JP3515766B2 - Removal method of carbon disulfide - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for removing carbon disulfide known as an organic sulfur compound.

[0002]

2. Description of the Related Art Carbon disulfide (CS ₂ ) is a highly flammable, colorless, high-refractive-index liquid, which may explode when gasified and mixed with air. It is known to be high (explosion limit 1.3-50.0%). Therefore, for example, SF that becomes an obstacle when separating and purifying PFC (perfluoro compound)
_When decomposing ₆ with activated carbon, the sulfur liberated in the system reacts with activated carbon under a local temperature rise, and when CS ₂ is generated as a by-product, it is accumulated in the rectification column without being discharged. However, since the concentration proceeds during long-term operation, which increases the risk of explosion, it was necessary to suppress the generation or to appropriately remove it.

Therefore, it is an object of the present invention to provide a PFC purification process.
CS in the components remaining in the rectification tower at ₂, Specifically PF
SF in C mixture₆By the reaction of the decomposition components of
CS that occurred₂In a gas mixture such as a gas containing
₂Can be removed easily and efficiently with low energy
To provide.

[0004]

According to the present invention, a gas containing carbon disulfide and calcium hydroxide or soda lime are reduced in calcium hydroxide or soda lime while reducing the amount of water in the calcium hydroxide or soda lime. The above object is achieved by providing a method for removing carbon disulfide, which comprises contacting the carbon dioxide (CO ₂ ) in a state where the carbon dioxide (CO ₂ ) is removed or reduced.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The method for removing carbon disulfide according to the present invention will be described in detail below. As a method of removing or reducing carbon dioxide while reducing the amount of water in calcium hydroxide or soda lime, a method of cooling calcium hydroxide or soda lime and a heat treatment in an inert gas atmosphere, Examples thereof include a method of heat-treating calcium or soda lime in an inert gas atmosphere, a method of purging calcium hydroxide or soda lime with an inert gas, and the like.

As a preferred specific example of the method for cooling and heating calcium hydroxide or soda lime, calcium hydroxide or soda lime is cooled to around 0 ° C., and then an atmosphere of an inert gas such as nitrogen is used. The heat treatment is performed at 25 to 300 ° C. below. Carbon dioxide in calcium hydroxide or soda lime can be reduced by cooling calcium hydroxide or soda lime, and then heat treatment in an inert gas atmosphere allows calcium hydroxide or soda lime to be removed. The water content (OH content) can also be reduced. As is well known, calcium hydroxide is
With heating, water is released and becomes calcium oxide at 580 ° C. However, normal (eg commercially available) calcium hydroxide or soda lime is
When heat-treated at a temperature of 300 ° C., preferably 50 to 200 ° C., particularly preferably 60 to 100 ° C., for preferably 8 hours or less, particularly preferably 0.5 to 2.0 hours, calcium hydroxide or soda lime is obtained. The action of activating and adsorbing carbon disulfide (CS ₂ ) is increased. That is, calcium hydroxide or soda lime does not have a good adsorption effect even if the water content is usually contained or if the water content is reduced too much.

[0007] Calcium hydroxide and soda lime are known as carbon dioxide adsorbents, but the carbon dioxide taken in by calcium hydroxide or soda lime under the environment such as the atmosphere is calcium hydroxide or soda. It inhibits the adsorption of CS ₂ by lime. Furthermore, when calcium hydroxide or soda lime is heat-treated, it reacts with the carbon dioxide that has been taken in, and stable calcium carbonate is produced, thereby reducing the effect of CS ₂ adsorption. Therefore, by removing such carbon dioxide, the adsorption effect is improved. Examples of the method for removing carbon dioxide include a method of cooling calcium hydroxide or soda lime to a predetermined temperature. The specific temperature is -30 to 10 ° C, preferably -20 to 20 ° C.
It is necessary to cool to 3 ° C, particularly preferably to -10 to 0 ° C. By cooling in this manner to reduce the solubility of carbon dioxide, the carbon dioxide taken in is desorbed. This cooling is preferably performed in an inert gas atmosphere. As described above, after cooling to a predetermined temperature in an inert gas atmosphere, 25 to 300 in an inert gas atmosphere.
℃, preferably 50 to 200 ℃, more preferably 60 ~
By performing the heat treatment up to 100 ° C., the amount of water in calcium hydroxide or soda lime can be reduced and the carbon dioxide in calcium hydroxide or soda lime can be efficiently removed or reduced.

