Alkali-catalyzed liquefaction of pinewood sawdust in ethanol/water co-solvents

In this study, pinewood sawdust was liquefied in either ethanol/water co-solvents (50/50, wt./wt.) or pure water at 300 °C for 30 min and 10 wt% of feedstock loading, with or without the use of Na₂CO₃ or NaOH as a catalyst. The physical and chemical properties of liquefaction products (bio-crude oil and solid residue) were comprehensively characterized by FT-IR, GC-MS, elemental, GPC and TGA analyses. The results showed that the highest biomass conversion of approx. 98% was obtained in ethanol/water mixed solvents and without catalyst, along with a maximum yield of bio-crude oil (~48 wt%). The HHV of crude oil was within the range of 26–30 MJ/kg. The results indicated that the beneficial effect of ethanol on the bio-crude oil yield might be compromised by adding Na₂CO₃ or NaOH into the liquefaction system under investigated reaction conditions. As suggested by GPC analysis, the bio-crude oil obtained in ethanol/water co-solvents from both non-catalytic and catalytic liquefaction contained a slightly higher molecular weight than that obtained in pure water. Additionally, TGA results indicated that the boiling point distribution of bio-crude oil was only affected by ethanol addition, whereas, the effect of the catalyst was found to be minor. © 2020 Elsevier Ltd