Novel Nano-dispersed Copper Catalysts for Cyclohexanol Dehydrogenation: Synthesis, Physico-chemical Properties, Activity and Stability

Three nano-dispersed catalysts (WS90300, WS70300 and A(90)(300)) were prepared from a copper-carbonate-ammonia complex. The influence of SiO2 (white soot and aerosil), chemical and phase compositions, porous structures, thermal stability and activity of the catalysts were investigated. The catalysts were characterized by FT-IR spectroscopy, low-temperature N-2 adsorption, XRD, EDX, DTA, and SEM. An increase in the temperature of SiO2 treatment in the form of white soot with a copper-ammonia-carbonate solution led to an increase in the proportion of a chemically fixed precursor copper hydroxocarbonate on the surface of the support. The enhanced thermal stability of the catalysts supported on white soot was compared with those prepared on pyrogenic silica. The improvement was attributed to the incorporation of a grafted phase consisting of nano-dispersed copper hydroxocarbonate, as opposed to copper oxide, within the catalyst structure. The best conversion of cyclohexanol was obtained by WS90300 at 250 degrees C (56.5%) with a selectivity range of 99.5 to 99.8%. The order of cyclohexanol conversion was WS90300 > WS70300 > A(90)(300). The catalyst WS90300 was better than the commercially available catalyst H3-11 brand. The catalyst WS90300 gave robust, efficient and reproducible results and can be used to convert cyclohexanol to cyclohexanone at an industrial scale.