KR100453380B1 - Cocation exchange ferrierite catalyst for and mothod of removing nitrogen oxide - Google Patents

Abstract

The present invention relates to a cation exchange ferrierite catalyst for removing nitrogen oxides and a method for removing nitrogen oxides using the same, and more particularly, nitrogen oxides from a reaction gas containing nitrogen oxides and 2 to 20% by weight of water. In the removal, ferrierite is sequentially added with 0.1 to 4.5% by weight of one metal selected from the group consisting of palladium, platinum, lanthanum, iridium, indium and strontium and 1.0 to 6.0% by weight of cobalt based on the total weight of the catalyst. Or it relates to a positive ion exchange ferrierite catalyst for removing nitrogen oxides at the same time and a method for removing nitrogen oxides using the same. According to the present invention, in a nitrogen oxide removal reaction using saturated and unsaturated hydrocarbons having 1 to 4 carbon atoms, especially methane, as a reducing agent, a combustion product using a cationic ion exchange ferrite catalyst having excellent durability against water Even when water is present in the phosphorus reaction gas, it is possible to achieve excellent nitrogen oxide removal efficiency.

Description

Cation exchange ferrierite catalyst for and mothod of removing nitrogen oxide

The present invention relates to a cation exchange ferrierite catalyst for nitrogen oxide removal and a method for removing nitrogen oxide using the same, and more particularly, one metal selected from the group consisting of palladium, platinum, iridium and indium in ferrierite. The present invention relates to a cation exchange ferrilite catalyst for nitrogen oxide removal and a method for removing nitrogen oxide using the same, which have excellent nitrogen oxide removal efficiency even when water is present in the combustion product by sequentially or simultaneously exchanging cobalt.

The best nitrogen oxide removal technology developed so far is a selective catalytic reduction (SCR) method using ammonia (NH ₃ ) as a reducing agent on the vanadia / titania catalyst system. It is evaluated as the most efficient method and has been commercialized since the 1960s and applied to the actual process. However, according to the above technique, in recent years, due to the transport and storage of ammonia as a reducing agent, the safety, the problem of corrosion of the device and the air pollution caused by the second unreacted ammonia slip, alternative reducing agents and their Attention has been drawn to the development of decisive catalysts in the technologies used {M. Iwamoto and H. Hamada, Catal. Today, 10 (1991) 57}.

On the other hand, attempts to use hydrocarbons, which are one of the alternative reducing agents, have emerged as the main research topics of many researchers since Held et al. Experimented under conditions simulating actual exhaust gas, and especially C ₂ or more unsaturated hydrocarbons. Research is concentrated. On the other hand, ZSM-5, in which copper (Cu) is ion-exchanged, is known to have relatively good activity among the various catalysts used in such hydrocarbon-SCR.

In particular, the methane of the hydrocarbon reducing agent was classified as a non-selective reducing agent with other C ₂ or more of the conventional hydrocarbon {M. Iwamoto and H. Hamada, Catal. Today, 10 (1991) 57}, Li and Armor {Y. Li and JN Armor, Appl. Catal. B, 1 (1992) L31} has focused on the utility of methane as a selective reducing agent. Several catalysts have been proposed in this methane-SCR reaction system, especially cobalt-ion exchanged ferrierite catalysts, but active at a reaction temperature of 450-500 ° C when 2% water is present in the reaction gas. This has the disadvantage of reducing by 5-25%.

In addition, the combustion reaction of the methane is also required high temperature on precious metal catalysts such as platinum (Pt), palladium (Pd) and rhodium (Rh) {OJ Adlhart, SG Hindin and RE Kenson, Chem. Eng. Prog., 76 (1991) 73}, C ₂ or more saturated hydrocarbon series or unsaturated hydrocarbon series is less difficult to activate at lower temperatures. However, this aspect is fundamentally solved at the catalyst design stage and attracts attention because of the advantages of methane itself as a reducing agent. In other words, natural gas with 85% of methane as the main component is used as a general purpose fuel, and there is a relatively small risk of environmental pollution during transportation due to the construction of a single supply facility through a buried pipeline network. In order to minimize emissions, natural gas is mainly used as the main fuel. Therefore, if unburned methane is used to remove nitrogen oxides emitted from such a large combustion facility, there is an advantage that it can be applied to a real process without the addition of additional reducing agent.

