KR102020303B1 - Low Temperature De―NOx Catalyst for Selective Catalytic Reduction and Preparation Method Thereof - Google Patents

Abstract

The present invention relates to a low-temperature denitrification catalyst for selective catalytic reduction reaction and a method for producing the same, more particularly, excellent in removing nitrogen oxides in exhaust gas even at low operating temperatures, and the treated gas does not cause secondary environmental pollution. Low-temperature denitration catalyst for selective catalytic reduction reaction that can contribute to practical use by using commercial vanadium-based catalyst instead of manganese-based catalyst due to its strong poisoning resistance, which does not reduce nitrogen oxide removal efficiency even after long-term operation It is about.

Description

Low Temperature De-NOx Catalyst and Selective Method for Selective Catalytic Reduction

The present invention relates to a low temperature denitration catalyst for selective catalytic reduction reaction and a method for manufacturing the same, and more particularly, to a low temperature denitration catalyst for selective catalytic reduction reaction capable of efficiently decomposing and removing nitrogen oxides contained in exhaust gas at a low operating temperature. And to a method for producing the same.

Nitrogen oxides (NOx) are nitrogen dioxide, nitrogen dioxide and nitrous oxide, which are representative air pollutants that cause photochemical smog and acid rain as they are generated during the combustion process and discharged into the atmosphere from fixed sources such as power plants and various industrial boilers.

Among the technologies for removing nitrogen oxides, the most widely commercialized technologies are SCR (Selective Catalytic Reduction) method which reduces nitrogen oxides to harmless water and nitrogen on the catalyst by using ammonia as reducing agent, and high temperature range without using catalyst. There is a selective non-catalytic reduction (SNCR) method that converts nitrogen oxides into nitrogen and water vapor using only a reducing agent (typically ammonia).

The SCR method injects ammonia or hydrocarbon-reducing agent into the exhaust gas discharged from the fixed source, mixes the exhaust gas and the reducing agent, and passes the catalyst to reduce nitrogen oxides to water and oxygen to remove nitrogen oxides. Although it is very effective in removing nitrogen oxides, the denitrification effect may be very deteriorated in operation conditions outside the proper temperature range, for example, low load operation in which the temperature of exhaust gas is low.

Recently, as the quality of fossil fuels decreases and the applications of SCR catalysts are expanded, there is an increasing need to improve catalyst performance in a wide range of temperatures other than the main active temperature of SCR catalysts. On the other hand, although the general operating temperature range of the existing SCR process is operating at high temperatures between 300 and 400 ° C, the temperature of exhaust gas is significantly reduced to 150-250 ° C in the case of power plant dust collection or after the turbocharger. In this case, the activity of the catalyst is also reduced proportionally.

Problems that may occur in the application of the SCR catalyst in the low temperature region include not only the deactivation but also a side reaction caused by unreacted ammonia due to the deactivation. In the case of unreacted ammonia, the reaction bond with sulfur is very high, which causes ammonium sulfate (AS) and ammonium bisulfate (ABS) to cause aging of the catalytic reactor and the post equipment. The International Maritime Organization (IMO) enforces NOx emissions regulation through Tier III of air pollution prevention, and if the discharge conditions are not met, ships cannot be operated in the ECA (Emission Control Area) area. Accordingly, there is an increasing need for a catalyst having activity in a low temperature region in addition to vibration resistance, high strength, and high density characteristics.

In addition, the fuel used in ships is heavy oil with more than 3.5% of SO ₂ content, and it is difficult to treat related harmful gases due to the difficulty of using clean fuel. There is a problem of lower fuel consumption compared to existing cities. This disadvantage can be solved by mounting the denitrification catalyst module at the rear end, but the temperature is gradually lowered and changed to the low temperature area in the rear movement process of the hot pollutant gas of the engine, so it is installed at the front end compared to the rear end. For this reason, there is a need for the development of high-efficiency, high-functional SCR catalysts in the low temperature range and the development of technologies focused on various applications.

Accordingly, Korean Patent No. 1113380 discloses an ammonia SCR catalyst containing manganese, cerium and zeolite for selective reduction of nitrogen oxide at low temperature, and Korean Patent Publication No. 2015-0129852 discloses selective reduction of nitrogen oxide at low temperature. SCR catalyst using an octahedral molecular sieve comprising cerium oxide and manganese oxide is disclosed.

