Control of the chemical structure of perhydrous coals; FTIR and Py-GC/MS investigation

Iglesias, Marı́a José; Rı́o, José C. del; Laggoun‐Défarge, Fatima; Cuesta, Marcelino; Suárez‐Ruíz, Isabel

doi:10.1016/s0165-2370(00)00209-6

Cited by 76 publications

(70 citation statements)

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“…Such knowledge could be attained through the analysis of the trapped compounds. The GC/MS analyses of the volatile fraction of the soluble fraction of the perhydrous vitrinites and their comparison with data from the molecular characterization by means of Py-GC/MS [17] show that the extractable material of these coals could at least in part be, representative of the nature of the such hydrogenated compounds present in their matrices.…”

Section: Introductionmentioning

confidence: 95%

Chemical–structural characterization of solvent and thermal extractable material from perhydrous vitrinites

Iglesias

Rı́o²,

Laggoun‐Défarge

et al. 2003

Journal of Analytical and Applied Pyrolysis

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In this work, the characterization of the non-covalently bonded compounds present in a set of perhydrous coals of different age and geographical location (Cretaceous coals: UCV and TCV and Jurassic coals: AJV, PGJV, WJVh and WJVl) was carried out by means of a combination of the analyses of the material soluble in chloroform and the thermal extract. The extract in chloroform was studied through GC/MS and NMR and the thermovaporized fraction was obtained by means of flash pyrolysis at the Curie temperature of 350 °C and quantified by online GC-MS. The results obtained for the Cretaceous coals confirm that the substances responsible for the hydrogenation are those covalently bonded to the vitrinite network as a result of the modifications undergone by the botanical precursors. Despite the striking similarity in the global characteristics of these two coals (TCV and UCV) significant differences between the material non-covalently bonded to their coal matrices were found. These differences are attributed to the type of resins present in the coals and/or to their different degree of evolution. With respect to the Jurassic coals, the present study allows the process by which the hydrogenated substances were assimilated into their structure to be established. The characterization of the assimilated substances in the WJVl coal reveals an unexpectedly high incorporation of alkanes given the humic origin of this sample. From these results the assimilation of hydrogen-rich substances from the decomposition of the organic remains in the sedimentary environment in which WJVl precursor were deposited, is proposed. The incorporation of products derived from the primary decomposition of organic material is not evident for the WJVh and AJV coals. The substances assimilated into the coal matrices show a higher aromaticity, the aromatic structures of WJVh being more condensed than those found in AJV. The compositional differences between them probably arise from the different source of the hydrogen-rich material. In the case of AJV coal the source was the adsorption of hydrocarbons generated and migrated from the Pliensbachian source-rocks whereas in WJVh, assimilated compounds come from the material generated by the thermal transformation (coalification) of the adjacent organic rocks of similar age. Finally, PGJV shows two types of non-covalently bonded compounds. Solvent extractable material is mainly composed of the first type of compounds, which is predominantly aliphatic in nature with a preponderance of alkanes. The second type of compounds is more aromatic and they are probably located in the close porosity of this coal. They are not accessible to chloroform but they are the most abundant in the thermal extract.

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Section: Introductionmentioning

confidence: 95%

Chemical–structural characterization of solvent and thermal extractable material from perhydrous vitrinites

Iglesias

Rı́o²,

Laggoun‐Défarge

et al. 2003

Journal of Analytical and Applied Pyrolysis

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“…The composition of the degradation products is mainly phenolic [9], thus explaining the lacking of the aromatic mode at 1500 cm −1 in the FTIR of the pyrolysates (Fig. 2).…”

Section: Fourier Transformed Infra Red Spectroscopy (Ftir)mentioning

confidence: 97%

“…The data of raw samples and those of pyrolysis residues at slow heating rate have been previously reported [8 and 9]. The major structural units of the perhydrous raw vitrains are simple phenols with a predominance of para-alkyl substituted derivatives [9]. The presence of such structures is reflected through the clear absorption at 1500 cm −1 and, at least in part, the predominance of the 815 cm −1 mode in the 900-700 cm −1 (out-of-plane bending modes of aromatic C-H bonds).…”

