Lignocellulosic biomass pyrolysis and hydrodeoxygenation of bio-oil using transition metals (Ni, Co, Fe) based catalysts = 전이금속(Ni, Co, Fe) 기반 촉매를 이용한 바이오 오일의 목질계 바이오매스 열분해 및 수소화탈산소화|RISS 상세보기

다국어 초록 (Multilingual Abstract)

Biomass is a promising renewable resource to generate energy owing to its abundance and low cost. Lignocellulosic biomass is known as a strong candidate due to their advantages compare to other biomass, e.g. high energy, but low costs, low ash content, and very low nitrogen and sulfur contents. Lignocellulosic biomass is consisted of hemicellulose, cellulose, and lignin. Among several thermal conversion technologies, pyrolysis is a feasible approach to convert biomass into energy and chemicals due to reasonable coast and simple operation.
To understand the pyrolysis kinetic of lignocellulosic biomass, the main components of lignocellulosic biomass such as cellulose and lignin were used to investigate systematically using thermal gravimetric analysis (TGA) and micro-tubing reactor. The simulated data of α-cellulose is in good agreement with the experimental data in the aspects of the conversion and the conversion rate versus temperature. The decomposition of α-cellulose, mainly occurring at 270–420℃, induced an apparent activation energy ranging from 175.42 kJ/mol to 197.73 kJ/mol at a conversion of 10–90%. With 0.1–0.2 wt% K or Ca impregnation into the α-cellulose, the mean activation energy for pyrolysis was lowered (from 181.47 kJ/mol (for α-cellulose) to 141.11 kJ/mol (for 0.2 wt% K/α-cellulose) and 159.46 kJ/mol (for 0.1 wt% Ca/α-cellulose)) and higher amounts of liquid and gas products were produced. Furthermore, the addition of potassium and calcium increased the production of lower molecular weight components, such as furfural and its derivatives. The kinetic rate constants indicate that the predominant reaction pathway is from α-cellulose into a liquid product, rather than from α-cellulose into a gas product. The pyrolysis characteristics and kinetics of Organosolv lignin from pine trees were also investigated. Through these approaches, the activation energy of Organosolv lignin pyrolysis was calculated. The activation energy by the Friedman method ranged from 70.11–355.92 kJ/mol, while relatively lower values (48.51–302.47 kJ/mol) were calculated by the peak separation method. Thermodynamic parameters such as entropy (ΔSo), Gibbs free energy (ΔGo), and enthalpy (ΔHo) were also calculated to understand the reaction pathways from a thermodynamic perspective. Based on the pyrolysis mechanisms proposed in this study, the reaction rate constants of different steps were determined. The primary reaction route was identified to be the pyrolysis of Organosolv lignin to liquid products such as bio-oils. Finally, the compositions of gaseous and liquid products formed by pyrolysis were analyzed using the micro-tubing reactor. The Organosolv lignin was polymerized into lower molecular weight structures by the pyrolysis process. CO, CO2, and CH4 were mainly produced as gaseous products, while Organosolv lignin was primarily decomposed into guaiacol, 3-methoxy-1,2-benzendiol, vanillin, vanillic acid, acetovanillate, and syringaldehyde.
