Preparation of nitrogen-containing chemicals from lignocellulosic biomass and nitrogen-rich organic solid waste by pyrolysis: Characteristics, reaction mechanisms, and feedstock interactions

Nitrogen-containing chemicals (e.g., pyrroles, indoles, pyridines, and their derivatives) are platform compounds for the synthesis of agricultural chemicals and drugs. The production of high-value nitrogen-containing chemicals from biomass has significant potential to reduce energy consumption and carbon emissions. The fundamental concepts, reaction mechanisms, and regulatory mechanisms in the production steps of nitrogen-containing compounds (NCCs) still lack in-depth and systematic discussion. This paper focuses on the production processes of NCCs derived from lignocellulosic biomass and nitrogen-rich organic solid waste. It summarizes and categorizes the types of raw materials used and explores common pretreatment methods and their operating principles. From the perspective of molecular structure evolution, it explains the reaction pathways for modulating precursors of NCCs, detailing the formation processes and regulatory mechanisms of isotropic and intermediate phase products. It is evident that nitrogen in NCCs is enriched through the migration and transformation of endogenous and exogenous nitrogen in various forms. The optimal pyrolysis temperature for obtaining nitrogen-rich bio-oil is between 400–650 °C. Co-pyrolysis and catalytic pyrolysis are the most effective methods for utilizing various forms of nitrogen to produce valuable NCCs, with selectivity exceeding 50 %. Overall, this review comprehensively summarizes the compositional features of lignocellulosic biomass and nitrogen-rich substances, the conversion pathways for nitrogen-rich pyrolysis, and the formation routes of NCCs. Finally, the technical challenges and future development directions for preparing NCCs are proposed and discussed.