For example, Li and Armor {Y. Li and JN Armor, Appl. Catal. The study of B, 1 (1992) L31} discloses that the cobalt ion-bound ZSM-5 (Si / Al = 14) catalyst exhibits very good activity even in the presence of excess oxygen in the methane-SCR reaction. That is, 820 ppm of nitrogen monoxide present with 2.5% of oxygen and 2000 ppm or more of methane at a reaction temperature of 400 ° C. and a space velocity of 7,500 h ⁻¹ can be 100% removed, especially cobalt ion-exchanged in ferrierite. It is disclosed that it is more effective in the case (Co-FER). However, even in the method according to the above document, there is a problem in that activity decreases in the presence of moisture.

U.S. Patent No. 5,260,043 also discloses a catalyst that can selectively remove nitrogen oxides in combustion gases using methane as a reducing agent. According to the patent, the nitrogen oxide removal rate was investigated on zeolites in which transition metals were exchanged under various reaction conditions and on catalysts carrying niobium (Nb) or aluminum (Al) in addition to these catalysts. -5 discloses the most effective.

However, the catalytic activity investigated in the above documents and patents is the result of the absence of water, especially in the case of the method according to the patent, when the reaction temperature of 250 to 500 ° C. is present at a reaction temperature of 250 to 500 ° C. when 2% of water is present on the same catalyst. A 30% decrease in activity was observed {Y. Li, P. J. Battavio, J. N. Armor, J. Catal., 142 (1993) 561}. In the case of Co-FER catalysts irradiated together, deactivation of about 10 to 35% occurs when 2% of water is present at a reaction temperature of 500 to 600 ° C. Li, J. N. Armor, Appl. Catal. B, 3 (1993) L1}.

As described above, regardless of the zeolite structure selected, the activity of the catalyst for nitrogen oxide removal is severely reduced by water when it is ion exchanged with only cobalt. Therefore, the most important part in using a zeolite having ion exchanged transition metals as a catalyst for removing nitrogen oxides using methane as a reducing agent is durability against water coexisting in the exhaust gas. In general, since 2 to 18% of water is present in the form of water vapor along with nitrogen oxide in the exhaust gas emitted from most combustion processes, the strong durability of the target catalyst to water can be said to be a top priority for commercialization. Therefore, there is a need for a technology that can drastically improve such a decrease in catalytic activity caused by water.

In order to solve the problems as described above, a method of constructing a cationic ion system by selecting an effective zeolite structure and then ion-exchanging at least two or more kinds of transition metals simultaneously or sequentially has been studied.

For example, Gutierrez et al. {L. Gutierrez, A. Boix and J. O. Petunchi, Catal. Today, 54 (1999) 451} show that when platinum is ion-exchanged in mordenite, ferrilite and ZSM-5 and then cobalt is exchanged, one transition metal is exchanged in each zeolite. It is disclosed that excellent nitrogen oxide removal activity and durability against water can be obtained.

In addition, Ogura et al. {M. Ogura, Y. Sugiura, M. Hayashi and E. Kikuchi, Catal. Lett., 42 (1996) 185} reported the effect by palladium. A first ion-exchange ZSM-5, and then the cobalt, about 12,000h hour the reaction gas consisting of 10% water, 10% oxygen, nitrous oxide, and methane 100ppm 2,000ppm on the PdCo-ZSM-5 catalyst prepared by exchanging ^{palladium- When} injected at a space velocity of ¹ , the activity decrease by water was about 5-10% at the reaction temperature of 300-500 ° C, and the denitrification activity was 80% or more at 400-500 ° C.

Kikuchi et al. {E. Kikuchi, M. Ogura, N. Aratani, Y. Sugiura, S. Hiromoto and K. Yogo, Catal. Today, 27 (1996) 35} exchanged precious metals such as platinum, rhodium (Rh), and iridium with conjugated ions in the In-ZSM-5 catalyst to obtain water at 1,000 ppm of methane, 1,000 ppm of nitrogen monoxide, and 10% oxygen. Although 10% coexist, 10% denitrification activity was reported to be improved to 15, 17 and 20% at 500 ° C, respectively.

