KR102051857B1 - High performance nitrogen oxide reduction catalyst and method for producing the same - Google Patents

Abstract

In accordance with a preferred embodiment of the present invention, the high-performance nitrogen oxide reduction catalyst is a catalyst for reducing nitrogen oxides (NOx) in exhaust gas, in which ruthenium and iridium are supported on a support and selected from the group consisting of barium, potassium and cerium. It is characterized in that one species is further supported. By using the high performance nitrogen oxide reduction catalyst and the production method thereof according to the present invention, there is an advantage that the removal efficiency of NOx present in the exhaust gas at any temperature can be improved. In addition, there is an economic advantage because it does not need to introduce a separate reducing agent (urea) to remove the NOx present in the exhaust gas. In addition, there is an economical advantage because the supply of urea (reducing agent) is not necessary.

Description

High performance nitrogen oxide reduction catalyst and method for producing the same

The present invention relates to an Ir-based deNOx catalyst having improved NOx reduction rate and a method for producing the same, and more particularly, to a catalyst capable of removing NOx using CO present in exhaust gas.

Nitrogen oxides are mainly generated from mobile sources such as automobiles, and fixed sources such as industrial and power generation facilities, and have a great influence on the health and living environment of animals and plants. Nitrogen oxides exist in the form of NO, NO ₂ , N ₂ O, N ₂ O _4, etc. The biggest damage is related to the production of photochemical smog, which reacts with hydrocarbons in the presence of sunlight to produce photochemical oxides. In addition, it is estimated that about 40% of acid rain is caused by nitric acid because it is converted into nitric acid and nitrate which cause acid rain as well as visibility impairment and greenhouse effect. In addition, since hemoglobin has a strong adsorption performance of 20,000 times as much as O ₂ , it is known as a substance that can cause serious harm when the concentration is increased, and efforts to reduce it are urgently required.

Nitrogen oxides continue to increase, and the NOx emission rate by fuel is 7% Gas, 64% Oil and 29% Coal. The NOx emission rate by source is 49% in automobiles, 30% in industrial plants, and power plants. It is generated by 15% and 6% of heating.

Nitrogen oxides are discharged mainly at about 5% fuel NOx due to the combustion of nitrogenous components in fuel oil and prompt NOx generated near the flame surface in the presence of hydrocarbons. Thermal NOx generated during the combustion of fuel oil is taken up.

In order to reduce the emission of nitrogen oxide which is the main cause of urban air pollution, many countries are legally regulated. In Japan, the new large-capacity gas, oil and coal-fired power plants have regulations of 60, 130 and 200 ppm, respectively. However, to achieve atmospheric NOx concentrations regulated by local governments, power plants operate below 15, 30, and 60 ppm, well below the regulation, and gas turbines operate below 5 ppm. European limits are 30-50, 55-75 and 50-100 ppm for power plants and 25 ppm for gas turbines. In order to satisfy these regulations, methods for reducing nitrogen oxides are needed. Among them, the pretreatment technique using the combustion method includes reducing the amount of excess air, cooling the combustion section, lowering the air preheating temperature, recirculating the exhaust gas, and improving the structure of the burner and the combustion chamber. However, since these methods are not effective due to low NOx reduction efficiency, introduction of a post-treatment device is essential to effectively control them. In addition, the wet method, such as absorbing water, hydroxide or carbonate solution, sulfuric acid, etc., has good efficiency. However, when treating a large amount of gas, a huge amount of absorbent is required. The problem arises. Even in the dry method, a method using an adsorbent such as molecular sieve or activated carbon is difficult to apply when the amount of nitrogen oxide to be adsorbed is increased by a method used when a small amount of nitrogen oxide is contained in the flue gas. have.

