Quantitative reliability of aromaticity and related measurements on coals by 13C n.m.r. A debate

Snape, Colin E.; Axelson, David E.; Botto, Robert E.; Delpuech, Jean‐Jacques; Tékély, Piotr; Gerstein, B. C.; Pruski, Marek; Maciel, Gary E.; Wilson, Michael

doi:10.1016/0016-2361(89)90142-7

Cited by 163 publications

(78 citation statements)

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“…The wide application of 13 C cross polarization magic angle spinning (CP/MAS) technique has significantly promoted our knowledge on coal chemical structures [40][41][42][43][44][45][46][47][48]. Spectral-editing and peak-fitting techniques have been well established to identify specific functional groups from the spectra [49][50][51][52], and the high-resolution NMR methods allow for the measurement of the relative abundance of aromatic, aliphatic, phenolic, and carboxylic carbons [53,54].…”

Section: Introductionmentioning

confidence: 99%

13C-NMR Study on Structure Evolution Characteristics of High-Organic-Sulfur Coals from Typical Chinese Areas

Wei

Tang

2018

Minerals

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Abstract:The structure evolution characteristics of high-organic-sulfur (HOS) coals with a wide range of ranks from typical Chinese areas were investigated using 13 C-CP/MAS NMR. The results indicate that the structure parameters that are relevant to coal rank include CH 3 carbon (f al *), quaternary carbon, CH/CH 2 carbon + quaternary carbon (f al H ), aliphatic carbon (f al C ), protonated aromatic carbon (f a H ), protonated aromatic carbon + aromatic bridgehead carbon (f a H+B ), aromaticity (f a CP ), and aromatic carbon (f ar C ). The coal structure changed dramatically in the first two coalification jumps, especially the first one. A large number of aromatic structures condensed, and aliphatic structures rapidly developed at the initial stage of bituminous coal accompanied by remarkable decarboxylation. Compared to ordinary coals, the structure evolution characteristics of HOS coals manifest in three ways: First, the aromatic CH 3 carbon, alkylated aromatic carbon (f a S ), aromatic bridgehead carbon (f a B ), and phenolic ether (f a P ) are barely relevant to rank, and abundant organic sulfur has an impact on the normal evolution process of coal. Second, the average aromatic cluster sizes of some super-high-organic-sulfur (SHOS) coals are not large, and the extensive development of cross bonds and/or bridged bonds form closer connections among the aromatic fringes. Moreover, sulfur-containing functional groups are probably significant components in these linkages. Third, a considerable portion of "oxygen-containing functional groups" in SHOS coals determined by 13 C-NMR are actually sulfur-containing groups, which results in the anomaly that the oxygen-containing structures increase with coal rank.

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Section: Introductionmentioning

confidence: 99%

13C-NMR Study on Structure Evolution Characteristics of High-Organic-Sulfur Coals from Typical Chinese Areas

Wei

Tang

2018

Minerals

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“…2 is less reliable, since the saturation method becomes more difficult to implement for T1 < 1×10 -4 s. Nevertheless, an important outcome from the 1 H T1 analyses is that upon annealing, an increasingly large fraction of protons (up to over 90% at the higher annealing temperatures) are characterized by a fast-relaxation mechanism. 13 C NMR signal intensities can also be adversely affected by large paramagnetic interactions [64]. For instance, Cho et al [32] have reported signal losses of about 50% due to high paramagnetic content for a variety of sputtered a-C:H samples.…”

Section: H Nmrmentioning

confidence: 99%

Solid state magnetic resonance investigation of the thermally-induced structural evolution of silicon oxide-doped hydrogenated amorphous carbon

Peng

Sergiienko

Mangolini

et al. 2016

Carbon

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“…Carbon nuclei, which are not in close proximity of protons may not undergo cross polarisation and therefore could not Ž . be 'seen' in a CP experiment by the NMR technique Snape et al, 1989 . For samples that contain significant amounts of carbon isolated from protons with a highly aromatic structure, CPMAS 13 C NMR may not give quantitative data Ž .…”

Section: Nmr Spectramentioning

confidence: 99%

Types and chemical composition of organic matter in reforested lignite-rich mine soils

et al. 1998

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Quantitative reliability of aromaticity and related measurements on coals by 13C n.m.r. A debate

Cited by 163 publications

References 1 publication

13C-NMR Study on Structure Evolution Characteristics of High-Organic-Sulfur Coals from Typical Chinese Areas

13C-NMR Study on Structure Evolution Characteristics of High-Organic-Sulfur Coals from Typical Chinese Areas

Solid state magnetic resonance investigation of the thermally-induced structural evolution of silicon oxide-doped hydrogenated amorphous carbon

Types and chemical composition of organic matter in reforested lignite-rich mine soils

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