INVESTIGATION OF THE TAR DISTILLATE FROM THERMAL DECOMPOSITION OF PEAT–ORE MATERIALS

G. I. KRAVTSOVA, K. K. STRAMKOVSKAYA, S. I. SMOLYANINOV, L. I. AKREITS,
S. V. PETROVA

(Presented by the Scientific-Methodological Seminar of the KhTF)

The main objective of the present work was to study the distillates of tar from the thermal decomposition of peat–ore materials (experimental tar) and the tar from peat semicoking, the preparation conditions and characteristics of which are presented in another article of the present collection [1].

The distillation of the tars was carried out in a nitrogen stream from a 500 ml still equipped with a single-bulb dephlegmator. The characteristics of the obtained distillates with b.p. up to 300°C are given in Table 1.

The data in Table 1 show that, in fractional composition and other physicochemical indices, the distillate of the experimental tar is heavier than the distillate of the semicoking tar. It is characterized by a significant content of total phenols (25.8%) and neutral oils (70.8%).

Investigation of Neutral Oils

To extract the neutral oils, the distillates were first dissolved in sulfuric ether at a ratio of 1:3; then pyridine bases, carboxylic acids, and phenols were extracted from them in the usual way. For a more complete investigation, the neutral oils were distilled into narrow fractions at a residual pressure of 20 mm Hg on a rectification column with an efficiency of 25 theoretical plates. The individual composition of the light fractions (cuts up to 135°C) was studied by gas–liquid chromatography. Taking into account the circumstance that the neutral oils from the thermal decomposition of peat have a very complex

Table 1

Characteristics of distillates boiling up to 300°C

composition and consist of components belonging to different types of chemical compounds; for their analysis two different methods were used. The first method is based on the use, as the liquid phase, of Apiezon $a$ deposited on INZ-600 grade Inza brick in an amount of 15%. The analysis was carried out on an KhL-4 chromatograph using a packed column 7.2 m/6 mm at a thermostat temperature of 220°C and a carrier-gas (helium) flow rate of 100 ml/min.

According to the second method, vacuum oil VM-4 was used as the liquid phase (a 15% solution in benzene, preliminarily thermostated at 270°C for 6 hours) and a copper capillary column 100 m long and 0.5 mm in diameter. Good results were obtained on a “Khrom-2” chromatograph, at a column temperature of 95°C and a carrier-gas (nitrogen) pressure at the column inlet of 0.6 kg/cm².

Qualitative interpretation of the chromatograms was carried out by comparing the relative retention times of the components of the mixture under study with those of individual substances, and also with literature data [2].

Quantitative calculations were carried out by the internal-normalization method, taking correction factors into account [3]. The results of these investigations are given in summary Table 2.

The data in Table 2 show that the fraction of neutral oils, initial boiling point–135°C, is distinguished by a very complex composition (42 components) and is represented mainly by aromatic compounds of the benzene series; the predominant component in it is toluene (11.40% for semi-coking peat tar; 22.2% for the experimental tar). However, the benzene content in the neutral oils of the experimental tar is lower than in the semi-coking tar. Fractions boiling above 135°C could not be identified because of their still more complex composition.

Table 2

Content of individual substances in the neutral oils of the investigated tars, wt.%

2. Investigation of phenols

The distillation of the total phenols into narrower fractions (ten-degree fractions) was carried out at a residual pressure of 20 mm Hg on a column with an efficiency of 25 theoretical plates.

Identification and quantitative determination of the low-boiling phenols (fractions up to 230°C) were performed by gas-liquid chromatography. Chromatography was carried out on a “Khrom-2” chromatograph with a capillary column 50 m/0.5 mm at a thermostat temperature of 152°C.

Tricresyl phosphate and phosphoric acid were used as the phase (10% tricresyl phosphate and 5% phosphoric acid in methanol). The data from these studies are presented in Table 3.

Table 3

Content of individual substances in phenols, wt.%

They indicate that the fraction under investigation consists mainly of phenol, cresols, and xylenols. However, as can be seen from Table 3, the content of these components in the phenols of the experimental tar is somewhat lower than for the peat semicoking tar, but is significantly higher in comparison with the coke-oven tar of Donetsk hard coals [4].

Conclusions

1. A study was carried out of the distillates of the experimental tar and the peat semicoking tar.

2. It was shown that the distillate of the experimental tar is heavier than the distillate of the semicoking tar.

3. The light fractions of phenols and neutral oils were investigated by gas–liquid chromatography.

4. It was established that the concentration of valuable aromatic hydrocarbons in the distillate of the experimental tar is somewhat lower than in the peat semicoking tar.

1. It has been established that the content of xylenols in the experimental tar is 2 times higher, that of toluene 5 times higher, that of phenol 10–15 times higher, and that of cresols more than three times higher than in the tar from the coking of hard coals.

REFERENCES

1. G. I. Kravtsova, K. K. Stramkovskaya, S. I. Smolyaninov, L. Terekhova, V. Bashorina. Investigation of the tar from the thermal decomposition of peat-ore materials.—In the present collection.

2. M. I. Ivanova. The use of gas-liquid chromatography for determining the individual composition of straight-run gasolines boiling up to 150°C. Author’s abstract of a dissertation for the degree of Candidate of Technical Sciences. Irkutsk, 1967.

3. K. A. Golbert, M. S. Vigdergauz. Course in Gas Chromatography. “Khimiya” Publishing House, 1967.

4. M. M. Dmitriev, Ya. M. Obukhovsky. Concise Handbook of the Coke Chemist. “Moskva”, 1960.