THE FATE OF NITROGEN FUNCTIONALITIES IN COAL DURING PYROLYSIS AND COMBUSTION

X-ray photoelectron spectroscopy (XPS) was used to investigate the nitrogen functional forms present in several coals and their chars. The chars were prepared under different severity conditions to capture transformations in nitrogen functionality occurring during pyrolysis. It has been demonstrated that nitrogen present in coal in pyrrolic forms is converted into pyridinic functionalities upon heat treatment. Nitrogen functionality was related to the conversion of fuel-bound nitrogen to NO(x) and N2O in fluidized-bed combustion and in low-temperature char oxidation. No evidence of a strong dependence on nitrogen functionality was found for char-N partition between NO and N2O. Under the experimental conditions used in this work, pyrrolic and pyridinic functionalities were found to release NO and N2O in the same proportion of about 5:1.