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Please use this identifier to cite or link to this item: http://hdl.handle.net/10087/8124

Title: Bio-oil Production from Rice Husk through Catalytic Hydropyrolysis in Fluidized Bed Reactor
Other Titles: 流動床での触媒水素化熱分解による籾殻からのバイオオイル製造
Authors: Sirimirin, Meesuk
シリミリン, ミース
Keywords: Bio-oil
Hydropyrolysis
Rice husk
Deoxygenation
Hydrooxygenation
Ni/LY char
Issue Date: Feb-2012
Publisher: 群馬大学工学部
Abstract: Bio-oil from biomass through thermochemical conversion is not readily usable as fuel because of its extremely high oxygen content and relatively poor storage stability. Thus, fast pyrolysis to upgrade the quality of biomass is possible by means of thermochemical pathway through which pyrolysis oil is upgraded via hydroprocessing to motor-vehicle grade oil product. The catalytic treament of biomass under hydrogen pressure (i.e., hydropyrolysis) is an attractive route to obtainin high yield of liquid hydrocarbons, such as benzene, toluene, and xylene (BTX). The effect of catalyst is to convert oxygen in bio-oil to H2O, CO, and CO2. The decrease in oxygen content contributes to a remarkable increase in the heating value of bio-oil. We have proposed in our research the utilization of nickel-loaded brown coal (Ni/LY) char as an alternative catalyst for upgrading the quality of bio-oil product. The Ni/LY char was prepared according to the ion-exchange method as it is inexpesive and there are reports that the metallic Ni disperses well on the support in Ni/LY char with large specific surface area. Loy Yang brown coal was used in the preparation of the catalyst because it contains carboxyl and phenol groups which can exchange ions with metals. In this study the effects of catalysts (Ni/Al2O3, Ni/LY char, Dolomite, and CoMo/Al2O3) on product yield and composition of bio-oil were investigated. Then the catalytic behavior of Ni/LY char was examined and employed to obtain the bio-oil with relatively low oxygen content that can be used as liquid fuel and chemical feedstock. In chapter 2, pyrolysis of rice husk was carried out in fluidized bed reactor. The effect of different catalysts (i.e., Ni/Al2O3, Ni/LY char, Dolomite and CoMo/Al2O3) was investigated. The results showed that a low molecular weight and low oxygen content of bio-oil are obtained with pyrolysis using catalyst. Catalysts supported the deoxygenation reaction by convert the oxygenated compounds of bio-oil to form H2O, CO2 and CO. Best results are obtained with Ni/LY char and CoMo/Al2O3 which can reduce the oxygen content of bio-oil from 33.8% without catalyst to 27.6 and 24.9% with Ni/LY char and CoMo/Al2O3, respectively. The decreasing of the oxygen content of bio-oil contributes to a remarkable increase in HHV. However, Ni/LY char is deemed more favorable than CoMo/Al2O3 in term of the production cost of bio-oil. In chapter 3, hydropyrolysis of rice husk without catalyst was performed in a fluidized bed reactor. The effects of parameter conditions (i.e., hydrogen pressure, temperature, gas residence time (GRT), and gas hourly space velocity (GHSV)) on product yields were studied to determine the optimal condition for bio-oil yield. The hydropyrolysis under 0.1 MPa hydrogen gas produced bio-oil with relatively low oxygen content. The optimal hydropyrolysis temperature for the production of bio-oil from rice husk was found to be 500 °C and GRT of 2.7 s. The high GHSV of 4891 h-1 was found to be more favorable for the production of bio-oil due to the reduced residence time of vapors in bed material, maximizing the bio-oil yield at about 47.1 wt.%. In chapter 4, hydropyrolysis of biomass materials (i.e., rice husk, coconut shell, and pine) was conducted in a fluidized bed reactor to evaluate bio-oil production. The hydropyrolysis was performed at 500 °C, GRT of 2.7 s and GHSV of 4891 h-1. The bio-oil yields from rice husk, pine, and coconut shell were 47.1, 64.5, and 52.1 wt.