Ethyl Acetate Production from Ethanol

The process under analysis comprises three major sections: (1) Dehydrogenation; (2) Hydrogenation; and (3) Distillation.

Dehydrogenation. Fresh ethanol is vaporized, mixed with an ethanol recycle stream and then fed to the dehydrogenation reactor. This reactor is divided in multiple reaction zones and between them heat exchangers are placed to heat the reaction medium, thus maintaining the reaction temperature. The synthesis is achieved in two steps within this reactor, ethanol is first dehydrogenated into acetaldehyde and then acetaldehyde condensates into ethyl acetate.

Hydrogenation. The output from the dehydrogenation is partially condensed and a gaseous hydrogen-rich stream is separated. Part of the gaseous stream is recycled to the dehydrogenation. A second fraction is directed to the hydrogenation step and a third part is burned for fuel. In the hydrogenation reactor the condensate stream is contacted with hydrogen in the presence of a catalyst that preferably hydrogenates aldehydes and ketones to their corresponding alcohols, which are easier to separate from ethyl acetate.

Distillation. The polished stream is composed of mostly ethanol and ethyl acetate, also contains water. These three compounds can form a minimum boiling point azeotrope mixture. A pressure swing distillation column system is used in order to cross the azeotrope composition. In a first low-pressure column, ethanol and water are recovered from the bottoms and a top stream close to the azeotrope composition is directed to a high-pressure column. In the pressure this column is operated, the ethyl acetate azeotrope composition is lower than that of the feed, so it is possible to recover purified ethyl acetate from the bottoms. The recycle ethanol stream from the low-pressure column is purified for the removal of water and other impurities and recycled to the dehydrogenation step.