However, the method according to the above documents also exhibits a decrease in activity in the presence of water, and even if improved, the extent thereof is very insignificant and cannot be widely applied.

Meanwhile, Korean Patent Publication No. 96-13 discloses a method of removing nitrogen oxide in a combustion exhaust gas containing excessive oxygen using methane as a reducing agent on a catalyst. The patent discloses cations selected from the group consisting of cobalt, nickel (Ni), iron (Fe), chromium (Cr), rhodium, gallium (Ga) and manganese (Mn) in mordenite, ZSM-5 and ferrilite zeolites. After ion exchange, the target catalyst was prepared by impregnating another metal selected from the group consisting of niobium (Nb), molybdenum (Mo), silver (Ag), vanadium (V), and manganese. However, the present invention does not mention the durability to water, and there is no right setting for the palladium-cobalt donation system, and a manufacturing method different from the present invention was also used in the preparation method thereof.

EP-A-0,434,063 discloses cobalt-containing zeolite catalysts which are present in cobalt alone or in combination with one or more metals selected from alkaline earth metals and rare earth metals, but in this patent palladium, Only platinum, iridium and indium are disclosed.

In addition, US Pat. No. 6,063,351 discloses a catalyst obtained by ion-exchanging one or more of palladium and cobalt in mordenite in order to remove nitrogen oxides with methane or a mixed gas mainly containing methane as a reducing agent. As a preferred zeolite structure, only mordenite is limited.

As described above, there are several economic and engineering advantages of using hydrocarbons, especially methane, as a reducing agent in the removal of nitrogen oxides by selective catalytic reduction, but for this purpose, methane can serve as a selective reducing agent, as well as water. There is an urgent need for a method for removing nitrogen oxides having a good denitrification activity of 80% or more even in the presence of a large amount of water by using a catalyst having excellent durability.

Accordingly, the present inventors have continued to solve the above-mentioned problems, and as a result, in the nitrogen oxide removal reaction using hydrocarbons, especially methane as a reducing agent, using a cation exchange ferrierite catalyst having excellent durability against water Thus, even when water is present in the reaction gas, a method for achieving excellent nitrogen oxide removal efficiency has been found, and the present invention has been completed based on this.

Accordingly, it is an object of the present invention to provide a cation exchange ferrierite catalyst for removing nitrogen oxides having excellent durability against water.

Another object of the present invention is to provide a nitrogen oxide removal method that can achieve a high nitrogen oxide removal ability in a suitable operating temperature range even when excess water is present in the reaction gas using the catalyst.

The catalyst of the present invention for achieving the above object is in the removal of nitrogen oxides from the reaction gas containing nitrogen oxides and 2 to 20% by weight of water, ferrierite with respect to the total weight of the catalyst, palladium, platinum, lanthanum, iridium 0.1 to 4.5% by weight of one metal selected from the group consisting of, indium, and strontium and 1.0 to 6.0% by weight of cobalt.

The method of the present invention for achieving the above another object is a reaction gas containing nitrogen oxides and 2 to 20% by weight of water in the presence of the ferrierite catalyst to a saturated and unsaturated hydrocarbon having 1 to 4 carbon atoms as a reducing agent It is made to react using.

1 is a graph illustrating a comparison of nitrogen conversion rate when water is not present in a nitrogen oxide reaction using ferrierite catalysts according to Comparative Examples and Examples of the present invention.

2 is a graph showing a comparison of the nitrogen conversion rate when water is present in the nitrogen oxide reaction using the ferrierite catalyst according to the comparative examples and examples of the present invention.

Hereinafter, the present invention will be described in more detail.

According to the present invention, in the removal of nitrogen oxides from a reaction gas containing nitrogen oxides and 2 to 20% by weight of water, a ferrierite (FER) catalyst exchanged with a cobalt-based conjugate ion is used. Durability to water, with 0.1-4.5% by weight of one metal selected from the group consisting of palladium, platinum, lanthanum, iridium, indium, and strontium and 1.0-6.0% by weight cobalt exchanged to the total weight of the catalyst This excellent nitrogen oxide removal cation exchange ferrite zeolite catalyst can be provided. Preferably, 0.1-4.5 wt% of palladium and 1.0-6.0 wt% of cobalt in ferrierite, more preferably 0.3-1.2 wt% of palladium and 2.5-4.5 wt% of cobalt in ferrierite Cationic ion exchange ferrite zeolite catalysts may be provided.

