KR100714031B1 - Exhaust gas purifying catalyst compound, catalyst comprising said compound and method for preparing the compound - Google Patents

Abstract

Provided is a catalyst which does not require activating by firing, which is a barrier to obtaining a catalyst having high activity, and which is sufficiently complexed with V and Mo, and a method for producing the same. Provided is a catalyst that dramatically increases low temperature activity and durability.

Vanadium and molybdenum, the catalyst compound for exhaust gas purification represented by the formula (NH ₄ ) _x Mo ₂ V _x O _{(3x + 6)} having an atomic ratio (V / Mo) of 3/2, wherein x is 2.8 to 3.2, and A method for producing the compound, characterized in that the molybdenum oxide (MoO ₃ ) and ammonium metavanadate [NH ₄ VO ₃ ] is reacted for a predetermined time in the presence of water.

Description

Flue gas purification catalyst compound, catalyst containing the compound, and preparation method thereof {EXHAUST GAS PURIFYING CATALYST COMPOUND, CATALYST COMPRISING SAID COMPOUND AND METHOD FOR PREPARING THE COMPOUND}

The present invention relates to a catalyst for purifying exhaust gas, and more particularly, has excellent low temperature activity and SOx resistance, and is particularly effective in reducing reaction by ammonia (NH ₃ ) of nitrogen oxide (NOx) and oxidative decomposition reaction of dioxins. The present invention relates to a catalyst exhibiting high activity and a method of preparing the same.

NOx contained in flue gas or flue gas discharged from power plants, various factories, automobiles, etc. is a source of photochemical smog and acid rain.As effective removal method of NOx, by selective contact reduction using ammonia (NH ₃ ) as a reducing agent Flue gas or flue gas denitration methods are widely used in thermal power plants. Titanium oxide (TiO ₂ ) based catalysts containing vanadium (V), molybdenum (Mo) or tungsten (W) as active ingredients are used as catalysts used in such flue gas or flue gas denitrification. Vanadium-containing catalysts have not only high activity but also less deterioration due to impurities contained in flue gas, and can be used at lower temperatures, making them the mainstream of current denitrification catalysts (Japanese Patent Application Laid-Open No. 50-128681). Etc). The catalyst is usually molded and used in honey cam shape and plate shape, and various catalyst production methods are invented.

Furthermore, in recent years, since a high toxicity of dioxins is contained in waste combustion flue gas and industrial flue gas, a catalyst for oxidatively decomposing dioxins while denitrification has been invented.

Many of the catalysts described above include (i) a method of kneading the titanium oxide and salts of catalytically active components such as V, Mo, and W with kneading with water, followed by shaping and calcining; (ii) It is customary to form titanium oxide, and to prepare a fired body by impregnating a mixed solution of catalytically active component salts (impregnation method) (Japanese Patent Application Laid-Open No. 50-128681, Japanese Patent Application No. 53). -34195, etc.).

The method for preparing a catalyst by the above-described conventional kneading method and impregnation method is not necessarily the best catalyst manufacturing method in terms of the catalyst's activity, and is not particularly preferable when obtaining a catalyst having high low temperature activity as described above. There were many things that were not.

The problems inherent in these methods can be explained by kneading and impregnation.

1) Kneading method

(1) In order to obtain a highly active catalyst (final product), it is necessary to activate the salts of the added active ingredient contained in the molded catalyst by firing. However, since the active ingredient and titanium oxide contained in the molded catalyst are sintered by firing, it is difficult to obtain a catalyst having high low temperature activity (final product).

(2) Titanium oxide particles, salts of active ingredients such as V, Mo, and W, or oxide particles, become composites only after all of them are mixed and calcined by kneading, so-called composites of V and Mo or W The effect is not enough. The kneading process thus produces a catalyst (final product) with slightly improved durability and low SOx resistance.

2) impregnation method

(1) As with the kneading method, it is necessary to activate the active ingredient by firing the shaped catalyst. Therefore, since the sintering of each active ingredient cannot be avoided, a catalyst having high activity, particularly high temperature activity, cannot be obtained.

