JPH1133353A - Process for removing hydrogen sulfide by using active carbon fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove effectively hydrogen sulfide from gas containing hydrogen sulfide or gas containing oxygen and hydrogen sulfide. SOLUTION: Active carbon fibers are used as an adsorbent, and gas containing hydrogen sulfide is brought into contact with the active carbon fibers in a process for removing hydrogen sulfide contained in hydrogen sulfide containing gas. As the active carbon fibers, PAN active carbon fibers or pitch active carbon fibers are used preferably, and the temperature at the time of contact operation is 70-180 deg.C preferably. In the case oxygen is also contained in the hydrogen sulfide gas, the effectiveness is more remarkable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing hydrogen sulfide from a gas containing hydrogen sulfide or a gas containing oxygen and hydrogen sulfide, and more specifically, to a method for removing hydrogen sulfide using activated carbon fibers as an adsorbent. To a method for removing hydrogen sulfide.

[0002]

2. Description of the Related Art Hydrogen sulfide is regulated as an air polluting odorant, but hydrogen sulfide is generated in geothermal power generation, oil refining, natural gas refining, rayon production, sewage treatment, sludge treatment, garbage disposal, and the like. Conventionally, as a technique for removing hydrogen sulfide, there has been known a method for removing hydrogen sulfide by first bringing a hydrogen sulfide-containing gas into contact with and adsorbing activated carbon at normal temperature.

The above method is carried out, for example, as shown in FIG. 1 (a). However, in this method, the amount of hydrogen sulfide adsorbed by activated carbon is small, and frequent regeneration or replacement of activated carbon is required. Japanese Patent Application Laid-Open No. Hei 8-281113 discloses an improved adsorption amount of trimethylamine, hydrogen sulfide, methyl mercaptan, and the like. It is stated that an element and / or a compound thereof, and a halogen or a halogen compound are added, whereby excellent deodorizing performance can be exhibited in a practical environment.

There is also known a method in which a part of hydrogen sulfide in a hydrogen sulfide-containing gas is converted into sulfur dioxide by partial combustion, and then converted to sulfur at a high temperature using a catalyst and recovered. This method is carried out, for example, in the mode as shown in FIG. 1 (b). In this method, sulfur dioxide is produced by partial combustion of hydrogen sulfide, and is subsequently converted into hydrogen sulfide by the conversion catalyst and the sulfur of the produced sulfur dioxide. This method has a problem that a large-scale apparatus such as conversion of hydrogen is required, and it is difficult to remove hydrogen sulfide particularly when the concentration of hydrogen sulfide in the gas is low.

In addition, for example, Japanese Patent Application Laid-Open No. 8-299420
In the item, activated carbon not only adsorbs deodorizing components, but also adsorbs bacteria, molds, bacteria, or protozoa that are harmful to the human body, which multiplies and returns to the environment where deodorization is required and contaminates. In order to solve this problem, at least one antibacterial agent selected from the group consisting of zinc metal and zinc oxide is deposited and adhered to the inner and outer surfaces of the activated carbon by an electrolytic method. However, this technique is specifically used for acetaldehyde (Example 1), river water (Example 3), or air purification (Example 4), and activated carbon is used as a hydrogen sulfide adsorption and removal agent. Do not use.

[0006]

SUMMARY OF THE INVENTION The present inventor has paid special attention to activated carbon fibers as an adsorbent for hydrogen sulfide gas, and the activated carbon fibers have excellent hydrogen sulfide adsorbing ability. In spite of this, it has been found that it has excellent hydrogen sulfide adsorption ability. Based on this finding, the present invention provides a method for removing hydrogen sulfide in a hydrogen sulfide-containing gas, which comprises contacting a gas containing hydrogen sulfide or a gas containing oxygen and hydrogen sulfide with an activated carbon fiber adsorbent. The purpose is to provide.

[0007]

According to the present invention, hydrogen sulfide is used, wherein activated carbon fiber is used as an adsorbent and a gas containing hydrogen sulfide or a gas containing oxygen and hydrogen sulfide is brought into contact with the activated carbon fiber. This is a method for removing hydrogen sulfide from contained gas.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, activated carbon fibers are used as an adsorbent for hydrogen sulfide in a gas. Activated carbon fiber (Active Carbon Fiber: hereinafter referred to as “ACF” as appropriate) is also referred to as carbon fiber, and is formed by spinning organic fiber such as rayon or polyacrylonitrile, or coal tar pitch or refined petroleum pitch. It is produced by heat-treating the produced fiber in an inert gas and carbonizing. In the present invention, any of these activated carbon fibers is used, but more preferably PAN-based activated carbon fiber (activated carbon fiber using polyacrylonitrile as a raw material for production) or pitch-based activated carbon fiber (coal tar pitch or petroleum pitch) Activated carbon fiber using a fiber produced by spinning the same as a production raw material) is used.

In the present invention, the operating temperature during the contact is preferably in the range of 70 to 180 ° C., particularly preferably 100 to 180 ° C.
It is carried out in the range of １５０150 ° C. In addition, as described above, hydrogen sulfide is regulated as an air pollutant odor substance. However, according to the present invention, hydrogen sulfide is generated during geothermal power generation, petroleum refining, natural gas refining, rayon production, sewage treatment, sludge treatment, waste disposal, and the like. Hydrogen sulfide can be removed very effectively.

