Study On Catalyst Of Benzene Hydrogenation To Cyclohexane

As one of the most important industrial raw materials and organic solvents, cyclohexane can be gained through the way of distilling petroleum fraction or benzene hydrogenation. However, with the development of modern industry, the need of cyclohexane is on the increase, and its production approach has also changed. Due to the fact that the cyclohexane produced by distillation cannot meet the demand both in quantity and in quality, using the way of benzene hydrogenation to produce cyclohexane has become the main approach. Nowadays, the catalyst of benzene hydrogenation used in industry is mainly the nickel-based one, but it’s easy to overheat in a certain part in the process of reaction, causing the accumulation of carbon and the deactivation of catalyst. As a result, the lifespan of the catalyst will be shortened and the cost of the production will be increased. Then we can naturally draw a conclusion that it’s especially vital to develop a kind of catalyst which is of high reactivity, well dispersion of active component, and long lifespan. This thesis studies the benzene hydrogenation property of the supported Ni/γ-Al2O3 catalyst which is prepared by equivalent-volume impregnation, and inspects its preparation condition, reaction technological condition and its influence on the activity of benzene hydrogenation catalyst by adding the promoter of Cu, Fe, Co, Ce, La. Subsequently, I further investigate the effect on the property of Ni-La/γ-Al2O3 catalyst through microwave assisted impregnation and finally confirm the preparation condition of Ni-La/γ-Al2O3 and the reaction technological condition of benzene hydrogenation.Initially, using the method of equivalent-volume impregnation to prepare the supported Ni/γ-Al2O3 catalyst, inspect γ-Al2O3 carriers made from different methods in high pressure micro-reactor, the capacity of active component Ni, and the influence of calcination temperature on benzene hydrogenation catalyst. The experimental results suggest that the surface area, pore volume and pore diameter of the carrier prepared by calcinating the pseudo-boehmite are all bigger than those of the commercially available γ-Al2O3 globule carrier and the γ-Al2O3 carrier prepared by sol-gel method. Moreover, it’s more suitable for the benzene hydrogenation reaction. The catalyst’s activity has also been promoted due to the increase of Ni content. Containing 10% Ni and the 400℃ of calcination temperature are the suitable preparation conditions for the γ-Al2O3 catalyst. The reaction temperature of 160 ℃, the reaction pressure of 0.8MPa, the airspeed of 5h-1 and the ratio of hydrogen and benzene for 4:1, are the optimal process conditions for the preparing reaction of hydrogenation of benzene to cyclohexane. In this condition, the conversion rate of benzene is 97.5%.Prepare the supported Ni-A/γ-Al2O3 catalyst(A stands for Cu, Fe, Co, Ce, La) by the approach of equivalent-volume impregnation and characterize the catalyst by XRD, H2-TPR, SEM. And then inspect the influence of different additives with varying contents on the performance of benzene hydrogenation catalyst. The experimental results suggest that different additives have different effects on the structure and activity of catalyst. In addition, the addictive La shows its higher activity than any other addictives with varying contents and the Ni-La/γ-Al2O3 catalyst expresses its highest activity in the condition of Ni : La=4:1(molar ratio). The optimal process conditions of benzene hydrogenation reaction for Ni-La/γ-Al2O3 catalyst are the reaction temperature of 160 ℃, the reaction pressure of 0.8MPa, the airspeed of 6h-1, and the ratio of hydrogenation and benzene for 4:1. In this condition, the conversion rate of benzene is 100%.Prepare the supported Ni-La/γ-Al2O3 catalyst by the microwave immersion method and characterize the catalyst by XRD、TPR、SEM、BET. And then inspect the influence of the molar ratio of Nickel and Lanthanum, the calcination temperature, and the microwave time and power on the performance of benzene hydrogenation catalyst. The experimental results suggest that microwave processing can contribute to decreasing the grain size of Nickel component and increasing the dispersion of active component. The optimal preparation conditions for Ni-La/γ-Al2O3(MW)catalyst are Ni : La=4:1, the calcination temperature of 400℃, the microwave time of 30 min, and the microwave power of 600 W. And the optimal process conditions for benzene hydrogenation to cyclohexane are the reaction temperature of 160℃, the reaction pressure of 0.8MPa, the airspeed of 6h-1, and the ratio of hydrogenation and benzene for 3:1. In this condition, the conversion rate of benzene is also 100%.