Investigation of the Group and Structural-Group Composition of Middle and Heavy Fractions of Oils from the Nizhnevartovsk Region of Western Siberia
Abstract Generated abstract
This study examines the group and structural group composition of middle and heavy petroleum fractions from the Sovetskoe and Samotlor fields in the Nizhnevartovsk region of Western Siberia. Fifty degree kerosene, gas oil, and oil cuts were separated by adsorption chromatography on silica gel into methane naphthenic and aromatic groups, characterized by refractive index, molecular weight, elemental composition, structural group calculations, and ultraviolet spectroscopy. The results show that with increasing boiling range the total aromatic content and number of rings in aromatic hydrocarbons generally increase, while the share of cyclic structures in the average molecule decreases. The aromatic fractions are interpreted as progressing from mainly alkylbenzenes and naphthalene derivatives to higher substituted naphthalenes and, in the heaviest cuts, phenanthrene derivatives.
Full Text
STUDY OF THE GROUP AND STRUCTURAL-GROUP COMPOSITION OF MIDDLE AND HEAVY FRACTIONS OF OILS FROM THE NIZHNEVARTOVSK REGION OF WESTERN SIBERIA
N. S. Kislitskaya, A. I. Levashova
(Presented by the scientific-methodological seminar of the organic departments of the Faculty of Chemical Technology)
The study of the chemical composition of kerosene–gas-oil and oil fractions of petroleum—the main part of diesel and jet fuels and lubricating oils—is one of the most important tasks of petroleum chemistry.
The present study is devoted to determining the structural types of hydrocarbons comprising the middle \((200—350^\circ\mathrm{C})\) and heavy \((350—K. K.^\circ\mathrm{C})\) fractions of oils from two of the largest fields in Western Siberia—the Sovetskoe and Samotlor fields, whose physicochemical properties were studied by us earlier [1, 2].
The indicated fractions (50-degree fractions) were obtained by atmospheric-vacuum rectification on an ARN-2 apparatus. For their separation, adsorption chromatography on ASK silica gel was used, with collection of the following groups of hydrocarbons [3]:
1) methane-naphthenic — \((n_D^{20}\) not \(> 1.49)\);
2) 1st group aromatic — \((n_D^{20} — 1.49 \div 1.53)\);
3) 2nd group aromatic — \((n_D^{20} — 1.53 \div 1.55)\);
4) 3rd group aromatic — \((n_D^{20} — 1.55 \div 1.59)\);
5) 4th group aromatic — \((n_D^{20} —\) more than \(1.59)\).
The groups obtained were characterized by refractive index, molecular weight, and elemental composition.
The structural-group composition of the 50-degree fractions was calculated by the method \(n = d = M\), and that of individual hydrocarbon groups by the method \(M = n_D^{20}\) [3, 4]. To confirm and supplement the data on structural-group composition, UV spectroscopy was used for the aromatic hydrocarbons of all groups. Spectra were recorded on an SF-4 spectrophotometer in the range 200–360 nm. Interpretation of the spectra was carried out according to literature data [5, 6].
Table 1 gives certain physicochemical properties and the group hydrocarbon composition of the kerosene–gas-oil and oil fractions of the Sovetskoe and Samotlor oils. Their structural-group composition is shown in Table 2.
Tables 3 and 4 present the principal results of determining the structural-group composition of the components of the indicated fractions. From these data it is evident that, with increasing temperature limits of collection, the number of rings entering into the composition of aromatic hydrocarbons increases regularly for all groups, while the percentage content of cyclic
Table 1
Group hydrocarbon composition of kerosene–gas-oil and oil fractions of oils from the Sovetskoe and Samotlor fields of Western Siberia
| Fraction boiling range, °C | Yield on oil, wt. % | $\rho_4^{20}$ | Molecular weight | $n_D^{20}$ | Methane–naphthene, % | 1st group | 2nd group | 3rd group | 4th group | Total aromatics, % | Sulfurous fractions and resins, % |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Sovetskoe field | |||||||||||
| 200–250 | 9.6 | 0.8250 | 177 | 1.4615 | 74 | 13 | 4 | 9 | — | 26 | — |
| 250–300 | 10.6 | 0.8470 | 242 | 1.4760 | 70 | 16 | 4 | 9 | — | 29 | 1 |
| 300–350 | 8.8 | 0.8700 | 248 | 1.4900 | 67 | 16 | 5 | 11 | — | 32 | 1 |
| 350–400 | 9.1 | 0.8920 | 284 | 1.5030 | 56 | 21 | 5 | 11 | 6 | 43 | 1 |
| 400–450 | 9.1 | 0.9165 | 353 | 1.5181 | 52 | 21 | 9 | 12 | 4 | 46 | 2 |
| Samotlor field | |||||||||||
| 200–300 | 18.4 | 0.8416 | 194 | 1.4680 | 73 | 13 | 4 | 8 | 2 | 27 | — |
| 300–350 | 10.0 | 0.8750 | 256 | 1.4896 | 60 | 18 | 5 | 12 | — | 35 | 5 |
| 350–400 | 9.6 | 0.9020 | 310 | 1.5027 | 52 | 22 | 4 | 18 | 3 | 47 | 1 |
| 400–450 | 7.0 | 0.9250 | 353 | 1.5160 | 50 | 21 | 8 | 17 | 3 | 49 | 1 |
structures in the average molecule decreases. In the series of mono-, bi-, and polycyclic aromatic hydrocarbons isolated from fractions with identical boiling ranges, the content of carbon atoms in paraffinic structures decreases.
