6181 r2009 American Chemical Society pubs.acs.org/EF Energy Fuels 2009, 23, 6181–6188 : DOI:10.1021/ef900663a Published on Web 10/07/2009 Supercritical CO 2 Fractionation of Bio-oil Produced from Mixed Biomass of Wheat and Wood Sawdust P. K. Rout, † M. K. Naik, † S. N. Naik, ‡ Vaibhav V. Goud, § L. M. Das, ^ and Ajay K. Dalai* ,† † Catalysis and Chemical Engineering Laboratories, Department of Chemical Engineering, University of Saskatchewan, Saskatoon, SK, Canada S7N5C5, ‡ Center for Rural Development and Technology, Indian Institute of Technology, Delhi, § Department of Chemical Engineering, Indian Institute of Technology Guwahati, Assam, and ^ Center for Energy Studies, Indian Institute of Technology, Delhi Received June 29, 2009. Revised Manuscript Received September 7, 2009 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 CO 2 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, 1 H 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-CO 2 ), and it was observed that the first fraction of SC-CO 2 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-CO 2 fractions. 1. Introduction Bio-oil produced from biomass is a potentially promising alternative fuel for the transport sectors owing its ecological advantage. These renewable energy resources become quickly popularized due to their lack of environmental risks and pollution. However, some of the inefficient conversion pro- cesses such as wood furnaces release more pollutants than natural gas furnaces. Biomass materials are natural high molecular substances composed of carbon, hydrogen, oxygen, and nitrogen. Biomass such as wood waste, sawdust, and agriculture waste can be easily acquired. Biomass is seen as one of the best options for providing a renewable fuel and also has the added advantage of begin CO 2 neutral. This is due to CO 2 intake by plants from atmosphere due to photosynthesis and subsequent release of this CO 2 during the biomass con- version process. In addition to their sustainable favorability, they are, in general, more evenly distributed over earth’s surface than fossil fuels and may be exploited using less capital-intensive technologies. Hence, they increase the scope for diversification and decentralization of energy supplies and the achievement of energy self-sufficiency at a local, regional, and national level. 1 Lignocelluloses biomass represents a renewable source of raw feedstock for conversion into biofuels and chemicals. 2 The availability of biomass in the world is 220 billion oven- dry ton (odt) per year or 4500 EJ (10 18 J). 3 It is world’s largest and most sustainable energy resource. Due to the high energy content of biomass, its utilization will lead to reduction of fossil fuel consumption and greenhouse gas emissions and partially solve the dependence on fossil fuels in many coun- tries. 4 Biomass consists of cellulose, hemicellulose, and lignin. The use of renewable resources for fuel, such as bio-oil derived from lignocellulosic biomass, has great potential to partially replace petroleum fuel. The characterization of lignocelluosic biomass is important to determine its feasibility for the biofuel production. Selected biomasses such as wheat straw and wood sawdust are abundant in Canada. For example, Saskatchewan pro- duces 7.6 million ton of wheat annually based on the average taken over the production of the past 10 years. 4 In Canada, the average annual wood cut has been estimated at 167.5 million m 3 creating over 60 million ton of residue. 3,5 These were used *Corresponding author. E-mail: ajay.dalai@mail.usask.ca. Phone no.: 1 (306) 966 4771. Fax no.: 1 (306) 966 4777. (1) Jones, M. R. Biomass for energy. In Biomass handbook; Kitani, O., Hall, C. W., Eds.; section 1.2.2. (2) Sanderson, M. A.; Agblevor, F.; Collins, M.; Johnson, D. K. Biomass Bioeng. 1996, 11, 365–370. (3) World energy council. Survey of energy resources, 20th ed.; Elsevier Ltd: Oxford, 2004; p 267. (4) Agricultural statistics. Information of Government of Saskatch- ewan website. (5) Mohan, D.; Pittman, C. U., Jr; Steele, P. H. Energy Fuels 2006, 20, 848–889.