KR20130094542A - Method of reducing nitrogen oxide using amine compound as reductant - Google Patents

Abstract

PURPOSE: A reduction method of nitrogen oxide effectively returns nitrogen oxide to nitrogen and presents excellent nitrogen oxide reduction efficiency. CONSTITUTION: A reduction method of nitrogen oxide comprises a step of injecting a reducing agent including an amine compound and exhaust gas including nitrogen oxide to a catalyst system. The catalyst system includes a carrier alumina (Ag/Al2O3) catalyst. The amine compound is selected one from a group of monoethanolamine, ethylamine and their combination. [Reference numerals] (AA) Example 1 (Monoethanolamine); (BB) Example 1 (Ethylamine); (CC) Comparative example 1 (Ethanol + Ammonia); (DD) Comparative example 2 (Ethanol); (EE) Comparative example 3 (Ammonia)

Description

METHOD OF REDUCING NITROGEN OXIDE USING AMINE COMPOUND AS REDUCTANT BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a method for reducing nitrogen oxides using an amine compound as a reducing agent.

There is interest in the development of eco-friendly automobile engines that are less energy-efficient due to global warming and higher oil prices and less CO ₂ emissions. The recently developed diesel engine is a fuel-efficient engine with low CO ₂ emissions, and research and development is currently underway in Europe and Korea.

However, the diesel engine has a problem that the emission of nitrogen oxides (NO _x ) and particulate matter (PM), which are harmful to the human body and the environment, is small although CO ₂ emissions are small. Nitrogen oxides are a major cause of smog and acid rain, and they are increasingly being regulated in developed countries and domestically, so they must be removed through the exhaust gas aftertreatment system. As the regulations for nitrogen oxides are strengthened as described above, there is a further demand for development of exhaust gas aftertreatment technology as well as engine improvement.

The exhaust gas temperature of a light-duty vehicle is 150 to 250 DEG C in a diesel engine, the heavy-duty vehicle is in a range of 200 to 350 DEG C, and the temperature of the exhaust gas is somewhat low (RG Gonzales, " Diesel Exhaust Emission System Temperature Test ", T & D Report 0851 -1816P, SDTDC, US Department of Agriculture, Dec. (2008)). Therefore, diesel engine exhaust aftertreatment technology requires a catalyst system capable of removing nitrogen oxides even at low temperatures.

Urea SCR (Selective Catalytic Reduction) technology and NOx occlusion-type catalyst technology (Lean NOx) have been used as a method to effectively remove nitrogen oxides emitted from diesel engines in order to overcome exhaust gas regulations that are now strictly domestically and internationally. Trap, LNT) have been developed. The urea / SCR technology is known to have the best performance at low temperatures among the currently developed technologies for removing nitrogen oxides by using element as a reducing agent and selectively reducing and removing nitrogen oxide by using zeolite as a catalyst. However, the urea / SCR technology has a low hydrothermal stability and has technical defects such as easily showing a decrease in catalytic activity due to SO 2 and hydrocarbons contained in the exhaust gas. Further, the element storage device is additionally installed in the vehicle, (AE El-Sharkawy, PD Kalantzis, MA Syed and DJ Snyder, SAE International Journal of Passenger Cars- Mechanical Systems, 2 (2009) 1042).

Storing catalyst technology (LNT) by storing the NO _x generated in a number of conditions, oxygen in exhaust gas (Lean condition), a technology that oxygen is removed by reduction of NO _x that was occluded in the low condition (Rich condition) low temperature and It has the advantage of high temperature performance and does not require the additional infrastructure required in urea / SCR systems. However, there is a disadvantage in that the noble metal catalyst is frequently used, the price is high, the operation of the engine is complicated, and it is weak in sulfur poisoning (H. Shinjoh, N. Takahashi, K. Yokoda and N. Sugiura, Appl. ) 189).

The HC / SCR technology, developed as a replacement for urea / SCR technology and LNT technology, removes nitrogen oxides using diesel used as a hydrocarbon or fuel from exhaust gas as a reducing agent. However, HC / SCR technology has a disadvantage in that it exhibits low activity at low temperatures compared with urea / SCR technology.