%, respectively. The bio-oils were analyzed with an elemental analyzer, Karl-Fischer moisture titration, Fourier transform infrared (FTIR) spectroscopy, and gas chromatography/mass spectrometry (GC/MS). The results showed that the bio-oils from all biomass have high oxygen content and oxygenated compounds such as phenols. The HHVs of bio-oils from pine and coconut shell are higher than that of rice husk due to their high carbon content, while rice husk has the lowest HHV, which can be ascribed to its low carbon content and high oxygen content. It is advisable that the bio-oil products be further processed to remove the condensed water and oxygen content for chemical and/or biofuel production. In chapter 5, hydropyrolysis of rice husk was carried out in a fluidized bed reactor at atmospheric pressure. The effects of different catalysts, on the carbon conversion of rice husk and composition of bio-oils were studied. The experiments with catalysts under hydrogen atmosphere to produce bio-oils with much lower oxygen content were performed. The results show that the oxygen content of bio-oils is markedly reduced because the oxygenated hydrocarbons are hydrocracked resulting in the formation of H2O, CO and CO2 when catalysts are introduced. The oxygen content of bio-oil under hydrogen atmosphere decreased from over 31.1% without catalyst to 25.9%, 20.5%, 26.5% and 10.1% with Ni/Al2O3, Ni/LY char, Dolomite and CoMo/Al2O3, respectively. The use of CoMo/Al2O3 and Ni/LY char under hydrogen atmosphere showed high activity to decrease the oxygen content, which leaded to a higher heating value and more aromatic hydrocarbons. These experiments indicated that catalytic hydropyrolysis is suitable for producing bio-oils with lower molecular weight and high aromatic hydrocarbons which are possible to use as a potential liquid fuel and chemical feedstock. In chapter 6, catalytic hydropyrolysis of rice husk using Ni/LY char was carried out in a fluidized bed reactor in order to determine the bio-oil with the lowest oxygen content and investigate the effects of an inexpensive Ni/LY char activity, catalytic hydropyrolysis temperature, and volume fraction of Ni/LY char on product yield and composition of bio-oils. These conditions were tested at the optimal condition (i.e., temperature of 500 °C, GRT of 2.7 s and GHSV of 4891 h-1). In the presence of Ni/LY char the oxygen content of bio-oil decreased by about 16% compared with that of non-catalyst. Raising the temperature from 500 to 650 ºC reduced the oxygen content of bio-oil from 27.5% to 21.5%. The characteristics of bio-oil were analyzed by Karl Fischer, GC/MS, GPC, FT-IR, and CHN elemental analysis. The result indicated that hydropyrolysis of rice husk using Ni/LY char at temperature of 650 ºC produced bio-oil with relatively lower oxygen content, oxygenated compounds, high aromatic hydrocarbons, and high heating value. For the effect of volume fraction of Ni/LY char, which was investigated at the optimal condition for bio-oil yield, it was found that the oxygen content of bio-oils decreased, whereas the higher heating value of bio-oils increased when increasing the volume fraction of Ni/LY char. The bio-oil with the lowest oxygen content (20.7 wt.%) and the highest heating value (30 MJ/kg) was obtained with 75% volume fraction of the Ni/LY char. The catalytic hydropyrolysis oil contained more aromatic hydrocarbons with slightly reduced oxygenated compounds than that from the non-catalytic hydropyrolysis oil. High quantities of aliphatic and aromatic hydrocarbons were obtained from hydropyrolysis with volume fraction of Ni/LY char > 50%. The results indicated that the bio-oils from the hydropyrolysis, using high volume fraction of Ni/LY char (75 v/v%) at high catalytic hydropyrolysis temperature of 650 °C, contained more aromatic hydrocarbons with slightly reduced oxygenated compounds and could be used as liquid fuel and chemical feedstock.
Description: 学位記番号:工博甲442, 学位の種類:博士(工学)
URI: http://hdl.handle.net/10087/8124
Academic Degrees and number: 12301A000442
Degree name: 博士(工学)
Degree-granting institutions: 群馬大学
Appears in Collections:学位論文

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