Supercritical CO₂Fractionation of Bio-oil Produced from Mixed Biomass of Wheat and Wood Sawdust

Abstract

Interest in the biomass as a source of fuel, chemicals, and materials is growing fast. The bio-oil derived from biomass is attractive due to its renewability and the fact that it is CO2 balanced and sulfur free. The physical and chemical characteristics of biomass (i.e. wheat−wood sawdust) were estimated using proximate analysis, calorific value, crystallinity, devolatalization behavior, and ultimate analysis. Inductively coupled plasma mass spectroscopy (ICP-MS) of ash, X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and composition of water-soluble sugars of mixed biomass (wheat−wood sawdust) were also carried out. For commercial purposes, the same biomass was used for conversion to bio-oil by fast pyrolysis process. In order to investigate its properties, bio-oil was systematically characterized using different measurements such as proximate analysis and calorific value, whereas the chemical composition of bio-oil was estimated using CHNS, 1H nuclear magnetic resonance (NMR), gas chromatography flame ionization detection (GC-FID), and GC/MS. The bio-oil obtained was a mixture of hydrocarbons, pyranoids, furanoids, benzenoids, and fatty acids/alcohols along with 45% of water. The high amount of water present in bio-oil forms an azeotrope with organic polar compounds. The organic fraction of the bio-oil was isolated by supercritical carbon dioxide (SC−CO2), and it was observed that the first fraction of SC−CO2 extraction collected at 25 MPa was enriched with furanoids (9.9%), pyranoids (9.0%), and bezenoids (44.8%). The organic fraction present in the bio-oil was extracted by organic solvents, and the yields and chemical compositions of products were compared with those obtained from SC−CO2 fractions.