Study On Preparation Of Ru-Zn Catalyst And Hydrogenation Of Benzene To Cyclohexene

With a wide range of uses, cyclohexene is an important intermediate in organic synthesis. Selective hydrogenation of benzene is currently the best method for producing cyclohexene. According to the method, the key to it is the preparation of catalyst. This paper mainly studies preparation and characterization of the catalyst which is used for selective hydrogenation of benzene to cyclohexene. The effects of additives in preparation process, the introduction of second assistants and the catalyst life are studied next.The preparation of the catalyst precursor is using coprecipitation method. The catalyst preparation will be finished by going on the parts of after processing such as crystallization, reduction and lixiviation. To study the effects of different additives in the preparation of catalyst, some inorganic compounds, organic compounds and ionic liquids are added to the reaction medium of coprecipitation. Among them, the best inorganic additive is A-D. The concentration of D should be 3.0mol-L-1. The pH of solution is adjusted by the addition of another inorganic compound A. The highest activity of catalyst will be acquired when the pH of solution is adjusted to 9.5. The yield of cyclohexene can hit 50.4%. The best organic additive is ethanol. The yield of cyclohexene is 44.5% when the volume ratio of ethanol to H2O is 1:1. The effects of four kinds of ionic liquids are similar to ethanol. And the yield of cyclohexene can hit 46.7% when C6H11N2BF4 are added to the reaction medium in the preparation of Ru-Zn catalyst. Additive can promote the coprecipitation of ruthenium and zinc. Therefore, it can improve catalyst activity and repeatability of preparation.Based on these substances, the effect of second assistant M in the preparation of catalyst is studied. According to the Ru/Zn feed ratio of 1:1, the Ru/(Zn+M) feed ratio is selected as 1:1. The highest activity of Ru-Zn-Rh catalyst will be acquired when the Zn/Rh feed ratio is 1:0.05. And the yield of Cyclohexene is 57.4%.Life test is carried out using the Ru-Zn catalyst. It shows good stability in this experimental apparatus and conditions. The yield of cyclohexene of 50.4% reduces to 45.5% from the first experiment to the eighth. The main cause of the reduction is the loss of catalyst components, which is caused by experimental operations.