Enzymatic Reactive Distillation For The Production Of N-butyl Acetate

Reactive distillation is the integration of the reaction and separation steps into one operational unit,which contributes to overcome equilibrium-limited and/or inhibited by the product of the reaction.The biocatalytic reactions are Efficiency and environmental.In order to find and test an appropriate method for the intensification of enzymes in a reactive distillation column,we develop a special type to prepare n-butyl acetate by enzymatic with reactive distillation.This method is a combination of reaction distillation field and biocatalytic field.It belongs to the interdisciplinary field and is the technological innovation of chemical process intergration and optimization.In this work:Candida antarctica lipase B(CALB)was immobilized by entrapment in a hydrophobic silica xerogel and introduced as granulate into the catalytic packing steel ? ring.By optimizing the amount of silane precursor,enzyme addition,crosslinking agent and water in the immobilized enzyme process,the most suitable immobilization ratio is determined,so that the enzymatic properties of the immobilized enzyme can be applied to the reactive distillation.The results showed that the immobilized enzyme activity is 490 U/g,the activity of relative free enzyme was 97.3%,the immobilization rate of protein is 96% and the protein content is 3.4 mg/g.The transesterification of ethyl acetate with n-butanol in the presence of immobilized CALB is considered in a batch stirred tank reactor.The reaction kinetics is experimentally determined for different stirring rate,catalyst dosage,concentration and temperature.The suitable operating conditions are determined and a pseudo homogeneous kinetic model is established.Process simulations are carried out with Aspen Plus,and process optimization are conducted to the preparation process of n-butyl acetate.by which the appropriate condition of the rectifying process of transesterification reaction to prepare n-butyl acetate is obtained.The reaction section plate number is 11,the distillation section plate number is 7,the extraction section plate number is 8,the operating reflux ratio is 6,the molar ratio of ethyl acetate to n-butanol is 3:1.The conversion of the n-butyl alcohol to 99.3%,and the mass concentration of n-butyl acetate is 99.7%.Reactive distillation experiments are carried out in a vitreous column setup comprising of steel ? ring coated with the catalytic silica gel.The experimental results of enzymatic reaction distillation are consistent with the results simulated on Aspen Plus,and the numerical error is within the allowable range.These results clearly demonstrate that lipase CALB can be applied in a continuously operated reactive distillation column.