For this reason, current techniques for NOx removal from most combustion gases currently utilize post-combustion treatment of hot flue gases with Selective Catalytic Reduction (SCR). The selective catalytic reduction process utilizes a catalyst bed or system to treat the flue gas stream for selective conversion (reduction) of NOx to N ₂ . SCR processes usually use ammonia or urea as reactants injected into the flue gas stream upstream prior to contact with the catalyst. In commercial applications, SCR systems can typically achieve NOx removal rates above 60%.

In the case of commonly used SCR catalysts, the urea solution is thermally decomposed when the urea solution is injected into a dosing module disposed at the front end in order to maintain the NOx purification performance at a predetermined level or higher. The ammonia (NH3) generated by hydrolysis through the material is occluded, and the ammonia and NOx stored therein can be reacted and purified.

On the other hand, in order to supply liquid urea to the catalyst, it is necessary to have a system, and additional space such as a container and an injection device for storing liquid urea requires a large space and economical because additional costs are required. There are disadvantageous aspects. In addition, the conventional liquid urea system has a problem in that the urea does not vaporize and is produced as solid ammonium when the exhaust gas temperature is sprayed at a temperature of 200 ° C. or less because the liquid urea system must inject liquid and vaporize the urea by the heat from the exhaust gas. come.

In addition, the SCR catalyst has a characteristic of increasing corrosiveness at 70 ° C or higher. Therefore, at the end of the vehicle and the system, the urea is recovered to the urea tank, which is called an after run.

When the selective catalytic reduction (SCR) system is operating normally, the urea is moved to the urea injection nozzle via the urea tank, the supply module, and is recovered in the reverse order when the after run is operated. When the inlet portion of the urea injection nozzle is heated by exhaust temperature to reach a temperature (71-75 ° C.) favorable for urea crystallization, and the after run is operated to maintain the inlet of the urea injection nozzle 100% open, the urea injection Crystallized urea is generated at the inlet of the nozzle, which may cause clogging of the urea injection nozzle.

That is, in the after-run operation, the inlet of the urea injection nozzle should be open, but the urea residue may crystallize and block the inlet of the urea injection nozzle.

In particular, when the reverse flow of the urea from the urea tank in winter, the frozen urea blocks the flow in the line to damage the selective catalytic reduction system, so the nitrogen oxides are removed without introducing urea (reducing agent) as in the present invention. There is a need for the development of catalysts that can.

KR 10-2017-0009150 A KR 10-2008-0025142 A KR 10-0665606 B1 KR 10-1438630 B1

The present invention has been proposed to solve the above problems, and the object of the present invention is to provide a deNOx catalyst capable of removing NOx at low and high temperatures without introducing a reducing agent by using carbon monoxide (CO) present in exhaust gas as a NOx reducing agent. have.

The problem to be solved by the present invention is not limited to the problem (s) mentioned above, and other object (s) not mentioned will be clearly understood by those skilled in the art from the following description.

In order to solve the above problems, a high performance nitrogen oxide reduction catalyst according to an embodiment of the present invention, a catalyst for reducing nitrogen oxides (NOx) in the exhaust gas, ruthenium and iridium is supported on the support, barium, potassium And one selected from the group consisting of cerium.

In one embodiment, it is preferable that one selected from the group consisting of barium, potassium and cerium is supported by 0.1 to 40 parts by weight based on 100 parts by weight of the support.

In one embodiment, it is preferable that the ruthenium (Ru) is supported at 0.1 to 10 parts by weight with respect to 100 parts by weight of the support.

In one embodiment, it is preferable that the iridium (Ir) is supported at 0.1 to 10 parts by weight with respect to 100 parts by weight of the support.

In one embodiment, it is preferable that ruthenium and iridium are first supported on the support, and then secondly, further, one selected from the group consisting of barium, potassium, and cerium is further supported.

In one embodiment, the support is preferably aluminum oxide.

In one embodiment, the catalyst is preferably calcined for 1 to 5 hours at a temperature of 300 ~ 900 ℃ under wet air.

