Stability and selectivity of bimetallic Cu-Co/SiO2 catalysts for cyclohexanol dehydrogenation

Bimetallic Cu-Co/SiO2 catalysts with different metal loading (5:5, 15:15, 35:35 - Cu:Co) were prepared by deposition-precipitation method and evaluated by using the cyclohexanol dehydrogenation. XRD results show that only the 15%Co/SiO2 oxide precursor exhibits mainly a phase containing Cu and Co with spinel-like structure, while other bimetallic precursors present CuO and Co3O4 as distinct phases. The Rietveld method was used to quantify the different phases on the precursors and to determinate how much Cu there was in the spinel form and as CuO. After reduction and passivation, the 15%Cu-15%Co/SiO2 catalyst showed a Cu-Co ahoy formation and a different H-2 chemisorption capacity. The H-2 uptake was 2.5 greater than 35%Cu-35%Co/SiO2 catalyst and the same order of magnitude for the monometallic 35%Co/SiO2. Catalytic results showed that the 15%Cu-15%Co/SiO2 catalyst presented the highest stability and selectivity to cyclohexanone, with the lowest phenol production. (C) 1999 Elsevier Science B.V. All rights reserved.