JP2014073449A - Carbonyl sulfide absorbent and method of processing carbonyl sulfide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbonyl sulfide absorbent and a method of processing carbonyl sulfide which enable carbonyl sulfide to be inexpensively and easily processed.SOLUTION: Carbonyl sulfide-containing gas is contacted with an absorbent containing amine indicated by the following general formula (1). Here, (n) is an integer of 1 to 4. Ris a hydrogen group or a methyl group. When n is 2 or larger, Rbonding to different carbon each may be the same group, or may also be a different group. Ris a group bonding to an optional position of an aromatic ring, and is selected from the hydrogen group, an alkyl group of the carbon number of 1-6, an aryl group, a substituted aryl group, a halogen group and an alkoxy group of the carbon number of 1-4. The Rbonding to a different position of the aromatic ring each may be the same group, or may also be a different group.

Description

  The present invention relates to a carbonyl sulfide absorbent and a method for treating carbonyl sulfide. More specifically, the present invention relates to a sulfur sulfide suitable for treating a high concentration of carbonyl sulfide or removing a trace amount of carbonyl sulfide contained in an industrial gas. The present invention relates to a carbonyl absorbent and a method for treating carbonyl sulfide.

  Carbonyl sulfide has attracted attention as an anisotropic dry etching gas for organic hard masks in the semiconductor multilayer resist process. For this type of semiconductor manufacturing application, high-purity carbonyl sulfide with few impurities is used.

Carbonyl sulfide is not classified as toxic or flammable under the High Pressure Gas Safety Law, but is classified as toxic in the UL standard, so it is consumed without being taken out of the system from the carbonyl sulfide production line, or N _It is filled in a cylinder or the like as a mixed gas diluted with _two gases and taken out and consumed. In such a case, it may be necessary to treat high-concentration carbonyl sulfide remaining in the carbonyl sulfide production line, for example, with periodic inspections. In addition, it may be necessary to treat high-concentration carbonyl sulfide remaining in the piping in accordance with cylinder replacement or the like.

  In addition, carbonyl sulfide is a by-product of iron production, petroleum refining, and the like, and is also contained in industrial gases such as coal gas, water gas, and blast furnace gas, and exhaust gas of automobiles and the like. In these, carbonyl sulfide is present in the gas as a trace component of several ppm to 1%, but considering the toxicity and catalyst poison, etc., a trace amount of sulfide contained in the gas. Removal of the carbonyl is performed.

  For example, Patent Document 1 discloses a method for removing carbonyl sulfide from a sulfur-containing industrial gas using an N-alkylalkanolamine aqueous solution. Patent Document 2 discloses a method for removing carbonyl sulfide from a sulfur-containing industrial gas using a specific secondary alkylamine or tertiary alkylamine. Patent Document 3 discloses a method for removing carbonyl sulfide from a sulfur-containing industrial gas using morpholine.

JP-A-53-138403 JP 56-136620 A Japanese Patent Publication No. 48-16422

  When the carbonyl sulfide is treated with N-alkylalkanolamine as in Patent Document 1, white smoke may be produced during the treatment, and a strange odor may be produced from the treatment liquid. This is presumably because various sulfur-containing cracked gases are generated during the treatment. In other words, since there is a sulfur-containing gas that is not sufficiently collected, there is a possibility that the treatment process becomes complicated.

  When a specific secondary alkylamine or tertiary alkylamine is used to treat carbonyl sulfide as in Patent Document 2, there is a problem that the treatment speed is slow. This is presumably because the reactivity between a specific amine and carbonyl sulfide is low.

  In Patent Document 3, a solid reaction product of morpholine and carbonyl sulfide is hydrolyzed to regenerate morpholine and reuse it for the treatment of carbonyl sulfide. Regeneration of morpholine from a solid reaction product requires high temperature and pressure conditions and is costly.

  Moreover, each method of patent documents 1-3 removes carbonyl sulfide as a trace component in gas, and does not process high concentration carbonyl sulfide.

  The problem to be solved by the present invention is to provide a carbonyl sulfide absorbent and a carbonyl sulfide treatment method capable of treating carbonyl sulfide easily and inexpensively.

