Structural Characterization of Asphaltenes Obtained from Hydroprocessed Crude Oils by SEM and TEM

Trejo, Fernando; Ancheyta, Jorge; Rana, Mohan S.

doi:10.1021/ef8005405

Cited by 105 publications

(93 citation statements)

References 16 publications

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“…3a focus was made on checking the amorphous white particles of different sizes. As seen in Table III, carbon element is most abundant, in accordance with Trejo [11] studies. Carbon is followed by phosphorus and sulfur.…”

Section: Dnp Parameterssupporting

confidence: 85%

Intermolecular Effects of Fluorocarbons on MC800 Asphaltene and their Characterization

2017

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TurkeyNuclear magnetic resonance and dynamic nuclear polarization experiments were performed to study suspensions of asphaltene in the fluorocarbons at a low magnetic field of 1.53 mT, at room temperature. The asphaltene was extracted from MC800 liquid asphalt, which was of Heavy Iran origin. The elemental composition and the surface morphology of the asphaltene were determined by scanning electron microscopy and energy dispersive X-ray analysis. Intermolecular spin-spin interactions occur between nuclear spins of hydrogen in the solvent medium and the free electron spins in the asphaltene micelles. The electron paramagnetic resonance spectrum of the asphaltene was obtained and the saturation experiments were applied to the samples prepared in vacuum. The main 1 H DNP parameters were listed. Chemical composition and molecular structure of the asphaltene were analyzed. Scanning electron microscope images have shown that asphaltenes are constituted of agglomerated particles and smooth surfaces. Energy dispersive X-ray analysis has shown that the most abundant element is carbon. IntroductionAsphaltenes, which are a part of petroleum, are regarded to be polar species, have larger aromatic structures and are containing alkyl chains, heteroatoms (such as O, S and N) and some metals [1]. Asphaltenes have unpaired electrons, which are observed using the electron spin resonance (ESR) experiments in crude petroleum [2].Dynamic nuclear polarization (DNP) utilizes the liquid state interaction between nuclei and unpaired electron spins to generate an increased nuclear polarization upon the saturation of ESR transitions of the radicals. The maximum DNP enhancement of the NMR signal is given by the electron-to-nuclear gyromagnetic ratios γ e /γ n . This ratio for proton spin is 660. In this study, the nuclear spins are the proton spins, which are the 1 H nuclei of the solvent medium and the electron spins belong to the free electrons on the asphaltene micelles. The unpaired electrons were delocalized on the incomplete carbon bonds of the condensed aromatic structure of the asphaltene particles [3]. By DNP method we have revealed dipolar interaction between hydrogen atoms of the solvent and unpaired electrons of colloidal asphaltene. Electron spin saturation and DNP enhancements have been obtained and DNP parameters determined in low magnetic field. Chemical composition and morphology of MC800 asphaltene were investigated using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis.

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Section: Dnp Parameterssupporting

confidence: 85%

Intermolecular Effects of Fluorocarbons on MC800 Asphaltene and their Characterization

2017

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“…The capability for self-assembly of polyaromatic structures is an often observed phenomenon. Several studies found self-ordering behavior for such molecules and it has been proven that this effect, which is caused by p-p interactions, can also be found in asphaltenes [2,12,13,19,20,55,59,62]. For most bitumina studied in literature, the natural wax fraction is below 2 wt% as measured by standard distillation methods [32], while the typical asphaltene content is around 10 wt%.…”

Section: Discussionmentioning

confidence: 99%

The bitumen microstructure: a fluorescent approach

et al. 2014

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Five bituminous samples were carefully studied by confocal laser scanning microscopy using 488 nm excitation radiation and observing 500-530 nm of emission. The images revealed the microstructure of bitumen. The influence of the admixture of mineral aggregates concerning the microstructure was tested. For the minerals, no significant influence was found. For understanding the origin of fluorescent signals, the samples were separated into asphaltenes and maltenes and analyzed with fluorescence spectroscopy. Although former works have assumed the origin of fluorescent emissions in bitumen to be found in the asphaltene fraction, the asphaltenes produce little to no emissions, but the maltenes exhibit strong fluorescence in the observed spectral region. For deeper insight, fractionation of the bitumina into the SARA fractions by chromatographic column separation was necessary. The fluorescence spectra of these fractions were analyzed and revealed the aromatics and resin phases to be the only components capable of sufficiently intense fluorescent emission. This is a strong argument for a complex internal microstructure consisting of a mantle of aromatics surrounding an inner core.