In order to increase the low-temperature activity of HC / SCR, alcohol hydrocarbons and oxygenated hydrocarbons are used as reducing agents (K. Shimizu, M. Tsuzuki, A. Satsuma, Appl. Catal. 2007) 80), diesel fuel and ethanol are simultaneously being used as a reducing agent (MK Kim, PS Kim, JH Baik, I.-S. Nam, BK Cho and SH Oh, Appl. (2011) 1). However, it still shows low activity at 250 ° C or below. Therefore, it is necessary to develop a reducing agent or a catalyst system exhibiting high nitrogen oxide removal efficiency even at a low temperature in order to be applied to practical commercial systems.

One embodiment of the present invention is to provide a method for reducing nitrogen oxides which exhibits excellent nitrogen oxide removal efficiency using an amine compound as a reducing agent.

One embodiment of the present invention is directed to a process for the production of nitrogen oxides comprising the step of injecting an exhaust gas comprising a reducing agent comprising an amine compound and a nitrogen oxide into a catalyst system comprising a silver supported alumina (Ag / Al ₂ O ₃ ) Provide mitigation methods.

The amine compound may be selected from the group consisting of monoethanolamine, ethylamine, and combinations thereof.

The mixing ratio (reducing agent / nitrogen oxide) of the reducing agent and the nitrogen oxide may be 0.5 to 2 in the temperature range of 150 to 500 ° C.

In one embodiment of the present invention, the catalyst is a multi-layer structure including a first catalyst layer and a second catalyst layer, the first catalyst layer includes the silver-supported alumina (Ag / Al ₂ O ₃ ) first catalyst, The second catalyst layer may include a second catalyst selected from the group consisting of Fe-ZSM5, Cu-ZSM5, MnFe / ZSM5, Cu-SSZ13, and combinations thereof.

Further, in another embodiment of the present invention, the catalyst may further include a third catalyst layer together with a first catalyst layer and a second catalyst layer, wherein a second catalyst layer is formed between the first catalyst layer and the third catalyst layer Layer structure. Wherein the first catalyst layer comprises a silver-supported alumina (Ag / Al ₂ O ₃ ) first catalyst, the second catalyst layer comprises a Fe-ZSM 5 second catalyst, and the third catalyst layer comprises a MnFe / ZSM 5 third catalyst .

When the catalyst includes the first catalyst layer, the second catalyst layer and the third catalyst layer, the volume ratio of the first catalyst, the second catalyst and the third catalyst may be 0.75: 0.25: 1 to 1: 0.25: 1. Further, the reducing agent may be injected in order to pass the first catalyst layer, the second catalyst layer and the third catalyst layer in order.

The content of Cu or Fe in the second catalyst of Cu-ZSM5, Cu-SSZ13 or Fe-ZSM5 is 2 to 4% by weight based on the total weight of the second catalyst. In the MnFe / ZSM5 second catalyst, Is 10 to 40% by weight based on the total weight of the second catalyst, and the Fe content may be 5 to 20% by weight based on the total weight of the second catalyst.

The reducing agent may further include ethanol, wherein the content of ethanol may be 13 to 26% by volume based on 100% by volume of the total reducing agent (i.e., the amine compound and ethanol).

The exhaust gas may comprise 2.5 to 10% by volume of water.

Other details of the embodiments of the present invention are included in the following detailed description.

The method for reducing nitrogen oxides according to one embodiment of the present invention is capable of effectively reducing nitrogen oxides to nitrogen at low temperatures, that is, increasing the low temperature activity and excelling in the reduction efficiency of nitrogen oxides.

FIG. 1A is a graph showing the nitrogen oxide conversion rate measured according to the processes of Examples 1 and 2 and Comparative Examples 1 to 3. FIG.
1B is a graph showing a conversion rate to nitrogen (N ₂ ) measured by the processes of Examples 1 and 2 and Comparative Examples 1 to 3.
FIG. 1C is a graph showing ammonia (NH ₃ ) production rates measured by the processes of Examples 1 and 2 and Comparative Example 2. FIG.
2 is a graph showing the conversion of nitrogen (N ₂ ) obtained by carrying out the processes of Examples 1, 3 and 4. FIG.
FIG. 3 is a graph showing the conversion of nitrogen (N ₂ ) obtained by carrying out the processes of Examples 1, 5 and 6. FIG.
4 is a graph showing the conversion of nitrogen (N ₂ ) obtained by performing the processes of Examples 1, 7, and 8 to the measurement of conversion.
5 is a graph showing the conversion rate measurement of nitrogen (N ₂ ) according to the steps of Examples 1, 9, and 10 and Comparative Example 4.
FIG. 6 is a graph showing the conversion of nitrogen (N ₂ ) measured by the processes of Examples 11 to 14. FIG.
7 is a graph showing the conversion of nitrogen (N ₂ ) obtained by performing the processes of Examples 15 to 16 and Reference Example 1. Fig.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.

