Stepwise nitrogen-rich pyrolysis to regulate bio-oil fraction enrichment and nitrogen migration

The paper proposed an Ar/NH 3 -mediated stepwise pyrolysis strategy to regulate the component enrichment and nitrogen migration behavior of cellulose, lignin, and their mixtures during pyrolysis. There were complementary richness curves for cellulose and lignin single-component derivatives, facilitating the separation of two component derivatives. Cellulose derivatives were mainly released at 300 °C, while the pyrazoles and nitriles derived from lignin reached an enrichment of nearly 100% in the first and fourth stages, respectively. The promoting effect of interactions between the two components on product enrichment was more remarkable at 300 °C. Notably, both NH 3 and inter-component interactions jointly suppressed the release of embedded nitrogen. The comprehensive comparison revealed that cellulose was superior to lignin in deoxygenation and nitrogen doping, but nitrogen migration and transformation in the mixture were mainly determined by lignin. The paper opens up new ways for biomass components to be selectively utilized and bio-based nitrogenous chemicals to be directionally prepared.