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

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 (0-120 min). 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 15 min, 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.