JPH1033947A - Removal of nitrogen oxide in exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve denitration efficiency by producing a catalyst carrier by firing ZSM-5 type zeolite as a main raw material and forming the resultant material into a honeycomb structure, depositing cobalt or copper on the catalyst carrier, and using aqueous ammonia, urea containing ammonia, etc., as a reducing agent. SOLUTION: In a removing method of nitrogen oxide in an exhaust gas by contact reaction of a denitration agent obtaining by depositing an activated metal on a catalyst carrier with a NOx-conrtaining gas in the presence of a reducing agent, ZSM-5 type zeolite as a main raw material is fired and formed into a honeycomb structure to give a catalyst carrier and then cobalt or copper as a metal catalyst is deposited on the carrier by an ion-exchange method. At that time, as the reducing agent, aqueous ammonia and urea containing ammonia are used. Moreover, as an ion-exchange method for cobalt Co ion, zeolite is immersed in a solution of acetic acid salt, nitric acid salt containing Co ion and stirred for several hours at 60 deg.C solution temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a method for purifying by removing the nitrogen oxides contained in the exhaust gas of an internal combustion engine or the like (NO _X).

[0002]

Conventionally the NO _X processing techniques are required in various fields, NO _X present in the exhaust gas, for example a diesel engine or the like is harmful to the human body, acid rain when it is dissipated into the air Therefore, it is desired to effectively remove NO _X in these exhaust gases.

[0003] Generally, the above-mentioned NO _X treatment method is put to practical use as a flue gas denitration technique. This flue gas denitrification technique is roughly classified into a dry method and a wet method. At present, a selective catalytic reduction method, which is one of the dry methods, is technically advanced, and is attracting attention as an effective denitration method.

The main reaction of the above selective catalytic reduction method is as follows.

4NO + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O (1) In this reaction, ammonia, hydrocarbon, and carbon monoxide are used as a reducing agent. since oxygen is removed selectively NO _X even coexist, it is effectively used to remove of the NO _X contained in the exhaust gas such as a diesel engine. This reaction uses titanium oxide (Ti
A catalyst containing an oxide such as vanadium (V), molybdenum (Mo), tungsten (W) or a double salt with O ₂ ) as a main component is used. Among them, V ₂ O ₅ / TiO ₂
Based catalysts are effective in terms of activity, selectivity and durability,
It has been operating for more than two years in exhaust gas containing a large amount of SO _X dust as well as O _X.

[0006]

SUMMARY OF THE INVENTION It is an object of the aforementioned selective catalytic reduction method is a high denitration ratio can be obtained it is possible to process the NO _X with a simple system, yet the NO _X into harmless N ₂ gas and H ₂ O The decomposition catalyst has the advantage of eliminating the need for waste liquid treatment.
Since a component other than O _X may be deteriorated, there is a problem that it requires catalyst replacement. Particularly expensive noble metal catalysts there are cases that can not be used from an economic point of view, since and virulent in V ₂ O ₅ is soluble in V ₂ O ₅ / TiO ₂ catalyst Among them, the disposal of the catalyst after use May cause environmental pollution unless special treatment is carried out.

In recent years, cogeneration systems have become widespread due to energy savings. In particular, since a gas engine or a diesel engine, which is an internal combustion engine, needs to burn under excess oxygen, an excess of about 13% is contained in exhaust gas. Contains oxygen. Three-way catalyst is an exhaust gas purifying catalyst of a gasoline engine under the influence of such excess oxygen may cause deterioration of the catalyst metal by the oxidation reaction, it is difficult to completely remove the NO _X in the internal combustion engine.

When ammonia is used as a reducing agent, the ammonia is designated as a dangerous substance, and therefore, there is a problem in handling and storage with high-pressure liquefied gas. When a noble metal or transition metal catalyst is used, the specific gravity of these catalysts is large, which is disadvantageous in actual handling.At a high temperature, the sintering of the catalyst component proceeds, but at a low temperature, ammonium becomes a water component. Alternatively, there is a problem in that a salt such as ammonium sulfate is formed on the catalyst surface by reacting with SO _X and the denitration rate is reduced. Therefore, the operating temperature range is currently limited to 320 ° C to 450 ° C.

