Hydrothermal pentose to furfural conversion and simultaneous extraction with SC-CO2 – Kinetics and application to biomass hydrolysates

This work explores hydrothermal d-xylose and hemicellulose to furfural conversion coupled with simultaneous furfural extraction by SC-CO2 and the underlying reaction pathway. A maximum furfural yield of 68% was attained from d-xylose at 230 °C and 12 MPa. Additionally missing kinetic data for l-arabinose to furfural conversion was provided, showing close similarity to d-xylose. Furfural yields from straw and brewery waste hydrolysates were significantly lower than those obtained from model compounds, indicating side reactions with other hydrolysate components. Simultaneous furfural extraction by SC-CO2 significantly increased extraction yield in all cases. The results indicate that furfural reacts with intermediates of pentose dehydration. The proposed processing route can be well integrated into existing lignocellulose biorefinery concepts.