SU531797A1 - Anthracene release method - Google Patents

Description

one

This invention relates to a process for the processing of coal tar fractions, in particular the α-anthracene fraction.

There is a method for isolating anthracene by rectification of crude anthracene or anthracene oil in the presence of so-called "extraneous phlegm." In addition, several upper sections of the distillation column are irrigated with reflux (benzene, toluene or other coking chemical solvent), causing forced condensation of distillate vapors. Anthracene is selected as a lateral selection mixed with a solvent (phlegm), thereby eliminating clogging of communications and a reflux condenser with anthracene crystals.

In the known method, phlegm circulating between the upper sections of the column and the refluxing device serves only to create irrigation in the column and does not affect the rectification process. At the same time, several upper plates are inoperative, since there is no mass transfer on them. Therefore, the use of phlegm reduces the effectiveness of the column.

In order to eliminate this drawback according to the invention, the proposed solvent is introduced in a mixture with the feedstock at a 1: 0.5-1 ratio of the initial anthracene fraction and solvent.

Anthracene and carbazole have boiling points of 342 and 352 ° C, respectively. As a solvent, you can use a mixture consisting of di- and trimethylbenzenes and boiling up to 180 ° C (the boiling point of the solvent is significantly lower than the boiling point of the components to be separated). Other benzene hydrocarbons can be used.

The solvent is fed to the distillation column mixed with the raw material and due to the large difference in boiling points is in the column in the vapor phase, which reduces the partial pressure of anthracene and carbazole,

therefore, the solvent plays the role of an inert gas or vacuum and reduces the temperature of the rectification.

When feeding the solvent to the column in the ratio of raw materials from 0.5: 1 to 1: 1, the distillation temperature is reduced by 30-60 ° C. This significantly reduces the cost of tenl and facilitates the process.

Claims (1)

The process is carried out as follows: the feedstock is mixed with the solvent, the resulting suspension is fed to a tube furnace, from where the vapor-liquid mixture enters the distillation column. Carbazole fraction is taken from the bottom plate of the column, and anthracene and phenanthrene vapors mixed with solvent vapors from the top of the column. From the condenser, the solution enters the reflux divider, from where part of it is fed to the irrigation of the column, and the rest to the crystallizer, where anthracene is released, then the mother liquor is separated and sent to the solvent for regeneration. The anthracene crystals are dried and in the form of a 95% product are sent to the warehouse. The method described is explained by the following examples. Example 1. 1000 g of crude anthracene containing 32% pure anthracene is subjected to extractive washing with a solvent. 604 g of a binary mixture, containing 50% anthracene and 36% carbazole, are obtained. By fractionating this mixture with a solvent in the ratio of 1: 0.75, 773 g of a fraction containing 35% anthracene, 58.6% solvent and other impurities was obtained. After crystallization of the fraction from solvents, fugging and drying the crystals, 246 g of 95% anthracene was obtained. The yield of 100% anthracene from resources is 73%. Example 2. 1000 g of crude anthracene is mixed with 500 g of solvent. The mixture is fractionated, resulting in 1040 g of anthracene-phenanthrene fraction containing 23.4% anthracene, 48.1% solvent, phenanthrene and other impurities. Upon crystallization of this fraction, 260 g of precipitate containing 90% is released. anthracene. As a result of non-recrystallization of the precipitate, 216 g of 95% anthracene is obtained. Output 100% -1yugo anthracene from resources 64%. EXAMPLE 3. When rectification of a mixture of anthracene and carbazole, obtained by extractive washing of crude anthracene, without solvent, a fraction containing 88% anthracene is taken at a temperature of 342-344 ° C. To obtain such a fraction, a column with an efficiency of 26 theoretical plates is required. Example 4. When rectification in the presence of a solvent and a ratio of anthracene-carbazole mixture and solvent 1: 0.75, a fraction is taken with the same concentration of anthracene and the same yield at a temperature of 297 ° C. (the distillate consists of this fraction and solvent). To obtain it, a distillation column with the efficiency of 20 theoretical plates is required. Claims The method of extracting anthracene from anthracene-containing fractions by distillation using a solvent and selecting a distillate containing pairs of the desired product and a solvent, is characterized in that, in order to increase the efficiency of the process and reduce the temperature of distillation, the solvent is injected with the feedstock at. the ratio of the initial anthracene fraction and solvent 1: 0.5-1.