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Tracking aging of bitumen and its saturate, aromatic, resin, and asphaltene fractions using high-field fourier transform ion cyclotron resonance mass spectrometry.
Energy Fuels 31, 4771-4779 (2017)
Bitumen is a widely used material, but its aging behavior is only understood at a macroscopic level as hardening and embrittlement over time. To assess bitumen aging behavior in the long run, the pressure aging vessel (PAV) testing procedure was developed. However, this procedure including high-pressure and high-temperature oxidation of the bitumen has not yet been understood on a molecular level. Here, a bitumen sample and its SARA fractions, i.e., saturates, aromatics, resins, and asphaltenes, were investigated in comparison with their aged samples to study changes of their chemical compositions. Negative electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry [ESI(-)] FT-ICR-MS was used to analyze samples. The effect of aging was characterized using the aromaticity equivalent (X-c, double bond equivalent (DBE), and van Krevelen plots. It was found that aging induces reduction of condensed aromatic compounds to alicyclic and open chain aliphatic compounds, while small aromatic compounds have been found to be relatively stable (or altered only slightly). Abundant alterations were detected in unaged bitumen. These changes can be assigned to resins and asphaltenes as compared to saturates and aromatics. Overall, alterations of highly condensed compounds were found to be related to aging. Furthermore, molecular series of CHO, CHNO, and CHOS fragments were more susceptible to oxygenation in bitumen, aromatics, resins, and asphaltenes as compared to saturates. In addition, molecular changes in asphaltenes showed a significant difference from classical assessment with high content of condensed aromatic compounds. Rather, the most abundant compounds in asphaltenes appear to be more saturated and apolar.
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Publication type
Article: Journal article
Document type
Scientific Article
Keywords
Dissolved Organic-matter; Ft-icr Ms; Electrospray-ionization; Crude-oil; Structural-characterization; Elemental Compositions; Nmr-spectroscopy; Sulfur-compounds; Heavy Petroleum; Sara Fractions
ISSN (print) / ISBN
0887-0624
e-ISSN
1520-5029
Journal
Energy & Fuels
Quellenangaben
Volume: 31,
Issue: 5,
Pages: 4771-4779
Publisher
American Chemical Society (ACS)
Publishing Place
Washington
Non-patent literature
Publications
Reviewing status
Peer reviewed
Institute(s)
Research Unit Analytical BioGeoChemistry (BGC)