Dehydration – purification of aqueous ethyl alcohol by adsorption over molecular sieves: continuous operation

Abstract

Fuel reserves are fast being depleted; hence, alternatives to fossil fuels need to be constantly explored. Ethyl alcohol (ethanol) is an important fuel substitute because it can be blended with the present-day fuels, can be produced via agricultural routes, is comparatively cheap and the technology of production is well known. Fermentation is used to produce dilute (<20 mass %) ethanol, which needs purification. Ethanol forms a minimum boiling azeotrope with water, and hence, advanced distillation methods are employed for purification. Most of these are costly and hence alternative methods of separation are employed: extraction, membrane separation and adsorption.This work has used adsorption for the dehydration – purification of the aqueous mixture of ethanol over various adsorbents. Stainless steel (SS 316 L) column fitted with a sintering plate was employed for adsorption using various adsorbents. Adsorption studies proved that it is possible to obtain high purity (>99.7 mass %) ethanol with molecular sieves. The possibility of continuous operation was successfully demonstrated in this work.