BIO-BASED PHENOLIC RESINS AND ADHESIVES DERIVED FROM FORESTRY RESIDUES/WASTES AND LIGNIN (Spine title: Bio-based Phenolic Resins and Adhesives from Lignin) (Thesis format: Integrated-Article) by Shuna Cheng Graduate Program in Forest Science A thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy Faculty of Natural Resources Management Lakehead University Thunder Bay, Ontario, Canada Shuna Cheng  2011 ABSTRACT The work presented here aims to produce bio-phenolic compounds from forestry biomass (residues, wastes and lignin), and substitute petroleum-based phenol with the bio-phenolic compounds to produce high quality bio-based phenol formaldehyde (PF) resins. For the production of bio-phenolic compounds from biomass, alcohol (methanol or ethanol) and water showed synergistic effects on biomass direct liquefaction. 65 wt% of bio-oil and a biomass conversion at > 95% were obtained at 300 C for 15 min in the 50%/50% (w/w) co-solvent of either methanol-water or ethanol-water. At a temperature higher than 300 C, conversion of bio-oil to char was significant via re-polymerization reactions. The Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography-Mass Spectroscopy (GC-MS) analyses of the obtained bio-oils confirmed the presence of primarily phenolic compounds and their derivatives (such as benzenes), followed by aldehyde, long-chain (and cyclic) ketones and alcohols, ester, organic acid, and ether compounds. The Gel Permeation Chromatography (GPC) results suggested that hot-compressed ethanol as the liquefaction solvent favored lignin degradation into monomeric phenols. The X-ray Diffraction (XRD) patterns of Eastern White Pine (Pinus strobus L.) wood before and after the liquefaction displayed that the cellulosic structure of the feedstock was completely converted into amorphous carbon at around 300 C, and into crystalline carbon at about 350 C. The bio-oil was successfully applied to synthesize bio-oil phenol formaldehyde (BPF) resins up to 75 wt% substitution for phenol. All the BPF resins showed similar physical-chemical properties, such as viscosity, pH value, free formaldehyde level, non-volatile contents, thermal behavior and thermal stability as the pure phenol-formaldehyde (PF) resin. Particularly for the bond strength (dry and wet tensile strength), all the BPF adhesives demonstrated similar or better strength than the PF adhesive. In order to further improve the reactivity of the bio-oil for production of higher quality phenolic resole resins based on the previous work, the bio-oil was methylolated i by treating with formaldehyde before resinification. The results showed that the methylolation treatment improved the thermal stability and decreased curing temperature of the resins. But the treatment slightly increased the viscosity and slightly decreased the bond strength of the methylolated bio-oil PF (MBPF) resins, depending on the methylolated bio-oil ratio in the formula. Dry/wet bond strengths of MBPF resins at a phenol substitution ratio up to 60 wt% exceeded or were still comparable to those of the pure PF resin. Although the substitution ratio is lower than that for the BPF resin, it is still higher than that (< 50 wt%) reported by other researchers. For the production of bio-phenolic compounds from alkali lignin (AL), 89% degraded lignin (DL) was achieved by hydrothermal treatment in 50/50 (v/v) water-ethanol at 300 oC under 5 MPa H . The relative molecular weights of the lignin were markedly reduced 2 from its original M and M of 60,000 g/mol and 10,000 g/mol, respectively, to M : 1010 w n w g/mol and M : 415 g/mol for the DL. The reaction time had little effects on the DL yields n and properties. 300-325 oC and 400 oC appeared to be the optimal temperature for the process in 50/50 (v/v) water-ethanol and pure ethanol, respectively. The catalyst tested in this work did not significantly affect the yield of DLs, but slightly reduced the relative molecular weights of the DLs. For the production of bio-phenolic compounds from organosolv lignin (OL), 81 % of DL with very low relative molecular weights (M 181 n g/mol and M 568 g/mol) was produced at 340 oC in 50/50 (v/v) water-ethanol with w Ni10/AC catalyst. The reaction temperature had significant effects on the yield and molecular-weight distributions of the DL. Faster heating and stirring had a positive effect on the yield of DL, particularly the stirring. The bio-phenolic compounds derived from the OL were then used to replace phenol in the production of phenolic resole resins. All the degraded lignin-phenol-formaldehyde (DLPF) and the organosolv lignin-phenol-formaldehyde (OLPF) resole resins have similar physical-chemical properties as the pure PF resin. The plywood samples glued with the OLPF and DLPF adhesives with a phenol replacement ratio up to 75 wt% showed higher dry and wet tensile strengths than that of the PF resin. Although the OLPF adhesives have better bond strengths and thermal stability than DLPF adhesives, the DLPF resins have lower free formaldehyde content and a lower curing temperature. ii In this study, formic acid that can act as a hydrogen donor at elevated temperatures was employed for degradation of AL and OL in the medium of sub-/super-critical 50/50 (v/v) water-ethanol. With formic acid, 77 % yield of DL with the relative molecular weights of M 295 g/mol and M 816 g/mol was obtained from the degradation treatment of AL at n w 300 oC. For the degradation treatment of OL, a high yield of DL (80 %) with low relative M 150 g/mol and M 464 g/mol was successfully achieved with formic acid at 350 oC. n w The use of formic acid was found to be effective for increasing the DL yields while suppressing the formation of solid residues compared with the use of gaseous hydrogen, likely because the in situ formed hydrogen from formic acid can prevent the recombination of reaction intermediates. iii ACKNOWLEDGEMENTS The work presented in this dissertation would never have been accomplished without many people‘s contributions. They are the ones who have been there throughout my PhD studies and have helped me walk to its end. I would like to thank them for their support and efforts. First, I am grateful to my primary advisor, Dr. Chunbao (Charles) Xu. He offered me a ―spacious‖ environment to work on my PhD research, illuminated and encouraged me with novel ideas, and gave me an