Studies Of Selective Hydrogenation Of Phenol Process

Cyclohexanone is a kind of important industrial synthetic materials and chemical intermediates in industry, which is widely used in synthesis of caprolactam, adipic acid,and nylon fiber. It also plays an important role in the region of medicine, pesticide, paint,synthetic materials and so on. Traditional production of cyclohexanone mainly from cyclohexane oxidation, cyclohexene hydration, benzene hydrogenation. These processes exist many drawbacks, including process cumbersome, by-products production, and low utilization rate. In recent years, the researchers try to develop a economy and environmental friendly process of cyclohexanone production process. The selective hydrogenation of phenol to cyclohexanone has obvious advantages, which are simple,convenient operation, mild reaction conditions and less by-product production. This work investigated the Pd and Ni metal catalysts in selective hydrogenation of phenol process to prepare cyclohexanone. The contents of the product cyclohexanone and cyclohexanol are determined by the GC.Firstly, the selective hydrogenation reaction of phenol catalyzed by the commercial5% Pd/C catalyst was studied and the reaction conditions were also optimized. It is obtained the optimum reaction conditions as follows: reaction temperature 110 ℃,reaction time 3 h, hydrogen pressure 2.0 MPa with the phenol conversion is 78.84 %and the cyclohexanone selectivity is 44.78%. It also found that the introduction of lewis acid in the system could improve the conversion of phenol and the selectivity of cyclohexanone.Secondly, the different types of carbon nanotubes supported Ni catalysts were prepared and the effects of different supports and different Ni loading content on the selective phenol hydrogenation were investigated in this work. The results indicate that the Ni/L-2040 catalyst with 30% Ni loading content plays the best catalytic activity. The phenol conversion can reach to 48.25% with the cyclohexanone selectivity of 52.28% under the reaction conditions of reaction temperature 150 ℃,reaction time 3 h, hydrogen pressure 2.0 MPa. By introducing metal Co and the hydrophilic carrier ZrO2 to carbon nanotubes, it can significantly improve theconversion of phenol and the selectivity of cyclohexanone. The phenol conversion is65.85% with the selectivity of cyclohexanone is 74.21%.Finally, the prepared Ni catalysts were characterized by BET, XRD, SEM and the hydrogen chemical adsorption. The results show that these catalysts have mesoporous structure, 30% Ni/L-2040 catalyst has better catalytic effect due to its good structure,and dispersion of Ni particles.