The partial hydrogenation of benzene to cyclohexene over Ru–Cu catalyst supported on ZnO

The selective hydrogenation of benzene to cyclohexene was studied over Ru–Cu/ZnO catalysts, which were prepared by deposition–precipitation, impregnation and co-precipitation methods. The influence of NaOH on the catalytic performance of catalysts prepared by these methods was discussed in detail. It was demonstrated that NaOH significantly enhanced the selectivity to cyclohexene over Ru–Cu/ZnO catalyst prepared by deposition–precipitation method. The properties of the catalysts were characterized by transmission electron spectroscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption–desorption techniques. The effects of ratio of Ru to Cu, concentration of NaOH and other reaction conditions including reaction temperature, hydrogen pressure, and reaction time on the reaction were studied. Using the preferable catalyst, the yield of cyclohexene reached a maximum of 49.4% with benzene conversion of 72.3% and selectivity to cyclohexene of 68.3%.

Graphical abstractThe selective hydrogenation of benzene to cyclohexene was studied over Ru–Cu/ZnO catalysts, which were prepared by deposition–precipitation, impregnation and co-precipitation methods. Addition of NaOH significantly enhanced the selectivity to cyclohexene over the catalyst prepared by deposition–precipitation method.Figure optionsDownload full-size imageDownload high-quality image (179 K)Download as PowerPoint slideHighlights► Catalysts for selective hydrogenation of benzene to cyclohexene. ► Ru–Cu/ZnO prepared by deposition–precipitation, impregnation and co-precipitation. ► Characterized by TEM, SEM, XRD, XPS and nitrogen adsorption–desorption. ► NaOH significantly improved selectivity when using deposition–precipitation method. ► A maximum yield of cyclohexene 49.4%.