Study of Brazilian asphaltene aggregation by Nuclear Magnetic Resonance spectroscopy

Oliveira, Emanuele Catarina da Silva; Neto, Álvaro Cunha; Júnior, Valdemar Lacerda; Castro, Eustáquio Vinícius Ribeiro de; Menezes, Sônia Maria Cabral de

doi:10.1016/j.fuel.2013.09.022

Cited by 69 publications

(72 citation statements)

References 21 publications

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“…S4 online) illustrate left-skewed distributions with a mild even-odd predominance of medium molecular weight compounds. We calculated the ratio of even-odd medium molecular-weight n-alkanoic acids (C 12-18 to C [11][12][13][14][15][16][17] ) as an indicator of biological activity 66 (Table 2), which was 1.711 and 1.33 for E1 and E2 respectively. Note that the high C 16 and C 18 peaks also drive the even-odd predominance of E1 which is highest out of the four samples.…”

Section: Rico Of Asphaltenesmentioning

confidence: 99%

“…Their solubilisation may change depending on solvent 9 and the number of aromatic rings 10 . The asphaltene molecules have a wide distribution of architectures with two broad types, island and archipelago 11 , recently thought of as two extremes of a structural continuum [12][13][14] . The island architecture is most common 11,15,16 and comprises a single polycyclic aromatic hydrocarbon (PAH) centre and aliphatic appendages 11,15 .…”

Section: Introductionmentioning

confidence: 99%

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Determination of Asphaltene Critical Nanoaggregate Concentration Region Using Ultrasound Velocity Measurements

Svalova

Parker

Povey

et al. 2017

Sci Rep

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Asphaltenes constitute the heaviest, most polar and aromatic fraction of petroleum crucial to the formation of highly-stable water-in-crude oil emulsions. The latter occur during crude oil production as well as spills and cause difficulties to efficient remediation practice. It is thought that in nanoaggregate form, asphaltenes create elastic layers around water droplets enhancing stability of the emulsion matrix. Ultrasonic characterisation is a high-resolution non-invasive tool in colloidal analysis shown to successfully identify asphaltene nanoaggregation in toluene. The high sensitivity of acoustic velocity to molecular rearrangements and ease in implementation renders it an attractive method to study asphaltene phase properties. Currently, aggregation is thought to correspond to an intersection of two concentration-ultrasonic velocity regressions. Our measurements indicate a variation in the proximity of nanoaggregation which is not accounted for by present models. We attribute this uncertainty to physico-chemical heterogeneity of the asphaltene fraction driven by variation in molecular size and propose a critical nanoaggregation region. We treated asphaltenes from North and South American crude oils with ruthenium ion catalysed oxidation to characterize their n-alkyl appendages attached to aromatic cores. Principal component analysis was performed to investigate the coupling between asphaltene structures and velocity measurements and their impact on aggregation.

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Section: Rico Of Asphaltenesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Determination of Asphaltene Critical Nanoaggregate Concentration Region Using Ultrasound Velocity Measurements

Svalova

Parker

Povey

et al. 2017

Sci Rep

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show abstract

“…Different authors have suggested models with one or the other being predominant for different asphaltene samples (e.g., refs. [19][20][21][22][23][24][25] favour the archipelago architecture and [26][27][28][29][30][31] favour the continental) or asphaltene fractions [32], notwithstanding that the reliability of some common experimental methods may be a matter of concern [33][34][35]. A predominant molecular structure for asphaltenes supporting the continental archetype has been identified in the Yen-Mullins model [36][37][38] (cf.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic modelling of asphaltene precipitation and related phenomena

Forte

Taylor

2015

Advances in Colloid and Interface Science

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“…Due to a decrease in light oil reserves, the main goal today is to refine large quantities of heavy crude oils, to transform them into good quality commercial products with low operational costs and to obey the environmental specification. 1,2 The composition of crude oil is generally assessed by the standard methods such as ASTM methods (American Society for Testing and Materials) which are time consuming, elaborate and expensive, requiring substantial amounts of the samples and appropriate solvents. Hence, faster, cheaper and simpler methods are highly needed.…”

Section: Introductionmentioning

confidence: 99%

“…15,16 Despite many efforts and variety of analytical methods used, accurate data on molecular weight, size, shape and structure of asphaltenes are still scarce in the literature and their properties not completely elucidated. 1,2,14 We applied here a pseudo two dimensional DOSY NMR technique to preliminary characterize composition and structure of these complex molecular systems.…”

Section: Introductionmentioning

confidence: 99%

NMR and Chemometric Characterization of Vacuum Residues and Vacuum Gas Oils from Crude Oils of Different Origin

Vuković¹,

Novak²,

Plavec³

et al. 2015

Croat. Chem. Acta

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Abstract. NMR spectroscopy in combination with statistical methods was used to study vacuum residues and vacuum gas oils from 32 crude oils of different origin. Two chemometric metodes were applied. Firstly, principal component analysis on complete spectra was used to perform classification of samples and clear distinction between vacuum residues and vacuum light and heavy gas oils were obtained. To quantitatively predict the composition of asphaltenes, principal component regression models using areas of resonance signals spaned by 11 frequency bins of the 1 H NMR spectra were build. The first 5 principal components accounted for more than 94 % of variations in the input data set and coefficient of determination for correlation between measured and predicted values was R 2 = 0.7421. Although this value is not significant, it shows the underlying linear dependence in the data. Pseudo two-dimensional DOSY NMR experiments were used to assess the composition and structural properties of asphaltenes in a selected crude oil and its vacuum residue on the basis of their different hydrodynamic behavior and translational diffusion coefficients. DOSY spectra showed the presence of several asphaltene aggregates differing in size and interactions they formed. The obtained results have shown that NMR techniques in combination with chemometrics are very useful to analyze vacuum residues and vacuum gas oils. Furthermore, we expect that our ongoing investigation of asphaltenes from crude oils of different origin will elucidate in more details composition, structure and properties of these complex molecular systems.

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Study of Brazilian asphaltene aggregation by Nuclear Magnetic Resonance spectroscopy

Cited by 69 publications

References 21 publications

Determination of Asphaltene Critical Nanoaggregate Concentration Region Using Ultrasound Velocity Measurements

Determination of Asphaltene Critical Nanoaggregate Concentration Region Using Ultrasound Velocity Measurements

Thermodynamic modelling of asphaltene precipitation and related phenomena

NMR and Chemometric Characterization of Vacuum Residues and Vacuum Gas Oils from Crude Oils of Different Origin

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