Section: Fourier Transformed Infra Red Spectroscopy (Ftir)mentioning

confidence: 99%

“…Nevertheless, the characterisation of the degradation products of our samples shows that the oxygen in the raw materials is contained mainly as phenolic groups, which are more stable. Thus, the release of oxygen is due to the release of phenol derivatives in the oils [9]. This probably leads to the 'alteration' of the suspensive medium properties.…”

Section: Influence Of Initial Compositionmentioning

confidence: 99%

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04/00051 Coking properties of perhydrous low-rank vitrains. Influence of pyrolysis conditions

2004

Fuel and Energy Abstracts

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Compositional transformations occurring during natural coalification generally lead to increased coking potential of coals characterised in the resulting cokes by large sizes of molecular orientation domains (MOD) determined through transmission electron microscopy with 002 dark field mode. In this study, two sets of perhydrous low-rank vitrains (WJV and UCV) have been pyrolysed using an open-system with two heating rates in an attempt to increase their coking potential. Results show that, despite the high potentialities of such vitrains for producing hydrocarbons, i.e. a suspensive medium efficient for their cokefaction, each of the pyrolysis methods does not lead to solid residues chemically equivalent to natural coking coals, since the cokes from these residues are always made of smaller MOD than those obtained for coking coals. For comparison, a similar characterisation, carried out on a conventional vitrain (Fouthiaux) pyrolysed in a confined-system which prevents the release of hydrocarbons, leads also to non-coking coals. The formation of such MOD is likely due to the peculiar chemical composition of the precursors and/or the pyrolysis conditions. FTIR data show that perhydrous vitrains are characterised by a low degree of condensation of aromatic units with a very small concentration of aromatic rings of large size. Thermal treatment originates depolymerisation reactions in the vitrinite network with the formation of low molecular weight products which are not efficient to form large anisotropic domains. The oxygen, present in relatively high amount in some vitrains (UCV and Fouthiaux) might also act as a crosslinking agent preventing the formation of large MOD. Furthermore, while openmedium pyrolysis leads to an important effluent release, as shown by the rapid decrease of H/C ratio, hydrocarbon effluents are conversely retained within the coal matrix in the case of confined-medium pyrolysis. However, the latter pyrolysis induces secondary cracking reactions leading to the formation of lighter products. Therefore, the enhancement of coking properties has not been totally reached by our experiments insofar as they did not lead to oxygen-poor artificially matured coals, similar to natural coking coals.

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“…Biomarkers obtained from gas chromatography and gas chromatography/mass spectrometry techniques have been found to be a powerful tool for source rocks to oil correlation (e.g., Philp, 1985a,b;Bordenave, 1993). The pyrolysis gas chromatography/mass spectrometry is another method to analyze the organic-rich rocks that provides more detailed information about the chemical composition of the organic components (e.g., Iglesias et al, 2002;Peters et al, 2005). Other bulk geochemical analyses used to characterize dispersed organic matter include total organic carbon determinations (TOC), elemental analysis (C, H, O, N, S), infrared spectroscopic analysis, nuclear magnetic resonance for characterizing the chemical structures and functional groups (e.g., Iglesias et al, 2006;Kelemen et al, 2007), electron paramagnetic resonance, and isotopic analyses (e.g., Galimov, 2006).…”

Section: Other Analysis In Organic-rich Rocks and Coalsmentioning

confidence: 99%

Organic Petrology: An Overview

Suárez-Ruiz¹

2012

Petrology - New Perspectives and Applications

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Control of the chemical structure of perhydrous coals; FTIR and Py-GC/MS investigation

Cited by 76 publications

References 51 publications

Chemical–structural characterization of solvent and thermal extractable material from perhydrous vitrinites

Chemical–structural characterization of solvent and thermal extractable material from perhydrous vitrinites

04/00051 Coking properties of perhydrous low-rank vitrains. Influence of pyrolysis conditions

Organic Petrology: An Overview

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