Study On The Intensification Mechanism Of Cyclohexene Hydration

Cyclohexanol is an organic chemical with main use for adipic acid and caprolactam production. Synthesis of cyclohexanol by hydration of cyclohexene is an economical, safe and green process. HZSM-5 zeolite is a common catalyst of hydration of cyclohexene. But due to the low mutual solubility between cyclohexene and water and thermodynamic equilibrium, the reaction rate and the conversion of cyclohexene are substantially low. In order to strengthen reaction and mass transfer, cyclohexene hydration catalyzed by HZSM-5 was studied in the presence of ultrasound. It dealt with the effects of different reaction conditions on the conversion of cyclohexene. In addition, a new microtube reactor was developed and exhibited good performance for cyclohexene hydration.The results of study showed that the optimal reaction temperature was 130℃and the cyclohexene conversion was 8.78% under the appropriate ultrasonic power. When the acoustic power was increased from 0 W to 1000 W, the cyclohexene conversion was increased from 7.67% to 8.78%. The optimal volume ratio of cyclohexene to water was 1:1. Otherwise, reaction pressure generally affects sonochemical effect. An increase in ultrasonic power resulted in a decrease in the optimal reaction pressure.Then the effects of different cosolvents on hydration of cyclohexene in the presence of ultrasound were investigated. From the data of the ternary system and LLE phase diagram, it was found that the two-phase region in the ternary system of cyclohexene+water+ isophorone and cyclohexene+water+ ethylene glycol became smaller than that in the ternary system of cyclohexene+water+cyclohexanol. The experimental results also showed that the cyclohexene conversion was increased to 12.7% with cosolvent and ultrasoundFurthermore, the heterogeneous kinetic model was chose to fit the experimental data and the results was satisfactory. The apparent activation energy of cyclohexene hydration with ultrasound obtained is 64.89 kJ/mol; reaction rate constant is 2.44×10-2 mol/s kgcat.At last, the influences of reaction types, feeding ways and flow rate on the yield of cyclohexanol in a new microtube reactor were studied. It was showed that the yield was 5.7% under the conditions of the reaction time 1 h, reaction temperature 403 K.