（ただし、ｎは、１から４の整数である。Ｒ_１は、水素基またはメチル基である。ｎ≧２の場合には、異なる炭素に結合するＲ_１同士は、同じ基であっても良いし、異なる基であっても良い。Ｒ_２は、芳香環の任意の位置に結合する基であり、水素基、炭素数１〜６のアルキル基、アリール基、置換アリール基、ハロゲン基、炭素数１〜４のアルコキシ基から選択される。芳香環の異なる位置に結合するＲ_２同士は、同じ基であっても良いし、異なる基であっても良い。） In order to solve the above problems, the carbonyl sulfide absorbent according to the present invention is characterized in that it contains an amine represented by the following general formula (1).

(However, n is an integer of 1 to 4. R ₁ is a hydrogen group or a methyl group. When n ≧ 2, R ₁ bonded to different carbons may be the same group. R ₂ is a group bonded to an arbitrary position of the aromatic ring, and is a hydrogen group, an alkyl group having 1 to 6 carbon atoms, an aryl group, a substituted aryl group, a halogen group, It is selected from an alkoxy group having 1 to 4 carbon atoms, and R ₂ bonded to different positions of the aromatic ring may be the same group or different groups.

  In this case, the carbonyl sulfide absorbent preferably further contains a solvent. The solvent is preferably a polar aprotic solvent or a glycol solvent. Moreover, it is preferable that the boiling point of a solvent is 150 degreeC or more. As such a solvent, dimethyl sulfoxide is mentioned as a suitable thing.

  The gist of the carbonyl sulfide treatment method according to the present invention is to bring a gas containing carbonyl sulfide into contact with an absorbing solution containing a carbonyl sulfide absorbent.

  The gas containing carbonyl sulfide may contain 3% by volume or more of carbonyl sulfide.

  In the method for treating carbonyl sulfide according to the present invention, it is preferable to precipitate and remove a salt produced by the reaction of carbonyl sulfide with the amine represented by the general formula (1).

  According to the carbonyl sulfide absorbent and the method for treating carbonyl sulfide according to the present invention, the amine represented by the general formula (1) is highly reactive, and a salt with carbonyl sulfide is quantitatively formed. Moreover, the crystallinity of the salt is high and it is stable as a solid, and the by-product of the sulfur-containing cracked gas is suppressed during processing. Then, after the treatment with carbonyl sulfide, it is sufficient to recover a stable solid salt. Therefore, the treatment of carbonyl sulfide can be easily performed at low cost.

  In this case, if the carbonyl sulfide absorbent further contains a solvent, blockage by the salt at the supply port for supplying carbonyl sulfide is easily suppressed, so that the treatment of carbonyl sulfide is performed stably. If the solvent is a polar aprotic solvent or a glycol solvent, the generated salt has a high solubility, so that blockage by the salt at the supply port for supplying carbonyl sulfide is more easily suppressed. When the boiling point of the solvent is 150 ° C. or higher, the evaporation and outflow of the solvent due to the air flow accompanying the supply of carbonyl sulfide is suppressed, so that the treatment of carbonyl sulfide is stably performed. When dimethyl sulfoxide is used as the solvent, the solubility of the salt to be produced is particularly high, so that blockage by the salt at the supply port for supplying carbonyl sulfide is particularly easily suppressed. Moreover, since the boiling point is high, it is easy to suppress the vaporization outflow of the solvent by the air flow accompanying supply of carbonyl sulfide. Even when 3% by volume or more of carbonyl sulfide is contained in the gas containing carbonyl sulfide, the amine represented by the above general formula (1) has high reactivity, and is quantitatively a salt with carbonyl sulfide. Is formed. Moreover, the by-product of sulfur-containing cracked gas is also suppressed.

It is a flowchart of the processing method of the carbonyl sulfide which concerns on one Embodiment of this invention.

  Next, an embodiment of the present invention will be described in detail.

