Effects of Coal Structures on Denitrogenation during Flash Pyrolysis

Yallourn, Taiheiyo, South Banko, Miike, and Hunter Valley coals were pyrolyzed using a Curie-point pyrolyzer at 500−1040 °C. Product distributions were determined by GC-TCD and GC-FTD, and N 2 evolved in the gas phase was analyzed using a quadrupole mass spectrometer. Samples were also prepared by mildly oxidizing Yallourn coal and hydrogenating the resulting ethanol soluble over a Ru/Al 2 O 3 catalyst. Quinoline and hydrogenated quinolines were also used as models in order to better understand the role of the heterocyclic structure in denitrogenation during pyrolysis. More than 90 mol % of the nitrogen atoms in the coals remained in the char and tar as a result of the pyrolysis of the raw coals. However, the heterocyclic structures of the raw Yallourn coal were partially changed by hydrogenation over a Ru/Al 2 O 3 catalyst, and this alteration enhanced the cleavage of those structures during pyrolysis, decreased the nitrogen content of the char, and increased the yield of nitrogen compounds in the gas phase.