Study On Refining And Upgrading Of Biomass Pyrolysis Oil

Biomass pyrolysis oil is a kind of renewable liquid fuel originated from biomass. However, the bio-oil is acidic, viscous, reactive and thermally unstable black liquid. Due to its special properties, many problems arise in its handling and utilization. For possible future use as replacements for hydrocarbon chemical feedstocks and fuels, the oils will require considerable upgrading to improve its fuel characteristics. Currently, most used upgrading techniques are hydrodeoxygenation and catalytic cracking of pyrolysis vapors. However, the yield of upgraded oils is generally low because of the high yields of char, coke and tar. In this work, in order to avoid the problems in hydrodeoxygenation and catalytic cracking of bio-oil, we aim to find another method that would utilization of pyrolysis oils under mild conditions, the obtained results were as followed.1. The water content of bio-oil used in this research was 33.0%. The pH value was 2.82. The dynamic viscosity was18.5 mm²/s, and gross calorific value was 14.3 kJ g^-1. The average molecular weight was 2042. After 3 months storage, phrase separation was occered.2. The mesoporous molecular sieve MCM-41 possesses a hexagonal arrangement of uniformly sized unidimensional mesoporous with diameters 2.7 nm, larger surface area of more than 577 m²/g, and should therefore be a potential catalyst for the reactions concerned with larger molecule reactants. However, the acidity of MCM-41 is weak and is of low catalytic activity for the reaction using strong acid catalysts. Therefore, enhancing the acidity of MCM-41 is the key to using it as catalysts for the reactions.3. S₂O₈^2-/ZrO₂-MCM-41 was used as solid acid catalyst in upgrading bio-oil through reactive rectification. The suitable reaction conditions were obtained as follows:catalyst: bio-oil 4% (mass part), reflux ratio 1 : 6, bio-oil : ethanol : hydrogen peroxide(aqueous solution 30%) = 1 : 0.5 : 0.4 (mass ratio). Under above conditions, yield of light oil was about 21.0%(account to original bio-oil). GC and FT-IR analysis showed that light oil contain various ester compounds and the heavy oil was nonviolated compounds in original bio-oil. 4. The waste water from reactive rectification was treated using ethyl acetate as extraction solvent. It was found out that about 38.1% organic compounds were separated by extraction. We also use active carbon as adsorbent after extraction process. It was determined that 68% organic compounds were separated in total. The separated organic compounds was characterized by GC-MS.5. Fast curing novolaks was prepared using HCl and zinc acetate as catalyst through two step manner.cure time of novolaks were range from 30 to 40 s and softening point range from 80℃to 90℃. The structure of novolaks was characterized by DSC and FT-IR.Thermal stability of the resin was characterized by TG.6. The possibility of using water insoluble fraction from biomass pyrolysis oil as partial substitute of phenol in synthesis of phenolic novolac under the catalyst of HCl / Zn(AC)₂ has been proved using differential scanning calorimetry(DSC) and fourier transformed infrared spectroscopy(FT-IR). Synthesis of novolac resins with different concentration (10, 20, 30 and 40 wt%) of water insoluble fraction were performed. Curing reaction of synthesized resins with hexamethylenetetramine indicated that in order to obtain cure time of novolak range from 40 to 50 s and softening point range from 85℃to 95℃, the concentration of water insoluble fraction as partial substitute of phenol was below 10%. The structure of novolak was characterized by FT-IR.This study provides an alternative method and guidance for solid acid catalyst to be used in bio-oil upgrading. Moreover, these upgrading methods were particularly useful in materials science.