Study On Ruthenium Catalysts For Liquid Phase Hydrogenation Of Benzene To Cyclohexene

Cyclohexene is an important chemical material, which can be oxidized tocyclohexanone and hexane diacid, hydrationed to cyclohexanol. It is widelyused in the production of fine chemicals such as pesticides, pharmaceuticalsand dyes, etc.. Due to the rare content of natural cyclohexene, industrialdemands are satisfied by chemical preparation. Traditional productionmethods of cyclohexene contain dehydrogenation of cyclohexane anddehydrohalogenation of halocyclohexane, etc., but the yield is prevalently lowand the cost is high. The commonly used method, partial hydrogenation ofbenzene, with little environmental pollution, makes full use of the abundantresources of benzene. And it has realized commercial production ofcyclohexene in Japan. But the catalyst is so expensive that it is imperative todevelop a catalyst with independent intellectual property rights.In this work, the effect of different kinds of metal ions on Ru has beenseriously investigated. Then Ru Cd catalyst was prepared, and the effect of Cd content on Ru Cd catalytic performance was analyzed. Finally, the reactionmechanisms of different metal ions on partial hydrogenation of benzene werespeculated with quantum chemistry calculations.First of all, catalysis of Ru catalyst with ZnSO4as additive in a stainlessautoclave was explored. Considering that the poor repeatability of catalyst inthis reactor may be contributed to the erosion, a titanium autoclave withstronger corrosion resistance was chose to study the influence of metal ions(Fe²⁺, Ni²⁺, Cr³⁺and Mn²⁺) on the reactive activity and selectivity tocyclohexene respectively with FeSO₄NiSO₄Cr₂(SO₄)3and MnSO4asadditives, then the temperature and hydrogen pressure effects on the reactionwere investigated.The partial hydrogenation of benzene with ZnSO₄and CdSO₄as additiveswas aslo researched in titanium autoclave. Based on their great difference ofreaction results, Ru Cd catalyst was prepared, and the optimal mole ratio ofCd/Ru was determined to be4%. Meanwhile, the effects of catalystprecipitation method in the preparation process, and catalyst quality of Ru Cdon the reaction were also investigated.The calculation on the binding energies between metal ions (Fe²⁺, Ni²⁺,Cr³⁺, Zn²⁺and Cd²⁺) and benzene as well as cyclohexene were carried out byDFT/B3PW91method. Combined with above experimental results and theICP characterization method, the interaction mechanism of these metal ions onthe partial hydrogenation of benzene was predicted.