Biomass pretreatment is a deliberately controlled conditioning and deconstruction stage in which the physical structure and chemical organization of lignocellulosic biomass are altered before thermochemical conversion. Its principal purpose is to reduce feedstock recalcitrance by modifying the interlinked cellulose–hemicellulose–lignin matrix, increasing the accessible surface area and porosity, reducing particle size or structural crystallinity where relevant, and facilitating the release, redistribution, or separation of organic and inorganic constituents ^[1][2]. Within thermochemical biomass conversion, pretreatment may involve physical, thermal, physicochemical, or chemical operations—such as milling, drying, torrefaction, steam-based treatments, hydrothermal processing, or chemical fractionation—provided that these operations condition the feedstock rather than constitute the primary conversion of biomass into pyrolysis vapors, syngas, biochar, or other final products ^[2][3]. Pretreatment is therefore distinct from thermochemical conversion itself: it prepares, fractionates, or structurally transforms the raw material, whereas conversion reactions principally depolymerize and chemically transform the conditioned biomass into targeted products. The specific pretreatment sequence and severity determine the resulting moisture content, particle morphology, component distribution, elemental composition, and chemical reactivity of the feedstock ^[3][4].