Biomass conversion and catalytic hydrodeoxygenation of bio oil model compound doctor of philosophy major chemical engineering

Lignocellulosic biomass has been studied extensively in terms of their pyrolysis characteristics as well as bio-oil yield and bio-oil compositions.. The obtained results indicated that t

Dissertation for the Degree of Doctor of Philosophy

Biomass Conversion and Catalytic Hydrodeoxygenation of Bio-oil Model Compound

VO THE KY

Department of Chemical Engineering

Graduate School Kyung Hee University Seoul, Korea

August, 2018

Biomass Conversion and Catalytic Hydrodeoxygenation of Bio-oil Model Compound

VO THE KY

Department of Chemical Engineering

Graduate School Kyung Hee University Seoul, Korea

August, 2018

Biomass Conversion and Catalytic Hydrodeoxygenation of Bio-oil Model Compound

by

VO THE KY

Supervised by

Prof Jinsoo Kim

Submitted to the Department of Chemical Engineering and the Faculty of the Graduate School of Kyung Hee University in partial fulfillment

of the requirement for degree of Doctor of Philosophy

Dissertation Committee:

Chairman Prof Eun Yeol Lee………

Prof Jinsoo Kim………

Prof Seung-Soo Kim………

Prof Jae-Heung Ko………

Prof Bum Jun Park………

Lignocellulosic biomass has been studied extensively in terms of their pyrolysis characteristics as well as bio-oil yield and bio-oil compositions Most of these biomass were used as wild – type biomass Recently, transgenic biomass could be considered a promising biomass for production of bio-oil and valuable chemicals when its gene structure was modified from that of the wild-type to change the biochemical components (lignin, hemicellulose, cellulose) Hybrid poplar trees, which are valuable biomass feedstocks because they can grow very fast and are good candidates for genetic improvement with regard to bioenergy feedstock production A comparative study on pyrolysis characteristics and kinetic of the wild –type and genetically engineered hybrid poplar trees were conducted systematically to understand their thermal decomposition behaviors that were

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necessary before using these feedstocks The obtained results indicated that transgenic biomass had lower activation energy and produced higher bio-oil yield compared to that of wild type under the same pyrolysis conditions In addition to this, chemical compositions

of biocrude produced from genetic modified hybrid poplars had higher derivatives but lower lignin-derivatives compared to those obtained from wild –type biomass

carbohydrate-Heterotrophic microalgae Aurantiochytrium sp is a promising feedstock for biofuel production due to its fast growth rates and high lipid content (50 wt % of dry biomass) Another kid of microalgae strain, Tetraselmis sp was cultivated successfully by artificial seawater semi-permeable membrane photobioreactor promising to provide an economic and sustainable biofuel production from microalgae Pyrolysis characteristics and kinetics of microalgae by means of thermogravimetric analysis (TGA) and pyrolysis on a micro-tubing reactor The thermal decomposition behaviors of biochemical compositions (carbohydrates, proteins, lipids) of microalgae were investigated and compared Free-model methods such as Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) were applied to estimate activation energy for pyrolysis of algal biomass These methods have widely used for the determination of activation energy since they can be used without knowledge of the reaction model A lumped kinetic model was applied for the expertiment data The obtained results indicated that the predominant pyrolysis reaction pathway of Aurantiochytrium sp was from biomass to bio-oil rather than from biomass to gas, indicating that the feasibility of converting this macroalgae biomass into bio-oil by fast pyrolysis

Hydrothermal liquefaction of microalgae (Aurantiochytrium sp and Tetraselmis sp.) was conducted at different temperature (250 ~ 400 oC) and time (10~ 90 min) Under these conditions, the biochemical compositions in microalgae cells were decomposed to produce biocrude, gas, aqueous- phase product and biochar Biocrude with chemical compositions depend on the biomass feedstock as well as experimental conditions A reaction network that can generally describe the hydrothermal liquefaction of each carbohydrates, proteins and lipids in the biomass cell Besides, there exists interconversion between product phases as bio-oil and aqueous –phase, heavy –oil and light -oil were also included in the reaction network The results showed that microalgae were rapidly

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decomposed for first few minutes of reaction time With longer reaction time, the interconversion between products phases were predominant reactions Based on this reaction network, quantitative kinetic model for HTL of microalgae, which can be useful for design, control and optimization of HTL processes, was proposed The estimated reaction rates and activation energy suggested the dominant reaction pathways as well as the distribution of the biochemical compositions to the bio-oil phase Kinetic parameters were used to explore the parameter space in order to predict product yields as a function of reaction time and temperature