In the present invention, (1) a gas containing hydrogen sulfide or (2) a gas containing oxygen and hydrogen sulfide is brought into contact with activated carbon fiber (ACF), and these gases include other gases. It does not matter. FIG. 2 shows an example of an embodiment of an apparatus for implementing the present invention. In FIG. 2, 1
Is a hydrogen sulfide-containing gas inlet tube, 2 is an ACF packed bed (reaction tube), and 3 is a treated gas outlet tube. Hydrogen sulfide in the hydrogen sulfide-containing gas introduced from the introduction pipe 1 is adsorbed and removed by the activated carbon fiber packed bed 2 or decomposed and adsorbed and discharged from the extraction pipe 3.

[0011]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but it is needless to say that the present invention is not limited by these Examples. The hydrogen sulfide removal activity by ACF in the following was measured by a break-through test.
-Test). An apparatus as shown in FIG. 2 was used. Fill the reaction tube 2 with ACF,
Is introducing-circulating a predetermined concentration of H ₂ S (concentrations = C ₀₎ from the hydrogen sulfide-containing gas inlet tube 1, H ₂ S (concentration = C) the GC chromatography FPD (flame photometric in the gas at the outlet of the reaction tube 2 (Gas chromatography with a detector).

The relative concentration (%) of hydrogen sulfide was calculated by the following equation (1) based on the concentration of H ₂ S at the inlet and outlet of the reaction tube 2 (C ₀ , C: see FIG. 2). In addition, the whole (1
The value obtained by subtracting the value of the relative concentration of hydrogen sulfide (%) calculated from the following formula (1) from the ratio (00%) corresponds to the capture rate (conversion rate) of H ₂ S by the ACF.

[0013]

[Equation 1]

Table 1 shows properties of the various ACFs used in this embodiment. In Table 1, Examples 1 to 4 are PAN-based activated carbon fibers (fiber diameter: 10 to 15 μm).
9 is a pitch-based activated carbon fiber (fiber diameter: 10 to 15 μm)
m). As shown in Table 1, Examples 1 to 4 which are PAN-based
ET surface area is relatively small as 150 to 880 m ² / g,
The carbon content is also about 70%. Nitrogen content is 3-12
%, But the ratio is higher than that of the pitch type. On the other hand, Example 5 which is a pitch-based activated carbon fiber
9 has a high carbon content of about 90%, but has a nitrogen content of 0.3 to 0.7%. The BET surface area of the pitch-based activated carbon fiber is larger than that of the PAN-based activated carbon fiber. In Example 9, it corresponds to about 5 times less than that of Example 2.

[0015]

[Table 1]

<< Example 1: In a nitrogen atmosphere >> FIG.
Using the AN and pitch-based variety ACF is a breakthrough curve when adsorbed H ₂ S. Set ventilation temperature is 30 ℃, A
CF amount 0.3g, nitrogen atmosphere (N ₂ carrier)
In which the concentration of H ₂ S is 100 ppm and the gas flow rate is 100 m
L / min. As shown in FIG. 3, in Examples 5 to 9, which are pitch-based ACFs, all broke within 10 minutes, and the H ₂ S capturing ability was extremely low. On the other hand, PAN
In the system ACF, the H ₂ S trapping ability is remarkably excellent.
H ₂ S could be completely captured for a period of time, 4 hours in Example 3 and 6 hours in Example 2.

In FIG. 3, Example 4 (800 ° C.) and Example 4 (6
00 ° C.) and Example 2 (600 ° C.)
The ACF of Example 4 which is a PAN system was heated at 800 ° C. and 6
It is the data about what baked at 00 degreeC, and also baked at 600 degreeC of the ACF of Example 2 which is also a PAN system. FIG.
Of As, when firing the PAN-based ACF, both H ₂ S trapping ability decreases, the time until breakthrough start indicating that made 2 hours 20 minutes shorter. This is presumably because the firing of the ACF eliminates or almost eliminates the oxygen functional groups on the fiber surface, and does not capture H ₂ S earlier than in the case where the firing is not performed.

Example 2 Temperature Dependence Test in a Nitrogen Atmosphere FIG. 4 shows Example 2 which has the best H ₂ S capturing ability among Examples 1 to 9 when the aeration temperature was changed. It is a test result. Set ventilation temperatures are 30 ° C and 5 ° C, respectively.
0 ° C, 70 ° C, 100 ° C, 200 ° C, ACF
The amount was 0.2 g, the H ₂ S concentration was 100 ppm in a nitrogen atmosphere (N ₂ carrier), and the flow rate was 100 mL / m 2.
in. As shown in FIG. 4, as the aeration temperature was increased, the adsorption holding time was prolonged. At 100 ° C., H ₂ S was adsorbed best, and breakthrough occurred in 3 hours and 25 minutes. However, 20
At 0 ° C., on the contrary, it broke through the earliest in less than 2 hours. These facts show that an excellent hydrogen sulfide removing effect can be obtained when the operating temperature is in the range of about 70 to 180 ° C.

