DETERMINATION OF THE FATE OF NITROGEN FUNCTIONALITY IN CARBONACEOUS MATERIALS DURING PYROLYSIS AND COMBUSTION USING X-RAY-ABSORPTION NEAR-EDGE STRUCTURE SPECTROSCOPY

X-ray absorption near edge structure (XANES) was used to investigate t he fate of nitrogen functional groups in carbons derived from acridine , carbazole, and polyacrylonitrile during carbonization. Acenaphthylen e and poly(vinyldene chloride) carbons with nitrogen incorporation by ammonia treatment at elevated temperatures were also studied. In gener al, the nitrogen XANES data provided more detail than the correspondin g X-ray photoelectron spectroscopy (XPS) results and confirm the overa ll picture obtained from XPS involving the greater stability of pyridi nic and quaternary nitrogen functionalities with increasing severity o f pyrolysis. Partial gasification of the carbons in 20% oxygen/argon p roduced a new peak or greatly increased the intensity of an existing n itrogen XANES peak at similar to 401.5 eV which was independent of the nitrogen functionality originally present in the carbon. The oxygen X ANES spectra showed that carbonyl and carboxylic acid/acid anhydride f unctionality were also present on the surface of carbons partially gas ified with oxygen. The XANES studies have also been compared with the temperature-programmed combustion and temperature programmed desorptio n studies of the carbons. The results are consistent with the presence of pyridone functionality in the partially gasified carbons. The over lap of bands may obscure the interpretation of data from X-ray absorpt ion spectroscopy, and information is required from a number of techniq ues in order to provide a more detailed view.