Green chemicals from Lignin

Figure 1: Example for the molecular structure of lignin

Coworkers: Dr. Sasa Bjelic, Dmitrii Sharkov

In the context of "green" chemical production this project is dealing with lignins as a renewable resource for phenolic compounds. Lignin is a polyphenolic bio-polymer that makes up 20 % of dry wood biomass. Since lignin is produced in large scale in the pulp and paper industry as a byproduct with no further use - beside being a low quality fuel for heating - there is a large interest in the derivatisation of lignin to value-added chemicals. The majority of the research concerning lignin concentrates on the depolymerisation of lignin to phenolic compounds using different techniques like solvolysis or pyrolysis. However, these investigations consist mainly of simple try and error experiments including little fundamental research. The depolymerisation process itself is treated like a black box.

Figure 2: Setup for the EPR experiments (x-Band)
This project, on the contrary, tries to enlighten that depolymerarisation black box using state of the art analytic tools - thus providing essential basic knowledge on the reactivity of lignins, especially concerning the role of radicals in the depolymerisation process. The key to analyzing and therefore understanding the radicals behaviour in lignin lies in the use of EPR-technology, because With this special spectroscopic method radicals can be observed and characterised. This information is combined with the results of a variety of other analytical methods (NMR, IR, SEC, UV-Vis etc.) to enable a fundamental understanding and knowledge of the depolymerisation process of lignins. The longterm goal of this project is to use this knowledge to improve existing and to develop new lignin-depolymerisation techniques, eventually leading to high-value phenolic compounds from biomass and in consequence going one step further on the way towards green and sustainable chemistry.