An Integrated Approach for Added-Value Products from Lignocellulosic Biorefineries: Vanillin, Syringaldehyde, Polyphenols and Polyurethane

This book offers the state of the art on the progress and accomplishments of 25 years of research at the Associate Laboratory LSRE-LCM – Laboratory of Separation and Reaction Engineering – Laboratory of Catalysis and Materials on lignin conversion to value-added products and their downstream separation. The first valorisation pathway presented for lignin is its partial depolymerisation by oxidation for the production of low molecular weight phenolic compounds, such as vanillin and syringaldehyde, and the second one is the lignin application as macromonomer for polyurethane synthesis. In this book, the authors present the integration of these two valorisation pathways as an exclusive vision of LSRE-LCM resulting from hands-on experience on reaction and separation processes: the integrated process for lignin valorisation. In this perspective, the lignin is oxidized to simultaneously produce syringaldehyde and vanillin, and the obtained by-products to produce a polyol for lignin-based polyurethanes, completing the lignin value chain. On the perspective of pulp mill-related biorefineries, a valorisation route for eucalyptus bark is also presented, focusing on LSRE-LCM experience on extraction and separation of bioactive polyphenols, giving some insights about further integration of extracted bark on biorefining operations. 1. Prof. Dr. Alrio Egdio Rodrigues: Emeritus Professor at the University of Porto and former Director of the Associate Laboratory LSRE-LCM. He graduated in ChE at the U. Porto (1968) and is Docteur-Ingenieur from U. Nancy (1973). He directed more than 60 PhD students and published more than 550 papers, several patents with h-index 61 (Scopus). He edited 5 books and is author of Perfume Engineering (2012) and Simulated Moving Bed Technology (2015) with Elsevier, Moving Finite Element Method with CRC Press (2016) and Sorption Enhanced Reaction Processes with World Scientific Publishing (2017). His research interest cover Cyclic Adsorption Processes, Reaction Engineering, System Dynamics, Product Engineering, Perfume Engineering and Lignin Valorization, topic of this book. 2. Prof. Dr. Maria Filomena Barreiro: Filomena Barreiro (ORCID ID: 0000-0002-6844-333X) graduated in Chemical Engineering in 1990 at the Faculty of Engineering, University of Porto (FEUP). In 2000, and also at FEUP, she obtained the Ph.D. She joined the Polytechnic Institute of Bragana (IPB) in 1995 where she is presently Coordinator Professor at the Chemical and Biological Department (DTQB), and Vice-Coordinator of the Mountain Research Center (CIMO). As member of the research staff of the Associate Laboratory LSRE-LCM she carried out work on the integrated process for lignin valorization, mainly concerning lignin valorization in polymeric materials, such as polyols and polyurethanes. 3. Dr. Paula Cristina de Oliveira Rodrigues Pinto: Paula Pinto is technological R&D coordinator at RAIZ, part of The Navigator Company, since 2016, working on research areas of pulp, papermaking, office paper and tissue, and biorefinery. Previously she was Associated Researcher at Associate Laboratory LSRE-LCM for 7 years (2009-2016) working on lignin conversion to bio-based products and valorization of bark polyphenols as project leader of industry-driven projects in biorefinery topic (http://orcid.org/0000-0002-1561-4406). Before joining LSRE-LCM she worked as post-doctoral researcher in value-added chemicals from lignocellulosic materials at University of Aveiro and RAIZ (Forest and Paper Research Institute) after completing Ph.D in 2005 in the topic of kraft pulping, bleaching and wood components. 4. Dr. Carina Andreia Esteves da Costa: Carina Costa has graduated in Chemistry at the University of Aveiro (UA) in 2007. Two years later, she finished her Master in Analytical Chemistry also at UA. In 2017, Carina Costa concluded her Ph.D. in Chemical and Biological Engineering at the Faculty of Engineering, University of Porto (FEUP) with a thesis entitled “Vanillin and Syringaldehyde from Side Streams of Pulp and Paper Industries and Biorefineries”. Since then she is member of the research team of the Associate Laboratory LSRE-LCM, working in the study of lignin characterization and valorization through the production of high added-value chemicals. 