JP2000051694A - Catalyst for decomposing carbonyl sulfide and/or hydrogen cyanide and decomposition method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the high conversion ratio of COS and HCN when mixed gas containing COS or HCN is decomposed and to suppress the deterioration of decomposition activity in a steam atmosphere. SOLUTION: When mixed gas containing COS or HCN is decomposed, a catalyst containing alumina, a group VI metal and barium is used. In this catalyst, the high decomposition activity of COS can be obtained by supporting alumina and the high decomposition activity of HCN can be obtained by supporting the group VI metal. Further, the conversion of alumina to boehmite in a steam atmosphere and the deterioration of decomposition activity are suppressed by supporting barium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to carbonyl sulfide (COS), for example, a gas obtained by partially oxidizing heavy oil or coal, an exhaust gas from a coke oven, or an exhaust gas from a pyrolysis process of heavy oil.
COS is converted to CO ₂ and H ₂ S, and HCN is converted to CO and NH ₃ or CH ₄ and NH ₃ by decomposing a mixed gas containing hydrogen and hydrogen cyanide (HCN).
The present invention relates to a catalyst used for the decomposition and a decomposition method for removing the same.

[0002]

2. Description of the Related Art Gasified gas produced from a partial oxidation gasification furnace of heavy oil or coal includes, for example, hydrogen sulfide (H ₂ S) and C
Impurities such as OS and HCN are contained, and a steam having a partial pressure of several atmospheres coexists. One of the methods for removing H ₂ S is methyldiethanolamine (MDE).
A wet absorption method using A) is known.
_Since it selectively removes 2S, the removal rate of COS is low, and HCN forms a strong compound with MDEA, deteriorating MDEA.
And HCN conversion processing.

In this pretreatment, COS is converted into H ₂ S which can be easily treated with MDEA by HCN by a hydrolysis reaction represented by the following formulas (1) and (2) or a hydrogenation reaction represented by the following formula (3). Is NH that does not adversely affect MDEA solution processing
_This is the process performed to convert to ₃ . At the same time, the reaction of the formula (4) proceeds as a side reaction at the same time, and the progress of the side reaction promotes the by-product of COS and becomes a factor of lowering the COS removal rate.

COS + H ₂ O → CO ₂ + H ₂ S (1) HCN + H ₂ O → NH ₃ + CO (2) HCN + 3H ₂ → NH ₃ + CH ₄ (3) CO + H ₂ S → COS + H ₂ ... (4) Normally, alumina-based catalyst is used for COS conversion,
With this activated alumina catalyst, the side reaction progresses slowly, and COS
Is known to be effective for the hydrolysis of Examples of the activated alumina catalyst include alkalized alumina supporting a potassium salt reported in Japanese Patent Publication No. 5-70500 and Japanese Patent Publication No. 7-68528, and alumina and barium reported in Japanese Patent Publication No. 5-4133. An oxide or the like is used.

[0005]

However, although the alkalized alumina catalyst has a high COS decomposition performance,
Even in the presence of steam of only about 0.3 atm, the catalyst base
It has been empirically recognized that the formation of mitigation proceeds and the decomposition performance is significantly deteriorated. These also include HC
There is almost no N conversion activity.

On the other hand, the catalyst comprising alumina and barium oxide has a large COS decomposition activity at a low temperature and suppresses the formation of boehmite in a steam atmosphere. Excellent activity, but still HC
It has been found that the activity on N decomposition is extremely low.

The present invention has been made under such circumstances, and an object of the present invention is to remove COS and / or HCN from a mixed gas containing COS and / or HCN when decomposing and removing COS and / or HCN. It is an object of the present invention to provide a COS and / or HCN decomposing catalyst and a decomposing method which can decompose at a large conversion rate and can suppress the deterioration of the decomposing activity under a steam atmosphere.

[0008]

Therefore, the catalyst for decomposing carbonyl sulfide and / or hydrogen cyanide of the present invention contains alumina, a Group VI metal and barium, and a mixed gas containing carbonyl sulfide and / or hydrogen cyanide and steam. By contacting in the presence, carbonyl sulfide and / or hydrogen cyanide in the mixed gas is decomposed. Here, the catalyst desirably uses molybdenum and / or chromium as the group VI metal. Further, it is preferable to contain 0.5 to 20% by weight of an oxide of a Group VI metal with respect to the alumina.
Desirably, it contains from 3% to 10% by weight of barium oxide.

