Production and characterization of bio-oil and biochar from ablative pyrolysis of lignocellulosic biomass residues

Abstract

Agricultural residues are one of the large untapped sources of bio-energy in Thailand, with over 30 million tons available per year. They may be utilized to generate renewable liquid and solid fuels. In this work, pyrolysis of lignocellulosic biomass residues (corncobs, coconut shells, and bamboo residue) was carried out in an ablative pyrolysis reactor with rotating blades. Influences of inert carrier gas flows (5–15 L/min) and rotating frequency (4–8 Hz) at a fixed hot plate temperature of 500 °C on generating bio-oil were investigated. Characterization of bio-oil as well as biochar products was performed. Maximum bio-oil yield was found to be about 50% w/w for coconut shell at 5 L/min of flowrate and 8 Hz of the rotating frequency, and 45% w/w for bamboo residues at the same condition. For corncob, the highest bio-oil yield was 72% w/w at 5 L/min of flowrate and 6 Hz of the rotating frequency. Solid char yields were around 23–28% w/w. The heating values of the liquid oil and solid char were about 20–25 and 23–30 MJ/kg, respectively. Rotating blade ablative reactor was able to generate high yields of bio-oil for agricultural residues. The main compounds of the bio-oil obtained were phenolics, including furfuran, organic acids, aldehydes, alcohols, ethers, and ketones.