5. Dr. Maria Ins Ferreira da Mota: Ins Mota graduated in Biological Engineering at the University of Minho, in Braga, Portugal, in 2005. After a 5 year period working in food safety consulting and quality management, in 2010 she started working in a Biorefinery research project related with the extraction of bioactive polyphenolic compounds from E. globolus bark and its fractionation and purification by membrane and adsorption processes at Associate laboratory LSRE-LCM. She obtained the integrated master degree in Chemical Engineering in 2011 at FEUP and in 2017 concluded her Ph.D degree in Chemical and Biological Engineering at FEUP. Her doctoral research was focused on fractionation and purification of oxidized lignin solution by chromatographic and membrane separation processes in order to obtain purified fractions of vanillin and syringaldehyde. Currently, she is a technological R&D researcher at RAIZ, part of The Navigator Company, since 2017, working on research areas of biorefinery and lignin. 6. Dr. Isabel Patrcia Fernandes: Isabel Fernandes (ORCID ID:0000-0002-0069-4503) graduated in Chemical Engineering at the Polytechnic Institute of Bragana (IPB) in 2003, and obtained the Master degree in Chemical and Biological Engineering, also at IPB, in 2008. In 2017, she completed the Ph.D degree in Chemical and Biological Engineering at the Faculty of Engineering University of Porto (FEUP). Her work is devoted to the synthesis of polymeric materials, namely polyurethanes and polyureas for various industrial applications, and focused on the development of biobased and biodegradable solutions, which include the use of lignin. 1.    Chemical pulp mills as biorefineries 1.1  General overview: delignification industrial processes 1.2  Side-streams and current recovery cycles of chemicals and energy in typical mills 1.3  The integration of new biorefinery processes in pulp industries 1.4  Lignin: the main side-stream from delignification processes 1.4.1          Types of lignins and up-to-date market 1.4.2          Lignins from new incoming delignification processes 1.4.3          The cost and the revenues of lignin separation from liquid side streams in a pulp mill 1.5  Lignin characterization and classification 1.5.1          Impact of delignification process on the structure of the lignin 1.5.2          Radar tool for lignin classification on the perspective of it valorization 1.5.3          Improving and recognizing the lignin quality in biorefineries 1.6  Bark: an unrecognized valuable lignocellulosic material 1.6.1          Chemical composition. The particular case of Eucalyptus globulus bark 1.6.2      &n bsp;   Current and potential commercial products from bark   2.    Integrated process for vanillin and syringaldehyde production from kraft lignin 2.1 Oxidation of lignin with O2 in alkaline medium 2.1.1      Batch oxidation                2.2.1.1 Kinetics and modelling of reaction in batch reactor for vanillin production                2.2.1.2 Syringaldeh yde as the main product from hardwood lignins                2.2.1.3 Oxidation of Eucalyptus globulus kraft pulping liquor versus kraft lignin 2.1.2      Oxidation in co-current gas-liquid flow structured packed reactor                2.1.2.1 Experimental and modelling of vanillin production                2.1.2.2 Experiments of oxidation of hardwood pulping liquor and lignins 2.2 Separation processes 2.2.1      Membrane separation of phenolates from depolymerized lignin 2.2.2      Ion exchange process for vanillin recovery 2.2.3      Adsorption and desorption of vanillin and syringaldehyde onto polymeric resins 2.3 The integrated process for complete lignin valorization into phenolic compounds and polyurethanes   3.    Polyurethanes from recovered and depolymerized lignins 3.1 Overview of strategies and opportunities 3.2 Lignin use as such    &n bsp;   3.2.1 Reactive filler in polyurethane foams        3.2.2 Additive to enhance biodegradability        3.2.3 Co-monomer to produce elastomers 3.3 Lignin use after chemical modification        3.3.1 Overview of lignin liquefaction processes        3.3.2 Oxypropylation as a viable route to produce liquid polyols        3.3.3 Screening of opportunities for oxypropylated lignin        3.3.4 Production of rigi d polyurethane foams 3.4. Lignin use after depolymerization 4.    Polyphenols from bark of Eucalyptus globulus 4.1 Composition of polar extracts 4.2 Extraction of polyphenols 4.2.1 Water and alkaline extractions: selectivity and concentration strategy 4.2.2 Ethanol/water extraction: process optimization for phenolic compounds 4.2.3 Screening for valuable applications: tanning proprieties and biological activity 4.3 Fractionation of ethanolic extracts from Eucalyptus globulus bark 4.3.1 Membrane processing 4.3.1.1 Resistance and cake build up analysis in the ultrafiltration of ethanol:water extract (80:20 v/v) 4.3.1.2 Application of ultrafiltration and nanofiltration to etanol/water extract (52:48 v/v) 4.3.2 Diafiltration and adsorption for purification and concentration of polyphenols   5.    Conclusions and future perspectives   6.    References