Denitrification catalyst for individual or simultaneous use of hydrocarbon and ammonia as reducing agents, method for preparing denitrification catalyst, and selective catalytic reducing apparatus comprising same

Abstract

The objective of the present invention is to provide a high-efficiency denitrification catalyst in which denitrification performance does not deteriorate even if at least two types of reducing agents are individually or simultaneously used to mix and use various reducing agents. The catalyst includes Cu and Ag ion-exchanged and impregnated in zeolite, and may comprise the steps of: preparing a metal ion solution; mixing the metal ion solution with zeolite; reacting the metal ion solution with the zeolite; drying the reacted zeolite; firing the dried zeolite; and coating a monolith carrier with the prepared catalyst.

Description

A denitrification catalyst capable of using hydrocarbons and ammonia as reducing agents alone or in combination, a method for producing a denitrification catalyst, and a selective catalytic reduction device comprising the same

[0001] The present invention relates to a denitrification catalyst, and more specifically, to a denitrification catalyst suitable for using ammonia and hydrocarbons in exhaust gas as reducing agents in order to treat nitrogen oxides contained in exhaust gas, a method for producing the denitrification catalyst, and a selective catalytic reduction device including the same.

[0002] Nitrogen oxides, a representative pollutant generated from fuel combustion facilities such as kilns, power plants, boilers, and incinerators, cannot be directly released into the atmosphere from an air pollution prevention perspective and are therefore subject to removal. In particular, nitrogen oxides pose a serious threat to the human body, causing respiratory problems and photochemical smog, thus contributing to serious environmental pollution problems.

[0003] To date, in order to treat the above nitrogen oxides, combustion methods such as combustion using non-excess air and combustion temperature control have been improved, and nitrogen oxides have been treated using cleaning technology, selective catalytic reduction technology, and selective non-catalytic reduction technology.

[0004] Such combustion facilities generate large amounts of exhaust gas, which includes regulated components such as NOx, CO, VOCs, NH3, and SO2. As regulations on fine dust (photochemical smog) have been strengthened recently, there is a growing demand for reductions in NOx, VOCs, and odors, and new technologies are needed to improve these.

[0005] Commercially available SCR catalysts using ammonia (NH3) as a reducing agent primarily consist of vanadium-based catalysts. These catalysts exhibit excellent activity in the temperature range of 280–320°C, but exhibit very poor denitrification performance for hydrocarbon SCR (HC-SCR).

[0006] In addition, metal catalysts such as Fe or Cu supported on zeolite are being discussed as denitrification catalysts using NH3 as a reducing agent for SCR catalysts. In addition to the NH3-SCR reaction using NH3 or urea, research is also being conducted on HC-SCR that reduces the amount of NH3 used or uses HC as a reducing agent without using NH3. Typically, catalysts supported on zeolite, alumina, or titania are used, with precious metals such as Pt, Pd, and Cu, Fe, Ag, Mn, and Zn.

[0007] In addition, since the conventional denitrification catalyst using NH3 as a reducing agent has poor denitrification performance in an environment where HC is emitted, it is necessary to pre-treat HC before the denitrification process.

[0008] Meanwhile, HC-SCR is primarily used for the denitrification of automobile exhaust gases, and there are also HC-SCRs applied to stationary pollutants emitted by other industries. However, there is the problem of requiring additional reducing agents when HC concentrations are low. While HC and NH3 can be used as reducing agents, there is a problem of NH3 denitrification performance deteriorating due to HC poisoning when both are used together or when large amounts of HC are present in the exhaust gas.

[0009] In order to solve the problems of the above-mentioned prior art, the present invention aims to provide a denitrification catalyst capable of using HC and NH3 present in exhaust gas in combination as reducing agents.

[0010] The present invention aims to provide a denitrification catalyst that is active both singly and in combination with NH3 and HC as reducing agents.

[0011] In addition, the present invention aims to provide a denitrification catalyst suitable for denitrification of exhaust gas containing ammonia or hydrocarbons.

[0012] In addition, the present invention aims to provide a denitrification catalyst that can operate even in an environment with a low hydrocarbon concentration compared to the NOx concentration.

[0013] In addition, the present invention aims to provide a denitrification catalyst that is not limited in the active temperature range and can be applied particularly to high-temperature regions by being installed in thermal storage oxidation, thermal storage catalytic oxidation, and catalytic oxidation facilities.

[0014] In addition, the present invention aims to provide a method for producing the above-described denitrification catalyst.

