The fractionation of lignocellulose in its three main components, hemicellulose, lignin and cellulose pulp can be achieved in a biphasic system comprising water and bio-based 2-methyltetrahydrofuran (2-MeTHF) as solvents and oxalic acid as catalyst at mild temperatures (up to 140°C). This so-called Organo-Cat concept relies on selective hemicellulose depolymerization to form an aqueous stream of the corresponding carbohydrates, whereas solid cellulose pulp remains suspended and the disentangled lignin is to a large extent extracted in situ with the organic phase. In the present paper, it is demonstrated that biomass loadings of 100 g L −1 can be efficiently fractionated within 3 h whereby the mild conditions assure that no significant amounts of by-products (e.g. furans) are formed. Removing the solid pulp by filtration allows to re-use the water and organic phase without product separation in repetitive batch mode. In this way, (at least) 400 g L −1 biomass can be processed in 4 cycles, leading to greatly improved biomass-to-catalyst and biomass-to-solvent ratios. Economic analysis of the process reveals that the improved biomass loading significantly reduces capital and energy costs in the solvent recycle, indicating the importance of process integration for potential implementation. The procedure was successfully scaled-up from the screening on bench scale to 3 L reactor. The feedstock flexibility was assessed for biomasses containing moderate-to-high hemicellulose content.

With growing interest in the biomass value chain, a multitude of reactions are proposed in literature for the conversion of biomass into a variety of biofuels. In the early design stage, data for a detailed design is scarce rendering an indepth analysis of all possibilities challenging. In this contribution, the screening methodology process network flux analysis (PNFA) is introduced assessing systematically the cost and energy performance of processing pathways. Based on the limited data available, a ranking of biorefinery pathways and a detection of bottlenecks is achieved by considering the reaction performance as well as the feasibility and energy demand of various separation strategies using thermodynamic sound shortcut models. PNFA is applied to a network of six gasoline biofuels from lignocellulosic biomass. While 2-butanol is ruled out due to a lack in yield and selectivity, iso-butanol and 2-butanone are identified as economically promising fuels beyond ethanol. Topical area: Process Systems Engineering.

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