Étude des spectres IRTF de charbons français déminéralisés et de leurs macéraux

Guliano, M.; Mille, G.; Kister, Jacky; Muller, J. F.

doi:10.1051/jcp/1988850963

Cited by 21 publications

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“…Main bands detected in FTIR spectra are listed in table II and assigned to respective functions according to current knowledge [11,19,20]. As preliminary reported in a previous note [21], this global approach failed to evidence significant changes even after maximal light exposure (140 days).…”

Section: Spectral Analysismentioning

confidence: 77%

“…In phenols, the O−H bending and C−O stretching vibrations are strongly coupled and give rise to a marked band between 1260 and 1180 cm -1 [15]. On the other hand, the 1600 cm −1 band has now been assigned to aromatic C = C bond stretching vibrations, while its intensity depends on the nature of the ring substituents [19]. With OH groups (mainly in ortho and para positions) absorption can be especially intense.…”

Section: Fractionmentioning

confidence: 99%

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A fraction to fraction study of photo-oxidation of BAL 150 crude oil asphaltenes

et al. 1998

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IntroductionAmong several intricate physical, physico-chemical, and biological factors, natural light plays an important role [1][2][3][4][5][6] in the mitigation of oil spills at sea or ground surface. Nevertheless, little is known about the contribution of photooxidation to the lengthy degradation of asphaltenes [7][8][9][10][11], the most recalcitrant fraction to weathering processes. Their extremely complex composition probably accounts for this lack of data, by making gradual changes outstandingly difficult to investigate.The chemical nature of asphaltenes is poorly defined. In fact, they correspond to a solubility class of constituents: these precipitated from crude oils by adding at least 40 volumes of normal alkanes (nC 5 to nC 7 ). Asphaltenes contain lamellar macromolecules resulting from the condensation of polyaromatic, naphthenic and heterocyclic nuclei, bearing alkyl side chains and sometimes functionalized. Their molecular weight varies from several hundreds to several thousands [12,13]. Cross linked by alkyl, sulphur and oxygen bridges, the polycyclic sheets constitute a matrix that traps various aliphatic hydrocarbons, and form micelles spread among the other petroleum constituents (hydrocarbons and resins).Addressing chemical changes in such structures is a technical challenge, and hence separating samples into different fractions is an unescapable step before analysis. To investigate the effects of light in asphaltenes isolated from Blend Arabian Light crude oil, samples were fractionated by sequential elution solvent chromatography [14]. This technique, suitable for liquid coals [15][16], and adapted to crude oil asphaltenes [17] was selected, for it separates compounds according to functionalities. Subsequent analyses involved gravimetry, elemental analysis, NMR, UV-fluorescence and chiefly FTIR spectroscopy. Materials and methodsThe effects of light exposure were studied in asphaltenes separated from Blend Arabian Light topped at 150°C (BAL 150). In addition, a number of asphaltenes from several other crude oils (Rospo Mare, Ekofisk, Oman, Handil, Irak, Saoudian (PBS), Kuwait, Shengli, Bach Ho, Zarzaïtine, Blend Arabian Medium and Bunker C) were fractionated and investigated to elucidate some FTIR data. Precipitation of asphaltene fractionsAsphaltenes were precipitated in compliance with the NFT 60-115 AFNOR standard [18]. Crude oil (5 g) was mixed to n-heptane (200 mL) in a 250 mL round bottom flask, heated to reflux (90°C) under agitation during 2.5 hr, and then allowed to settle for 12 hr at room temperature. This solution was filtered on a glass microfiber filter (Whatman GF/A, porosity 0.45 µm). Warm heptane was used to drain out the precipitate coating the flask wall, and to thoroughly rinse the solid collected on the filter. The solid was dissolved with dichloromethane; the solution was then concentrated in a rotary evaporator and dried under nitrogen flow up to complete solvent elimination. In the case of BAL 150 crude oil, this technique yielded an asphaltene fraction of about 3%. ...

