In the petroleum industry, the demand for light crude oils is increasing as well as a decrease in oil reserves. One of the alternatives to meet this demand is to process more heavy crude oils, which contains a large number of asphaltenes or transform part of petroleum residues into lighter fractions and products. Asphaltenes are defined as a solubility class of petroleum molecules being soluble in aromatic solvents such as toluene but insoluble in n-alkanes such as n-pentane or n-heptane. This solubility-defined petroleum fraction plays a huge role in water contamination during storage, flow impedance in pipelines, well-bore plugging during oil recovery/transport, etc. Hence, the study and development of efficient methods to solve asphaltenes-related problems will benefit from a molecular-level understanding of asphaltenes composition and structure. A way of studying asphaltenes is through fractionation into several discrete subfractions, which could allow an extended characterization providing further information in its composition as well as into the role of aggregation. In this work, we evaluate the correlation between the solubility and the molecular structure of the subfractions in solvent mixtures of varying polarity. Asphaltenes were obtained from the Chichimene field (Colombia) according to the method described in the ASTM Method D-6560. Then, the fractionation process was based on reprecipitating asphaltenes, where n-heptane and toluene were used as reprecipitating solvents (Heptol). The differences between the fractions of each solvent-precipitant pair provided an insight into the chemical polydispersity of asphaltenes and suggested precipitation mechanisms based on the molecular characteristics of the fractions. The different asphaltene subfractions were evaluated and analyzed by elemental analysis, Fourier Transform Infrared (FTIR), Raman, MALDI-TOF Mass Spectrometry, 1H and 13C Nuclear Magnetic Resonance (NMR).

Approaching to heavy Colombian oil asphaltenes: Extraction, fractionation and structural characterization by spectroscopic techniques

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.