  The carbonyl sulfide absorbent according to the present invention comprises a specific amine. In addition, the method for treating carbonyl sulfide according to the present invention (hereinafter sometimes referred to as “the present treatment method”) includes a gas containing carbonyl sulfide and an absorbing solution containing a specific amine (the carbonyl sulfide absorbent according to the present invention is used). (Absorbing liquid contained). In this case, since carbonyl sulfide and a specific amine react, ammonium thiocarbamate is formed in the absorbing solution.

  The salt produced in this treatment method remains in the salt form and is discarded or used for other purposes. When the produced salt is dissolved in the absorbing solution, it is discarded as it is or used for other purposes. If a part of the generated salt is precipitated from the absorbent, after solid-liquid separation as necessary, only the solid or both the solid and the solution are discarded or others Used for applications. If only solids are discarded or used for other applications, the solution can be reused for subsequent carbonyl sulfide treatment.

Examples of the gas containing carbonyl sulfide include a gas composed of carbonyl sulfide alone, a mixed gas obtained by mixing a dilution gas with a gas composed of carbonyl sulfide alone, and a gas containing a relatively high concentration of carbonyl sulfide. Examples include industrial gases containing carbonyl sulfide. Examples of the dilution gas include N ₂ , helium, and air. This treatment method can be applied to a gas containing a high concentration of carbonyl sulfide, and can also be applied to a gas containing a low concentration of carbonyl sulfide.

  Examples of the gas containing a high concentration of carbonyl sulfide include exhaust gas during the production of carbonyl sulfide, exhaust gas during etching using carbonyl sulfide, chemical synthesis, and the like. During the production of carbonyl sulfide, it may be necessary to discharge the gas remaining in the carbonyl sulfide production line in accordance with periodic inspections of the apparatus. In addition, when carbonyl sulfide is used, it may be necessary to discharge the gas remaining in the piping due to cylinder replacement or the like. For example, in such cases, it may be necessary to treat a gas containing a high concentration of carbonyl sulfide. In these, carbonyl sulfide is contained in the gas by several% (about 3%) to 100%.

  Examples of the gas containing a low concentration of carbonyl sulfide include industrial gas and exhaust gas from automobiles. Carbonyl sulfide is produced as a by-product in iron manufacturing and petroleum refining. For this reason, it is contained also in industrial gas, such as coal gas, water gas, and blast furnace gas. It is also included in exhaust gas from automobiles. In these, carbonyl sulfide is present in the gas as a trace component of several ppm to 1%, but considering the toxicity and catalyst poison, etc., a trace amount of sulfide contained in the gas. Removal of the carbonyl is performed.

（ただし、ｎは、１から４の整数である。Ｒ_１は、水素基またはメチル基である。ｎ≧２の場合には、異なる炭素に結合するＲ_１同士は、同じ基であっても良いし、異なる基であっても良い。Ｒ_２は、芳香環の任意の位置に結合する基であり、水素基、炭素数１〜６のアルキル基、アリール基、置換アリール基、ハロゲン基、炭素数１〜４のアルコキシ基から選択される。芳香環の異なる位置に結合するＲ_２同士は、同じ基であっても良いし、異なる基であっても良い。） The specific amine contained in the absorbing solution is composed of the following general formula (1).

(However, n is an integer of 1 to 4. R ₁ is a hydrogen group or a methyl group. When n ≧ 2, R ₁ bonded to different carbons may be the same group. R ₂ is a group bonded to an arbitrary position of the aromatic ring, and is a hydrogen group, an alkyl group having 1 to 6 carbon atoms, an aryl group, a substituted aryl group, a halogen group, It is selected from an alkoxy group having 1 to 4 carbon atoms, and R ₂ bonded to different positions of the aromatic ring may be the same group or different groups.

  In the general formula (1), the alkyl group having 1 to 6 carbon atoms may be a linear alkyl group or a branched alkyl group. Examples of the substituent for the substituted aryl group include an alkyl group, a halogen group, and an alkoxy group.

  Specific amines contained in the general formula (1) include benzylamine, 2-phenylethylamine, 3-phenyl-1-propylamine, 2-bromobenzylamine, 1-phenylethylamine, 4-bromo-α-methyl. Examples include benzylamine, 4-n-butylbenzylamine, 2- (4-bromophenyl) ethylamine, 2,5-dimethoxyphenethylamine.