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“…Figure 10 shows a smooth surface that possesses small pores distributed irregularly over this continuous phase. The formation of these pores or cavities may be due to the previous presence of resinous materials that supported the dispersion of asphaltenes in crude oil, and the cavities are a result of their removal [4,24,39]. In this figure, agglomerated asphaltenes are also seen.…”

Section: Sem Micrographs Taken With a Philips Xl-30 Scanningmentioning

confidence: 95%

“…A major problem in this matter, however, is the high viscosity of the heavy crude oils, and asphaltenes play a central role in this issue (increased viscosity of the heavy oils is associated with an increased asphaltene content) [1,2]. Asphaltenes as the multi-component petroleum fraction are soluble in aromatic solvents and insoluble in low-boilingpoint n-alkane solvents, such as n-pentane and n-heptane [3,4]. According to the solubility results obtained through asphaltene precipitation with the use of mixtures of heptane and toluene solvents (heptol), a lower toluene volume fraction was needed for precipitation of asphaltenes in the presence of resins (1:1 asphaltenes to resins mass ratio) than in the absence of resins.…”

Section: Introductionmentioning

confidence: 99%

Structural Study of Asphaltenes from Iranian Heavy Crude Oil

Davarpanah

Vahabzadeh

Dermanaki

2013

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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and available online here Cet article fait partie du dossier thématique ci-dessous publié dans la revue OGST, Vol. 70, n°6, pp. 909-1132 et téléchargeable ici D o s s i e rOil & Gas Science and Technology -Rev. IFP Energies nouvelles, Vol. 70 (2015), No. 6, pp. 909-1132 Copyright © 2015, IFP Energies nouvelles > Editorial -Enhanced Oil Recovery (EOR), Asphaltenes and HydratesÉditorial -EOR «récupération assistée du pétrole», Asphaltènes et Hydrates D. Langevin and F. Baudin ENHANCED OIL RECOVERY (EOR) > HP-HT Drilling Mud Based on Environmently-Friendly Fluorinated ChemicalsBoues de forage HP/HT à base de composés fluorés respectueux de l'environnement Résumé -Étude structurale d'asphaltènes de pétrole brut lourd iranien -Dans la présente étude, la précipitation d'asphaltènes du pétrole brut lourd iranien (au large du golfe Persique) a été effectuée au moyen de n-pentane (n-C 5 ) et de n-heptane (n-C 7 ) comme alcanes légers précipitants. Plusieurs techniques analytiques, chacune utilisant différents principes, ont ensuite été utilisées pour caractériser la structure des asphaltènes précipités. Le rendement en asphaltènes obtenu par l'utilisation du précipitant n-pentane était plus élevé que pour les asphaltènes précipités à l'aide du n-heptane. L'extraction des asphaltènes a affecté les fractions de maltènes n-C 5 et n-C 7 à des températures inférieures à 204 °C, comme l'indiquent les données obtenues par la technique de distillation simulée. La viscosité du pétrole lourd est influencée par la teneur et le comportement des asphaltènes. La dépendance de la viscosité du pétrole lourd testé avec le taux de cisaillement appliqué a été déterminée et l'écoulement était faible à γ. supérieur à 25 s -1 . Les échantillons de pétrole lourd reconstitués ont été préparés en ajoutant différentes quantités d'asphaltènes aux maltènes (pétrole lourd désasphalté) et les effets des asphaltènes ont été plus prononcés à la basse température de 25 °C, comparés à ceux obtenus à des températures plus élevées. Selon le modèle de loi de puissance utilisé dans cette étude, la fluidité du pétrole lourd testé a révélé un caractère pseudoplastique. Les résultats structuraux obtenus à partir de la spectroscopie InfraRouge à Transformée de Fourier (IRTF) ont montré la présence de différents groupes fonctionnels dans les asphaltènes précipités. Par exemple, la présence de différents hydrocarbures (aliphatique, aromatique et alicyclique), basée sur leurs caractéristiques dans le spectre IRTF, a été confirmée. Les résines sont des dispersants efficaces et le retrait de cette fraction du pétrole brut perturbe la nature colloïdale du pétrole lourd, la floculation et la précipitation des asphaltènes finissant par se produire. L'apparition de pores sur les images SEM (Scanning Electron Microscopy) a été utilisée comme indicateur du détachement de la résine. A l'aide de la spectroscopie de Résonance Magnétique Nucléaire (RMN) 1 H et 13 C, deux paramètres structuraux importants des asphaltènes ont été déterminés. A savoir, l'aromaticité (f a ) et...

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Structural Characterization of Asphaltenes Obtained from Hydroprocessed Crude Oils by SEM and TEM

Cited by 105 publications

References 16 publications

Intermolecular Effects of Fluorocarbons on MC800 Asphaltene and their Characterization

Intermolecular Effects of Fluorocarbons on MC800 Asphaltene and their Characterization

The bitumen microstructure: a fluorescent approach

Structural Study of Asphaltenes from Iranian Heavy Crude Oil

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