(532m) Valorization of Glycerol from the Biodiesel Industry to Obtain Oxygenated Additives

The valorization of glycerol using chemical routes that could be operated in the biodiesel industry constitutes a promising procedure to achieve added-value products. An interesting option is the production of ethers, which may be used as fuel additives in diesel engines to improve combustion efficiency, reducing soot emissions and increasing cetane index. In this study, a purification route was applied to crude glycerol and its valorization by etherification was evaluated. The glycerol contents of the purified samples increased from ca. 10% to above 98% wt. Using the purified glycerol samples, etherification reactions were carried out with different alcohols (ethanol, propan-2-ol and 3-methyl-1-butanol) into a batch reactor, using Amberlyst 15 as catalyst, at autogenous pressure and solvent-free conditions. The influence of temperature, glycerol/alcohol molar ratio, catalyst load and reaction time was evaluated for the etherification reaction. Conversion values above 90% wt. were observed when using ethanol with catalyst/glycerol ratio of 0.02 (wt.) at 110ºC, and an excellent yield to ethers (up to 95.7% wt.) was obtained. Glycerol conversion values up to 95% wt. with selectivities of 76.2% wt. for monoether and 21.8 % wt. for diether were obtained when propan-2-ol was used as etherifying agent. For 3-methyl-1-butanol, a glycerol conversion up to 80% wt. was obtained. However, a low selectivity to ethers (~3% wt.) was observed.