Bio-oil obtained from pyrolysis and hydrothermal liquefaction of microalgae cannot be used directly since it is high viscosity, high acidity, and low heating value due to the presence of significant quantities of many oxygen-contain compounds such as acids, aldehydes, ketones and phenolic compounds Therefore, upgrading the quality of biomass –derived biocrude have attracted much attention for recent years Hydrodeoxygenation (HDO) reaction is one of the most potentially valuable processing routes to selectively cleave C – O and C – C bonds in oxygen-containing substances In this work, a novel method combining sol-gel and spray pyrolysis was applied to synthesize Mo/Al2O3 –TiO2

catalysts for upgrading of hexadecanoic acid (palmitic acid) that was found to be a major component (ca 50%) in the biocrude obtained from pyrolysis and HTL of microalgae Aurantiochytrium sp During spray pyrolysis process, the spherical composite particles were formed directly from the droplets containing a well-dispersed mixture of molybdenum salt, boehmite sol and titania sol through one-step pyrolysis The results obtained from catalytic activity studies on hydrodeoxygenation of palmitic acid showed that the Mo/Al2O3-TiO2 catalysts exhibited excellent catalytic performance as high HDO conversion (100%) and high saturated hydrocarbon selectivity (93.18%) These results were much better than those of catalyst derived from conventional impregnation method Effects of TiO2 concentration used to modify γ-Al2O3 on the catalytic activity was systematically investigated Reusability experiment results showed that there were a slight decrease in metal/metal oxides concentration ratio of reduced catalyst after four time uses

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Table of contents

Abstract i

List of Tables viii

List of Figures ix

CHAPTER 1 - General Introduction 1.1 Background 1

1.2 Motivation 5

1.3 Research objectives 7

1.4 Dissertation overview 8

1.5 References 11

CHAPTER 2 - Literature Review 2.1 Biomass concepts 16

2.1.1 Biomass 16

2.1.2 Biomass resources 16

2.1.3 Genetically engineered biomass 17

2.1.4 Microalgae 17

2.1.4.1 Microalgal Aurantiochytrium sp 17

2.1.4.2 Tetraselmis sp 18

2.1.5 Chemical compositions of microalgae 18

2.1.6 Biomass applications 20

2.1.7 Biomass into energy 20

2.2 Pyrolysis 23

2.2.1 Definition 23

2.2.2 Classification 23

2.2.3 Pyrolysis of biomass compositions 24

2.2.4 Kinetic models for pyrolysis of biomass 25

2.3 Hydrothermal liquefaction 26

2.3.1 Definition 26

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2.3.2 Reaction networks of HTL of microalgae 27

2.4 Hydrodeoxygenation (HDO) of bio-oil 29

2.5 References 32

CHAPTER 3 - Pyrolysis Characteristics and Kinetics of Wild-Type and Genetically Engineered Hybrid Poplar Trees 3.1 Introduction 42

3.2 Experimental 44

3.2.1 Hybrid poplars and growth conditions 44

3.2.2 Characterizations of hybrid poplars 44

3.2.3 Pyrolysis of hybrid poplars in a micro-tubing reactor 45

3.3 Results and discussion 46

3.3.1 Material characterizations 46

3.3.2 Thermogravimetric analyses (TGA) 50

3.3.3 Pyrolysis kinetics of hybrid poplars 54

3.3.4 Pyrolysis product distributions and bio-oil analysis 59

3.3.5 Kinetic model for pyrolysis of hybrid poplars 65

3.3.6 Kinetic parameters analyses 69

3.3.7 Model predictions of pyrolytic products 71

3.4 Conclusions 73

3.5 References 74

CHAPTER 4 - Pyrolysis Characteristics and Kinetics Studies of Microalgae by Non-isothermal and Isothermal Decompositions 4.1 Introduction 79

4.2 Materials and methods 81

4.2.1 Materials 81

4.2.2 TGA analysis 82

4.2.3 Pyrolysis in a micro-tubing reactor 82

4.2.4 Product analysis 83

4.3 Results and discussion 84

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4.3.1 Material characterizations 84

