A Superstructure-Based Lignin Valorization Process Optimization Model for Lignocellulosic Biorefineries through Biological Upgrading

This study presents an optimization framework to identify economically viable pathways for lignin valorization in biorefineries that employ biological upgrading. The economic potential for converting lignin from hardwood, softwood, and herbaceous plants into valuable bioproducts is evaluated. The research indicates that the production of 2-pyrone-4,6-dicarboxylic acid (PDC) from hardwood is the most economically promising, with an estimated net present value of $771.41 million and an internal rate of return of 19.73% through dilute acid pretreatment, base-catalyzed depolymerization, and PDC fermentation. Capital costs represent a large portion of the total expenses across all scenarios. Revenue from woody feedstocks is largely derived from lignin-based products, while for herbaceous plants, coproducts (fermentable sugars) are the main revenue contributors. The analysis provides insights for the development of lignin valorization biorefineries and guides the chemical industry toward a more sustainable use of renewable carbon sources.