Unravelling Electrochemical Lignin Depolymerization

Lignin valorisation via electrochemical depolymerization is a promising approach for commercial application due to its moderate reaction conditions. However, there is no available kinetics model for this reaction. Conventional reaction kinetics equations are inadequate when used for lignin degradation because of the limited kinetics information with respect the reaction mechanism. We suggest to use population balance equations to predict the evolution of molecular weight distribution of lignin with time. Solving the low molecular weight (MW) population balance equations is carried out discretely whereas a continuous solution was implemented for the high MW. Additionally, the model accounts for a recombination reaction for the depolymerized species. The model is capable of predicting the molecular weight distribution of lignin as a function of electrochemical processing time. New experimental results are used to extract kinetics constants for different kraft lignin samples.