Table 2
Structural-group composition of kerosene-gas oil and oil fractions of Soviet and Samotlor oils (the n-d-M method)
| Fraction sampling temperature, °C | $C_A$ | $C_H$ | $C_K$ | $C_P$ | $K_A$ | $K_H$ | $K_O$ |
|---|---|---|---|---|---|---|---|
| Soviet oil | |||||||
| 200–250 | 15 | 29 | 44 | 56 | 0.33 | 0.72 | 1.05 |
| 250–300 | 20 | 23 | 43 | 57 | 0.50 | 0.75 | 1.25 |
| 300–350 | 23 | 18 | 41 | 59 | 0.71 | 0.58 | 1.29 |
| 350–400 | 25 | 15 | 40 | 60 | 0.78 | 0.85 | 1.63 |
| 400–450 | 29 | 10 | 39 | 61 | 1.28 | 0.58 | 1.86 |
| Samotlor oil | |||||||
| 200–250 | 13 | 33 | 46 | 54 | 0.28 | 0.77 | 1.05 |
| 250–300 | 17 | 31 | 48 | 52 | 0.43 | 0.76 | 1.19 |
| 300–350 | 19 | 25 | 44 | 56 | 0.59 | 0.83 | 1.42 |
| 350–400 | 20 | 24 | 44 | 56 | 0.76 | 1.16 | 1.92 |
| 400–450 | 23 | 22 | 45 | 55 | 1.00 | 1.36 | 2.36 |
Monocyclic aromatic hydrocarbons of both oils consist mainly of alkylbenzenes. With increasing temperature of fraction sampling, an increase is observed in the number of carbon atoms belonging to aromatic structures: for example, from 6.53 in the 200–250°C cut to 8.10 in the 400–450°C fraction of Soviet oil, and from 6.8 to 9.00 in the corresponding cuts of Samotlor oil.
The UV-spectroscopy data indicate an increase, with rising boiling temperature of the fractions, in the number of substituents in the benzene ring of the aromatic hydrocarbons of the 1st group. This is evidenced by the shift of the absorption maximum in the region of 260–270 nm toward longer wavelengths.
With increasing temperature limits of fraction sampling, the absorption bands at the indicated wavelengths become increasingly diffuse, which, together with data on their structural-group composition (Tables 3, 4), indicates a decrease in the proportion of aromatic rings in the mixed molecule.
The similarity of the UV spectra of the 1st group of aromatic hydrocarbons for both oils is noteworthy.
According to the data of Tables 3 and 4, as well as the results of spectral analysis, the 2nd group of aromatic hydrocarbons is represented mainly by naphthalene derivatives. With increasing temperature of fraction sampling, the number of substituents in the naphthalene structures increases (shift of the absorption maximum in the region of 220 nm toward longer wavelengths [6]).
