Features of the composition of vanadyl porphyrins in the crude extract of asphaltenes of heavy oil with high vanadium content

Yakubov, M. R.; Milordov, D. V.; Yakubova, S. G.; Borisov, D. N.; Gryaznov, P. I.; Mironov, N. A.; Abilova, G. R.; Borisova, Yu. Yu.; Tazeeva, E. G.

doi:10.1080/10916466.2015.1122627

Cited by 33 publications

(20 citation statements)

References 6 publications

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“…It could be assumed that asphaltenes with a more condensed structure and lower VP content are adsorbed on alumina. It agrees with the previously revealed trend of inverse dependence of the concentration of FR on the content of vanadyl complexes (see papers [19,21,22] and references therein). Alternatively (or additionally), a formation/disappearing of new stable radicals, in which EPR spectra are indistinguishable from the initial ones, as a result, for example, of chemical bond opening/chemical bonding and oxidation processes upon adsorption [60,61], could be supposed.…”

Section: Resultssupporting

confidence: 92%

“…In general, petroleum porphyrins exist in homologous manifolds of several structural classes and can manifest great structural diversity. A series of papers nowadays is devoted to the determination of various vanadyl porphyrins (VP), to application of state-of-the-art massspectroscopic techniques for that purpose as well as to the development of different pathways of the effective vanadyl extraction [1,4,[16][17][18][19][20][21][22][23]. Dickie and Yen were the first to suggest that, having many of the same interactive groups as asphaltenes, petroporphyrins could also play a role in asphaltene self-assembly, adsorption, and phase separation [24].…”

Section: Introductionmentioning

confidence: 99%

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High-Field (3.4 T) ENDOR Investigation of Asphaltenes in Native Oil and Vanadyl Complexes by Asphaltene Adsorption on Alumina Surface

et al. 2019

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Vanadyl porphyrin complexes in asphaltenes from heavy (Karmalinskoye) oil and in asphaltene films obtained as a result of adsorption on the surface of aluminum oxide were studied by electron paramagnetic resonance (EPR) and double electron-nuclear resonance (ENDOR) in the W-band frequency range (microwave frequency of 95 GHz, magnetic field of 3.4 T). Mims ENDOR spectra from 1H and 27Al nuclei are observed. ENDOR spectra are different for native oil and asphaltenes from one side and the adsorbed samples from the other side while no significant changes in X- (microwave frequency of 9 GHz) or W-band EPR spectra are found. The results allow supposing that vanadyl porphyrin complexes (at least in the studied asphaltene films) participate in the formation of asphaltene aggregates through the functional groups rather than π−π interactions. The data show the feasibility of the commercial pulsed ENDOR approaches for the investigation of crude oils and their constituents under external influence.

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

High-Field (3.4 T) ENDOR Investigation of Asphaltenes in Native Oil and Vanadyl Complexes by Asphaltene Adsorption on Alumina Surface

et al. 2019

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“…Other known alterations include cleavage and cyclization or aromatization of side chains and the addition of aromatic and thiophenic rings, oxygen, sulfur, and possibly pendant moieties. 21−23…”

Section: Introductionmentioning

confidence: 99%

Elucidating the Geometric Substitution of Petroporphyrins by Spectroscopic Analysis and Atomic Force Microscopy Molecular Imaging

et al. 2019

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Determination of the molecular structures of petroporphyrins has been crucial to understand the diagenetic pathways and maturation of petroleum. However, these studies have been hampered by their structural complexity and the challenges associated with their isolation. In comparison to the skeletal macrocyclic structures, much less is known about the substitutions, which are more sensitive to the maturation and diagenesis pathways. While these isolated vanadyl petroporphyrins largely consist of etioporphyrin and deoxophylloerythroetioporphyrin as expected, surprisingly, we find evidence that one or a few β hydrogens are present in petroporphyrins of low carbon numbers using a combination of ultraviolet–visible spectroscopy, Fourier transform ion cyclotron resonance mass spectrometry, and non-contact atomic force microscopy. Petroporphyrins with β hydrogens were not anticipated on the basis of their biological precursors. The data support dealkylation under catagenesis but not transalkylation or random alkylation of the β and meso positions, despite the fact that more complex porphyrin structures are formed.