4.3.2 TGA analyses of microalgae samples 88

4.3.3 Kinetic parameters of the pyrolysis of Aurantiochytrium sp KRS 92

4.3.4 Pyrolysis product distribution and bio-oil analyses 96

4.3.5 Kinetic model for pyrolysis of Aurantiochytrium sp KRS 100

4.4 Conclusions 105

4.5 References 106

CHAPTER 5- Hydrothermal Liquefaction of Microalgae 5.1 Introduction 110

5.2 Experimental 111

5.2.1 Methods and materials 111

5.2.1.1 Microalgae cultivation 111

5.2.1.2 Determination of the cellular compositions 112

5.2.2 Hydrothermal liquefaction 112

5.3 Results and discussion 116

5.3.1 Material characterizations 116

5.3.1.1 Biochemical compositions 116

5.3.1.2 FT-IR analyses 116

5.3.2 HTL product distributions and analyses 121

5.3.2.1 HTL of microalgae Aurantiochytrium sp 121

5.3.2.2 HTL of microalgae Tetraselmis sp 126

5.3.3 Kinetic models for HTL of microalgae 137

5.3.3.1 Kinetic models for HTL of Autrantiochytrium sp 137

a Reaction network and kinetic model 137

b Kinetic parameter analyses 141

c Model predictions of the liquefaction product distributions 144

5.3.3.2 Kinetic models for HTL of Tetralselmis sp 146

a Reaction network and kinetic model 146

b Kinetic parameter analyses 150

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c Model predictions of the liquefaction product distributions 154

5.4 Conclusions 156

5.5 References 157

CHAPTER 6 - Catalytic Hydrodeoxygenation of Microalgae –derived Bio-oil Model Compound 6.1 Introduction 162

6.2 Experimental 165

6.2.1 Synthesis of catalysts 165

6.2.2 Catalyst preparation 168

6.2.3 HDO of Palmitic acid and product analyses 169

6.3 Results and discussion 170

6.3.1 Textural properties 170

6.3.2 Morphologies analyses (SEM) 175

6.3.3 X-ray Diffraction studies (XRD) 178

6.3.4 FT-IR analyses 180

6.3.5 XPS analyses 182

6.3.6 H2 – TPR analyses 187

6.3.7 NH3 –TPD analyses 189

6.4 Hydrodeoxygenation of Palmitic acid 192

6.4.1 HDO with varied catalysts 192

6.4.2 Effects of reaction temperature 195

6.4.3 Catalyst stability studies 197

6.5 Conclusions 200

6.6 References 201

CHAPTER 7 - Conclusions and Further Researches 7.1 Conclusions 208

7.2 Further researches 210

ACKNOWLEGEMENTS 212

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List of Tables

Table 2.1 Chemical compositions of algae 19

Table 3.1 Approximate and ultimate analyses of WT and TP 49

Table 3.2 Activation energy of WT and TP obtained by KAS and FWO methods 57

Table 3 3 Product yield distribution from pyrolysis of WT and TP samples 60

Table 3.4 Composition of bio-oils obtained from pyrolysis of WT and TP samples 61

Table 3.5 Optimized values of the rate constants and activation energy 70

Table 4.1 Characteristics of the Auranitochytrium sp KRS 101 86

Table 4.2 Metal and phosphorous contents of Auranitochytrium sp KRS 101 87

Table 4.3 Activation energies obtained by KAS method for various conversions… 95

Table 4.4 Product yield distributions from pyrolysis of Auranitochytrium sp KRS 98

Table 4.5 Composition of the bio-oil obtained from pyrolysis of Auranitochytrium sp KRS 101 at 380 oC for 1.5min 99

Table 4.6 Reaction rate constants and activation energies 104

Table 5.1 Biochemical compositions of various microalgae .118

Table 5.2 Major FT-IR adoption bands of microalgae 120

Table 5.3 Product yield distribution from HTL of Aurantiochytrium sp 123

Table 5.4 Composition of bio-oil obtained from HTL of Aurantiochytrium sp 124

Table 5.5 Product yield distribution from HTL of Tetraselmis sp 128

Table 5.6 Compositions of the HO and LO fractions obtained from the HTL of Tetraselmis sp (350 oC, 10min) 129

Table 5.7 Optimized values of the rate constants and activation energy at each temperature 142

Table 5.8 Optimized values of the rate constants and activation energies at each temperature 153

Table 6.1 Textual properties of SP-derived supports and Mo/Al2O3 –TiO2 catalysts 174

Table 6.2 Electron binding energies (Eb) for SP-derived supports and Mo/Al2O3 – TiO2 catalysts 184

Table 6.3 Acid sites distribution in calcined SP- derived catalysts 191

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List of Figures

Figure 2.1 Energy products and classification 22

Figure 2.2 The global and secondary kinetic model of thermal decomposition of biomass 26

Figure 2.3 Hydrothermal liquefaction reaction network of microalgae 28

Figure 2.4 Hydrothermal liquefaction reaction network of microalgae 28

Figure 2.5 Overall reactions associated catalytic bio-oil upgrading 29

Figure 3.1 Growth and histological characteristics of TP compared to WT in different growing conditions 48