[0015] In addition, the present invention aims to provide a selective catalytic reduction device having the above-described denitrification catalyst.

[0016] In addition, the present invention aims to provide a selective catalytic reduction method using a selective catalytic reduction device equipped with the aforementioned denitrification catalyst.

[0017] According to one aspect of the present invention for achieving the above technical task, the present invention provides a method for producing a denitrification catalyst, comprising the steps of: preparing a metal ion solution; mixing the metal ion solution with a zeolite; reacting the metal ion solution with the zeolite; drying the reacted zeolite; and calcining the dried zeolite.

[0018] In the present invention, the metal ion solution may include Cu ions and Ag ions.

[0019] In the present invention, in the mixing step, 1 to 25 parts by weight of Cu and 0.1 to 5 parts by weight of Ag can be mixed with respect to 100 parts by weight of the zeolite.

[0020] In the present invention, the zeolite may have a Si / Al weight ratio of 10 to 40.

[0021] Additionally, the reaction step may include a step of evaporating the solvent of the metal ion solution under reduced pressure conditions.

[0022] Additionally, the above reaction step can be performed at a pressure of 100 to 400 mbar.

[0023] In the present invention, the reaction step may include a step of ion-exchanging metal ions of a metal ion solution with metal ions of zeolite.

[0024] Additionally, the reaction step may include a step of impregnating the zeolite with metal ions of a metal ion solution.

[0025] The manufacturing method of the present invention may further include a step of preparing a coating solution containing the calcined zeolite and an inorganic binder, a step of immersing a carrier in the coating solution, and a step of calcining the immersed carrier.

[0026] At this time, the coating solution may contain 1 to 10% by weight of an inorganic binder relative to 100 parts by weight of zeolite.

[0027] In order to achieve the above other technical tasks, the present invention provides a denitrification catalyst comprising a carrier; and a zeolite catalyst impregnated and ion-exchanged with Cu and Ag, which is coated on the surface of the carrier.

[0028] In the present invention, the catalyst may contain 1 to 25 parts by weight of Cu and 0.1 to 5 parts by weight of Ag per 100 parts by weight of zeolite.

[0029] According to one aspect of the present invention for achieving the above technical task, the present invention provides a denitrification device for denitrifying an exhaust gas stream containing NOx, wherein the denitrification device may be equipped with a reactor equipped with a zeolite catalyst impregnated and ion-exchanged with Cu and Ag, which is coated on a carrier and a surface of the carrier; and a heating furnace for controlling the temperature of the reactor.

[0030] In the present invention, the temperature of the reactor can be maintained at a temperature of 300°C or higher. In addition, the temperature of the reactor can be maintained at a temperature of 450°C or lower.

[0031] In the present invention, the denitrification device may further include a reducing agent stream supply device that supplies at least one reducing agent stream selected from the group consisting of HC, ammonia, and urea.

[0032] According to one aspect of the present invention for achieving the above technical task, the present invention provides a denitrification method for denitrifying an exhaust gas stream containing NOx, comprising the steps of introducing the exhaust gas stream into a reactor equipped with a carrier and a zeolite catalyst impregnated and ion-exchanged with Cu and Ag coated on the surface of the carrier; and the step of denitrifying by maintaining the temperature of the reactor at a temperature of 300°C or higher.

[0033] In the present invention, the temperature of the reactor can be maintained at a temperature of 450°C or lower.

[0034] In the denitrification device or denitrification method of the present invention, the space velocity is 4,000 to 25,000 hr. -1 can be performed in , preferably 4,000 to 10,000 hr -1 is suitable.

[0035] According to the present invention, it is possible to provide a catalyst having high-efficiency denitrification performance by using NH3 and HC alone or in combination for a denitrification effect.

[0036] Furthermore, according to the present invention, a denitrification catalyst can be provided that does not require the introduction of a separate reducing agent when applied to exhaust gas containing NH3 or HC. Furthermore, a denitrification catalyst whose NH3 denitrification performance is not degraded due to poisoning can be provided even when a large amount of HC is present in the actual exhaust gas.

[0037] In addition, according to the present invention, it is possible to provide a selective catalytic reduction device that is efficient and economical for denitrification by having the above-described denitrification catalyst.

[0038] Figure 1 is a flow chart illustrating a catalyst manufacturing method according to one embodiment of the present invention.

[0039] Figure 2 is a flow chart illustrating a catalyst coating process according to one embodiment of the present invention.

[0040] FIG. 3 is a drawing illustrating a denitrification catalyst having a monolithic structure manufactured according to one embodiment of the present invention.

