HP‐GPC characterization of asphalts

Leite, Leni Figueiredo Mathias; Camillo, M.C.F; Deane, Geoffrey; Brandão, Lc; Cintra, R. H.; Carvalho, Jéssica Rodrigues

doi:10.1002/jhrc.1240120723

Cited by 8 publications

(3 citation statements)

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“…Asphaltenes have been routinely characterized by vapor-pressure osmometry, − size exclusion chromatography (SEC), ,− low-resolution mass spectrometry, ,− and UV-fluorescence. , However, vapor-pressure osmometry and SEC have been shown to inaccurately represent the molecular weights of asphaltenes because of flocculation and aggregation. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) affords ultrahigh mass resolving power ( m /Δ m 50% > 300 000, in which Δ m 50% denotes mass spectral peak full width at half-height) and high mass accuracy, <1 ppm, for the unambiguous assignment of elemental composition to thousands of components per mass spectrum.…”

Section: Introductionmentioning

confidence: 99%

Mass Spectral Analysis of Asphaltenes. II. Detailed Compositional Comparison of Asphaltenes Deposit to Its Crude Oil Counterpart for Two Geographically Different Crude Oils by ESI FT-ICR MS

et al. 2006

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Asphaltenes are known to deposit in both the petroleum recovery and topside refining processes. The asphaltenes are normally in equilibrium under reservoir conditions. As crude oil is produced, that equilibrium may be disrupted by a number of factors including pressure reductions, crude oil chemical composition changes, introduction of miscible gases and liquids, mixing with diluents and other oils, and, during acid stimulation, hot oiling and other oilfield operations. Electrospray ionization preferentially ionizes polar components of a sample matrix without prechromatographic separation, and its coupling with Fourier transform ion cyclotron resonance mass spectrometry makes a powerful analytical tool for the detailed compositional analysis of petroleum-derived materials such as deposit asphaltenes. In this work, we compare two geographically different crude oils to their corresponding asphaltene deposits. Negative-ion electrospray is preferred because of the acidic nature of asphaltenes. We find that the crude oil deposits contain higher aromatic character (more unsaturated) and are enriched in oxygenated species as well as multiple heteroatom classes compared to their crude oil counterpart. Such a detailed compositional comparison of the deposit asphaltenes to its crude oil counterpart should help to develop more cost-effective methods to control the deposition of asphaltenes and to increase the overall efficiency of the processing fields with asphaltene problems.

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Section: Introductionmentioning

confidence: 99%

Mass Spectral Analysis of Asphaltenes. II. Detailed Compositional Comparison of Asphaltenes Deposit to Its Crude Oil Counterpart for Two Geographically Different Crude Oils by ESI FT-ICR MS

et al. 2006

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“…Determination of the molecular-weight-related properties of asphaltenes is an important step toward the characterization of these substances, and, thus, much effort has been devoted to this goal. − ,, ,, However, because of several factors (such as polydispersity of the sample), difficulties in isolation from crude oils, limitations of techniques used to measure the values, and the tendency to form aggregates, such determinations have been proven to be very difficult. Thus, it is not surprising that molecular weights between 300 000 and 1000 have been reported in the past. , It is now recognized that the major source of these discrepancies is the formation of aggregates or macrostructures formed through intermolecular interactions.…”

Section: Introductionmentioning

confidence: 99%

“…Vapor pressure osmometry (VPO), ,,− ,, size exclusion chromatography (SEC), ,,− , and mass spectrometry (MS) 4-9,17,18,24 are among the techniques most commonly used for molecular weight studies of asphaltenes and bitumen. Because of its simplicity and cost, VPO is used extensively.…”

Section: Introductionmentioning

confidence: 99%

Molecular Weight of Petroleum Asphaltenes: A Comparison between Mass Spectrometry and Vapor Pressure Osmometry

Acevedo¹,

Gutiérrez²,

Negrin³

et al. 2005

Energy Fuels

120

106

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Seven asphaltene samples and six octylated asphaltene (OA) derivatives were analyzed using laser desorption ionization−time-of-flight (LDI−TOF) mass spectrometry (abbreviated as MS) and vapor pressure osmometry (VPO) techniques. Molecular weight distributions (MWDs) that were determined using MS spanned, for all asphaltenes samples and their octylated counterparts, a similar range, from ∼100 Da to ∼10 000 Da. For asphaltenes, the number-average molecular weight (M n ) and weight-average molecular weight (M w ) afforded values in the 1900 ± 200 and 3200 ± 400 intervals, respectively. Consistently heavier values were observed for the OA derivatives (M n ≈ 2300 ± 200 and M w ≈ 3600 ± 200). To select the adequate laser power for these measurements, experiments at different laser powers were performed, to increase volatility and reduce fragmentation to a minimum. Several other experiments were performed to validate these results. First, good agreement between the measured and calculated M n values was observed for OA materials (calculated from asphaltene M n and n, the number of octyl groups introduced, as determined from elemental analysis); second, M n values, as measured by VPO and MS, were determined to be equal, within an average standard deviation of ±27.0%. These results and calculations strongly suggest that the MWD, the molecular weight range, and the molecular weight averages determined using the present MS technique are reasonable estimates of the molecular weight properties of asphaltenes and not the result of artifacts such as fragmentation, polymerization, incomplete volatilization, etc., which may be occurring during the MS experiment.

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Structure‐type separation of diesel fuels by solid phase extraction and identification of the two‐ and three‐ring aromatics by capillary GC‐mass spectrometry

Bundt

Herbel

Steinhart

et al. 1991

J. High Resol. Chromatogr.

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A simple and effective solid phase extraction (SPE) method using silica gel micro glass columns has been developed for the separation of diesel fuel into groups of aliphatic, and mono-, di-, and polyaromatic hydrocarbons. It is based on a stepwise gradient of dichloromethane in n-pentane. The resulting fractions were analyzed by capillary gas chromatography with a flame ionization detector and coupled gas chromatographymass spectrometry.Commercially available standards, and retention indices and mass spectra were used for identification of individual aromatic compounds. The principal polycyclic aromatic hydrocarbons (PAHs) in diesel fuel are naphthalene, biphenyl, fluorene, phenanthrene and their alkylated derivatives. Sulfur-containing PAHs are mainly represented by methyl-substituted dibenzothiophenes.

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HP‐GPC characterization of asphalts

Cited by 8 publications

References 1 publication

Mass Spectral Analysis of Asphaltenes. II. Detailed Compositional Comparison of Asphaltenes Deposit to Its Crude Oil Counterpart for Two Geographically Different Crude Oils by ESI FT-ICR MS

Mass Spectral Analysis of Asphaltenes. II. Detailed Compositional Comparison of Asphaltenes Deposit to Its Crude Oil Counterpart for Two Geographically Different Crude Oils by ESI FT-ICR MS

Molecular Weight of Petroleum Asphaltenes: A Comparison between Mass Spectrometry and Vapor Pressure Osmometry

Structure‐type separation of diesel fuels by solid phase extraction and identification of the two‐ and three‐ring aromatics by capillary GC‐mass spectrometry

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