One embodiment of the present invention is directed to a process for the production of nitrogen oxides comprising the step of injecting an exhaust gas comprising a reducing agent comprising an amine compound and a nitrogen oxide into a catalyst system comprising a silver supported alumina (Ag / Al ₂ O ₃ ) Provide mitigation methods.

The amine compound may be selected from the group consisting of monoethanolamine, ethylamine, and combinations thereof, and monoethanolamine is most preferable. In the supported alumina catalyst system system, when the amine compound is used as a reducing agent, it exhibits excellent reducing activity compared with the conventional reducing agent such as urea or ethanol. The amine compound has both hydrocarbon and nitrogen components and has the advantage of easily producing an intermediate that reduces nitrogen oxides.

Among the amine compounds, monoethanolamine is most preferred because of its excellent N ₂ selectivity, which is derived from isocyanate (-NCO) and oxime (-C (H) = NOH) in monoethanolamine This is because it is easy to produce an intermediate having excellent reactivity. In addition, the monoethanolamine is decomposed on the catalyst to produce hydrogen, where the hydrogen generated can serve to accelerate the SCR reaction on the silver supported alumina catalyst.

The reducing agent may further include ethanol. At this time, the content of ethanol may be 13 to 26% by volume based on the total volume of the reducing agent (the total amount of the amine compound and ethanol).

In the silver-supported aluminum catalyst system, the nitrogen oxide removal rate of the catalyst varies depending on the mixing ratio of the reducing agent and the nitrogen oxide, and the mixing ratio (reducing agent / nitrogen oxide) of the reducing agent and the nitrogen oxide is 0.5 to 2 (This mixing ratio is a ratio according to the concentration of the reducing agent / nitrogen oxide, so no unit, for example, 400 ppm of monoethanolamine and 400 ppm of nitrogen oxide), the mixing ratio of reducing agent / nitrogen oxide is 1).

More specifically, in the temperature range of 150 to 350 占 폚, the mixing ratio of reducing agent / nitrogen oxide is 1, and when the mixing ratio of reducing agent / nitrogen oxide is 2 in the temperature range of more than 350 占 폚 and 500 占 폚 or less, the nitrogen oxide removal rate is high. The mixing ratio of reducing agent / nitrogen oxide is lowered in the order of 1, 0.5, and 2 in the temperature range of 150 to 350 ° C, and in the temperature range of more than 350 ° C and 500 ° C or less, the reducing agent / The mixing ratio of nitrogen oxides is lowered in order of 2, 1, and 0.5.

As a result, when the mixing ratio of the reducing agent / nitrogen oxide is 2, the unreacted reducing agent deactivates the active point at a low temperature (200-350 ° C) and the activity decreases.

In one embodiment of the present invention, the nitrogen oxide removal rate varies depending on the concentration of water in the reaction gas, and when water is included in the exhaust gas, the nitrogen oxide removal efficiency becomes better. Therefore, in order to increase the nitrogen oxide removal rate, it is necessary to optimize the water concentration, and the appropriate water content in the exhaust gas may be 2.5 to 10% by volume. A more suitable water content may be from 2.5 to 5% by volume, and in this case it is more suitable since it exhibits high nitrogen oxide removal efficiency at 350 캜 or lower.

In the silver-supported alumina catalyst, the content of silver is suitably 2 to 6% by weight based on the total weight of the silver-supported alumina catalyst, and the alumina may be 94 to 98% by weight. In the case of the silver-supported alumina catalyst, the removal rate of nitrogen oxides according to the reaction temperature differs according to the content of Ag. When the Ag content is low, the removal rate of nitrogen oxide is high at a high temperature and the removal rate of nitrogen oxide is low at a low temperature when the Ag content is high. The Ag content may be varied within a range of 2 to 6% by weight depending on the application temperature of the composition.

In addition, the alumina used as the carrier in the silver-supported alumina catalyst is preferably? -Alumina. When γ-alumina is used as a carrier, the BET surface area may be broad and small silver particles may be distributed evenly on the alumina surface.

