Research: Project 5

Biomimetic cleavage of lignin for the production of value-added biofuels and chemicals

Lignin is an energy- and carbon-rich aromatic polymer found in plant cell walls. Historically treated as a waste by-product of the pulp and paper industry, it has recently gained attention as a possible bio-substitute for petroleum. However, lignin depolymerization is energy intensive and costly due to the difficulty of cleaving the linkages that bind the aromatic propylphenol subunits together. In addition, oxidative depolymerization methods decrease the energy density of the cleavage products and often lead to undesired formation of new covalent crosslinks. For both of these reasons, interest has grown in strategies that depolymerize lignin based on reduction rather than oxidation.

As part of the DOE-funded Great Lakes Bioenergy Research Center, we are focusing on reductive cleavage of lignin that mimics the chemistry of several successful lignin degrading bacterial enzymes. In particular, we have developed a mild strategy that uses the nucleophilic and reductive properties of thiols to cleave keto aryl ether bonds, an important linkage in the lignin polymer backbone. Current work in our lab seeks to expand the scope of these thiol redox carriers, apply it to an electrochemical system to increase efficiency, and explore other biological processes as a model to valorize polymeric lignin.