(434c) Selectively Cleaving Carbon?Carbon Interunit Linkages in Lignins to Boost Monomer Production

In recent years tremendous efforts have been made to valorize lignin. One of the extensively-studied pathways is to depolymerize lignin biopolymer into monomers. Typically, monomer yields of 10-50% can be obtained by cleaving beta-O-4 interunit carbon─oxygen linkages present in various lignins. Further improvement of monomer yields is limited by interunit carbon─carbon linkages formed during lignin biosynthesis and biomass pretreatment. To fully valorize lignin, it is essential to find a proper way to cleave these carbon─carbon linkages. In this presentation, we will report our recent work on screening catalyst for disrupting interunit carbon─carbon linkages in lignins. We found a series of inexpensive non-noble metal catalysts able to selectively cleave various interunit carbon─carbon linkages in dimeric lignin models at moderate temperatures. With these catalysts, improved monomer yields were obtained from condensed technical lignins by cleaving not only interunit carbon─oxygen but also interunit carbon─carbon linkages.