Process Development Of Sec-butylacetate

There exist disadvantages of high cost, the waste of the heat of reaction and therefined difficult of crude product in the traditional sec-butyl acetate production process.For this, Reactive Distillation （RD） was introduced in order to improve the defects.Reaction and distillation were integrated in the RD column. Distillation was improvedby reaction so that the conversion rate of acetic acid was effectively improved, thus theload and energy consumption of the following refined section were reduced. Becausethe reaction is exothermic, we can make reaction zone as reboiler of distillationseparation of liquefied petroleum gas （LPG） and acetic acid to achieve full utilizationof reaction heat. The three sections contained reaction, LPG refining and refinedproduct were reduced to two sections only contained reaction and refined product.Therefore, the equipment investment and energy consumption were significantlyreduced. The continuous production of sec-butyl acetate using RD technology wasstudied systematically through the method of combining experiment and Aspen Plussimulation together.The reaction between acetic acid and LPG was studied by small scale experiment.The experiment results showed that the optimal reaction temperature was110¹20℃and the reaction kinetic parameters were: k=8.5×10³mol8.43·L^-7.43·min^-1, Ea=7.289×10⁵J/mol, A=1.07×10¹².RD pilot was constructed based on the small scale experiment to carry outcontinuous production. By controlling proper reflux ratio, a continuous high purityproduct of LPG was recovered from the top of the column while the crude product wascollected from the bottom. The process operating parameters were researched toprovide data for industrial design. The temperature of the top of column was54.3℃.The temperature of the bottom of rectification section was83℃. The temperature ofthe bottom of column was124.4℃. The LPG of top of column was100%. The aceticacid of bottom of column was35.78%, sec-butyl acetate44.90%, LPG19.32%.The process was simulated by ASPEN PLUS and the good agreement betweensimulation result and the pilot experiment indicated that the software can be used for sec-butyl acetate of RD process simulation. Preliminary design of the continuous RDprocess for sec-butyl acetate production was carried out, the process equipmentparameters and technological conditions were designed and optimized by the use ofcomputer simulation. The appropriate operating parameters were: total plate number18, with8for reaction,10for distillation; reflux ratio1.3; pressure1.0MPa; the flowrate of acetic acid88kmol/h, the flow rate of liquid gas160kmol/h. Simulated basedon this condition, the composition of acetic acid at the top of column was150ppm, thepurity of sec-butyl acetate was up to63.1%.The refined process was simulated by Aspen Plus. Remove liquefied petroleumgas from the crude product by flash, and optimize the fraction of vaporization of flashto get the appropriate value0.3. The appropriate temperature was120℃.The product removed light component was feed to the first-azeotropic distillationcolumn. The appropriate operating parameters by the use of simulation were: totalplate number35, feed location27; reflux ratio1.7. Simulated based on this condition,the acetic acid of top of column was9.43×10^-6.The second-azeotropic distillation column was simulated by Aspen Plus. Theappropriate operating parameters by the use of simulation were: total plate number35,feed location19; reflux ratio1. Simulated based on this condition, the purity ofsec-butyl acetate was up to99.9%.