The processes of aggregation and dissolution in model systems resin-asphaltene by NMR

Ivanov, D.; Barskaya, E. E.; Skirda, V. D.

doi:10.26907/mrsej-19202

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“…In spite of the increase in resin concentration in relation to the asphaltene/resin proportions of 7.1, 7.2 and 7.3 wt %, the D rel value for the asphaltene proportion of 2:1 wt % is higher than that of 1:1 wt %. Ivanov et al (2019) 44 showed the presence of asphaltene/resin particles as well as the resin particles in bulk. This behavior can explain that there is a limit for the resin concentration to act like a surfactant on the asphaltene aggregates.…”

Section: Resultsmentioning

confidence: 99%

“…29 This implies that the viscosity values greatly influence D rel values. Ivanov et al (2019) 44 observed that the macro-and microviscosities of resins affect the asphaltene aggregates formation. With the addition of resins, the concentration of suspended solids increases, which suggests that the mobility of solutes is even more limited and the viscosity of the solution is consequently increased.…”

Section: Resultsmentioning

confidence: 99%

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Study of the Influence of Resins on the Asphaltene Aggregates by ¹H DOSY NMR

et al. 2020

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Aggregation and precipitation of asphaltenes are relevant concerns during the extraction and processing of petroleum because of the severe damage they cause to the equipment for crude oil transportation. Studies show that the presence of resins can contribute to smaller aggregate formation and thereby reduce the asphaltene precipitation. Herein, we showed the investigation of the influence of resins on the size of asphaltene aggregates by diffusion-ordered spectroscopy (DOSY). The asphaltenes were extracted from crude oil by precipitation with n-heptane. The resins were extracted from the maltene fraction, and their samples were analyzed by 1H and 13C nuclear magnetic resonance spectroscopy. Aromatic and aliphatic hydrogen and carbon contents were estimated, including their subdivisions. From these results, we estimated the aromaticity factor (f a), the number of naphthenic rings (R N), the number of total rings (R T), the average length of alkyl chains (N alk), the aromatic condensation index (Φ), and the aromatic condensation degree (ξ), which were used to determine the asphaltene architecture. The asphaltene chemical structures were suggested for each sample (asphaltene 1 was predominantly continental, while asphaltenes 2 and 3 were archipelago), and the relative diffusion of asphaltene aggregates and resins in toluene-d 8 was determined by DOSY. Asphaltenes, resins, and their mixtures were prepared in toluene-d 8 at concentrations ranging from 5 to 7 wt %. The aspthaltenes/resins mixture proportions were 7:1; 7:2; 7:3; 1:1; and 2:1 wt %. Generally, the relative diffusion values of the solutions increased because of the addition of resins (asphaltenes/resins 7:3 > 7:2 > 7:1 wt %), indicating that their presence favors the formation of smaller aggregates.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%