A holistic valorization of lignocellulose remains challenging. It has long been used as a raw material for industries such as pulp and paper production and more recently in fermentative processes. But lignin itself remains a widely underused side product. Even though it has enormous potential as the largest bio-based source of aromatics, harsh process conditions in current industrial lignocellulose fractionation processes only deliver low-quality lignin that is mainly burned for energy recovery. The two-phasic, acid-catalyzed OrganoCat pretreatment offers a mild approach for the fractionation of plant biomass into its main components. Besides oxalic acid and 2,5-furandicarboxylic acid (FDCA) phosphoric acid has proven to be an efficient and recyclable catalyst. Hemicelluloses and other non-cellulosic polysaccharides are selectively hydrolyzed by the diluted acid and dissolved, while the cellulose-enriched solid pulp remains. During the process, lignin is disentangled and in situ extracted into a second organic phase consisting of 2-methyltetrahydrofuran. The cellulosic pulp shows good enzymatic convertibility into glucose which could be further converted, e.g. into bio-ethanol. The resulting lignin has a high β-O-4 content, which after depolymerization, might then be used as a fuel additive or in material application. Subsequent to the extraction, antisolvent precipitation of the lignin has been conducted to allow fractionation into more narrow size distributions. This allows to select fractions according to application demands. Lignin properties are influenced by plant selection as well as process conditions. Therefore, different plant biomasses were fractionated in the OrganoCat process. The resulting lignins differ in β-O-4 content, monomer composition, and size. By selection of plant type and optimal processing parameters, lignins can be produced tailored to a specific application.

Processing lignocellulose to extract lignin with designed properties

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.