Asphaltenes: Definition, Properties, and Reactions of Model Compounds

Alshareef, Ali H.

doi:10.1021/acs.energyfuels.9b03291

Cited by 38 publications

(36 citation statements)

References 117 publications

(310 reference statements)

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“…The other common characteristic of the asphaltene samples herein is having the modified Yen−Mullins model structures 14 rather than the archipelago model. 15 On the other hand, one of the major differences is the average size, where sample 1 extracted from a heavy crude oil has smaller size than samples 2 and 3 from light crude oils. 16 The other important difference is the functional groups such as −CO varying from one sample to the other.…”

Section: ■ Introductionmentioning

confidence: 99%

Obtaining Nanoporous Polycyclic Aromatic Hydrocarbon Networks by Cross-Linking Asphaltenes

Samuel

2021

Energy Fuels

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The complexity in the chemical structure of asphaltenes has the potential to be utilized in generating novel materials. In the present study, three different asphaltene samples derived from heavy and light crude oils are cross-linked in a chlorinated solvent. Diffuse reflectance infrared Fourier transform spectroscopy was used for the identification of functional groups and aliphatic-to-aromatic ratios type index values of cross-linked asphaltenes. Raman spectra of asphaltenes showed an increase in average molecular dimensions of cross-linked asphaltenes compared to the original asphaltenes without cross-linking. A porous network-type structure is proposed for explaining the structure of the cross-linked asphaltenes, and this is revealed by surface area analysis. It seems that it is possible to cross-link asphaltenes independent of their geographical origin. The experimental procedure here could be applied for similar materials as well. The cross-linked asphaltenes with porous network-type structure might act as a precursor material for making activated porous carbons, a carbonaceous scaffold for synthesizing novel materials in the confined state, and for modifying surfaces of nanomaterials.

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Section: ■ Introductionmentioning

confidence: 99%

Obtaining Nanoporous Polycyclic Aromatic Hydrocarbon Networks by Cross-Linking Asphaltenes

Samuel

2021

Energy Fuels

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“…There are always solvent or non-asphaltene molecules trapped or occluded in asphaltenes, regardless of how much effort is put into purification; however, at the same time, more and more "asphaltenes" are leaching out or solubilized in the solvent. 8,10,13 Therefore, after reviewing the evolution of the asphaltene definition in "Asphaltenes, What Art Thou? ", Moir pointed out that the concept of "pure" asphaltenes is an oxymoron.…”

Section: Introductionmentioning

confidence: 99%

“…Despite continuous research into the chemical composition and physical properties of asphaltenes over many decades, significant controversies remain. − Since the outcry raised in “Asphaltenes, Where Are You?” by Boduszynski in 1980 that has been reiterated by many papers and reviews since, − it is clear that much of the confusion is caused by the imprecise definition of asphaltene, an ill-defined term based solely on solubility. Asphaltenes are simply the fraction of petroleum insoluble in n -alkanes (usually n -heptane) but soluble in toluene. − In chemistry, solubility is a relative qualifier (high or low), as measured by the saturated concentration of a solute in a solvent, rather than a dichotomous attribute (yes–no, as indicated by soluble or insoluble).…”

Section: Introductionmentioning

confidence: 99%

“…Most asphaltene fractions contain a small amount of inorganic particles (clay) and waxes (paraffins) that are often considered as “impurities” and can be removed by purification, but many studies have shown that no asphaltene is “pure”. There are always solvent or non-asphaltene molecules trapped or occluded in asphaltenes, regardless of how much effort is put into purification; however, at the same time, more and more “asphaltenes” are leaching out or solubilized in the solvent. ,, Therefore, after reviewing the evolution of the asphaltene definition in “Asphaltenes, What Art Thou?”, Moir pointed out that the concept of “pure” asphaltenes is an oxymoron …”

