deposited on the reactor walls. In the “ethylene” mode, the yield of propylene is insignificant and amounts to 8.3 wt. %.

The investigations carried out showed that straight-run gasoline from gas condensate of the North-Silginskoye field in Tomsk Oblast can be used as feedstock for the process of homogeneous pyrolysis for the purpose of obtaining monoolefins.

Literature

1. “Investigation of gas condensates from fields of Tomsk Oblast as feedstock for microbiological synthesis.” Polytechnic Institute, report on topic III/69, Tomsk, 1971.
2. V. V. Nalimov, N. A. Chernova. Statistical Methods for Planning Extremal Experiments. Moscow, “Nauka,” 1965.
3. L. Z. Rumshinskii. Mathematical Processing of Experimental Results. Moscow, “Nauka,” 1971.

HETEROGENEOUS PYROLYSIS OF STRAIGHT-RUN GASOLINE

S. I. Smolyaninov, M. D. Medvedev, A. V. Kravtsov, L. P. Yarosh

The increasing demand for gaseous unsaturated hydrocarbons requires studies of processes for obtaining olefins that make it possible to increase the capacity of units, reduce production costs and, consequently, obtain cheaper target products.

In the present work, the process of heterogeneous pyrolysis of straight-run gasoline from Samotlor crude oil was investigated. A specially prepared standard iron oxide of the “chda” grade was used as the catalyst, with an Fe content of 69.8–70.1. The gasoline was obtained by atmospheric distillation on an ARN-2 apparatus and has the following physicochemical characteristics:

Boiling range — initial boiling point–180°C.
Yield — 23.8%.
Molecular weight — 114.
Density — 0.7419 g/ml.
Refractive index — 1.420.

Group composition:

Paraffinic hydrocarbons — 64.5 wt. %.
Naphthenic hydrocarbons — 25.7 wt. %.
Aromatics — 9.8 wt. %.

Sulfur-organic compounds are practically absent. The studies were carried out in a unit with a flow-type reactor and a fixed catalyst bed; analysis of the pyrolysis products was performed by the chromatographic method. For the heterogeneous pyrolysis process, the dependence of the qualitative and quantitative composition of the pyrolysis gas on temperature was established at a feed rate of the raw material of 0.1 ml/min per 1 g of \(Fe_2O_3\) and with different experiment durations. Table I gives the composition of the pyrolysis gas during gasoline pyrolysis over iron oxides (experiment duration 20 min):

Table I

Composition of the pyrolysis gas in the heterogeneous pyrolysis
of gasoline from Samotlor crude oil

At a temperature of 750°C and a gasoline fraction feed rate of 0.1 ml/min (Table I), the ethylene content in the pyrolysis gas is 27.3 wt.%, and the total yield of monoolefins reaches 53 wt.% at a pyrolysis-gas yield of 82% by weight of the initial gasoline. Raising the temperature from 650 to 750°C has an insignificant effect on the qualitative and quantitative composition of the gas; the ethylene yield increases by only 2.8 wt.%, and then, with a further increase in the temperature in the reactor, the ethylene yield drops sharply to 14.4 wt.%. A similar dependence is also observed for propylene, whose maximum yield proved to be in the region of the uninvestigated temperatures. With an increase in temperature (above 750°C), the yield values of carbon oxides increase sharply, reaching at 850°C values of 29.4% for CO and 6.1% for \(CO_2\). From the data in Table I it is evident that, with an increase in temperature from 650 to 850°C, the depth of glu-

of hydrocarbon decomposition; in the pyrolysis gas an increase is observed in the content of methane, hydrogen, carbon oxides, and a decrease in the target products. In the course of the study it was found that the optimum temperature is \(750^\circ\mathrm{C}\).

Table 2 shows the dependence of the yield of target products at a temperature of \(750^\circ\mathrm{C}\) on different durations of the experiments, with a feed rate of the raw material of 0.1 ml/min per 1 g of \(\mathrm{Fe_2O_3}\).

Table 2.

Averaged composition of pyrolysis gas at different durations of the pyrolysis process

The study of the gas composition as a function of the duration of the experiment showed that the optimum time is 10 minutes. When the pyrolysis process is carried out under the indicated parameters, the total yield of monoolefins in the pyrolysis gas reaches 57.1 wt.%, which is 4.1 wt.% higher than with a process duration of 20 minutes.