Interactions of Asphaltene Subfractions in Organic Media of Varying Aromaticity

Abstract

Whole asphaltenes were fractionated by extended-saturates, aromatics, resins and asphaltenes (E-SARA) analysis into four asphaltene subfractions: toluene-extracted interfacially active asphaltenes (T-IAA), toluene-extracted remaining asphaltenes (T-RA), heptol 50/50-extracted interfacially active asphaltenes (HT-IAA), and heptol 50/50extracted remaining asphaltenes (HT-RA). The aggregation kinetics of fractionated asphaltenes measured by dynamic light scattering (DLS) showed that decreasing solvent aromaticity promoted asphaltene aggregation for all subfractions. In a given solvent, T-IAA exhibited the strongest aggregation tendency, followed by HT-IAA, then T-RA and

Characterization of the Interfacial Material in Asphaltenes Responsible for Oil/Water Emulsion Stability

“…This observation is very important and indicates that IM molecules have a different aggregation behavior than regular asphaltenes, which form spherical clusters of nanoaggregates. 43 This is in agreement with recent studies where the acidic groups of IM strongly affected their aggregation propensity 44 and mechanism, resulting in larger and less compact aggregate structures. 45 At the o/w interface, IM molecules position themselves in the oil phase, perpendicularly to the interface with their chains protruding toward the water phase, similar to naphthenic acids.…”

Understanding Asphaltene Fraction Behavior through Combined Quartz Crystal Resonator Sensor, FT-ICR MS, GPC ICP HR-MS, and AFM Characterization. Part I: Extrography Fractionations

“…The compositional range of S-containing compounds reveals abundant low-DBE species with higher content of CH 2 groups (longer homologous series), in particular, for the most polar extrography fraction (Tol/THF/MeOH). Previous reports by Chacon-Patiño, Xu, , Kilpatrick, , and Stanford , suggest the existence of asphaltene molecules with low aromaticity or low DBE but high heteroatom content. In particular, Xu et al highlighted that “atypical” S-containing species with low aromaticity could be sulfoxides (RSO), which can participate in hydrogen bonding .…”

“…At the nanoscale level, atomic force microscopy (AFM) is an interesting technique that offers access to three-dimensional information. For asphaltene characterization, AFM has been applied from single asphaltene molecule imaging (Schuler et al) , to observation of asphaltene aggregates in different media/support. − Therefore, AFM is a technique of choice for observation and comparison of the type and form of macroaggregates deposited on metal surfaces or sensors.…”

Interfacial Tension of the Water-Diluted Bitumen Interface at High Bitumen Concentrations Measured Using a Microfluidic Technique

“…To get the bulk molar concentration of asphaltenes, we use C ∞ = w/M w . It is known that only about 4 wt % of total asphaltenes are highly interfacially active in solvents, Heptol 50/50 and Heptol 70/30. , The average molecular weight of interfacially active asphaltenes has been measured to be about 750 Da . Assuming a density of 1000 kg/m 3 , a diffusivity of 10 –10 m 2 /s for 33 wt % bitumen, , and the diffusivity to be inversely proportional to the oil solution viscosity (based on the Stokes-Einstein-Sutherland formula), we calculated the diffusion time scales for the different solutions used in the experiments.…”