Molecular Representations of Ratawi and Alaska North Slope Asphaltenes Based on Liquid- and Solid-State NMR

Storm, D. A.; Edwards, John C.; DeCanio, Stephen J.; Sheu, Eric Y.

doi:10.1021/ef00045a007

Cited by 83 publications

(76 citation statements)

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“…A summary of the compositional data for the Ratawi asphaltenes from Storm et al (1990Storm et al ( ,1991 is given in Table 1. Other characterization details for these samples, including rheological and colloidal properties, are given in Storm et al (1990Storm et al ( ,1991Storm et al ( ,1992Storm et al ( ,1993 and Sheu et al (1991Sheu et al ( ,1992. Two different solutions were prepared by dissolving the asphaltene sample in pyridine at concentrations above (5.1 X 10-2 wt %) and below (1.0 X 10-2 wt %) the critical micelle concentration (cmc).…”

Section: Methodsmentioning

confidence: 99%

“…In general, asphaltenes are believed to be polynuclear aromatic ring systems bearing alkyl side chains. The condensed ring systems vary in size from 6 to 20 rings and the alkyl chain lengths between 4 and 20 carbon atoms (Hasan et al, 1989;Mojelsky et al, 1992;Payzant et al, 1991;Storm et al, 1993). The apparent high molecular weight of asphaltenes (2000-10 000) is attributed to the linking together of the aromatic sheets with alkyl chains (Speight, 1991).…”

Section: Introductionmentioning

confidence: 99%

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Imaging of Petroleum Asphaltenes Using Scanning Tunneling Microscopy

Watson¹,

Barteau²

1994

Ind. Eng. Chem. Res.

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Scanning tunneling microscopy (STM) was used to image Ratawi (neutral zone) asphaltenes deposited on highly oriented pyrolytic graphite (HOPG). STM images revealed the formation of ordered arrays covering hundreds of angstroms of the surface. Samples deposited from pyridine solutions above and below the critical micelle concentration were quite similar. The individual features imaged in these arrays were attributed to the termini of the pendant aliphatic chains known to be a part of the asphaltene molecular structure. The ordered arrays imaged were extremely flat and uniform, in contrast to the assumed molecular complexity and the absence of unique structure of asphaltenes. The formation of these ordered surface arrays is further evidence of the tendency of asphaltenes to self-associate.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Imaging of Petroleum Asphaltenes Using Scanning Tunneling Microscopy

Watson¹,

Barteau²

1994

Ind. Eng. Chem. Res.

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“…Overall composition was chosen to resemble the total C/H ratio reported for a real asphalt. 34,35 In the asphaltene1-based system, we used 5 of a model asphaltene molecule suggested by Artok et al, 31 27 1,7-dimethylnaphthalene, and 41 n-C 22 molecules; in the asphaltene2-based system, we used 5 of a model asphaltene molecule suggested by Groenzin and Mullins, 32 35 1,7-dimethylnaphthalene, and 45 n-C 22 molecules.…”

Section: A Ternary Asphalt Systemsmentioning

confidence: 99%

Relaxation time, diffusion, and viscosity analysis of model asphalt systems using molecular simulation

Zhang

Greenfield

2007

The Journal of Chemical Physics

181

131

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Molecular dynamics simulation was used to calculate rotational relaxation time, diffusion coefficient, and zero-shear viscosity for a pure aromatic compound ͑naphthalene͒ and for aromatic and aliphatic components in model asphalt systems over a temperature range of 298-443 K. The model asphalt systems were chosen previously to represent real asphalt. Green-Kubo and Einstein methods were used to estimate viscosity at high temperature ͑443.15 K͒. Rotational relaxation times were calculated by nonlinear regression of orientation correlation functions to a modified Kohlrausch-Williams-Watts function. The Vogel-Fulcher-Tammann equation was used to analyze the temperature dependences of relaxation time, viscosity, and diffusion coefficient. The temperature dependences of viscosity and relaxation time were related using the Debye-Stokes-Einstein equation, enabling viscosity at low temperatures of two model asphalt systems to be estimated from high temperature ͑443.15 K͒ viscosity and temperature-dependent relaxation time results. Semiquantitative accuracy of such an equivalent temperature dependence was found for naphthalene. Diffusion coefficient showed a much smaller temperature dependence for all components in the model asphalt systems. Dimethylnaphthalene diffused the fastest while asphaltene molecules diffused the slowest. Neat naphthalene diffused faster than any component in model asphalts.

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“…In liquid and solid-state NMR, for example, different types of structural entities can be identified and quantified [20]. Therefore, the liquid extracts (HS, HIS-TS and TIS-THFS) were further characterized by 1 H and 13 C NMR to examine the distribution of carbon and hydrogen according to various structural groups found in aliphatic and aromatic moieties [21][22][23][24]. As for the pilot plant-produced sediment sample and its THFIS residue solid-state 13 C NMR was applied.…”

Section: Nmrmentioning

confidence: 99%