Molecular Size and Structure of Asphaltenes from Various Sources

Groenzin, Henning; Mullins, Oliver C.

doi:10.1021/ef990225z

Cited by 822 publications

(849 citation statements)

References 22 publications

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“…However, quantifying the molecular weight of asphaltenes has been a matter of considerable controversy 16 . One of the major difficulties for interpreting the data comes from the wide range of molecular weights observed experimentally when using different measurement methods.…”

Section: The Study Of Asphaltene Aggregationmentioning

confidence: 99%

Changes in Asphaltene Microenvironments Evidenced by Fluorescence Solvatochromism

Pietraru

Cramb

2003

Langmuir

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This work involved the study of Cold Lake asphaltenes' behavior in toluene and o-dichlorobenzene. The changes in asphaltene microenvironments with the increase in asphaltene concentration were observed using fluorescence solvatochromism. The reporter molecule chosen was the environmentally sensitive fluorophore PRODAN. This procedure represents a novel and sensitive method to study asphaltene solutions, and might bring additional information to the existent database of asphaltene properties.A pre-aggregation model was developed to explain the experimental observations, and a definition for the critical aggregation concentration was proposed. The model is valid for low asphaltene concentrations and is supported by direct measurements of refractive indices for asphaltene solutions. Atomic force microscopy was used to image asphaltene entities. The size distribution indicated that asphaltene particles do not change significantly with the increase in concentration. The appearance of larger aggregates in solutions with concentrations above CAC might support the validity of the model.

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Section: The Study Of Asphaltene Aggregationmentioning

confidence: 99%

Changes in Asphaltene Microenvironments Evidenced by Fluorescence Solvatochromism

Pietraru

Cramb

2003

Langmuir

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“…Asphaltenes are defined according to their solubility, i.e., as the fraction of the crude oil which is soluble in toluene and precipitates in low boiling point alkanes (n-pentane, n-heptane). Two of the representative structures for the asphaltene molecules belong to the ''island'' and ''archipelago'' structures (Groenzin and Mullins 2000;Acevedo et al 2007). According to ''island'' structure, the most dominant part of the molecule is a planar polycyclic aromatic system containing on average 7 aromatic rings, and this aromatic system has poor alkyl substitution.…”

Section: Introductionmentioning

confidence: 99%

Waxes in asphaltenes of crude oils and wax deposits

2016

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Composition and molecular mass distribution of n-alkanes in asphaltenes of crude oils of different ages and in wax deposits formed in the borehole equipment were studied. In asphaltenes, n-alkanes from C 12 to C 60 were detected. The high molecular weight paraffins in asphaltenes would form a crystalline phase with a melting point of 80-90°C. The peculiarities of the redistribution of high molecular paraffin hydrocarbons between oil and the corresponding wax deposit were detected. In the oils, the high molecular weight paraffinic hydrocarbons C 50 -C 60 were found, which were not practically detected in the corresponding wax deposits.

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“…Thus, for the much larger T 0 in combustors, it is expected that the mean molar mass of the liquid will increase from the present values, leading to coke or cenosphere formation when species as heavy as ϳ500 kg/ kmol have a non-negligible presence in the drop. [38][39][40] Complementary to P͑ l ͒, P͑ l ͒ shows that the preferred value is similar for both lower-stream and mixinglayer regions, and that the location of the peak slightly increases with larger T 0 . Independent of T 0 , the P͑ l ͒ width is larger in the mixing layer, consistent with the information in Fig.…”

Section: -24mentioning

confidence: 82%

Characteristics of transitional multicomponent gaseous and drop-laden mixing layers from direct numerical simulation: Composition effects

Selle

Bellan

2007

Physics of Fluids

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Transitional states are obtained by exercising a model of multicomponent-liquid ͑MC-liquid͒ drop evaporation in a three-dimensional mixing layer at larger Reynolds numbers, Re, than in a previous study. The gas phase is followed in an Eulerian frame and the multitude of drops is described in a Lagrangian frame. Complete dynamic and thermodynamic coupling between phases is included. The liquid composition, initially specified as a single-Gamma ͑SG͒ probability distribution function ͑PDF͒ depending on the molar mass, is allowed to evolve into a linear combination of two SGPDFs, called the double-Gamma PDF ͑DGPDF͒. The compositions of liquid and vapor emanating from the drops are calculated through four moments of their PDFs, which are drop-specific and location-specific, respectively. The mixing layer is initially excited to promote the double pairing of its four initial spanwise vortices, resulting into an ultimate vortex in which small scales proliferate. Simulations are performed for four liquids of different compositions, and the effects of the initial mass loading and initial free-stream gas temperature are explored. For reference, simulations are also performed for gaseous multicomponent mixing layers for which the effect of Re is investigated in the direct-numerical-simulation-accessible regime. The results encompass examination of the global layer characteristics, flow visualizations, and homogeneous-plane statistics at transition. Comparisons are performed with previous pretransitional MC-liquid simulations and with transitional single-component ͑SC͒ liquid-drop-laden mixing layer studies. Contrasting to pretransitional MC flows, the vorticity and drop organization depend on the initial gas temperature, this being due to drop/turbulence coupling. The vapor-composition mean molar mass and standard deviation distributions strongly correlate with the initial liquid-composition PDF. Unlike in pretransitional situations, regions of large composition standard deviation no longer necessarily coincide with those of large mean molar mass. The rotational and composition characteristics are all liquid-specific and the variation among liquids is amplified with increasing free-stream gas temperature. The classical energy cascade is found to be of similar strength, but the smallest scales contain orders of magnitude less energy than SC flows, which is confirmed by the larger viscous dissipation for MC flows. The kinetic energy and dissipation are liquid-specific and the variation among liquids is amplified with increasing free-stream gas temperature. The gas composition, of which the first four moments are calculated, is shown to be close to, but distinct from, a SGPDF. Eulerian and Lagrangian statistics of gas-phase quantities show that the different observation framework may affect the perception of the flow.

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Molecular Size and Structure of Asphaltenes from Various Sources

Cited by 822 publications

References 22 publications

Changes in Asphaltene Microenvironments Evidenced by Fluorescence Solvatochromism

Changes in Asphaltene Microenvironments Evidenced by Fluorescence Solvatochromism

Waxes in asphaltenes of crude oils and wax deposits

Characteristics of transitional multicomponent gaseous and drop-laden mixing layers from direct numerical simulation: Composition effects

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