  As shown in the above general formula (1), the specific amine has a primary amine group bonded to the tip of a carbon chain of an appropriate length extending from the aromatic ring, so that it is reactive with carbonyl sulfide. Excellent and quantitatively a salt with carbonyl sulfide (ammonium thiocarbamate) is formed. And the salt produced | generated from having an aromatic ring with respect to the primary amine group couple | bonded with the front-end | tip of the carbon chain of suitable length is obtained as a solid, and is excellent in crystallinity. In addition, the generated salt is stable as a solid, and the by-product of the sulfur-containing cracked gas is suppressed. For this reason, the treatment of carbonyl sulfide is excellent in workability because it is sufficient to recover a stable solid salt. Therefore, the treatment of carbonyl sulfide can be easily performed at low cost. The specific amine is preferably in a liquid state at room temperature (25 ° C.) from the viewpoint of excellent separability from the generated salt (can be solid-liquid separated).

In a specific amine, the length of the carbon chain extending from the aromatic ring and bonded to the primary amine group is preferably shorter from the viewpoint that the salt produced by the reaction with carbonyl sulfide is more excellent in crystallinity. Specifically, in the general formula (1), n is preferably 1 to 2. More preferably, n is 1. In addition, in a specific amine, a group bonded to the carbon adjacent to the primary amine group (general formula (1) to the carbon adjacent to the amine group from the viewpoint of higher reactivity with carbonyl sulfide). R ₁ ) to be bonded is preferably a hydrogen group. Accordingly, particularly preferred amines include benzylamine and 2-phenylethylamine.

  The absorbing solution may contain only a specific amine, but from the viewpoint of easily suppressing clogging with a salt at the supply port for supplying carbonyl sulfide, the absorbing solution may further contain a solvent. preferable. When a gas containing a high concentration of carbonyl sulfide is treated, clogging is particularly likely to occur. Therefore, when treating a gas containing a high concentration of carbonyl sulfide, it is highly significant that a solvent is contained in the absorbing solution. It is preferable that the solvent is easily mixed with a specific amine. Moreover, it is preferable that the salt to be produced is dissolved. From the viewpoint that it is preferable to dissolve the salt to be formed, a solvent having a salt solubility at 25 ° C. (normal temperature) of 1% or more (that is, a saturated solution concentration of 1% or more) is preferable. More preferably, the solvent has a solubility of 5% or more.

Examples of the solvent include water alone or an aqueous solvent or an organic solvent containing water. Since the specific amine has an aromatic ring and an alkyl chain, an organic solvent is more preferable in consideration of the ease of mixing the specific amine and the solubility of the generated salt. Among organic solvents, glycols such as polar aprotic solvents and ethylene glycols represented by HO (CH ₂ CH ₂ O) _n H (n = 1 to 14) from the viewpoint of high solubility of the generated salt. System solvents are preferred. Among polar aprotic solvents, dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) are preferred from the viewpoint of higher solubility of the salt produced. Of the glycol solvents, ethylene glycols represented by HO (CH ₂ CH ₂ O) _n H (n = 1 to 4) are preferable. Of these, dimethyl sulfoxide (DMSO) is preferred from the viewpoint of the highest solubility of the salt produced.

  The solvent preferably has a boiling point of 150 ° C. or higher from the viewpoint of suppressing the outflow of the solvent due to the air flow accompanying the supply of carbonyl sulfide. More preferably, it is 160 degreeC or more, More preferably, it is 180 degreeC or more. Since the outflow of the solvent by the air flow accompanying the supply of carbonyl sulfide is suppressed, the treatment of carbonyl sulfide can be performed stably.

  When dimethyl sulfoxide (DMSO) is used as the solvent, since the solubility of the resulting salt is particularly high, blockage by the salt at the supply port for supplying carbonyl sulfide is particularly easily suppressed. Moreover, since the boiling point is high, it is easy to suppress the outflow of the solvent by the air flow accompanying the supply of carbonyl sulfide.

  When the absorption liquid contains a solvent, the concentration of the specific amine in the absorption liquid is within the range of 1 to 80% by mass in consideration of the reactivity with carbonyl sulfide and the solubility of the generated salt. Preferably there is. More preferably, it exists in the range of 5-50 mass%.