② Since the catalyst is formed and calcined in advance to impregnate the active ingredient by impregnation, the compounding of the active ingredient is easier than the kneading method. On the other hand, however, the concentration of the active ingredient differs between the inside and the surface of the catalyst, making it difficult to maintain the ratio between two or more active ingredients in the catalyst within a certain value, and each active ingredient is adsorbed by titanium oxide during impregnation. Because of this, you cannot expect the most appropriate combination effect.

To solve each problem under the background described above,

(A) using an impregnation method and a kneading method such as an impregnation method for impregnating a vanadium salt in a titanium oxide-molybdenum oxide carrier and other impregnation methods for sequentially impregnating a titanium oxide carrier with W, V, and the like; and

(B) Improvement of the impregnation method is attempted.                 

However, these methods do not necessarily achieve sufficient effects.

An object of the present invention is to consider the catalyst which does not need to activate the catalyst component by the impaired firing in the prior art method of obtaining a catalyst with high activity, and also considers a catalyst which generates a complex by complexing vanadium and molybdenum. In addition, the present invention provides a catalyst and a method for producing such a catalyst, and a catalyst having high activity, particularly low temperature activity and greatly increased durability.

The method employed in the present invention to achieve the above object is (i) Molybdenum-Vanadium (Mo-V) composite compound (hereinafter referred to as "composite compound") having a specific composition that does not need to be activated by firing simply referred to as "compound (Sometimes referred to) as an active ingredient, a method of impregnating the compound with a carrier containing titanium oxide as a main component, or (ii) a method of adding a composite compound to titanium oxide particles or powder and then kneading.

Therefore, the present invention is summarized as follows.

(1) The catalyst compound for exhaust gas purification represented by the following rational formula whose atomic ratio (V / Mo) of vanadium and molybdenum is 3/2 or less.

(NH ₄ ) _x Mo ₂ V _x O _{(3x + 6)}

In the above formula, x is 2.8 to 3.2.

(2) A catalyst for purification of exhaust gas, in which a water-soluble compound recited in (1) is supported on a carrier.                 

(3) A catalyst for purification of exhaust gas produced by impregnating a water soluble compound recited in (1) above into a titanium oxide carrier or kneading a titanium oxide powder together with the water soluble compound.

(4) The catalyst for exhaust gas purification according to the above (2) or (3), wherein the catalyst is prepared by calcining the catalyst recited in the above (2) or (3) at a temperature of 500 ° C or lower. .

(5) A method for producing the catalyst compound recited in the above (1), comprising reacting molybdenum oxide (MoO ₃ ) with ammonium metavanadate (NH ₄ VO ₃ ) for a predetermined time in the presence of water.

(6) A composition for exhaust gas purification catalyst containing a water-soluble compound recited in (1) above and a sol-like substance such as silica sol.

(7) A catalyst for purification of exhaust gas in which the composition recited in (6) is supported on a carrier.

(8) after pre-mixing the water-soluble compound recited in (1) with a sol-like substance, such as a silica sol, supporting the mixture of the water-soluble compound and the sol-like substance on a titanium oxide carrier, or oxidizing Method for producing a catalyst for flue gas purification comprising the step of mixing in the titanium powder.

Mo-V catalyst compound used in the present invention was found by the present inventors as a result of earnest research to solve the above-mentioned problems of the prior art, ammonium metavanadate (NH ₄ VO ₃ ) and molybdenum trioxide (MoO ₃ ) Is a reddish brown substance obtained by stirring in water to 3/2 (or 6/4) or close to the atomic ratio V / Mo, and then stirring for a predetermined time (typically 10 hours or more), and the solubility is 170 g / liter at room temperature. As a big thing is characterized. The present inventors have tried to determine the structure of the compound, but in the present step, the V / Mo ratio, which is produced when the ammonium metavanadate and molybdenum trioxide, which are hardly soluble in water, are added to the water and then stirred for a long time, is 3 / It is known only to be 2 or near and high solubility reddish brown compound. And molybdenum trioxide (MoO ₃ ) -5 vanadium oxide (V ₂ O ₅ ), ammonium metavanadate (NH ₄ VO ₃ ) -ammonium molybdate [(NH ₄ ) ₆ ㆍ Mo ₇ O ₂₄ ㆍ 4H ₂ O] Starting material of ammonium paratungstate hexahydrate [(NH ₄ ) ₁₀ H ₁₀ ㆍ W ₁₂ O ₄₆ ㆍ 6H ₂ O] -ammonium metavanadate, or ammonium metavanadate tritungsten oxide (WO ₃ ) Attempts were made to produce compounds similar to the compounds of the present invention, but the compounds with high solubility as described above were not produced from attempts using this combination. Therefore, the term "molybdenum- vanadium (Mo-V) compound" as used herein refers to a stable compound having high reddish brown solubility produced when the ammonium metavanadate and molybdenum oxide are stirred together with water. Since the compound of the present invention has high activity per se, when the compound of the present invention is added to titanium oxide, the mixture does not need to be calcined again to be activated. Furthermore, since molybdenum and vanadium are complexed to form a stable compound in the present invention, the compound of the present invention is hard to be eroded by SOx contained in the exhaust gas and provides a highly durable catalyst.