In one embodiment of the present invention, the catalyst is a multi-layer structure including a first catalyst layer and a second catalyst layer, wherein the first catalyst layer includes the silver-supported alumina (Ag / Al ₂ O ₃ ) first catalyst, The second catalyst layer may include a second catalyst selected from the group consisting of Fe-ZSM5, Cu-ZSM5, MnFe / ZSM5, Cu-SSZ13, and combinations thereof. The volume ratio of the first catalyst to the second catalyst may be from 1: 1 to 1: 2. When the volume ratio of the first catalyst and the second catalyst is within this range, it is possible to exhibit more excellent activity. If the first catalyst is excessive, the ammonia is not removed and the N2 activity is not increased. If the second catalyst content is increased, the monoethanolamine is not oxidized in the first catalyst and the second catalyst is poisoned, can do. When such a catalyst having a bilayer structure is used, superior nitrogen oxide removal activity can be obtained. The ZSM5 is aluminosilicate as one type of zeolite, a material known as _{Na n Al n Si 96-n} O 192 · 16H 2 O (0 <n <27), SSZ13 are a type of aluminosilicate zeolite, RN _a Na _{b Al 2.4 Si 33.6 O 72 ·} wH 2 O (1.4 <a <27, 0.7 <b <4.3, 1 <w <7, RN: N, N, N-1- trimethyl adamantyl ammonium agent, N, N, N-1-trimethyladamantammonium).

Further, in another embodiment of the present invention, the catalyst may further include a third catalyst layer together with a first catalyst layer and a second catalyst layer, wherein a second catalyst layer is formed between the first catalyst layer and the third catalyst layer Layer structure. Wherein the first catalyst layer comprises a silver-supported alumina (Ag / Al2O3) first catalyst, the second catalyst layer comprises a Fe-ZSM5 second catalyst, and the third catalyst layer comprises a MnFe / ZSM5 third catalyst have. When the catalyst having such a triple layer structure is used, the second catalyst layer is excellent in high temperature activity and the third catalyst layer is excellent in low temperature activity, so that the nitrogen oxide removal effect can be increased from low temperature to high temperature.

That is, in one embodiment of the present invention, the catalyst may have a double layer structure or a triple layer structure. Regardless of whether the catalyst has a double layer structure or a triple layer structure, the catalyst layer in which the shear, that is, the reducing agent and the exhaust gas mixture are first contacted is the silver-supported alumina first catalyst. The ammonia is removed to reduce nitrogen oxides to nitrogen Thereby maximizing the deNOx efficiency. That is, if the catalyst has a triple layer structure, a mixture of the reducing agent and the exhaust gas may be injected in order to pass through the first catalyst layer, the second catalyst layer and the third catalyst layer.

When the catalyst includes the first catalyst layer, the second catalyst layer and the third catalyst layer, the volume ratio of the first catalyst, the second catalyst and the third catalyst may be 0.75: 0.25: 1 to 1: 0.25: 1. When the volume ratio of the first catalyst, the second catalyst, and the third catalyst is within the above range, the catalyst may exhibit better activity at temperatures below 300 ° C.

The content of Cu or Fe in the second catalyst of the Cu-ZSM5, Cu-SSZ13 or Fe-ZSM5 is preferably 2 (preferably 2) or more based on the total weight of the second catalyst (i.e., the total weight of Cu-ZSM5, Cu- By weight based on the total weight of the second catalyst, and the content of Mn in the MnFe / ZSM5 second catalyst is 10 to 40% by weight based on the total weight of the second catalyst, and the Fe content is 5 to 20% %. &Lt; / RTI &gt; When the content of Cu, Fe, Mn or the like is included in the above range, the ammonia removal rate can be further improved. Also, the nitrogen oxide removal rate may vary depending on the catalyst used.

When the catalyst has a triple layer structure, since the most excellent nitrogen oxide removal effect, especially the same catalyst volume, is obtained, the total volume of the catalyst can be equal to the total volume of the bilayer structure, An excellent nitrogen oxide removal effect can be obtained without an excessive increase of nitrogen oxide.

Hereinafter, specific embodiments of the present invention will be described. However, the embodiments described below are only intended to illustrate or explain the present invention, and thus the present invention should not be limited thereto.

(Production Examples 1 to 7)

AgNO 3 solution was impregnated with γ-Al ₂ O ₃ (BET = 207 m ² / g) so that Ag contents carried on γ-Al ₂ O ₃ were 2, 4 and 6 wt%, respectively. Dried for 12 hours, and then calcined at 550 ° C for 5 hours to prepare an Ag / Al ₂ O ₃ catalyst (Production Examples 1, 2 and 3).

