The feasibility of diol-assisted fractionation for lignin-first biorefinery: An integrated process design and...

Lignin-first biorefinery strategies have emerged as powerful method to prevent undesired recondensation during biomass fractionation, thereby enabling the sustainable valorization of lignin and cellulose. Among these, the diol-assisted fractionation (DAF) operates via stabilization of reactive aldehyde intermediates with simple diols, thus without the need of heterogeneous catalysts or pressured H₂. This study presents the first conceptual process design of a specific DAF process, targeting lignin oil production as well as carbohydrates valorization at an industrial scale. We systematically evaluated the economic and environmental performance of this process through integrated process simulation, techno-economic analysis (TEA) and life cycle assessment (LCA). TEA indicates a minimum selling price of refined lignin oil (MSP-RLO) produced via DAF as $543.2/t, significantly lower than the reductive catalytic fractionation (RCF) ($853.5/t), primarily due to reduced total capital investment (TCI) associated with milder processing conditions and the absence of hydrogenation. LCA further reveals the strong environmental benefits, with the DAF process achieving a negative carbon footprint (-1.13 kg CO₂-eq./kg lignin oil), attributed to the co-production of valuable carbohydrate pulp and the resulting environmental burden allocation. Sensitivity analysis identifies the solvent consumption and feedstock costs as the most influential factors affecting economic performance, while Monte Carlo simulations indicate that increasing the market price of lignin oil to $2,000/t could reduce the investment risk of the production process to below 10%. This work establishes a viable and scalable lignocellulose fractionation platform aligned with the evaluation of both the economic and environmental performance, advancing the lignin-first valorization strategy.