But. The SCR catalysts not only cause resistance to sulfur dioxide (SO ₂ ) or moisture (H ₂ O), but also cause secondary pollutant generation problems, such as generation of NO ₂ and N ₂ O by NH ₃ and NO oxidation. can do. Above all, due to the high content of manganese (Mn) there was a problem that is difficult to apply to the commercialization immediately.

Korean Registered Patent No. 1113380 (published: 2009.09.17) Korea Patent Publication No. 2015-0129852 (Published: 2015.11.20)

The main object of the present invention is to solve the above-mentioned problems, and can contribute to the practical use using commercial vanadium-based catalysts, not manganese-based catalysts, and at the same time, it is excellent in removing nitrogen oxides in exhaust gas even at low operating temperatures. The present invention provides a low-temperature denitration catalyst for selective catalytic reduction reaction, and a method for producing the same, wherein the gas does not cause secondary environmental pollution, and nitrogen oxide removal efficiency does not decrease even after long-term operation.

In order to achieve the above object, one embodiment of the present invention comprises the steps of (a) mixing a cerium precursor aqueous solution, a zirconium precursor aqueous solution and a vanadium precursor aqueous solution; (b) adjusting the pH of the mixture to obtain an aqueous solution of cerium-zirconium-vanadium; (c) mixing the catalyst support with the cerium-zirconium-vanadium aqueous solution, and supporting cerium, zirconium and vanadium on the catalyst support by ultrasonic synthesis or impregnation; And (d) provides a method for producing a low temperature denitration catalyst for a selective catalytic reduction reaction comprising the step of drying and calcining the supporting material.

In a preferred embodiment of the present invention, the pH adjustment of the step (b) may be characterized by adjusting the addition of an alkali agent so that the pH of the mixture is 8 to 10.

In a preferred embodiment of the present invention, the catalyst support may be characterized in that at least one member selected from the group consisting of titanium dioxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ) and glass fiber (glass fiber). .

In a preferred embodiment of the present invention, the ultrasonic synthesis method or impregnation method of step (c) may be characterized in that it is carried out at 30 ℃ ~ 70 ℃ for 6 hours to 10 hours.

In a preferred embodiment of the present invention, the low temperature denitration catalyst for the selective catalytic reduction reaction is 5 wt% to 35 wt% cerium oxide, 1 wt% to 15 wt% zirconium oxide, 0.5 wt% to 8 wt% vanadium oxide and the catalyst It may be characterized by containing 45 wt% to 80 wt% of the support.

Another embodiment of the present invention provides a low temperature denitration catalyst for selective catalytic reduction reaction, characterized in that vanadium oxide, cerium oxide and zirconium oxide are supported on a catalyst support.

In another preferred embodiment of the present invention, the catalyst support may be characterized in that at least one member selected from the group consisting of titanium dioxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ) and glass fiber (glass fiber). .

In another preferred embodiment of the present invention, the low temperature denitration catalyst for selective catalytic reduction reaction is 5 wt% to 30 wt% cerium oxide, 3 wt% to 15 wt% zirconium oxide, 0.5 wt% to 5 wt% vanadium oxide and the catalyst It may be characterized by containing 60 to 80 wt% of the support.

The low temperature denitrification catalyst for selective catalytic reduction according to the present invention has excellent efficiency of removing nitrogen oxides from exhaust gas even at low operating temperatures, and does not cause secondary environmental pollution and has long poisoning resistance. Even if the NOx removal efficiency is not lowered, there is an effect that can contribute to practical use by using a commercial vanadium catalyst instead of a manganese catalyst.

1 is a process chart of a method for producing a low temperature denitration catalyst for selective catalytic reduction according to the present invention.
2 is a graph showing the removal efficiency of the nitrogen oxides of Examples 1 to 6 and Comparative Examples 1 and 2 according to the reaction temperature.
3 is a TEM image of the denitration catalyst for selective catalytic reduction reaction, (a) is a TEM image of the denitration catalyst for catalytic reduction reaction prepared in Comparative Example 1, (b) is a catalytic reduction reaction prepared in Comparative Example 2 TEM image of the denitration catalyst, (c) is a TEM image of the denitration catalyst for catalytic reduction reaction prepared in Example 5.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

Throughout this specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding the other components unless otherwise stated.

