SU1766896A1 - Method for purification of naphthalene-containing raw from thionaphthnene - Google Patents

Abstract

SUMMARY OF THE INVENTION: naphthalene sulphonic acid, taken in an amount of 10-20 wt.%, Is heated at 130-170 ° C. the naphthalene sulphonic acid is then separated by washing with water and the purified product is isolated by distillation. Naphthalene losses are 0.08-0.06%. The degree of removal of thionaphthene reaches 97.2%. 4 tab.

Description

This invention relates to methods for cleaning naphthalene and can be used in the coking industry.

Chemical methods are known to purify naphthalene from a sulfur-containing impurity, thionaphthene, by treatment with sulfuric acid in its pure form, in the presence of additives.

A known method of purification of naphthalene by treating it with paraformaldehyde in an acidic medium, followed by neutralization and distillation 2,

The disadvantage of this method also consists in the formation of by-products and environmentally hazardous waste.

The closest to the invention is the method of cleaning naphthalene by its

heating with anhydrous sulfonic acid with the addition of paraformaldehyde followed by distillation 3.

The disadvantage of this method lies in the presence of additional losses of naphthalene due to its condensation with para-formaldehyde, as well as in the formation of acid waste. In addition, the need to use paraformaldehyde for cleaning naphthalene creates unsatisfactory operating conditions.

The purpose of the invention is to reduce the loss of naphthalene.

The goal is achieved in that the naphthalene sulfonic acid is used in an amount of 10-20% by weight and the separation of naphthalene sulfonic acid is carried out by washing with water. At the same time, naphthalene sulfonic acid becomes a reagent for the removal of thionaphthene in the form of non-volatile resinous compounds soluble in naphthalene, separated in

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process of rectification of the product being purified.

This allows you to significantly reduce the loss of naphthalene, as well as to implement a virtually waste-free technology for cleaning naphthalene-containing raw materials.

 The essence of the method is as follows.

With melting, the naphthalene-containing naphthalene is added with stirring 10-20 wt.% Naphthalenesulfonic acid. The mixture is heated to 130-170 ° C and maintained in this mode for 5-19 hours, depending on the desired degree of purification of the initial naphthalene. Next, the reaction mass is cooled to 95 ° C and 4-5 wt.% Of water are added. After stirring for 15–20 min, it is subjected to one-hour sieving, followed by separation into purified naphthalene and a solution of naphthalene sulfonic acid. The latter is subjected to dehydration, for example, by distillation and returned to the processing of a new batch of the original naphthalene-containing raw material.

PRI me R. 1000 kg (10 tons) of molten, pressed naphthalene, which contains hydrinden and indene, 7 kg (0.07%), naphthalene 9627 kg (96.27%) of thionaphthene, 311 kg (3, 11%), methylnaphthalenes (a. + / 3) 55 kg (0.55% / -methylnaphthalene and 0.02% a-methylnaphthalene). 1500 kg (15%) of molten naphthalene sulfonic acid, which is a sulfo mass, was obtained by sulfonating naphthalene with 94% sulfuric acid at 160 ° C. While sulfomass contains sulfuric acid 5 wt.% (P-naphthalenesulfonic acid 87%, naphthalene 7%, water and other things up to 100% by weight). With stirring, raise the temperature to 150 ° C and hold for 5 hours. Then the reaction mass is cooled to 95 ° C and 500 kg of water (5%) are added. After 20 minutes of stirring, the reaction mass is subjected to sludge followed by separation of the lower layer - naphthalene sulfonic acid in the amount of 1967 kg and the upper - washed (purified) naphthalene in the amount of 10033 kg.

Washed naphthalene contains naphthalene 9625 kg, thionaphthene 100 kg, hydrindene + indene 2 kg, (a + ft) -methylnaphthalene 50 kg, naphthalene sulfonic acid 15 kg, resinous nonvolatile substances 239 kg, loss 2 kg. The degree of removal of thionaphthene is 68%, the loss of naphthalene is 0.02%. Washed naphthalene containing 75 kg of free sulfuric acid is subjected to

neutralization with alkali solution and then distillation to obtain the finished product. An aqueous solution of naphthalenesulfonic acid is subjected to dehydration, after

which is used for the next cleaning operation.

Below are the results of experiments on the purification of molded naphthalene containing 3,11 wt.% Thionaphthene, in

various operating conditions, confirming the validity of the selected technological process parameters (Table 1).

As can be seen from the above data, the optimal consumption of sulfonic acids is 1020 wt.%, Preferably 15 wt.%. Reducing the consumption of sulphonic acid below the specified limit leads to a sharp decrease in the efficiency of thio-naphthene cleaning. The increase in consumption is economically unjustified.

Table 2 shows the experimental results illustrating the effect of temperature on the process of removing thionaphthenes from the original thioneaphthenic naphthalene.

The data show that the optimal process temperature limits are 130-170 ° C, preferably 150 ° C. Temperature reduction

below 130 ° C leads to an increase in the concentration of thionaphthene, i.e. to the deterioration of the degree of purification naphthalene-containing raw materials. Increasing the process temperature is not economically feasible, since the degree

the extraction of organo-sulfur remains virtually at the same level.

Table 3 presents data illustrating the effects of processing time on

the process of removing thionaphthene from the original naphthalene.

As can be seen from the above data, the optimum process time is 4-8 hours, preferably 5.0. A reduction in processing time impairs the cleaning efficiency, as the degree of removal of thionaphthene decreases. The increase in time leads to a significant improvement in the degree of purification - above 97%. but

this degree of purity is not required for 1st grade naphthalene. 68% is sufficient, which corresponds to the presence of naphthalene in up to 1.0% thionaphthene.

At the same time, these data indicate that it is possible to achieve the highest degree of purification without significant losses in naphthalene.

Table 4 shows the comparative data of the proposed method and the prototype.

Claims (1)

Invention Formula The method of purification of naphthalene-containing raw material otthionaphthen by treatment with naphthalene sulfonic acid at 130-170 ° C, separation of naphthalene sulfonic acid and separation a distilled purified product, characterized in that, in order to reduce the loss of naphthalene, naphthalene sulfonic acid is used in an amount of 10-20 May. % and separation of naphthalenesulfonic acid is carried out by washing with water. Table 1 table 2 Table 3 Indicator The content of thionaphthene in the feedstock in terms of sulfur,% The residual content of thionaphthene in the purified product in terms of sulfur. % The degree of removal of thionaphthene,% The output of naphthalene,% Loss of naphthalene. % Table 4 Prototype The proposed method 0.4-0.64 0.74 Up to 0.02 Up to 97 99.9 0.02-0.06