Energy & Fuels, Vol.33, No.4, 3248-3256, 2019
Hydrothermal Liquefaction of Lignocellulosic Biomass Using Potassium Fluoride-Doped Alumina
Hydrothermal liquefaction (HTL) of spruce wood was performed without and with the use of a potassium fluoride-doped alumina catalyst (KF/Al2O3) in a bench-top reactor. HTL runs were performed at 250, 300, and 350 degrees C with residence times of 15, 30, and 60 min. The effects of the catalyst at different catalyst loadings (in concentrations from 10 to 40 wt % of the lignocellulosic biomass) on the bio-oil and solid residue yields as well as their properties were investigated. The use of the catalyst increased the bio-oil yields over twofold and reduced char yields. Gas chromatography-mass spectrometry analysis revealed that the bio-oil from the noncatalytic and catalytic runs consisted of aldehydes, ketones, phenols, acids, and esters. Among these components, phenolic compounds were dominant in both the noncatalytic and catalytic runs. The relative yields of phenolic compounds increased with catalyst use. The highest heating value was estimated to be approximately 29 MJ/kg. The boiling point distributions of the bio-oils from both runs revealed that the total naphtha fraction (light and heavy) was comparable to that of crude oil.