The present invention in one aspect, (a) mixing a cerium precursor aqueous solution, zirconium precursor aqueous solution and vanadium precursor aqueous solution; (b) adjusting the pH of the mixture to obtain an aqueous solution of cerium-zirconium-vanadium; (c) mixing the catalyst support with the cerium-zirconium-vanadium aqueous solution, and supporting cerium, zirconium and vanadium on the catalyst support by ultrasonic synthesis or impregnation; And (d) relates to a method for producing a low temperature denitration catalyst for a selective catalytic reduction reaction comprising the step of drying and calcining the supporting material.

More specifically, the method for preparing a low temperature denitration catalyst for selective catalytic reduction reaction according to the present invention uses vanadium (V ₂ O ₅ ), which is a main component of a commercial catalyst, rather than manganese (Mn) based catalyst, which is a conventional low temperature catalyst. Vanadium By including cerium (CeO ₂ ) and zirconium (ZrO ₂ ) to compensate for the shortcomings of the catalyst, it has high efficiency of removing nitrogen oxides from exhaust gases even at low operating temperatures, and the treated gas does not cause secondary environmental pollution. Even if it is operated for a long time due to high corrosion resistance, it is possible to obtain the effect that nitrogen oxide removal efficiency does not decrease.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. 1 is a process chart of a method for producing a low temperature denitration catalyst for selective catalytic reduction according to the present invention.

First, in the step (a) according to the present invention, a cerium precursor aqueous solution, a zirconium precursor aqueous solution and a vanadium precursor aqueous solution are mixed to obtain a mixture.

The mixture is obtained by mixing an aqueous solution of a cerium precursor, an aqueous solution of a zirconium precursor, and an aqueous solution of a vanadium precursor in which cerium precursor, zirconium precursor and vanadium precursor are dissolved in demineralized water, respectively. At this time, the content of the demineralized water can be used without limitation as long as each precursor is a content that can be sufficiently dissolved, preferably can be dissolved by adding 0.5 to 10 parts by weight of each precursor with respect to 100 parts by weight of demineralized water.

The cerium precursor can be used without limitation as long as it is a compound commonly used in the field of denitrification catalyst production for selective catalytic reduction reaction, preferably cerium nitrate [Ce (NO ₃ ) ₃ ], cerium acetate [Ce (CH ₃ CO ₂ ) ₃ ], cerium oxalate [Ce ₂ (C ₂ O ₄ ) ₃ ], cerium oxide (CeO ₂ ), and the like.

The cerium precursor may be contained in an amount of 5 parts by weight to 100 parts by weight, preferably 20 parts by weight to 70 parts by weight, based on 100 parts by weight of the catalyst support described later. When the content of the cerium precursor is less than 5 parts by weight, the dispersion characteristics are increased, but the oxygen storage characteristics in the lattice may be reduced, which may cause problems such as denitrification efficiency, and when exceeding 100 parts by weight, particles on the surface of the catalyst support At the same time, there is a problem in that the activity is lowered due to the aggregation, the content of the catalyst support may be relatively insufficient, and thus the catalyst formability may be reduced, and the catalyst activity may be deteriorated due to the increase of slip.

In addition, the zirconium precursor can be used without limitation as long as it is a compound commonly used in the field of denitrification catalyst production for selective catalytic reduction reaction, preferably zirconium acetate [ZrO (C ₂ H ₃ O ₂ ) ₂ ], zirconium chloride [ZrO ( Cl ₂ )], zirconium nitrate [ZrO (NO ₃ ) ₂ ], zirconium oxychloride (ZrOCl ₂ ), and the like.

The content of the zirconium precursor may be contained in 3 parts by weight to 60 parts by weight, preferably 5 parts by weight to 55 parts by weight, based on 100 parts by weight of the catalyst support. If the content of the zirconium precursor is less than 3 parts by weight, a low specific surface area and a decrease in the suppression of the cohesion of cerium may cause a problem of lowering the denitrification efficiency, and at the same time, the catalyst stability may be lowered due to low thermal resistance. If it exceeds the weight part, the acid point of the catalyst may decrease due to the zirconium crystal phase formation.

