Characterization of organonitrogen species in Xianfeng lignite by sequential extraction and ruthenium ion-catalyzed oxidation

Insight into the structural features of Zhaotong lignite using multiple techniques

“…XPS has been used to characterize the surface elemental compositions of coals and their residues [8,11,34]. For XPS analysis, the C 1s peak position was set at 284.8 eV and used as reference to position other peaks.…”

“…Coals are too complex to be elaboratively characterized. It is common to understand original structural information on coals with direct characterization tools, such as solid-state 13 C nuclear magnetic resonance (NMR) [6][7][8], Fourier transform infrared (FTIR) spectrometer [9,10], and X-ray photoelectron spectrometer (XPS) [11][12][13]. http Analyses with such tools greatly facilitate the understanding of carbon skeleton structures and functional groups along with oxygen, nitrogen, and sulfur forms in coals.…”

Identification of basic nitrogen compounds in ethanol-soluble portion from Zhaotong lignite ethanolysis by positive-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

“…Although arylamines are also present as BNCs and were identified in some coal-derived liquids [17,37], most of them could not be detected in positive-ion mode due to their weaker basicity. For instance, 1-aminoanthracene cannot be ionized via protonation in positive-ion mode [38].…”

Effect of Ca2+ species with different modes of occurrence on direct liquefaction of a calcium-rich lignite

“…Iron species evolved from pyrite could rapidly transform into pyrrhotite and catalyze the hydrogen transfer reactions to enhance oil yield [6][7][8] and in contrast, char-forming reactions catalyzed by clay might limit the conversion of coal during liquefaction process [9]. Hence, demineralized treatment or solvent extraction has been applied to upgrade lignites for more efficient utilization and better understandings in coal structures [10][11][12][13][14]. Low-rank coals, as the preferred liquefaction feedstocks, contain significant amounts of exchangeable cations which are present in the form of carboxylic and phenic salts [15].…”