excellent guide to be a real scientist. He also provided me every chance he could to meet people in the research field and to meet lots of related industry partners. During the past 3 years, I have attended 8 international and Canadian academic and industrial conferences increasing my knowledge about the directions of the research field and the requirements of the market. His positive thinking and wide experiences have always been an inspiration to me. I would also like to express my special thanks to Dr. Mathew Leitch for guiding me and sharing his knowledge and enthusiasm on many occasions during the course of my PhD research. He is an excellent wood scientist from whom I know better about biomass and lignin. He is either a supervisor or a friend. He always encouraged me for any little progress I have made and gave me useful suggestions. He also helped me improve my English throughout this study. On a side note he also taught me how to fish with others in the group, which was fun. His guidance, patience, and time were invaluable in the completion of this work. I could not achieve the progress without his assistance. I would like to thank my other PhD thesis committee member Dr. Reino Pulkki for his time and effort spent on my thesis work. I am also grateful for the financial support from the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) through the New Directions Research Program Grant, and from the industry partners of Arclin Limited and Green Field Ethanol. The author would also like to acknowledge the financial support from FedNor, Northern Ontario Heritage Fund Corporation (NOHFC) and Natural Sciences and Engineering iv Research Council (NSERC) Biomaterials and Chemcials Strategic Research Network (Lignoworks). In addition, special thanks go to Dr. Mark Anderson at Arclin Canada for his advice and support of my research. I appreciate Mr. Ain Raitsakas for teaching me how to use the Fourier Transform Infrared Spectroscopy (FTIR) equipment. I also want to thank Mr. Michael Sorokopud for helping me with the elemental analysis and Nuclear Magnetic Resonance (NMR) analysis, and Mr. Garry Rathje for his valuable assistance during my experimental stages of the project. I am indebted to the post-doctoral fellows Dr. Zhongshun Yuan and Dr. Mingcun Wang for their assistance in my PhD research. I also want to thank my colleagues Dr. Hanning Li, Dr. Hui Chen, YunYang, Linghong Zhang, Ian D‘cruz, Carolynne Wilks, Shanghuan Feng for their kind suggestion and help. I am also grateful to the department administrative assistant LoisAnn Bender and Eva Scollie for their assistance and time. I want to thank the friendship from Weijue Gao, Yujia Chen, Jenny Lo, Guo Li, Yong Luo, Xi Chen, Xiaoran Dong, Junlin Li, Scott Miller, Steven Hosegood, Jim Riffel, and Wei Xiang. I am also thankful for my friends at home that have our friendship for many years. I hope they could forgive my absence in their wedding and many important occasions. The project of pursuing a PhD degree overseas would never have come to my mind without the guidance, encouragement and support of my MSc professor Dr. Shenyuan Fu. He has been a positive and important influence on the course of my life. He first inspired my interest in research through supervising my MSc thesis and through his incredible enthusiasm. Last but not least, I want to express my deepest gratitude to my mom and my lovely niece. My mom gave me her best understanding upon my studying overseas. Without her support and understanding, I would never have been able to go this far. v TABLE OF CONTENTS ABSTRACT ................................................................................................................ i ACKNOWLEDGEMENTS ................................................................................. iv TABLE OF CONTENTS ..................................................................................... vi LIST OF FIGURES AND SCHEMES ....................................................... x LIST OF TABLES .................................................................................. xiii LIST OF ABBREVIATIONS ................................................................... xv CHAPTER 1. INTRODUCTION............................................................... 1 1.1 Background .............................................................................................................. 1 1.2 Substitution for Phenol with Bio-based Phenolic Compounds from Forestry Residues in the PF resins ......................................................................................... 3 1.3 Substitution for Phenol with Bio-based Phenolic Compounds from Lignin in the PF resins ............................................................................................................. 5 1.4 Objectives ................................................................................................................. 7 1.5 Organization of the Thesis ...................................................................................... 7 1.6 References ................................................................................................................ 9 CHAPTER 2. LITERATURE REVIEW ................................................. 15 2.1 Chemistry of Phenol-Formaldehyde (PF) Resin Synthesis .................................. 15 2.1.1 Raw material .................................................................................................. 16 2.1.2 PF resole synthesis ......................................................................................... 19 2.1.3 PF resole resin curing chemistry..................................................................... 23 2.1.4 Thermal stability of cured PF resoles ............................................................. 24 2.1.5 Effects of synthesis parameters on Properties of PF Resoles ........................... 25 2.2 Biomass Pyrolysis and its Application in the Production of PF Resins ............... 28 2.2.1 Applications of fast pyrolysis oils in renewable PF Resins ............................. 29 2.2.2 Applications of vacuum pyrolysis oils in renewable PF Resins ....................... 30 2.3 Biomass Solvolytic Liquefaction and its Applications in the Production of PF Resins ..................................................................................................................... 