Assembly of asphaltene molecular aggregates as studied by near-UV/visible spectroscopy

Evdokimov, Igor N.; Eliseev, N. Yu.; Akhmetov, B.R.

doi:10.1016/s0920-4105(02)00350-9

Cited by 93 publications

(93 citation statements)

References 28 publications

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“…This illustrates that aromaticity of fractions increases in the same order. Note that all the fractions show a peak at 410 nm, which is attributable to the presence of VO 2+ complex [24]. The higher intensity of this peak in asphaltene demonstrates the asphaltene contain higher amount of vanadium impurity.…”

Section: Uv-visible Spectramentioning

confidence: 88%

Separation and characterization of bitumen from Athabasca oil sand

Yoon

Bhatt

Lee³

et al. 2009

Korean J. Chem. Eng.

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Separation and chemical analysis was investigated using bitumen samples from Athabasca oil sand in Alberta. Fractionation according to solubility and polarity has been used to separate bitumen into its fractions. The solvent de-asphaltening was performed by n-pentane solvent (solubility fractionation), and the polarity fractionation using Fuller's earth allows maltene to separate into SARA components (saturates, aromatics, resins and asphaltenes). The SARA components are analyzed comprehensively using elemental analysis (EA), Fourier-transformed infrared (FT-IR), ultraviolet-visible spectroscopy (UV-vis), high performance chromatography (HPLC) and thermogravimetric analysis (TGA). EA (C, H, N, S), heavy metals (Ni, V) concentrations, FT-IR and UV-vis tests provided the explanation of chemical composition. From IR spectra, maltene and saturates/aromatics (sat/aro) contained more aliphatic compounds than resin or asphaltene. Also, IR spectrum of sat/aro was similar to crude oil and VGO (vacuum gas oil). Different UV signal data clearly indicates the contribution of aromatic constituents in the fractions. Using optimized analysis conditions of HPLC, we successfully separated the peaks for bitumen and its fractions. The characteristic peak pattern of SARA (saturates, aromatics, resins, asphaltenes) fractions was observed, and also the peak pattern of sat/ aro was similar to that of crude oil and VGO. However, TGA results revealed that thermal behavior for sat/aro was similar to that of crude oil but different from that of VGO. Also, from the comparison between decomposition temperature of TGA and boiling point, their correspondence was found.

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Section: Uv-visible Spectramentioning

confidence: 88%

Separation and characterization of bitumen from Athabasca oil sand

Yoon

Bhatt

Lee³

et al. 2009

Korean J. Chem. Eng.

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“…It is worth noting that the LDI experiments with the 266-nm laser radiation yield a higher sensitivity owing to the greater absorptivity of the asphaltenes at this shorter wavelength. 9,10 The asphaltene samples for the LDI experiments were prepared with the dried-droplet method from toluene solutions with concentrations in the range 0.5-400 mg l 1 , and 20 µl volumes were spotted onto a flat stainless steel sample plate and dried in air. This resulted in average asphaltene sample densities in the range 0.03-24 µg cm 2 .…”

Section: Laser Desorption/ionization Time-of-flight Mass Spectrometrymentioning

confidence: 99%

“…Interestingly, double-maximum asphaltene mass distributions with a surprisingly close qualitative resemblance to the ones measured in our experiments have been obtained in GPC experiments, 27 and have been later supported by ultraviolet absorption measurements. 9 In addition, earlier studies employing a variety of experimental and theoretical techniques have provided evidence for enhanced stability of specific aggregation numbers, with especially stable compounds incorporating a number of asphaltene units ranging from 2 to 8 depending on the crude oil source. 4 -6,28,31 From our results, it becomes apparent that the band B in the LDI spectra peaking at ¾1800 amu, with an associated number-averaged MW of ¾3100 amu observed in the experiments with 100 µJ/pulse laser energy on the samples with moderate and high asphaltene density, must be associated with a stable aggregate configuration.…”

Section: Dense Asphaltene Samplesmentioning

confidence: 99%

On the determination of molecular weight distributions of asphaltenes and their aggregates in laser desorption ionization experiments

et al. 2006

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Molecular weight distributions (MWD) of asphaltenes and their aggregates have been investigated in laser desorption ionization (LDI) mass spectrometric experiments. A systematic investigation of the dependence of the measured MWD on the asphaltene sample density and on the laser pulse energy allows the assignment of most probable molecular weights within 300-500 amu and average molecular weights of 800-1000 amu for the monomeric asphaltenes, as well as for the estimation of the contribution from asphaltene clusters in typical LDI measurements. The results serve to reconcile the existing controversy between earlier mass spectrometric characterizations of asphaltenes based on laser desorption techniques by different groups. Furthermore, the MWD measurements performed on particularly dense samples yield an additional differentiated broad band peaking around 9000-10,000 amu and extending over 20,000 amu, not observed previously in LDI experiments, thereby revealing a strong propensity of the asphaltenes to form clusters with specific aggregation numbers, which is in qualitative agreement with previous theoretical predictions and with the interpretation of measurements performed with other techniques.

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“…Association of asphaltenes in solutions has been the subject of a number of studies, Evdokimov et al [14][15][16], Sheu [17] in which The reported concentrations of aggregation were typically in the range 2-18 g/L, depending on a solvent. Asphaltenes precipitation is one of the problems affecting crude oil production and refining processes.…”

Section: Introductionmentioning

confidence: 99%

Dispersing of Petroleum Asphaltenes by Acidic Ionic Liquid and Determination by UV-Visible Spectroscopy

Nezhad

Heidarizadeh

Sajjadifar

et al. 2013

Journal of Petroleum Engineering

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Nowadays, constructing a mechanism to prevent the aggregation petroleum asphaltenes by the use of new acidic ionic liquids has become of fundamental importance. In this research, 3-(2-carboxybenzoyl) were tested. It should be noted that during the experiment the presence of the acidic ionic liquid moiety enhanced interactions between asphaltenes and acidic ionic liquids and it greatly limited asphaltene aggregation. We considered parameters such as temperature, amount of dispersant, effect of water: toluene ratio, the stirring time and effects of other ionic liquids, and determination of concentration of petroleum asphaltenes after dispersing by acidic ionic liquid under various parameters using UV-Visible spectroscopy.

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Assembly of asphaltene molecular aggregates as studied by near-UV/visible spectroscopy

Cited by 93 publications

References 28 publications

Separation and characterization of bitumen from Athabasca oil sand

Separation and characterization of bitumen from Athabasca oil sand

On the determination of molecular weight distributions of asphaltenes and their aggregates in laser desorption ionization experiments

Dispersing of Petroleum Asphaltenes by Acidic Ionic Liquid and Determination by UV-Visible Spectroscopy

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