Meanwhile, the vanadium precursor can be used without limitation as long as it is a compound commonly used in the field of denitrification catalyst production for selective catalytic reduction reaction, preferably ammonium metavanadate (NH ₄ VO ₃ ), vanadium oxytrichloride (VOCl ₃ ), Vanadium oxide (V ₂ O ₅ ) and the like can be used, more preferably ammonium metavanadate (NH ₄ VO ₃ ). The ammonium metavanadate (NH ₄ VO ₃ ) is environmentally friendly compared to other types of catalysts and becomes pyro vanadium pentoxide (V ₂ O ₅ ) when thermal decomposition, vanadium pentoxide not only catalyzed to reduce the nitrogen oxides in the exhaust gas, It has excellent resistance to sulfur oxides and acts as a catalyst to oxidize sulfur dioxide (SO ₂ ) to sulfur trioxide (SO ₃ ), which converts sulfur dioxide into sulfuric acid (H ₂ SO ₄ ) by combining with water vapor in the exhaust gas. It also has the effect of removing it.

When ammonium metavanadate is used as the vanadium precursor, since the solubility of ammonium metavanadate is very small, it is preferable to stir oxalic acid (oxalic acid) in an aqueous solution of ammonium metavanadate to increase the solubility.

The vanadium precursor may be contained in an amount of 0.1 parts by weight to 15 parts by weight, preferably 0.5 parts by weight to 10 parts by weight, based on 100 parts by weight of the catalyst support. If the content of the vanadium precursor is less than 0.1 parts by weight, the effect of removing nitrogen oxides may be insufficient. If the content of the vanadium precursor is greater than 15 parts by weight, aggregation of the powder may occur due to a high content and the efficiency may not be satisfactory compared to the increase in content. However, economic and environmental reasons are not desirable.

Next, step (b) according to the present invention adjusts the pH of the mixture of the cerium precursor solution, the zirconium precursor solution and the vanadium precursor solution to obtain a cerium-zirconium-vanadium solution.

The pH adjustment is to adjust the pH of the mixture to 8 to 10, preferably pH to 8 to 9 by adding an alkali agent to increase the binding force between the metals contained in the mixture, the alkali agent is sodium hydroxide (NaOH), Ammonia water (NH ₄ OH) or the like can be used.

If the pH of the adjusted mixture is less than 8, the electrical potential of the surface shows a positive charge on the surface, and as the repulsive force occurs in the bond between the metals, the same components, not the bond between the main catalyst and the promoter Agglomeration of particles may occur, resulting in a decrease in porosity and an increase in particle size, which may result in a decrease in specific surface area. When the mixture pH exceeds 10, the bonding strength between metals may not be increased compared to the amount of alkali agent added. Alkaline agents can disturb the acid point of the catalyst and cause inactivation, which requires a complete washing process.

In the pH-adjusted solution of cerium-zirconium-vanadium, the cerium precursor and the zirconium precursor are transition metals, and the number of electrons occupying an electron orbit therein is incompletely lost, resulting in a cation state, and thus the vanadium precursor and the compound. Formation improves the activation of the selective catalytic reduction reaction at low temperatures. In addition, cerium precursors can enhance the oxygen storage capacity and resistance to SO ₂ , and zirconium precursors have a large specific surface area, excellent mechanical strength and thermal stability, and resistance to SO ₂ . Compared to the impact resistance, heat resistance and corrosion resistance, and easily reacts with oxygen to form an oxide passivation protective film, the low temperature denitration catalyst according to the present invention is not oxidized well and is stable against alkali, sulfuric acid, hydrochloric acid and the like.

Thereafter, step (c) according to the present invention mixes the catalyst support with the cerium-zirconium-vanadium solution, and supports cerium, zirconium and vanadium on the catalyst support by ultrasonic synthesis or impregnation.

The catalyst support can be used without limitation as long as it is a catalyst support component that can be used in the denitrification process, preferably in the group consisting of titanium dioxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ) and glass fiber (glass fiber) It may be one or more selected.

The catalyst support may be mixed with a pH-adjusted solution of cerium-zirconium-vanadium or dissolved in demineralized water and then mixed with a pH-adjusted solution of cerium-zirconium-vanadium.

When dissolving the catalyst support in the demineralized water, the catalyst support material can be used without limitation as long as the content of the catalyst support material can be sufficiently dissolved. Preferably, the catalyst support may be dissolved by adding 1 part by weight to 50 parts by weight of the catalyst support. .

As described above, when the catalyst support is mixed with an aqueous solution of cerium-zirconium-vanadium, ultrasonic synthesis or impregnation is performed at 30 ° C. to 70 ° C. for 6 hours to 10 hours.

