Development of lignin valorization processes as a source of aromatic building blocks for the production of bio-based polymers (ARRS J2-2492)

Duration of the project: 1. 9. 2020 – 31. 8. 2023

Value of the project: 2469 h, category C

Project partners:

• National institute of Chemistry, D13, Department of Catalysis and Chemical Reaction Engineering
• National Institute of Chemistry, D15, Slovenian NMR Centre

The project is focused on the development and systematic research with which we intend to show that a mixture of bio-aromatic compounds with well-defined chemical properties (eg molecular weight distribution, the concentration of free OH groups) can be obtained by appropriate selection of raw material and adapted lignin isolation, possible fractionation and depolymerization. ) and used for the synthesis of phenol-formaldehyde and epoxy resins and polycarbonates as a functional substitute for phenol or bisphenol-A. The researchers at the National Institute of Chemistry will isolate lignin from different sources of lignocellulosic biomass with different lignin structures using the organosol process. At the same time, a simple fractionation of the isolated lignin will be performed based on the molecular weight distribution. These fractions may be of interest for direct use in various formulations. They will continue to use several methods of depolymerization of isolated lignins, obtaining different mixtures of monomers in combination with oligomers. Hydrotreatment screening tests will be performed using different commercial metal catalysts on different supports, which will affect the final yield and selectivity of the product. They will also test a wide temperature and pressure range of hydrotreatment to optimize the reaction conditions. They will also perform oxidative screening tests on the most promising catalyst and under optimal conditions. A large database with performed experiments and characterization will provide us with an insight into the structure of lignin, operating conditions, and the relationship between the quantity and quality of the product.

At the FTPO, selected products will be tested in various polymer formulations. The synthesis of epoxy, phenol-formaldehyde resins, as well as polycarbonates, will be performed. The synthesized polymers will be characterized and their properties compared to properties of commercial polymers.

The project involves the development of a kinetic modeling methodology based on the mean-field microkinetics model. The large amount of data obtained will be essential for microkinetic modeling and the establishment of correlations between lignin structure, operating conditions, and product quality. A set of model-determined optimal process parameters will be verified by validation experiments. The relationship between the parameters is essential to achieve biorefinery flexibility, which is a sensible approach due to the fluctuating lignin composition.