In the method for decomposing carbonyl sulfide and / or hydrogen cyanide of the present invention, a mixed gas containing carbonyl sulfide and / or hydrogen cyanide is brought into contact with a catalyst containing alumina, a Group VI metal and barium in the presence of steam. Thereby, carbonyl sulfide and / or hydrogen cyanide in the mixed gas is decomposed. Here, the mixed gas may be brought into contact with a plurality of catalysts containing alumina, a Group VI metal, and barium.

The present invention is characterized in that a catalyst containing alumina, a Group VI metal and barium is used as a catalyst for decomposing carbonyl sulfide and / or hydrogen cyanide. And a high activity in the decomposition of hydrogen cyanide by the group VI metal. Further, the progress of boehmite conversion of alumina under a steam atmosphere is suppressed by barium, so that the degradation of decomposition activity under a steam atmosphere can be suppressed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to COS, HCN, H ₂ S, such as a gas obtained by partially oxidizing heavy oil or coal, a coke oven exhaust gas, and an exhaust gas from a heavy oil pyrolysis process. An example in which the present invention is applied to a method for removing these impurities from a mixed gas containing such impurities will be described. In this example, the method of the present invention is a step prior to the wet absorption step of removing H ₂ S,
It is applied to the decomposition process of OS and HCN. In this decomposition process, a mixed gas containing COS and HCN (hereinafter, “mixed gas”)
) Is brought into contact with the catalyst in the presence of steam to convert and remove COS and HCN.

First, an example of a decomposition apparatus in which the method of the present invention is performed will be described with reference to FIG. In the figure, reference numeral 11 denotes a reaction vessel, and at the top and bottom of the reaction vessel 11, a gas supply pipe 12 and a gas discharge pipe 13 provided with valves V1 and V2, respectively.
And are connected respectively. A catalyst bed 14 filled with a catalyst, which will be described later, is provided inside the reaction vessel 11, and the catalyst bed 14 is supported from both upper and lower sides by catalyst supports 15, 16. The catalyst support 15,1
6, a large number of gas flow holes 15a and 16a each having a size that allows the mixed gas to flow therethrough but does not allow the catalyst to pass through are formed.

Next, the catalyst of the present invention will be described. The catalyst of the present invention contains alumina, a Group VI metal, and barium. Such a catalyst is produced, for example, as follows. First, the formed alumina is impregnated with an aqueous solution of a barium compound, dried at a temperature of 110 ° C. to 130 ° C., and then calcined at a temperature equal to or higher than the decomposition temperature of the barium salt to obtain a carrier composed of alumina and barium.

Here, various compounds such as barium nitrate, barium hydroxide and barium acetate can be used as the barium compound. For example, when barium nitrate is used, the sintering temperature is 600 ° C. to 800 ° C. Is preferably set in the range. As the alumina, various types of alumina can be used, and it is preferable to use γ-type or η-type.

Further, barium in the carrier is considered to constitute a composite oxide with alumina, and the content of barium as an oxide is preferably in the range of 0.3 to 10% by weight based on alumina. This is because if the content of barium oxide is less than 0.3%, a composite oxide with alumina is not sufficiently produced, and even if the content exceeds 10% by weight, unnecessary barium oxide other than the composite oxide increases. This is because the effect of containing a large amount of barium does not occur.

Subsequently, the carrier comprising alumina and barium thus obtained is impregnated with an aqueous solution of a Group VI metal compound as a metal component.
Dry at a temperature of 130-130 ° C, and then 400-600 ° C
Calcination is performed at a temperature of to obtain a catalyst. As the metal component, various Group VI metals can be used, and a plurality of Group VI metals can be combined, but it is particularly preferable to use molybdenum or chromium. In such a carrier, the Group VI metal is contained in the form of an oxide, but the content of the Group VI metal oxide is preferably in the range of 0.5 to 20% by weight based on alumina based on the experimental results described later.

The shape of the catalyst may be any shape such as a sphere, tablet, Raschig ring, column, or honeycomb, but the equivalent diameter (length of 6 times the ratio of geometric volume to surface area) is 6 mm or less. preferable.