[0041] Figure 4 is a drawing illustrating a performance evaluation device for a denitrification catalyst in the present invention.

[0042] Figures 5 and 6 are graphs showing denitrification efficiency measured according to one embodiment of the present invention.

[0043] Figure 7 is a graph showing the results of measuring denitrification efficiency under different denitrification conditions according to another embodiment of the present invention.

[0044] Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

[0045]

[0046] Figure 1 is a flow chart illustrating a catalyst manufacturing method according to one embodiment of the present invention.

[0047] Referring to Fig. 1, an aqueous solution containing Cu ions and Ag ions, represented by CuX as a Cu precursor and AgX as an Ag precursor (wherein X includes at least one compound selected from the group consisting of Cl, NO3, CH3COO, and SO3), is prepared (S110).

[0048] In the present invention, the metal ions in the metal salt aqueous solution react with zeolite in a subsequent mixing process to be ion-exchanged with the cations of the zeolite or impregnated with the metal ions. Preferably, the gas in the zeolite pores is removed under reduced pressure conditions so that the metal salt aqueous solution can penetrate into the pores, thereby supporting the active metal on the surface and inside the pores, and the vacuum is set to 500 mbar or less. At this time, the ion-exchanged and supported Cu 2+ , Cu+ , CuO acts as an active site to reduce NO, and Ag ions protect Cu cation species and Cu + / Cu 2+ Metal ions can enhance reactivity by promoting the redox cycle of zeolites. In addition, metal ions can inhibit dealumination of zeolites under moist conditions.

[0049] The prepared metal salt aqueous solution is mixed with zeolite (S130). In the present invention, ZSM-5, Y-zeolite, Mordenite, BEA, SSZ-13, etc. can be used as the zeolite. In the present invention, it is preferable that the zeolite has a Si / Al weight ratio of 40 or less, 35 or less, or 30 or less. In the present invention, the Si / Al weight ratio of the zeolite may be 5 or more, 10 or more, 15 or more, or 20 or more. In addition, the Si / Al weight ratio of the zeolite may be 50 or less, 40 or less, or 30 or less. Preferably, the Si / Al weight ratio is 10 to 40.

[0050] At this time, it is preferable that the metal salt mixed with respect to 100 parts by weight of the zeolite contains 1 to 25 parts by weight of Cu and 0.1 to 5 parts by weight of Ag based on the metal content.

[0051] Next, the mixed solution is reacted to exchange the metal ions in the aqueous solution with the cations of the zeolite and support them on the surface and inside the pores of the zeolite (S150). In the step of supporting the metal ions, it is preferable to perform the temperature at 10 to 120 degrees. More preferably, the step of supporting them is preferably performed using a vacuum rotary evaporator. In the present invention, the reaction may be performed at a rotation speed of 50 to 200 rpm, a temperature of 10 to 80 degrees, and for 1 to 10 hours in the vacuum rotary evaporator. At this time, the vacuum rotary evaporator is placed in a water bath maintained at a constant temperature (e.g., 80 degrees Celsius), and the inside of the evaporator is depressurized or the temperature is increased, thereby shortening the slurry drying time and facilitating the impregnation of the catalytically active material into the pores of the zeolite. Maintaining the pressure is reduced, so that the precursor solution enters the pores of the zeolite particles, enabling metal impregnation not only on the surface but also inside the pores of the zeolite particles. In the present invention, the vacuum level of the evaporator may be 500 mbar or less, 400 mbar or less, or 300 mbar or less. In addition, it is preferable that the vacuum level of the evaporator be maintained at 100 mbar or more, 150 mbar or more, or 200 mbar or more.

[0052]

[0053] At this time, the mechanism by which the metal ions in the aqueous solution bind to the zeolite is not limited to ion exchange, and it is of course possible to bind by impregnation simultaneously with ion exchange.

[0054] Once the reaction is complete, the reacted zeolite is dried (S170). The drying step can be performed at a temperature of 100°C or higher for 5 hours or longer. Once drying is complete, the zeolite, which has undergone ion exchange and impregnation, is calcined. In the present invention, the calcination step can be performed at a temperature of 400 to 600°C or higher for 1 to 5 hours.

[0055] The content of the metal component in the zeolite catalyst manufactured in the present invention may be 1 part by weight or more, 2 parts by weight or more, 3 parts by weight or more, 4 parts by weight or more, 5 parts by weight or more, or 6 parts by weight or more, based on 100 parts by weight of the zeolite. In addition, the content of the metal component in the zeolite catalyst in the present invention may be 30 parts by weight or less, 25 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less, or 10 parts by weight or less, based on 100 parts by weight of the zeolite. Preferably, the content of the metal component is 1 to 25 parts by weight of Cu and 0.1 to 5 parts by weight of Ag.