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“…This oil is characterized by the following parameters: density of 0.947 g/cm; sulfur, vanadium, and nickel contents of 4.45, 0.057, and 0.015 wt %, respectively; and resin and asphaltene contents of 34.2, and 11.9 wt %, respectively. The DMF extract of asphaltenes (EA) was isolated from n -hexane asphaltenes of the oil by the method of deposition extraction as described in our previous works. , Its yield was 12.3%. The CHNS elemental compositions of EA were found to be 75.54, 8.42, 2.63, and 4.86%.…”

Section: Experimental Section and Equationsmentioning

confidence: 99%

Impact of Asphaltenes on the Adsorption Behavior of Petroleum Vanadyl Porphyrins: Kinetic and Thermodynamic Aspects

et al. 2021

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In the present work, the first data on the adsorption behavior of petroleum vanadyl porphyrins in the presence and absence of asphaltenes are afforded. As adsorptives, N,N′-dimethylformamide extract of asphaltenes containing 9.88 wt % vanadyl porphyrins and high-purity vanadyl porphyrins preisolated from the extract by the sulfocationite-based chromatographic method were used. As adsorbents, two mesoporous silica gels distinguished in their ability to slow down the rate of diffusion of asphaltene nanoaggregates were chosen. Changes in adsorptive concentration upon adsorbing were monitored spectrophotometrically. Time- and concentration-dependent adsorption studies have been conducted, and particular features in the adsorption behavior of asphaltenes and vanadyl porphyrins have been revealed and used in modeling the intermolecular asphaltene–vanadyl porphyrin interactions occurring inside the adsorbent pores. An adsorption kinetic experiment showed that the asphaltenes diffuse inside the adsorbent pores in the aggregated form and reduce the diffusion rate of vanadyl porphyrins virtually up to the rate of the asphaltene nanoaggregates themselves. An equilibrium adsorption experiment revealed that when a Langmuir-type adsorption happens the asphaltene nanoaggregates adsorbed are composed of 5–8 monomers, which is well consistent with the Yen–Mullins model. No competition for free adsorption sites between asphaltenes and vanadyl porphyrins was observed, which indicates a coaggregation mechanism of vanadyl porphyrin uptake. This assumption was supported by an adsorption thermodynamic study displaying that enthalpy change of adsorption obtained by the van’t Hoff method takes positive values for both the asphaltenes and vanadyl porphyrins present in them (ΔH° > 0) but not for isolated vanadyl porphyrins (ΔH° < 0). An average molecular weight of asphaltene monomers required for thermodynamic calculations was derived from their matrix-assisted laser desorption/ionization (MALDI) mass spectrum mathematically simulated using a log–normal distribution function. The results of the present work contribute to better understanding the nature of asphaltene–petroporphyrin interactions responsible for aggregation and adsorption properties of these petroleum components.

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Features of the composition of vanadyl porphyrins in the crude extract of asphaltenes of heavy oil with high vanadium content

Cited by 33 publications

References 6 publications

High-Field (3.4 T) ENDOR Investigation of Asphaltenes in Native Oil and Vanadyl Complexes by Asphaltene Adsorption on Alumina Surface

High-Field (3.4 T) ENDOR Investigation of Asphaltenes in Native Oil and Vanadyl Complexes by Asphaltene Adsorption on Alumina Surface

Elucidating the Geometric Substitution of Petroporphyrins by Spectroscopic Analysis and Atomic Force Microscopy Molecular Imaging

Impact of Asphaltenes on the Adsorption Behavior of Petroleum Vanadyl Porphyrins: Kinetic and Thermodynamic Aspects

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