(BET = 360 m ² / g) or SSZ 13 (BET = 480 m ² / g) was added to a 0.01M concentration of Fe (NO ₃ ) ₃ .9H ₂ O or Cu (ZrO ₂ ) CH ₃ COO) ₂ .H ₂ O solution to make Fe or Cu content of about 3 wt%, and they were dried in an oven at 10 ° C for 12 hours and then calcined at 550 ° C for 5 hours (Production Examples 4, 5 and 6).

The MnFe / ZSM5 catalyst was prepared by impregnating ZSM5 with Mn (NO ₃ ) ₂ .6H ₂ O and Fe (NO ₃ ) ₃ .9H ₂ O solutions at the same time so that Mn and Fe contents were 30 and 10 wt% And then fired at 500 ° C for 5 hours while flowing oxygen at a concentration of 21% (Production Example 7).

(Example 1)

Into the catalyst _{(Ag / Al 2 O 3,} 4% by weight of Ag content) prepared in Preparative Example 2, the catalytic reaction device, prior to measuring the NOx removal rate, 2.5 vol% H ₂ O, 6 vol% O ₂ and And pretreated at a temperature of 550 DEG C for 2 hours under a mixed gas of residual He.

After the pretreatment, 400 ppm NO, 2.5 vol% H ₂ O, 6 vol% O ₂ and residual He were injected and 400 ppm NH ₂ (CH ₂ ) ₂ OH was injected as a reducing agent. At this time, the space velocity was 60,000 h ^-1 and the reaction was maintained at 150 ° C., 175 ° C., 200 ° C., 250 ° C., 300 ° C., 350 ° C., 400, , And the activity at each reaction temperature was measured. Further, the mixing ratio (MEA / NO _x ) of the monoethanolamine / nitrogen oxide was 1.

(Example 2)

400 ppm NH ₃ CH ₂ CH ₃ was injected as a reducing agent and the reaction temperature was changed to 180 ° C, 200 ° C, 220 ° C, 240 ° C, 275 ° C, 300 ° C, 350 ° C, 425 ° C and 500 ° C, The reaction was carried out in the same manner as in Example 1, except that the reaction was continued for 2 hours in the steady state.

(Comparative Example 1)

₂₀₀ ppm, 225 ppm, 250 ppm, ₃₀₀ ppm, 350 ppm, 400 ppm, 450 ppm, ₅₀₀ ppm, and 400 ppm of a mixture of C ₂ H ₅ OH and 400 ppm NH ₃ as a reducing agent. The reaction was carried out in the same manner as in Example 1, except that the reaction was continued at the reaction temperature for 2 hours while maintaining a steady state.

(Comparative Example 2)

400 ppm of C ₂ H ₅ OH was added as a reducing agent and the reaction temperature was changed to 200 ° C, 250 ° C, 275 ° C, 300 ° C, 350 ° C, 400 ° C, 450 ° C and 500 ° C, The reaction was carried out in the same manner as in Example 1 except that the reaction was carried out while maintaining a steady state during the reaction.

(Comparative Example 3)

By injecting 400ppm of NH ₃ as the reducing agent, and changing the reaction temperature to 159 ℃, 200 ℃, 250 ℃ , 275 ℃, 300 ℃, 350 ℃, 400 ℃, 450 ℃, 500 ℃, respectively, for 2 hours at the reaction temperature The reaction was carried out in the same manner as in Example 1 except that the reaction was carried out while maintaining a steady state during the reaction.

The concentration of adducts such as NH ₃ , NO, NO ₂ , N ₂ O, CO and CO ₂ produced after completion of the catalytic reaction according to Examples 1 to 2 and Comparative Examples 1 to 3 was measured by FT-IR FT-IR; Nicolet 6700). From this result, the ratio of the removed nitrogen oxide to the injected nitrogen oxide concentration, that is, the deNOx activity, that is, the NOx conversion% (NOx conversion%) was calculated and the results are shown in FIG.

As shown in Fig. 1A, in Examples 1 and 2 using monoethanolamine or ethylamine as the reducing agent, the best nitrogen oxide conversion (NOx conversion) was obtained. In the case of Comparative Example 3 using ammonia as a reducing agent, the nitrogen oxide conversion rate was the lowest, and it was found that the conversion of nitrogen oxide was superior to that of ethanol or ammonia, which is mainly used as a reducing agent in the HC / SCR reaction. When ammonia is injected as a reducing agent, it shows a negative conversion of nitrogen oxides at a temperature of 400 ° C or higher, which means that ammonia is oxidized to generate nitrogen oxides.

