Ethyl tertiary butyl ether (ETBE) is a high-octane bioethanol product obtained mainly by making the ethanol react with isobutylene (a byproduct of oil refining) under the effect of heat and various catalysts. It is consequently considered as being partially renewable.

ETBE has technological and functional features that are very like and distinctly better than those of the alcohol it is obtained from. Moreover, it lacks the latter’s problems of volatility or miscibility with petrol and it features a high octane number.

Being an ether, it contains oxygen in the molecule, and this enables it to help improve the vehicle’s emissions of pollutants. A recent paper (Da Silva et al., 2005) conducted a study on the effects of the anti-detonating properties and Reid vapor pressure (RVP) of petrols mixed with various additives, concluding that adding ETBE improves the mixture’s anti­detonating properties and reduces the vapor pressure without interfering with the volatility needed to start a cold engine.

ETBE obtained from bioethanol (also called bioETBE) offers the same benefits as bioethanol, i. e. a lower emission of pollutants, a higher octane number and a reduction in crude oil imports, without the technical and logistic problems posed by the alcoholic nature of bioethanol. BioETBE also contributes to the diffusion of biofuels in the transport sector.