31 2.3.1 Solvolysis under low temperatures and atmospheric pressure .......................... 31 2.3.2 Solvolysis in a hot-compressed and sub-/super-critical fluid ............................ 32 2.4 Extraction, Modification and Degradation of Lignin and Its Application in the Production of PF Resins ........................................................................................ 35 2.4.1 Lignin extraction ............................................................................................. 36 2.4.2 Lignin modification for PF resins production .................................................. 37 2.4.3 Lignin degradation for PF resins production .................................................... 38 2.5 Concluding Remarks ............................................................................................. 43 2.6 References .............................................................................................................. 44 CHAPTER 3. HIGHLY EFFICIENT LIQUEFACTION OF WOODY vi BIOMASS IN HOT-COMPRESSED ALCOHOL-WATER CO-SOLVENTS .................................................................................................. 54 3.1 Abstract .................................................................................................................. 54 3.2 Introduction ........................................................................................................... 54 3.3 Experimental Section............................................................................................. 58 3.3.1 Materials ........................................................................................................ 58 3.3.2 Liquefaction operation and product separation ............................................... 59 3.3.3 Characterization of the liquid and solid products ............................................ 60 3.4 Results and Discussion........................................................................................... 61 3.4.1 Effects of solvent types and compositions ...................................................... 61 3.4.2 Effects of reaction temperature....................................................................... 65 3.4.3 Effects of solvent-to-biomass ratio ................................................................. 66 3.4.4 Characterizations of liquefaction products ...................................................... 68 3.5 Conclusions ............................................................................................................ 75 3.6 Acknowledgements ................................................................................................ 77 3.7 References .............................................................................................................. 77 CHAPTER 4. USING BIO-CRUDE DERIVED FROM WOODY BIOMASS TO SUBSTITUTE PHENOL AT A HIGH SUBSTITUTION LEVEL FOR PRODUCTION OF BIO-BASED PHENOLIC RESOLE RESINS ...................................................................... 83 4.1 Abstract .................................................................................................................. 83 4.2 Introduction ........................................................................................................... 83 4.3 Materials and Methods .......................................................................................... 86 4.3.1 Materials ........................................................................................................ 86 4.3.2 Preparation of phenolic bio-oil from woody biomass by direct liquefaction .... 87 4.3.3 Synthesis of BPF resole resins using woody biomass derived bio-oil ............. 87 4.3.4 Characterization of the BPF and PF resole resins ........................................... 88 4.3.5 Evaluation of tensile strength of plywood samples bonded with BPF resins ... 89 4.4 Results and Discussion........................................................................................... 90 4.4.1 Resin characterization .................................................................................... 90 4.4.2 Evaluation of adhesive bonds ......................................................................... 99 4.5 Conclusions .......................................................................................................... 101 4.6 Acknowledgements .............................................................................................. 102 4.7 References ............................................................................................................ 103 CHAPTER 5. SYNTHESIS OF BIO-BASED PHENOLIC RESINS/ADHESIVES USING METHYLOLATED WOOD-DERIVED BIO-OIL ...............................................................................106 5.1 Abstract ................................................................................................................ 106 5.2 Introduction ......................................................................................................... 106 5.3. Materials and Methods ....................................................................................... 109 5.3.1 Materials ...................................................................................................... 109 5.3.2 Preparation of methylolated bio-oil .............................................................. 110 5.3.3 Preparation of MBPF resole resins ............................................................... 110 vii 5.3.4 Characterizations of MB and MBPF resins ................................................... 111 5.4 Results and Discussion......................................................................................... 114 5.4.1 Characterizations of the raw bio-oil and the methylolated bio-oil ................. 114 5.4.2 Characterizations of the MBPF resole resins ................................................ 117 5.4.3 Evaluation of bond strength of plywood samples glued with MBPF resins ... 126 5.5 Conclusions .......................................................................................................... 128 5.6 Acknowledgements .............................................................................................. 