Liquefaction of Fir Sawdust in Supercritical Ethanol with Dissolved Phosphotungstic Acid

Abstract

An environmentally benign approach is put forward with the focus on directly liquefying and depolymerizing Cunninghamia lanceolata (Lamb.) Hook. (Chinese fir) sawdust into ethyl levulinate (EL) under supercritical ethanol (scEtOH) conditions by using phosphotungstic acid (PTA) as a catalyst. The effects of parameters such as catalyst dosage, temperature, and reaction time on alcoholysis yield were investigated. The experimental results show that the biomass alcoholysis yield reached 95.35% with 0.5 g PTA as a catalyst at 260 °C for 30 min. Alcoholysis yield and quantitative content of EL depended on the catalyst. The light bio-oil was primarily composed of phenols, aldehydes, ketones, and esters. A high quantitative content of EL up to 20.82% (Ar, Relative abundance) was achieved, compared to 0.73% Ar when PTA was not added. Hence, scEtOH with dissolved PTA may offer novel media for both chemical reactions and biomass conversion technology as a replacement for environmentally undesirable organic solvents.