Biomass-derived pyrolysis oil: production emulsification and reaction

  • 林 柏志

Student thesis: Doctoral Thesis

Abstract

The sustainability of fuel resources and environment is an important issue that is of considerable concern in the world currently The development of biofuels is regarded as an effective countermeasure to reduce fossil fuel consumption and CO2 emissions Biomass pyrolysis is widely conducted to produce bio-oil which has regarded as a potential energy carrier to replace conventional fossil fuels The present works in this thesis are based on the biomass pyrolysis route with pathways toward fuels including bio-oil production upgrading and fuel application from the upgraded bio-oil For that the present research is divided into three parts: (1) characterization of biomass pyrolysis; (2) emulsification of bio-oil/ diesel; and (3) oxidative reaction of emulsified fuel The first part is divided into two subsections that examine the pyrolysis behavior of biomass under various conditions In the first subsection the effects of heating modes on sugarcane bagasse pyrolysis were evaluated and the experiments were carried out in a CO2 atmosphere to increase utilization of an abundant CO2 stream In the microwave pyrolysis experiments charcoal is used as the microwave absorber to aid in pyrolysis reactions The results indicate that the yields of pyrolysis products are greatly influenced by the heating modes In the conventional heating the prime product is bio-oil and its yield is in the range of 51-54 wt% whereas biochar is the major product in microwave-assisted heating and its yield ranges from 61 to 84 wt% Two different absorber blending ratios of 0 1 and 0 3 are considered in the microwave pyrolysis The solid yield decreases when the absorber blending ratio decreases from 0 3 to 0 1 while the gas and liquid yields increase Hydrogen is produced under the microwave pyrolysis and its concentration is between 2 and 12 vol% This is attributed to the secondary cracking of vapors and the secondary decomposition of biochar in an environment with microwave irradiation is easier than those with conventional heating In the second subsection the pyrolyses of oil palm fiber (OPF) and oil palm fiber pellet (OPFP) in N2 and CO2 were performed to evaluate the impacts of biomass pattern and carrier gas on the three-phase products Three different reaction temperatures of 400 450 and 500 °C along with 30 min pyrolysis are considered The pyrolysis experiments were carried out in a fixed-bed reactor by slow pyrolysis The results indicate that OPFP pyrolysis gives a higher liquid yield when compared to OPF pyrolysis and the liquid yield using CO2 as a carrier gas is higher than that using N2 The influences of carrier gas and biomass pattern on the components in bio-oils are not profound The higher heating values of OPF and OPFP from pyrolysis are intensified up to 39 and 24 % respectively The CO2 and CO concentration distributions suggest that the most drastic pyrolysis reaction develops at 7-9 min On account of more energy required for breaking methoxyl groups CH4 formation is later than CO and CO2 formations In summary OPFP pyrolyzed in a CO2 environment is a feasible operation for producing bio-oils thereby saving facility space and achieving CO2 utilization The second part of study is focus on emulsification characteristics of bio-oils and diesel at various operating conditions are analyzed Three different commercial emulsifiers (i e Span 80 Tween 80 and Atlox 4914) and four bio-oils obtained by fast pyrolysis of wood wastes from industry are studied When the three emulsifiers are individually employed the performance of the emulsifiers is characterized by the order of Atlox 4914 > Span 80 > Tween 80 An emulsifier with a targeted HLB value of an emulsifier can be obtained by blending Span 80 and Tween 80 or Span 80 and Atlox 4914 The optimum HLB for the emulsification of bio-oils and diesel linearly increases with increasing the atomic O/C or H/C ratio water content or decreasing higher heating value (HHV) of bio-oil The correlation of the optimum HLB and HHV can provide the best resulting mix which can be employed for practical emulsification operation between bio-oils and diesel The functional groups in the emulsifiers bio-oils and diesel are analyzed by Fourier transform infrared spectroscopy (FTIR) to characterize the emulsion In the third part of study the reaction interaction during oxidation of a number of bio-oil/diesel emulsified fuels at various bio-oil contents and bio-oil-to-emulsifier weight ratios (i e B/E ratios) are examined to provide a basis for the applications of pyrolysis bio-oil The bio-oil used in this part of study is obtained by the fast pyrolysis of rubber wood from industry The commercial Atlox 4914 is used as the surfactant in the emulsification while a thermogravimetric analyzer is employed in the analysis A significant synergistic effect is observed during the oxidation of the emulsified fuels where the interaction can be partitioned into an antagonistic zone (? 210 °C) and a synergistic zone (? 210 °C) The maximum interaction occurs at about 380 °C and the synergistic zone enhances the oxidation of the fuels A dimensionless parameter termed the synergistic index (SI) is introduced to measure the interaction degree
Date of Award2019
Original languageEnglish
SupervisorWei-Hsin Chen (Supervisor)

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