Method for producing a high performance nitrogen oxide reduction catalyst according to another preferred embodiment of the present invention, (a) supporting ruthenium and iridium on a support; (b) supporting one selected from the group consisting of barium, potassium and cerium on the support of step (a); And (c) calcining the support of step (b).

In one embodiment, after the step (a), it is preferable to further include the step of calcining the support on which the ruthenium and iridium is carried out at a temperature of 300 ~ 900 ℃ for 1 to 5 hours under wet air.

In one embodiment, the step (c) is preferably performed for 1 to 5 hours at a temperature of 300 ~ 900 ℃ under wet air.

According to another embodiment of the present invention, the deNOx system is characterized by including the catalyst described above.

By using the high performance nitrogen oxide reduction catalyst and the production method thereof according to the present invention, there is an advantage that the removal efficiency of NOx present in the exhaust gas at any temperature can be improved.

In addition, there is an economic advantage because it does not need to introduce a separate reducing agent (urea) to remove the NOx present in the exhaust gas.

In addition, there is an economical advantage because the supply of urea (reducing agent) is not necessary.

1 is a flow chart showing a method for producing a high performance nitrogen oxide reduction catalyst according to an embodiment of the present invention.
Figure 2 compares the nitrogen oxide removal activity of the catalyst prepared according to Example 1 and Comparative Examples 1 to 4.
Figure 3 compares by measuring the nitrogen oxide removal performance prepared according to Example 1, Comparative Example 2 and Comparative Example 5.

Advantages and features of the present invention, and methods for achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention and to provide general knowledge in the technical field to which the present invention pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims.

Shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings for describing the embodiments of the present invention are exemplary, and the present invention is not limited thereto. Like reference numerals refer to like elements throughout.

In addition, in describing the present invention, if it is determined that the detailed description of the related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In the case where 'comprises', 'haves', 'consists of' and the like mentioned in the present specification are used, other parts may be added unless 'only' is used. In the case where the component is expressed in the singular, the plural includes the plural unless specifically stated otherwise.

In the case of the description of the positional relationship, for example, if the positional relationship of the two parts is described as 'on', 'upon', 'lower', 'next', etc. Alternatively, one or more other parts may be located between the two parts unless 'direct' is used.

In the case of a description of a temporal relationship, for example, if the temporal after-degree relationship is described as 'after', 'following', 'after', 'before', etc. This may include non-consecutive unless' is used.

Each of the features of the various embodiments of the present invention may be combined or combined with each other, partly or wholly, and various technically interlocking and driving are possible, and each of the embodiments may be implemented independently of each other or may be implemented together in an association. It may be.

Before describing the present invention, a brief description will be given of the SCR system in the deNOx technology.

The SCR system is used to reduce NOx in exhaust gases generated during the operation of land plants, ships, and automobiles. For example, an SCR system is required to reduce nitrogen oxides in exhaust gas generated from an engine or a boiler of a ship (especially an LNG carrier) or a boiler or an incinerator of a land plant. The SCR system is a NOx reduction system using a selective catalytic reduction method. The SCR system is configured to react NOx with a reducing agent and to reduce the nitrogen and water vapor while simultaneously passing the exhaust gas and the reducing agent in the catalyst. Recently, there have been many efforts to improve the SCR system. In spite of such efforts, the specificity of ships or some land plants does not produce definite results.

In general, SCR systems use NH ₃ and urea as reducing agents for NOx reduction. In addition, SCR systems utilize high temperature catalysts having an active temperature range of 0 ° C to 400 ° C. Therefore, in the conventional SCR system, a reheating system for heating the exhaust gas is installed in front of the casing of the SCR reactor in which the catalyst is installed in order to increase the reaction efficiency by matching the conditions of the active temperature range. In addition, the conventional SCR system is a dust collecting facility in the rear end of the SCR reactor casing to occupy a large space in order to reduce the particulate matter (PM), dust, and fine dust contained in the exhaust gas after the reaction in the SCR reactor. There is this.