After the completion of the catalytic reaction according to Examples 1 and 2 and Comparative Examples 1 to 3, the gas (N ₂ ) produced by packing a packed column (molecular sieve 5 A) to analyze quantitatively nitrogen The amount of nitrogen produced was measured using chromatography (GC; HP 6890). From this result, the ratio of the nitrogen concentration generated to the reactant concentration including the injected nitrogen was calculated, and the conversion rate (%) of the reactant containing nitrogen to the nitrogen was shown in FIG.

The results shown in Fig. 1B also showed that the conversion of nitrogen oxides to nitrogen according to Examples 1 and 2 was the best.

The ammonia (NH3) content was measured using FT-IR (FT-IR; Nicolet 6700) after the catalytic reaction according to Examples 1 and 2 and Comparative Example 2. From the results, The conversion of ammonia in the reaction product containing nitrogen (%) results are shown in Fig. 1c, by calculating the ratio of ammonia produced to the concentration of reactant containing nitrogen. As shown in Fig. 1c, in Example 2 It is found that the conversion to nitrogen is low because ammonia is generated more than in the case of Example 1 using monoethanol.

(Example 3)

Catalytic reaction was carried out in the same manner as in Example 1 except that the catalyst (Ag / Al ₂ O ₃ , Ag content: 2% by weight) prepared in Preparation Example 1 was used.

(Example 4)

Catalytic reaction was carried out in the same manner as in Example 1 except that the catalyst (Ag / Al ₂ O ₃ , Ag content: 6 wt%) prepared in Preparation Example 3 was used.

After the catalytic reaction was completed according to Examples 3 and 4, the amount of nitrogen (N ₂ ) produced was measured using a gas chromatograph (GC: HP 6890) equipped with a packed column (molecular sieve 5A). From these results, the conversion of the injected nitrogen-containing reactant to nitrogen was calculated and the results are shown in FIG. For comparison, the results of Example 1 are also shown in Fig. As shown in FIG. 2, as the Ag content was increased from 2 to 6 wt%, the activity at high temperature of 300 ° C or higher was decreased, while the activity at low temperature of less than 300 ° C was increased. In addition, in Example 1 in which the Ag content was 4 wt%, excellent results were obtained at both low temperature and high temperature.

(Example 5)

The catalytic reaction was carried out in the same manner as in Example 1 except that the mixing ratio of monoethanolamine / nitrogen oxide (MEA / NOx) was changed to 0.5.

(Example 6)

The catalytic reaction was carried out in the same manner as in Example 1 except that the mixing ratio (MEA / NOx) of monoethanolamine / nitrogen oxide was changed to 2.

After the completion of the catalytic reaction according to Examples 5 and 6, the amount of nitrogen (N ₂ ) produced was measured using a gas chromatograph (GC: HP 6890) equipped with a packed column (molecular sieve 5A). From these results, the conversion of the injected nitrogen-containing reactant to nitrogen was calculated and the results are shown in FIG. For comparison, the results of Example 1 are also shown in Fig.

As shown in Fig. 3, when the ratio of MEA (monoethanolamine) / NOx was increased from 0.5 to 1, overall activity was increased in the temperature range of 200 to 500 占 폚. As the ratio of MEA / NOx increases from 1 to 2, it can be seen that the nitrogen conversion rate is increased at a temperature higher than 400 ° C.

(Example 7)

Except that 400 ppm NO, 0 volume% H ₂ O, 6 volume% O 2 and residual He were injected instead of 400 ppm NO, 2.5 volume% H ₂ O, 6 volume% O ₂ and residual He. The same catalytic reaction was carried out.

(Example 8)

400ppm NO, 2.5 vol% H ₂ O, 6% O ₂ by volume, and the remaining amount He instead, 400ppm NO, 10 vol% H ₂ O, 6% O ₂ by volume, and Catalyst reaction was carried out in the same manner as in Example 1 except that residual He was injected.

After the catalytic reaction was completed according to Examples 7 and 8, the amount of nitrogen (N ₂ ) produced was measured using a gas chromatograph (GC: HP 6890) equipped with a packed column (molecular sieve 5A). From these results, the conversion of the injected nitrogen-containing reactant to nitrogen was calculated and the results are shown in FIG. For comparison, the results of Example 1 are also shown in FIG. As shown in FIG. 4, when water was included in the experimental conditions, water activity was higher than 350 ° C. when water was contained. In addition, when the concentration of water was 2.5 vol.%, The highest activity was shown. When the concentration of water was increased to 10 vol.%, The activity tended to decrease somewhat.

