Experimental study of glycerol etherification with C5 olefins to produce biodiesel additives

- 51% glycerol conversion was achieved optimizing glycerol/tert-amyl alcohol mixtures.
- With glycerol/isoamylenes/tert-amyl alcohol mixtures, 69% conversion was achieved.
- Temperature, reaction time and molar ratio play a major role in glycerol conversion.

The etherification of glycerol with isoamylenes has been studied employing twelve catalytic ion-exchange resins in order to establish the basis for a novel green process coming from this renewable source. Two compositionally different experimental approaches to transform glycerol in biodiesel additives were considered i.e. using glycerol (G), tert-amyl alcohol (TAA) and/or isoamylenes (IA) in variable molar ratios. Reactions were carried out in a stainless steel batch minireactor at temperatures between 313 and 348 K, autogenous pressure to 1.5 MPa and 1-24 h reaction time. The influence of initial molar ratio of reactants, temperature, pressure, reaction time and the catalyst employed were evaluated to optimise the process and attain the maximum conversion of glycerol. Optimization of mixtures of glycerol with TAA resulted in maximum glycerol conversion attaining 51% whilst greater glycerol conversions close to 70% were achieved using mixtures of glycerol/isoamylenes/tert-amyl alcohol.