CHAR-NITROGEN FUNCTIONALITY AND INTERACTIONS BETWEEN THE NITROGEN ANDIRON IN THE IRON-CATALYZED CONVERSION PROCESS OF COAL NITROGEN TO N-2

Iron catalysts precipitated on brown and bituminous coals promote conv ersion reactions of coal nitrogen to Nz during pyrolysis at 900 degree s C, and the NS evolved from the brown coal arises mainly from char ni trogen(char-N). The present study, thus, focuses on clarifying the eff ect of the iron on char-N functionality and elucidating interactions b etween the two mainly with X-ray photoelectron spectroscopy(XPS). The N Is spectra of brown coal chars revealed that the catalyst lowered th e ratio of pyrrolic-N/pyridinic-N irrespective of the depth of the cha r, indicating the preferential formation of Nz from pyrrolic-N. In the Fe 2p and N Is XPS spectra of the Fe-bearing chars, Ar sputtering rem oved surface iron oxides to expose the metallic phase and concurrently increased the proportion of pyridinic-N with the corresponding decrea se in quaternary-N. It is suggested that there are strong interactions between the iron and char-N even in the process of N-2 formation. Iro n particles were more finely dispersed on the brown coal char and in c loser contact with it, which accounts for higher conversion of char-N to Na. A schematic mechanism for this conversion process is discussed in terms of solid-solid reactions of metallic iron and char-N.