Further, in the case of a method of performing only heat treatment in an inert gas atmosphere without cooling calcium hydroxide or soda lime, calcium hydroxide or soda lime is preferable in an inert gas atmosphere such as nitrogen. Is 30
The heat treatment is preferably performed at ˜300 ° C., more preferably 50 to 200 ° C., and particularly preferably 60 to 100 ° C.

As a preferred specific example of the method for purging the above-mentioned calcium hydroxide or soda lime with an inert gas, nitrogen is used as the inert gas, and 1.0 g of calcium hydroxide or soda lime is added to nitrogen. To 0.003 to 0.040 m ³ , more preferably 0.02
0 to 0.040 m ³ , particularly preferably 0.030 to 0.
040 m ^{3 is} to be purged. When the purge amount of the inert gas is small, can not be reduced to carbon dioxide and water content, and also by increasing up to 0.10 m ³ beyond 0.040M ^3, the effect is almost the same.

Further, by removing or reducing carbon dioxide from the gas containing carbon disulfide, calcium hydroxide or soda lime can adsorb carbon disulfide effectively without being inhibited by carbon dioxide, which is preferable.

Thus, in the present invention, the calcium hydroxide or soda lime pretreated by the above method is brought into contact with the gas containing carbon disulfide. The contact is preferably carried out by heating under an inert gas atmosphere because more carbon disulfide can be adsorbed. Nitrogen is preferable as the inert gas, and the heating temperature is 25 to 360 ° C.,
Particularly preferably, it is 270 to 330 ° C. Oxygen liberated from calcium hydroxide or soda lime by such heating contact seems to work effectively for adsorption of carbon disulfide.

Further, in the present invention, carbon disulfide can be more effectively removed by adding at least one component selected from alkali metal compounds to calcium hydroxide or soda lime. Examples of the alkali metal compound include sodium hydroxide, potassium hydroxide, sodium oxide, potassium oxide and the like. Among these, those in which the alkali metal is sodium or potassium are particularly preferable, and they may be added alone, You may add in combination. The amount of addition is 1 to 10 in total with respect to the amount of calcium hydroxide or soda lime.
%, Especially 1-5% by weight is preferred.

The calcium hydroxide or soda lime is preferably crushed or molded into a suitable size because the pressure loss is reduced, and when contacted under heating conditions, it is desirable that the specific surface area be large. Specifically, a particle size of about 2.0 to 10.0 mm (specific surface area of about 2.0 to ²⁰ m ² / g) is used, but its shape, apparent density, etc. may be appropriately selected. Further, the gas containing carbon disulfide to be treated in the present invention is not limited, but the present invention is a gas containing carbon disulfide and is a decomposition component of SF _{6 in} a PFC mixture in a PFC purification step. It can be suitably applied to a gas containing CS ₂ generated by the reaction of s and activated carbon.

[0014]

EXAMPLES Examples of the present invention will be given below together with comparative examples, but the present invention is not limited to the following examples.

Example 1 As a reactor, an inner diameter of 40 mm,
A SUS pipe having a length of 500 mm was installed vertically, and 679 g of soda lime was filled so that the height of the layer was 300 mm. As a pretreatment of the filled soda lime, 0.030 m ^{3 of} nitrogen (N ₂ ) was added to 1.0 g of soda lime.
Purged. Then, a reactor filled with soda lime was charged with 1010 pp of carbon disulfide (CS ₂ ) at a constant concentration.
A mixed gas diluted with N ₂ so as to be introduced at m was introduced by a mass flow controller at a flow rate of 754 cc / min. A sampling port was installed in the outlet side pipe of the reactor from the main exhaust line to collect a sample gas. The sample gas was analyzed by a gas chromatography / mass spectrometer (HP5973 manufactured by HEWLETT PACKARD) (detection limit of analyzer: 3 vol.ppm). Processing capacity of CS ₂ soda lime was a breakthrough upon reaching approximately 5% of CS ₂ concentration of CS ₂ concentration introduced gas in the outlet gas (50 ppm). The results are shown in Table 1 below. That is, the CS ₂ throughput shown in Table 1 is the C in the outlet gas.
The amount of CS ₂ treated by 1 g of the treating agent (soda lime) until the S ₂ concentration exceeds 50 ppm.