The cationic ion ferrierite catalyst according to the present invention is a wet ion exchange method (WIE) for ion exchange in an aqueous solution or a precursor of a desired metal salt and ferrite, after mechanical stirring, and then heated to an appropriate temperature for ion exchange. It can be prepared by solid-state ion exchange (SSIE), or by mixing the two methods.

In the case of using the wet ion exchange method, the second metal ion other than cobalt is first exchanged in the ammonium zeolite or the cobalt and the second metal ion are simultaneously exchanged prior to ion exchange of the cobalt. Preferably, the second metal ion is one selected from the group consisting of palladium, platinum, lanthanum, iridium, indium, strodium, and the like. Looking at the production method of the cationic ion exchange ferrite zeolite catalyst using the wet ion exchange method in more detail as follows.

The cations (Na ⁺ or K ⁺ ) contained in the powdered ferrierite are first ion-exchanged with ammonium ions (NH ₄ ⁺ ), washed thoroughly with distilled water, and then dried in a drier at 100-120 ° C. for at least 12 hours. The ammonium ferrilite (NH ₄ ⁺ -FER) thus obtained was exchanged with the desired metal ion using an aqueous solution of a precursor of the metal at a desired concentration, and then washed with distilled water sufficiently and dried for at least 12 hours to dry the metal-ferrilite. (M-FER) is obtained. Such M-FER catalyst is preferably calcined at 450 to 550 ° C for 9 to 10 hours. In using this method, the amount of metal exchange is controlled according to the ion exchange time, the number of ion exchanges, the concentration and temperature of the aqueous solution. As described above, according to the method of exchanging the cobalt ion according to the present invention, the ferriteite is first exchanged with a second metal ion and then cobalt ion is exchanged, or the second metal ion and cobalt ion are simultaneously exchanged. Can be performed.

On the other hand, in the case of using the solid ion exchange method, up to the process of preparing NH ₄ -FER is carried out in the same manner as the wet ion exchange method. Then, the dried NH ₄ -FER and the desired metal chloride are mechanically stirred and mixed, and then ion exchanged for several hours at an appropriate temperature, followed by sufficient washing with distilled water and drying to form a cationic ion exchange ferrite zeolite catalyst. Get In this manufacturing method, since the ion exchange is performed in anhydrous state at high temperature, the coordination size of the active metal is smaller than that of the aqueous phase ion exchange. Therefore, the active metal can be ion exchanged relatively easily to the zeolite having a small pore size. In addition, the solid ion exchange method, as is known, can shorten the preparation time of the catalyst compared to the wet ion exchange method, there is an advantage that it is relatively easy to predict the amount of metal ions to be ion exchanged.

According to the present invention, regardless of the ion exchange method described above, the amount of metal donated ions exchanged to the ferrite is, respectively, the second one selected from the group consisting of 1.0 to 6.0% by weight of cobalt, palladium, platinum, iridium and indium. It is preferable that metal is 0.1 to 4.5 weight%. At this time, the nitrogen oxide removal rate is reduced when the amount of exchange of the cobalt and the second metal is out of the range.

According to the present invention, the removal of nitrogen oxides having a high nitrogen oxide removal ability at a proper operating temperature even when excess water is present in the reaction gas by using a positive ion exchange ferrierite catalyst having excellent durability to water as described above. It may provide a method.

The nitrogen oxide removal method using the conjugate ion-exchange ferrierite catalyst of the present invention is a reaction gas containing nitrogen oxide and 2 to 20% by weight of water in the presence of the ferrierite catalyst saturating having a carbon number of 1 to 4 And unsaturated hydrocarbons as the reducing agent.

Reducing agents that can be used in the nitrogen oxide removal method of the present invention are preferably saturated and unsaturated hydrocarbons having 1 to 4 carbon atoms, preferably methane.

On the other hand, the weight ratio of the nitrogen oxide to the reducing agent methane is preferably from 0.05 to 10, preferably from 0.5 to 2.0, the nitrogen oxide removal rate is reduced when the weight ratio is less than 0.05 or more than 10.

