Catalysis Letters, Vol.147, No.2, 525-538, 2017
Ternary (Cu, Ni and Co) Nanocatalysts for Hydrogenation of Octanal to Octanol: An Insight into the Cooperative Effect
Ternary metal oxides (Cu-Ni-Co) with different wt% loadings were supported on alumina by using an ultrasonic cavitation-impregnation method. A comparative silica catalyst was also prepared. Powder X-ray diffraction (XRD) showed the presence of the metal oxides on the surface of the supports and from in situ XRD results, the formation of metallic phases under a reducing atmosphere were observed. Temperature-programmed desorption (TPD) revealed the presence of Lewis and Bronsted acidic sites in the catalysts. The metals supported on alumina showed a better dispersion compared to that on the silica support. All the catalysts were tested for the hydrogenation of octanal in a mixture of 10% octanal in octanol in a continuous flow fixed bed reactor by varying the pressure, temperature and hydrogen molar ratios. Under the hydrogenation conditions, the trimetallic catalysts (with Cu, Ni and Co) showed best catalytic performance for octanal hydrogenation when compared to bimetallic catalysts. The conversion of octanal and the selectivity towards octanol increased in proportion to an increase in the total metallic content and metal dispersion. The alumina based catalysts showed better activity compared to the silica catalyst due to higher metal dispersion. The silica supported catalyst showed a high selectivity towards C24 acetal due to its higher acidity and the product distribution over all the catalysts is in agreement with the distribution of acidic sites. [GRAPHICS] .