In the production of the catalyst of the present invention, an operation of impregnating a solution containing the Mo-V compound described above with a pre-prepared titanium oxide carrier at a predetermined concentration is employed. Since the Mo-V compound exhibits high activity even immediately after drying, activation of the compound by firing is not necessary, but a firing step may be added if necessary.

The catalyst using the Mo-V compound of the present invention can be obtained not only by the above impregnation method but also by a method of forming and drying the Mo-V compound after addition to the titanium oxide powder, and firing as necessary.

Furthermore, since the Mo-V compound used in the catalyst of the present invention is extremely stable, it does not decompose even when mixed with a sol state such as a silica sol, and thus active by supporting the mixed solution of the Mo-V compound and the sol state in a titanium oxide carrier. And a catalyst having high strength can be obtained.

As described above, the essence of the present invention is the use of a novel Mo-V-containing composition discovered by the inventors of the present invention, and therefore, inorganic fibers, other catalyst components, inorganic or organic binders, and the like are added to the catalyst or titanium oxide. The scope of the present invention is not limited by the fact that it contains. Moreover, when the activation by the calcination of the molded catalyst is not performed, a catalyst having the highest activity and the longest durability is obtained. Depending on the strength of the catalyst and the use conditions, the catalyst may be calcined at 500 ° C or lower. Furthermore, the amount of Mo-V compound impregnated or added to titanium oxide is not limited, but is generally good when selected to be 20% or less of titanium oxide (based on weight. Equal to or less), preferably 10% or less. Easy to get.

[Action]                 

In order to explain the operation and effect of the present invention, the problems of the catalyst obtained by the conventional kneading method and the impregnation method will be described first. Fig. 2 (A) schematically shows the cross section of the surface layer before firing of the catalyst obtained by the conventional kneading method. As can be seen from the figure, the added active ingredients V (vanadium) compound (1) and Mo (molybdenum) compound (2) are each compound particles in the drying process, the particles of each compound and titanium oxide particles ( 3) exist in a mixed state. In order for the catalyst in this state to show activity, the active component needs to be calcined to become an oxide. Furthermore, in order to compound the V compound particles and the Mo compound particles in the separated part to exhibit a complex effect such as improvement in durability, it is necessary to fire at a higher temperature and thermally diffuse and react with each other. Therefore, the sintering of not only the active ingredient but also titanium oxide proceeds, resulting in a catalyst having a low specific surface area and high activity cannot be expected. In addition, complexation by thermal diffusion may not be sufficient in terms of durability since not all active ingredients react uniformly.

2B schematically shows a cross section of the surface layer of the catalyst obtained in the drying step of the catalyst by a conventional impregnation method. Also in the case of impregnation method, in the drying step, particles of each active ingredient are separately deposited on the surface of the titanium oxide (TiO ₂ ) particles 3, so that it is necessary to revive by firing or to complex the active ingredients. . Moreover, as a problem peculiar to the conventional impregnation method, the distribution of each active ingredient occurs in the catalyst due to the difference in the affinity (adsorption force) of each component and TiO ₂ in the mixed solution of the impregnated active ingredient. Therefore, it is extremely difficult to maintain a uniform active ingredient ratio throughout the catalyst, and it is also difficult to obtain high durability by complexing the active ingredients.

