Insights into the nitrogen-rich pyrolysis of cellulose in the presence of alkali and alkaline earth metals: Structural transformation of target products

Here, cellulose loaded with Ca and K was subjected to nitrogen-rich pyrolysis to investigate how alkali and alkaline earth metals affected its properties and the structural transformation of target products, especially the nitrogen transformation mechanism. Ca significantly reduced the activation energy of nitrogen-rich pyrolysis. The effect of Ca on the component distribution of bio-oil was significantly stronger than that of K. At Ca-0.5, the bio-oil had the highest content of nitrogen-containing compounds (77.98%), and the content of nitrogenous heterocyclic compounds (37.98%) was significantly higher than that of Ca-K-0 (27.75%). Ca and K promoted the production of pyridines. K acted on pyrroles and pyrazoles , while Ca acted on pyrazines . As Ca and K increased, both nitrogen-containing functional groups and nitrogen were enriched in biochar. Ca enhanced the H/C value of biochar and accelerated the conversion of char-N to tar-N. K tended to produce nitrogen-rich biochar with higher graphitization degree and stability.