Next, the method of the present invention carried out by the above-described decomposition apparatus will be described. COS of 10 to 1000 ppm by volume or 50 to 500 ppm by volume is usually contained in various mixed gases such as the gas obtained by partially oxidizing the heavy oil and coal, the exhaust gas from the coke oven and the exhaust gas from the pyrolysis process of the heavy oil. HCN is included. In the decomposition method of the present invention, these mixed gases are formed, for example, at a reaction temperature of 110 to 250 ° C. and a normal pressure of 80 K
g / cm ² G under a reaction pressure of 900 to 20,000 h ⁻¹
Gas superficial velocity (gas superficial velocity (gas flow rate) in standard state (0 ° C., 1 atm) per hour with respect to catalyst volume)
To cause the decomposition reaction of COS and HCN to proceed.

That is, the valves V1 and V2 are opened,
Through the gas supply pipe 12, for example, a mixed gas and steam having a ratio of steam / mixed gas of 0.05 to 0.3 are introduced into the reaction vessel 11. In the reaction vessel 11, the mixed gas and steam flow through the catalyst bed 14 through the through holes 15a of the catalyst support 15, come into contact with the catalyst, and a hydrolysis reaction is performed. The reaction proceeds under the reaction conditions. Here, the ratio of the water vapor and the mixed gas requires the presence of water in a stoichiometric amount or more necessary for the hydrolysis reaction, and it is desirable that the composition of the water is not more than the dew point composition.

Thus, in the reaction vessel 11, the above-mentioned (1)
The hydrolysis of COS and HCN shown in the formulas (2) and (2) or the hydrogenation reaction shown in the formula (3) is carried out, and COS becomes C
HCN is converted to O ₂ and H ₂ S, and HCN is converted to NH ₃ and CO or NH ₃ and CH ₄ for removal. And CO
S concentration is about 10 ppm by volume, HCN concentration is 3 ppm by volume
The mixed gas from which COS and HCN have been removed up to about m is discharged to the outside of the reaction vessel 11 through the gas discharge pipe 12,
Thereafter, in the next wet absorption process, a process of removing H ₂ S by, for example, MDEA is performed.

As described above, the catalyst of the present invention comprises alumina and VI
Since it is characterized by containing a group metal and barium, not only COS but also HC
The decomposition of N can proceed efficiently, and the degradation of decomposition activity in a steam atmosphere can be suppressed. Therefore, the catalyst of the present invention is useful as a catalyst for decomposing and removing COS and HCN in a partially oxidized gas of coal or heavy oil, which is carried out particularly under a high steam partial pressure.

That is, the alumina catalyst is selectively active in the COS decomposition reaction due to the slow progress of the by-product reaction of COS shown in the above formula (4). Can increase the activity of the HCN decomposition reaction. In addition, by supporting barium, the COS by-product reaction is suppressed, and
It is possible to suppress a decrease in the decomposition activity under a steam atmosphere.

[0023]

EXAMPLES Next, experimental examples performed to confirm the effects of the catalyst of the present invention will be described.

Comparative Example 1 Molded Alumina Support 100
g was placed in a 500 cc beaker and 47 cc of a 0.42 mol / l barium nitrate solution was added dropwise thereto at room temperature while shaking the alumina carrier to impregnate the alumina carrier with the barium nitrate solution. After that, it is dried in a drier by a conventional method, and calcined in an air stream at 700 ° C. for 5 hours in an electric furnace.
Catalyst X having a barium oxide (BaO) content of 3% by weight with respect to alumina was obtained. As the alumina carrier, γ-
It is an alumina tablet having a shape of 3 mm in diameter and 3 mm in height, a surface area of 160 m ² / g, and a water absorption of 0.1 mm.
The one of 47 cc / g was used.

Comparative Example 2 50 g of a molded alumina carrier
Was placed in a 500 cc beaker, and while shaking the alumina carrier, 37.5 cc of a 0.04 mol / l ammonium molybdate solution was added dropwise at room temperature to impregnate the alumina carrier with the ammonium molybdate solution. Thereafter, the resultant was dried in a drier in a conventional manner, and calcined in an electric furnace at 500 ° C. for 5 hours in an air stream to obtain a catalyst Y having a molybdenum oxide (MoO ₃ ) content of 3% by weight based on alumina. As the alumina carrier, γ-alumina having a cylindrical shape with a diameter of 1.6 mm and a height of 5 mm, a surface area of 190 m ² / g, and a water absorption of 0.75 cc / g was used.