The third group of aromatic hydrocarbons of the kerosene-gas oil fractions also consists of naphthalene structures; in higher-boiling
Table 3
Structural-group composition of components of kerosene–gas-oil and oil fractions of Sovetskoe crude oil (method \(M\!-\!n_D^{20}\!-\!C\))
| Fraction cut temperature, °C | Components | \(M_n\) | \(n_D^{20}\) | C, % | H, % | Empirical formula | \(K_A\) | \(K_H\) | \(K_A\), % | \(K_H\), % | \(C_A\) | \(C_H\) | \(C_A\), % | \(C_H\), % |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
| 200–250 | Methano-naphthenes | 179 | 1.4417 | 90.0 | — | — | 0 | 0.66 | 0 | 35.5 | 0 | 6.80 | 0 | 37.5 |
| 200–250 | I group aromatics | 156 | 1.5007 | 90.0 | 10.0 | \(C_{13}H_{17.5}\) | 1.10 | — | 56.0 | — | 6.53 | 5.65 | 56.0 | — |
| 200–250 | II group aromatics | 183 | 1.5360 | 89.0 | 11.0 | \(C_{13.7}H_{18.3}\) | 1.51 | — | 62.5 | — | 8.77 | 4.00 | 63.3 | — |
| 200–250 | III group aromatics | 218 | 1.5674 | 87.2 | 10.4 | \(C_{16.5}H_{22.4}\) | 2.17 | — | 70.4 | — | 11.20 | 2.87 | 68.6 | — |
| 250–300 | Methano-naphthenes | 195 | 1.4475 | — | — | — | 0 | 0.82 | 0 | 36.2 | 0 | 8.00 | 0 | 36.4 |
| 250–300 | I group aromatics | 206 | 1.5009 | 87.8 | 11.9 | \(C_{15.5}H_{25.8}\) | 1.20 | — | 45.5 | — | 7.05 | 9.10 | 46.0 | — |
| 250–300 | II group aromatics | 228 | 1.5420 | 89.3 | 9.9 | \(C_{17.3}H_{22.4}\) | 1.80 | — | 48.5 | — | 10.30 | 7.10 | 47.3 | — |
| 250–300 | III group aromatics | 275 | 1.5724 | 89.8 | 9.3 | \(C_{21.6}H_{25.5}\) | 2.44 | — | 60.0 | — | 12.90 | 6.90 | 64.0 | — |
| 300–350 | Methano-naphthenes | 238 | 1.4575 | — | — | — | 0 | 1.30 | 0 | 37.5 | 0 | 11.00 | 0 | 37.7 |
| 300–350 | I group aromatics | 217 | 1.5054 | 87.8 | 11.6 | \(C_{17.0}H_{29.5}\) | 1.27 | — | 43.2 | — | 7.40 | 9.98 | 45.7 | — |
| 300–350 | II group aromatics | 283 | 1.5747 | 89.9 | 8.7 | \(C_{21.4}H_{24.8}\) | 2.50 | — | 61.5 | — | 12.90 | 7.50 | 60.0 | — |
| 300–350 | III group aromatics | 242 | 1.5421 | 88.4 | 10.1 | \(C_{19.0}H_{24.6}\) | 1.86 | — | 56.0 | — | 10.50 | 8.10 | 55.0 | — |
Continuation of Table 3
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 350—400 | Methano-naphthenic | 254 | 1,4599 | 87,2 | — | — | 0 | 0,80 | 0 | 19,6 | 0 | 17,10 | 0 | 20,2 |
| 350—400 | Group I arom. | 287 | 1,5019 | 87,2 | 12,1 | C₂₂,₃H₃₃,₅ | 1,35 | — | 34,5 | — | 7,20 | 15,00 | 36,3 | — |
| 350—400 | Group II arom. | 292 | 1,5385 | 87,9 | 10,7 | C₂₃,₄H₃₂,₁ | 1,98 | — | 47,0 | — | 10,70 | 12,51 | 49,1 | — |
| 350—400 | Group III arom. | 304 | 1,5700 | 86,7 | 9,5 | C₂₄,₁H₃₃,₀ | 2,56 | — | 46,4 | — | 13,25 | 7,60 | 5,70 | — |
| 350—400 | Group IV arom. | 308 | 1,5021 | 87,7 | 8,7 | C₂₅,₃H₂₉,₉ | 3,82 | — | 72,0 | — | 16,70 | 8,60 | 72,0 | — |
| 400—450 | Methano-naphthenic | 357 | 1,4793 | — | — | — | 0 | — | 0 | — | 0 | — | 0 | — |
| 400—450 | Group I arom. | 356 | 1,5066 | 87,8 | 11,9 | C₂₆,₆H₄₂,₀ | 1,43 | — | 29,0 | — | 8,10 | 19,00 | 31,0 | — |
| 400—450 | Group II arom. | 366 | 1,5335 | 89,2 | 10,2 | C₂₈,₅H₃₉,₅ | 2,25 | — | 41,4 | — | 12,10 | 17,30 | 45,0 | — |
| 400—450 | Group III arom. | 372 | 1,5763 | 89,7 | 9,9 | C₂₈,₆H₃₇,₀ | 2,94 | — | 71,5 | — | 15,20 | 14,00 | 57,7 | — |
| 400—450 | Group IV arom. | 377 | 1,5933 | 88,7 | 8,8 | C₂₈,₄H₃₇,₀ | 3,38 | — | 57,0 | — | 17,00 | 10,50 | 60,0 | — |
Table 4
Structural-group composition of kerosene–gas-oil and oil fractions of Samotlor oil (Kherya, Fenske method, etc.)