[0056] In the present invention, it is preferable that the ratio of Cu:Ag among the metal components exchanged and impregnated in the zeolite is in the range of 10:1 to 1:1.

[0057]

[0058] Referring to the following Figure 2, the catalyst coating process is described.

[0059] Referring to FIG. 2, a coating solution containing the catalyst and inorganic binder manufactured in FIG. 1 is prepared (S210).

[0060] At this time, the inorganic binder in the coating solution may be alumina sol, silica sol, titania sol, aluminosilicate sol, etc., and among them, it is preferable to use alumina sol and silica sol.

[0061]

[0062] Next, it is preferable that the inorganic binder be included in an amount of 1 to 10% by weight per 100 parts by weight of zeolite.

[0063] Next, the ceramic carrier is immersed in the prepared coating solution (S230). At this time, the carrier may be a monolith made of cordierite or mullite. The immersion process is preferably performed more than once. The loading amount of the catalytically active material during the immersion process may be set to 50 to 200 g / L.

[0064] Next, the catalyst-coated ceramic carrier is fired.

[0065] FIG. 3 is a drawing illustrating a denitrification catalyst having a coated monolithic structure according to one embodiment of the present invention.

[0066]

[0067] <Example>

[0068] AgNO31.6g, CuNO319.2g were dissolved in 100 ml of water and stirred at 300 rpm for 1 h.

[0069] The stirred metal ion solution was mixed with 100 g of zeolite ZSM-5 and placed in a vacuum rotary evaporator, and mixed at 100 rpm.

[0070] Next, the vacuum rotary evaporator containing the mixed solution was placed in an 80°C water bath and reacted while maintaining the pressure at 200-300 mbar until the moisture evaporated.

[0071] The zeolite after reaction was dried in a 105℃ dry oven for 8 hours and then calcined at 550℃ for 3 hours. At this time, the heating rate was 5℃ / min, and calcination was performed in an air atmosphere.

[0072] 30 g of calcined zeolite catalyst was dispersed in 100 ml of aqueous solution and stirred at 300 rpm for 30 min. 1.5 g of silica sol was added to the stirred solution and stirred at 300 rpm for 30 min.

[0073] The stirred catalyst solution was immersed in a ceramic monolith-shaped carrier, coated 2-3 times, and then calcined at 550°C for 3 h. The heating rate was 5°C / min, and the calcination was performed in an air atmosphere.

[0074] The Cu and Ag contents of the catalyst manufactured in the above example are 5 parts by weight and 1 part by weight, respectively, based on 100 parts by weight of zeolite.

[0075]

[0076] <Comparative Example>

[0077] NH4VO33.9g, (NH4)6W 12 O 39 ·6.4 g of H2O was dissolved in 100 ml of water and stirred at 300 rpm for 1 h. The stirred metal ion solution was mixed with 100 g of TiO2 and placed in a vacuum rotary evaporator, where it was mixed at 100 rpm.

[0078] Next, the vacuum rotary evaporator containing the mixed solution was placed in an 80°C water bath and reacted while maintaining the pressure at 200-300 mbar until the moisture evaporated.

[0079] The reacted TiO2 was dried in a 105℃ dry oven for 8 hours and then calcined at 600℃ for 3 hours. At this time, the heating rate was 5℃ / min, and the calcination was performed in an air atmosphere.

[0080] 30 g of the calcined catalyst was dispersed in 100 ml of aqueous solution and stirred at 300 rpm for 30 min. 1.5 g of silica sol was added to the stirred solution and stirred at 300 rpm for 30 min.

[0081] The stirred catalyst solution was immersed in a ceramic monolith-shaped carrier, coated 2-3 times, and then calcined at 600°C for 3 h. The heating rate was 5°C / min, and calcination was performed in an air atmosphere.

[0082] The catalyst manufactured as the above comparative example is a monolithic catalyst coated on TiO2 using vanadium oxide (V2O5) and tungsten oxide (WO3) as active materials, and is a catalyst commonly used in NH3-SCR.

[0083] The V and W contents of the catalyst manufactured in the above comparative example are 3 parts by weight and 6 parts by weight, respectively, based on 100 parts by weight of TiO2.