As another denitration method, a direct decomposition method or a selective reduction denitration method using a hydrocarbon-based reducing agent has been studied.
For example recent years, transition metal Cu-ZSM-5 zeolite Toka perovskite type complex compound or the like, a material obtained by carrying or ion exchange metal such alkaline earth metals as a catalyst, the reaction of reducing the NO _X with a reducing agent to N ₂ However, this reaction has a drawback that its activity greatly changes depending on the temperature, the combination of a catalyst (metal), a reducing agent, and the like, because the reaction mechanism has not been elucidated in detail. Most also highly active Cu-ZSM-5 zeolite may catalyst performance deteriorates with SO _X or O ₂ in the exhaust gas, which is an obstacle in practical use.

There is also a method of using urea instead of dangerous ammonia as a reducing agent, and TiO ₂ and V ₂ are used as catalyst carriers.
O _5, WO _3, but MoO ₃ or the like is used, in particular TiO ₂ catalysts have low reactivity with the SO _X contained in the exhaust gas,
Since it is hardly deteriorated, it is suitable as a catalyst carrier. However, since the V ₂ O ₅ component of TiO ₂ is soluble and toxic, there is a problem in treating the catalyst.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and it is an object of the present invention to select an optimal catalyst carrier and select a metal and a reducing agent to be carried on the catalyst carrier, thereby improving the exhaust gas with a high denitration rate. It is an object of the present invention to provide a method for removing nitrogen oxides therein.

[0012]

SUMMARY OF THE INVENTION The present invention, in order to achieve the above object, contacting reaction of denitrating agent and NO _X containing gas obtained by supporting an active metal on the catalyst support in the presence of a reducing agent According to the method for removing nitrogen oxides in exhaust gas as described above, according to claim 1, calcination and honeycomb forming are performed using ZSM-5 type zeolite as a main raw material to form a catalyst carrier, and the catalyst carrier is provided with a metal catalyst by an ion exchange method. The present invention provides a method for removing nitrogen oxides in exhaust gas using ammonia or urea containing ammonium, ammonium carbonate or melamine as a reducing agent, carrying cobalt or copper as a reducing agent.

[0013] The zeolite before the calcination step is immersed in an acetate or nitrate solution containing cobalt ions or copper ions, and the mixture is stirred for several hours while being heated, thereby performing cobalt or copper ion exchange.

Further, NH ₄ -ZSM-5 zeolite as a main raw material is formed and calcined to obtain H-type H-ZSM-5,
The ion exchange of cobalt or copper is performed with the ion exchange rate of 5 to 30 (%). Light oil is used as the reducing agent, and is added to the denitration agent at a ratio of light oil / NO = 0.5.

According to the method for removing nitrogen oxides in exhaust gas, ZSM-5 zeolite is used as a main raw material and the ion exchange rate of cobalt or copper is 5 to 30.
(%) To make the conventional NaY or NaA
The denitration rate is remarkably improved as compared with the denitration agent using zeolite, and when ammonia water, urea containing ammonia, ammonium carbonate, and melamine are used as the reducing agent using ZSM-5 zeolite, Decomposition characteristics and denitration rates of substances differ depending on the reducing agent, but a high denitration rate of 85 (%) or more can be obtained using any reducing agent. In addition, by performing ion exchange before firing, N2 can be changed depending on the firing temperature.
The H ₄ type zeolite is changed to an N type zeolite to improve the degree of stability.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of the method for removing nitrogen oxides in exhaust gas according to the present invention will be described below. In the present embodiment, nitrogen oxides (NO
_In the reaction for reducing _X ) to nitrogen gas (N ₂ ), a lightweight, inexpensive and toxic zeolite is used as a catalyst carrier.

