Ethyl Acetate Production from Ethylene and Acetic Acid

The process under analysis comprises two major sections: (1) Direct Addition; and (2) Separation.

Direct Addition. Fresh acetic acid from storage facilities is initially passed through a guard bed, which contain ion-exchange resins through which the liquid streams pass so as to entrap that metallic impurities. They could deactivate the catalyst over time. The liquid acetic acid exiting the bed is introduced into the middle region of a vaporizer, while fresh ethylene is fed to its bottom. The acid, as well as recycle streams fed to this piece of equipment, are vaporized. The vaporized feed stream is fed to four reactors set up in series, where the reaction is carried out in the presence of 12-tungtophosphoric acid catalysts. Water, in the form of steam, is also fed to the reactors to enhance the stability of the catalyst. Here, the reactant gases exiting from the first reactor are fed as the feed gas to the second reactor, and so on for subsequent reactors. In each reactor, when the reactant gases come into contact with the catalyst bed, part of the acetic acid is consumed in an exothermic reaction forming the Ethyl Acetate.

Separation. Once the reaction is complete, the gaseous reactor product is cooled and fed to a vapor-liquid separator, where a gaseous stream comprising mainly unreacted ethylene is withdrawn from the top and recycled to the reaction. The condensed liquid stream, containing ethyl acetate, unreacted acetic acid and light ends is the fed to the distillation section of the plant. In the distillation train, a stream of acetic acid is recovered as the bottoms product of the first column and also recycled to the reactor. The top product of such column follows to a decanter, where water is removed. The organic layer is further distilled to separate light-ends diethyl-ether (which is also recycled to the reactor after distillation) and acetaldehyde – purged from the process. Further distillation steps are required to separate ethanol, which is also recycled to the reactor after distillation, and heavy-ends that may be used as fuel. After those steps, high-purity Ethyl Acetate product is obtained.