| Bio-energy is renewable and clean (with trace amount of sulfur and neutral in terms of CO2 emission), and abundant in resource, thus it could be a securable and sustainable energy for future. Due to the declining reserve of light crude oil, there is increased interest in producing bio-fuels (bio-ethanol, bio-diesel and bio-oils) from biomass resources. Bio-crude, produced from lignocellulosic biomass/wastes by high-pressure direct liquefaction, has been found more advantageous than conventional bio-oil generated by pyrolysis since a bio-crude normally contains a greater heating value than pyrolysis oil. Bio-crude has a potential to be upgraded into high quality fuel oils or transportation fuels by hydro-treatment.;As Part-I of this thesis work, hydro-liquefaction of a woody biomass (birch powder) in sub-/super-critical methanol without and with catalysts was investigated with an autoclave reactor at temperatures of 200-400°C and initial pressure of hydrogen varying from 2.0 to 10.0 MPa. The liquid products were separated into water soluble oil and heavy oil (as bio-crude) by extraction with water and acetone. Without catalyst, the yields of heavy oil and water soluble oil were in the ranges of 2.4-25.5 wt% and 1.2-17.0 wt%, respectively, depending strongly on reaction temperature, reaction time and initial pressure of hydrogen. The optimum temperature for the production of heavy oil and water soluble oil was found to be at around 350°C, while longer residence time and lower initial H2 pressure were found to be favorite conditions for higher oil production. Addition of a basic catalyst, such as NaOH, K2CO3 and Rb2CO3, significantly promotes biomass conversion and increases yields of oily products in the treatments at temperatures less than 300°C. The yield of heavy oil is as high as 30 wt% for the liquefaction operation in the presence of 5 wt% Rb2CO3 at 300°C and 2 MPa of H2 for 60 min. The heavy oil product consists of a high concentration of phenol derivatives, esters and benzene derivatives, and has higher carbon content, a much lower concentration of oxygen content, and a significantly increased heating value (>30 MJ/kg) compared with the raw woody biomass.;In the Part-II of this research, hydrodeoxygenation (HDO) of bio-crude was investigated using phenol as the model compound in supercritical hexane at temperatures of 300-450°C and initial pressure of hydrogen 5.0 MPa with MgO-supported sulfided CoMo with and without phosphorus as the catalyst promoter. The oily products after hydro-treatment were characterized by GC/MS and FT-IR. Both MgO-supported catalysts proved to be effective for hydrodeoxygenation of phenol leading to significantly increased yields of reduced hydrocarbon products, such as benzene and cyclohexyl-aromatics, at temperatures higher than 350°C, while CoMoP/MgO showed superior activity in HDO of phenol. In the presence of CoMoP/MgO for 60 min and at 450°C, the treatment of phenol yielded a product containing approximately 65 wt% benzene and >10 wt% cyclohexyl-compounds. The fresh and spent catalysts were thoroughly characterized by ICP-AES, N2 isothermal adsorption, XRD, XPS and TGA, and the roles of the phosphorus as the catalyst promoter and the effects of MgO as a basic support were also discussed.;In the Part-III of this work, hydrodeoxygenation (HDO) of bio-crude derived from direct liquefaction of birch powder was investigated in supercritical hexane at temperatures of 300-380°C under hydrogen of cold pressure of 2.0-10.0 MPa with MgO-supported sulfided CoMo with phosphorus as the catalyst promoter. The oil products were characterized by GC-MS, elemental analysis and FT-IR, and the fresh and spent catalysts by ICP-AES, N2 isothermal adsorption, XRD, XPS and TGA. The hydro-treatment at temperatures higher than 350°C with the CoMoP/MgO catalyst proved to be effective for de-oxygenating the bio-crude sample, leading to significantly reduced contents of phenolic compounds and carboxylic acids/esters and greatly increased concentrations of oxygen-lean/free compounds such as ketones and hydrocarbons in the hydro-treated oil products. From the elemental analysis results, the upgraded oil products contained higher concentrations of carbon and hydrogen, and much lower concentrations of oxygen and nitrogen, resulting in an increased caloric values. For instance, the treatment at 350°C for 60 min under 5 MPa H2 produced an upgraded oil with 0.2 wt% N, 16.1 wt% 0 and 34 MJ/kg HHV, compared with 0.6 wt% N, 26.2 wt% 0 and 27.1 MJ/kg HHV for the raw bio-crude.;Keywords. Bio-crude; Hydro-liquefaction; Woody biomass; Hydrodeoxygenation; Hydro-treating; Sub-critical methanol; Super-critical methanol; CoMo/MgO; CoMoP/MgO; Sulfided catalysts, Supercritical hexane. |
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