Example 1 50 g of catalyst X obtained in Comparative Example 1
Was placed in a 500 cc beaker, and while dropping the catalyst X, 23.5 cc of a 0.06 mol / l ammonium molybdate solution was added dropwise thereto at room temperature to impregnate the catalyst X with the ammonium molybdate solution. Thereafter, it is dried in a drier by a conventional method, and is then dried in an electric furnace at 500 ° C. in an air stream for 5 hours.
After calcining for hours, Catalyst A having a MoO ₃ content of 3% by weight and a BaO content of 3% by weight based on alumina was obtained.

Example 2 The concentration of ammonium molybdate in Example 1 was changed so that
A catalyst B having an O ₃ content of 5% by weight and a BaO content of 3% by weight and a catalyst C having an MoO ₃ content of 10% by weight and a BaO content of 3% by weight based on alumina were obtained.

Example 3 50 g of catalyst X obtained in Comparative Example 1
Was placed in a 500 cc beaker, and while the catalyst X was being mixed down, a 0.84 mol / l chromium nitrate solution was added thereto.
5 cc was added dropwise at room temperature, and the catalyst X was impregnated with a chromium nitrate solution. Thereafter, the resultant was dried in a drier by a conventional method, and fired in an electric furnace at 500 ° C. for 5 hours in an air stream. Next, the same operation was repeated twice to obtain chromium oxide (Cr
Catalyst D having a ₂ O ₃ ) content of 9% by weight and a BaO content of 3% by weight was obtained.

Example 4 A series of operations of impregnation, drying and firing in Example 3 was performed only once, and the content of Cr ₂ O ₃ was 3% by weight and the content of BaO was 3% by weight based on alumina. Catalyst E was obtained.

[Example 5] Molded alumina carrier 100
g was placed in a 500 cc beaker, and 76 cc of a 0.26 mol / l barium nitrate solution was added dropwise at room temperature while the alumina carrier was being mixed down, so that the alumina carrier was impregnated with the barium nitrate solution. Thereafter, the resultant was dried in a drier by a conventional method, and calcined in an electric furnace at 700 ° C. for 5 hours in an air stream to obtain a catalyst carrier. Here, as the alumina carrier, γ-
Alumina having a columnar shape with a diameter of 1.6 mm and a height of 5 mm, a surface area of 190 m ² / g, and a water absorption of 0.1 mm.
The one with 75 cc / g was used. 0.04 mol / l ammonium molybdate solution 3 was added to 50 g of the catalyst carrier.
7.5 cc was added dropwise at room temperature, and the catalyst support was impregnated with an ammonium molybdate solution. Thereafter, it is dried in a drier in a conventional manner, and calcined in an electric furnace at 500 ° C. for 5 hours in an air stream, so that the MoO ₃ content with respect to the alumina is 3% by weight,
Catalyst F having an aO content of 3% was obtained.

[Experimental Example 1] First, in order to confirm the effect of adding a Group VI metal such as molybdenum or chromium to a carrier made of alumina and barium on the decomposition of COS and HCN, catalysts A, D and catalysts were used. X COS and HC
The decomposition activity of N was measured using a high-pressure fixed-bed flow reactor similar to the device shown in FIG. The source gas composition is H ₂ :
40% by volume, CO: 40% by volume, H ₂ S: 1% by volume, C
OS: 500 ppm by volume, HCN: 100 ppm by volume,
H ₂ O: 10% by volume and N ₂ : 9% by volume. The reaction was carried out at a gas superficial velocity of 5000 h ^-1 , a pressure of 36 Kg / cm ² G, and an inlet gas temperature of 180 ° C., and the decomposition activity of COS and HCN was examined by measuring the conversion of these.
Here, the COS conversion rate indicates that the higher the conversion rate, the more efficiently the decomposition proceeds and the higher the decomposition activity.

FIG. 2 shows the results. Catalysts A, D,
The COS conversion of X was 99.6%, 99.3%, and 9 respectively.
9.4%, indicating that these catalysts show almost the same high activity on COS decomposition. Thus, it is understood that the COS decomposition proceeds efficiently by the combination of alumina and barium regardless of the presence or absence of the Group VI metal.

On the other hand, the conversion rate of HCN decomposition was 30.0% for catalyst X containing no group VI metal, whereas catalyst A containing molybdenum and catalyst D containing chromium were each 99.9%.
%, 90.0%. From this, it is recognized that the addition of molybdenum or chromium to a catalyst containing alumina and barium significantly improves HCN decomposition activity, and it is understood that Group VI metals exhibit high activity in HCN decomposition.