Generally, zeolite is composed of aluminum and silica, and X (M ²⁺ , M ⁺¹ ) O.Al ₂ O ₃ .ySiO
A crystalline alumina silicate represented by ₂ · zH ₂ O, which is a crystal having fine pores of 3 to 9 °, but by changing the ratio of aluminum to silica, Y type, X type, A type mordenite type , ZSM-5 type and other structures.

Among them, ZSM-5 type zeolite is known as a chemically stable zeolite. In the present example, a method of firing and honeycomb-forming a ZSM-5 type zeolite as a main raw material to obtain a catalyst carrier, and studying a method of supporting a metal catalyst on the catalyst carrier by an ion exchange method was studied.

In the experiment to which this embodiment was applied, NH ₄ -ZSM-5 zeolite (composition: SiO
₂ / Al ₂ O ₃ = 39.5), the above main raw material was formed into a honeycomb shape and fired. Since a high-temperature sintering step at 700 ° C. to 800 ° C. is performed when the main raw material is formed into a honeycomb shape, NH ₄ in the main raw material escapes to become H-type H-ZSM-5. NH ₄ -ZSM-5 → NH ₃ (g) + H-ZSM-5 This H-ZSM-5 can be used as a catalyst with cobalt C as an active metal.
o is carried by an ion exchange method. Ion exchange rate is 5
%, Ie 5% of the amount of H, is replaced by cobalt. Ammonia water and urea containing ammonium, ammonium carbonate, and melamine were used as reducing agents.

The method of ion exchange of cobalt Co is C
The zeolite is immersed in a solution containing o ions, and the solution temperature is 6
Stir at 0 ° C. for several hours. The salts containing Co ions include acetates, nitrates and the like.

The experimental conditions are described below. (1) Reaction temperature: 400 ° C. (2) Sample gas: NO, SO ₂ (concentration 860 pp
m), oxygen (13% concentration), and the remaining nitrogen gas (6.7 l /
min) (3) Reducing agent: ammonia water (NH ₃ ), 860 ppm as NH ₃ gas in sample gas (4) Honeycomb volume: 6.8 × 10 ^-5 (m ³ ) (5) Comparative example: as zeolite raw material NaY type zeolite and NaA type zeolite are used.

Using the denitration agent according to the present embodiment and the comparative example,
The denitration efficiency was determined by the apparatus shown in FIG. In the figure, reference numeral 1 denotes a normal pressure fixed bed type reaction tank, and 2 denotes a gas introduction pipe.
Are filled with denitration agents 3 and 3, and thermocouples 13 and 14 for temperature measurement are provided at the inlet and outlet of the reaction tank 1. The reaction tank 1 is heated and maintained at a predetermined temperature by a heat retaining heater 4, and a preheater 5 is also provided around a gas introduction pipe 2 close to the reaction tank 1.

Reference numeral 6 denotes a tank filled with a reducing agent solution, 7 denotes a pump for feeding the reducing agent into the reaction tank 1, and 8 denotes a nozzle for injecting the reducing agent solution into the reaction tank 1. Further, in order to prepare the sample gas M to be supplied to the gas introduction pipe 2,
A NO gas cylinder 9, an N ₂ gas cylinder 10, an SO ₂ gas cylinder 11, and an O ₂ gas cylinder 12 are prepared, and a mixed gas thereof is prepared, and the sample gas M flows into the gas introduction pipe 2 via a flow control valve (not shown). You.

At the time of the experiment, the temperature in the reaction tank 1 was maintained at 400 ° C. by the heat retaining heater 4 and the sample gas M was preheated by the preheater 5 to 6.7 (l / min).
At the same time, the pump 7 was started, and the ammonia water as a reducing agent filled in the tank 6 was injected into the reaction tank 1 so that the sample gas had a ratio of 860 ppm as NH ₃ gas in the sample gas. . The injection amount was adjusted so that the composition ratio of the reducing agent and NO at the inlet of the reaction tank 1 was 1: 1.

