(315d) Selective Aromatic Ring-Opening of Biorefinery Lignin Towards Dicarboxylic Acids:  Influence of Reaction Temperature and pH

Lignin is the worldâ??s only sustainable source of aromatic compounds, which has resulted in a significant quantity of research being conducted on the depolymerization of this complex biopolymer for the production of low molecular weight aromatic compounds. These aromatic products can then be further broken down via selective ring-opening to form dicarboxylic acids.

Dicarboxylic acids are a valuable class of organic compounds which are utilized in numerous commercial industries, including the production of biopolymers, pharmaceuticals, and food products. Like phenolic compounds, dicarboxylic acids are currently dependent on crude oil as a feedstock. However, lignin has the potential to act as a sustainable alternative.

This work investigates the selective production of dicarboxylic acids from several different types of lignins, via thermochemical breakdown. The treatment conditions employed a temperature range of 60 to 250 °C, and a reaction mixture pH of 4 to 13. The major products obtained in this work were oxalic, malonic and succinic acids. Yields of up to 10 wt.% oxalic acid were achieved, based on the mass of lignin treated.