On the other hand, Figure 1 is a schematic diagram of the cross-sectional surface layer of the catalyst according to the present invention, as can be seen from the figure, the catalyst of the present invention is a solution of the newly found high stability Mo-V compound to the catalyst carrier Since the Mo-V compound is prepared by impregnating the Mo-V compound on a carrier, the active ingredient Mo and V are already present on the surface of the titanium oxide particles 3 at the end of the catalyst drying process as the particles 4 in a complexed state. There is no need to compound the active ingredients again. Moreover, the catalyst of the present invention does not require activation by firing because the Mo-V compound itself supported on the carrier has high activity. Therefore, for the catalyst of the present invention, a sintering step for sintering the active ingredient and titanium oxide is not necessary, and thus a catalyst having a high activity, in particular a high surface area and extremely low temperature activity can be obtained. If the calcination step is employed in the catalyst production method of the present invention for reasons other than activation and complexation, the calcination can be sufficiently performed at the lowest temperature necessary for the purpose and the catalyst with high activity can be easily obtained. Furthermore, it should be noted that the added active ingredient maintains a certain ratio of Mo / V in any of the catalysts of the present invention, and thus does not require a special complex treatment and always obtains an active and durable catalyst. It becomes possible.

A further advantage of the present invention is that the newly discovered Mo-V compound is extremely stable, does not destroy even when mixed with silica sol or TiO _2, and can be impregnated with a mixed solution with silica sol or kneaded with TiO _2. Is the point. In this way, it is possible to impregnate or knead the colloidal silica and the active ingredient having a large effect of improving the bulk at once, thus simplifying the production process of the catalyst.

In addition, since the Mo-V compound used in the present invention has little affinity with TiO ₂ , the Mo-V compound is uniformly supported up to the inside of the catalyst. In low temperature denitrification around 200 ° C used for waste gas such as waste incineration flue gas, all of the active sites of the catalyst are used. At low temperatures, deterioration due to SOx tends to be remarkable, but since the supported Mo-V compound does not react with SOx stably and easily, a catalyst having high SOx resistance, which was not conceivable in the past, can be obtained. It becomes possible.

Furthermore, the catalyst of the present invention exhibits high performance even in oxidative decomposition of organic chlorine compounds, and denitrification and dioxins of waste incineration flue gases, which need to have both durability and oxidation activity of chlorine-containing chlorine compounds such as dioxins at around 200 ° C. It is also most suitable as a flow removal catalyst.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram of the surface layer cross section of the catalyst which shows the distribution state of the active component of the catalyst by this invention.

FIG. 2 is a schematic diagram similar to that of FIG. 1 showing a distribution state of an active ingredient of a catalyst according to the prior art. FIG.                 

3 is a graph comparing the performance of the catalyst in the Examples and Comparative Examples of the present invention.

* Explanation of symbols for the main parts of the drawings

1: V compound 2: Mo compound 3: titanium oxide

4: Mo-V compound of the present invention

Hereinafter, the present invention will be described in detail with specific examples. However, the scope of the present invention is not limited by these examples.

Example 1

A slurry containing 40.6 g of molybdenum trioxide (MoO ₃ ) and 49.4 g of ammonium metavanadate (NH ₄ VO ₃ ) added to 410 g of water was stirred gently at room temperature for 20 hours to react with each other to completely dissolve in water. It was. In the obtained solution, the concentration of the Mo-V compound was about 18 wt.%, The V / Mo atomic ratio of the compound was 3/2, and the formula of the reddish brown substance produced and dissolved in water was (NH ₄ ) ₃ Mo ₂ It can be represented by V ₃ O ₁₅ .

Comparative Example 1

To a slurry of 49.8 g of ammonium molybdate [(NH ₄ ) ₆ .Mo ₇ O ₂₄ .4H ₂ O] and 49.4 g of ammonium metavanadate (NH ₄ VO ₃ ) was added to 410 g of water at room temperature for 20 hours. Stir gently. In this case, the solid content concentration in the slurry at the end of the stirring was about 18 wt.%, And the V / Mo atomic ratio in the slurry was 3/2, which is the same as that of Example 1, but ammonium metavanadate is water. It did not melt | dissolve in, and the reddish brown product was not obtained.