If the ultrasonic synthesis or impregnation method is performed at 30 ° C. or less than 6 hours, the catalyst support material, cerium, zirconium and vanadium is not sufficiently supported on the catalyst support, and if vanadium is exceeded at 70 ° C. or 6 hours, Due to the grain growth of the particles, the catalytic bond with the catalyst support may fall, and the specific surface area may be lowered, resulting in a problem that the catalyst efficiency is finally lowered.

In the ultrasonic synthesis method, as the ultrasonic waves are provided in the cerium-zirconium-vanadium aqueous solution in which the catalyst support is mixed, the metal salts may be arranged and aligned according to the ultrasonic energy so that the metal salts may be more uniformly dispersed on the catalyst support. The ultrasonic providing environment may be appropriately adjusted according to the size of the aqueous solution to be prepared and the concentration of each metal salt.

In addition, the impregnation method can be supported on the catalyst support uniformly without agglomeration of the metal salts as the solution of the cerium-zirconium-vanadium solution mixed with the catalyst support is supported on the catalyst support under agitation. It may be appropriately adjusted according to the size of the aqueous solution to be prepared and the concentration of each metal salt.

Thereafter, the supporting material generated by the ultrasonic synthesis or impregnation may be filtered by a method such as centrifugation or membrane separation, and then repeatedly washed with distilled water or alcohol.

Next, step (d) according to the present invention to dry and calcined the support to prepare a low-temperature denitration catalyst for selective catalytic reduction reaction.

The supporting material obtained by the ultrasonic synthesis or impregnation method is prepared by removing moisture in the supporting material by using a rotary vacuum evaporator and the like, and remaining moisture contained in the micropores in the supporting material by drying sufficiently with a dryer or the like.

When the drying temperature is too low or the drying time is too short, the drying is not completely dried to contain water in the catalyst micropores, the activity may be reduced, and if the drying temperature is too high or the drying time is too long, sintering The activity of the catalyst may be reduced due to the development, and the supporting material may be dried at 60 ° C. to 100 ° C. for 2 hours to 24 hours.

The dried product is dried to prepare a low temperature denitration catalyst for selective catalytic reduction reaction through a calcination process to control the size and dispersion of the active ingredient through heat treatment. The calcination may be performed at 300 ° C. to 600 ° C. for 1 hour to 6 hours, considering the selective catalytic reduction ability of the catalyst.

When the firing condition is less than 300 ℃ or less than 1 hour, the material used as a precursor is not properly removed, and the low temperature denitration catalyst particles and pores for selective catalytic reduction reaction may be unevenly distributed, thereby reducing the removal efficiency of nitrogen oxides. When the temperature exceeds 600 ° C or 6 hours, the durability of the catalyst active material and the material used as the catalyst support decreases the durability, or the specific surface area decreases due to the phase transition of the catalyst support. As the catalyst components are not dissolved in the lattice and form a crystal phase, the removal efficiency of the nitrogen oxides may be lowered.

Such a firing process may be performed in various types of furnaces, such as a tube-type furnace, a convection furnace, a grate furnace, and the like, and are not particularly limited.

The low temperature denitrification catalyst for selective catalytic reduction reaction prepared as described above has vanadium, cerium and zirconium supported on the catalyst support to remove nitrogen oxides contained in the exhaust gas in the SCR process at 300 ° C. or less, preferably 150 ° C. It becomes stable at low temperature of -250 degreeC, More preferably, 150 degreeC-200 degreeC.

In another aspect, the present invention relates to a low temperature denitration catalyst for selective catalytic reduction reaction, characterized in that vanadium oxide, cerium oxide and zirconium oxide are supported on a catalyst support.

The catalyst support can be used without limitation as long as it is a catalyst support component that can be used in the denitrification process, preferably in the group consisting of titanium dioxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ) and glass fiber (glass fiber) It may be one or more selected.

The low temperature denitrification catalyst for selective catalytic reduction according to the present invention is based on the total weight of the low temperature denitrification catalyst, cerium oxide 5 wt% to 35 wt%, zirconium oxide 1 wt% to 15 wt%, vanadium oxide 0.5 wt% to 8 wt% And 45 wt% to 80 wt% of the catalyst support, preferably 10 wt% to 25 wt% of cerium oxide, 5 wt% to 12 wt% of zirconium oxide and 2 wt% to 6 wt% of vanadium oxide, and catalyst support 60 wt% to 80 wt%.

