Synthesis and characterization of Pd-Ni catalysts supported on KIT-6 and their application in cyclohexane oxidation using molecular oxygen

Bimetallic Pd-Ni catalysts were prepared via impregnation method, with effects of Pd/Ni ratio (wt%) on their catalytic performance for the oxidation of cyclohexane with molecular oxygen being investigated. Synthesized catalysts were characterized by a series of techniques including XRD, Nitrogen adsorption–desorption, H2-TPR, XPS, ICP-AES, TEM, SEM, and EDX. Compared to monometallic Pd, the addition of Ni to Pd was found to be effective in enhancing the selective oxidation of cyclohexane. Parameters such as the temperature of the reaction, reaction times, catalyst amount, initial oxygen pressure and different solvents were investigated. Optimum conditions to improve cyclohexane conversion and selectivity towards KA-oil (a mixture of cyclohexanone and cyclohexanol) over 4.0%Pd-4.0%Ni/KIT-6 catalyst included 140 °C, 1.0 MPa O2 and acetonitrile as solvent. Under these reaction conditions, 10.87 % conversion and 95.45 % selectivity for KA-oil were observed after 8 h of reaction. Reusability studies of the selected catalyst revealed an outstanding stability along four reaction cycles.