(Example 9)

Catalyst reaction was carried out in the same manner as in Example 1 except that 600ppm of ethanol and 200ppm of monoethanolamine were mixed.

(Example 10)

Except that a mixed reducing agent of 700 ppm of ethanol and 100 ppm of monoethanolamine was injected into the reactor.

(Comparative Example 4)

Catalyst reaction was carried out in the same manner as in Example 1 except that 800 ppm of an ethanol reducing agent was injected.

The amount of nitrogen (N ₂ ) produced after completion of the catalytic reaction according to Examples 9 to 10 and Comparative Example 4 was measured using a GC (HP 6890) equipped with a packed column (molecular sieve 5A) Respectively. From these results, the conversion of the injected nitrogen-containing reactant to nitrogen was calculated and the results are shown in FIG. As shown in FIG. 5, when 800 ppm of ethanol at 250 ° C was used as a reducing agent, the conversion to nitrogen was 30%, but when 400 ppm of monoethanolamine was used, the conversion was 75%. In addition, when the concentration of monoethanolamine was reduced to 200 ppm and 600 ppm of ethanol was added, the conversion was 77%, the concentration of monoethanolamine was reduced to 100 ppm, and when 700 ppm of ethanol was added, the conversion was 71% . That is, it can be seen that the addition of ethanol at least to the amount of monoethanolamine used as a reducing agent can achieve a conversion to nitrogen of 70% or more.

(Example 11)

A catalyst composed of the first catalyst layer of the catalyst (Ag / Al ₂ O ₃ , Ag content: 4 wt%) prepared in Production Example 2 and the second catalyst layer of the catalyst (Fe-ZSM5) prepared in Production Example 4 : The volume ratio of the second catalyst layer = 1: 1) was used. In this case, the first catalyst layer was used as the shear catalyst, and the volume of the shear catalyst and the rear stage catalyst was the same. At this time, the space velocity of the reactor was 30,000 h -1.

(Example 12)

Except that the catalyst composed of the first catalyst layer of the catalyst (Ag / Al ₂ O ₃ , Ag content: 4% by weight) prepared in Production Example 2 and the second catalyst layer of the catalyst prepared in Production Example 5 (Cu-ZSM5) Was carried out in the same manner as in Example 1.

(Example 13)

Except that the catalyst composed of the first catalyst layer of the catalyst (Ag / Al ₂ O ₃ , Ag content: 4% by weight) prepared in Production Example 2 and the second catalyst layer of the catalyst prepared in Production Example 7 (MnFe / ZSM5) Was carried out in the same manner as in Example 1.

(Example 14)

Except that the catalyst composed of the first catalyst layer of the catalyst (Ag / Al ₂ O ₃ , Ag content: 4% by weight) prepared in Preparation Example 2 and the second catalyst layer of the catalyst prepared in Preparation Example 6 (Cu-SSZ13) Was carried out in the same manner as in Example 1.

The amount of nitrogen (N2) produced after completion of the catalytic reaction according to Examples 11 to 14 was measured using a gas chromatograph (GC: HP 6890) equipped with a packed column (molecular sieve 5A). From these results, the conversion of the injected reactant containing nitrogen into nitrogen was calculated and the results are shown in FIG. In Example 11, the conversion to nitrogen was 90% or more at 400 ° C or higher, and in Example 12, the nitrogen conversion was 90% or more at 300 ° C or more.

Further, in Example 14, the nitrogen conversion was high at 275 ° C or lower, and in Example 13, the highest activity was observed at temperatures lower than 375 ° C. From this result, it can be seen that the nitrogen conversion rate according to the reaction temperature can be optimized by adjusting the catalyst composition.

(Example 15)

A first catalyst layer of the catalyst (Ag / Al ₂ O ₃ , Ag content 4% by weight) prepared in Production Example 2, a second catalyst layer of the catalyst (Fe-ZSM5) prepared in Production Example 4, and a catalyst prepared in Production Example 7 (MnFe / ZSM5) were sequentially used in place of the first catalyst layer. At this time, the total space velocity was 30,000 h ^-1 . The volume ratio of the first catalyst layer, the second catalyst layer, and the third catalyst layer was 0.75: 0.25: 1.

(Example 16)

The catalytic reaction was carried out in the same manner as in Example 15 except that the volume ratio of the first catalyst layer, the second catalyst layer and the third catalyst layer was changed to 1: 0.25: 1.

