Asphaltene aggregation from vacuum residue and its content of inorganic particles

A. C. Sánchez Berna, V. Camacho Moran, E. T. Romero Guzmán, M. José Yacamán

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Heavy organics deposition from asphaltene flocculation can be controlled through better knowledge of mechanisms that cause depositions. Changes in temperature can influence the thermodynamic equilibrium of vacuum residue and cause asphaltene deposition. The chemical description is very useful for classifying crude oils and is important in the context of catalytic conversion. The high asphaltene concentration in some fractions such as vacuum residue is responsible for many problems encountered during production, transportation, and refining processes. A detailed examination of the literature on asphaltene characterization shows that the major studies that have been carried out concern chemical characterization. Nevertheless, it seems that this information is not sufficient to explain some frequently observed unusual behaviors. For these reasons, the aim of this work was to investigate the colloidal structure of asphaltene aggregates by electron microscopy to study the vacuum residue stability. The stability is governed by local interaction forces and is strongly influenced by the chemistry of the molecules. Asphaltenes from Mexican Maya crude oil were precipitated from vacuum residue during 1 hr of agitation using n-heptane at different temperatures. After this treatment, the asphaltenes were washed using a soxhlet extraction system during 24 hr to remove maltene fraction. A microstructural and elemental characterization of the asphaltenes was realized using scanning electron microscopy (low vacuum) and X-ray energy dispersive spectrometry (EDS). According to the results, the asphaltene organization can be described by different entities: aggregates, sheets, and distributed inorganic particles around the material's bulk. Two morphologies were observed: one is conformed by a compact structure, while the second is conformed by a porous structure. The main asphaltene components are based on carbon and sulfur. The presence of irregular metallic particles of different composition and several nanometers of size distributed principally over the compact structure can also be observed. These inorganic particles are primarily constituted by sodium, calcium, iron, aluminum, chromium, potassium, vanadium, silicon titanium, nickel, magnesium, copper, phosphorus, and chlorine. The analysis of these elements is important because they could have a relevant role in the asphaltenes' aggregation. The reaction yield is 26.13 0.63 for asphaltene precipitated at room temperature and 21.55 0.86 for asphaltene obtained at 98°C.

Original languageEnglish (US)
Pages (from-to)1055-1066
Number of pages12
JournalPetroleum Science and Technology
Issue number9
StatePublished - Sep 1 2006
Externally publishedYes


  • Aggregation asphaltenes
  • Inorganic particles
  • Scanning electron microscopy
  • Vacuum residue

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Geotechnical Engineering and Engineering Geology


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