[Embodiment 2] The same as the one used in Embodiment 1.
-For soda lime 1.0g as pretreatment of soda lime
Then N₂To 0.005m³Example 1 except for purging
CS under the same conditions as ₂Was tested. Below the result
It is shown in Table 1.

Comparative Example 1 The soda lime used in Example 1 was not pretreated by N ₂ purge,
Other than that, the CS ₂ removal test was conducted under the same conditions as in Example 1. The results are shown in Table 1 below.

[Example 3] When the gas containing CS ₂ was treated in Example 1, except that the center of the packed layer of soda lime used was heated from the outside so that the temperature was 300 ° C.
A CS ₂ removal test was conducted under the same conditions as in Example 1. The results are shown in Table 1 below.

Example 4 Example 1 was repeated except that the soda lime used in Example 1 was calcium hydroxide.
A CS ₂ abatement test was conducted under the same conditions as described above. The results are shown in Table 1 below.

[0020]

[Table 1]

[Examples 5 to 7] As a pretreatment of the soda lime used in Example 1, the center of the packed bed was 80 ° C (Example 5), 100 ° C (Example 6) in an N ₂ atmosphere, A CS ₂ abatement test was conducted under the same conditions as in Example 1, except that the temperature was externally heated to 300 ° C. (Example 7) for 2 hours and then cooled to 25 ° C. The results are shown in Table 2 below.

[Comparative Example 2] As a pretreatment of the soda lime used in Example 1, heating was performed from the outside for 2 hours so that the center of the packed bed was 500 ° C in an N ₂ atmosphere, and then cooled to 25 ° C. A CS ₂ abatement test was conducted under the same conditions as in Example 1 except for the above. The results are shown in Table 2 below.

[Examples 8 and 9] Used in Example 1
As a pre-treatment of the soda lime, after cooling to 0 ℃, N
₂In an atmosphere, the center of the packed bed is 25 ° C. (Example 8), 1
Externally heated to 00 ° C. (Example 9) for 2 hours
And the same conditions as in Example 1 except that it was cooled to 25 ° C.
And CS₂Was tested. The results are shown in Table 2 below.
You

[Examples 10 and 11] The soda lime used in Example 9 was used under the same conditions as in Example 6 (Example 10), except that the soda lime used in Example 6 was calcium hydroxide. A CS ₂ removal test was performed under the same conditions as in Example 9 (Example 11) except that calcium hydroxide was used. The results are shown in Table 2 below.
Shown in.

[0025]

[Table 2]

[Examples 12 and 13] CS _{2 was used under the} same conditions as in Example 1 except that 1.5 to 5.0% by weight of sodium hydroxide and potassium hydroxide were added to the soda lime used in Example 1. Was tested. The results are shown in Table 3 below.

Comparative Example 3 As a pretreatment of the soda lime used in Example 1, heating was performed from the outside for 2 hours in an air atmosphere so that the center of the packed bed was 100 ° C., and then cooled to 25 ° C. A CS ₂ abatement test was conducted under the same conditions as in Example 1 except that the CS ₂ was used. The results are shown in Table 3 below.

Example 14 A CS ₂ removal test was conducted under the same conditions as in Example 12, except that the soda lime used in Example 12 was calcium hydroxide. The results are shown in Table 3 below.

