Study On Reaction Distillationprocess Of Butyric Anhydride Produced By Acylation

In view of the increasing market demand in recent years for the butyric anhydride,the traditional process in production capacity,product quality and other aspects of the existence defects,so introduce reaction distillation technology to transform the traditional production process to achieve continuous production,with the lower cost of materials,produce consistent quality butyric anhydride while reducing investment in equipment and operating difficulty,achieve better economic and social benefits.In this paper,analyze the reaction mechanism,identified as a series of reactions and synthase and purified intermediate product,the concentration of butyl acetic anhydride refined more than 99%,measured the relationship between saturated vapor pressure and temperature,Antoine parameters A,B,C respectively 35.37247,16797.8,250.7983.Normal boiling point at atmospheric pressure acid butyric anhydride of Tb=185?,the average molar heat of vaporization 49814.2J/mol.Discussing acetic anhydride with butyric acid to synthesis butyric anhydride in reactor,acquired appropriate reaction conditions as follows:reaction temperature 70?,reaction time 40min,acid anhydride ratio of 2.5:1.Analyze the reaction mechanism,reaction kinetics was researched in the range of 50?-80?and kinetic equation was calculated at different temperatures,according to the dynamic model,the activation energy of the reaction obtained E_a1+,E_a1-,E_a2+,E_a2-were 59.16 KJ·mol^-1,51.57 KJ·mol^-1,49.96 KJ·mol^-1,54.83KJ·mol^-1.Selected NRTL-HOC thermodynamic equation,radfrac equilibrium stage model theory,the kinetic data previously obtained experimentally,to simulate the procession of butyric anhydride.Obtain optimum conditions of a continuous production of butyric anhydride reactive distillation were:reflux ratio were 1.5,acid anhydride feed ratio of 2.5,plate number 18,butyric acid feed location for the first five acetic anhydride feed position for the first 12 board.Experiments were carried out in the tower?50mm×1700mm?,which packed by a total height of about 1.5m layer of?3mm 316L stainless steel packing.The result showed that reflux ratio were 1.5,acid anhydride feed ratio of 2.5,butyric acid feed location is 2/5 from the top of tower,acetic anhydride feed position is 4/5 from the top of tower.Under these operate conditions:acetic anhydride conversion reach to 98.88%,the content of butyric anhydride bottoms was 83.802%,after refine,butyric anhydride reach to 99.9%.Experiments and simulate calculate values are in good agreement,the relative error<5%,in the allowable range,to verify the reliability of simulation calculation.