Distillation and Isolation of Commodity Chemicals from Bio-Oil Made by Tail-Gas Reactive Pyrolysis

Owing to instabilities, very little has been accomplished with regard to simple cost-effective separations of fast pyrolysis bio-oil. However, recent developments in the use of tail-gas reactive pyrolysis (TGRP) (Mullen, C. A.; Boateng, A. A.; Goldberg, N. M. Energy Fuels 2013.) provide higher quality bio-oils that are thermally stable. We used fractional distillation to isolate compounds from bio-oil produced by TGRP. All bio-oils produced from TGRP contained significantly less acid (0.2–4% total), trace amounts of aldehydes, and significantly higher concentrations of hydrocarbons and phenolics (5–20% each). One TGRP bio-oil rich in naphthalenes yielded the greatest mass of distillates (close to 65%). Using atmospheric distillation alone, we recovered the most distillates from another phenol-rich TGRP oil. Compared to traditional bio-oils, distillation of TGRP oils yielded three times more organic compounds; the yield improvement increases to a factor of 10 when the contribution of acetic acid is removed from consideration. Greater deficiencies in distillation yield occur with higher acids content (4 wt % acid). We categorized distillates according to boiling temperature and chemical components: benzene–toluene–xylenes (BTX), styrene, indene, pyridine, phenols, naphthalenes, acetic acid, and fluorene/anthracene. The relatively narrow product distributions allowed for the isolation of pure naphthalene by recrystallization from a naphthalene-rich fraction. Thermodynamic computation of the TGRP distillation profiles correctly predicted the experimental results, except when acid content equaled 4 wt %. The quality of the TGRP bio-oils allows for insertion into existing refineries, as well as the required Modeling and scale-up.