[0029]

[Table 3]

[0030]

According to the method for removing carbon disulfide of the present invention, CS in the components remaining in the rectification column in the PFC refining step is
_2, specifically the CS ₂ in the gas mixture such as a gas containing CS ₂ generated by the reaction between decomposed components of SF ₆ in the PFC mixture and activated carbon, with low energy, can be easily and efficiently removed.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Ando 1-5-13 Nishishinbashi, Minato-ku, Tokyo 8th Toyo Kaikai Building 8F PFC collection and reuse project room (72) Inventor Kenichi Hachitaka Port of Tokyo 1-5-13 Nishi-Shimbashi, Tokyo 8F Toyo Kaiji Building 8F PFC collection / reuse project room (72) Inventor Takeshi Manabe 1-5-13 Nishi-Shimbashi, Minato-ku Tokyo 8F PFC collection / reuse Reuse Project Room (72) Inventor Katsuto Edawa 1-5-13 Nishi-Shimbashi, Minato-ku, Tokyo 8th Toyo Kaiji Building 8F PFC Recovery / Reuse Project Room (72) Inventor Akihiko Nitta Minato-ku, Tokyo Nishishinbashi 1-5-13 No. 8 Toyo Kaiji Building 8F PFC Recovery / Reuse Project Room (72) Inventor Tadashi Goto Sat, 1-5-13 Nishi-Shimbashi, Minato-ku, Tokyo 8th Toyo Kaiji Building 8F PFC recovery / reuse project room (56) Reference JP-A-57-165489 (JP, A) JP-A-62-152519 (JP) , A) JP-A-49-51189 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 53/34

Claims (10)

(57) [Claims] 1. A gas containing carbon disulfide and calcium hydroxide or soda lime are used to reduce the amount of water in calcium hydroxide or soda lime and to remove or reduce carbon dioxide in calcium hydroxide or soda lime. A method for removing carbon disulfide, characterized in that the carbon disulfide is brought into contact with each other in a standing state. 2. The calcium hydroxide or soda lime is subjected to cooling treatment and heat treatment in an inert gas atmosphere to reduce the amount of water in the calcium hydroxide or soda lime and to reduce the water content in the calcium hydroxide or soda lime. The method for removing carbon disulfide according to claim 1, which removes or reduces the carbon dioxide. 3. The cooling treatment of calcium hydroxide or soda lime and the heat treatment in an inert gas atmosphere are carried out by adding calcium hydroxide or soda lime to -30 to 10 ° C.
The method for removing carbon disulfide according to claim 2, which is carried out by heating at 25 to 300 ° C. in an inert gas atmosphere after cooling. 4. By heat-treating calcium hydroxide or soda lime in an inert gas atmosphere,
The method for removing carbon disulfide according to claim 1, wherein the amount of water in calcium hydroxide or soda lime is reduced and carbon dioxide in calcium hydroxide or soda lime is removed or reduced. 5. The heat treatment of calcium hydroxide or soda lime in an inert gas atmosphere is carried out by adding calcium hydroxide or soda lime to 30 to 30 in an inert gas atmosphere.
The method for removing carbon disulfide according to claim 4, which is carried out by heat treatment at 300 ° C. 6. The calcium hydroxide or soda lime is purged with an inert gas to reduce the amount of water in the calcium hydroxide or soda lime and to remove or reduce the carbon dioxide in the calcium hydroxide or soda lime. The method for removing carbon disulfide according to claim 1. 7. An inert gas of 0.003 to 0.040 per 1.0 g of calcium hydroxide or soda lime.
The method for removing carbon disulfide according to claim 6, wherein m ³ purging is performed. 8. A gas containing carbon disulfide and calcium hydroxide or soda lime in an inert gas atmosphere, 2
The method for removing carbon disulfide according to any one of claims 1 to 7, wherein the carbon disulfide is contacted at 5 to 360 ° C. 9. The inert gas is nitrogen, 2 to 8.
5. The method for removing carbon disulfide according to any one of 1. 10. The method for removing carbon disulfide according to claim 1, wherein at least one component selected from alkali metal compounds is added to calcium hydroxide or soda lime.