Study On The Selectivity Hydrogebation Of Cyclopentadiene To Cyclopentene

As an important raw material of the organic chemical, cyclopentene is widely used in pharmaceutical industry, organic synthesis and synthetic rubber and other fields. This thesis investigated the preparation of the Ni/γ-Al₂O₃ catalyst, which was used in a fixed-bed reactor for selectivity hydrogenation of cyclopentadiene to cyclopentene,using dicyclopentadiene as the starting material. The suitable conditions of catalyst preparation and reaction were determined, too.At first, the depolymerization manner of the dicyclopentadiene was studied. The results showed that when it was depolymerized in gas phase after purified by distillation, the amounts of dimer in reaction solution did not change much, and also coked and polymerized in the reaction, which affected the continuity and the accuracy of experimental results. Liquid-phase depolymerization manner could effectively reduce the amounts of dimer in reaction solution, and the operation is simple.γ-Al2O3 was selected as a suitable carrier for screening experiments. The preparation conditions of catalyst such as the loading of Ni, impregnation time, calcination temperature, calcination time, addition of second metal were investigated. The appropriate preparation conditions were obtained: prepared by impregnation method, Ni content of 20%(wt), impregnation time of 12h, calcination temperature was 500℃, calcination time was 3 h, under these conditions, the high activity and selectivity were obtained.The reaction conditions were also investigated. The results showed that when using the catalyst prepared under the appropriate conditions in a fixed-bed reactor at atmospheric pressure, reduction temperature was 500℃, reaction temperature was 120℃, H₂/CPD ratio was 1.0, liquid space velocity was 6.0 h^-1, the conversion of cyclopentadiene was 87.7%, the selectivity of cyclopentene was 92.8%.