Section: Introductionmentioning

confidence: 99%

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Mechanisms of Asphaltene Aggregation: Puzzles and a New Hypothesis

et al. 2020

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In petroleum science, asphaltenes are well-known as the most refractory fraction of crude oil and remain infamous for problems in production, transportation, and refining processes. Hence, they have been continuously analyzed and modeled over more than half a century. Defined only by solubility and characterized by an extremely complex and diverse molecular composition, asphaltenes lack discriminative molecular descriptions and definitive chemical characteristics. Most of the historic research has focused on representative structures in an attempt to yield physical and chemical models of asphaltenes, and thus, conflicting theories of bonding structures and aggregation interactions remain. This review focuses on the aggregation behavior of asphaltenes and attempts to rationalize a structure−property relationship to asphaltene aggregate thermal stability. Herein, the chemical and physical bonding properties of asphaltenes and the contradictory interpretations of their nature and composition are examined, particularly as they impact formation and stability of asphaltene aggregates. We propose a new hypothesis involving free radical interactions, i.e., pancake bonding, as an additional significant contributor to the bonding structure and formation of aggregates in asphaltenes that is consistent with the latest findings based on Fourier transform ion cyclotron resonance mass spectrometry and non-contact atomic force microscopy techniques. Various structural features of polycyclic aromatic hydrocarbons contributing to this interaction involving a stable free radical are highlighted, and suggestions for future research are presented.

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“…We selected air-stable iron sulfido clusters of known Fe/S ratio, high solubility in hydrocarbon media, and relatively modest thermal stability to ensure efficient formation of an oil-supported nanocatalyst under reaction conditions. Four model compounds (Figure ), which are representative of the small polycyclic aromatic hydrocarbon units dominant in lighter asphaltenes, − were selected for this investigation of catalytic aromatic hydrogenation and hydrodesulfurization.…”

Section: Introductionmentioning

confidence: 99%

Sulfided Homogeneous Iron Precatalyst for Partial Hydrogenation and Hydrodesulfurization of Polycyclic Aromatic Model Asphaltenes

et al. 2020

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Here, we report the first study to use Fe 2 S 2 (CO) 6 as a well-defined petroleum-soluble precatalyst for partial hydrogenation of polycyclic aromatic and heteroaromatic compounds, including pyrene, phenanthrene, naphthalene, and benzothiophene. The in situ-generated heterogeneous catalyst was characterized using a combination of thermogravimetric analysis (TGA), combustion analysis (CHNS), Fourier transform infrared (FT-IR) spectroscopy, scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy-energy dispersive Xray (SEM-EDX). Catalytic performance of Fe 2 S 2 (CO) 6 was evaluated in a batch microreactor coupled with an agitator, varying reaction temperature, pressure, and precatalyst loading. The active phase, consisting of iron sulfide nanoparticles, was prepared from purified Fe 2 S 2 (CO) 6 in toluene; no sulfur additive is required. The results demonstrate that a "presulfided" iron catalyst leads to partial hydrogenation of polycondensed aromatics under moderate conditions, with naphthalene showing only low conversion. Activated carbon, γ-alumina, and activated silica are all effective dispersants for the Fe precursor. The reactivity shows self-consistent substrate dependence, varying with the resonance energy stabilization of the starting compounds and partially saturated intermediates coupled with the surface adsorption enthalpy of the aromatic ring system. The active catalyst derived from this precursor exhibits higher catalytic activity than commercial iron sulfide precatalysts. Importantly, the catalyst is active for hydrodesulfurization (HDS) of benzothiophene, albeit modestly so.

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Asphaltenes: Definition, Properties, and Reactions of Model Compounds

Cited by 38 publications

References 117 publications

Obtaining Nanoporous Polycyclic Aromatic Hydrocarbon Networks by Cross-Linking Asphaltenes

Obtaining Nanoporous Polycyclic Aromatic Hydrocarbon Networks by Cross-Linking Asphaltenes

Mechanisms of Asphaltene Aggregation: Puzzles and a New Hypothesis

Sulfided Homogeneous Iron Precatalyst for Partial Hydrogenation and Hydrodesulfurization of Polycyclic Aromatic Model Asphaltenes

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