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

Gafurov, Marat; Mamin, G. V.; Gracheva, I. N.; Murzakhanov, Fadis F.; Ganeeva, Yu. M.; Yusupova, T. N.; Orlinskiĭ, S. B.

doi:10.1155/2019/3812875

Cited by 13 publications

(10 citation statements)

References 62 publications

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“…For example, NV fluorescent centers could be studied by optically detected magnetic resonance; further radiation damage centers or impurity may be created inside the diamond to introduce additional paramagnetic markers into the structure of nanoparticle. From the other hand, the presented results can be used for the investigation of adsorption of magnetic nuclei-containing substances that may be important to study supramolecular structures of oil asphaltenes and − reaction of polymerization in the conditions of spatial/quantum confinement for using ND as catalysts …”

Section: Discussionmentioning

confidence: 99%

Influence of the Chemical Modification of the Nanodiamond Surface on Electron Paramagnetic Resonance/Electron-Nuclear Double Resonance Spectra of Intrinsic Nitrogen Defects

et al. 2019

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A high-frequency/high-magnetic field (94 GHz/3.3 T) electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) study of monocrystalline nanodiamonds (ND) is carried out. Influence of the hydrogen and fluorine modification of the ND surface on EPR and ENDOR signals from the superficial and bulk paramagnetic centers is observed. The effect shows that the ND bulk paramagnetic centers could serve as the intrinsic probe of ND surface modification despite deep localization, shielding from the environment and two-layered surface of the diamond nanoparticle.

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Section: Discussionmentioning

confidence: 99%

Influence of the Chemical Modification of the Nanodiamond Surface on Electron Paramagnetic Resonance/Electron-Nuclear Double Resonance Spectra of Intrinsic Nitrogen Defects

et al. 2019

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“…Some 1–2% of asphaltene molecules contain organic radicals. , Recently, a consortium of academic and industrial researchers postulated that these radicals solve the “puzzle” of asphaltene aggregation . One proposed mechanism involves half-pancake bonds between radical and nonradical PAH.…”

Section: Introductionmentioning

confidence: 99%

“…The relatively low concentration of radicals in asphaltene , rules out pancake bonds between radicals as a major source of aggregation, as the formation of pancake bonds would require the radicals to find each other consistently. Reference instead postulated “half-pancake” bonds between a radical PAH and a nonradical PAH.…”

Section: Introductionmentioning

confidence: 99%

Half-Pancake Bonding in Asphaltenes

Janesko

2021

Energy Fuels

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Aggregation of asphaltenes in petroleum crude oil is a well-known and ongoing problem for petroleum production. Asphaltenes aggregate even in situations where polycyclic aromatic hydrocarbon (PAH) model compounds do not, which implies that there is more to the phenomenon than just π-stacking. Half-pancake bonds involving stable radical PAH have been hypothesized to contribute to asphaltene aggregation (ZhangY. Zhang, Y. Energy Fuels20203490949107). We report density functional theory calculations on half-pancake bonding in asphaltene model compounds. Pancake and half-pancake bonds can be viewed as multi-center generalizations of (common) two-electron covalent bonds and (rare) odd-electron bonds, respectively. In the absence of other effects, we find negligible half-pancake bonding between radical PAH and neutral nonradical PAH. Introducing heteroatoms can produce modestly strong donor-acceptor half-pancake-type interactions. Our results suggest that half-pancake bonding alone is too weak and too rare to drive asphaltene aggregation. However, interactions between stable organic radicals, heteroatoms, and polar groups may contribute to aggregation.

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“…Elucidation of the petroporphyrin structure by ultrahigh-resolution mass spectrometry − and atomic force microscopy could shed light on the processes occurring during oil formation and maturation. Study of petroporphyrin contribution to asphaltene aggregation behavior through electron and electron-nuclear double paramagnetic resonance, , electronic spectroscopy, , small-angle neutron scattering, , size-exclusion chromatography, etc. could provide better insights into the nature of asphaltene–petroporphyrin and asphaltene–asphaltene interactions.…”

Section: Introductionmentioning

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

Cited by 13 publications

References 62 publications

Influence of the Chemical Modification of the Nanodiamond Surface on Electron Paramagnetic Resonance/Electron-Nuclear Double Resonance Spectra of Intrinsic Nitrogen Defects

Influence of the Chemical Modification of the Nanodiamond Surface on Electron Paramagnetic Resonance/Electron-Nuclear Double Resonance Spectra of Intrinsic Nitrogen Defects

Half-Pancake Bonding in Asphaltenes

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

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