Characterization of asphaltenes and co-precipitated material from a Californian crude oil

Myhr, May Britt; Schou, L.; Skjetne, Tore; Krane, Jostein

doi:10.1016/0146-6380(90)90129-n

Cited by 14 publications

(15 citation statements)

References 5 publications

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“…Gas chromatographic data confirmed that F1-1 contained alkanes only, with characteristic patterns of linear and branched molecules from C 10 to C 30 . Note that all abovelisted IR bands (r CH 2 excepted) were observed in other fractions as well, evidencing the ubiquous importance of aliphatic groups in asphaltene structures.…”

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confidence: 76%

“…UV-fluorescence spectra before or after light exposure were not significantly different; similarly, 1 H NMR and 13 C NMR spectra were unchanged. With reference to current knowledge [17,[22][23][24][25][26][27][28][29][30], these negative data suggested that hydrocarbon skeletons underwent little alteration if any during light exposure. Table III presents the relative changes in gravimetric distribution of asphaltenes among the different eluted fractions.…”

Section: Spectral Analysismentioning

confidence: 95%

“…Samples were irradiated at room temperature for 30 [14,17]: dispersion, dipole-dipole, proton donor, proton acceptor).…”

Section: Photo-oxidationmentioning

confidence: 99%

“…After 80 and 140 days, "new" alkanes and long-chained alkyl benzenes were produced. They might either originate from radical reactions, or represent compounds originally trapped in the asphaltene matrix [30] and released by its photo-oxidation [10].…”

Section: Fraction Analyses After Light Exposure Fractions 1 Andmentioning

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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mentioning

confidence: 76%

Section: Spectral Analysismentioning

confidence: 95%

“…Samples were irradiated at room temperature for 30 [14,17]: dispersion, dipole-dipole, proton donor, proton acceptor).…”

Section: Photo-oxidationmentioning

confidence: 99%

Section: Fraction Analyses After Light Exposure Fractions 1 Andmentioning

confidence: 99%

See 2 more Smart Citations

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

et al. 1998

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“…On the basis of recent detailed NMR, IR, MS along with other complementary analytical techniques (Ali et al, 1990;Artok et al, 1999;Bekerar et al, 1999;Bouhadda et al, 2000;Calemma et al, 1995;Dickinson 1980;Hasan et al, 1988;Ignasik et al, 1977;Li et al, 1997;Myhr et al, 1990;Storm et al, 1994) in addition to some studies dealing oxidative degradation (Strausz et al, 1999a(Strausz et al, , 1999b it has been concluded that asphaltenes are mixtures of polyaromatic units, with heteroatom contents, with some alicyclic rings and substituted and connected with each other via chains. Moreover, in petroleum industry, further utilization of distillation residue is of high interest and thus petroleum industry will have to deal with much heavier crudes in the future.…”

Section: Introductionmentioning

confidence: 99%

Structural Characterization of Different Asphaltenes of Kuwaiti Origin

Ibrahim

Abdelhameed

Al-Sahhaf

et al. 2003

Petroleum Science and Technology

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Asphaltenes obtained by precipitation from crude Kuwaiti oils have been analyzed by proton magnetic resonance ( 1 H-NMR), carbon-13 nuclear magnetic resonance ( 13 C-NMR) and Infrared (IR) spectral techniques. The molecular weight and elemental analysis were also determined. These combined analytical data were used for the characterization of these Kuwaiti oils. The asphaltenes molecular weights range from approximately 4200-6500 with an H/C ratio of 0.91-1.1 with an average 45-71% aromatic carbons. The average side chain length was of 4-6 carbons. It can also be concluded that the asphaltenes under investigation contain 5-9 sets of condensed

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