Pine trees is considered as promising candidate biomass sources compare to other lignocellulosic biomasses for the production of high liquid yield bio-oil. Pyrolysis of pitch pine has been investigated in a bubbling fluidized bed reactor. In this system, silica sand and nitrogen were used as the fluidizing bed material and fluidizing medium, respectively. The experimental was systemically perform on different temperature, fluidized velocity, and particle size of biomass. The optimum temperature condition at which the bio-oil yields reached the highest value (65.5%) was 500 ℃. In addition, the higher heating values of bio-oils from pitch pine biomass were reached in the range 22 MJ/kg to 24 MJ/kg. Moreover, this bio-oil had high content of useful chemicals including such as levoglucosan, furfural, and guaiacol. The large amount of C5–C11 (gasoline fraction) produced make the pyrolyzed oil originating from pitch pine trees a promising biofuel candidate.
Since guaiacol is a key compound obtained from lignocellulosic biomass pyrolysis bio-oil, it is often utilized as a model compound in most studies. Additionally, it contains methoxy (-OCH3) and hydroxy (-OH) groups, which are important in ascertaining its value as a fuel source. Spherical -Al2O3-SiO2 catalysts with varying Al/Si ratios were prepared by combining the sol-gel and spray pyrolysis (SP) methods to examine in hydrodeoxygenation process. The effectiveness of the product catalysts was then tested via the hydrodeoxygenation (HDO) of guaiacol, a model compound of bio-oil obtained from the pyrolysis of lignocellulosic biomass. Our results showed that the -Al2O3-SiO2 catalyst with a 50:50 Al/Si ratio after calcination at 450 C exhibited the highest guaiacol conversion (81.79%) at a reaction temperature of 300 C, atmospheric pressure, and a weight hourly space velocity (WHSV) of 6.5 h-1. During guaiacol HDO, the carbon–oxygen cleavage and methyl group transfer reactions occurred on the -Al2O3-SiO2 catalyst, which converted the guaiacol into the respective deoxygenated products, including 2,6-xylenol, 2,3,5,6-tetramethyl phenol, pentamethyl benzene, and hexamethyl benzene. In addition, Ni/γ-Al2O3 and Fe/activated carbon (AC) catalysts were prepared by an incipient impregnation method and then also utilized for hydrodeoxygenation (HDO) of guaiacol (GUA). The AC used in the process was derived from bamboo through steam activation. At 300 °C and atmospheric pressure, 91.52% of GUA was successfully transformed into cresol and 1,2-dimethoxybenzene in liquid phase using 10 wt% of the Fe/AC catalyst, which was calcined at 550 ℃. Under the same reaction conditions, utilizing 10 wt% of the Ni/γ-Al2O3 catalyst, which was calcined at 450 ℃, resulted in 96.88% GUA conversion, producing 13.03% of cresol, 58.98% of 1,2-dimethoxybenzene, and 27.99% of 3-methyl guaiacol. The reaction pathways for the conversion of guaiacol HDO were also proposed in this study.
The catalytic hydrodeoxygenation (HDO) processes for upgrading pyrolysis bio-oils from wood pallet sawdust (WPS) were studied using activated carbon (AC) as a support of mono- (Co/AC and Fe/AC) and bi-metallic (Co-Fe/AC) catalysts. At 350 ℃ and 60 bar, 20 wt% Co/AC showed the highest liquid yield (70.46 wt%) along with HHV of 34.22 MJ/Kg. Among the tested bimetallic catalysts, comparable liquid yield (68.85 wt%) and HHV (34.16 MJ/kg) were achieved with 20 wt% 4Co-1Fe/AC catalyst. Methyl phenol derivatives were found to be the main component in upgraded bio-oil. The carbon number of upgraded bio-oil was mainly distributed in C5–C11 fraction, especially with the C8 component (20.40 wt%). The catalysts were deactivated by the formation of carbonaceous compounds on the external surface, oxidation of metal species, and blocking of active sites on catalysts.