Figure 3.2 Deconvolution of DTG curves of WT and TP at heating rate of 30 K/min 52

Figure 3.3 Thermogravimetric and differential thermogravimetric curves for Sagarssum sp at heating rates of 5, 10, 15, and 20 C /min 53

Figure 3.4 KAS (a, c) and FWO (b, d) plots of WT sample (a, b) and TP(c, d) for different values of conversion 56

Figure 3.5 Apparent activation energy as a function of conversion obtained by KAS and FWO methods 58

Figure 3.6 Classed of chemical compounds in the bio-oil prepared at 400 oC and 3 min (a) carbohydrates-derivatives, and (b) lignin-derivatives 64

Figure 3.7 Schematic of pyrolysis reaction network .66

Figure 3.8 Experimental (discrete points) and calculated (solid lines) yields of solid, bio-oil, and gas products as a function of reaction time at various reaction temperatures of WT (a, b, c) and TP (d, e, f): 360 C (a, d), 380 C (b, e), and 400 C (c, f) 68

Figure 3.9 Model –predicted yields from pyrolysis of WT (a, b, c) and TP (d, e, f): solid residue (a, d), bio-oil (b, e), and gas (c, f) 72

Figure 4.1 TGA and DTG curves for Aurantiochytrium sp KRS101 at heating rates of 5, 10, 15, 20 oC/min 90

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Figure 4.2 (a) (a) Deconvolution of DTG curve for Aurantiochytrium sp at the

heating rate of 20 oC/min; (b) DTG curves of Aurantiochytrium sp and

lipid-extracted Aurantiochytrium sp at the heating rate of 20

oC/min… 91

Figure 4.3 Arrhenius plots of ln(β/T2) versus 1/T for determination of activation energies at various conversions by means of the KAS method… 94

Figure 4 4 Reaction network for pyrolysis of microalgae Aurantiochytrium sp 100

Figure 4.5 Plot of first –order kinetic of the pyrolysis of Aurantiochytrium sp 103

Figure 4.6 Plot of second-order kinetic of the pyrolysis of Aurantiochytrium sp KRS 101… 103

Figure 5.1 Schematic diagram of experimental setup 114

Figure 5.2 Schematic procedure for the reaction and product separation 115

Figure 5.3 FT- IR spectrum of microalgae Aurantiochytrium sp KRS101 119

Figure 5.4 FT- IR spectrum of microalga Tetraselmis sp 119

Figure 5.5 1H- NMR spectrum of the bio-oil produced from HTL of Aurantiochytrium sp KRS 101 125

Figure 5.6 Selectivities of carbohydrate derivatives, lipid derivatives, and protein derivatives of the LO and HO products obtained from the HTL of Tetraselmis sp at 350 oC for 10min 132

Figure 5.7 FT- IR spectrum of LO, HO and AP fractions from HTL of Tetraselmis sp 134

Figure 5.8 Aqueous-phase product from HTL of Tetraselmis sp after 2 day of deposition: a) 250 oC, 10min, b) 300 oC, 10min, and c) 350 oC, 10min 136

Figure 5.9 Hydrothermal liqu3faction reaction of Aurantiochytrium sp 137

Figure 5.10 Experimental (discrete points) and calculated (solid points) yields of liquefaction product obtained from HTL of Aurantiochytrium sp as a function of reaction time at various reaction temperatures: a) 250 C, b) 300 C, c) 350 C, and d) 400 C 140

Figure 5.11 Model-predicted yields from hydrothermal liquefaction of Aurantiochytrium sp KRS101: a) solid residue, b) bio-oil product, c) aqueous-phase product, and d) gaseous product… 145

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Figure 5.12 Hydrothermal liquefaction reaction network for HTL of Tetraselmis

sp… 146 Figure 5.13 Experimental (discrete points) and calculated (solid lines) yields of

liquefaction products obtained from HTL of Tetraselmis sp as a

function of reaction time at various reaction temperatures: a) 250 oC,

b) 300 oC, and c) 350 oC 149 Figure 5.14 Comparison of experimental and calculated product yields from HTL

of Tetraselmis sp at various HTL conditions 150 Figure 5.15 Model-predicted yields from the hydrothermal liquefaction of

Tetraselmis sp.: (a) solid residue, (b) aqueous phase product, (c) light

oil, (d) heavy oil, (e) total biocrude, and (f) gas product 155 Figure 6.1 The shematic diagram of the spray pyrolysis appratus 167 Figure 6.2 The schematic of HDO experiment 169 Figure 6.3 Textural properties of SP-derived supports and Mo/Al2O3TiO2

catalysts: (a) N2 adsorption and desorption isotherms, and (b) pore

size distributions 172 Figure 6.4 N2 adsorption–desorption isotherms of 80Al20Ti binary support,