Comparative Example 2

A slurry containing 49.8 g of ammonium molybdate [(NH ₄ ) ₆ .Mo ₇ O ₂₄ .4H ₂ O] and 38.4 g of vanadium pentoxide (V ₂ O ₅ ) was added to 410 g of water at room temperature for 20 hours. Stirred. In this case, the solid concentration in the slurry at the end of stirring was about 18 wt.%, And the V / Mo atomic ratio in the slurry was 3/2, which is the same as in Example 1, but vanadium pentoxide was dissolved in water. It did not dissolve and no reddish brown product was obtained.

Comparative Example 3

To 410 g of water, a slurry containing 65.4 g of tungsten trioxide (WO ₃ ) and 49.4 g of ammonium metavanadate (NH ₄ VO ₃ ) was gently stirred at room temperature for 20 hours to completely dissolve these compounds by reacting with each other. It was. The V / Mo atomic ratio in the slurry was 3/2, which was the same as in Example 1, but neither of the two compounds added was dissolved in water, resulting in no reddish brown product.

As can be seen from the results of Example 1 and Comparative Examples 1 to 3, the reddish brown material produced in Example 1, having a V / Mo atomic ratio of 3/2 and high solubility in water, was prepared from ammonium metavanadate in water. It is considered to be a specific compound produced by reacting molybdenum trioxide. Therefore, it was found that these specific compounds were not produced when the starting materials were different, and that even though an oxide of tungsten (W) cognate with the molybdenum (Mo) compound was used instead of the molybdenum compound, it was found that no specific compound was produced.

Example 2

Slurry containing 40% titania, 20% silica sol, and 1% polyvinyl alcohol in a network of twisted yarns made of 1400 E glass fibers having a diameter of 9 µm with 10 / inch roughness. Was impregnated and dried at 150 ° C. to obtain a catalyst substrate having rigidity.

On the other hand, 1.5 kg of titanium oxide having a specific surface area of about 230 m ² / g and 75 g of oxalic acid were added to form a paste, followed by addition of 300 g of silica and alumina fibers to make it uniform. Kneaded until a paste.

The obtained paste was inserted between the two catalyst substrate sheets prepared above and passed through a rolling roller to form a 0.7 mm thick titania-containing sheet. This was dried at room temperature and calcined at 400 ° C. for 2 hours to obtain a titania carrier.

This titania carrier was immersed in the Mo-V compound solution synthesized in Example 1 to support the Mo-V compound, and dried at 80 ° C for 2 hours. The MoO ₃ and V ₂ O ₅ contents in the obtained catalyst were 4.8 wt.% And 4.5 wt.% With respect to TiO ₂ , respectively.

Comparative Example 4

Slurry containing 40% titania, 20% silica sol, and 1% polyvinyl alcohol in a network of twisted yarns made of 1400 E glass fibers having a diameter of 9 µm with 10 / inch roughness. Was impregnated and dried at 150 ° C. to obtain a catalyst substrate having rigidity.

On the other hand, a paste of 88.3 g of ammonium molybdate and 75 g of oxalic acid was added to the mixture of 1.5 kg of titanium oxide with a specific surface area of about 230 m ² / g and 86.7 g of ammonium metavanadate to paste It was made into a phase and kneaded until 300 g of silica alumina fibers were further added until it became a uniform paste.

The obtained paste was inserted between the two catalyst substrate sheets prepared above, and the sheet having a thickness of 0.7 mm was formed by passing through a rolling roller. This was dried at room temperature and then dried at 80 ° C. for 2 hours to obtain a catalyst body.

The MoO ₃ and V ₂ O ₅ contents in the obtained catalyst body were 4.8 wt% and 4.5 wt.%, Respectively, relative to TiO ₂ .

Examples 3-6

The catalyst obtained in Example 2 was calcined at 200, 300, 400 and 500 ° C. for 2 hours to obtain a catalyst.

Comparative Examples 5 to 8

The catalyst obtained in Example 4 was calcined at 200, 300, 400 and 500 ° C. in the same manner as in Examples 3 to 6 to obtain a catalyst.