[0084]

[0085] Hereinafter, a denitrification method according to one embodiment of the present invention will be described. While toluene is used as the HC in the following examples, the present invention is not limited thereto. For example, various hydrocarbon compounds such as toluene, propane, propylene, benzene, and ethanol can be used as the HC.

[0086]

[0087] Experimental Example 1

[0088] Figure 4 is a drawing illustrating a performance evaluation device for a denitrification catalyst manufactured in the present invention.

[0089] Referring to the drawing, the device has multiple gas sources including NO. The gas sources include NH3, C7H8, NO, N2, and Air. Here, C7H8 gas and NH3 gas are used as reducing agents, and N2 and Air are used to adjust the C7H8 concentration and oxygen concentration.

[0090] The experimental device is largely composed of a gas supply system, a temperature output device, a reactor, and an analysis device. The gases used in the experiment were NH3, NO, C7H8, N2, and Air, each using a flow control device (MFC). A furnace and a thermocouple were used to check and control the temperature of the reactor. The reactor was made of stainless steel and a catalyst cut to a volume of 28x28x20mm was placed therein for evaluation. In addition, a Shimadzu gas chromatograph (GC) and a Testo flue gas analyzer were used to measure O2, NO, and NO at the front and rear of the reactor. x , NH3, C7H8 gas concentrations were measured.

[0091] The catalysts of the examples and comparative examples were loaded into the reactor, and the denitrification efficiency was evaluated while varying the temperature of the furnace. The experimental conditions were as follows.

[0092] NO concentration: 250 ppm

[0093] NH3 concentration: 375 ppm

[0094] C7H8 concentration: 500ppm

[0095] O2 concentration: 10%

[0096]

[0097] N2balance

[0098] Q=1.5L / min

[0099] Reactor temperature: 250~500℃

[0100] GHSV(Gas hourly space velocity)=5740h -1

[0101]

[0102] Denitrification efficiency was calculated using the following formula.

[0103] Denitrification efficiency (%) = (1-NOx concentration before reaction / NOx concentration after reaction) x 100

[0104] Table 1 below is a graph showing the results of denitrification efficiency measurements.

[0105] Temperature (℃) Denitrification efficiency (%) Example catalyst Comparative example catalyst 25051.613.530085.323.935094.318.740089.020.945080.420.050070.1-

[0106] Referring to Table 1, the catalyst of Example 1 is characterized by excellent denitrification performance at temperatures above 300°C. This is because when NH3 and toluene are injected simultaneously, the denitrification performance decreases due to toluene poisoning, but the catalyst of the example can secure excellent denitrification performance without toluene poisoning at temperatures above 300°C. The catalyst of the comparative example is a catalyst that is active solely on NH3, and when toluene is injected together, the denitrification performance is low over the entire temperature range due to poisoning.

[0107]

[0108] Experimental Example 2

[0109] The catalyst of the example was loaded into a reactor using the same device as Experimental Example 1, and the denitrification efficiency was measured by varying the NH3 / HC ratio. The measurement conditions were as follows.

[0110]

[0111] NO concentration: 220 ppm

[0112] NH3 concentration: 0~320ppm

[0113] C7H8 concentration: 0~500ppm,

[0114] O2 concentration: 10%

[0115] N2balance

[0116] Q=1.5L / min

[0117] Reactor temperature: 350℃

[0118] GHSV=5740h -1

[0119]

[0120] Figure 5 is a graph showing the denitrification efficiency measured in Experimental Example 2.

[0121] Referring to Fig. 5, it can be seen that a nearly constant denitrification efficiency is obtained regardless of the concentration ratio of the reducing agent.

[0122]

[0123] <Comparative Experiment Example 1>

[0124] The catalyst of the comparative example was loaded into the reactor using the same device as Experimental Example 1, and the denitrification efficiency was measured by varying the NH3 / HC ratio. The measurement conditions were as follows.

[0125] NO concentration: 250 ppm

[0126] NH3 concentration: 0~250ppm

[0127] C7H8 concentration: 0~500ppm,

[0128] O2 concentration: 10%

[0129] N2balance

[0130] Q=1.5L / min

[0131] Reactor temperature: 350℃

[0132] GHSV=5740h -1

[0133]

[0134] Figure 6 is a graph showing the denitrification efficiency measured in comparative experimental example 1.

[0135] Referring to Fig. 6, it can be seen that the denitrification efficiency of the catalyst of the comparative example rapidly decreases due to toluene poisoning when HC is injected, and when HC alone is used as a reducing agent, the denitrification efficiency decreases to less than 20%.

