Coupling of Cyclohexanol Dehydrogenation-nitrobenzene Hydrogenation Over MgO-Al2O3 Hydrotalcite Supported Cu Catalysts: Effect of Cu Loading

A series of Cu/ (MgO-Al2O3) hydrotalcite catalysts have been prepared by impregnation technique with a Cu loading ranging between 5 to 25wt%. The prepared catalysts have been characterized by BET technique, X-Ray diffraction, temperature programmed reduction (TPR) and N2O pulse chemisorption techniques. Cyclohexanol dehydrogenation and nitrobenzene hydrogenation (individual reactions) and coupling of these two reactions have been performed over these catalysts in vapor phase at atmospheric pressure and at 548K. XRD results reveal the intactness of hydrotalcite structure in reduced and used catalysts with Cu loadings below 15wt%. The beauty of the coupling reaction is to yield cyclohexanone and aniline from cyclohexanol and nitrobenzene respectively with stoichiometric quantity of H2 usage for nitrobenzene hydrogenation. The catalyst with 10wt% Cu loading showed higher activity in the coupling reaction which could be attributed to the better Cu dispersion, smaller Cu particle size and relatively more number of Cu active species presented on the surface of the catalyst.