According to the present invention, the reaction gas may further include 2 to 20% by weight of water, and even in the presence of such a large amount of water, high nitrogen oxide removal ability may be achieved at an appropriate operating temperature according to the method of the present invention.

Nitrogen oxide removal reaction according to the present invention is carried out at a reaction temperature of 200 ~ 800 ℃, preferably 200 ~ 600 ℃, more preferably 400 ~ 600 ℃, the reaction temperature is less than 200 ℃ or more than 800 ℃ The nitrogen oxide removal rate decreases.

Further, the nitrogen oxide removing reaction in accordance with the present invention is carried out in the hourly space velocity of 3,000~100,000h ^-1, preferably 5,000~30,000h ^-1.

As described above, according to the present invention, in the nitrogen oxide removal reaction using hydrocarbons, in particular methane as the reducing agent, water is present in the reaction gas by using a cation exchange ferrierite catalyst having excellent durability against water. Even in this case, it is possible to provide a method for achieving excellent nitrogen oxide removal efficiency.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited thereto.

Comparative Example 1

Preparation of cobalt ion-exchanged ferrite (Co-FER)

Dissolve 0.002 mole of cobalt acetate in 2 L of distilled water, add 10 g of NH ₄ -FER to it, and ion-exchange at room temperature for 24 hours, wash well with distilled water, and dry the reaction at 110 ° C. for at least 12 hours. The reaction was completed. After repeating the ion exchange step once, the final reactant was calcined at 500 ° C. for 10 hours to prepare 1.5 wt% cobalt-exchanged ferriteite (Co-FER) catalyst.

Comparative Examples 2-4

In order to increase the amount of supported cobalt, except that the number of ion exchange reactions were repeated 2, 3, and 4 times, the same procedure as in Comparative Example 1 was carried out to carry ferrite with 3.6, 5.0, and 6.6 wt% of cobalt, respectively ( Co-FER) catalyst was prepared.

Comparative Example 5

Preparation of Palladium-Ion Exchanged Ferrilite (Pd-FER)

In the same manner as in Comparative Example 1 using 0.0004 mol of palladium nitrate instead of cobalt acetate, a ferrilite catalyst (Pd-FER) having 0.43% by weight of palladium exchanged was prepared.

Example 1

-Preparation of Palladium and Cobalt Ion Exchanged Ferrilite (PdCo-FER) by Wet Ion Exchange

10 g of NH ₄ -FER was added to a solution of 0.0003 mol of palladium nitrate, and ion-exchanged at room temperature for 24 hours, followed by washing with distilled water sufficiently and drying at 110 ° C. for 12 hours or more to complete the palladium ion exchange reaction. The palladium ion exchange reaction step was repeated once to obtain a palladium exchange ferrierite.

Then, the palladium exchange ferrilite obtained above instead of NH ₄ -FER was used, and cobalt ion exchange reaction was completed in the same manner as the ion exchange reaction except that 0.03 mol of cobalt acetate was used instead of palladium nitrate. After repeating the cobalt ion exchange step twice, the final reaction product obtained therefrom was calcined at 500 ° C. for 10 hours for 0.31 wt% of palladium and 5.35 wt% of cobalt-exchanged ferrite catalyst (PdCo -FER) was prepared.

Example 2

A ferrier in which 0.48% by weight of palladium and 2.54% by weight of cobalt were exchanged in the same manner as in Example 1 except that the number of palladium ion exchange reactions and the number of cobalt ion exchange reactions were changed twice and once, respectively. Light catalyst (PdCo-FER) was prepared.

Example 3

Preparation of Palladium and Cobalt Ion Exchanged Ferrite (PdCo-FER) by Solid Ion Exchange

After mechanically stirring 5 g of NH ₄ -FER and 0.04 g of palladium chloride, the mixture was heated to 550 ° C. at a temperature increase rate of 10 ° C./min in a nitrogen atmosphere, held at a temperature of 550 ° C. for 5 hours, and then cooled to room temperature. After washing sufficiently with distilled water and dried for more than 12 hours to complete the palladium ion exchange reaction. The palladium ion exchange reaction step was repeated once to obtain a palladium exchange ferrierite.

