Characterization of Functional Groups of Asphaltenes in Vacuum Residues Using Molecular Modelling and FTIR Techniques

Coelho, Roberto Rodrigues; Hovell, Ian; Moreno, Esteban Lopez; Souza, André Lopes de; Rajagopal, Krishnaswamy

doi:10.1080/10916460601054198

Cited by 25 publications

(14 citation statements)

References 17 publications

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“…In relation, the IR spectra of eqCRO-aged calcite present distinct aliphatic and aromatic C–H stretching bands in the range of 2800–3100 cm –1 . As summarized in Table S6, the peak positions correspond to the symmetrical and asymmetrical stretching of the aromatic and aliphatic hydrogens, representative of asphaltenic molecules . In summary, the results of Raman and IR spectroscopy show that multiple organic species such as graphitic hydrocarbons and polar molecules contribute to the surface modification of calcite by reservoir pertinent fluids (Table ).…”

Section: Results and Discussionmentioning

confidence: 92%

Mineral Interfaces and Oil Recovery: A Microscopic View on Surface Reconstruction, Organic Modification, and Wettability Alteration of Carbonates

Rao¹,

Kumar²,

Annink³

et al. 2020

Energy Fuels

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While it is generally known that aging protocols have an important impact on the interaction between crude oil (CRO), brines, and mineral surfaces, the microscopic consequences of the various steps of aging have hardly been described. In this study, we characterize the properties of fluids and carbonate mineral surfaces throughout a series of equilibration steps at 95 °C and correlate these microscopic observations with macroscopic contact angle measurements. Chemical equilibration of CRO (eqCRO) and FW (eqFW) leads to transfer of organic molecules from the former to the latter, causing also a pH change in the eqFW. Confocal Raman microscopy, atomic force microscopy, and infrared spectroscopy are used to reveal how consecutive aging of calcite in eqFW and eqCRO induces: first, in eqFW, considerable surface reconstruction and precipitation of mineral particles with colocalized organic species, and second, upon exposure to eqCRO, the formation of a second adlayer primarily composed of polyaromatic hydrocarbon-rich particles. Our results show how these interconnected microscopic chemical and topographical surface modifications give rise to more "oil wetting" contact angles after the two-step aging procedure.

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Section: Results and Discussionmentioning

confidence: 92%

Mineral Interfaces and Oil Recovery: A Microscopic View on Surface Reconstruction, Organic Modification, and Wettability Alteration of Carbonates

Rao¹,

Kumar²,

Annink³

et al. 2020

Energy Fuels

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“…OPUS software (version 6.5) from Bruker was used to correct the base lines, determine the absorbance at specific wavenumbers, and integrate the areas between wavenumbers. The wavenumbers used in determining the functional groups in asphaltenes are reported in the literature. − The FTIR spectra were analyzed by comparing the ratios of intensities and/or the ratios of integrated areas within the same spectrum, and not between the spectra of different samples. Thus, our discussion is based on ratios and relative values, not on absolute quantitative values.…”

Section: Methodsmentioning

confidence: 99%

“…Many studies utilized the FTIR spectroscopic technique to study asphaltene molecules. − Coelho et al studied the linear relationship between the intensity ratios at 2927 and 2957 cm –1 and the ratios of n CH 2 / m CH 3 for carbon chains of alkyl-benzene to determine the aliphatic chains of asphaltenes and resins. They proposed a methodology for determining the functionality and calculating the percentage of single and paired hydrogen atoms attached to aromatic rings for asphaltene and resin . Another methodology was proposed for characterizing the functionality of organic sulfur compounds in asphaltenes by combining quantum chemistry, IR spectra, and deconvolution methods .…”

Section: Introductionmentioning

confidence: 99%

Impact of Thermal Treatment on Asphaltene Functional Groups

et al. 2016

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The main objective of this study is to provide an in-depth analysis that reveals the impact of thermal treatment on the different functional groups that exist in asphaltene molecules. This contribution is important to further understand the nature of changes that take place in asphaltenes during distillation and thermal cracking processes. A slight increase was observed in the aromatic −CH groups, compared to aliphatic −CH groups, as crude oil is processed to atmospheric and vacuum residues. A slight decrease was also observed in the intensity ratio between methylene and methyl groups (CH 2 /CH 3 ) with distillation, which suggests a decrease in the average length of alkyl side chains for asphaltene molecules. The Fourier transform infrared (FTIR) results also suggest the possibility of thiophenic compounds oxidation during the atmospheric and vacuum distillations. More obvious differences were noted between asphaltenes exposed to thermal cracking, separated from the pitch samples, and their parent asphaltenes from the vacuum residues. Although the spectra of thermally treated asphaltenes have most of the features that belong to their parent asphaltenes, the results illustrate more aromatic structures as the reaction severity increases. In addition, the ratio of CH 3 to CH 2 groups shifted toward CH 3 with increasing reaction time and/or temperature due to the shortening of alkyl side chains. FTIR results have been further supported by 1 H and 13 C nuclear magnetic resonance (NMR) analysis, which confirmed the conclusion that thermal cracking of residual oils mainly affected the paraffinic side chains while the observed changes in the aromatic core appear to be relatively limited.

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“…The original studies on the application of IR spectroscopy published more than 20 years ago have unambiguously demonstrated the correlation of chemical composition of asphaltenes with the oil origin [28][29][30][31][32][33]. Prof. S. Kazarian [34] was the first to use FTIR spectroscopy with matrix detection under the attenuated total reflection (ATR) conditions to investigate the asphaltenes aggregation.…”

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confidence: 99%

Chemical Heterogeneity of Deposits Formed in the Flocculant Flow From Crude Oil, According to FTIR Microscopy and Chemical Imaging

et al. 2021

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Asphaltene-containing deposits formed on the CaF2 window induced by n-heptane flow in a microfluidic device have been investigated using an IR microscope and an imaging macro chamber (IMAC) with FPA detection. This is the first example of the ex situ infrared imaging of the deposits from crude oil formed under dynamic conditions of flocculant flow. It has been shown that fast aggregation of asphaltenes in n-heptane flow leads to the formation of deposit rich in heteroatom-containing functional groups: (О–Н, N–H, C=O, C–O, and S=O).

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Characterization of Functional Groups of Asphaltenes in Vacuum Residues Using Molecular Modelling and FTIR Techniques

Cited by 25 publications

References 17 publications

Mineral Interfaces and Oil Recovery: A Microscopic View on Surface Reconstruction, Organic Modification, and Wettability Alteration of Carbonates

Mineral Interfaces and Oil Recovery: A Microscopic View on Surface Reconstruction, Organic Modification, and Wettability Alteration of Carbonates

Impact of Thermal Treatment on Asphaltene Functional Groups

Chemical Heterogeneity of Deposits Formed in the Flocculant Flow From Crude Oil, According to FTIR Microscopy and Chemical Imaging

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