Lignin Conversion to Low-Molecular-Weight Aromatics via an Aerobic Oxidation-Hydrolysis Sequence: Comparison of Different Lignin Sources

Diverse lignin samples have been subjected to a catalytic aerobic oxidation process, followed by formic-acid-induced hydrolytic depolymerization. The yield of monomeric aromatic compounds varies depending on the lignin plant source and pretreatment method. The best results are obtained from poplar lignin isolated via a acidolysis pretreatment method, which gives 42 wt% yield of low-molecular-weight aromatics. Use of other pretreatment methods and/or use of maple and maize lignins afford yields of aromatics ranging from 3 to 31 wt%. These results establish useful references for the development of improved oxidation/depolymerization protocols.