Study On Catalytic Oxidation Of 2,3,6-trimethylphenol In A Rotor-stator Reactor

Vitamin E as an important nutrient in human body is widely needed by people.2,3,5-trimethyl-1,4-benzoquinone(TMQ)is an imperative intermediate in the synthesis of vitamin E,and catalytic oxidation of 2,3,6-trimethylphenol(TMP)to TMQ is the main method for industrial production of TMQ because of easy availability of raw materials,simple process and high yield.However,this method has the shortcomings of long reaction time as well as low oxygen utilization.This study thus applied high gravity technology to the catalytic oxidation of TMP to produce TMQ by a gas-liquid-liquid three-phase reaction system with CuCl2 as catalyst dissolved in water phase,2,3,6-trimethylphenol dissolved in oil phase and oxygen as gas phase,in order to realize the intensification of this reaction by the high gravity technology to facilitate liquid-liquid mixture and gas-liquid mass transfer.This thesis selected rotor-stator reactor(RSR)as the high gravity equipment,and the effect of operating conditions on TMP conversion and TMQ yield in three processes was investigated,and suitable reaction conditions were determined.The conclusions are shown as follows:(1)The research results of STR processThe catalytic process of TMP was participated by both transition metal ions and C1-in the catalyst.Catalytic oxidation of TMP consisted of activation process and oxidation process,and the former was faster than the latter.With the increase of rotation speed,the conversion and yield increased before leveling off.As gas flow rate rose,conversion remained stable while yield increased first and then leveled off.The optimum rotation speed and gas flow rate were 1000 rpm and 20 L/h respectively.The rise of the volume fraction of water phase in liquid phase and reaction temperature boosted conversion and yield significantly.(2)The research results of RSR processWith the increase of rotation speed of RSR,both conversion and yield increased first and tend to be stable then.When gas flow rate rose,conversion kept stable first and then decreased,and yield increased first before it started to drop.The effect of countercurrent contact was superior to that of co-current contact.Conversion and yield went up and then remained stable as the liquid flow rate increased.The rise of volume fraction of water phase in liquid phase and reaction temperature enhanced conversion and yield.Finally,the optimum process conditions for rotation speed,gas flow rate,and liquid flow rate were 600 rpm,60 L/h and 40 L/h respectively.(3)The research results of STR+RSR tandem processConversion and yield increased first and decreased then with an increasing rotation speed,and 600 rpm was determined as the optimum rotation speed.The effect of gas flow rate,liquid flow rate,volume fraction of water phase and reaction temperature on conversion and yield in this process was the same as that in the RSR process.The optimum gas and liquid flow rates were 80 L/h and 30 L/h respectively.(4)Comparison of the three processesCompared with the STR process,the RSR process showed a higher conversion but a similar yield under the optimum conditions.Compared with the RSR and STR processes,both conversion and yield in the STR+RSR tandem process increased significantly,indicating that the STR+RSR tandem process is an effective route to produce TMQ.