Partial Hydrogenation Of Benzene To Cyclohexene On Ru@XO₂?X=Ti,Zr And Si? Catalysts

Cyclohexene is an important organic chemical raw material for the production of fine chemicals such as cyclohexanol,adipic acid,polyamide and polyester due to its active C=C double bond.The process of hydrogenation of benzene to cyclohexene has many advantages,such as simple operation of raw materials,low cost of raw materials,simple reaction route and atomic economy.However,benzene is more likely to undergo deep hydrogenation in the hydrogenation reaction to obtain cyclohexane instead of just staying in the intermediate cyclohexene phase in the actual reaction process.In order to improve the selectivity of cyclohexene,the focus of benzene partial hydrogenation is the modification method of the catalyst in the reaction system,in which the hydrophilicity of the catalyst has a crucial influence on the selectivity of cyclohexene.To improve the hydrophilicity of Ru-based catalysts,Ru particles catalysts were prepared by hydrogen reduction Ru3+ method,and Ru@TiO2 catalyst was prepared by coating TiO2 with a hydrophilic material on the surface by sol-gel method.The conditions for the optimal catalytic partial hydrogenation of benzene was explored by the four-factor three-level orthogonal experiment,that is,the reaction temperature was 160?,the H2 partial pressure was 7 MPa,and the ZnSO4 concentration was 0.5 M.The surface morphology and structure of Ru@TiO2 catalysts with different coating amounts were characterized,when the content of coated tetrabutyl titanate(TBOT)was 30 ?L.the highest yield and selectivity of cyclohexene were respectively 52.6 mol%and 61.7%at the conversion of benzene of 85.3%,increased by 37.3%compared to the effect of pure Ru under the same conditions,and the effect of TiO2 coating amount on partial hydrogenation of benzene were discussed.On this basis,the catalyst Ru@XO2(X=Ti,Zr and Si)was prepared by sol-gel method with theoretical molar ratio Ru/TBOT,Ru/TBOZ and Ru/TEOS of 10:1,Under the optimum conditions of TiO2 interaction,the surface morphology,structure,and catalytic performance of benzene partial hydrogenation of different coating layers XO2(X=Ti,Zr,and Si)were investigated.The yield and selectivity of cyclohexene were increased by about 20%?40%compared to Pure Ru particles.The mechanism of action of hydrophilic oxide-coated ruthenium-based catalysts was further discussed from the perspective of competitive adsorption of benzene and cyclohexene in hydrophilic materials.