Selective esterification of glycerol with acetic acid to green fuel bio-additive over a lignosulfonate-based renewable solid acid

Using waste biomass as feedstock to obtain high value-added chemicals has attracted increasingly more attention from the viewpoint of sustainable development. A novel renewable bio-based solid acid (LFuS) was prepared by a two-step sulfonation of the phenol-formaldehyde condensation product of sodium lignosulfonate (LS-Na) and furfural derived from industrial and agricultural organic wastes. LFuS was then firstly employed as a catalyst for the selective esterification of glycerol (GL) with acetic acid (HOAc) to produce a fuel bio-additive, a mixture of glycerol diacetates (DAG) and glycerol triacetate (TAG). Using LFuS achieved a 98.0% conversion of GL with the selectivity to DAG + TAG of 94.1% under milder conditions. Additionally, the obtained LFuS also exhibited an excellent reusability in this reaction, and no loss in glycerol conversion was observed after five cycles, with the corresponding selectivity to DAG + TAG only decreasing from 94.1% to 90.0% after five cycles. The high concentration of acid sites and the polyphenolic structure of LFuS are responsible for its excellent catalytic performance and reusability in selective esterification of glycerol reaction.