Projekt 2 im Rahmen des Center for Dynamic Systems (CDS) ZS/2023/12/182075: Transforming Waste into High-Value Products: Harnessing Lignin, Lignocellulose, and Black Liquor for Sustainable Chemicals and Polymer Innovations - Conversion of (ligno/hemi)cellulose to building blocks and platform chemicals (Projektbereich 1, Teilprojekt 1.4)

Lignin, Hemicellulose und Lignocellulose sowie Schwarzlauge sind Abfallprodukte der Zellstoff- und Papierindustrie (ca. 50 Millionen Tonnen pro Jahr) und stellen eine erhebliche Herausforderung für die Umwelt dar. Derzeit werden Lignin-Nebenprodukte und Schwarzlauge überwiegend durch energieintensive Verdampfung und anschließende Verbrennung verwertet. Lignin ist jedoch die reichhaltigste natürliche Quelle für aromatische Verbindungen und bietet daher eine nachhaltige Möglichkeit zur Herstellung aromatischer Chemikalien wie Vanillin, p-Hydroxybenzoesäure und Syringasäure. Dies eröffnet auch Wege zur Herstellung nachhaltiger Kunststoffvorläufer und -produkte unter Verwendung funktioneller Ligninpolymere und -oligomere wie Caprolactam. Die Integration der Ligninverwertung mit erneuerbaren Energiequellen wie Solar- und Windenergie bietet eine vielversprechende Strategie zur Erreichung der CO2-Neutralität. Ziel dieses Projekts ist die Entwicklung eines neuen elektrochemischen Depolymerisationsverfahrens zur Behandlung von Lignin bei Raumtemperatur und unter Umgebungsbedingungen. Es werden wertvolle Produkte wie Syringyl und Guaiacyl sowie Wasserstoff erwartet.

Ziele:

• Durchführung von eigener experimentelle Arbeiten in homo- und heterogen katalysierten Systemen auf Basis biogener Reststoffe mit hohem Schwierigkeitsgrad auf der Grundlage eigener konzeptioneller Überlegungen
• Netzwerkanalyse und Entwicklung (mechanistischer) kinetischer Modelle, Modellreduktion und Parametrisierung für die modellbasierte Reaktor- und Prozessentwicklung
• Betrieb modularer Versuchsanlagen und insbesondere Reaktionskalorimetrie im Nieder- und Hochdruckbereich zur Untersuchung von Reaktionskinetik mit operande-Spektroskopie und HPLC-/GC-MS-Analytik, Thermochemische Untersuchungen

Project 2 with Center for Dynamic Systems (CDS) ZS/2023/12/182075: Fractionation and valorization of black liquor and lignin (project area 1, subproject 1.4)

Black liquor, a waste byproduct generated in the pulp and paper industries (approximately 50 million tons per year), poses significant environmental challenges. Currently, the predominant method for utilizing lignin side streams and black liquor involves incineration after energy-intensive evaporation. However, lignin, being the most abundant natural source of aromatic compounds, presents a sustainable opportunity for producing aromatic chemicals such as vanillin, p-hydroxybenzoic acid, and syringic acid. This also opens pathways for creating sustainable plastic precursors and products using functional lignin polymers and oligomers, like caprolactam. Integrating lignin conversion with renewable energy sources, such as solar and wind power, offers a promising strategy for achieving carbon neutrality. The aim of this project is to develop a new electrochemical depolymerization process for treating lignin, at room temperature and under ambient conditions. Valuable products are expected, like syringyl and guaiacyl as well as hydrogen.

(Ligno/Hemi-)cellulose will be used to develop innovative reactors and processes for synthesizing of urgently needed bio-based building blocks and platform chemicals (e.g., furfural, ethoxy methyl furfural, butyl levulinate,..) for which no industrial processes exist. The synthesis is characterized by multistep dehydrations and esterifications based on suitable catalysts (homo-, hetero- (e.g. lignin-based (WP5), enzyme-catalytic) and results in complex reaction networks and kinetic analysis (WP4) depending on the purity and composition of raw material. Challenging are the reversible and irreversible side reactions taking place depending on the process conditions, as well as the identification of (ligno/hemi)cellulose oligomers and eventual monomers, and their degree of functionalization that form during the degradation. Reducing the water concentration using organic co- or removing the water formed in situ by process integration in single- or multistage processes is promising. Exemplarily, the conversion lignin to its building blocks will yield unsaturated monomers like p-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol, of which the former one will be the focus of resynthesis and (re-)polymerization studies, particularly, to yield lignin macromers (via the dehydrogenation polymer synthesis pathway) of defined molecular weight as future reference substances for mass spectrometry and size exclusion chromatography.

Aims:

• Conducting independent experimental work in homo- and heterogeneously catalyzed systems based on biogenic residues with a high degree of difficulty, based on independent conceptual considerations
• Network analysis and development of (mechanistic) kinetic models, model reduction, and parameterization for model-based reactor and process development
• Operation of modular pilot plants, in particular reaction calorimetry in the low and high pressure range for the investigation of reaction kinetics using operande spectroscopy and HPLC/GC-MS analysis, thermochemical investigations