One-pot chemo-enzymatic conversion of D-xylose to furfuralcohol by sequential dehydration with oxalic acid plus tin-based solid acid and bioreduction with whole-cells.

In this study, organic acid could be used as co-catalyst for assisting solid acid SO42-/SnO2-argil to convert hemicellulose-derived D-xylose into furfural. The relationship between pKa of organic acid and turnover frequency (TOF) of co-catalysis with organic acid plus SO42-/SnO2-argil was explored on the conversion of D-xylose to furfural. Oxalic acid (pKa = 1.25) (0.35 wt%) was found to be the optimum co-catalyst for assisting SO42-/SnO2-argil (3.6 wt%) to synthesize furfural from D-xylose (20 g/L) at 180 °C for 20 min, and the furfural yield and TOF could be obtained at 57.07% and 6.26 h-1, respectively. Finally, the obtained furfural (107.6 mM) could be completely biotransformed to furfuralcohol by recombinant Escherichia coli CCZU-K14 whole-cells at 30 °C and pH 6.5 in the presence of 1.5 mol glucose/mol furfural and 400 mM D-xylose. Clearly, this strategy shows high potential application for the effective synthesis of furfuralcohol from biomass-derived D-xylose.