The low temperature denitrification catalyst for selective catalytic reduction reaction of the composition ratio is excellent in removing the nitrogen oxides even at low temperature operating conditions, and can reduce the cost and energy shortening of the catalyst by high temperature operation as well as reducing the cost of energy saving. Excellent resistance to SO ₂ can keep the activity of the catalyst high during operation.

In addition, the low temperature denitration catalyst for the selective catalytic reduction reaction may be 45 wt% to 80 wt%, preferably 60 wt% to 80 wt% of the catalyst support, based on the total weight of the low temperature denitration catalyst. If the content of the catalyst support is out of the above range, the amount of supported catalyst active material may be insufficient, and the active material may not be uniformly dispersed on the surface of the catalyst support due to the high content. This leads to an increase in the oxidative power due to an excess of active substance, which oxidizes ammonia, a reducing agent, which leads to a deterioration of nitrogen oxide removal performance, and oxidizes SO ₂ to SO ₃ to cause side reactions such as ammonium sulfate (NH ₄ HSO ₄ ). Can cause.

The low temperature denitrification catalyst for selective catalytic reduction according to the present invention is a structure such as a metal plate, a metal fiber, a ceramic filter, a honeycomb, an extrusion process or a colloid in a particulate or monolith form with a small amount of binder. It can be prepared and used in various forms, such as plates, pellets.

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

< Example  1>

7 g of cerium nitrate [Ce (NO ₃ ) ₃ ] and 2.2 g of zirconium nitrate [ZrO (NO ₃ ) ₂ ] were respectively mixed with 100 g of distilled water, and each precursor aqueous solution was mixed with stirring to prepare a cerium-zirconium aqueous solution. . Next, 2 g of ammonium metavanadate (AMV) was mixed with 50 g of an aqueous solution of oxalic acid, and sufficiently dissolved. The aqueous solution of cerium-zirconium was previously mixed with the aqueous solution of ammonium metavanadate, stirred for 5 hours, and then sodium hydroxide (NaOH) was added thereto and the pH value of the mixture was maintained at 9 to obtain an aqueous solution of cerium-zirconium-vanadium. It was. 20 g of titanium dioxide was stirred and mixed with 100 g of distilled water for 2 hours, and then a previously prepared aqueous solution of cerium-zirconium-vanadium was added, and the mixture was ultrasonically synthesized at 30 ° C. for 6 hours. Thereafter, the obtained support was first dried at 70 ° C. for 12 hours in a drier, secondly dried at 100 ° C. for 8 hours, and after drying, calcined in an oven at 400 ° C. for 2 hours to form a low temperature for selective catalytic reduction reaction. A denitration catalyst was prepared.

< Example  2 to 6>

Content conditions for Examples 2 to 6 are shown in Table 1, except that each manufacturing method was carried out in the same manner as in Example 1 to prepare a denitration catalyst for selective catalytic reduction reaction.

division Cerium Nitrate Content
(g) Zirconium Nitrate Content
(g) AMV content
(g) Titanium dioxide content
(g) Example 1 7 2.2 2 20 Example 2 7 3.5 2 20 Example 3 7 5.2 2 20 Example 4 7 10 2 20 Example 5 13 10 2 20 Example 6 20 10 2 20

< Comparative example  1>

13 g of cerium nitrate [Ce (NO ₃ ) ₃ ] was mixed with 100 g of distilled water, and then stirred and mixed to prepare an aqueous cerium solution. Next, 2 g of ammonium metavanadate (AMV) was mixed with 50 g of an aqueous solution of oxalic acid, and sufficiently dissolved. The aqueous solution of cerium was previously mixed with the aqueous solution of ammonium metavanadate, stirred for 5 hours, and then sodium hydroxide (NaOH) was added thereto, and the pH value of the mixture was maintained at 9 to obtain an aqueous solution of cerium-vanadium. 20 g of titanium dioxide was stirred and mixed with 100 g of distilled water for 2 hours, and then a cerium-vanadium aqueous solution prepared above was added thereto, and the mixture was ultrasonically synthesized at 30 ° C. for 6 hours. Thereafter, the obtained support was first dried at 70 ° C. for 12 hours in a drier, secondly dried at 100 ° C. for 8 hours, and after drying, calcined in an oven at 400 ° C. for 2 hours to form a low temperature for selective catalytic reduction reaction. A denitration catalyst was prepared.

