Biomass pre-extraction to increase sugar yields, lignin quality and to improve the overall performance of a lignocellulosic biorefinery.
As part of UNRAVEL, we successfully tested a new custom built biomass pre-extraction unit at TNO. ELEANOR, our biomass pre-extraction process that uses water and acetone, removes the non-lignocellulose compounds from complex lignocellulosic biomass prior to fractionation, with the goal to improve the fractionation performance, increase yields, improve the product quality. Additionally, extractives are obtained that can potentially be used in a number of products, among them fertilizers, fine chemicals and bio-active components. Valorising such extractives alongside lignin could significantly improve the economics and overall sustainability of a lignocellulosic biorefinery.
UNRAVEL could now show that the fractionation of complex biomass upgraded by pre-extraction increases the hemicellulose sugar yields and the lignin purity and significantly reduces the acid dose required during the fractionation process.
UNRAVEL fractionation of roadside grass with (LEX-RG) and without pre-extraction (RG).
Combining our ELEANOR™ pre-extraction process with our mild acetone organosolv FABIOLA™ process on complex residues as e.g. roadside grass, wheat straw, birch branches and almond shells resulted in 92- 95% recovery of cellulose in the pulp, 74-86% conversion of hemicellulose to oligo / monomeric sugars and 63- 81% isolation of a high purity lignin, significantly outperforming the fractionation of untreated feedstocks. Pre-extraction has also shown positive results when performed with a mixture of the mentioned biomass streams.
The TNO ELEANOR pre-extraction unit
These novel findings can have a significant impact on the future feedstock flexibility for a commercial-scale biorefinery plant. Increasing the biomass availability at lower prices and the valorisation of extractives could furthermore improve the economy and sustainability of biorefineries. Further research will be performed during UNRAVEL on extractives valorisation and on the sustainability of the overall value chains. A scientific publication detailing the pre-extraction results is currently in progress and will be shared on our UNRAVEL website.