FIG. 2 is a sectional view showing the inside of the reaction tank 1.
A sealing material 1a is disposed on the inner wall surface of a reaction tank 1 made of stainless steel, and honeycomb-shaped denitration agents 3 and 3 are laminated inside the sealing material 1a.

The sample gas M that does not pass a sample gas M having passed through the reaction vessel 1 to reaction vessel 1, i.e. does not show the NO _X concentration and the oxygen concentration of the sample gas M before and after the reaction NO _X · O ₂ Analysis It was measured by a meter or gas chromatography.

The NO _x concentration of the sample gas M before the reaction is defined as C ₀ (ppm), and the NO _x concentration after the reaction is defined as C ₁ (pp
The denitration rate was determined by the following equation as m).

Denitration rate (%) = {C ₀ (ppm) −C ₁ (ppm)} / {C ₀ (ppm)} × 100 (2) Table 1 shows that zeolite raw material was obtained from the above experiment. NaY-type zeolite, NaA-type zeolite and Z according to this embodiment
The graph shows the denitration rate (%) when SM-5 zeolite was used.

[0029]

[Table 1]

From the results shown in Table 1, the NaY type zeolite or N
Denitration rate of 35% and 20% when using aA type zeolite
It can be seen that the denitration rate of 90% when ZSM-5 zeolite was used was remarkably improved as compared with that of Example 1.

Next, NH ₄ -ZSM-5 zeolite as a main raw material is molded and calcined to obtain H-type H-ZSM-5,
Experiments were carried out under the same conditions while supporting cobalt Co as a catalyst while changing the ion exchange rate. Table 2 shows the denitration rate when the ion exchange rate is 0, 5, 10, 30, 100 (%).
(%).

[0032]

[Table 2]

According to Table 2, it was found that the denitration rate was highest when the cobalt Co ion exchange rate was 5% to 10%. However, when the exchange rate of cobalt Co exceeded 30 (%), the denitration rate tended to decrease. This is because the reducing agent, NH ₃ , selectively adsorbs to H ⁺ (proton) in the zeolite. Therefore, as H ⁺ is exchanged for Co ²⁺ , the amount of NO adsorbed on the catalyst surface increases, and NH 3 _It is considered that the adsorption amount of ₃ was decreased. Therefore, the ion exchange rate of cobalt Co is suitably 5 to 30 (%).

Next, C with an ion exchange rate of cobalt of 5% was used.
Using o-ZSM-5 zeolite, ammonia water as a reducing agent, urea containing ammonia, ammonium carbonate,
An experiment was performed under the same conditions using melamine. In the experiment, the amount of NH ₃ contained in each reducing agent was adjusted to 8 in the sample gas.
It was adjusted to 60 ppm. Table 3 shows the results.

[0035]

[Table 3]

Although the decomposition characteristics and the denitration rate of the substance differ depending on the reducing agent, a denitration rate of 85 (%) or more was obtained using any of the reducing agents.

FIG. 3 shows Co-ZSM-5 according to the present embodiment.
NO is adsorbed to a denitration agent using zeolite and Co-NaY zeolite as main raw materials, and the temperature and desorption when the amount of NO discharged by desorbing NO by the temperature-programmed desorption method is detected by a TCD detector is determined. It is a graph which shows the relationship of separation speed. It can be seen that a large amount of NO is adsorbed on the denitration agent using the Co-ZSM-5 zeolite shown in (1), and almost no NO is adsorbed on the Co-NaY zeolite shown in (2).

Next, a method for producing various types of denitration agents employed in this embodiment will be described together with comparative examples.

[Denitration agent 1] A silica / alumina ratio of 23.
The honeycomb catalyst carrier was manufactured by molding and firing using the NH ₄ type ZSM-zeolite powder of No. 3;
The ion exchange of o was performed before the calcination process. The ion exchange can be performed after the calcination, but depending on the calcination temperature, NH ₄ may be used.
Since the zeolite is changed to N-type zeolite and the stability is improved, it is preferable to carry out the calcination before calcination.