EXPERIMENTAL EXAMPLE 2 In order to confirm the effect of the concentration of the Group VI metal carried on the decomposition activity of COS and HCN, COS and HCN in Catalyst A, Catalyst B, Catalyst C and Catalyst D, and Catalyst E were examined. Was measured in the same manner as in Experimental Example 1.

The results are shown in FIG. First, MoO ₃
Regarding the relationship between the supported concentration of COS and the decomposition activity of COS and HCN, the COS conversion was 9% for catalysts A, B and C, respectively.
9.3%, 94.5% and 71.3%,
It was recognized that the lower the MoO ₃ carrying concentration, the higher the COS decomposition activity. On the other hand, the conversion rates of HCN decomposition were 99.9%, 99.9% and 9% for catalysts A, B and C, respectively.
Since it was 8.4%, the HCN decomposition activity was MoO ₃
It was recognized that there was almost no change in the loading concentration range of 3 to 10%.

Also, Cr_TwoO_ThreeLoading concentration and COS and HC
Regarding the relationship between the decomposition activity of N, the COS conversion
99.4% and 99.5% for D and E, respectively, and C
r_TwoO _ThreeRecognized to be almost the same regardless of loading concentration
And the presence of chromium increases the COS decomposition activity by alumina.
It was understood that it had no effect. On the other hand, HCN conversion rate
90.0% and 66.2% for catalysts D and E, respectively.
, Cr_TwoO_ThreeHCN decomposition activity increases as the loading concentration increases
It was found to improve.

From these experimental results, it was found that COS and HCN
The decomposition activity of HCN decreases as the concentration of MoO ₃ supported decreases, and HCN decreases.
Since it was recognized that the decomposition activity tended to increase as the concentration of Cr ₂ O ₃ supported increased, the inventors further determined that M
Catalysts were prepared with varying concentrations of oO ₃ and Cr ₂ O ₃ , and the conversions of COS and HCN were measured in the same manner as in Experimental Example 1.

First, regarding the MoO ₃ carrying concentration, although the HCN conversion rate is improved by the addition of molybdenum,
Since S conversion which decreases with too many support concentration, considered optimal MoO ₃ supported concentration to enhance the COS and HCN conversion rate exists, BaO support concentration for the alumina and 3%, MoO ₃ The loading concentration is 0.
Catalysts with 3% by weight, 0.5% by weight, 20% by weight, and 25% by weight were manufactured to optimize the concentration of MoO ₃ supported.

FIG. 4 shows the COS and HCN conversion rates of these catalysts, respectively. From this result, it was confirmed that the conversion rates of COS and HCN were both high when the MoO ₃ supporting concentration was 0.5% by weight, but the conversion rate of HCN was rapidly lowered when the concentration became 0.3% by weight. When the MoO ₃ carrying concentration is 20
It was found that the conversion of HCN did not change significantly when the content was more than 10% by weight, but the conversion of COS dropped sharply.

On the other hand, for the catalyst containing alumina, barium and chromium, the concentration of BaO
%, And a catalyst having a Cr ₂ O ₃ carrying concentration of 0.3% by weight, 0.5% by weight, 20% by weight, and 25% by weight.
The r ₂ O ₃ carrying concentration was optimized.

The conversion rates of COS and HCN of these catalysts are also shown in FIG. From this result, the conversion of HCN of the catalyst containing alumina, barium, and chromium was Cr ₂
Even when the O ₃ carrying concentration is 20% by weight or more, both are high,
When it is less than 0.5% by weight, it becomes low, and 0.3% by weight
Rapidly it is recognized that to decrease becomes on, and Cr ₂ O
₃ It was recognized that the conversion rates of COS and HCN were almost the same even when the supported concentration exceeded 20%.

From these results, in order to obtain high decomposition activity for both COS and HCN, it is necessary to use V such as molybdenum or chromium.
The concentration of the group I metal supported is 0.5% by weight or more based on alumina.
It is considered preferable to be in the range of 20% by weight.

[Usage Example 3] Next, in order to confirm the influence of barium on the COS decomposition activity, CO of catalyst F and catalyst Y was
The S conversion was measured in the same manner as in Experimental Example 1. However, the measurement was performed with the gas superficial velocity in the range of 3000 to 20000 h ^-1 .