  The treatment of carbonyl sulfide may be performed at room temperature or under heating conditions. Since the reaction between the specific amine and carbonyl sulfide is an exothermic reaction, when the carbonyl sulfide is treated at a relatively low temperature such as room temperature, it is preferable to cool during the treatment.

  The method for treating carbonyl sulfide according to the present invention can be performed, for example, according to the flowchart shown in FIG. An example of a method for treating carbonyl sulfide will be described with reference to FIG.

  As shown in FIG. 1, a gas containing carbonyl sulfide (COS) (hereinafter sometimes referred to as COS gas) is introduced into an absorption tank 3 through a COS gas line 1. A dilution gas line 2 is connected to the COS gas line 1, and the COS gas is diluted with the dilution gas as necessary. The COS gas introduced into the absorption tank 3 is brought into contact with the absorption liquid supplied to the absorption tank 3 in the absorption tank 3. The absorbing liquid contains the specific amine. Further, the absorbing liquid contains a solvent as necessary. Therefore, in the absorption tank 3, ammonium thiocarbamate is formed. The formed ammonium thiocarbamate is conveyed to the solid-liquid separation tank 6 through the liquid discharge line 5 together with the absorbing liquid. The dilution gas introduced into the absorption tank 3 is discharged to the outside through the gas discharge line 4. In the solid-liquid separation tank 6, solid-liquid separation is performed, and solids are discharged from the solid discharge line 8. The solution component is circulated into the absorption tank 3 through the liquid circulation line 7 and used again as an absorption liquid. An amine supply line 9 is connected to the liquid circulation line 7, and the specific amine is added as necessary.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Example 1
Absorption tanks were installed in two stages, and 20 g (0.187 mol) of benzylamine and 50 ml of dimethyl sulfoxide (DMSO) were placed in each absorption tank. Next, a mixed gas of carbonyl sulfide (COS) gas (68 ml / min.) And nitrogen gas (100 ml / min.) Was supplied to the first stage absorption tank for 30 minutes using a blowing tube. The exhaust gas from the first-stage absorption tank was supplied to the second-stage absorption tank, and carbonyl sulfide gas that could not be absorbed by the first-stage absorption tank was absorbed. With the supply of the mixed gas, the color of the absorbing solution changed from colorless to green, and then a solid (white powder) was deposited in the first-stage absorbing solution. During the mixed gas supply, no white smoke was observed.

  After the supply of the mixed gas, the amount of weight increase in each absorption tank was measured, and the amount of absorption of carbonyl sulfide gas was measured. The weight increase of the first stage absorption tank is 5.42 g (0.090 mol in terms of COS), and the weight increase of the second stage absorption tank is 2.71 g (0.045 mol in terms of COS), which is a total of 8. It was 13 g (0.135 mol in terms of COS). Further, after the supply of the mixed gas was completed, the blow tube was examined. As a result, solid matter was found attached to the tip of the blow tube, but the gas flow rate was stable from beginning to end, so the blow tube was not blocked. Inferred.

  If the total amount of weight increase in the absorption tank is carbonyl sulfide and the total amount of carbonyl sulfide reacts with benzylamine, benzylamine and carbonyl sulfide form a 2: 1 salt, so the first absorption tank The reaction rate of benzylamine is calculated as (0.090 × 2 ÷ 0.187) × 100 = 96%. That is, it is presumed that the reaction proceeds almost quantitatively by using benzylamine.

  Further, when the exhaust gas in the second-stage absorption tank was analyzed by gas chromatography, no by-product of the sulfur-containing cracked gas was confirmed. That is, the produced salt is stable as a solid, and after the treatment with carbonyl sulfide, it is only necessary to recover a stable solid salt, so that the workability is excellent. Therefore, the treatment of carbonyl sulfide can be easily performed at low cost.

(Comparative Example 1)
The same procedure as in Example 1 was conducted except that 10 g (0.164 mol) of ethanolamine and 50 ml of dimethyl sulfoxide (DMSO) were added to each absorption tank. With the supply of the mixed gas, white smoke was generated, but no solid deposition was observed. The absorbing solution remained homogeneous throughout.

