JPS6240287B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing chlorosulfonic acid by reacting HCl in a chlorosulfonic acid solution containing SO ₃ , and provides a method particularly suitable for a continuous method.

Conventionally, a method for producing chlorosulfonic acid by a so-called liquid phase method, in which HCl is reacted in a chlorosulfonic acid solution in which SO ₃ gas or SO ₃ liquid has been absorbed or dissolved, is known. For example, it is published on page 466 of "Complete Works of Manufacturing Process Diagrams" published by Kagaku Kogyosha on September 10, 1964. Therefore, such liquid phase methods, especially when carried out in a continuous manner,
Compared to the batch type, the corrosion of the equipment, including the reactor, is extremely significant. The reason for this is presumed to be due to the state of HCl content in the chlorosulfonic acid solution. That is, in the case of a batch method, since HCl is introduced after initially containing a large amount of SO ₃ in chlorosulfonic acid, most of the reaction proceeds in the chlorosulfonic acid solution containing SO ₃ . The chlorosulfonic acid solution contains HCl only for a very short time at the end of the reaction. For this reason, batch-type equipment is generally made of steel, but corrosion is within an acceptable range. On the other hand, in the case of a continuous system, excess chlorosulfonic acid solution containing SO ₃ is generally used.
HCl is introduced and reacted, and the resulting chlorosulfonic acid solution is taken out, and most of the chlorosulfonic acid solution is reused for SO ₃ absorption while containing HCl. Therefore, continuous equipment has the disadvantage that ordinary metal materials (steel, chrome steel, nickel alloy, etc.) are subject to extremely high corrosion, and the resulting chlorosulfonic acid solution is contaminated with impurities such as iron.

Therefore, continuous equipment requires glass lining, pure glass, fluorine resin (coating),
Non-metallic device materials such as ceramics should be used. However, such non-metallic materials are generally expensive and easily damaged; for example, non-metallic heat exchangers have a large heat transfer area, making them expensive, and Teflon-based resin coatings have problems such as liquid penetration and peeling. There are problems, and the current situation is that non-metallic materials that can withstand continuous use are not available for pumps and the like. Therefore, if continuous production equipment for chlorosulfonic acid using a liquid phase method can be manufactured from metal materials as much as possible, it will be inexpensive and easy to manufacture, and it will also be easy to maintain, which is industrially advantageous and the most desirable. This is what is requested.

As a result of intensive research in order to satisfy the above-mentioned needs, the present inventors have found that in the production process of chlorosulfonic acid using a liquid phase method, a specific reaction method is carried out by introducing HCl into a chlorosulfonic acid solution containing SO ₃ . By dividing the range into at least two stages, the intended purpose was achieved. According to the invention SO ₃
HCl gas is introduced into the chlorosulfonic acid solution in which SO 3 has been dissolved and absorbed, and most of the reaction is carried out within the range where the SO ₃ remains, and a predetermined amount of the resulting crude chlorosulfonic acid solution is circulated to A method for producing chlorosulfonic acid is provided, which comprises a first step of dissolving and absorbing _{SO 3} and a second step of introducing HCl gas into the remainder of the crude chlorosulfonic acid solution to complete the SO ₃ reaction. Ru.

According to the liquid phase method for producing chlorosulfonic acid, the chlorsulfonic acid solution contains SO ₃ gas or SO ₃
It absorbs and dissolves liquids, and generally contains 2 to 15% by weight. In the present invention, first, HCl gas is introduced into a chlorosulfonic acid solution containing SO ₃ and
It is extremely important to carry out most of the reaction in a range where SO ₃ remains. Furthermore, in the present invention, it is extremely important to circulate a predetermined amount of the crude chlorosulfonic acid solution obtained in this way to absorb and dissolve SO ₃ . That is, in the present invention, absorption and dissolution of SO ₃ into the chlorosulfonic acid solution described above, introduction and reaction of HCl into the chlorosulfonic acid solution containing the SO ₃ , and circulation of the obtained crude chlorosulfonic acid solution In the first step, the chlorosulfonic acid solution is in a state containing SO ₃ and hardly reaches a state containing HCl.

