(285b) Upgraded Bio-Oil Production from Sweet Sorghum through 2-Stage Hydrothermal Liquefaction

Yue, Y., University of Georgia
Mani, S., University of Georgia
Kastner, J., University of Georgia

Hydro-Thermal Liquefaction (HTL) technology is a promising method to convert high moisture lignocellulosic biomass into biofuels and platform chemicals at moderate temperature (280-370 °C) and pressure (10-25 MPa). Soluble sugars and benzene-type chemicals from sweet sorghum lignocellulose macromolecules (hemi-cellulose, cellulose and lignin) hydrolysis further decompose and cross react into solid residues, which significant reduce crude bio-oil yield. The main objective of this study was to investigate the two-stage liquefaction of sweet sorghum to selectively produce sugar mixtures and upgraded lignin derived bio-crude oil. In the first stage, biomass was treated below 280 °C to produce soluble sugar mixtures that were selectively hydrolyzed from cellulose and hemi-cellulose. Sugar stream contained mixtures of glucose, xylose,  arabinose, 5-hydroxymethyfurfural (5-HMF) and levoglucosan. Solid residues from 1st stage liquefaction contained more than 70 wt % lignin. In the second stage, lignin containing solid residues was thermally treated along with hydrodeoxygenation (HDO) upgrading process at 350 °C for 1 h with 5 wt % Ru/C. The upgraded bio-oil yield reached to 63 wt % and contained cyclopenten-1-one, ethyl-phenol, hexadecanoic acid and octadecanoic acid. The moisture and O/C ratio of upgraded bio-oil were 5 wt % and 0.1 respectively, which could meet the fuel specifications of petroleum crude oil for effective co-processing into drop-in biofuels and platform chemicals.