Svetlana G. Yakubova

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

ABSTRACT Features of changes in the content of nickel and vanadium in heavy oils and their asphaltenes are shown for various fields of Volga-Ural region (Russia). The change in the content of vanadyl complexes in the studied asphaltenes upon increase of vanadium content was demonstrated. Several polar solvents (acetone, N,N-dimethylformamide, isopropanol, acetonitrile) are compared as extractants to obtain crude extracts of vanadyl porphyrins from asphaltenes with vanadium content of 0.44 wt%. The opportunity of more efficient extraction of vanadyl porphyrins from asphaltenes is shown by deposition extraction method, particularly when using N,N-dimethylformamide. Absorption spectra and matrix-assisted laser desorption/ionization (MALDI) mass spectra of the extracts obtained were analyzed. For extracts with maximum content of vanadyl porphyrins, the presence of mainly etio- and deoxophylloerythroetioporphyrins was revealed. It was shown that proportion of etio-type vanadyl porphyrins does not exceed 75% of the amount of porphyrins of DPEP-type. A maximum of molecular weight distribution in both types falls on a homologue of vanadyl porphyrin C31 containing nine carbon atoms in the alkyl substituents.

Concentrations of Vanadium and Nickel and Their Ratio in Heavy Oil Asphaltenes

Trends in the vanadium and nickel concentrations in asphaltenes of heavy oils from different oilfields, in which the total content of these metals vary from 0.0049 to 0.1795 wt %, have been studied. It has been shown that as the vanadium and nickel content in heavy oils increases, vanadium concentrates faster than nickel in asphaltenes. In heavy oils, asphaltenes contain approximately 40–90% of total vanadium and 25–75% of total nickel. The summed concentration of vanadium and nickel in heavy oil asphaltenes can reach 1 wt %.

Vanadium and paramagnetic vanadyl complexes content in asphaltenes of heavy oils of various productive sediments

ABSTRACT Using the atomic absorption spectrometry and electronic paramagnetic resonance techniques, we have investigated the features of vanadium and vanadyl complexes content in asphaltenes of heavy oils of Permian and Carboniferous productive sediments in the Volga-Ural oil and gas basin deposits. The investigation has been carried out using the heavy oils example, where the asphaltene content ranges from 5.1 to 21.2 wt%, and vanadium content varies in the range of 0.009–0.165 wt%. The specificity of asphaltene–vanadium relationship has been found for heavy oils of various productive sediments. It has been demonstrated that vanadium and vanadyl complexes content in asphaltenes of heavy oils in separate productive sediments varies in the certain range limits.

Sulfuric Acid Assisted Extraction and Fractionation of Porphyrins From Heavy Petroleum Residuals With a High Content of Vanadium and Nickel

Primary porphyrin extracts were obtained from carbon tetrarchloride solutions of different heavy oil residuals with assistance of sulfuric acid. According to data of chromatographic separation of extracts porphyrinic fractions appear in amount of 13.0–24.2%. Based on UV/visible absorption spectroscopy the presence of porphyrins of etio and phyllo types mostly with rhodo and deoxophylloerythroetioporphyrins in lower amount was established. The content of porphyrins in obtained fractions was determined at the level of 15.3–44.8% of the total weight. It was shown that a higher concentration of porphyrins in sulfuric acid extracts occurs for the case of the high vanadium and nickel content and low amounts relation of asphaltenes to resins.

