Spectral Method for Determining Vanadium in Oil Samples from Fields in Tomsk Oblast
Abstract Generated abstract
This paper presents a spectral method for quantifying vanadium in crude oil samples from several fields in Tomsk Oblast, addressing the laborious nature of the standard ashing and photometric procedure. The authors describe sample ashing, dissolution in sulfuric acid, addition of cobalt and sodium carbonate to enhance spectral line intensity, and spectrographic measurement using prepared vanadium standards. Results for seven crude oil samples show close agreement between the proposed spectral method and the standard photometric method over vanadium concentrations from about 10^-4 to 10^-2 percent. The study concludes that a 10 g sample is suitable for this concentration range and that the spectral procedure can serve as a less labor-intensive alternative for routine determination.
Full Text
SPECTRAL METHOD FOR DETERMINING VANADIUM IN OIL SAMPLES FROM FIELDS IN THE TOMSK REGION
I. S. KARPENKO, B. N. BESPROZVANNYKH, E. A. KURYSHEVA
(Submitted by Professor P. A. Udodov)
In characterizing the material composition and properties that determine the direction of industrial processing of oil from a given field, an essential element is the determination of its vanadium content. According to the standard method for determining vanadium in petroleum products (GOST 10364—63), the sample is subjected to ashing, followed by treatment with acids and fusion of the acid residue. The conditions for isolating it from oil and separating it from accompanying elements have been little studied, and the existing methods are labor-intensive.
Determination of vanadium from aqueous solutions is possible by various methods: in the form of an oxine complex [1], a phosphorotungstate complex [2], by the peroxide method [3], etc. Rapid methods include spectral and chemiluminescent methods for determining vanadium.
The aim of our work was to clarify the optimal conditions for determining vanadium in oils from various fields of the Tomsk Region. Studies were carried out along a number of lines. The final procedure adopted by us for determining thousandths of a percent of vanadium in oil is briefly as follows.
A 10 g oil sample was placed in a porcelain dish and carefully heated on an electric hot plate covered with asbestos at a temperature of 300—400°C to a thick consistency and the formation of coke. The petroleum coke was ashed in a muffle furnace with a gradual increase in temperature to 500°C. The resulting ash was dissolved in 5—7 ml of 10% sulfuric acid and heated until complete decomposition of the sample; the solution was evaporated to a small volume.
The residue was again dissolved in 1 ml of 10% sulfuric acid, to which 0.015% cobalt (in the form of CoSO₄·7H₂O) and 0.2% sodium carbonate had been added to increase the intensity of the spectral lines. Spectrography was carried out on an ISP-28 spectrograph by the three-standard method. The standards were prepared by dissolving a weighed portion of V₂O₅ in 10% sulfuric acid with the corresponding additions of 0.015% cobalt and 0.2% sodium carbonate, within the range of standard concentrations from \(1 \cdot 10^{-4}\) to \(5 \cdot 10^{-3}\%\).
Onto electrodes prepared in the corresponding manner, the solution under study was introduced in a definite volume, and the standard solution in the same volume. During spectrography, a current of 15 A was used, the slit width was 0.02 mm, and the exposure was 45 sec.
The results of parallel determinations are shown below in the table.
Table
| Sample No. | Oil-field name | Vanadium content, % — spectral method | Vanadium content, % — photometric method |
|---|---|---|---|
| 1 | Sovetskoye | \(1.10^{-3}\) | \(9.10^{-4}\) |
| 2 | Sovetskoye | \(2.3.10^{-3}\) | \(1.96.10^{-3}\) |
| 3 | Sovetskoye | \(1.8.10^{-3}\) | \(1.8.10^{-3}\) |
| 4 | Sobolinoye | \(2.9.10^{-3}\) | \(2.7.10^{-3}\) |
| 5 | Nyurolskoye | \(3.10^{-4}\) | \(3.10^{-4}\) |
| 6 | Nyurolskoye | \(1.10^{-4}\) | \(1.10^{-4}\) |
| 7 | Poludennoye | \(5.10^{-3}\) | not studied |
vanadium in 7 samples of crude oil from four fields in Tomsk Oblast by the spectral method described above and by the standard photometric method. Photometry was carried out on an MF-4 microphotometer.
The data in the table show that the results of parallel determinations of vanadium for each sample coincide or have small fluctuations. The discrepancies in the figures for samples 1, 2, and 3 from the Sovetskoye field and 5 and 6 from the Nyurolskoye field are explained by the fact that these samples were taken from different wells.
Conclusions
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A variant of the spectral method has been developed for determining the quantitative content of vanadium in crude oil.
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The proposed method of spectral analysis is less labor-intensive than the standard photometric method.
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For vanadium concentrations in oil from \(10^{-2}\) to \(10^{-4}\%\), the proposed method of analysis gives results close to those of the standard method, which indicates their interchangeability.
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The sample weight of 10 g recommended by us is optimal for crude-oil samples within the indicated concentration ranges and was established experimentally.
Literature
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I. P. Alimarin. Journal of Analytical Chemistry, 10, 1, 569, 1955.
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A. V. Vinogradov. Proceedings of the USSR Academy of Sciences, Series A, 10, 249, 1931.
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A. K. Babko and A. I. Volkova. Factory Laboratory, 5, 518, 1952.
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GOST 10364-63. Dark petroleum products. Determination of vanadium content by the colorimetric method. Moscow, 1965.
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V. A. Zinchenko and O. D. Baranova. Collected volume Titanium and Its Alloys, Issue 78, 251, 1962.