Application Of Suspension Catalytic Distillation To Benzene Hydrogenation

In this paper, the production methods of Cyclohaxane and Benzene hydrogenation kinetics are overviewed. The suspension catalytic distillation technique was applied to the Benzene hydrogenation process to synthesize Cyclohaxane for the first time in order to solve some industrial problems such as heat exchange in the Caprolactam production process of Baling Petrochem.Corp. The study includes three parts: Benzene hydrogenation kinetics, the design of reaction-distill tower, and the design of technological flow and experiments.The results of Benzene hydrogenation kinetics show that the activation energy is 55.63 kJ/mol, the reaction order of Benzene is 0.5 with the HC-402-2 homogeneous catalyst in the Benzene hydrogenation process. The concentration of catalyst has great influence on reaction rate, the increase in catalyst concentration greatly improve the reaction rate. The reaction rate equation can be expressed as-rA = (0.0016/T1.5)×exp(-6691.3/T)×PH21.5×CNi3×CA0.5 if the stir rate is big enough, i.e., the gas phase and liquid phase can mix completely.Under the technology parameters of tower pressure is 1700 kPa; tower temperature is over 180℃; the highest tower temperature is less that 215℃and the hydrogen flow quantity is 75SLM, the reaction-distill tower can work but easily leak or overflow. A further investigation shows the increase of tower plate distance is the effective way for increasing the operation elasticity. The design of Benzene hydrogenation reaction distill tower provides theoretical basis for the devices enlarging and the establishing of theory model. From the running results of the experimental devices, it is found that the theoretical design results approximately fit with the experimental ones. At the temperature range of 140-200℃, reaction pressure 0.8 MPa-2.0 MPa, the transformation ratio of Benzene is 99.99%; the highest of utilance of hydrogen reaches 90%.Three technological flows are designed for Benzene hydrogenation catalyzing process. Flow 1 is suitable for the capacity enlarging of Benzene hydrogenation equipments of Baling Petrochem. Corp., and it can be also used alone. Flow 2 is suitable for the pre-reactor of Benzene hydrogenation. Row 3 can be used to the independent Benzene hydrogenation reactor.The following conclusions can be drawn from the technological flow design and experimental study: (1) the tower pore plate kinetic energy factor is higher than 4, the coefficient of pore flow is about 0.4-0.5. (2) the reaction temperature should be controlled under 200℃since the stability of HC-402-2 homogeneous catalyst is influenced by temperature, above that temperature, the structure of nickel - organic catalyst can be unstable and produce some nickel precipitation. The precipitation not only decreases the catalyst activity but also blocks up the sieve pore, thereby has great influence on the distill tower function. (3) Benzene hydrogenation catalyze reaction-distill technique is feasible, and the temperature and pressure are easily controlled. (4) The reaction tower is one of the important part in the Benzene hydrogenation system, from a independent hydrogenation experiment it can be seen that catalyst concentration and hydrogen flow quantity are the main factors influencing the tower reaction ability and transformation ratio.