Example 3 In a Nitrogen Atmosphere FIG. 5 shows H ₂ S
₂₀₀ pp in nitrogen atmosphere (N ₂ carrier)
m and the breakthrough curve when the conditions were the same as in Example 2 except that Example 2 was used (flow rate: 200 mL / mi).
n, ACF amount: 0.2 g). As shown in FIG. 5, when the ventilation temperature was 30 ° C., the breakthrough occurred in 1 hour, and when the ventilation temperature was 100 ° C., the breakthrough occurred in 1 hour and 35 minutes.

As described above, according to the facts of Examples 1 to 3, regarding the breakthrough characteristics in nitrogen gas (gas containing no oxygen), PAN-based ACF has higher hydrogen sulfide removal activity,
Although pitch-based ACF is low, when compared, although the two have substantially the same specific surface area, the ability to capture the breakthrough characteristics is greatly different. It is recognized that they are greatly involved. In particular, P
In the case of AN-based ACF, it is considered that a large nitrogen content may contribute to the activity.

Example 4: Capture test in the presence of oxygen FIG. 6
Is the result of H ₂ S capture test in air for Example 2 is a PAN type ACF. When using Example 2,
H ₂ S can be completely captured up to 7 hours at an aeration temperature of 30 ° C. and up to 16 hours at 100 ° C., and the H ₂ S capturing ability is 3.5 in comparison with the case where the atmosphere is only nitrogen.
And 4.6 times. Thus, according to the present invention, it is clear that the presence of oxygen provides a better effect of improving the H ₂ S adsorption ability.

Example 5: Capture test in the presence of oxygen FIG. 7
9 shows the results of an H ₂ S capture test in the air for pitch-based ACFs (Examples 5 to 9). As shown in FIG. 7, for all the ACFs of Examples 6 to 9, breakthrough occurs immediately after the start of aeration at an aeration temperature of 100 ° C., but thereafter shows a steady capture activity. Table 2 shows the steady-state activity as a conversion (%). As shown in Table 2, the activation order was Example 5, Example 6, Example 7, Example 8, and Example 9, and the conversion rates (= capture rates) were 90%, 88%, 87%, and 76, respectively.
%, 69%. For comparison, the activity of an infusibilized system that had not been activated was also evaluated, and it was confirmed that there was almost no activity against H ₂ S (see FIG. 7).

[0023]

[Table 2]

According to the above Examples 4 and 5, in the reaction in the presence of oxygen, in the case of the PAN-based ACF, the capture time is increased by 4 to 5 times, and the improvement of the activity by oxygen is exhibited.
On the other hand, in the pitch-based ACF, breakthrough occurs immediately after the start of ventilation, but after that, high steady-state trapping is observed, such as about 90% in Example 5 and 69% in Example 9, and has excellent H ₂ S removal ability. I understand. In this respect, the details of the action are unclear. However, from such a high steady-state trapping ability, it is presumed that H ₂ S is probably oxidized due to the presence of oxygen, and sulfur is trapped on the surface of the ACF. You.

[0025]

According to the present invention, geothermal power generation, oil refining,
Hydrogen sulfide can be removed very effectively from gas containing hydrogen sulfide generated during natural gas purification, rayon production, sewage treatment, sludge treatment, waste disposal, and the like. It is more effective when the gas containing hydrogen sulfide contains oxygen.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an apparatus in a conventional hydrogen sulfide removal technique.

FIG. 2 is a diagram showing an example of an embodiment of an apparatus for implementing the present invention.

FIG. 3 shows H using various PAN-based and pitch-based ACFs.
_The figure which shows the breakthrough curve of ₂ S adsorption (in nitrogen atmosphere).

FIG. 4 is a diagram showing the results of a capture test of a PAN-based ACF (Example 2) when the ventilation temperature in a nitrogen atmosphere was changed.

FIG. 5 is a view showing a breakthrough curve when a PAN-based ACF (Example 2) is used and the conditions in FIG. 4 are changed.

FIG. 6 is a graph showing the results of a H ₂ S trap test in air for a PAN-based ACF (Example 2).

FIG. 7 is a diagram showing the results of a H ₂ S capture test in air for pitch-based ACFs (Examples 5 to 9).

[Explanation of symbols]

 1 gas introduction pipe containing hydrogen sulfide 2 packed bed of activated carbon fiber (reaction tube) 3 treated gas outlet pipe

Claims (4)

[Claims] 1. A method for removing hydrogen sulfide in a hydrogen sulfide-containing gas, comprising using activated carbon fiber as an adsorbent and contacting the activated carbon fiber with a gas containing hydrogen sulfide. 2. The method according to claim 1, wherein the gas containing hydrogen sulfide is a gas containing oxygen and hydrogen sulfide. 3. The method according to claim 1, wherein the activated carbon fiber adsorbent is a PAN-based activated carbon fiber or a pitch-based activated carbon fiber. 4. The method for removing hydrogen sulfide from a hydrogen sulfide-containing gas according to claim 1, wherein the operating temperature during the contact is 70 to 180 ° C.