The weight of one piece of the obtained honeycomb catalyst carrier was 250 g, and this was mixed with a 0.1 M concentration of Co (CH ₃ C).
OO) was immersed in ₂ · 4H ₂ O aqueous solution 4 l was subjected to ion exchange by stirring at 60 ° C. 12 hours. After the completion of the ion exchange operation, the carrier was washed with 4 liters of pure water and dried at 150 ° C. for 8 hours. After drying, firing was performed at 700 ° C. for 5 hours to obtain a honeycomb-shaped denitration agent.

As a result of elemental analysis of the obtained denitration agent, it was found that 1.0% by weight of Co was contained.

[Denitration Agent 2] The ion exchange time of Co on the same honeycomb catalyst carrier as above was 60 ° C. for 2 hours. Other operations were the same. As a result of elemental analysis of the obtained denitration agent, it was found that Co was contained at 0.1% by weight, and that the amount of ion exchange could be adjusted by the ion exchange time.

[Denitration Agent 3] The ion exchange time of Co on the same honeycomb catalyst carrier as above was set to 60 ° C. for 24 hours. Other operations were the same. As a result of elemental analysis of the obtained denitration agent, 2.0% by weight of Co was contained.

Comparative Example 1 The same honeycomb catalyst carrier as described above was washed with 4 liters of pure water without performing ion exchange, and dried at 150 ° C. for 8 hours. After drying, an H-type zeolite calcined at 700 ° C. for 5 hours was obtained. Using this H-type zeolite, a denitration agent was prepared in the same manner as in Example 1.

Comparative Example 2 The same honeycomb catalyst carrier as described above was subjected to ion exchange of copper Cu. Specifically, the catalyst support was immersed in 4 liters of a 0.1 M concentration aqueous solution of Cu (CH ₃ COO) ₂ .4H ₂ O and stirred at 60 ° C. for 12 hours to perform ion exchange. After the completion of the ion exchange operation, the carrier was washed with 4 liters of pure water and dried at 150 ° C. for 8 hours. After drying, firing was performed at 700 ° C. for 5 hours to obtain a honeycomb-shaped denitration agent.

As a result of elemental analysis of the obtained denitration agent, it was found that Cu was contained at 0.9% by weight.

[Evaluation of Performance of Denitration Agent] The denitration agent obtained in each of the above Examples and Comparative Examples was filled in the normal-pressure fixed-bed type reaction tank 1 shown in FIG. After pretreatment for one hour, urea was added as a reducing agent at a ratio of NO / urea = 0.5 by flowing a mixed gas shown in Table 4 and denitration was performed at a reaction temperature of 400 to 500 ° C. Table 5 shows the measurement result of the NO purification rate at the time when the state was returned to the steady state.
Shown in

[0048]

[Table 4]

[0049]

[Table 5]

According to Table 5, the NO purification rates of the denitration agents 1 and 2 according to the present embodiment are as good as 93% and 95%, respectively.
By using urea as a reducing agent in a denitration agent containing 0.1 to 1.0% by weight of Co, good denitration characteristics can be obtained, and the NO purification rate of the denitration agent of Comparative Example 1 which does not ion-exchange Co is 30. % Was clearly different. Since the denitration agent 3 contained 2.0% by weight of Co, the NO purification rate was slightly lowered to 85%. The denitration agent ion-exchanged using Cu of Comparative Example 2 has the same NO purification rate as the denitration agent 3 of 85%.
Since somewhat favorable results were obtained, the possibility of practical use of a denitration agent obtained by ion-exchanging Cu like Co was shown.