  After the supply of the mixed gas, the amount of weight increase in each absorption tank was measured, and the amount of absorption of carbonyl sulfide gas was measured. The weight increase of the first-stage absorption tank is 5.16 g (0.086 mol in terms of COS), and the weight increase of the second-stage absorption tank is 3.26 g (0.054 mol in terms of COS), a total of 8. The amount was 42 g (0.140 mol in terms of COS).

  If the total amount of weight increase in the absorption tank is carbonyl sulfide and the total amount of carbonyl sulfide reacts with ethanolamine, the first stage is calculated when ethanolamine and carbonyl sulfide form a 2: 1 salt. The reaction rate of ethanolamine in the absorption tank is calculated as (0.086 × 2 ÷ 0.164) × 100 = 105%.

  Further, the exhaust gas in the second-stage absorption tank has an odor peculiar to a sulfur compound, and when the exhaust gas was analyzed by gas chromatography, 6% of hydrogen sulfide was detected. Solid salt was recovered after the treatment of carbonyl sulfide because white smoke was generated during the supply of the mixed gas, solid salt was not deposited after the reaction, and sulfur-containing cracked gas was by-produced. This does not mean that it only has to be performed, but there is also a problem in the treatment of sulfur-containing cracked gas (exhaust gas), and it can be said that workability is poor.

(Example 2)
The absorption tank was installed in one stage, 10 g (0.093 mol) of benzylamine and 50 ml of water were added to the absorption tank, and the same procedure as in Example 1 was performed except that the mixed gas was supplied for 10 minutes. Immediately after the supply of the mixed gas, a solid was precipitated in the absorbent. During the mixed gas supply, no white smoke was observed.

  After the supply of the mixed gas, the amount of weight increase in the absorption tank was measured, and the absorption amount of the carbonyl sulfide gas was measured. The weight increase of the absorption tank was 0.60 g (0.010 mol in terms of COS). From the amount of salt (solid content) deposited, the amount of weight increase is too small, and it is assumed that the water in the absorption tank vaporized and flowed out with the supply of the mixed gas. Further, after the supply of the mixed gas was completed, the blow tube was examined. As a result, solid matter was found attached to the tip of the blow tube, but the gas flow rate was stable from beginning to end, so the blow tube was not blocked. Inferred.

(Example 3)
The same procedure as in Example 1 was conducted except that the absorption tank was installed in one stage, only 10 g (0.093 mol) of benzylamine was added to the absorption tank, and the mixed gas was supplied for 10 minutes. Immediately after the supply of the mixed gas, solids were deposited and the blowing pipe was almost blocked, and the flow of the mixed gas was deteriorated. However, generation of white smoke was not observed, and the exhaust gas could be treated.

(Comparative Example 2)
The absorption tank was installed in one stage, and the same procedure as in Example 1 was performed except that 10 g (0.095 mol) of diethanolamine and 50 ml of DMSO were added to the absorption tank and the mixed gas was supplied for 5 minutes. With the supply of the mixed gas, white smoke was generated, but no solid deposition was observed. The absorbing solution remained homogeneous throughout. After the supply of the mixed gas, the amount of weight increase in the absorption tank was measured, and the absorption amount of the carbonyl sulfide gas was measured. The weight increase of the absorption tank was 0.77 g (0.013 mol in terms of COS).

(Comparative Example 3)
The absorption tank was installed in one stage, and the same procedure as in Example 1 was performed except that 10 g (0.095 mol) of diglycolamine and 50 ml of DMSO were added to the absorption tank and the mixed gas was supplied for 5 minutes. With the supply of the mixed gas, white smoke was generated, but no solid deposition was observed. The absorbing solution remained homogeneous throughout. After the supply of the mixed gas, the amount of weight increase in the absorption tank was measured, and the absorption amount of the carbonyl sulfide gas was measured. The weight increase of the absorption tank was 1.40 g (0.023 mol in terms of COS).