< Comparative example  2>

2.2 g of ammonium metavanadate (AMV) and 5 g of ammonium metatungstate (AMT) were dissolved in 100 g of distilled water, and then mixed to obtain an vanadium-tungsten aqueous solution. Next, the titanium dioxide aqueous solution dissolved 20 g of titanium dioxide in 100 g of distilled water. The vanadium-tungsten aqueous solution was mixed with the titanium dioxide aqueous solution and mixed for 5 hours to impregnate the catalytically active material under stirring. The obtained impregnation was first dried at 70 ° C. for 12 hours in a drier, and then secondly dried at 110 ° C. for 9 hours, and after drying, calcined in an oven at 400 ° C. for 3 hours for selective catalytic reduction reaction. A low temperature denitration catalyst was prepared.

[ Experimental Example  1]: low temperature for selective catalytic reduction Denitration catalyst  Ingredient measurement

XRF (X-ray fluorescence, Zetium, PAN 'alytical to measure the components of the denitration catalyst for selective catalytic reduction reaction prepared in Examples 1 to 6 are shown in Table 2.

division V ₂ O ₅ content
(wt%) CeO ₂ content
(wt%) ZrO ₂ content
(wt%) TiO ₂ content
(wt%) Other content
(wt%) Example 1 5.05 10.94 2.93 78.44 2.64 Example 2 4.95 10.38 5.28 76.88 2.51 Example 3 5.09 12.11 11.45 68.86 2.49 Example 4 5.18 12.49 11.67 67.92 2.746 Example 5 5.20 22.08 10.03 63.13 2.54 Example 6 4.89 32.41 11.24 50.18 1.28

As shown in Table 2, it could be seen that the results of analysis for different amounts of the synthesis were shown during synthesis. The other material is WO ₃ , Al ₂ O ₃ , SiO _2, etc. It is understood that the residue present in the measuring equipment.

[ Experimental Example  2]: low temperature for selective catalytic reduction reaction Denitration catalyst Denitrification  Measure

The NOx conversion reaction test equipment is equipped with a catalyst reaction part equipped with a catalyst, a heater for controlling the temperature of the catalyst reaction part, a pre-heater for preheating the injection gas, a temperature control panel for controlling the temperature and the amount of injection gas, and MFC (Mass). Flow Controller), Water Pump, etc. The temperature of the reactor was controlled in the range of 150 ℃ to 450 ℃, the catalyst to be analyzed was prepared as a powder catalyst, the catalysts prepared in Example 1 and Comparative Examples 1 and 2 are classified only 200 ㎛ size through grinding and sieving Was applied. Based on the criteria set forth in the VGB Guideline, which has been used as a criterion for denitrification catalytic performance in Europe, Japan, and the United States since 2005, the evaluation was conducted at 20,000 g / h of surface velocity (SV). The gas supplied to the reactor flowed the total amount of gas at a total flow rate of 500 sccm. NO gas (1% mol / mol) flowed 300 ppm (v / v) quantitatively, NH ₃ gas flowed to 300 ppm (v / v), and SO ₂ gas flowed to 500 ppm (v / v). . The concentration of 0 ₂ (1% mol / mol) was maintained at 5% (v / v) and the total flow was maintained at N ₂ (high purity liquefied nitrogen). In order to perform the accurate activity experiment, the reaction experiment was performed after stabilization for a certain time under the corresponding reaction conditions, and the reaction gas except O ₂ was analyzed using a CLD analyzer (Chemi-luminescence detector, T200H, Teledyne). O ₂ gas was analyzed using an O ₂ analyzer (OXITEC-5000, ENOTEC). After the measurement through the change in the NOx concentration of the gas outlet passed through the gas inlet and the catalytic reaction unit through the analysis equipment, the NOx removal efficiency is calculated through the following equation is shown in FIG.

[expression]

NO _x conversion (%) = 100 × ((inlet-outlet NO _x concentration) / inlet NO _x concentration)

As shown in FIG. 2, the catalysts of Examples 1 to 6 were superior to the catalysts of Comparative Examples 1 and 2 in the denitrification performance in the low temperature region of 150 ° C. to 250 ° C., and the catalysts of Example 5 were different from each other. The denitrification performance was much better than that of. This adds ZrO ₂ to make the vanadium species more active against NO oxidation, while at the same time reducing the charge on the surface and creating a double reduction reaction (V ₄ ⁺ + Zr ₄ ⁺ ↔ V ₅ ⁺ + Zr ₃ ⁺ , Ce ₄ ⁺ + Zr ₃ ⁺ ↔ Ce ₃ ⁺ + Zr ₄ ⁺ ) to increase the reaction activity and increase the denitrification efficiency by promoting the catalytic performance in the low temperature region by inducing more vanadium species on the surface. It can be seen that the performance is improved.

