XPS determination of the forms of nitrogen in coal pyrolysis chars

Abstract

The N 1s spectra from four pulverized Australian coals and their chars produced by pyrolysis for 2 s at 1100 °C and 1300 °C in a pressurized furnace are evaluated, with particular reference to the binding energy region above 402 eV. The spectra for the feed coals were broadly similar to those reported previously for bituminous coals, in that pyrrolic nitrogen was the dominant functional form in each case. A minor component between 403 and 404.5 eV was assigned to ammonium nitrogen in liberated mineral matter. The N 1s spectra for the chars were also broadly similar to those expected for pyrolysis under intermediate residence time conditions, in that the proportion of pyrrolic nitrogen was no more than half that for the feed coal. Intensity in the 402–404.5 eV region was more consistent with N–O species formed post‐pyrolysis than similar species formed as intermediates during pyrolysis. Copyright © 1999 John Wiley & Sons, Ltd.

Organic nitrogen chemistry during low-grade metamorphism

“…Candidates for generating the N-Q2 sub-peak at 402.7 eV (FWHM = 1.5 eV) and the N-X sub-peak at 403.6 eV (FWHM = 1.5 eV) are (i) pyridinic nitrogen atoms bonded to oxygen atoms, (ii) nitrogen substituting for carbon in condensed, partially aromatic systems (a higher nitrogen binding energy would arise both from charge transfer and hybridization; Casanovas et al, 1996), and (iii) ammonium fixed in clays ( Fig. 5; Buckley et al, 1995Buckley et al, , 1996Gong et al, 1999) where the outermost sheet is composed of oxygen anions inducing a particular local interlayer environment, in contrast to simple ammonium salts (Yu, 2007;He et al, 2007). Kerogen does not contain any silicate minerals that can host ammonium, therefore the N 1s XPS N-Q2 and N-X sub-peaks of kerogen from the meta-anthracitecontaining shale 19J cannot be caused by clay-bound NH 4 + (Fig.…”

“…5f) feature a main Lorentzian-Gaussian sub-peak N-Q2 around 402.7 eV reflecting ammonium in illite that had also been identified by X-ray diffraction (Daniels, 1992). The presented N 1s XPS evidence for an ammonium contribution to sub-peak N-Q2 is corroborated by studies of Buckley et al (1995Buckley et al ( , 1996 and Gong et al (1999). The use of demineralized kerogens in our study eliminated mineral-hosted ammonium and facilitated the deconvolution of N 1s XPS spectra in terms of the exclusive presence of organic nitrogen.…”

“…The N-X sub-peak in Fig. 5b may relate to organic R=N-O-R where nitrogen is linked to carbon (R) and to one oxygen atom (e.g., Gong et al, 1999;Xiao al., 2005).…”

Parameter setting for peak fitting method in XPS analysis of nitrogen in sewage sludge

“…The type of protein-N took the highest part among all the nitrogen containing components, and ammonium-N accounted for the largest proportion of inorganic nitrogen. According to model compound data and references [3,5,6] , the N1s spectra curve can mainly be resolved into 5 peaks Table 4. …”

Efforts to Curb NOx from Greenhouse Gases by the Application of Energy Crops and Vegetation Filters

“…The nitrogen functionalities in biochar are pyrrolic-N, pyridinic-N, quaternary-N and amines [83][84][85] and incubation tests evidenced that these stable nitrogen forms with low bioavailability [86].…”