Conversion and extracting bio-oils from rod-shaped cornstalk by sub-critical water

Abstract

The rod-shaped cornstalk sample was selected to investigate the generation of bio-oils (including water-soluble oil and heavy oil) by sub-critical water under different reaction temperatures (240–350°C) and extraction times (0–120min). The gas, the water-soluble oil extracted by n-hexane and heavy oil extracted by acetone from the residue were collected and disposed, respectively. The gas chromatography-mass spectrometer (GC–MS) analysis of water-soluble oil showed that phenols were the major compounds. The pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) analysis of heavy oil showed that it was primarily consisted of phenols, carboxylic acids, aromatic ketones, and nitrogen- and sulfur-containing compounds. The results demonstrated that the optimum liquefaction condition in sub-critical water was at 260°C and 15min, and the highest bio-oil yield could be reached 33.00%. The results of experiment indicated that the structure of the lingocellulose (lignin, cellulose and hemicellulose) in the rod-shaped cornstalk was able to be broken down by sub-critical water at relatively low temperature and short extraction time without any catalyst and organic reagent.