Conversion of Lignin to Nitrogenous Chemicals and Functional Materials

Lignin has long been regarded as waste, readily separated and discarded from the pulp and paper industry. However, as the most abundant aromatic renewable biopolymer in nature, lignin can replace petroleum resources to prepare chemicals containing benzene rings. Therefore, the high-value transformation of lignin has attracted the interest of both academia and industry. Nitrogen-containing compounds and functionalized materials are a class of compounds that have wide applications in chemistry, materials science, energy storage, and other fields. Converting lignin into nitrogenous chemicals and materials is a high-value utilization pathway. Currently, there is a large amount of literature exploring the conversion of lignin. However, a comprehensive review of the transformation of lignin to nitrogenous compounds is lacking. The research progress of lignin conversion to nitrogenous chemicals and functional materials is reviewed in this article. This article provides an overview of the chemical structure and types of industrial lignin, methods of lignin modification, as well as nitrogen-containing chemicals and functional materials prepared from various types of lignin, including their applications in wastewater treatment, slow-release fertilizer, adhesive, coating, and biomedical fields. In addition, the challenges and limitations of nitrogenous lignin-based materials encountered during the development of applications are also discussed. It is believed that this review will act as a key reference and inspiration for researchers in the biomass and material field.