Then, the palladium exchange ferrilite obtained above was used instead of NH ₄ -FER, and cobalt ion exchange reaction was completed in the same manner as the ion exchange reaction except that 1.2 g of cobalt chloride was used instead of the palladium chloride. . The cobalt ion exchange reaction was repeated once to prepare a ferrilite (PdCo-FER) catalyst in which 0.45 wt% of palladium and 4.97 wt% of cobalt were exchanged.

Example 4

Except that the palladium chloride and cobalt chloride weight was changed to 0.05 g and 0.4 g, respectively, the same ferriteite catalyst (PdCo- exchanged with 0.55% by weight of palladium and 1.57% by weight of cobalt) was carried out in the same manner as in Example 3. FER) was prepared.

Example 5

Except for changing the palladium chloride and cobalt chloride weight to 0.07g and 1.0g, respectively, the same ferriteite catalyst (PdCo- exchanged with 0.64% by weight of palladium and 4.35% by weight of cobalt) was carried out in the same manner as in Example 3. FER) was prepared.

Example 6

Preparation of Lanthanum-Cobalt-Ion Exchanged Ferrilite (LaCo-FER)

0.28% by weight of lanthanum and 1.52 in the same manner as in Example 1, except that 0.02 mol of lanthanum nitrate was used instead of palladium nitrate, followed by one ion exchange using 0.02 mol of cobalt acetate. A Ferrilite catalyst (LaCo-FER) in which weight percent cobalt was exchanged was prepared.

Example 7

Ferrier in which 0.13% by weight of lanthanum and 3.22% by weight of cobalt were exchanged in the same manner as in Example 6 except that the number of times of lanthanum ion exchange reaction and the number of cobalt ion exchange reactions were changed once and twice, respectively. Light catalyst (LaCo-FER) was prepared.

Example 8

Preparation of InCo-FER with Indium-Cobalt Ion-Exchanged

0.23% by weight of indium and in the same manner as in Example 1 except for the one-time ion exchange reaction using 0.02 mol of indium nitrate instead of lanthanum nitrate, followed by one ion exchange reaction using 0.02 mol of cobalt acetate. A ferrierite catalyst (InCo-FER) with 1.59% by weight of cobalt was prepared.

Example 9

Preparation of SterCo-FER with Strontium-Cobalt Ion Exchange

0.31% by weight of strontium and the same as in Example 1 except that the ion-exchange reaction using 0.02 mol of strontium nitrate instead of lanthanum nitrate, and then ion-exchange four times using 0.02 mol of cobalt acetate 5.20 wt% cobalt exchanged ferrierite catalyst (SrCo-FER) was prepared.

Example 10

Preparation of Ferrilite (IrCo-FER) with Iridium-Cobalt Ion Exchange

0.51% by weight of strontium and ions were carried out in the same manner as in Example 1 except that the ion exchange reaction was performed once using 0.0005 mol of iridium nitrate instead of lanthanum nitrate, and then once exchanged using 0.02 mol of cobalt acetate. 1.47 wt% cobalt exchanged ferrierite catalyst (IrCo-FER) was prepared.

Example 11

Preparation of Ferrilite Platinum-Cobalt Ion Exchanged (PtCo-FER)

0.62% by weight of platinum and 0.61% of an ion exchange reaction using a platinum nitrate instead of lanthanum nitrate, followed by one ion exchange using 0.02 mole of cobalt acetate, and A ferrilite catalyst (PtCo-FER) with 1.45% by weight of cobalt was prepared.

※ Catalytic Activity Evaluation Method ※

The catalysts obtained in Comparative Examples and Examples were made into pellets of 20/50 mesh, respectively, and then used in reaction experiments. 0.7 g of catalyst was charged to a 3/8 "stainless steel fixed bed reactor to test for denitrification. The concentrations of nitrogen oxide and methane before and after the reaction were measured by a thermal conductivity detector (Thermal Conductivity) attached to gas chromatography (Hewlett Packard 5890 Series II). Each conversion rate was measured by quantification using Detector, TCD).

In one embodiment of the present invention, the composition of the reaction gas used to test the nitrogen oxide removal ability is used a simulated exhaust gas of the gas turbine, the composition of the simulated exhaust gas is nitrogen monoxide: methane: oxygen = 1: 0.5 A volume ratio of ˜20: 10 to 100 is preferred, and 10% water is further added to test the durability of the catalyst to water.

