JPH04265202A - Method for production of hydrochloric acid - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is based on CH3OH+3Cl
This invention relates to a method for producing hydrochloric acid of chlorine and methanol produced by the reaction of 2+H2O=6HCL+CO2. Furthermore, the present invention relates to the use of hydrochloric acid or hydrochloric acid and methanol produced by the method of the present invention for the production of chlorine dioxide.

0002

BACKGROUND OF THE INVENTION The above reaction itself is well known. In particular, the use of the above reaction to reduce the formation of chlorine as a by-product in the production of chlorine dioxide is described in Finnish Patent Application No. 895028, 894901.
No. 881,440. In the methods disclosed in these applications, chlorine, a by-product of the chlorine dioxide production process, reacts with a reducing agent, such as methanol. However, this process is not used for the production of hydrochloric acid.

0003

[Problem to be solved by the invention] Conventionally, hydrochloric acid
It is produced by the reaction of chlorine gas and hydrogen gas in a hydrochloric acid burner with a special structure designed specifically for this reaction. This process uses large amounts of hydrogen,
Since it is practically impossible to transport hydrogen in large quantities, the production of hydrochloric acid is practically only possible in the vicinity of large hydrogen sources, such as chlorine or chlorate plants. Ta. For this reason, transportation of hydrochloric acid requires a great deal of cost. That is, normal hydrochloric acid is commercially available as a 32% aqueous solution and accounts for about 20% of the carrying load.
/3 is water.

[0004] Also, today, for the purpose of environmental protection, it is avoided to produce hydrochloric acid using sulfur compounds. In this case, for example ER
Methods such as the CO R5 method are used in practice. In this R5 method, chlorine dioxide is produced from sodium chlorate and hydrochloric acid. However, this method consumes very large amounts of hydrochloric acid. For example, in a reactor capable of producing 30 tons of chlorine dioxide in 24 hours,
40 tons of 100% strength hydrochloric acid are used. That is, more than 120 tons of 32% aqueous solution will be consumed in 24 hours. Additionally, chlorine is produced as a by-product. Although today's environmental protection demands have reduced the use of chlorine in bleaching, the reactor described above
Along with tons of chlorine dioxide, 20 tons of chlorine are produced as by-products.

SUMMARY OF THE INVENTION The object of the present invention is therefore to provide a method for producing hydrochloric acid that does not use hydrogen gas and does not require the use of special burners resistant to high temperatures.

[0006] Another object of the present invention is to provide a method for producing hydrochloric acid by which a highly concentrated aqueous solution of hydrochloric acid can be obtained.

A further object of the present invention is to provide a method for producing chlorine dioxide without using a large amount of hydrochloric acid.

[0008]

SUMMARY OF THE INVENTION In the present invention, hydrochloric acid is produced by reacting chlorine with an aqueous solution of methanol at elevated temperatures. The inventors have discovered that the yield of this reaction is significantly improved by light. Therefore, in the present invention, light is irradiated and acts on the reaction mixture during the above reaction. Water dilutes the reaction mixture and
It aids in heat transfer and also hydrolyzes intermediate products.

In the method of the present invention, for example, theoretically 4
40 tons of 10 from 0 tons of chlorine and 6 tons of methanol
0% concentration of hydrochloric acid is produced and the chlorine produced as a by-product during the production of chlorine dioxide is used in this process. Therefore, the problems caused by the above-mentioned conventional methods when generating chlorine dioxide can be solved. Further, as mentioned above, since chlorine produced in the chlorine dioxide production process can be used, for example, when producing 40 tons of hydrochloric acid, only 20 tons of chlorine is newly required.

According to the first aspect of the present invention, chlorine and methanol are reacted to form hydrochloric acid, characterized in that light is applied to a reaction solution containing chlorine and methanol in a reaction tower at an elevated temperature. Alternatively, a method for producing a solution of hydrochloric acid and methanol is provided.

According to a second aspect of the present invention, chlorine and methanol are treated by applying light to a reaction solution containing chlorine and methanol in a reaction tower in the presence of water and at an elevated temperature. Provided is a method for using a solution of hydrochloric acid and methanol, which comprises producing chlorine dioxide from sodium chlorate in the presence of a reducing agent using a solution of hydrochloric acid and methanol produced by reacting methanol. be done.

In the second configuration of the present invention, the hydrochloric acid and reducing agent used in the chlorine dioxide production reaction are vapors of a mixture of hydrochloric acid and methanol flowing out from the reaction tower. I can do it. Moreover, the hydrochloric acid and reducing agent used in the chlorine dioxide production reaction can also be a mixture of hydrochloric acid, methanol, and water.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the apparatus used for the reaction according to the invention. Methanol and water are circulated through the apparatus. Chlorine is fed into the gas space of the column. Hereinafter, the above tower will be referred to as a reaction tower, and the circulating aqueous solution will be referred to as a reaction solution.

Under normal air pressure conditions, the hydrochloric acid concentration in the reaction solution increases to 30-35%. Thereafter, the generated hydrochloric acid remains in the reaction tower. For the purpose of recovering the generated hydrochloric acid, an absorption tower for circulating an absorption solution is attached to the reaction tower.