Next, according to Table 6, the denitration agents obtained in the above Examples and Comparative Example 1 were charged into the reaction tank 1 and pretreated for about 1 hour under the same air flow as described above. The mixed gas shown in Table 4 was circulated and light oil was used as the reducing agent.
Denitration is performed at a reaction temperature of 350 to 450 ° C.
The result of measuring the NO purification rate at 450C and 450C is shown.

[0052]

[Table 6]

According to Table 6, the denitration agents 1 and 2
By using light oil as a reducing agent for each of Examples 2 and 3, good denitration characteristics were obtained under each reaction temperature condition.
NO purification rate of denitration agent without ion exchange
%, 35%. However, since the denitration agent 3 contains 2.0% by weight of Co, the denitration agents 1 and 2
The NO purification rate was slightly lower than that.

Next, in view of the results of Comparative Example 1, the denitration agents 4, 5 obtained by ion-exchanging copper Cu instead of cobalt Co were used.
No. 6 was created.

[Denitration agent 4] The silica / alumina ratio is 23.
A honeycomb catalyst carrier was manufactured by molding and firing using the NH ₄ type ZSM-zeolite powder No. 3 described above. Each of the obtained honeycomb-shaped catalyst supports weighed 250 g, and this was mixed with a 0.1 M aqueous Cu (CH ₃ COO) ₂ .4H ₂ O aqueous solution 4.
The mixture was immersed in a liter and stirred at 60 ° C. for 12 hours to perform ion exchange. After the completion of the ion exchange operation, the carrier was washed with 4 liters of pure water and dried at 150 ° C. for 8 hours. After drying 7
The mixture was fired at 00 ° C. for 5 hours to obtain a honeycomb-shaped denitration agent.

As a result of elemental analysis of the obtained denitration agent, it was found that Cu was contained at 0.9% by weight.

[Denitration agent 5] The ion exchange time of Cu for the same honeycomb catalyst carrier as above was 1.5 times at 60 ° C.
Time and other operations were the same. As a result of elemental analysis of the obtained denitration agent, 0.1% by weight of Cu was contained.

[Denitration agent 6] The ion exchange time of Cu with respect to the same honeycomb catalyst carrier as described above was set to 18 hours at 60 ° C. Other operations were the same. As a result of elemental analysis of the obtained denitration agent, 1.5% by weight of Cu was contained.

Comparative Example 3 The same honeycomb catalyst carrier as above was subjected to Ni ion exchange. Specifically, the catalyst carrier was immersed in 4 liters of a 0.1 M Ni (CH ₃ COO) ₂ .4H ₂ O aqueous solution and stirred at 60 ° C. for 10 hours to perform ion exchange. After the completion of the ion exchange operation, the carrier was washed with 4 liters of pure water and dried at 150 ° C. for 8 hours. After drying, firing was performed at 700 ° C. for 5 hours to obtain a honeycomb-shaped denitration agent.

As a result of elemental analysis of the obtained denitration agent, it was found that Ni was contained at 1.2% by weight. Next, according to Table 7, the denitration agents 4, 5, and 6 obtained in the above Examples and Comparative Example 3 were used.
Is filled in the reaction vessel 1 and subjected to a pretreatment at 400 ° C. for about 1 hour under the same flow of air as described above, and then a gaseous mixture as shown in Table 4 is passed to reduce light oil as light oil / NO = 0.
And denitration was performed at a reaction temperature of 350 to 450 ° C., and the reaction temperature was 350 ° C., 400 ° C.,
The result of measuring the NO purification rate at 450 ° C. is shown.

[0061]

[Table 7]

According to Table 7, the denitration agents 4 and 4
By using light oils as the reducing agents in Nos. 5 and 6, good denitration characteristics were obtained under each reaction temperature condition, and there was a clear difference as compared with the NO removal rates of the denitration agents of Comparative Examples 1 and 3.

In this measurement, the concentration of SO ₂ was set to 0 to 10
Table 8 shows the results of measuring the NO purification rate by changing the concentration to 00 ppm. The continuous aeration time of SO ₂ was 500 hours.

