Characterization of Biomarkers and Structural Features of Condensed Aromatics in Xianfeng Lignite

Abstract

Xianfeng lignite (XL) was sequentially extracted under ultrasonication at room temperature with petroleum ether, carbon disulfide (CDS), methanol, acetone, and isometric CDS/acetone mixed solvent to afford extracts 1–5, respectively. The mixed solvent-inextractable portion was sequentially extracted with cyclohexane, benzene, 1-methylnaphthalene, methanol, and ethanol at 320 °C to afford extracts 6–10, respectively. The extracts were analyzed with a gas chromatography/mass spectrometer (GC/MS) to characterize biomarkers in XL. The biomarkers were significantly enriched in extracts 1 and 6. They can be classified into a series of n-alkanes, isoprenoid alkanes, terpenoids, n-alkenes, methyl alkanones, n-alkylbenzenes, n-alkyltoluenes, and n-alkyl-p-xylenes. The biomarker distributions provided important information on the main origin of organic matter in XL. Related mechanisms for the formation of biomarkers during coalification were discussed. The residue from sequential thermal extraction was subjected to ruthenium-ion-catalyzed oxidation along with subsequent product analyses with GC/MS and direct analysis in a real-time ionization source coupled to a time-of-flight mass spectrometer (DARTIS/TOFMS) to understand its structural features. The results show that the residue is rich in condensed aromatics (CAs) and methyl is the dominant alkyl side chain on aromatic rings. The aromatic rings in the residue are mainly connected by −(CH2)3– and −CHCH3(CH2)2–. DARTIS/TOFMS analysis suggests that CAs with alkyl-substituted biphenyl and alkyl-substituted phenylbiphenyl skeletons also exist in the residue. This investigation provides an effective approach for understanding biomarkers and the structural features of the macromolecular network in XL.

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

“…Obtaining detailed information on ONCs is difficult due to their low content in coals. Gas chromatography/ mass spectrometry (GC/MS) has been successfully applied in identification of some soluble species from coals [12][13][14][15][16][17][18][19], but detecting less volatile and/or thermally labile species is difficult using this technology. In addition, GC/MS analysis is easily affected by complex matrix and there are only limited standard libraries for the identification of detected species.…”

Characterization of Oxygen-Containing Species in Methanolysis Products of the Extraction Residue from Xianfeng Lignite with Negative-Ion Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

“…The ER was derived from XL via ultrasonic extraction, as reported in our recent investigation. 44 Table 1 lists the proximate and ultimate analyses of XL and the ER. NaOH, hydrochloric acid (HCC), petroleum ether (PE), carbon disulfide (CDS), acetone, and diethyl ether (DEE) used in the experiments are analytical reagents, and all of the organic solvents were distilled prior to use.…”

Application of mass spectrometry in the characterization of chemicals in coal‐derived liquids

“…GC/MS is one of effective analytical techniques for characterizing the small molecules in extracts from low‐temperature extraction (Liu et al, , , ; Zong et al, ; Shi et al, ; Cong et al, ,b; Mahat, Rodgers, & Basile, ; Ding et al, ) or thermal dissolution (Chen et al, ; Lu et al, ; Liu et al, ; Zhou et al, ; Adesanwo et al, ; Wang et al, , 2015d; Ding et al, ; Zhao et al, ) of coals with various solvents. Identifying chemicals in the extracts is important for understanding coal structures and separating value‐added chemicals from coals.…”