Comparison of fractions of pyridine extract and solvent-refined coal from Illinois No. 6 coal

Mayo, Frank R.; Kirshen, N.

doi:10.1016/0016-2361(78)90054-6

Cited by 24 publications

(4 citation statements)

References 2 publications

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“…Trace metal analyses and detection in an organic phase offer several advantages: (1) fewer sample handling techniques, (2) no opportunity for the introduction of trace metal impurities in an ashing step, (3) of organically bound metals, and (4) possible metal speciation data when coupled with high-performance liquid chromatography (HPLC). Pyridine is a particularly good solvent for most synfuel materials (8). In addition, we (9) have shown pyridine to be an acceptable mobile phase for size exclusion chromatography (SEC) of synfuels.…”

Section: Literature Citedmentioning

confidence: 99%

Size exclusion chromatography of organically bound metals and coal-derived materials with inductively coupled plasma atomic emission spectrometric detection

Hausler¹,

Taylor²

1981

Anal. Chem.

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Section: Literature Citedmentioning

confidence: 99%

Size exclusion chromatography of organically bound metals and coal-derived materials with inductively coupled plasma atomic emission spectrometric detection

Hausler¹,

Taylor²

1981

Anal. Chem.

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“…This work has been severely critikized (306)(307)(308)(309)(310)(311)., but the debate over polyamantane structures in coals continues (see Reference 133). There is some additional evidence to support the presence of.extended cycloalkane structures in coals (312)(313)(314)(315)(316), al.though not to the extent implied 'by earlier studies (160,299). Evidence from other recent oxidations of'coal, employing sodium dichromate (153,309,310) , and measurements of coals by solid-state 13.c and ' H NMR (31, 269also'the following section) .still suggest that coals do contain aromatic structures which increase in condensation with increasing carbon content.…”

Section: Hydrogen Aromaticity In Coalsmentioning

confidence: 97%

Study of hydrogen in coals, polymers, oxides, and muscle water by nuclear magnetic resonance; extension of solid-state high-resolution techniques. [Hydrogen molybdenum bronze]

Ryan¹

1981

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range of isotropic shifts typical of protons, about 10 ppm compared with 200 ppm for carbon or fluorine, resolution requirements for separation of individual.-lines were generally found to be more severe in these.systems. CHAPTER 3. ISOTROPIC PROTON .NMR.SPECTRA OF RIGID, RANDOMLY ORIENTED SOLIDS * ". Figure 19. The effect of offset on the MREV-8 pulse CRAMPS spectrum of 4,4'-dimethylbenzophenone, at tc=27,6 psec

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“…As an effective method, solvent extraction is now widely used in the study of the composition and structural characteristics of coal. − At the same time, coal pyrolysis is one of the important steps of coal utilization, but the coal pyrolysis process is affected by many factors, including the influence of small molecular components, the cracking of macromolecular component bonds, and the synergy between them. In the research of small molecules, organic solvent extraction is an effective method. , What is more, the solvent extraction is one of the most effective ways to study the element-transfer paths during the coal modification. , The radical concentration of coal changed significantly during the extraction process − due to the combined effects of the physical actions and bond breaking. Diverse extraction reagents have been used based on the existing research, including single-solvent, polar solvent, and high-boiling-solvent extractions.…”

Section: Introductionmentioning

confidence: 99%

“…In the research of small molecules, organic solvent extraction is an effective method. 9,10 What is more, the solvent extraction is one of the most effective ways to study the element-transfer paths during the coal modification. 11,12 The radical concentration of coal changed significantly during the extraction process 13−15 due to the combined effects of the physical actions and bond breaking.…”

Section: Introductionmentioning

confidence: 99%

Solvent Extraction of Superfine Pulverized Coal. Part 2. Free-Radical Characteristics

2021

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To better explore coal macromolecular models from the extraction aspects, the behaviors of free radicals during the solvent extraction of superfine pulverized coal were studied. The electron paramagnetic resonance (EPR) method was employed to characterize the extracts and extraction residues (ERs) from the pyridine (PY) and tetrahydrofuran (THF) extraction processes. The EPR parameters of different paramagnetic centers were analyzed through the peak deconvolution, and the detailed extraction mechanisms were discussed. The result suggests that the particle size and polarity of the reagent have the combined influences on the free-radical characteristics during the extraction process. Compared to the raw coals (rcs), the free-radical concentrations of the ER show a similar level, while these are 1 order of magnitude lower for the extracts (about 6 to 9% of rcs). In addition, PY with higher polarity is prone to attack the non-covalent interactions like hydrogen bonds, which can extract more abundant molecule components connected by charge-transfer forces, resulting in 35.42% higher spin concentrations compared to the THF extracts. On the other hand, THF with an affinity with oxygen-containing groups can loosen the coal structure, which extracts more stable oxygenated compounds. In addition, THF can effectively target the π–π interactions, and the paramagnetic centers on these aromatic clusters can be better preserved due to the steric hindrance effect. The study sheds light on better elucidation of coal macromolecular structures, which provides support on better understanding coal pyrolysis and liquefaction behaviors.

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Comparison of fractions of pyridine extract and solvent-refined coal from Illinois No. 6 coal

Cited by 24 publications

References 2 publications

Size exclusion chromatography of organically bound metals and coal-derived materials with inductively coupled plasma atomic emission spectrometric detection

Size exclusion chromatography of organically bound metals and coal-derived materials with inductively coupled plasma atomic emission spectrometric detection

Study of hydrogen in coals, polymers, oxides, and muscle water by nuclear magnetic resonance; extension of solid-state high-resolution techniques. [Hydrogen molybdenum bronze]

Solvent Extraction of Superfine Pulverized Coal. Part 2. Free-Radical Characteristics

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