[0064]

[Table 8]

According to Table 8, when the SO ₂ concentration was 0 ppm, there was almost no problem. When the SO ₂ concentration was 1000 ppm, the denitration agents 4 and 5 showed good denitration characteristics. Decreased slightly to 40%.

[0066]

As described above in detail, according to the present invention, a catalyst support is formed using ZSM-5 zeolite as a main raw material, and the ion exchange rate of cobalt or copper supported on the catalyst support is increased. By setting the content to 5 to 30 (%), the denitration rate is remarkably improved as compared with the conventional denitration agent. Although the decomposition characteristics of the substance and the denitration rate are different, a high denitration rate of 85 (%) or more can be obtained using any reducing agent.

Further, since the reduction catalyst does not deteriorate its catalytic performance due to components other than NO _X in the exhaust gas, for example, SO _X or O ₂ , frequent replacement of the catalyst is unnecessary, and urea other than ammonia is used as a reducing agent. , Ammonium carbonate, melamine, light oil and the like are available, so that there is an advantage that no special care is required for handling these reducing agents. Furthermore, since an expensive noble metal catalyst is not used as a reduction catalyst, it is effective from an economical viewpoint.

In particular, according to the present invention, when treating exhaust gas of an internal combustion engine, an optimal catalyst carrier is selected, and an active metal and a reducing agent to be carried on the catalyst carrier are selected. Can be significantly increased.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the configuration of an experimental apparatus for obtaining denitration efficiency using a denitration method according to the present invention.

FIG. 2 is a longitudinal sectional view of a main part of FIG.

FIG. 3 shows N adsorbed on a denitration agent used in this example and a conventional example.
The graph which shows the relationship between the temperature at the time of detecting O with a desorber, and a desorption rate.

[Explanation of symbols]

1 ... reactor 2 ... gas (reducing agent) inlet pipe 3 ... denitrating agent 4 ... insulation heater 5 ... preheater 6 ... (reducing agent) tank 8 ... nozzle 9 ... NO gas cylinder 10 ... N ₂ gas cylinder 11 ... SO ₂ Gas cylinder 12 ... O ₂ gas cylinder 13,14 ... Thermocouple

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiko Asano 2-1-117 Osaki, Shinagawa-ku, Tokyo Inside the Meidensha Co., Ltd. (72) Inventor Tatsutoshi Tamura 2-1-1, Osaki, Shinagawa-ku, Tokyo Stock Company Inside the company Meidensha (72) Inventor Masahiko Ieda 2-1-1-17 Osaki, Shinagawa-ku, Tokyo Inside the company Meidensha

Claims (4)

[Claims] In the method of removing the 1. A nitrogen oxide in the exhaust gas and the carrier the active metal be supported denitrating agent and NO _X containing gas obtained catalyst so as to catalytically reacting in the presence of a reducing agent, Using ZSM-5 type zeolite as a main raw material, calcination and honeycomb forming are performed to form a catalyst carrier. Cobalt or copper is supported on the catalyst carrier as a metal catalyst by an ion exchange method, and ammonia water, urea containing ammonia, urea containing A method for removing nitrogen oxides in exhaust gas, characterized by using ammonium or melamine. 2. The method according to claim 1, wherein the zeolite before the sintering process is immersed in an acetate or nitrate solution containing cobalt ions or copper ions, and the mixture is stirred for several hours while heating, thereby performing ion exchange of cobalt or copper. Item 1
The method for removing nitrogen oxides in exhaust gas as described above. 3. An NH ₄ -ZSM-5 zeolite as a main raw material is formed and calcined to obtain H-type H-ZSM-5, with an ion exchange rate of 5 to 30 (%) and ion exchange of cobalt or copper. 3. The method for removing nitrogen oxides in exhaust gas according to claim 1, wherein the method is performed. 4. The method according to claim 1, wherein light oil is used as the reducing agent, and light oil / NO is added to the denitration agent at a ratio of 0.5. Removal method.