[0136]

[0137] Experimental Example 3

[0138] The denitrification efficiency was evaluated by using the device of Experimental Example 1 and the denitrification catalyst manufactured in the examples under constant temperature (400°C) conditions and varying reducing agent injection conditions.

[0139] NO concentration: 150 ppm

[0140] NH3 concentration: 0~150ppm

[0141] C7H8 concentration: 0~600ppm,

[0142] O2balance

[0143] Q=1.5L / min

[0144] Reactor temperature: 400℃

[0145] GHSV=6600h -1

[0146]

[0147] Figure 7 is a graph showing the results of measuring denitrification efficiency while changing the concentration of C7H8 and NH3.

[0148] At 400℃, no decrease in activity was observed due to simultaneous injection of NH3 and toluene, and denitrification efficiency was found to increase when additional NH3 was injected even when C7H8 used as a reducing agent was insufficient. Furthermore, high denitrification efficiency can be secured by C7H8 injection even when the amount of NH3 injected is less than the theoretical NSR=1.

[0149] The present invention is applicable to a denitrification catalyst and a selective catalytic reduction device.

Claims

1. Step of preparing a metal ion solution; A step of mixing the above metal ion solution and zeolite; A step of reacting a metal ion solution with zeolite; A step of drying the above reacted zeolite; and A method for producing a denitrification catalyst, comprising the step of calcining the dried zeolite.

2. In paragraph 1, A method for producing a denitrification catalyst, wherein the metal ion solution contains Cu ions and Ag ions.

3. In paragraph 2, The above mixing step is, A method for producing a denitrification catalyst, wherein 1 to 25 parts by weight of Cu and 0.1 to 5 parts by weight of Ag are mixed with 100 parts by weight of the above zeolite.

4. In paragraph 1, A method for producing a denitrification catalyst, wherein the above zeolite has a Si / Al weight ratio of 10 to 40.

5. In paragraph 1, A method for producing a denitrification catalyst, wherein the above reaction step comprises a step of evaporating a solvent of the metal ion solution under reduced pressure conditions.

6. In paragraph 5, The above reaction steps are: A method for producing a denitrification catalyst, performed at a pressure of 100 to 400 mbar.

7. In paragraph 1, The above reaction steps are: A method for producing a denitrification catalyst, comprising a step of ion-exchanging metal ions of a metal ion solution with metal ions of zeolite.

8. In paragraph 7, The above reaction steps are: A method for producing a denitrification catalyst, comprising a step of impregnating the zeolite with metal ions of a metal ion solution.

9. In paragraph 1, A step of preparing a coating solution comprising the above-mentioned calcined zeolite and an inorganic binder; A step of immersing a carrier in the above coating solution; and A method for producing a denitrification catalyst, comprising the step of calcining a immersed carrier.

10. In paragraph 9, A method for producing a denitrification catalyst, wherein the coating solution contains 1 to 10% by weight of an inorganic binder based on 100 parts by weight of zeolite. 11.Carrier; and Comprising a zeolite catalyst impregnated and ion-exchanged with Cu and Ag, which is coated on the surface of the carrier, 12. In paragraph 11. The above catalyst is a catalyst carrier for denitrification containing 1 to 25 parts by weight of Cu and 0.1 to 5 parts by weight of Ag per 100 parts by weight of zeolite.

13. In a denitrification device for denitrifying an exhaust gas stream containing NOx, The above denitrification device comprises a reactor equipped with a carrier and a zeolite catalyst impregnated and ion-exchanged with Cu and Ag, which is coated on the surface of the carrier; and A denitrification device characterized by having a heating furnace for controlling the temperature of the reactor.

14. In paragraph 13, A denitrification device in which the temperature of the above reactor is maintained at a temperature of 300℃ or higher.

15. In paragraph 14, A denitrification device in which the temperature of the above reactor is maintained at a temperature of 450℃ or less.

16. In paragraph 13, The above denitrification device is, A denitrification device further comprising a reducing agent stream supply device supplying at least one reducing agent stream selected from the group consisting of HC, ammonia and urea.

17. A method for denitrifying an exhaust gas stream containing NOx, A step of introducing the above exhaust gas stream into a reactor equipped with a carrier and a zeolite catalyst impregnated and ion-exchanged with Cu and Ag coated on the surface of the carrier; A denitrification method, comprising a step of denitrifying by maintaining the temperature of the reactor at a temperature of 300°C or higher.

18. In paragraph 17, A denitrification method in which the temperature of the above reactor is maintained at a temperature of 450℃ or less.

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