Optimization Of Process Parameters For Ethyl Acetate Catalytic Distillation Using Response Surface Methodology

Ethyl acetate is an important organic solvent used in the adhesive and pharmacy industry and is synthesized in domestic industry mainly via the esterification reaction of ethanol with acetic acid using concentrated sulfuric acid as catalysts. Recently, novel solid esterification catalysts have tremendous potential to replace sulfuric acid. Sodium bisulfate has some advantages compared to sulfuric acid such as less corrosion of equipment, higher catalytic activity and less side reactions. However, the application of sodium bisulfate is confined, because it can’t be made into catalyst packing or configuration due to its small particle size and water-solubility. According to the features of sodium bisulfate, the process with a novel method for feeding a mixture of solid catalyst and acetic acid was proposed. In this paper, catalytic distillation column was designed and built, measurement and control system of a small scale distillation column based on LabVIEW was developed, and experiments were conducted by combing the sing factor methodology and response surface methodology based on central composite design. The experiment results proved that the catalytic distillation process with the method for feeding a mixture of sodium bisulfate catalyst and acetic acid was practicable and efficient. The specific research content as follows(1) This paper developed measurement and control system of a small scale distillation column based on LabVIEW. The system achieved the functions of collection, display and storage of temperature and pressure experimental data, and controlling the power of the heating jacket, switching of total reflux and partial reflux, controlling of the speed, start-stop, full speed&normal speed, positive&negative of the pumps for materials’feed-in and feed-out, and a total of nine measurement and control points basically meet the experimental requirements.(2) The catalytic distillation column and auxiliary devices were designed and built for the synthesis of ethyl acetate by direct esterification with sodium bisulfate as catalysts. According to processing capacity of the laboratory test device, the paper designed the distillation column, the reflux ratio control device, the bottom heater, the monitor, solid-liquid mixing and feeding device, cooling system and feeding system. In view of the characteristics of sodium bisulfate, the method for feeding a mixture of solid catalyst and acetic acid was adopted in the catalytic distillation, in which the powdered catalyst and the liquid flowed together in the column. The catalyst has no need to be made into catalyst packing or configuration. In addition, using area normalization method, correction factors relatively of each component were measured and column plates measuring experiment were conducted.(3) Process optimization experiments of ethyl acetate in a catalytic distillation column were carried out using Response Surface Methodology, which is above all used in esterification process of ethyl acetate. Firstly, single factor experiments were conducted to analyze the influence of five operating parameters on the conversion of ethanol and the parameters are catalyst dosage, reboiler duty, reflux, acetic acid feed flow, acetic acid/ethanol ratio. According to the results of single factor experiments and hydraulics performance of distillation column, reboiler duty was fixed to68W and catalyst dosage was fixed to2wt.%with respect to acetic acid. Experiments were designed based on Central Composite Design for analyzing three operating parameters, which were reflux, acetic acid feed flow, acetic acid/ethanol ratio. The optimum conditions were determined to be3.3reflux,3.2mol/h acetic acid feed flow and3.1acetic acid/ethanol ratio. The conversion of ethanol is88.67%Compared to the conventional esterification process of ethyl acetate production, the conversion-per-pass was increased by7%.