Comparative Examples 9 and 10

8.67 g of ammonium metavanadate and 8.83 g of ammonium molybdate were dissolved in 41 cm ³ of an aqueous 10% monomethyl amine solution. The obtained solution was dipped and impregnated with the same titania carrier as used in Example 2, dried at room temperature first, and then dried at 80 ° C to obtain a catalyst of Comparative Example 9.

This catalyst was calcined again at 500 ° C. for 2 hours to obtain a catalyst of Comparative Example 10.

Each catalyst of Examples 2-6 and Comparative Examples 4-10 was cut | disconnected into the strip of 20 mm x 100 mm, and the denitrification test was done on condition of Table 1. The obtained results are shown in FIG. 3 in relation to the firing temperature of the catalyst and the denitrification rate. And the drying temperature is also part of the calcination temperature, and the catalyst data when only the drying treatment is included in FIG. 3.

As can be seen from FIG. 3, the catalyst of the present invention exhibits extremely high activity. Moreover, the catalyst of the comparative example does not obtain high activity unless it is calcined at 400 ° C or higher, whereas the catalyst of the present invention obtains the same excellent performance as that of the calcined catalyst even in the catalyst of Example 2, which is not calcined at all. lost. From this fact, it is clear that the catalyst of the present invention does not need to be subjected to an activating process such as firing, and therefore, it can be seen that there is an extremely large effect in terms of activity and production cost.

TABLE 1

 Temperature (℃)      200  Area speed (m / h)       17 Gas composition NO NH ₃ O ₂ CO ₂ H ₂ O  200 240 10 6 6

On the other hand, Examples 2 and 6 and Comparative Examples 4, 8, 9, and to each of the catalyst 10 at 200 ℃ while the SO ₂ 200 ppm comprising a flue-gas exposure 100 hours irradiation the catalyst deactivation is also caused by SO ₂ It was. That is, the performance of the catalyst at 200 ° C before and after exposing the gas to the SO ₂ -containing gas was measured under the conditions shown in Table 1, and the obtained results are shown in Table 2.

TABLE 2

 catalyst  Initial denitrification performance (%) Denitrification rate after SO ₂ treatment (%) Example 2 92 85 Example 6 89 80 Comparative Example 4 27 5 Comparative Example 8 71 20 Comparative Example 9 21 2 Comparative Example 10 56 14

As is apparent from Table 2, the catalysts of the comparative example significantly decreased in activity as all of the catalysts of the comparative example were exposed to the SO ₂ -containing gas, whereas the catalysts of the examples had very little deactivation. In particular, it can be seen that the catalyst of Example 2 has the least activity deterioration compared to other catalysts. This is considered to be because the catalysts of the examples are not easily influenced by SOx in addition to sufficient compounding of molybdenum and vanadium by supporting the compounds in the form of Mo-V compounds in the catalyst.

As described above, in the present invention, it was found that not only a highly active catalyst is obtained without firing according to the present invention, but also the catalyst of the present invention is extremely excellent in terms of durability.

Hereinafter, other embodiments are shown in order to explain the effects of the present invention in more detail.

Example 7

A catalyst was prepared in the same manner as in Comparative Example 4 except that a solution of the Mo-V compound prepared in Example 1 was used instead of the solution of ammonium molybdate and ammonium metavanadate in Comparative Example 4.

Example 8

To a solution of the Mo-V compound prepared in Example 1 was added 500 g of colloidal silica containing 20 wt.% SiO ₂ (manufactured by Nippon Chemical Co., Ltd., silica sol-o) to obtain a mixed solution of these two components. . Using this solution, a catalyst was prepared in the same manner as in Example 2.

Comparative Example 11

To a monomethyl amine aqueous solution containing a mixture of ammonium metavanadate and ammonium molybdate used in Comparative Example 9, 50 g of colloidal silica (manufactured by Nippon Chemical Co., Ltd., Japan) was added to prepare a solution. Using the solution, a catalyst was prepared in the same manner as in Comparative Example 9.

Example 9

The denitrification activity at 200 ° C. was measured using the catalyst obtained in Example 4, and 10 ppm of chlorobenzene was added as a dioxin simulant in the exhaust gas to measure the oxidation rate of chlorobenzene by the catalyst.                 

The results of the performance test of the catalyst obtained in Example 7 as in Example 2 are shown in Table 3 together with the results of Example 2. From Table 3, it can be seen that high performance is obtained similarly to the impregnation method even when the Mo-V compound is used as the catalyst raw material of the kneading method as shown in Example 7.

