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ABSTRACT CTS-9415335 M. Albert Vannice Copper crystallites dispersed on three allotropic forms of carbon are prepared, characterized, and examined as catalysts for selective hydrogenation of conjugated systems and decomposition of nitrous oxide. Both very small and large copper particles are placed on high-surface-area graphitized carbon fibers, diamond films, and activated amorphous carbon. The influence of pretreatment on the size, morphology, and chemical state of the copper particles is investigated. Characterization is accomplished using controlled-atmosphere electron microscopy (CAEM), high-resolution transmission electron microscopy, chemisorption, X-ray diffraction, diffuse-reflectance Fourier-transform infrared spectroscopy (DRIFTS), electron spin resonance (ESR), and copper-63 solid-state nuclear magnetic resonance. Microwave techniques to measure the electron ability and conductivity of carbon are used to guage the effect of pretreatment on the electrical properties of the three forms of carbon and the influence of small adsorbed molecules. Test reactions include hydrogenation of furfural to furfurol, hydrogenation of crontonaldehyde to crotyl alcohol, and decomposition of nitrous oxide. A commercial copper-chromite catalyst is studied for comparison. The effects of copper crystallite size and type of carbon support on specific activity are determined. These new copper/carbon catalyst have three potentially significant industrial applications: replacement of commercial copper-chromite catalyst because spent chromite catalysts are a hazardous waste and hen e a disposal problem; development of new copper catalysts to reduce unwanted byproducts from selective hydrogenations; and decomposition of nitrous oxide, a greenhouse gas, produced as a byproduct in certain industrial processes such as production of adipic acid, a precursor of nylon. This award is part of the Environmentally Benign Chemical Synthesis and Processing Initiative. ***