Rapid and simultaneous production of furfural and cellulose-rich residue from sugarcane bagasse using a pressurized phosphoric acid-acetone-water system

In order to minimize hemicellulose (or cellulose) waste upon the simultaneous production of furfural and 5-hydroxymethylfurfural (or furfural and levulinic acid) from the hydrolysis of lignocellulose in one-pot acid/organic solvent systems, we have developed a novel pressurized phosphoric acid-acetone-water system (PPAWS) to convert hemicellulose into furfural with a high retention of cellulose. In the PPAWS (acetone/water = 7:3, v / v ) at 150 °C under 1.5 MPa nitrogen, furfural production (yield 45.8%), delignification (lignin removal rate 89.8 wt%), and cellulose-rich residue extraction (retention rate 72.9 wt%, purity 92.5 wt%) from sugarcane bagasse were achieved simultaneously in just 5 min. Gas chromatography–mass spectrometry analysis of the liquid products revealed that pressure significantly inhibits the generation of aldol condensation products, i.e., acetone self-condensation products and 4-(2-furyl)-3-buten-2-one from the condensation of acetone and furfural, and acetone was retained in large quantities. In addition, kinetic analysis revealed that the “xylose → furfural → degradation products” pentose-hydrolysis path occurs in the PPAWS and that the rate constant of the “xylose → furfural” step is significantly increased, which is a clear departure from the reaction conducted without additional pressure. Furfural degradation experiments confirmed that adding pressure also inhibits the degradation of furfural in the initial stage of the reaction. The PPAWS exploits the benefits of acetone for lignin removal and the promotion of furfural production, and can be easily integrated into advanced jet fuel production from the aldol condensation of furans and ketones.