Electrochemical valorization of lignin

Abstract

In pulp and paper mills, the main goal is to obtain cellulose; however, there is a secondary major product, considered a waste in this context, which goes unnoticed and has (so far) poor utility, aside from its use as fuel: lignin. This biopolymer, with complex structure, has great potential to obtain a wide range of aromatic compounds. In this project, different topics like the composition of lignin, its properties and the products into which it can be transformed will be addressed, with focus on the electrochemical conversion processes. This work, based on a comprehensive literature analysis, aims to gather several relevant articles from various scientific online databases, to accumulate a substantial amount of information emphasizing those sources that describe the performance of oxidative valorization processes. The goal is to find out which are currently the optimal reaction conditions and the ratio in which the desired products are obtained. Therefore, the project begins with an introduction that provides a brief overview of lignin, the different electrochemical oxidation processes that stand out from the rest, and the most relevant degradation products. Next, the methodology section, outlines the methodology that has been employed, the keywords that served to carry out the searches, and a brief comment on some of the obtained results. After detailing the approach followed, the results are presented in separate sections with different categories and conditions, using tables and figures to describe the results that have been compiled. Finally, by combining the knowledge gained during the degree (mainly related to Organic Chemistry and Physical Chemistry) with the findings, achieving sound conclusions that help to understand how this process is carried out and the potential future applications to optimize the obtention of the main valuable compounds. It will be shown that the degradation of lignin into aromatic products is an issue of relevance for the near future, as it may open the door to the production of organic compounds from a sustainable source and substantially reduce their dependence on petroleumbased origins.