NMR imaging studies of asphaltene precipitation in asphalts

Miknis, Francis P.; Pauli, Adam T.; Michon, Laurent C.; Netzel, Daniel A.

doi:10.1016/s0016-2361(98)80030-6

Cited by 24 publications

(13 citation statements)

References 3 publications

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“…The technique is routinely utilized in food science, chemical engineering and materials science. The processes, such as sol–gel transfer, polymerization and cement processes, sedimentation, chemical wave propagation, catalyst materials, and heavy crude oils are successfully studied by MRI. − While MRI methods provide a spatial resolution only in tens of microns but allow study of asphaltenes association, aggregation and precipitation in bulk phases.…”

Section: Application Of Nmr Spectrocopy On Asphaltenesmentioning

confidence: 99%

“…The number of NMR imaging studies − is limited with respect to most of the NMR techniques applied for the analysis of asphaltenes. In particular, the new probes designed for NMR imaging will allow researchers to investigate asphaltene association, aggregation, precipitation, and interfacial properties with better clarity.…”

Section: Lessons Learned and Suggested Future Studiesmentioning

confidence: 99%

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NMR Spectroscopy Analysis of Asphaltenes

Mal

2019

Energy Fuels

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In crude oil production and processing, asphaltene aggregation followed by precipitation is a major problem for the oil industry as it causes deactivation of catalysts, blocking pipelines, and deposition on the internal surface of the reservoirs, etc. Asphaltenes, a complex mixture of a broad distribution of molecules, consisting of aromatic cores bonded to aliphatics and porphyrin type molecules with heavy metals, are defined based on solubility. Molecular complexity along with varying molecular weight distribution makes asphaltenes a difficult scientific problem to characterize. Over several decades, many researchers have contributed to characterization, analysis, and determination of structural properties of asphaltenes by various analytical techniques. Nuclear magnetic resonance (NMR) spectroscopy and relaxometry are widely applied for characterizing the chemical structures of asphaltenes, interactions between asphaltenes and maltenes, and dynamical behaviors of asphaltenes in bulk and in confined states. The goal of the current review article is to give an insight into various aspects of asphaltene analysis by NMR spectroscopy and relaxometry. Following a short introduction on asphaltenes and theory of NMR technique, recent contributions on asphaltenes by NMR techniques are summarized and presented. Lessons learned and suggestions on possible future work conclude the present review article.

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Section: Application Of Nmr Spectrocopy On Asphaltenesmentioning

confidence: 99%

Section: Lessons Learned and Suggested Future Studiesmentioning

confidence: 99%

NMR Spectroscopy Analysis of Asphaltenes

Mal

2019

Energy Fuels

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“…However, the reversibility phenomenon in a certain sense contradicts previous observations. Investigation of iso -octane/asphalt solution in toluene blends revealed the formation of the prominent interfacial deposit containing spherical globules . This deposit layer was not prone to reversible dissolution, and normal asphaltene precipitation followed by sediment accumulation on the bottom was clearly observed simultaneously with the interface layer.…”

Section: Resultsmentioning

confidence: 97%

“…The main advantages of MRI stem from the fact that the NMR signal is very sensitive to small alternations of the chemical composition and/or physical structure of the systems under study. Thus, MRI is a well-known noninvasive visualization technique that has successfully been applied in many areas of research such as materials science, chemical engineering, petroleum science, − etc. Recently, MRI proved to be a very informative tool for studying the phase behavior of heavy constituents in crude oils. − …”

Section: Introductionmentioning

confidence: 99%

Reversibility of Asphaltene Aggregation As Revealed by Magnetic Resonance Imaging in Situ

Morozov

Martyanov

2017

Energy Fuels

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Aggregation of asphaltenes followed by precipitation presents severe problems for existing technologies in the production, recovery, and processing of heavy oils. Better understanding of asphaltene behavior behind the processes of their precipitation and dissolution is vital to address this issue. While investigating the inhomogeneity of different oil systems, the reversibility of the asphaltene aggregation process initiated by flocculant in either asphaltene solution in toluene or crude heavy oil was revealed and investigated using magnetic resonance imaging methods. It was found that the inhomogeneous distribution of the flocculant initiates local spatial-selective asphaltene aggregation registered in a thin layer around the flocculant/oil sample interface. The local excess of flocculant concentration over the threshold of asphaltene precipitation onset is a driving force of this process. As the flocculant diffuses into the volume of the sample, a decrease of the asphaltene flocculated area is observed until it disappears when the equilibrium composition throughout the whole volume of the system is achieved. Depending on the overall flocculant concentration, the asphaltene aggregation may not be reversible and could be followed by subsequent precipitation of the asphaltene aggregates. The similarity of the phenomena observed for the model asphaltene solutions and crude heavy oil samples was established. Partial mechanical stirring of the multicomponent system comprising flocculant and oil or asphaltene solution does not prevent the formation of the local zones with increased concentration of asphaltene aggregates; those sizes evolve depending on the flocculant concentration. The results obtained in this work are consistent with the generally accepted concept of asphaltene precipitation reversibility depending on the system composition and are compatible with the observations obtained by other methods. The approach presented can provide deeper insight into the asphaltene precipitation reversibility issue and can facilitate the understanding of asphaltene behavior in heavy oils.

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“…MRI provides spatial resolution of 10 μm, which allows the study of the systems at the micrometer level to obtain unique in situ data on the phase stability and physico-chemical processes in real oil samples under different external conditions at different space and time scales. MRI has been used in the studies of aggregation [24], precipitation [25], and segregation [26] of asphaltenes; formation of gas voids [27] and multilayer deposits of paraffin [24] in paraffinrich oil; rheology of heavy oils and model systems [26]; reversibility of certain processes involving asphaltenes depending on their local environment [24].…”

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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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NMR imaging studies of asphaltene precipitation in asphalts

Cited by 24 publications

References 3 publications

NMR Spectroscopy Analysis of Asphaltenes

NMR Spectroscopy Analysis of Asphaltenes

Reversibility of Asphaltene Aggregation As Revealed by Magnetic Resonance Imaging in Situ

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

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