Heavy Petroleum Composition. 3. Asphaltene Aggregation
详细信息 查看全文
- 作者：Amy M. McKenna ; Lynda J. Donald ; Jade E. Fitzsimmons ; Priyanka Juyal ; Victor Spicer ; Kenneth G. Standing ; Alan G. Marshall ; Ryan P. Rodgers
- 刊名：Energy & Fuels
- 出版年：2013
- 出版时间：March 21, 2013
- 年：2013
- 卷：27
- 期：3
- 页码：1246-1256
- 全文大小：484K
- 年卷期：v.27,no.3(March 21, 2013)
- ISSN：1520-5029
文摘
Molecular characterization of asphaltenes by conventional analytical techniques is a challenge because of their compositional complexity, high heteroatom content, and asphaltene aggregate formation at low concentrations. Thus, most common characterization techniques rely on bulk properties or solution-phase behavior (solubility). Proposed over 20 years ago, the Boduszynski model proposes a continuous progression in petroleum composition (molecular weight, structure, and heteroatom content) as a function of the atmospheric equivalent boiling point. Although exhaustive detailed compositional analysis of petroleum distillates validates the continuum model, the available compositional data from asphaltene fractions supports the extension of the continuum model into the nondistillables only indirectly. Asphaltenes, defined by their insolubility in alkane solvents, accumulate in high-boiling fractions and form stable aggregate structures at low parts per billion (ppb) concentrations, far below the concentration required for most mass analyzers. Here, we present direct mass spectral detection of stable asphaltene aggregates at lower concentrations than previously published and observe the onset of asphaltene nanoaggregate formation by time-of-flight mass spectrometry (TOF鈥揗S). We conclude that a fraction of asphaltenes must be present as nanoaggregates (not monomers) in all atmospheric pressure and laser-based ionization methods. Thus, those methods access a subset of the asphaltene continuum.