Interfacially active asphaltenes were extracted from emulsified crude oils using toluene to remove bulk oil components and loosely attached asphaltenes. The interfacially active asphaltenes were split into two fractions: a more-soluble fraction and a less-soluble fraction. Previously, the different interfacially active solubility fractions were characterized by a variety of methods including Fourier transform ion cyclotron resonance mass spectroscopy (FT-ICR MS), Fourier transform infrared spectroscopy (FT-IR), elemental analysis, ultraviolet-visible spectroscopy (UV-Vis), fluorescence spectroscopy, viscosity, thermogravimetric analysis (TGA), and interfacial tension (IFT). We report further characterization of the different interfacially active solubility fractions by laser desorption ionization mass spectroscopy (LDI MS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). In addition to further characterization, some mechanistic aspects of asphaltene interfacial activity were investigated. One of the most invoked mechanisms for the participation of interfacially active asphaltenes at the oil and water interface is H-bonding. It is assumed that the H-bonding character of asphaltenes which accumulate at oil and water interfaces is stronger compared to less interfacially active asphaltenes. To better understand the H-bonding character, the asphaltenes were subjected to mild methylation of OH functional groups and H-bonding experiments were performed with phenol. These experiments did show a significant difference in the H-bonding character between the whole asphaltenes and the most interfacially active asphaltenes extracted from emulsions for the same crude oil source.

Characterization and behavior of interfacially active asphaltenes from crude oil

253rd National Meeting (2017)

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