An object of the present invention is to provide a deNOx catalyst capable of removing NOx at low and high temperatures without introducing a reducing agent by using carbon monoxide (CO) present in exhaust gas as a NOx reducing agent.

In addition, there is an economical advantage because the supply of urea (reducing agent) is not necessary.

Hereinafter, the high performance nitrogen oxide reduction catalyst which concerns on this invention is demonstrated.

By using the high performance nitrogen oxide reduction catalyst and the production method thereof according to the present invention, there is an advantage that the removal efficiency of NOx present in the exhaust gas at any temperature can be improved.

In addition, there is an economic advantage because it does not need to introduce a separate reducing agent to remove the NOx present in the exhaust gas.

In one embodiment of the present invention, the high performance nitrogen oxide reduction catalyst is a catalyst for reducing nitrogen oxides (NOx) in the exhaust gas, ruthenium and iridium is supported on the support, selected from the group consisting of barium, potassium and cerium One more species can be supported.

In one embodiment of the present invention, one selected from the group consisting of barium, potassium and cerium, may be supported by 0.1 to 40 parts by weight with respect to 100 parts by weight of the support, specifically 1 to 30% by weight Parts, more specifically 15 to 25 parts by weight.

In one embodiment of the present invention, the high performance nitrogen oxide reduction catalyst, the ruthenium (Ru) may be supported by 0.1 to 10 parts by weight with respect to 100 parts by weight of the support, specifically 0.1 to 5 parts by weight More specifically, it may be 1 to 2 parts by weight.

In addition, in one embodiment of the present invention, the high performance nitrogen oxide reduction catalyst, the iridium (Ir) may be supported by 0.1 to 10 parts by weight with respect to 100 parts by weight of the support, specifically 0.1 to 5 parts by weight Parts, more specifically, 1 to 2 parts by weight.

That is, the present invention is a high-performance nitrogen oxide reduction catalyst, wherein ruthenium and iridium are first supported on a support, and then NOx reduction catalyst formed by further supporting one selected from the group consisting of barium, potassium and cerium.

The loading amount of one kind selected from the group consisting of barium, potassium, and cerium is preferably in an appropriate range, but in order to sufficiently serve the purpose of increasing the removal efficiency of NOx at all temperatures, it is based on 100 parts by weight of the support. It may be 0.1 to 40 parts by weight, specifically 1 to 30 parts by weight, more specifically 15 to 25 parts by weight.

The barium is an element of atomic number 56, and the element symbol is Ba. It belongs to the alkaline earth metal group which is group 2 (group 2A) together with beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr) and radium (Ra). It is chemically similar to calcium or strontium, but with greater reactivity. It is a silvery white soft metal that, when exposed to air, readily reacts with oxygen and oxidizes, and also reacts with water and alcohol to generate hydrogen (H ₂ ) gas. Therefore, metal barium should be stored under inert gas or mineral oil such as petroleum with air blocking. When burned in air or oxygen, a light yellow-green flame is burned to form barium oxide (BaO) and barium peroxide (BaO ₂ ). Reacts with most nonmetallic elements and is soluble in most acids except sulfuric acid. The oxidation state in the compound is mainly +2.

The loading amount of the iridium is preferably in an appropriate range, but may be 0.1 to 10 parts by weight with respect to 100 parts by weight of the support, in order to fully achieve the purpose of increasing the NOx removal efficiency at all temperatures. 5 parts by weight, more specifically 1 to 2 parts by weight.

The iridium is an element of atomic number 77 and the element symbol is Ir. A transition metal belonging to group 9 (group 8B) in the periodic table together with cobalt (Co) and rhodium (Rh), one of the platinum group metals. Platinum group metals are elements of the 5th and 6th periods in groups 8, 9, and 10 of the periodic table: ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd), and platinum ( The six metal elements of Pt). Hard but less ductile and easily broken and difficult to machine. The mass is silver white, but the powder is black. The density is 22.56 g / cm at 20 ° C., next to osmium (density 22.59 g / cm) of all elements. Melting point is 2446 ℃, boiling point is 440 ℃.

