Techno-Economic Assessment of Two Process Routes for Lignin-Derived Alkylphenols and Aromatic Hydrocarbons

Lignin valorization processes are crucial for enhancing the economic feasibility of lignocellulosic biorefineries and improving waste management in the pulp and paper industries. This study performed a detailed techno-economic evaluation comparing two alternative lignin conversion pathways, focusing on the production of aromatics and alkylphenol: HydroDeOxygenation (HDO) and HydroDeOxygenation are preceded by HydroThermal Liquefaction (HDO + HTL). The analysis revealed that the integrated HDO + HTL is technically and economically superior, since it provides higher alkylphenol yield (30-35% by weight) and requires significantly less hydrogen, consuming only 22-28 kg of H₂ per ton of lignin. As a direct consequence of the superior yield and lower reagent consumption, the minimum selling price of alkylphenols via HDO + HTL is less than half of that obtained via HDO (1.52 compared to 3.47 EURO/kg, respectively). A comprehensive sensitivity analysis demonstrated that the lignin market price has the greatest impact on the minimum selling price of alkylphenols, resulting in variations of more than EURO 1/kg_AP. Even under the most favorable economic conditions for direct HDO (low hydrogen cost and free lignin), the HTL + HDO configuration remained the most economically convenient process solution. The results affirm that coupling HTL with HDO maximizes product yields and minimizes costs, securing profitability for lignin valorization.