| Fraction boiling temperature, °C | Components | Molecular weight, M | Refractive index, $n_D^{20}$ | $K_A$ | $K_H$ | $K_{\Sigma}$ | $C_A$, % | $C_P$, % | $C_A^{\circ}$, % | $C_H$, % |
|---|---|---|---|---|---|---|---|---|---|---|
| 200–300 | 1st gr., arom. | 186 | 1.5007 | 1.15 | 46.4 | 6.80 | 7.80 | |||
| 200–300 | 2nd gr., arom. | 189 | 1.5365 | 1.59 | 60.0 | 8.92 | 4.81 | |||
| 200–300 | 3rd gr., arom. | 205 | 1.5625 | 1.95 | 68.6 | 10.76 | 2.00 | |||
| 300–350 | Methanonaphthene | 273 | 1.4589 | 0 | 1.0 | 31.2 | 0 | 13.40 | 0 | 13.40 |
| 300–350 | 1st gr., arom. | 238 | 1.5014 | 1.26 | 38.7 | 7.28 | 8.00 | |||
| 300–350 | 2nd gr., arom. | 253 | 1.5375 | 1.86 | 50.3 | 10.10 | 5.50 | |||
| 300–350 | 3rd gr., arom. | 258 | 1.5663 | 2.28 | 54.0 | 12.11 | 2.00 | |||
| 350–400 | Methanonaphthene | 289 | 1.4593 | 0 | 0.9 | 36.3 | 0 | 14.00 | 0 | 14.00 |
| 350–400 | 1st gr., arom. | 308 | 1.5016 | 1.38 | 32.6 | 7.88 | 16.40 | |||
| 350–400 | 2nd gr., arom. | 338 | 1.5383 | 2.13 | 43.3 | 11.30 | 14.85 | |||
| 350–400 | 3rd gr., arom. | 291 | 1.5536 | 2.33 | 52.0 | 11.80 | 8.07 | |||
| 350–400 | 4th gr., arom. | 364 | 1.5929 | 3.47 | 60.0 | 17.50 | 9.06 | |||
| 400–450 | Methanonaphthene | 385 | 1.4692 | |||||||
| 400–450 | 1st gr., arom. | 292 | 1.5076 | 1.66 | 30.7 | 9.00 | 15.29 | |||
| 400–450 | 2nd gr., arom. | 298 | 1.5383 | 2.38 | 31.7 | 9.45 | 8.57 | |||
| 400–450 | 3rd gr., arom. | 421 | 1.5620 | 2.89 | 26.7 | 8.50 | 13.78 | |||
| 400–450 | 4th gr., arom. | 439 | 1.5958 | 3.80 | 53.5 | 18.80 | 15.07 |
the corresponding cuts contain 3-ring catacondensed rings, but tri- and polysubstituted naphthalenes predominate. Only in the 400–450°C fractions of both oils was the presence of phenanthrene rings recorded (maximum at 260 nm and thereafter a sharp decline of the absorption curve).
The fourth group of aromatics of both oils is represented mainly by phenanthrene derivatives.
REFERENCES
-
S. I. Smolyaninov, N. M. Smolyaninova, K. K. Stramkovskaya. Questions of Chemistry. Issue 26. Tomsk, TSU Publishing House, 1969, p. 22.
-
N. M. Smolyaninova, S. I. Smolyaninov, L. E. Aleksandrova, V. K. Zhurba, V. B. Orlovskii. Proceedings of TPI, vol. 253, 1976. Tomsk, TPI Publishing House.
-
Manual for the Analysis of Petroleum. Edited by A. I. Bogomolov and L. I. Khotyntseva. Leningrad, “Nedra,” 1966.
-
K. Van Nes, X. Van Westen. Composition of Oil Fractions and Their Analysis. Moscow, Izd. IL, 1954.
-
B. A. Smirnov. In: Methods for the Analysis of Organic Compounds of Petroleum, Their Mixtures, and Derivatives. Moscow, “Nauka,” 1969, p. 133.
-
M. M. Kusakov, N. A. Shimanko, M. V. Shishkina. UV Absorption Spectra of Aromatic Hydrocarbons. Atlas of Spectra. Moscow, Publishing House of the USSR Academy of Sciences, 1963.