129 5.7 References ............................................................................................................ 129 CHAPTER 6. HYDROTHERMAL DEGRADATION OF ALKALI LIGNIN TO BIO-PHENOLIC COMPOUNDS IN SUB-/SUPER-CRITICAL ETHANOL AND WATER-ETHANOL CO-SOLVENT ............................................................................................................133 6.1 Abstract ................................................................................................................ 133 6.2 Introduction ......................................................................................................... 133 6.3 Materials and Methods ........................................................................................ 135 6.3.1 Materials ...................................................................................................... 135 6.3.2 Catalyst preparation ..................................................................................... 136 6.3.3 Lignin degradation experiments ................................................................... 137 6.3.4 Products separation ...................................................................................... 138 6.3.5 Characterizations of DL ............................................................................... 138 6.4. Results and Discussion........................................................................................ 139 6.4.1 Effects of solvent composition ..................................................................... 139 6.4.2 Effects of reaction time ................................................................................ 141 6.4.3 Effects of reaction temperature..................................................................... 143 6.4.4 Effects of catalyst......................................................................................... 147 6.4.5 Characterizations of DLs .............................................................................. 149 6.4.6 Alkali lignin degradation mechanism in sub-/super-critical water-ethanol .....155 6.5 Conclusions....................................................................................................................156 6.6 Acknowledgements .............................................................................................. 157 6.7 References ............................................................................................................ 157 CHAPTER 7. PRODUCTION OF GREEN PHENOLIC RESINS AND ADHESIVES USING BIO-PHENOLIC COMPOUNDS FROM LIGNIN/FORESTRY RESIDUALS AS A SUBSTITUTE FOR PHENOL AT A HIGH SUBSTITUTION RATIO ..........................160 7.1 Abstract..........................................................................................................................160 7.2 Introduction ..................................................................................................................160 7.3 Materials and Methods ................................................................................................162 7.3.1 Materials and catalyst preparation ................................................................ 162 7.3.2 Catalytic hydrothermal treatment of lignin and product separation ............... 163 7.3.3 Synthesis of phenolic resole resins ............................................................... 165 7.3.4 Characterizations of the DL and the phenolic resole resins ........................... 165 7.4 Results and Discussion......................................................................................... 166 7.4.1 Effects of catalyst and temperature on OL degradation .................................. 167 viii 7.4.2 Effects of stirring and heating equipment of reactor on OL degradation ........ 169 7.4.3 1H NMR analysis of OL and DL ................................................................... 170 7.4.4 Characterizations of OLPF, DLPF and PF resole resins ................................. 172 7.4.5 Evaluation bond strength of OLPFs, DLPFs and PF ...................................... 176 7.5 Conclusions .......................................................................................................... 177 7.6 Acknowledgements .............................................................................................. 178 7.7 References ............................................................................................................ 179 CHAPTER 8. DE-POLYMERIZATION OF LIGNIN WITH FORMIC ACID IN SUB-/SUPER-CRITICAL SOLVENT OF WATER-ETHANOL................................................................................................182 8.1 Abstract ................................................................................................................ 182 8.2 Introduction ......................................................................................................... 182 8.3 Materials and Methods ........................................................................................ 183 8.3.1 Materials ...................................................................................................... 183 8.3.2 Degradation of lignin ................................................................................... 185 8.3.3 Analytical methods ...................................................................................... 185 8.4 Results and Discussion......................................................................................... 186 8.4.1 Effects of formic acid on AL degradation ..................................................... 186 8.4.2 OL degradation ............................................................................................ 191 8.5 Conclusions .......................................................................................................... 193 8.6 Acknowledgements .............................................................................................. 194 8.7 References ............................................................................................................ 195 CHAPTER 9. CONCLUSIONS ............................................................ 197 CHAPTER 10. FUTURE WORK .......................................................... 202 PUBLICATIONS .................................................................................... 203 ix