TABLE 3

   catalyst  Mo-V compound addition method  Denitrification Rate (%)   Example 2     Impregnation method    92   Example 7     Kneading method    91

Furthermore, the activity and bending strength test results at 200 ° C. of the two catalysts obtained in Example 8 and Comparative Example 11 are shown in Table 4, respectively. From Table 4, the catalyst of Comparative Example 11 is not only low in activity, but also has a very low bending strength as compared to the catalyst of Example 8. This is presumably because the silica sol and the vanadium salt were changed into a gel material by mixing the aqueous solution of the mixture of the Mo salt and the V salt with the silica sol and were not impregnated into the titania carrier. As can be seen from this example, the Mo-V compound of the present invention can be arbitrarily mixed with a silica sol, so that the strength enhancer and the active ingredient can be simultaneously supported, and a high strength and high activity catalyst can be obtained by simple operation. Can be.

TABLE 4

 catalyst   Denitrification Rate (%) Bending strength (kg / cm ² )  Example 8     72      140  Comparative Example 11     14       60

As a result of the test conducted in Example 9, it was found that the catalyst of the present invention obtained a high value of 80% or more as the oxidation decomposition activity of chlorobenzene. As described above, the catalyst of the present invention not only has excellent low temperature activity at 200 ° C., but also is difficult to deteriorate by SOx contained in waste incineration flue gas, and also has excellent oxidation activity of chlorine-containing organic compounds containing dioxins. . In recent years, simultaneous disposal of dioxin decomposition and denitrification is desired in an increasing number of waste incinerators, etc., but the catalyst of the present invention is an extremely excellent catalyst that meets such social needs.

According to the present invention, a catalyst compound having catalytic activity can be obtained without requiring an activation step by firing. The catalyst which contains this compound on the support or knead | mixed and contains is excellent in low temperature activity, durability, and dioxins decomposition activity, and high efficiency of a waste incinerator purification apparatus etc. is attained. In addition, since the firing as the activating process is not necessary, not only the manufacturing process can be simplified, but also the catalyst design focused on the catalytic activity can be made, and various improvements can be made in terms of performance and economy.

Furthermore, the Mo-V compound used in the present invention is not only stable when mixed with a sol state substance such as silica sol, but also does not cause gelation of the sol. Therefore, the active ingredient can be simultaneously supported in the silica sol impregnation step of the catalyst which is performed for the purpose of improving the strength, and the catalyst of high strength and high activity can be obtained in a simple step.

Claims (8)

A catalyst compound for purification of exhaust gas represented by the following trial formula, wherein the atomic ratio (V / Mo) of vanadium and molybdenum is 1.4 to 1.6. (NH ₄ ) _x Mo ₂ V _x O _{(3x + 6)} In the above formula, x is 2.8 to 3.2. A catalyst for purifying exhaust gases, characterized in that the catalyst compound for purifying exhaust gases defined in claim 1 is supported on a carrier. A catalyst for purification of exhaust gas, which is prepared by impregnating the catalyst for purification of exhaust gas as defined in claim 1 in a titanium oxide carrier or kneading titanium oxide powder together with the catalyst for purification of exhaust gas. The catalyst for purification of exhaust gas according to claim 2 or 3, wherein the catalyst is further calcined at a temperature of 500 ° C or lower. A method for purifying exhaust gas according to claim 1, comprising reacting molybdenum oxide (MoO ₃ ) and ammonium metavanadate (NH ₄ VO ₃ ) in the presence of water until these two compounds are completely dissolved in water. Process for preparing a catalyst compound. An exhaust gas purification catalyst composition comprising the catalyst compound for exhaust gas purification defined in claim 1 and a substance in a sol state. A catalyst for purifying exhaust gases in which the composition defined in claim 6 is supported on a carrier. After mixing the exhaust gas purification catalyst compound defined in claim 1 and the sol state material in advance, and then supporting the mixture of the exhaust gas purification catalyst compound and the sol state on a titanium oxide carrier, or mixed in the titanium oxide powder Method for producing a catalyst for purification of exhaust gas comprising the step of doing.

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