Effect of ruthenium nickel bimetallic composition on the catalytic performance for benzene hydrogenation to cyclohexane

Abstract

For bimetallic catalysts, the composition of each metal component has a crucial effect on their catalytic performance. In this work, the Ni/Ni(OH)2/C sample is synthesized at room temperature (RT) by a simple hydrazine hydrate reduction method using carbon black as support, and then Ru–Ni/Ni(OH)2/C is prepared via galvanic replacement reaction based on Ni/Ni(OH)2/C. The Ru–Ni/C catalyst can be obtained when Ru–Ni/Ni(OH)2/C is annealed in N2 at 380°C. The different compositions of Ru–Ni bimetallic catalysts are successfully controlled by adjusting the addition amount of aqueous RuCl3 solution during the galvanic replacement process. The RuxNiy/C catalysts (the subscripts represent atomic ratios) are evaluated by the reaction of the hydrogenation of benzene to cyclohexane and the experimental results reveal a strong correlation between the catalytic activity for benzene hydrogenation and Ru/Ni atomic ratios. The Ru0.56Ni0.44/C catalyst exhibits the highest catalytic performance among the RuxNiy/C catalysts in this work. The characterizations of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), high resolution transmission electron microscope (HRTEM) and EDS-elemental mapping for the Ru0.56Ni0.44/C catalyst demonstrate that the nanostructure of Ru-on-Ni/NiO nanoparticles can improve its catalytic properties.