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Design and preparation of efficient and greener catalytic systems for partial hydrogenation of benzene to cyclohexene is an interesting topic in green chemistry. In this work, Ru and Ru–Zn catalysts supported on hydroxyapatite (HAP), which is nontoxic and abundant in nature, were prepared via the simple ion-exchange method. The catalysts were characterized by powder X-ray diffraction (XRD), transmission electron spectroscopy (TEM), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption–desorption methods. The influences of Ru/Zn molar ratio, reaction temperature, pressure, reaction time, and amount of modifier NaOH on the partial hydrogenation of benzene were studied in detail. It was demonstrated that metallic nanoparticles of less than 2 nm were dispersed uniformly on the surface of the HAP, and the bimetallic Ru–Zn/HAP catalysts showed high activity and selectivity. The yield of cyclohexene could reach 33% over Ru–Zn/HAP at the optimized conditions, and the catalyst could be reused at least four times without obvious loss of the activity and selectivity. [ABSTRACT FROM AUTHOR]

A simple and efficient route for the immobilization of noble metal nanoparticles onto metal–organic framework (MOF) has been designed in this work. The Ru/MOF nanocomposites were prepared using RuCl3·3H2O as a precursor in supercritical CO2-methanol solution at 200 °C. The as-synthesized Ru/MOF composite presented a high catalytic performance for the hydrogenation of cyclohexene and benzene. There was almost no activity loss after the catalyst was reused five times. The intermolecular interactions between the MOF and Ru nanoparticles were investigated by X-ray photoelectron spectra and FT-IR spectra. It was shown that the carboxylate groups of MOF were coordinated to Ru. The formation mechanism of the Ru/MOF nanocomposites in supercritical CO2-methanol solution through an inorganic reaction route was discussed. This method can be easily applied to the synthesis of other MOF-supported metal nanoparticles. [ABSTRACT FROM AUTHOR]

The Ru/ZnO–ZrOx(OH)y catalyst is very efficient for the selective hydrogenation of benzene to cyclohexene, and the yield of cyclohexene can reach 56% without using any additive. This work provides a highly efficient, cheap and clean method to produce cyclohexene. [ABSTRACT FROM AUTHOR]

Abstract: A ruthenium catalyst supported on the cheap bentonite with high activity has been prepared by impregnation-hydrothermal method and characterized by TEM, XRD, and XPS. The catalytic performance for selective hydrogenation of benzene to cyclohexene was investigated. The effect of additives NaOH and ZnSO4 on the catalytic performances was studied. It was demonstrated that both NaOH and ZnSO4 could significantly enhance the selectivity to cyclohexene over Ru/bentonite catalyst. The influences of reaction temperature, pressure, amounts of catalyst and additives, and reaction time on the selective hydrogenation of benzene were studied in detail. [Copyright &y& Elsevier]