Preparation And Characterization Of A Novel Catalyst Ru-B/Zn_xZr_yO_z For Hydrogenation Of Benzene To Cyclohexene

Cyclohexene is an important organic chemical raw material, a wide range of uses,especially for nylon-6, nylon-66, polyamide, polyester, and other fine chemicals production.And the process of hydrogenation of benzene to cyclohexene has great market prospects as ashort process, energy efficient and green process route, while the catalyst preparation is thekey to this process.In this paper, the selective hydrogenation of benzene over supported Rucatalysts has been studied.Firstly, nanoscale carbon black was used as a hard template for the preparation ofRu-B/Zn_xZr_yO_zbinary oxide supports with different Zn/Zr molar ratios and a variety ofcharacterizations on the supports were carried out. XRD results showed that the Ru-B/Zn_xZr_yO_zsupport consisted of ZrO2tetragonal crystallites, XRD and TEM results showed that theRu-B/Zn_xZr_yO_zsupport were nanosized. N2physisorption results showed that the physicalproperties of supports with different Zn/Zr ratios have almost the same surface area, totalvolume, and mean diameter.Secondly, Ru-B/Zn1Zr₁₀O₂₁catalysts were prepared by chemical reduction with NaBH4and various characterizations on the catalysts were carried out. XRD and DSC results showedthat the Ru active component is well dispersed on the supports and the Ru-B/Zn1Zr₁₀O₂₁catalyst consisted of an amorphous Ru-B alloy. The catalysts were prepared by differentsupports including Zn1Zr₁O₃, Zn1Zr₅O₁₁, and Zn1Zr₁₀O₂₁with loading content of8%, DSCresluts showed the thermal stability of Ru-B/Ru-B/Zn_xZr_yO_zincreases with increasing Zr content.The catalysts were prepared by Zn1Zr₁₀O₂₁with load content of4%,8%,12%. DSC analysisshowed that the thermal stability of the catalyst decreased with increasing loading content.Finally, the influence of reaction conditions was investigated and the results showed thatreaction temperature140oC, hydrogen pressure of4MPa, ZnSO4addition of19.6g（theamount of water was280mL）, pretreatment for2h were the optimum in the range of research conditions. Under the optimal conditions, the effects of the amount of catalysts, theloading content of ruthenium and the molar ratio of Zn/Zr to catalytic performance wereinvestigated. Experimental resluts showed that The amount of catalyst was4g（the amount ofbenzene was140mL），Ru loading content was8%and Zn/Zr was1/10，the yield ofcyclohexene reached a maximum of43%，and a cyclohexene selectivity of74%and abenzene conversion of58%were achieved at maximum cyclohexene yield.