Interaction evolution and N product distribution during biomass co-pyrolysis for endogenous N-doping bio-carbon

N-doping carbon material finds intriguing applications in electrochemistry, photochemistry, catalysis and adsorption scenarios. However, the conversion process of N-doping biochar from endogenous N biomass sources remains obscure. To gain deeper insights into the pyrolysis process and N element migration patterns of blended biomass feedstock, this study investigated the pyrolysis of selected biomass polymers using cellulose and chitin as representative nitrogen-free and nitrogen-containing polymers, respectively. Phenylalanine, a typical amino acid with high content in protein, was selected to investigate the influence of protein on cellulose and chitin conversion. Special attention was given to the presence and transformation patterns of N components during co-pyrolysis, with related possible co-pyrolysis mechanisms explored based on research findings. The results showed that the co-pyrolysis of phenylalanine with cellulose/chitin exhibited significant interactive effects, characterized by promotion in reaction kinetics and integration of N content in biochar, especially in the case of N-deficient cellulose. The interaction between pyrolysis products from phenylalanine and cellulose/chitin significantly changed the constituent of volatiles from pyrolysis with increased hydrocarbon content and reduced oxygenated content. And higher temperature and excess phenylalanine addition increased the variety of organic-N compounds, while amines, amides and quinolines consistently displayed high selectivity. The results provided theoretical and data references for high performance N-doping biochar production and low nitrogen emissions from natural blended biomass through thermal conversion.