(Reference Example 1)

Catalytic reactions were carried out in the same manner as in Example 15 except that the volume ratio of the first catalyst layer, the second catalyst layer and the third catalyst layer was changed to 1: 0.25: 0.75.

(GC) (HP 6890) equipped with a packed column (molecular sieve 5A) was used for the amount of nitrogen (N ₂ ) produced after completion of the catalytic reaction according to Examples 15 to 16 and Reference Example 1 Respectively. From these results, the conversion of the injected reactant containing nitrogen into nitrogen was calculated and the results are shown in FIG.

In the case of Examples 15 and 16 in which the volume ratios of the catalysts were 0.75: 0.25: 1 and 1: 0.25: 1, excellent nitrogen conversions were observed at 80% or more at a temperature of 200 ° C or more. In the case of Reference Example 1 in which the volume ratio of the catalyst was 1: 0.25: 0.75, the conversion to nitrogen was decreased at a temperature of 250 DEG C or lower. That is, when the volume of the MnFe / ZSM5 catalyst is decreased, the efficiency of removing ammonia produced at a low temperature is lowered, and consequently, the conversion of nitrogen oxide to nitrogen is lowered.

The present invention is not limited to the above embodiments, but may be manufactured in various forms, and a person skilled in the art to which the present invention pertains has another specific form without changing the technical spirit or essential features of the present invention. It will be appreciated that the present invention may be practiced as. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (11)

Injecting an exhaust gas containing a reducing agent containing an amine compound and a nitrogen oxide into a catalyst system containing a silver-supported alumina (Ag / Al ₂ O ₃ ) catalyst
Wherein the method comprises the steps of: The method of claim 1,
Said amine compound is selected from the group consisting of monoethanolamine, ethylamine and combinations thereof. The method of claim 1,
The mixing ratio (reducing agent / nitrogen oxide) of the reducing agent and the nitrogen oxide is 0.5 to 2 in the range of 150 to 500 ℃. The method of claim 1,
Wherein the content of silver in the silver-supported alumina catalyst is 2 to 6 wt% based on the total weight of the catalyst. The method of claim 1,
Wherein the catalyst has a multi-layer structure including a first catalyst layer and a second catalyst layer,
Wherein the first catalyst layer comprises the silver-supported alumina (Ag / Al ₂ O ₃ ) first catalyst,
The second catalyst layer is a method of reducing nitrogen oxides comprising a second catalyst selected from the group consisting of Fe-ZSM5, Cu-ZSM5, MnFe / ZSM5, Cu-SSZ13, and combinations thereof. The method of claim 1,
Wherein the catalyst has a multilayer structure including a first catalyst layer, a third catalyst layer, and a second catalyst layer positioned between the first and third catalyst layers,
The first catalyst layer includes a silver-supported alumina (Ag / Al ₂ O ₃ ) first catalyst,
Wherein the second catalyst layer comprises a Fe-ZSM5 second catalyst,
And the third catalyst layer comprises a MnFe / ZSM5 third catalyst. The method of claim 6, wherein
Wherein the volume ratio of the first catalyst, the second catalyst, and the third catalyst is 0.75: 0.25: 1 to 1: 0.25: 1. 5. The method of claim 4,
The content of Cu or Fe in the second catalyst of Cu-ZSM5, Cu-SSZ13 or Fe-ZSM5 is 2 to 4% by weight based on the total weight of the second catalyst,
In the MnFe / ZSM5 second catalyst, the content of Mn is 10 to 40% by weight based on the total weight of the second catalyst, and the content of Fe is 5 to 20% by weight of the total weight of the second catalyst. Way. The method of claim 1, wherein
Wherein the reducing agent further comprises ethanol, and the content of ethanol is 13 to 26% by volume based on 100% by volume of the total reducing agent. The method of claim 1,
Wherein the exhaust gas comprises 2.5 to 10% by volume of water. The method of claim 1,
Wherein the catalyst has a multilayer structure including a first catalyst layer, a third catalyst layer, and a second catalyst layer positioned between the first and third catalyst layers,
The first catalyst layer includes a silver-supported alumina (Ag / Al ₂ O ₃ ) first catalyst,
Wherein the second catalyst layer comprises a Fe-ZSM5 second catalyst,
The third catalyst layer comprises a MnFe / ZSM5 third catalyst,
Wherein the reducing agent is injected in order to pass through the first catalyst layer, the second catalyst layer and the third catalyst layer in order.

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