The results are shown in FIG. 5, where the horizontal axis shows the contact time between the catalyst and the mixed gas, and the vertical axis shows the COS residual rate. Here, the contact time is 1 / superficial velocity (GHSV (G
as Hourly Space Velocity) [h ^-1 ]), and the COS residual rate is higher as the residual rate is higher.
This indicates that the activity of OS degradation is low. In the figure, □ indicates catalyst F, and △ indicates catalyst Y.

FIG. 5 shows that the catalyst Y containing no barium has a lower COS residual ratio with an increase in the contact time up to a contact time of 2 × 10 ^-4 hours, but after that the COS residual ratio increases again. , The COS decomposition activity was found to be low. This is considered to be because the COS by-product reaction represented by the above formula (4) proceeds when the contact time becomes longer to some extent.

On the other hand, in the case of the catalyst F containing barium, the COS residual ratio decreased with an increase in the contact time, and the contact time was 2.6 ×
It was found that it became almost constant after more than 10 ^-4 hours. From these results, it is understood that by supporting barium, the by-product reaction of COS is suppressed, and the COS decomposition reaction can be selectively advanced. The reason for this is not clear, but the coexistence of barium
It is considered that the chemical / electronic state change of the group VI metal, which is presumed to be the active site of the by-product reaction, occurs.

Experimental Example 4 To confirm the effect of barium on the amount of boehmite produced, the catalysts A, D and Y were replaced with H ₂ O at 15% by volume and H ₂ at 85% by volume. The treatment was performed in a steam atmosphere containing the mixture. The steam treatment is performed using a high-pressure fixed-bed flow reactor similar to the apparatus shown in FIG.
Gas superficial velocity 5000 h ^-1 , pressure 27 kg / cm ² G,
The test was performed at an inlet gas temperature of 220 ° C. After the treatment, each catalyst was subjected to X-ray diffraction to measure the peak area of boehmite.

The results are shown in FIG. 6, where the horizontal axis represents the processing time and the vertical axis represents the peak area of boehmite. In the figure, ■ indicates catalyst A, △ indicates catalyst D, and ○ indicates catalyst Y. From the results, it was recognized that the peak area of boehmite increased with the treatment time in the case of the catalyst Y containing no barium, whereas the peak area of the boehmite in the catalysts A and D containing barium was confirmed. It was found that the surface area did not increase with the treatment time.
From this fact, by supporting barium, steel is
It can be understood that boehmite conversion of alumina under a steam atmosphere is suppressed, and deterioration of COS decomposition activity under a steam atmosphere due to boehmite conversion of alumina is suppressed.

In the above, the catalyst of the present invention may contain a plurality of Group VI metals. Further, in the present invention, the decomposition reaction may be carried out by bringing the mixed gas into contact with a catalyst containing alumina, a Group VI metal, and barium and having different types, combinations and compositions of metal components. For example, as shown in FIG. 7, a plurality of catalyst beds are provided in a reaction vessel 11, a first catalyst bed 21 is filled with a catalyst containing alumina, molybdenum and barium, and a second catalyst bed 22 is made of alumina and chromium. And a catalyst containing barium and the mixed gas may be sequentially contacted with the first and second catalyst beds 21 and 22 to perform the decomposition reaction.

Further, among the catalysts containing alumina, Group VI metal and barium, catalysts having different types, combinations and compositions of metal components may be filled in the same catalyst bed, or types and combinations of metal components may be packed. Alternatively, catalyst beds having different compositions may be separately provided in a plurality of reaction vessels, and these reaction vessels may be connected to each other, and a mixed gas may be sequentially supplied to these reaction vessels to be brought into contact with each catalyst bed.

The present invention may be applied to the decomposition of a mixed gas containing only COS or the decomposition of a mixed gas containing only HCN.
In addition, the mixed gas containing COS and HCN is decomposed to form COS
May be applied to remove only COS and H
It may be applied to the case where only the HCN is removed by decomposing a mixed gas containing CN.

[0052]

As described above, according to the present invention, since a catalyst containing alumina, a Group VI metal and barium is used as a catalyst for decomposing a mixed gas containing COS and / or HCN, COS and / or HCN are used. Can be advanced at a high conversion rate, and COS can be used even in a steam atmosphere.
And / or deterioration of HCN decomposition activity can be suppressed.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing an example of a disassembly apparatus for carrying out the method of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a catalyst and conversion rates of COS and HCN.