Therefore, the equipment and equipment in the first process, such as the SO ₃ absorption tower for the chlorosulfonic acid liquid, the HCl reaction tower, the circulation pipe, the heat exchanger, the pump, and the piping, are almost completely free from corrosion even if they are all made of metal. Permissible. In addition, in the first step, the reaction performed by introducing HCl gas into the SO ₃ -containing chlorosulfonic acid solution is as follows:
It is necessary to increase the SO ₃ as much as possible within the remaining range, but generally 80 to 99 wt% of SO ₃ , especially 90
It is preferable to react up to 95 wt%. If the reaction to SO ₃ in the first step is less than 80wt%, then the reaction of the remaining 20wt% or more to SO ₃ must be completed in the second step, which increases the plant scale of the second step. undesirable for. That is, as described above, in the present invention, all the equipment for the first step can be made of metal materials, so it is advantageous to make the equipment as large as possible because it is industrially cheaper and easier to manufacture. On the other hand, in the first step, it is difficult to automatically control the reaction of HCl with SO ₃ to a range where SO ₃ remains at 99 wt% or more, so the obtained chlorosulfonic acid solution will be in a state containing HCl. This is not desirable as it may cause corrosion.

The metal material used for the equipment in the first process is not particularly limited as long as it is a corrosion-resistant metal, such as steel, chrome steel,
Nickel alloys and the like may be used, but austenitic stainless steel is most preferred.

Next, in the present invention, the remainder of the crude chlorosulfonic acid liquid obtained in the first step that has been supplied to the circulating fluid (corresponding to the amount of the produced chlorosulfonic acid liquid) is led to the second step and HCl gas is introduced. to complete the reaction with _SO3 . That is, in the second step of the present invention, the remaining SO ₃ of the crude chlorosulfonic acid solution is 1 to 20 wt%, especially 3 to 20 wt%.
Chlorosulfonic acid is produced by reacting 10wt% with HCl. However, in chlorosulfonic acid solution containing SO ₃ ,
When HCl gas is introduced to complete the reaction of 100 wt% SO ₃ , a chlorosulfonic acid solution containing HCl is often obtained. Therefore, the equipment for the second step that may come into contact with such HCl-containing chlorosulfonic acid may be made of a metal material, but a non-metal material is preferred. Generally, coating with fluororesin is preferably employed. Fluorine resins include tetrafluoroethylene polymer, tetrafluoroethylene/hexafluoropropylene copolymer, tetrafluoroethylene-perchloroalkyl ether copolymer,
Fluorinated ethylene-ethylene copolymers are most preferred, followed by trifluorinated chlorinated ethylene polymers. Among these lining methods, the most preferred are loose lining in which the resin sheet is simply inserted into the can metal without bonding, or lining by a bolt method, followed by adhesive lining and coating methods, in that order. In addition, glass lining, pure glass, porcelain, etc. can also be used.

As described above, in the first step, the method of the present invention introduces HCl gas into the SO ₃ -containing chlorosulfonic acid solution and causes the reaction to occur as much as possible while the SO ₃ remains. It is desirable to concentrate as many devices as possible in the first step and to make the second step device as small as possible. Thus, the present invention can provide a continuous method for producing chlorosulfonic acid by a liquid phase method that uses inexpensive equipment, is easy to manufacture, and is easy to maintain. Furthermore, pyrosulfuryl chloride, which is produced as a by-product in the SO ₃ -containing chlorosulfonic acid solution in the first step, can be easily converted to chlorosulfonic acid by the HCl reaction in the second step. i.e. generally at a temperature of 70-100℃
Pyrosulfuryl chloride in chlorosulfonic acid solution is removed by contacting with HCl gas for over 10 minutes.
The concentration can be lowered to 0.5% or less.

