Analysis of Asphaltenes and Asphaltene Model Compounds by Laser-Induced Acoustic Desorption/Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Pinkston, David S.; Duan, Penggao; Gallardo, Vanessa A.; Habicht, Steven C.; Tan, Xiaoli; Qian, Kuangnan; Gray, Murray R.; Müllen, Kläus; Kenttämaa, Hilkka I.

doi:10.1021/ef9006005

Cited by 125 publications

(131 citation statements)

References 56 publications

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“…According to Yen-Mullins model, asphaltene molecules are dominated by island architecture with most probable molecular weight of 750 Da, as supported by recent mass spectral analysis. [39][40][41] Approximately six asphaltene molecules form a nanoaggregate via -stacking of their PAH cores. The asphaltene nanoaggregates can further associate to form clusters with aggregation numbers of approximately eight.…”

Section: Asphaltenesmentioning

confidence: 99%

Fractionation of Asphaltenes in Understanding Their Role in Petroleum Emulsion Stability and Fouling

et al. 2017

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SARA fractionation separates the oil into fractions of saturates (S), aromatics (A), resins (R), and asphaltenes (A) based on the differences in their polarizability and polarity.Defined as a solubility class, asphaltenes are normally considered as a menace in the petroleum industry mainly due to their problematic precipitation and adsorption at oil water and oil-solid interfaces. As a broad range of molecules fall within the group of asphaltenes with distinct sizes and structures, considering the asphaltenes as a whole was noted to limit the deep understanding of governing mechanisms in asphaltene-induced problems.Extended-SARA (E-SARA) is being proposed as a concept of asphaltene fractionation according to their interfacial activities and adsorption characteristics, providing critical information to correlate specific functional groups with certain characteristics of asphaltene aggregation, precipitation and adsorption. Such knowledge obtained is essential to addressing asphaltene-related problems by targeting specific subfractions of asphaltenes for selective removal.2

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Section: Asphaltenesmentioning

confidence: 99%

Fractionation of Asphaltenes in Understanding Their Role in Petroleum Emulsion Stability and Fouling

et al. 2017

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“…Asphaltenes have a tendency to degrade and aggregate upon introduction into the gas phase. 28,[37][38][39] Dissolution of asphaltenes for mass spectrometry experiments requires a careful choice of a solvent. 28,40 Ionization bias is another concern because of the highly complex composition of asphaltenes.…”

Section: Introductionmentioning

confidence: 99%

“…37,[42][43]44 A variety of additional desorption/ionization methods have been utilized for asphaltene analysis, such as matrix-assisted laser desorption/ionization, 14 field desorption/field ionization, 45 and laser-induced acoustic desorption/electron ionization. 39 In this work, positive ion mode APCI doped with carbon disulfide (CS 2 ) was used to evaporate and ionize six petroleum asphaltene samples of different geographical origins in a linear quadrupole ion trap (LQIT) mass spectrometer. CS 2 reagent has been demonstrated previously to generate stable molecular ions for asphaltenes.…”

Section: Introductionmentioning

confidence: 99%

Structural Comparison of Asphaltenes of Different Origins Using Multi-stage Tandem Mass Spectrometry

et al. 2015

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In this work, six petroleum asphaltene samples of different geographical origins were studied using atmospheric pressure chemical ionization (APCI) in positive ion mode in a linear quadrupole ion trap mass spectrometer (LQIT). APCI doped with carbon disulfide reagent was selected as the ionization method as it has been previously demonstrated to generate stable molecular ions with no fragmentation for asphaltene molecules. The mass spectra measured using this approach revealed the apparent molecular weights (MWs) of the molecules in the asphaltene samples. The results show that petroleum asphaltenes from the American continent, Europe and China have similar apparent molecular weight distributions, ranging from 200 up to 1450 Da, with slightly different apparent average MWs ranging from 570 to 700 Da. Further, molecular ions with eight randomly selected mass-to-charge ratios (m/z) ranging from m/z 500 up to m/z 808 were isolated for each asphaltene sample and subjected to collisionally activated dissociation (CAD) at the same collision energy to examine their structures. The CAD mass spectra (MS 2 experiment) provided information on the maximum total number of carbons in the alkyl chains and the smallest possible size of the aromatic cores in the ionized molecules. Additionally, MS 3 experiments were performed to investigate the fragmentation patterns of the fragment ions generated in the MS 2 experiments. The results obtained support the island structural model for these asphaltenes. Moreover, molecules of greater MWs are shown to have more carbons in alkyl chains (ranging from 17 to 41) but the minimum core size is fairly constant.

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“…Recently, Pinkston et al 36 reported the results from analysis of asphaltenes and asphaltene model compounds by laserinduced acoustic desorption/Fourier transform ion cyclotron resonance mass spectrometry. The authors measured the asphaltenes isolated from a North American crude oil and obtained a MW distribution in the range of 350-1050 Da.…”

mentioning

confidence: 99%

“…Then, the authors concluded that additional studies of alkylated model compounds with bridges are required to define their behavior during the analysis procedures from their instrumentation. 36 Therefore, their analysis results concerning the fundamental properties of asphaltenes are still doubtful.…”

mentioning

confidence: 99%

Discussion on the Structural Features of Asphaltene Molecules

Liao¹,

Zhao²,

Creux³

et al. 2009

Energy Fuels

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Asphaltenes are a class of complex mixtures in petroleum fluids, which are defined as the fraction in petroleum oils soluble in aromatic solvents, such as toluene, whereas insoluble in saturated hydrocarbons, such as n-heptane, and asphaltenes are prepared from crude oils by this simple principle. From this operational definition, asphaltenes are anticipated as a group of complex compounds, 1,2 which are highly polydispersed and cannot be absolutely prescribed by some simplex physicochemical parameters. 3,4 There are fewer large aggregates and narrower distributions once asphaltenes are in infinite-diluted systems of higher temperatures and better solvents; however, they still exhibit a real polydispersity. [1][2][3][4] The average molecular weight (MW) is not necessarily a good parameter to characterize asphaltenes, simply because asphaltenes are defined through their solubility in aliphatic hydrocarbons. 1 Time-resolved fluorescence depolarization (TRFD) was applied to determine the average MW and structural features of asphaltenes by the research group of Mullins, [5][6][7][8][9][10][11][12] and the authors arrived at three primary conclusions: (1) petroleum asphaltenes have an average molecular mass of ∼750 Da (even smaller as 500 Da for coal-derived asphaltenes), with a full width at half-maximum of 500-1000 Da; (2) asphaltenes are dominated by molecules with one polycyclic aromatic hydrocarbon (PAH) unit per molecule; and (3) the most likely asphaltene PAH has roughly 7 rings. However, this method (TRFD) has been reported as being unsuitable for the study of asphaltenes. 2,13,14 The fundamental properties of asphaltenes,

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Analysis of Asphaltenes and Asphaltene Model Compounds by Laser-Induced Acoustic Desorption/Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Cited by 125 publications

References 56 publications

Fractionation of Asphaltenes in Understanding Their Role in Petroleum Emulsion Stability and Fouling

Fractionation of Asphaltenes in Understanding Their Role in Petroleum Emulsion Stability and Fouling

Structural Comparison of Asphaltenes of Different Origins Using Multi-stage Tandem Mass Spectrometry

Discussion on the Structural Features of Asphaltene Molecules

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