Structural-group composition and properties of heavy oil asphaltenes modified with sulfuric acid

ABSTRACT Details of the change of structural-group composition of heavy oil asphaltenes modified with sulfuric acid and oleum depending on the process conditions have been determined. The effect of the amount and concentration of sulfuric acid, exposure time, and elevated pressure has been evaluated. The formation of sulfo-, sulfono-, phenolic hydroxyl, carboxylic, and carbonyl functional groups has been detected in Fourier transform infrared (FTIR) spectra for the obtained sulfonated asphaltenes. Spectral coefficients have been calculated for asphaltenes and products of their sulfonation according to the main absorption bands in FT-IR spectra. Analysis of spectral coefficients has indicated the relationship of the fraction of newly formed functional groups in sulfonated asphaltenes and process conditions of sulfuric acid modification. The obtained sulfonated asphaltenes have been analyzed as sulfocationites with the evaluation of sorption capacity. It has been shown that the successive modification of heavy oil asphaltenes with sulfuric acid and oleum gives sulfocationite with the static exchange capacity of 3.39 meq/g. The relationship of spectral coefficients and sorption characteristics of sulfonated asphaltenes has been determined.

Differentiation of heavy oils according to the vanadium and nickel content in asphaltenes and resins

The features of the distribution of vanadium and nickel between asphaltenes and resins have been revealed using heavy oils from Tatarstan and Samara oblast oilfields as an example. It has been shown that depending on the V and Ni content in asphaltenes and resins, heavy oils of different productive plays are divided into two separate groups. An increase in the V or Ni content of heavy oils is accompanied by an increase in the concentration of the respective metal in asphaltenes and resins. The intervals of variation in the V and Ni content of asphaltenes and resins of the oils attributed to each group have been determined. As the V concentration in asphaltenes increases, the V/Ni ratio also increases, a feature that is not characteristic of resins.

Thermal stability and sorption properties of asphaltene sulfocathionites

Abstract Using simultaneous thermogravimetry and differential scanning calorimetry, thermal stability and possible phase transitions of asphaltene sulfocationites and native asphaltenes have been evaluated; the kinetic characteristics of heating have been determined, namely, onset temperature of decomposition, stages of decomposition, and temperature ranges of stability. It has been determined that asphaltene sulfocationites retain structural-group features (IR spectroscopy method) and sorption characteristics while heating up to 350 °C.

Relationship of Light Absorption and Vanadium Content in Asphaltenes and Resins of Heavy Oils

Abstract The relationship of the light absorption of asphaltenes and resins with vanadium content has been investigated on the example of heavy oils of various deposits. In the oils of various deposits in Permian and Carboniferous producing complexes of Volga–Ural oil-and-gas bearing basin, the asphaltene content varies from 5.3 to 21.2 wt %, while the vanadium content is from 0.009 to 0.165 wt %. It has been shown that there is a direct correlation of the light absorption of asphaltenes and vanadium content with the correlation coefficient of higher than 0.96 in the case of each producing complex. There is also a direct relationship between the light absorption of resins and vanadium content in the HOs under study with the correlation coefficient of higher than 0.92 in the case of each producing complex.

Effect of oxyethylated isononylphenol (neonol) on viscosity characteristics of water–oil emulsions

Abstract The effect of oxyethylated isononylphenol (AF 9-10 neonol) on the rheology of natural water–oil emulsions has been investigated. It was determined that paraffins and asphaltenes play an important role in the stabilization of water–oil emulsion and their structure formation. Addition of AF 9-10 neonol to the water–oil emulsion leads to a significant decrease in its viscosity, which is particularly strong in the case of the oil emulsions with high asphaltene and resin contents. It was determined that, with the addition of 3% neonol to the water–oil emulsion, a decrease in viscosity is maximum.

Composition of the Products of Thermolysis of Heavy Oil with the Addition of Light Hydrocracked Naphtha

Abstract A series of experiments has been carried out on the thermolysis of heavy oil using 2.5–10.0% light hydrocarbon naphtha additive of vacuum gasoil prepared from conventional oil. It has been shown that the employment of the additive increases the conversion of heavy oil, avoids coke formation in the products of thermolysis as compared to the basic process without additive, and does not prevent the decrease in the viscosity of the products during thermolysis. It has been revealed on the example of the heavy oil of Ashal’chinskoe deposit (Russia) that the thermolysis with the addition of light naphtha gives a liquid product with the yield higher than 97% and the viscosity of less than 80 mm2/s.