Mo/(80Al20Ti) and Mo/(80Al20Ti)IM catalysts The inset figure

reveals pore size distributions of these samples 173 Figure 6.5 FE-SEM images of SP-derived Mo/Al2O3TiO2 catalysts: (a)

Mo/Al2O3, (b) Mo/(95Al5Ti), (c) Mo/(90Al10Ti), (d)

Mo/(80Al20Ti), (e) Mo/(70Al30Ti), and (f) Mo/TiO2 176 Figure 6 6 SEM secondary electro (SE) images and EDX dot mappings of metal

species (Al, Ti, and Mo): (a) Mo/(95Al5Ti) catalyst, and (b)

Mo/(80Al20Ti) catalyst 177 Figure 6 7 XRD patterns of SP-derived supports and Mo/Al2O3TiO2 catalysts:

(a) γ- Al2O3, (b) Mo/Al2O3, (c) Mo/(95Al5Ti), (d) Mo/(90Al10Ti),

(e) Mo/(80Al20Ti), (f) Mo/(70Al30Ti), (g) Mo/TiO2, and (h) TiO2 179 Figure 6.8 XRD patterns of (a) 80Al20Ti support, (b) Mo/(80Al20Ti) catalyst,

and (c) Mo/(80Al20Ti)IM catalyst 179

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Figure 6 9 FT–IR spectra of SP-derived supports and Mo/Al2O3TiO2 catalysts,

and bulk MoO3: (a) γ- Al2O3, (b) Mo/Al2O3, (c) Mo/(95Al5Ti), (d)

Mo/(90Al10Ti), (e) Mo/(80Al20Ti), (f) Mo/(70Al30Ti), (g)

Mo/TiO2, (h) TiO2, and (k) bulk MoO3 181 Figure 6.10 Mo 3d XPS spectra of SP-derived supports and Mo/Al2O3TiO2

catalysts: (a) Mo/Al2O3, (b) Mo/(95Al5Ti), (c) Mo/(90Al10Ti), (d)

Mo/(80Al20Ti), (e) Mo/(70Al30Ti), and (f) Mo/TiO2 183 Figure 6.11 Ti 2p XPS spectra of SP-derived Mo/Al2O3TiO2 catalysts and pure

TiO2 support: (a) Mo/(95Al5Ti), (b) Mo/(90Al10Ti), (c)

Mo/(80Al20Ti), (d) Mo/(70Al30Ti), (e) Mo/TiO2, and (f) pure TiO2 183 Figure 6 12 XPS spectra of the Mo/(80Al-20Ti) before and after reduction: (a) O

1s and (b) Mo 3d 186 Figure 6.13 TPR profiles of SP-derived Mo/Al2O3TiO2 catalysts: (a) Mo/Al2O3,

(b) Mo/(95Al5Ti), (c) Mo/(90Al10Ti), (d) Mo/(80Al20Ti), (e)

Mo/(70Al30Ti), and (f) Mo/TiO2 188 Figure 6.14 NH3 – TPD profiles of calcined SP-derived catalysts 190 Figure 6.15 HDO conversion and product distribution of Palmitic acid over

different catalysts under the following reaction conditions: Palmitic

acid (0.5g), heptane (45ml), catalyst (0.1g), H2 (4MPa), reaction

temperature (280 C), reaction time (4h), and stirring at 300 rpm 193 Figure 6.16 A general reaction mechanism for HDO of Palmitic acid over

Mo/Al2O3–TiO2 catalysts 195 Figure 6.17 HDO conversion and product distribution of Palmitic acid at different

reaction temperatures over (a) Mo/(90Al10Ti) catalyst and (b)

Mo/(80Al20Ti) catalyst, under the following reaction conditions:

Palmitic acid (0.5g), heptane (45ml), catalyst (0.1g), H2 (4MPa),

reaction time (4h), and stirring at 300 rpm 196 Figure 6.18 HDO conversion and product distribution of Palmitic acid over

Mo/(80Al20Ti) catalyst with cycling runs under the following

reaction conditions: Palmitic acid (0.5g), heptane (45ml), H2 (4MPa),

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reaction temperature (280 C), reaction time (4h), and stirring at 300

rpm 198 Figure 6.19 XPS spectra of freshly reduced and spent catalyst: (a) 3d Mo and (b) O

1s 199