NOx and N2O precursors (NH3 and HCN) from biomass pyrolysis: interaction between amino acid and mineral matter

Mineral matter in biomass influences nitrogen chemistry during pyrolysis. Amino acids, selected as the model compound in biomass, were pyrolyzed with the major mineral matters in biomass (potassium, calcium and iron) at 800 °C to investigate the effect of mineral matter on the distribution of N-containing species from amino acid pyrolysis. HCN and NH3 were detected online with a Fourier transform infrared (FT-IR) spectrometer. The extent of interaction between amino acid and the mineral matter was determined by comparing the yields of HCN and NH3 from pyrolysis of amino acids with mineral matters with those from amino acid pyrolysis under the same condition. The results indicate that yields of HCN and NH3 and nitrogen conversion pathway from amino acid pyrolysis are influenced by the mineral matter. Mineral matter has catalytic effects on the primary decomposition reaction pathway of amino acid as well as the secondary cracking pathway of 2,5-piperazinedione. For amino acids with reactive side chains, the mineral matter also has catalytic effects on thermal cracking of nitrogen-containing char.