The apparatus described above can be used in batch or continuous processing as required. When used in batch processing, a sufficient amount of methanol is added to the reaction solution and chlorine is continuously fed. When the hydrochloric acid concentration in the reaction solution reaches 30 to 35%, the acid begins to flow out of the reaction column in the gas phase. Therefore, the hydrochloric acid concentration in the absorption solution begins to rise. If the apparatus is used for a continuous reaction, a mixture of methanol and water is continuously fed into the reaction column, and at the same time hydrogen chloride is discharged from the continuous reaction column.

Considering the use of hydrochloric acid, its concentration must be as high as possible. Therefore, the reaction must be carried out in such a way that the concentration of hydrochloric acid in the reaction solution increases and the hydrochloric acid flows out from the reaction tower to the absorption tower. Since methanol in the reaction solution has fluid pressure, methanol flows out to the absorption tower together with hydrochloric acid and is absorbed into the absorption solution. Therefore, the absorption solution obtained from the absorption tower contains both hydrochloric acid and methanol. The presence of methanol in the absorption solution does not pose any hindrance when the produced hydrochloric acid is used to produce chlorine dioxide.

In a method for producing chlorine dioxide using sodium chlorate as a reactant described in US Pat. No. 4,081,520, methanol is used as a reducing agent in a sulfur acidic solution. In the production of chlorine dioxide according to the invention, chlorine dioxide is quiesced from sodium chlorate and hydrochloric acid in the presence of a reducing agent. A solution of hydrochloric acid and methanol produced by the method disclosed with respect to FIG. 1 is used as the hydrochloric acid and reducing agent necessary for the reaction.

When producing chlorine dioxide, it is possible to use the hydrochloric acid produced according to the invention,
The reaction solution containing methanol used as a reducing agent together with hydrochloric acid circulating in the reaction tower shown at point A in Figure 1, and the gas phase mixture of hydrochloric acid and methanol flowing out from the reaction tower (point B in Figure 1) ) can be used. In the latter case, the gas phase mixture can be absorbed into a suitable stream recycled into the chlorine dioxide reactor to increase the hydrochloric acid concentration in the chlorine dioxide reactor. this is,
It is useful in carrying out the reaction for producing chlorine dioxide. Naturally, it is also possible to use the effluent hydrochloric acid solution shown at point C in FIG. 1 as the hydrochloric acid introduced into the chlorine dioxide reactor.

Experimental results show that in a completely closed apparatus, the reaction of chlorine and methanol shows a high yield as long as fresh solvent is used and the reaction solution does not contain a large amount of hydrochloric acid; It has been found that efficiency decreases as the concentration of hydrochloric acid in the solution increases to around 20%. In the present invention, based on the knowledge that the yield can be dramatically improved by applying light to the reaction mixture, the present invention is designed to easily obtain a hydrochloric acid concentration of 30% in the reaction mixture by irradiation with light. ing.

Examples of the present invention will be shown below.

Six tests were conducted, the first four of which were conducted without light irradiation. In Tests 5 and 6, light was applied during the reaction. All tests were carried out at a temperature of 60-70°C, in particular 63-68°C. During the test, the reaction temperature typically rose about 5°C in 7 hours. The test results are shown in the table below.

[0023]

[Table 1]

In tests 1 through 4 of the table above, chlorine was observed to pass through the apparatus of FIG. 1 without reaction. In the tests shown in Figures 5 and 6, no such passage of chlorine was observed. The chlorine feed rate was varied between 7.5 and 10 g/min. In all tests, nitrification occurred at the beginning of the test. At the end of the reaction, unreacted chlorine remained in the gas space in all tests. No unreacted chlorine could be observed in the material balance. Therefore, the percentage yield of hydrochloric acid relative to the amount of chlorine supplied is:
It is somewhat smaller. The yield-improving effect of light is clear from the difference in yield between Tables 1 to 4 and Tables 5 and 6.

[0025]

As described above, the present invention provides a method for producing hydrochloric acid that does not use hydrogen gas and does not require the use of a special high-temperature resistant burner. Further, according to the present invention, it is possible to provide a method for producing hydrochloric acid that can obtain a highly concentrated aqueous solution of hydrochloric acid. Further, according to the present invention, it is possible to provide a method for producing chlorine dioxide without using a large amount of hydrochloric acid.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of an apparatus used to implement the present invention.

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

Claims (4)

[Claims] Claim 1: Hydrochloric acid or a solution of hydrochloric acid and methanol is produced by reacting chlorine and methanol by exposing a reaction solution containing chlorine and methanol in a reaction tower to light at an elevated temperature. How to generate. 2. Hydrochloric acid produced by reacting chlorine and methanol, characterized in that light is applied to a reaction solution containing chlorine and methanol in a reaction tower in the presence of water and at an elevated temperature. A method of using a solution of hydrochloric acid and methanol, characterized in that the solution of methanol is used to produce chlorine dioxide from sodium chlorate in the presence of a reducing agent. 3. The method of claim 2, wherein the hydrochloric acid and reducing agent used in the chlorine dioxide production reaction are vapors of a mixture of hydrochloric acid and methanol flowing out from the reaction column. 4. The method of claim 2, wherein the hydrochloric acid and reducing agent used in the chlorine dioxide production reaction are a mixture of hydrochloric acid, methanol, and water.