A typical flow sheet for the method of the present invention is shown. In Fig. 1, SO ₃ gas 2 is introduced into the chlorosulfonic acid liquid in a packed absorption tower 1 to absorb and dissolve it, and after heat is removed in a cooler 11, it is led to a packed reaction tower 3 where HCl gas is Introducing 4
The first step is to perform most of the reaction in a range where SO ₃ remains, remove heat from the resulting crude chlorosulfonic acid liquid 5 in a cooler 12, and then circulate a predetermined amount 6 of it to the absorption tower 1. On the other hand, in a second step, the remainder 7 of the crude chlorosulfonic acid liquid 5 is introduced into a packed reaction tower 8 to complete the reaction by introducing HCl gas 9, and then cooled in a cooler 13 to produce chlorosulfonic acid 10. Become. In Figure 2, using a chlorosulfonic acid solution containing SO ₃ solution 2', most of the reaction is carried out by introducing HCl gas 4 into the reaction tower 3 in the same manner as in the flow of Figure 1. a first step of circulating a predetermined amount 6 of the crude chlorosulfonic acid liquid 5;
In addition, a second step is performed in which the remaining portion 7 of the crude chlorosulfonic acid 5 is introduced into a reaction tower 8 with HCl gas 9 to complete the reaction to produce chlorosulfonic acid 10. Fig. 3 shows another embodiment of the second step, in which the crude chlorosulfonic acid solution derived from the first step is brought into contact with HCl gas in reaction towers 8', 8'' and 8 in order to complete the reaction. That is, the crude chlorosulfonic acid liquid 7 shown in FIG. 3 is introduced into a packed reaction column 8', and then passed through a liquid column type reaction column 8'' and further into a reaction column 8 of the same type.
On the other hand, HCl gases 9' and 9'' are in the reaction column 8'', respectively.
and 8, and then passed to the reaction column 8'. In the second step, the SO ₃ of the crude chlorosulfonic acid solution is brought into contact with HCl in two or more stages to complete the reaction and convert the by-product pyrosulfuryl chloride into chlorosulfonic acid. In addition, it is easy to effectively utilize HCl gas so that the waste HCl gas 9 in the reaction tower 8' becomes zero, and furthermore, the chlorosulfonic acid liquid 7' flowing out of the reaction tower 8' contains a trace amount of SO _{3 .} accompanied by,
The product of chlorosulfonic acid liquid 10 obtained by reacting with HCl in reaction towers 8'' and 8 has no SO ₃ residue and almost no by-product pyrosulfuryl chloride.Furthermore, as shown in FIG. As shown, HCl can be used 100% effectively by circulating the HCl gas 9 discharged from the second step to the reaction column 4. Therefore, the liquid column column type reaction in the second step HCl in columns 8″ and 8
By operating in excess, the reaction rate of HCl gas-liquid contact can be increased, and the reaction from pyrosulfuryl chloride to chlorosulfonic acid in the chlorosulfonic acid solution can be favorably maintained in equilibrium. can.

Examples of the present invention are shown below, but the present invention is not limited thereto.

Example 1 According to the flow sheet shown in Figure 1, the equipment for the first step was made of SUS316, and the equipment for the second step was made of steel with loose lining of Teflon. Manufactured the manufacturing equipment. Note that the weight of the equipment for the second step is equivalent to 0.07 for the weight of the equipment for the first step of 1, and most of the equipment is concentrated in the first step.

Using such equipment, a chlorosulfonic acid solution containing 7% by weight of SO ₃ is converted into HCl in the reaction tower of the first step.
A predetermined amount of the crude chlorosulfonic acid liquid obtained by introducing gas and reacting 93wt% of the SO ₃ is circulated to the SO ₃ absorption tower, and the remaining crude chlorosulfonic acid liquid is converted into HCl in the reaction tower of the second step. Gas was introduced and SO ₃ reaction was carried out to obtain 1500 Kg/hr of chlorosulfonic acid.
The Fe content in this product's chlorsulfonic acid solution is 0.3ppm.
It was hot.

For comparison, when the reaction was carried out by introducing HCl gas equivalent to 102 wt% relative to SO ₃ in the reaction tower of the first step, the Fe content in the product chlorosulfonic acid liquid was 35 ppm. There was corrosion in the first process equipment.

[Brief explanation of the drawing]

1, 2, 3, and 4 are flow sheets showing typical embodiments of the present invention. 1... Packed absorption tower, 2... SO ₃ gas, 3
...Packaged reaction column, 4...HCl gas, 5...
Crude chlorosulfonic acid liquid, 6... Circulating chlorosulfonic acid liquid, 7... Transferred chlorosulfonic acid liquid, 8,
8'... Reaction column with packing, 8'', 8... Liquid column type reaction column, 9, 9', 9''... HCl gas, 10...
Produced chlorosulfonic acid liquid, 11, 12, 13...
Heat exchanger.

Claims (1)

[Claims] 1. Introducing HCl gas into a chlorosulfonic acid solution containing SO ₃ to react 80 wt% to 99 wt% of the SO ₃ , and circulating a predetermined amount of the obtained crude chlorosulfonic acid. A method for producing chlorosulfonic acid, which comprises a first step in which SO ₃ is dissolved and absorbed, and a second step in which HCl gas is introduced into the remainder of the crude chlorosulfonic acid to complete the reaction. 2. The method for producing chlorosulfonic acid according to claim 1, wherein in the first step, 90 to 97 wt% of SO ₃ is reacted. 3. The method for producing chlorosulfonic acid according to claim 1, wherein the equipment material for the first step is a metal, and the equipment material for the second step is a nonmetal. 4. The method for producing chlorosulfonic acid according to claim 3, wherein the metal material is austenitic stainless steel. 5. The method for producing chlorosulfonic acid according to claim 3, wherein the nonmetallic material is a fluorine-containing resin.