The composition of the gas used in the present invention was 1,200 ppm of nitrogen monoxide (NO), 1,600 ppm of methane, 3.2% of oxygen, and helium (balance), wherein the total gas flow rate was 300 cm 3 / min, which is a gas hourly gas hourly (Gas hourly). Space Velocity (GHSV) 14,000.

In addition, 10% of water was added to the reaction gas while maintaining the same space velocity to test the durability of the prepared catalysts against water. All activity measurements carried out in the present invention were first pretreated at 600 ° C. for 2 hours using 79% helium and 21% oxygen at the same space velocity as the reaction conditions and then at each desired reaction temperature.

Comparative Examples 6-9 and Examples 12-16

In the nitrogen oxide removal activity of the Co-FER and PdCo-FER catalysts prepared in Comparative Examples 1 to 4 and Examples 1 to 5 measured through the above experiments, the effect of the ion exchange amount of cobalt and the durability against water The results reflecting the role of palladium in are shown in Table 1 and Table 2, respectively.

-Denitrification Activity of Co-FER Catalyst According to Cobalt Loading Amount Comparative example Used catalyst Co ion exchange amount (wt%) NOx removal rate (%) Reaction temperature (%) 300 350 400 450 500 550 600 6 Comparative Example 1 1.5 0 (0) 3.2 (0) 16.8 (0) 269 (0.5) 35.8 (6.9) 47.8 (12.9) 50.2 (14) 7 Comparative Example 2 3.6 5 (0) 23.7 (0) 83 (0) 88.2 (20.3) 69.5 (46.9) 46.8 (37.3) 27.1 (23.6) 8 Comparative Example 3 5.0 0 (0) 5.2 (0) 74.9 (0) 81.0 (18.4) 69.3 (42.6) 42.4 (24.9) 18.0 (10.1) 9 Comparative Example 4 6.6 3.3 (0) 24.1 (0) 69.8 (6) 80.2 (23.7) 60.7 (33.2) 34.9 (27.1) 19.5 (15.2)

(): When 10% of water is present.

-Denitrification Activity of PdCo-FER Catalyst Example Used catalyst Metal ion exchange amount (% by weight) NOx removal rate (%) Reaction temperature (%) 300 350 400 450 500 550 600 12 Example 1 Pd (0.31) Co (5.35) 5.5 (0) 35.5 (9.4) 87.1 (24.8) 96.3 (52.3) 97.6 (81.3) 88.5 (83.6) 64.9 (66.4) 13 Example 2 Pd (0.48) Co (2.54) 3.7 (0) 18.5 (4.4) 50.9 (15.1) 84.4 (35.6) 80.3 (50.5) 61.0 (38.7) 42.7 (30.0) 14 Example 3 Pd (0.45) Co (4.97) 0 (0) 20.7 (0) 75.1 (8.6) 82.5 (38.3) 77.2 (69.4) 58.4 (52.9) 34.5 (33.9) 15 Example 4 Pd (0.55) Co (1.57) 3.3 (0) 24.1 (0) 69.8 (6) 80.2 (23.7) 60.7 (33.2) 34.9 (27.1) 19.5 (15.2) 16 Example 5 Pd (0.64) Co (4.35) 0 (0) 28.7 (0) 72.9 (6.4) 89.8 (39.6) 80.2 (72.0) 59.3 (61.4) 42.7 (43.7)

(): When 10% of water is present.

Examples 17-22

After the nitrogen oxide removal ability of each of the cation exchange ferrierite catalysts obtained in Examples 6 to 11 was measured through the above experiments, the results are shown in Table 3 below.

