Supercritical CO2 fractionation of bio-oil produced from wheat–hemlock biomass

The biomass i.e. wheat–hemlock used in this study was first characterized for its composition. The physical and chemical characterization of biomass was estimated using proximate analysis, calorific value, crystallinity, devolatilization behaviour, ultimate analysis, ICP-MS of ash, FT-IR, XRD, CHNS, and HPLC analysis. For commercial purpose the same biomass was used for conversion to bio-oil by fast pyrolysis process. Therefore, in order to investigate its composition, the bio-oil was also characterized using proximate analysis, calorific value, whereas the chemical composition of the bio-oil was estimated using CHNS, 1H NMR, GC-FID and GC/MS. The bio-oil obtained from wheat–hemlock biomass was supplied by Advanced Biorefinery Co. and after the analysis, its composition has been determined. It contains a mixture of hydrocarbons, pyranoids, furanoids, benzenoids and fatty acids/alcohols with 45% of water, which forms azeotrope with organic polar compounds. The supercritical CO2 (SC-CO2) is an advanced method for selective extraction of valuable chemicals from bio-oil without solvent residue. The organic fraction of the bio-oil was isolated by SC-CO2. It was observed that SC-CO2 fractions collected at 10 and 25 MPa pressure were enriched with furanoids, pyranoids and bezenoids. Similarly the bio-oil was also fractionated by conventional column chromatographic method and the yields and chemical compositions were compared with fractionated bio-oil obtained using SC-CO2.