[ Experimental Example  3]: low temperature for selective catalytic reduction reaction Denitration catalyst Granular  analysis

The particle shape of the denitrification catalyst for selective catalytic reduction reaction prepared in Example 5 and Comparative Example 1 was measured by TEM (Field Emission Transmission Electron Microscope, JEM-2100F, JEOL).

As shown in FIG. 3, in the case of the catalyst prepared in Comparative Example 1 [FIG. 2 (a)], agglomeration of the catalyst particles appeared, whereas in the case of the catalyst prepared in Example 5 [FIG. In addition to the inhibition of growth it was confirmed that the dispersibility is improved.

[ Experimental Example  4]: low temperature for selective catalytic reduction Denitration catalyst Specific surface area  Measure

The catalyst is a surface reaction, and the specific surface area of the catalyst is directly related to the denitrification efficiency. In general, as the specific surface area increases, the dispersibility of the active ingredient is improved, and the increase in the active point is directly related to the high properties. Accordingly, the specific surface area (BET), pore volume, pore size and particle size of the denitration catalyst for selective catalytic reduction reaction prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were used. Was measured through ASAP 2010 (Micrometritics Co., USA) and shown in Table 3.

division BET
(m ² / g) pore volume (m ² g ^-1 ) Pore size
(nm) Particle size
(nm) Example 1 82.96 0.24 11.08 72.84 Example 2 95.59 0.27 10.89 62.76 Example 3 108.42 0.25 8.82 55.23 Example 4 139.32 0.26 6.93 43.06 Example 5 113.87 0.25 8.17 52.69 Example 6 120.53 0.26 7.85 48.54 Comparative Example 1 60.17 0.18 12.01 99.71 Comparative Example 2 81.29 0.27 11.18 73.80

As shown in Table 3, the catalysts of Examples 1 to 6 were found to have a larger specific surface area than the catalysts of Comparative Examples 1 and 2.

All simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (8)

(a) mixing Cerium precursor aqueous solution, zirconium precursor aqueous solution and vanadium precursor aqueous solution to obtain mixture 1;
(b) adjusting the pH of the mixture 1 to obtain a cerium-zirconium-vanadium aqueous solution;
(c) mixing the catalyst support with the aqueous solution of cerium-zirconium-vanadium to obtain mixture 2, providing ultrasonic wave to the mixture 2, and impregnating a support having cerium oxide, zirconium oxide, and vanadium oxide supported on the catalyst support. Obtaining; And
(d) drying and firing the support;
Adjusting the pH of step (b) is adjusted by adding an alkali agent so that the pH of the mixture 1 is 8 to 10,
The mixture 2 contains 5 to 100 parts by weight of the cerium precursor, 3 to 60 parts by weight of the zirconium precursor, and 0.1 to 15 parts by weight of the vanadium precursor with respect to 100 parts by weight of the catalyst support. Method for producing low temperature denitration catalyst.
The method of claim 1,
The alkaline agent is a sodium hydroxide (NaOH) or ammonia water (NH ₄ OH) characterized in that the method for producing a low temperature denitration catalyst for selective catalytic reduction reaction.
The method of claim 1,
The catalyst support is a method for producing a low temperature denitration catalyst for selective catalytic reduction reaction, characterized in that at least one selected from the group consisting of titanium dioxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ) and glass fiber (glass fiber). .
The method of claim 1,
The step (c) is a method for producing a low temperature denitration catalyst for selective catalytic reduction, characterized in that carried out for 30 to 70 ℃ for 6 hours to 10 hours.
The method of claim 1,
The low temperature denitrification catalyst for the selective catalytic reduction reaction includes 5 wt% to 35 wt% of cerium oxide, 1 wt% to 15 wt% of zirconium oxide, 0.5 wt% to 8 wt% of vanadium oxide, and 45 wt% to 80 wt% of the catalyst support. A method for producing a low temperature denitration catalyst for selective catalytic reduction reaction, characterized in that it contains.
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