-Denitrification Activity of Cationic FER Catalysts Example Used catalyst Metal ion exchange amount (% by weight) NOx removal rate (%) Reaction temperature (%) 300 350 400 450 500 550 600 17 Example 6 La (0.28) Co (1.52) 0 (0) 8.6 (0) 43.7 (0) 82.6 (7.8) 92.6 (13.9) 91.2 (49.0) 79.7 (44.2) 18 Example 7 La (0.13) Co (3.22) 0 (0) 3.3 (0) 68.9 (0) 90.1 (20.8) 84.0 (54.5) 58.6 (46.8) 34.5 (20.8) 19 Example 8 In (0.23) Co (1.59) 5.1 (0) 37 (0) 47.6 (0) 42.8 (13.6) 31 (29.5) 23.2 (9.4) 16.2 (6.5) 20 Example 9 Sr (0.31) Co (5.20) 0 (0) 19.9 (0) 67.8 (1.3) 87.2 (23.8) 72.2 (43.3) 46.1 (37.3) 26.9 (20.8) 21 Example 10 Ir (0.51) Co (1.47) 6.1 (0) 28.5 (0) 57.9 (0) 62.1 (4.8) 53.9 (10.3) 36 (10.6) 18.2 (11) 22 Example 11 Pt (0.62) Co (1.45) 0 (0) 10 (0) 41.1 (0) 68.2 (5.8) 69.1 (13.6) 36.2 (6.6) 13.9 (1.7)

(): When 10% of water is present.

Comparative Example 10

Among the catalysts, the nitrogen oxide removal activity of the catalysts having similar total metal substitution rates to each other, that is, the Co-FER, Pd-FER, and PdCo-FER catalysts prepared in Comparative Examples 3, 5, and 3, was measured. When it does not exist, and after carrying out under the conditions which water exists, it compared with the result, and is shown in following FIGS.

As shown in Tables 1 to 3 and FIGS. 1 and 2, it was found that the activity of the catalyst added with the second metal, especially palladium, was higher than that of the cobalt ion-exchanged catalyst alone on the ferrierite. In particular, as shown in Table 2, the denitrification activity of the catalyst loaded with 0.31% by weight of palladium and 5.35% by weight of cobalt showed 80% or more of activity at 500 to 550 ° C even if 10% of water was present in the exhaust gas 52% showed good denitrification activity. Therefore, the present invention was able to improve the serious activity degradation caused by water present in the exhaust gas which has been a problem in methane-SCR.

As described above, according to the present invention, in the removal of nitrogen oxides using saturated and unsaturated hydrocarbons having 1 to 4 carbon atoms, especially methane as a reducing agent, a cation exchange ferrierite catalyst having excellent durability against water Even when water is present in the reaction product as a combustion product, it is possible to achieve excellent nitrogen oxide removal efficiency.

Claims (9)

A reaction containing nitrogen oxide and 2 to 20% by weight of water, characterized in that ferrierite is exchanged sequentially or simultaneously with 0.1 to 4.5% by weight of palladium and 1.0 to 6.0% by weight of cobalt based on the total weight of the catalyst. A cation exchange ferrierite catalyst for removing nitrogen oxides in a gas by selective catalytic reduction (SCR). The nitrogen oxide in the reaction gas containing nitrogen oxide and water according to claim 1, wherein the catalyst is prepared according to a wet ion exchange method (WIE), a solid ion exchange method (SSIE), or a mixture thereof. Cationic ion exchange ferrierite catalyst for removal by selective catalytic reduction (SCR). delete The nitrogen oxide in the reaction gas containing nitrogen oxide and water according to claim 1, wherein the ferrierite is exchanged sequentially or simultaneously with 0.3 to 1.2% by weight of palladium and 2.5 to 4.5% by weight of cobalt. A cationic ion exchange ferrierite catalyst for removing by a selective catalytic reduction (SCR). A cation exchange phaselite catalyst in which ferrierite is exchanged for 0.1 to 4.5% by weight of a metal selected from the group consisting of palladium, platinum, lanthanum, iridium, indium and strontium and 1.0 to 6.0% by weight of cobalt based on the total weight of the catalyst. In the presence of a reaction gas containing nitrogen oxides and 2 to 20% by weight of water, saturated and unsaturated hydrocarbons having 1 to 4 carbon atoms as reducing agents, the reaction temperature of 200 to 800 ℃ and the space velocity per hour of 3,000 to 100,000 A method for removing nitrogen oxides in a reaction gas by selective catalytic reduction, characterized in that the reaction under the reaction conditions. The method of claim 5, wherein the reducing agent is methane. 6. The method of claim 6, wherein the weight ratio of the nitrogen oxide to the methane is 0.05 to 10, the method of removing the nitrogen oxide in the reaction gas by the selective catalytic reduction method. The method of claim 5, wherein the reaction temperature is 200 to 600 ° C. 6. The method of claim 5, wherein the reaction temperature is 400 to 600 ° C. 6.