Zeolite-assisted etherification of glycerol with butanol for biodiesel oxygenated additives production

This research was focused on the valorisation of glycerol, exploring the feasibility of an efficient route for oxygenated additives production based on its etherification with bio-butanol. A home-made BEA zeolite sample with a tuneable acidity has been proposed as the catalytic system, being tested in a stirred reac- tor under different etherification conditions. Although a reaction temperature as high as 200 °C resulted to be beneficial in terms of glycerol conversion (~90%), only by operating at milder conditions the prod- uct selectivity to glycerol-ethers can be better controlled, in order to obtain a bio-fuel complying with the requirements for mixing with fossil diesel or biodiesel, without any need of purification from large amount of by-products. A comprehensive identification of all the compounds formed during the reaction was performed by a GC-MS analysis, on the basis of the complex network of consecutive and parallel reaction paths leading not only to the desired ethers, but also to many side products not detected in similar acid-catalyzed reactions in liquid phase and not available in the most used mass-spectra libraries.