Comparative liquefaction investigation of pine woodchips using water and tetralin as deoxygenation and hydrogenolysis agents

This study investigated the liquefaction of pine woodchips using water and tetralin as solvents to evaluate their effects on product yield and composition. Experiments were conducted at 350 °C and 400 °C with varying solvent/biomass ratios (1–3 mL/g), followed by analysis of the resulting solid, liquid, and gas products. Results show that both conversion and liquid yield increase with temperature and solvent volume. Water achieved slightly higher conversion, while tetralin significantly enhanced liquid yield, reaching 64.72%, about 3.5 times higher than water. Solid residues from both processes were carbon-rich with lower H/C and O/C ratios than the feedstock, with slight differences between water and tetralin derived residues. Gas analysis revealed that water promoted higher CO 2 production (up to 39.7%), whereas tetralin favored the formation of C1–C4 hydrocarbons (up to 9.6%). Methane was the dominant gaseous product, with moderate variation in gas yields based on solvent type, volume, and temperature. Tetralin liquefaction at 400 °C with 3 mL/g solvent produced the highest maltenes and hydrocarbon-rich fractions, more than water. Tetralin facilitated the generation of both aliphatic and aromatic hydrocarbons while minimizing the formation of polycyclic aromatic hydrocarbons (PAHs). In contrast, water yielded fewer hydrocarbons and PAHs. Increasing tetralin volume also promoted heavier aromatic compounds.