Molecular size determination of coal-derived asphaltene by fluorescence correlation spectroscopy

A. Ballard Andrews, Wei Chuan Shih, Oliver C. Mullins, Koyo Norinaga

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


The molecular properties of asphaltenes have been the subject of uncertainty in the literature; in particular the molecular architecture is still a matter of debate. Some literature reports provide evidence that the contrast of petroleum asphaltenes versus coal-derived asphaltenes is useful for understanding the governing principles of asphaltene identity. Here, we employ fluorescence correlation spectroscopy to measure the diffusion constants of asphaltenes obtained from the distillation resid from coal liquefaction fluids. Concentrations employed herein are ̃10-8 molar, precluding asphaltene aggregation. These are compared with the same measurements on petroleum asphaltenes. These results confirm that the molecular sizes of these coal-derived asphaltenes are much smaller than virgin petroleum asphaltenes. Coal-derived asphaltenes are simpler than petroleum asphaltenes and provide correspondingly tighter constraints for understanding asphaltene molecular architecture. The small size, small alkane fraction, and large PAH of coal-derived asphaltenes are consistent with an "island" molecular architecture.

Original languageEnglish
Pages (from-to)1348-1356
Number of pages9
JournalApplied Spectroscopy
Issue number12
Publication statusPublished - 2011

All Science Journal Classification (ASJC) codes

  • Instrumentation
  • Spectroscopy


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