(Comparative Example 4)
The absorption tank was installed in one stage, and the same procedure as in Example 1 was performed except that 10 g (0.133 mol) of methylethanolamine and 50 ml of DMSO were added to the absorption tank and the mixed gas was supplied for 5 minutes. With the supply of the mixed gas, white smoke was generated, but no solid deposition was observed. The absorbing solution remained homogeneous throughout. After the supply of the mixed gas, the amount of weight increase in the absorption tank was measured, and the absorption amount of the carbonyl sulfide gas was measured. The weight increase of the absorption tank was 0.95 g (0.016 mol in terms of COS).

  From Comparative Examples 1 to 4, no precipitation was observed in the absorption tank for all four alkanolamines. In this respect, the amine according to the present invention is clearly different. In addition, white smoke was generated in each of the four types of alkanolamines, and a by-product of sulfur-containing decomposition gas was confirmed. Also in this point, it is clearly different from the amine according to the present invention.

  Next, using the thiocarbamic acid ammonium salt (benzylthiocarbamic acid benzylammonium salt) obtained in Example 1, the solubility (25 ° C.) of the salt in each solvent was measured. The results are shown in Table 1. The boiling point of the solvent is also shown in Table 1.

  From Table 1, it can be said that each solvent of DMSO, DMF, diethylene glycol, and methanol is an excellent solvent from the viewpoint that the solubility of the salt is 1% or more and the solubility of the generated salt is high. DMSO and methanol are more excellent solvents from the viewpoint that the solubility of the salt is 2% or more and the solubility of the generated salt is higher. Furthermore, DMSO can be said to be a particularly excellent solvent from the viewpoint that the solubility of the salt is 5% or more and the solubility of the resulting salt is particularly high. On the other hand, since methanol has a boiling point of 100 ° C. or lower and is too low, it can be said that methanol easily flows out along with the supply gas containing COS. From this point of view, methanol cannot be said to be a preferred solvent, and DMSO, DMF, diethylene glycol and the like having a relatively high boiling point can be said to be excellent solvents. And considering these balances, it can be said that DMSO is a particularly excellent solvent.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

  The carbonyl sulfide absorbent and the carbonyl sulfide treatment method according to the present invention include exhaust gas treatment at the time of production of carbonyl sulfide, exhaust gas treatment at the time of etching treatment or chemical synthesis using carbonyl sulfide, and a trace amount contained in industrial gas. It can be applied to the treatment of carbonyl sulfide.

1 COS gas line 2 Dilution gas line 3 Absorption tank 4 Gas discharge line 5 Liquid discharge line 6 Solid-liquid separation tank 7 Liquid circulation line 8 Solid matter discharge line 9 Amine supply line

Claims (8)

A carbonyl sulfide absorbent comprising an amine represented by the following general formula (1):

(However, n is an integer of 1 to 4. R ₁ is a hydrogen group or a methyl group. When n ≧ 2, R ₁ bonded to different carbons may be the same group. R ₂ is a group bonded to an arbitrary position of the aromatic ring, and is a hydrogen group, an alkyl group having 1 to 6 carbon atoms, an aryl group, a substituted aryl group, a halogen group, It is selected from an alkoxy group having 1 to 4 carbon atoms, and R ₂ bonded to different positions of the aromatic ring may be the same group or different groups.   The carbonyl sulfide absorbent according to claim 1, further comprising a solvent.   The carbonyl sulfide absorbent according to claim 2, wherein the solvent is a polar aprotic solvent or a glycol solvent.   The carbonyl sulfide absorbent according to claim 2 or 3, wherein the solvent has a boiling point of 150 ° C or higher.   The carbonyl sulfide absorbent according to any one of claims 2 to 4, wherein the solvent is dimethyl sulfoxide.   A method for treating carbonyl sulfide, comprising bringing an absorbent containing the carbonyl sulfide absorbent according to any one of claims 1 to 5 into contact with a gas containing carbonyl sulfide.   The method for treating carbonyl sulfide according to claim 6, wherein the gas containing carbonyl sulfide contains 3% by volume or more of carbonyl sulfide.   The method for treating carbonyl sulfide according to claim 6 or 7, wherein a salt produced by the reaction of the carbonyl sulfide with the amine represented by the general formula (1) is precipitated and removed.

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