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목차 (Table of Contents)

Abstract………………………………………………………………………………………...i
List of Tables…………………………………………………………………………….……vi
List of Figures……………………………………………………………………………...…ix
List of Abbreviation………………………...……………………………...……………...…xii
CHAPTER 1 – General Introduction

Abstract………………………………………………………………………………………...i
List of Tables…………………………………………………………………………….……vi
List of Figures……………………………………………………………………………...…ix
List of Abbreviation………………………...……………………………...……………...…xii
CHAPTER 1 – General Introduction
1.1 Background…………………………………………………………………………..……1
1.2 Motivation…………………………………………………………………………………2
1.3 Research objective…………………………………………………………………………4
1.4 Dissertation Overview……………………………………………………………………..5
1.5 References…………………………………………………………………….…………...8
CHAPTER 2 – Literature Review
2.1 Concept of biomass……………………………………………………………..………..11
2.1.1 Biomass definition………………………………...…………………………….…11
2.1.2 Biomass resource and classification……………………………...………………..11
2.1.3 Lignocellulosic biomass…………………………………………..……………….12
2.1.3.1 Hemicellulose & Cellulose………………………………..……………....12
2.1.3.3 Lignin………………………………………………………………..…….13
2.1.4 Chemical composition of lignocellulosic biomass…………………………..…….14
2.1.5 Biomass application and approaches of biomass conversion into energy………....15
2.2 Pyrolysis………………………………………………………………………………….16
2.2.1 Definition…………………………………………………………………..……...16
2.2.2 Classification………………………………………………………………..……..16
2.2.3 Pyrolysis mechanism and pathways………………………………………….....…18
2.2.4 Fast pyrolysis oil……………………………………………………………..……19
2.3 Catalytic upgrading pyrolysis oil………………………………………………………...20
2.3.1 Hydrodeoxygenation………………………………………………………………20
2.3.1.1 HDO of model compound…………………………………………..…….20
2.3.1.2 Catalyst for HDO……………………………………………………..…...20
2.3.1.3 HDO upgrading bio-oils…………………………………………..………21
2.4 References………………………………………………………………………………..23
CHAPTER 3 - Pyrolysis Kinetics and Product Distribution of α-Cellulose and Organosolv Lignin in microtubing reactor
3.1 Introduction………………………………………………………………………………28
3.2 Methodology……………………………………………………………………………..31
3.2.1 Materials………………………………………………………………...…………31
3.2.2 Thermogravimetric analysis………………………….……………..………….….32
3.2.3 Kinetic analysis………………………………………………………………...….33
3.2.4 Pyrolysis of α-cellulose and Organosolv lignin in a micro-tubing reactor……..…35
3.3 Result and discussion
3.3.1 Pyrolysis kinetic of α-cellulose, effect of AEAM metal on kinetic mechanism and product distribution using TGA and micro-tubing reactor…………………….….……..36
3.3.2 Pyrolysis kinetic of Organosolv lignin and product distribution using TGA and micro-tubing reactor……………………………………………………..…….……...…54
3.4 Summary…………………………………………………………………………....……71
3.5 References………………………………………………………………………....……..73
CHAPTER 4 - Fast pyrolysis of pitch pine biomass in a bubbling fluidized-bed reactor for bio-oil production
4.1 Introduction…………………………………………………….…………………...……80
4.2 Methodology………………………………………………………………...……...……82
4.2.1 Feedstock biomass…………………………………………………..…….....……82
4.2.2 Experimental apparatus……………………………………………..……….….…82
4.2.3 Product analysis……...……………………………………………..….........…..…84
4.3 Result and discussion………………………………………………………………….…85
4.3.1 Biomass sample characterization……………………………………………….…85
4.3.2 Thermogravimetric analysis of pitch pine tree samples…..……………………….88
4.3.3 Effect of pyrolysis conditions on product distribution…..……………..........…….91
4.3.4 Compositions of gas product…..…………………………………………………..97
4.3.5 Analysis of bio-oil…..…………………………………………………...………...98
4.4 Summary………………………………………………………………….…….........…105
4.5 References…………………………………………………………………….…...……106
CHAPTER 5 – Hydrodeoxygenation of a bio-oil model compound derived from woody biomass using various catalysts
5.1 Introduction……………………………………………………………………..........…109
5.2 Methodology………………………………………………………………………….…111
5.2.1 Preparation of catalyst……………………………………………………...…….112
5.2.1.1 Preparation of γ-Al2O3-SiO2 catalyst…………………….…..………..…112
5.2.1.2 Preparation of Ni/γ-Al2O3 and Fe/AC catalyst………..….…………...…113
5.2.2 Characterization methods…………………….……………………………..……113
5.2.2.1 Characterization of γ-Al2O3-SiO2 catalyst………………….............……112
5.2.2.2 Characterization of Ni/γ-Al2O3 and Fe/AC catalyst...…….………..……114
5.2.3 Guaiacol hydrodeoxygenation and product analysis……………………….....…115
5.3 Result and discussion…………………….…………………………………………..…117
5.3.1 Characteristics and application of γ-Al2O3-SiO2 catalyst on HDO of guaiacol………………………………………………………………………,,…..…...117
5.3.2 Characteristics and application of Ni/γ-Al2O3 and Fe/AC catalysts on HDO of guaiacol……………………………………………...………..…………….……..…...136
5.4 Summary....………………………………………………………..…………….……...152
5.5 References…..………………………………………………………..……………...….153
CHAPTER 6 - Hydrodeoxygenation of Wood Pallet Sawdust Pyrolysis Oil Using Activated Carbon Supported Cobalt and Iron Catalysts
6.1 Introduction…………………………………………….………….………..…………..161
6.2 Methodology……………………………………….…………….…………..…………163
6.2.1 Materials…………………………………………………..…...…………...….…163
6.2.2 Preparation of catalyst……………………………………………................……163
6.2.3 Characterization methods……………………………………………...……...….164
6.2.4 Bio-oil hydrodeoxygenation and product analysis……………………..……...…165
6.3 Result and discussion………………………………………………..………..…...……166
6.3.1 Characterization of biomass and bio-oil………………….…..…………..…...…166
6.3.2 Catalyst characterization………………….…..………….................................…167
6.3.3 Effect of reaction conditions on product distribution………………….…………176
6.3.4 Effect of metal loading and bimetallic catalyst on product distribution…………182
6.3.5 Catalyst deactivation………………….…..……………………………….......…194
6.4 Summary…………………….…..…………………………………………………...…197
6.5 References………………….…..………………………………………………….....…198
CHAPTER 7 – Conclusion and further researches………………………………….…..204
7.1 Conclusions……………………………………………………………………………..204
7.2 Further researches……………………………………………………………………….207
APPENDIX…………………………………………………………………………………209
ACKNOWLEDGMENTS………………….………………………………..…………...…222

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