A Comprehensive Review on Biomass Valorization Through Thermochemical Pathways: Product Properties and Usage of Artificial Intelligence

Biomass valorization plays a vital role in achieving carbon neutrality and circular economy frameworks. Owing to its carbon rich structure, biomass represents a promising feedstock to produce bio-based hydrocarbons via biological and thermochemical pathways. While biological conversion routes have been extensively studied, their deployment at commercial scale is constrained by high capital costs and low product yields. In contrast, thermochemical conversion technologies are increasingly being explored as viable largescale biomass valorization routes. This review presents a comprehensive assessment of thermochemical pathways, with particular emphasis on hydrothermal liquefaction (HTL). HTL enables the efficient conversion of wet and heterogeneous lignocellulosic biomass without energy intensive drying pretreatments. The review critically examines the formation and physicochemical properties of the two main HTL products, namely liquid biocrude and solid hydrochar. Special attention is devoted to challenges associated with biocrude quality, particularly its high oxygen content, and corresponding upgrading strategies. Additionally, the diverse applications of hydrochar for energy recovery, soil amendment, and heterogeneous catalyst synthesis are discussed. The article also compares the technology readiness levels of thermochemical conversion routes and highlights the growing role of artificial intelligence and machine learning in process modelling and optimization. Finally, future research directions are identified, emphasizing design by specification strategies and physics informed AI to enable scalable, autonomous biomass conversion technologies.