FIG. 3 is a characteristic diagram showing a relationship between a catalyst and conversion rates of COS and HCN.

FIG. 4 is a characteristic diagram showing a relationship between a catalyst and conversion rates of COS and HCN.

FIG. 5 is a characteristic diagram showing a relationship between a contact time between a catalyst and a mixed gas and a COS residual ratio.

FIG. 6 is a characteristic diagram showing a relationship between a peak area of boehmite and a processing time.

FIG. 7 is a vertical sectional side view showing an example of a disassembling apparatus for carrying out the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Reaction container 12 Gas supply pipe 13 Gas exhaust pipe 14 Catalyst bed 15, 16 Catalyst support 21 First catalyst bed 22 Second catalyst bed

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[Procedure amendment]

[Submission date] December 2, 1998 (1998.12.
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0045

[Correction method] Change

[Correction contents]

FIG. 5 shows that the catalyst Y containing no barium has a lower COS residual ratio with an increase in the contact time until the contact time reaches 2 × 10 ⁴ hours, but after that, the COS residual ratio increases again. It was recognized that the COS decomposition activity was low. This is considered to be because the COS by-product reaction represented by the above formula (4) proceeds when the contact time becomes longer to some extent.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0046

[Correction method] Change

[Correction contents]

On the other hand, in the case of the catalyst F containing barium, the COS residual ratio decreased with an increase in the contact time, and the contact time was 2.6 ×
Be substantially constant was found more than 10 ^four hours. From these results, it is understood that by supporting barium, the by-product reaction of COS is suppressed, and the COS decomposition reaction can be selectively advanced. The reason for this is not clear, but the coexistence of barium
It is considered that a chemical / electronic state change of the group VI metal which is presumed to be an active site of a by-product reaction occurs.

[Procedure amendment 3]

[Document name to be amended] Drawing

[Correction target item name] Fig. 5

[Correction method] Change

[Correction contents]

FIG. 5

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Sanae Okamoto 2-110 Sunosaki-machi, Handa-shi, Aichi Prefecture JGC Corporation Kinuura Research Laboratory Co., Ltd. (72) Inventor Kozo Imura 2-110 Sunosaki-machi, Handa-shi, Aichi Prefecture JGC (72) Inventor Hideyuki Matsumoto 2-3-1 Minatomirai, Nishi-ku, Yokohama, Kanagawa Prefecture JGC Corporation (72) Inventor Jun Abe 2-3-1 Minatomirai, Nishi-ku, Yokohama-shi, Kanagawa Prefecture JGC Corporation F Term (reference) 4D048 AA04 AA10 AB03 AB05 BA03X BA15X BA25X BA26X BA42X BB01 CA04 CC32 CC46 CC49 4G069 AA03 AA08 BA01A BA01B BB06A BB06B BC13A BC13B BC57A BC58A BC58B BC59A BC59B CA02 CA10 EC01 DA05 DA02

Claims (6)

[Claims] 1. Decomposition of carbonyl sulfide and / or hydrogen cyanide in said mixed gas by contacting with a mixed gas containing alumina, Group VI metal and barium in the presence of steam containing carbonyl sulfide and / or hydrogen cyanide. A catalyst for decomposing carbonyl sulfide and / or hydrogen cyanide. 2. The catalyst for decomposing carbonyl sulfide and / or hydrogen cyanide according to claim 1, wherein the Group VI metal is molybdenum and / or chromium. 3. The catalyst for decomposing carbonyl sulfide and / or hydrogen cyanide according to claim 1 or 2, comprising 0.5 to 20% by weight of an oxide of a Group VI metal based on alumina. 4. A catalyst for decomposing carbonyl sulfide and / or hydrogen cyanide according to claim 1, which contains 0.3 to 10% by weight of barium oxide based on alumina. 5. A gas mixture comprising carbonyl sulfide and / or hydrogen cyanide is brought into contact with a catalyst comprising alumina, a Group VI metal and barium in the presence of steam,
A method for decomposing carbonyl sulfide and / or hydrogen cyanide, comprising decomposing carbonyl sulfide and / or hydrogen cyanide in the mixed gas. 6. The carbonyl sulfide and / or hydrogen cyanide according to claim 5, wherein the mixed gas containing carbonyl sulfide and / or hydrogen cyanide is brought into contact with a plurality of catalysts containing alumina, a Group VI metal and barium. Disassembly method.