Study On Hydrogenation Of Phenol To Cyclohexanone Based On Pd/C Catalyst

Cyclohexanone,a widely used organic chemical raw material,plays a very important role in industrial production.Hydrogenation of phenol to cyclohexanone has the advantages of mild reaction conditions,few by-products,and environmental friendliness.The suitable reaction conditions,intrinsic kinetics and heat transfer characteristics of Pd/C catalyst for phenol gas-phase hydrogenation were studied over a new Pd/C catalyst developed by a domestic company.The results obtained can be applied for pilotplant experiment and the design of phenol hydrogenation reactor.The effects of solvents,such as dichloromethane,cyclohexane,ethanol,and benzene,were compared on phenol hydrogenation.At the reaction temperature 160?-250?,the reaction pressure 0.1?MPa?2.0MPa,the weight hourly space velocity of phenol 0.2h-1?1.0h-1,the ratio of the amount substance of hydrogen to phenol 2?12,the effect of experimental conditions on the hydrogenation of phenol was explored.The more suitable phenol hydrogenation reaction conditions are:benzene as the solvent,reaction temperature 175?-205?,reaction pressure 0.1MPa,the weight hourly space velocity of phenol 0.2h-1?0.4h-1,and n(H2)/n(phenol)4.Eliminating the influence of internal and external diffusion,25 sets of intrinsic kinetic experimental data were measured.Based on the Langmuir-Hinshellwood-Hougen-Watson theory,an intrinsic kinetic model was established.And 25 sets of kinetic experimental data were substituted into the model to obtain the parameter estimates of the model.Statistical tests and residual analysis showed that the intrinsic kinetic model is reliable.In the state of gas flow but no chemical reaction,the heat transfer characteristics of Pd/C catalyst in a fixed-bed reactor were experimentally studied.The effect of experimental conditions on the temperature distribution in the fixed-bed was investigated.A two-dimensional pseudo-homogeneous heat transfer model of Pd/C catalyst in a fixed-bed reactor was established.Using the orthogonal configuration method to solve the model,radial effective thermal conductivity and wall heating coefficient were obtained.Radial effective thermal conductivity and wall heating coefficient were related by particle Reynolds number.