SU394349A1 - METHOD FOR PREPARING CLEAN NAFTALINE - Google Patents

Description

The invention relates to a process for the preparation of pure substances, in particular the production of naphthalene of high purity.

A known method of producing pure naphthalene by blowing gas through a naphthalene melt at a pressure above 2 atm and a temperature above 218 ° C, followed by co-oxidation of naphthalene vapor by distilling the resulting liquid condensate.

However, the change in elevated pressure and high temperature for naphthalene treatment has its negative sides, especially since this method does not provide a sufficiently high degree of purity of the product. According to the proposed method, condensation should be carried out by fractional sublimation.

Gas blowing should be carried out at a temperature not higher than iOO ° C, and the first stage of co-detection should be carried out at a temperature.

The essence of the invention is as follows. A gas carrier, saturated with naphthalene vapor, successively passes through a system of capacitors operating in different temperature conditions. Naphthalene crystals discharged in condensers as a result of sublimation condensation are significantly different in quality, which is explained by different dependencies

pressures of nacbiuieinibix of individual vagaries of mixtures from temerature. In particular, the content in the product is the most difficult to remove from the impurity-thionefteia and the naphthalene-p-methy l-naphthalene satellite, which increases with the growth of the condensation temperature.

The process for producing pure naphthalene is carried out as follows; the initial naphthalene is heated to 100 ° C. A carrier gas (air, nitrogen, etc.) is passed through the molten naphthalene, which is also heated to. In the process of bubbling, the carrier gas is saturated with naphthalene vapor and the mixture formed with the vapor-gas mixture is connected to a system of series-connected capacitors. In each condenser, with the help of a thermostatic jacket, a certain temperature is maintained: 60-70 ° C in the first condenser along the gas flow and then the temperature of the stepped temperature drops to 20-10 ° C last (see Tables 1, 2, 3).

In the latter, cold condensate, the product of low quality is condensed with a high content of 11 l of tponaphtem and other impurities.

In tab. Figure 1 shows the data on the distribution of premixes over condensers. Depending on the condition of condensation. Data obtained by the method of acc-spectra:

g a b l.n u a 1

T a b l and c a

Thus, the proposed method ensures the production of naphthalene not only according to standard purity indicators: crystallization temperature, action of sulfuric acid, io, and according to the degree of purification from basic irimeses (thioneften, p-methylnaphthalene, visible).

The purity of the finally purified according to the proposed method of iphthalide 1 g depends also

G a b l and c a 2

,,., Cleaned naphthalene

Quality

5 - h:; r: lathaline

78.8079.00

0,800,50

Complies with the OFvpacKH control solution uY9 6

the quality of the feedstock, as shown in the table. 2 and 3.

Subject invention

The method of obtaining pure naphthalene by blowing iositel gas through naphthalene gas at elevated temperatures with

25 by subsequent condensation of naphthalene vapor, characterized in that, in order to increase the purity of the product and simplify the process, condensation is carried out by fractional sublimation in several stages.

30 2. The method according to claim 1, wherein the purge is carried out at a temperature not higher than 100 ° C and the first stage of condensation is carried out at a temperature of 60-70 ° C.