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Section: Spectral Analysismentioning

confidence: 77%

Section: Fractionmentioning

confidence: 99%

A fraction to fraction study of photo-oxidation of BAL 150 crude oil asphaltenes

et al. 1998

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“…The main IR bands were determined using indices that had been described in earlier studies (Guiliano et al, 1988). These indices were employed to determine and compare the chemical composition of each sample.…”

Section: Spectrum and Indexes Significationmentioning

confidence: 99%

“…This procedure is based on the Fourier Transform Infra Red (FTIR) spectroscopy. The FTIR spectroscopy technique gives reliable information regarding the chemical composition of complex mixtures such as crude oils including details on various aliphatic and aromatic compounds, oxygenation rate, and condensation degree of polyaromatic compounds (Guiliano et al, 1988;Boukir et al, 1998). The main advantage of this technique is to work with raw samples, without modifying the internal equilibrium, and to take into account the global composition (Kister et al, 1993.…”

Section: Introductionmentioning

confidence: 99%

Reservoir compartmentalization assessment by using FTIR spectroscopy

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Rébufa

Kister

2007

Journal of Petroleum Science and Engineering

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“…Changes in this spectral range compared with the spectrum of the original coal are less substantial. In the spectra of all the coals, there are three absorption bands with maxima near 875, 835, and 800 cm -1 , which usually are associated with out-of-plane bending vibrations of isolated (850-890 cm -1 range), two adjacent (815-830 cm -1 ), and three adjacent (775-800 cm -1 ) aromatic CH bonds [29]. The relative intensity of the absorption bands for the out-ofplane vibrations provide information about the degree of condensation of aromatic clusters in coals [28].…”

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Infrared absorption spectra of coals with different degrees of coalification

et al. 2007

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We have used Fourier transform IR spectroscopy to study structural changes in coals of different degrees of coalification when stored for prolonged periods under normal conditions. As a result of reaction of the surface of the coals with atmospheric oxygen and water vapor, the intensities of characteristic absorption bands were enhanced which, when we considered elemental analysis data for the coals, allowed us to obtain additional information about their structure and impurity composition.Introduction. Coals consist of complex, high molecular weight, structurally organized systems [1], and so IR spectroscopy is a convenient and informative method for studying them. Using a Fourier transform IR (FTIR) spectrometer makes it possible to highly accurately determine the position of the absorption bands and to carry out semiquantitative analysis of the hydroxyl (OH) groups, aromatic and aliphatic CH groups, carboxyl COOH groups, mineral components, and other functional groups in coals and coal extracts [2,3].The degree of coalification (the carbon atom content), which varies during the natural process of coal formation, and the reflection coefficient of light, depending on the molecular structure of the coals, are usually used to characterize coals [4]. In an optical study of coals, we need to take into account the nonuniformity of their chemical composition and their porosity. Study of the optical properties of coals with high carbon content (≥70 at.%) is made difficult by the low intensity of spectrally poorly resolved absorption bands in the IR region [5].There have been many attempts to study the structure of coals after vacuum annealing [6], thermal decomposition [7], oxidation [8], treatment in acids and bases [9] in order to modify the intensity of individual IR absorption bands of the coals and to obtain additional information about their composition, structure, and properties. The aim of this work was to use IR spectroscopy to determine the effect of the degree of coalification on the structure of coals during their prolonged oxidation under normal conditions. In addition, we used x-ray spectral microanalysis to characterize the samples.Experimental Section. Samples and study procedure. Samples of natural coals (lumps weighing ≈15 g) from the Donetsk field were stored for 20 years at room temperature in air away from light. X-ray spectral microanalysis of the samples was carried out on a scanning electron microscope (LEO1455VP, Carl Zeiss, Germany) using an energy dispersive SiLi detector (Rontec, Germany). The content of a number of chemical elements in the samples was determined by x-ray microanalysis. We should note that in the x-ray microanalysis, with electron beam energy 20 keV the near-surface region of the oxygen-enriched coal was studied (electron penetration depth down to 10 µm). Hydrogen atoms were not detected by this method. Four samples were numbered by Roman numerals in order of decrease of the atomic carbon concentration in them: from 81 to 65 at.% (see Table 1).For the FTIR measurements, piec...

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Étude des spectres IRTF de charbons français déminéralisés et de leurs macéraux

Cited by 21 publications

References 0 publications

A fraction to fraction study of photo-oxidation of BAL 150 crude oil asphaltenes

A fraction to fraction study of photo-oxidation of BAL 150 crude oil asphaltenes

Reservoir compartmentalization assessment by using FTIR spectroscopy

Infrared absorption spectra of coals with different degrees of coalification

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