INDIVIDUAL HYDROCARBON COMPOSITION OF FRACTIONS OF MYLDZHINSKOYE GAS CONDENSATE

L. A. Ponomareva, K. K. Stramkovskaya, N. M. Smolyaninova

(Presented by the Scientific-Methodological Seminar of the Chemical-Technological Faculty)

The rapid development of the petrochemical industry requires ever more thorough and detailed knowledge of the hydrocarbon composition of crude oils and petroleum products.

A number of studies carried out to determine the individual hydrocarbon composition of gasoline boiling up to 122°C by gas–liquid chromatography using simple packed columns do not give a complete picture of the composition of the above-mentioned fraction (1, 2).

A more effective separation of the components of this fraction was achieved when capillary columns were used (3).

We investigated the individual hydrocarbon composition of the gasoline from Myldzhinskoye condensate boiling up to 122°C, preliminarily distilled into fractions: initial boiling point—60°, 60–95°, and 95–122°C.

The analysis was carried out on a “Khrom-2” chromatograph using a capillary column 100 m long and with an internal diameter of 0.5 mm. The stationary phase was VM-4 vacuum oil, and the carrier gas was nitrogen.

Each fraction was analyzed at several column temperatures, since a change in temperature changes the elution order of individual hydrocarbons.

The optimum temperature for separating the initial boiling point—60° and 60–95° fractions is 35°C. The 3,3-dimethylpentane with benzene and 2-methylpentane with cyclopentane that were not separated at this temperature were separated, respectively, at 25° and 81°.

For analysis of the 95–122°C fraction, temperatures of 35°, 50°, and 81°C were used.

Qualitative identification of the chromatograms was carried out by retention indices determined for these temperatures (3).

The quantitative calculation was performed by internal normalization according to the “\(h\tau\)” method (\(h\) is peak height, \(\tau\) is the distance from sample introduction), using correction coefficients.

The results of the analysis are given in Table 1.

As can be seen from the data presented, the use of a capillary column and a chromatograph with a flame-ionization detector made it possible to interpret in detail the individual composition of gas-condensate fractions boiling up to 122°C.

In all, the stabilized condensate contains 52 individual hydrocarbons, of which 8.22%, calculated for the initial boiling point—

Table 1

Individual hydrocarbon composition of the stabilized fraction
b.p. 122°C of the Myldzhinskoye gas condensate

Continuation of Table 1

122°C, or 4.17%, calculated on the condensate, is propane—butanes; 19.6, or 19.93, is pentanes. In the composition of the remaining part, the predominant components are 2-methylpentane, n-hexane, methylcyclopentane, 3-methylpentane, cyclohexane, 3-methylhexane, n-heptane, methylcyclohexane, 2-methylheptane, and n-octane.

In total, in the gas condensate up to 122°C there are contained (calculated on the fraction distilled up to 122°C) 34% normal alkanes, 39% isoalkanes, 26.4% cyclanes, of which 12.8% are five- and 13.6% six-membered representatives, and only 0.9% aromatic hydrocarbons.

On the basis of the data obtained, one may conclude that the light fractions of the condensate from the Myldzhinskoye field can serve as feedstock for obtaining aromatic hydrocarbons in the process of catalytic reforming.

Conclusions

1. The optimum separation conditions were selected and the individual hydrocarbon composition of the IBP–122°C fraction of the Myldzhinskoye gas condensate was determined.

2. In the IBP–122°C fraction, 50 individual hydrocarbons were identified; of these, calculated for the fraction, 34% are normal alkanes, 39% isoparaffinic hydrocarbons, 26.4% cyclanes, and 0.9% aromatics.

Literature

1. E. S. Levchenko, E. A. Ponomareva et al. Chemistry and Technology of Fuels and Oils, No. 7, 1965.

2. N. I. Ludova, A. I. Tarasov et al. Collection “Gas Chromatography,” issue IV, VNIITEKhIM, 1966.

3. R. I. Sidorov, M. P. Ivanova. Analytical Chemistry, 21, No. 4, 479, 1966.