Pervaporation Membrane Separation Technology And Its Application In The Separation Of Water From Crude Ethyl Acetate

Ethyl acetate is an important chemical solvent and has been widely used in a wide range of industry sectors such as painting, coating, pharmacy, and perfume. Due to its low toxic level, applications of ethyl acetate are receiving increasing attention and ethyl acetate is gradually replacing solvents with higher toxic levels. In current industry practice, one of the more effective methods to produce ethyl acetate is based on esterification via catalysis distillation-reaction. In the esterification process, ethyl acetate is first withdrawn from the top of the distillation tower, while water flows out from the bottom. A demixer installed at the bottom of the tower is used to separate water and organic compounds. The separated organic compounds consist of ethyl acetate, alcohol, and acetic acid. They will then be redirected back to the tower and continue the chemical reaction. The crude product from the top, on the other hand, still includes a small quantity of water, which will reduce the quality and stability of ethyl acetate. As such, it is better to remove water in an effort to improve the stability of the crude ethyl acetate. The traditional technique to remove water from the crude product is distillation. However, this technique is not economically viable when dealing with such a miniature amount of water. This research is motivated to develop a better approach for water removal in the industrial production of ethyl acetate. The proposed approach uses hydrophilic polymer-vinyl-alcohol (PVA) membrane from the crude ethyl acetate via pervaporation separation.Membrane separation is an emerging technology. Pervaporation is one of the most active areas in the current membrane research, which targets the separation of liquid mixtures. This method is particularly suitable for the removal of a small quantity of water from organic solution or volatile organic compounds from aqueous solutions. It has the advantages of saving energy and being convenience when compared with traditional separation technique.In our research, four methods have been used to improve the PVA/PAN composite membrane. The experimental results indicate that the fastest rate of dehydration and the best operating stability can be achieved if the PVA/PAN composite membrane mended by theφ(aldehyde acetal)=6% solution is employed. The effects of feed temperature, ethyl acetate mass fraction, and operation time on the performances of the PV membrane are investigated. The results show that the PVA/PAN composite membrane achieves better PV performance for the separation of ethyl acetate /water under high mass fraction of ethyl acetate water concentration in the feedl4.87%. The relationship between remaining water concentration in the feed with time in ethyl acetate/water binary system at 50℃can be summarized by :water %=7.9×10^-5Ï„² -0.0737Ï„+14.9868This result can be used to predict the time needed to remove a certain quantity of water and complete the production task as designated.Our experiments have also considered the separability of membranes in the 4-element mixture system of water, ethyl acetate, alcohol, and acetic acid. Our experimental findings indicate that the fundamental patterns of influence are similar to those found in the 2-element mixture system consisting of water, ethyl acetate. The key difference lies in the fast that the separation factor in the 4-element mixture system tends to decrease as time progresses. The reason for this difference is that the membrane demonstrates stronger selective filtering effect on alcohol or acetic acid than ethyl acetate. Nonetheless, the membane's separation factor for water in the 4-element mixture system is still relatively strong.In conclusion, the PVA/PAN composite membrane modified by aldehyde provides a practical approach to purify the crude ethyl acetate in industry settings. PVA membrane has excellent selectivity to water and high penetrating quality; it also achieves high stability under various experimental conditions. The reported study proposes the use of advanced Pervaporation in combination with the production process of catalysis distillation-reaction. It leads to an integrated system of reaction and separation, which promises to provide a new technical foundation for the optimization of the industry-strength esterification system.