Selective activation of C C bonds in lignin model compounds and lignin for production of value-added chemicals

Lignin is a rich renewable aromatic resource that can produce high-value-added chemicals. Lignin is regarded as one of the three major components of lignocellulosic biomass, which is composed of phenylpropane units connected by CO bond and CC bond. The cleavage of two chemical bonds is the main catalytic pathway in the production of chemicals and fuels from lignin. Although the cleavage of CO converts lignin into valuable aromatic compounds and renewable carbon sources, selective depolymerization for CC bonds is an important method to increase the yield of aromatic monomers. Therefore, in this review, we summarized the latest research trends on CC bond selective cleavage in lignin and lignin model compounds, focusing on various catalytic systems, including hydrogenolysis, oxidate, photocatalysis, and electrocatalysis. By analyzing the current status of CC bond breakage, the core issues and challenges related to this process and the expectations for future research were emphasized.