Behavior of paramagnetic particles in crude oils from west Kazakhstan

Nasirov, R. N.; Солодовников, С. П.

doi:10.1007/bf00728027

Cited by 2 publications

(4 citation statements)

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“…According to the EPR analysis data (Table ), the concentration of free radicals (R*) increases in the asphaltenes of the experiments’ products, whereas the concentration of tetravalent vanadium (V +4 ), the latter being a part of the vanadyl–porfyrin complexes, decreases and the values of the R*/V +4 indicator grow as well . This is also consistent with the changes in the values of others above-mentioned indicators, confirming that the destructive processes with the substance effect on the of asphaltenes structure take place.…”

Section: Resultssupporting

confidence: 78%

“…According to the EPR analysis data (Table 4), the concentration of free radicals (R*) increases in the asphaltenes of the experiments' products, whereas the concentration of tetravalent vanadium (V +4 ), the latter being a part of the vanadyl−porfyrin complexes, decreases and the values of the R*/V +4 indicator grow as well. 31 This is also consistent with the changes in the values of others above-mentioned indicators, confirming that the destructive processes with the substance effect on the of asphaltenes structure take place. The following peculiarity has been observed: carben−carboids (fraction B) from the experiment 2 products and the experiment 3 coke from are characterized by the biggest content of the paramagnetic centers and, accordingly, by bigger values of the R*/V +4 indicator, which is coherent with the highest degree of their aromaticity.…”

Section: Energy and Fuelssupporting

confidence: 88%

“…This alone is in a good agreement with the results received with the help of other physical and chemical methods. This is confirmed by the changes in their molecular masses (Figure ) received by the MALDI method, EPR analysis (Table ) data, as well as by the changes in the asphaltenes structural-group composition determined by the IR spectroscopy …”

Section: Resultssupporting

confidence: 58%

“…The EPR spectra of asphaltenes were taken using the EPR spectrometer SE/X-2544 (Radio PAN, Poland). Two types of signals were registered: a single symmetric signal of R* free stable radicals ( g = 2.003) and the multicomponent superthin structure (STS) corresponding to V 4+ ions, a part of the vanadyl–porfiryn complexes structure . The obtained values of intensity of the corresponding curves in the EPR spectra were normalized in accordance with the sample weight, getting the R* and V 4+ content in relative units.…”

Section: Methodsmentioning

confidence: 99%

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Changes of Asphaltenes’ Structural Phase Characteristics in the Process of Conversion of Heavy Oil in the Hydrothermal Catalytic System

Kayukova¹,

Gubaidullin²,

Петров³

et al. 2016

Energy Fuels

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The composition of heavy crude oil from the Ashal’cha field (Volga-Ural Basin, Republic of Tatarstan) and the peculiarities of the changes of its asphaltenes’ structural phase characteristics in the model hydrothermal–catalytic system have been studied very thoroughly. It has been established that in the water vapor media the process of destruction of the heavy crude oil high-molecular-weight components with the new light fraction formation in the presence of a natural catalyst, namely, hematite, containing iron oxide and at the temperatures of 210, 250, and 300 °C respectively, takes place which has an effect on the changes in its component hydrocarbon, fractional, and structural group composition as well as in the structural parameters of its asphaltenes. As the experiments temperature increases and the water content in the reaction system decreases, the general tendency of growth the asphaltene associates aromaticity factor revealed that in turn it is accompanied by the extension (increase) of the distance between the aromatic layers and polymethylene chain fragments under the reduction of the size of associates and the number of their aromatic layers; this results from the destructive processes course, taking place along/on the most stable asphaltene heteroatomic bonds with/accompanied by further peripheral alkyl fragments breaking off, which has been confirmed by the molecular mass of the fragments above as well as destruction of vanadyl–porphyrin complexes and increase of free radicals concentration. A significant ability of asphaltene associates to immobilize their maltenes has been revealed. Within the process of oxidation cracking at the temperature of 300 °C and under the low water content in the reaction system, the increase in aromaticity and in the degree of association asphaltenes transform to carben–carboids and then to coke and are precipitated out of the oil in the solid form.

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Section: Resultssupporting

confidence: 78%

Section: Energy and Fuelssupporting

confidence: 88%

Section: Resultssupporting

confidence: 58%

Section: Methodsmentioning

confidence: 99%

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