Investigation on compositional and structural features of Xianfeng lignite through sequential thermal dissolution

Rapid Comm Mass Spectrometry

Xia

et al. 2020

Rationale Gas chromatography/mass spectrometry (GC/MS) and high‐performance liquid chromatography/time‐of‐flight mass spectrometry (HPLC/TOF‐MS) were used to separate and reveal the molecular characteristics of organic matter in low‐rank coals. Methods Six soluble portions (SPs) were obtained by sequential thermal dissolution (TD) of two low‐rank coals in the order of cyclohexane, acetone and methanol solvents at 300°C. Organic matter with different molecular characteristics were enriched in eachTD extract, which was further separated and analyzed by GC/MS and HPLC/TOF‐MS using an electrospray ionization source in positive mode to obtain a comprehensive understanding of the structural composition of coals. Results Low polarity compounds like alkanes and arenes have a better solubility in cyclohexane. Phorone has the highest relative abundance in the acetone SPs, and the main compounds detected in the methanol SPs are alcohols and phenols. According to the data from HPLC/TOF‐MS, most of the oxygen atoms are in the form of carbonyl and alkoxy groups. The nitrogen‐containing compounds in SPs are mainly saturated aliphatic amines and pyridines. The sulfur‐containing compounds mainly exist in the form of thioalkanes and thiophenes. Conclusions Non‐destructive methods were used to obtain soluble matter from coals, and different chromatographic and mass spectrometric techniques were used to separate and analyze the organic matter in coals. Detailed molecular structural information was obtained for the efficient and clean utilization of low‐rank coals.

Section: Resultsmentioning

confidence: 99%

Sequential thermal dissolution of two low‐rank coals and characterization of their structures by high‐performance liquid chromatography/time‐of‐flight mass spectrometry and gas chromatography/mass spectrometry

Cao

Rapid Comm Mass Spectrometry

Xia

et al. 2020

“…As an inherent and non‐polar solvent, cyclohexane inclines to thermally extract compounds from coal without breaking chemical bonds . In the cyclohexane filtrate, phenols and ketones OCCs are the dominant products with relative abundance of 53.4% and 21.4%, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…There is no such broad distribution of carbon number in Figs. 6b and 6c, therefore the extracted species with high molecular weight in Figure S6a have long alkyl chains and the chains are not broken during TD of cyclohexane due to its stable chemical property . Although ESI‐TOF‐MS has extended the identification of compounds with higher molecular weight not detected by GC/MS, species with over 2 aromatic ring (DBE > 7) still have low relative abundances of 6.1%, 1.6% and 3.8 for the three filtrates.…”

Section: Resultsmentioning

confidence: 99%

Molecular Characteristics of Shenfu Coal Characterized by Mass Spectrometers with Three Ion Sources

Zhao

et al. 2018

ChemistrySelect

Self Cite

A coal sample was extracted at 300 oC sequentially with cyclohexane, acetone and methanol to obtain three filtrates. Mass spectrometers coupled with various commercial ion sources such as electron ionization (EI), electrospray ionization (ESI) or atmospheric pressure photoionization (APPI) were used to acquire a full view of molecular information for the coal and build up the analytical strategy for aromatics. Phenols, furans and ketones were the most abundant products in the filtrates of cyclohexane, acetone and methanol, respectively, which were obtained by mass spectrometer with EI source. ESI well ionized compounds with high polarity and high molecular weight (900 Da), but not for aromatics with ring number over 2. APPI enhanced the ionization efficiency for compounds with both high molecular weight and high aromatic ring size, which is the best one for the analysis of aromatics.

“…Identifying chemicals in the extracts is important for understanding coal structures and separating value‐added chemicals from coals. Sequential low‐temperature extraction and/or thermal dissolution, with the same solvents at different temperatures (Ding et al, ; Wang et al, ) or with different solvents at same temperature (Li et al, ; Shi et al, ; Ding et al, ), can facilitate the release of hydrocarbons and OCCs from coals and their identification with GC/MS. Some typical series of hydrocarbons and OCCs detected by GC/MS in the extracts from coal extraction and thermal dissolution are listed in Table .…”

Section: Small‐molecular Chemicals In Cdls Identified By Gc/msmentioning

confidence: 99%

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

Liu

Mass Spectrometry Reviews

Wei

et al. 2016

Self Cite

Coal-derived liquids (CDLs) are primarily generated from pyrolysis, carbonization, gasification, direct liquefaction, low-temperature extraction, thermal dissolution, and mild oxidation. CDLs are important feedstocks for producing value-added chemicals and clean liquid fuels as well as high performance carbon materials. Accordingly, the compositional characterization of chemicals in CDLs at the molecular level with advanced analytical techniques is significant for the efficient utilization of CDLs. Although reviews on advancements have been rarely reported, great progress has been achieved in this area by using gas chromatography/mass spectrometry (GC/MS), two-dimensional GC-time of flight mass spectrometry (GC × GC-TOFMS), and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). This review focuses on characterizing hydrocarbon, oxygen-containing, nitrogen-containing, sulfur-containing, and halogen-containing chemicals in various CDLs with these three mass spectrometry techniques. Small molecular (< 500 u), volatile and semi-volatile, and less polar chemicals in CDLs have been identified with GC/MS and GC × GC-TOFMS. By equipped with two-dimensional GC, GC × GC-TOFMS can achieve a clearly chromatographic separation of complex chemicals in CDLs without prior fractionation, and thus can overcome the disadvantages of co-elution and serious peak overlap in GC/MS analysis, providing much more compositional information. With ultrahigh resolving power and mass accuracy, FT-ICR MS reveals a huge number of compositionally distinct compounds assigned to various chemical classes in CDLs. It shows excellent performance in resolving and characterizing higher-molecular, less volatile, and polar chemicals that cannot be detected by GC/MS and GC × GC-TOFMS. The application of GC × GC-TOFMS and FT-ICR MS to chemical characterization of CDLs is not as prevalent as that of petroleum and largely remains to be developed in many respects. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 36:543-579, 2017.