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DICARBOXYLIC ACIDS PLATFORM CHEMICALS FOR VALORIZATION OF BIOREFINERY LIGNIN By RUOSHUI MA A dissertation submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY WASHINGTON STATE UNIVERSITY Gene and Linda Voiland School of Chemical Engineering and Bioengineering DECEMBER 2016 © Copyright by RUOSHUI MA, 2016 All Rights Reserved © Copyright by RUOSHUI MA, 2016 All Rights Reserved To the Faculty of Washington State University: The members of the Committee appointed to examine the dissertation of RUOSHUI MA find it satisfactory and recommend that it be accepted. Xiao Zhang, Ph.D., Chair Yong Wang, Ph.D. Cornelius F. Ivory, Ph.D. ii ACKNOWLEDGEMENT I would like to express my sincerest and deepest gratitude to those who have helped and supported me throughout my research and life: First, I would like to thank Dr. Xiao Zhang for offering me the opportunity to pursue my Ph.D degree. You are not only a great mentor of research, but also a mentor and friend of life. I am very grateful for your instruction, encouragement and support during the last four years. I believe I will benefit from the philosophy of life I learnt for the very rest of my career and life. Then, I want to thank all my committee members, Dr. Yong Wang and Dr. Cornelius F. Ivory for their guidance, support and priceless advices to the completeness of this thesis research. I would also like to thank Dr. Karthi Ramasamy, Dr. Feng Gao, Dr. Suh-Jane Lee from PNNL for instrumentation support and the results discussion during the research. Dr. Vincent. R. Hebert, Dr. Jinwen Zhang, and Dr. Michael P. Wolcott for their contribution to results discussion. I will specially thank all the members from Dr. Xiao Zhang’s group. Mond, Kuan-ting, Dr. Peipei Wang, Carlos, Melissa, Scott, Senthil, and all our intern students. You guys are wonderful labmates, officemates, friends, and colleagues. Thanks for being helpful and supportive to my thesis study. The last but not the least, I would save the deepest appreciation to my family. Yi, I cannot thank you more for being supportive during these years. You gave me strength to keep me up facing all the failures. My parents, thank you for always being supportive to any goal I pursued. You are the best parents. I love you all. I also want to thanks fund support: USDA NIFA (2011-68005-30416), Sungrant/DOT (T0013GA), NSF award (no 1454575). iii DICARBOXYLIC ACIDS PLATFORM CHEMICALS FOR VALORIZATION OF BIOREFINERY LIGNIN Abstract by Ruoshui Ma, Ph.D. Washington State University December 2016 Chair: Xiao Zhang, Ph.D. Despite decades of effort, commercial development of biomass-to-biofuel conversion processes is still not an economically viable proposition. The emerging biomass refinery industry will inevitably generate an enormous amount of lignin as the solid waste stream. Development of selective biorefinery lignin-to-bioproducts conversion processes will play a pivotal role in significantly improving the economic feasibility and sustainability of biofuel production from renewable biomass. Due to the aromatic skeleton of lignin, most previous lignin valorization studies were limited to converting lignin to monomeric phenolics. Aromatic ring opened structures such as dicarboxylic acids (DCA) have been overlooked, though commonly observed during conversion. This thesis presents a new pathway for producing DCA as a new group of platform chemicals for lignin valorization, and specifically aims to develop a systematic understanding of the reaction mechanisms and to identify the key hurdles to optimizing conversion. To achieve this goal, a variety of oxidant and catalyst combinations were screened for oxidative depolymerization and conversion. A set of representative biorefinery lignin obtained from various commercial biorefineries for testing; the lignin samples were fully characterized by a number of selected analytical techniques. Representative monomeric and dimeric model compounds were used to help iv identify key intermediates and interpret the reaction mechanisms. Statistical analysis methods were developed as a new approach for providing quantitative guidance in lignin depolymerization research by relating and predicting lignin structure and reactivity. Techno-economic analysis (TEA) was conducted to direct future work toward addressing key bottlenecks in process costs. The new insights gained in this work inspired the development of novel catalytic oxidation pathways and processes to convert biorefinery lignin to DCA as a new group of platform chemicals/intermediates, enabling sustainable biofuel production from lignocellulosic biomass. These findings also provide new direction toward lignin partial depolymerization. v TABLE OF CONTENTS ACKNOWLEDGEMENT ............................................................................................................. iii ABSTRACT ................................................................................................................................... iv CHAPTER ONE: INTRODUCTION ............................................................................................. 1 1.1 Booming Modern Biorefinery ................................................................................................... 1 1.2 What is Lignin? ......................................................................................................................... 2 1.3 Current Understanding of Lignin Depolymerization Chemistry in Paper Making ................... 4 1.4 Economical Potential Using Oxidative Lignin Depolymerization ......................................... 11 1.5 Catalysts for Lignin Oxidative Conversion ............................................................................ 12 1.5.1 Inorganic Metal-based Catalysts .................................................................................. 13 1.5.2 Organometallics ............................................................................................................ 18 1.5.3 Organocatalysts ............................................................................................................ 25 1.6 Thesis Objectives ........................................................................................................... 28 1.7 Organization of the dissertation ..................................................................................... 29 CHAPTER TWO: MATERIALS & METHODOLOGY ............................................................. 35 2.1 Preparation of Biorefinery lignin ................................................................................... 35 2.2 Characterization of Biorefinery lignin ........................................................................... 39 2.2.1 Lignin Composition Analysis ................................................................................. 39 2.2.2 Spectroscopic Methods ........................................................................................... 48 vi 2.2.3 Analysis of Physical Properties .............................................................................. 53 2.2.4 Separation of Identification of Low-Molecular Weight Fragments and Model Compounds ............................................................................................................................ 56 CHAPTER THREE: SELECTIVE CONVERSION OF BIOREFINERY LIGNIN TO DICARBOXYLIC ACIDS ........................................................................................................... 60 3.1 Abstract ................................................................................................................................... 60 3.2 Introduction ............................................................................................................................. 60 3.3 Results and Discussion ........................................................................................................... 62 3.4 Conclusion .............................................................................................................................. 71 3.5 Experimental Summary .......................................................................................................... 72 CHAPTER FOUR: PERACETIC ACID DEPOLYMERIZATION OF BIOREFINERY LIGNIN FOR PRODUCTION OF SELECTIVE MONOMERIC PHENOLIC COMPOUNDS ............... 74 3.1 Abstract ................................................................................................................................... 74 3.2 Introduction ............................................................................................................................. 75 3.3 Result and Discussion ............................................................................................................. 77 4.4 Conclusions ............................................................................................................................. 94 4.5 Experimental Summary .......................................................................................................... 94 CHAPTER FIVE: QUALITATIVE AND QUANTITATIVE RELATIONSHIPS BETWEEN LIGNIN DEPOLYMERIZATION/AROMATIC-RING OPENING REACTIVITY AND THEIR STRUCTURAL CHARACTERISTICS: FUNCTIONAL GROUP，INTER-UNIT LINKAGE AND MACROMOLECULAR ................................................................................................................. 96 5.1 Introduction ............................................................................................................................. 96 5.2 Results and Discussion
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