Various hydrocarbons (n-hexane, cyclohexane, toluene, isooctane) and mixtures of them (binary, ternary or quaternary), as well as two different types of industrially produced naphtha (one obtained by direct distillation and the other from a catalytic cracking process), have been tested as candidate entrainers to dehydrate ethanol. The tests were carried out in an azeotropic distillation column on a semi pilot plant. The results show that it is possible to dehydrate bioethanol using naphtha as entrainer, obtaining as a result a fuel blend with negligible water content and ready for immediate use in motor vehicles. 1. Introduction In order to reduce the greenhouse gas emissions produced by the transportation sector, the use of biomass as a fuel or in a mixture with fossil fuels has been promoted by government legislative and financial initiatives. Among the various biofuel technologies, bioethanol has advanced the most. However, bioethanol obtained from the fermentation of biomass, which can come from different sources, needs to undergo several steps of purification. This bioethanol is produced in an aqueous media and must thus be dehydrated before it can be used as a fuel. European legislation permits a maximum of 0.3% water by weight fraction in the bioethanol to be blended with gasoline [1]. Even though the presence of a binary azeotrope in the water + ethanol mixture makes it impossible to separate ethanol and water in a single distillation step, there exists many other techniques [2] that can be used, alone or in combination, to dehydrate ethanol. Some of them include, but are not limited to: adsorption on molecular sieves [3], azeotropic distillation [4], pressure swing distillation [5], pervaporation [6], extractive distillation with ionic liquids [7], etc. Concretely, in recent years several papers have treated bioethanol dehydration through only simulation testing different techniques such as pressure swing absorption [8], hybrid processes (distillation/adsorption/vapor permeation [9], based on liquid-liquid extraction [10], heteroazeotropic distillation using a gasoline additive as entrainer [11], extractive batch distillation [12] or a heat-pump-assisted extractive distillation in a single step [13] and comparing them to the conventional process. Though all the techniques presented in these papers seem viable alternatives and arouse improvements in bioethanol dehydration process, the results presented are almost all based on