The iridium is one of metals having the highest corrosion resistance, and does not react with air, water, acid, or alkali at room temperature, and does not dissolve in aqua regia. When heated to 800 ° C or above in the air or reacted with an oxidizing molten alkali, iridium dioxide (IrO ₂ ) is produced. IrO ₂ is dissolved in aqua regia and decomposes into elements at about 1,100 ° C or higher. It reacts with some molten salts and also with halogen elements at high temperatures. In compounds, oxidation states of -3 to +6 are present, but oxidation states of +3 and +4 exist in the most common state.

In addition, the iridium compounds may be used as a catalyst for various chemical reactions. For example, [IrI ₂ (CO) ₂ ]-can be used as a catalyst in the Cativa process that carbonylates methyl alcohol (CHOH) to produce acetic acid (CHCOOH).

The loading amount of ruthenium is preferably in an appropriate range, but 0.1 to 10 parts by weight, specifically 0.1 to 5 parts by weight, based on 100 parts by weight of the support so as to sufficiently serve the purpose of increasing the NOx removal efficiency at all temperatures. Parts, more specifically, 1 to 2 parts by weight.

Ruthenium, the element number 44, is a transition metal located at the center of the periodic table and is one of the platinum group metals. Transition metals are elements filled with electrons in the d-electron shell, which are generally hard, strong, colored complexes of various oxidation states, and have a common catalytic activity.

However, in detail, there is a significant difference between the early-transition metals in Group 7 and the late-transition metals in Groups 9-11. Ruthenium belonging to group 8 has a common property of both the front transition metal and the post transition metal, so it is a very useful transition metal. Ruthenium is a rare metal that is roughly the sixth in the smallest abundance of elements on Earth, with very low annual output. Thus, for most people, ruthenium will be considered a very new element. Ruthenium is mainly used as an alloy in the metal industry, as a catalyst in the chemical industry, and as an electrical contact and a resistive material in the electronic industry. It is also used for decorative and wear resistant plating of fine jewelry. Ruthenium complexes are also expected to be anticancer drugs and photocatalysts used to convert solar energy.

In the catalyst according to an embodiment of the present invention, ruthenium and iridium are supported on the support, and other precious metals may be additionally supported in addition to one selected from the group consisting of barium, potassium and cerium. If this is to increase the performance of the nitrogen compound reduction catalyst is not limited to this.

In one embodiment of the invention, the preferred additional catalyst component may be one or more selected from the group consisting of platinum, rhodium, palladium and silver. Particularly preferred among these additional precious metals are platinum and rhodium. In this case, it is preferable that platinum and rhodium contain 0.1-1 weight part of platinum with respect to 100 weight part of said support bodies. In addition, it is preferable that rhodium also contains 0.1-1 weight part with respect to 100 weight part of said supports. In order to exert the effect of supporting additional precious metals in the same manner as described above, the purpose is not to reduce the properties of ruthenium and iridium as main components. Furthermore, these additional metals may carry a plurality of them, and for example, may further carry two precious metals of platinum and rhodium with respect to iridium and ruthenium.

Platinum belongs to the rare element and ranks 74th in the Clark number, and is produced as an alloy with a free state or other cognate elements, and is mainly produced in Russia, Ural, South Africa, Colombia, Canada and the like. Purity is 75 to 85% and impurities are other platinum group elements.

It is a silver-white noble metal, harder than silver, and has malleability and ductility. Cold work can also be done, but usually it is processed by heating to 800 ~ 1,000 ℃. Adding a small amount of iridium can be a harder and stronger alloy while retaining the benefits of pure platinum. The expansion rate is almost the same as that of glass, which is convenient for joining glass appliances. Fine powdered platinum absorbs hydrogen at least 100 times its volume, and glowing platinum absorbs and permeates hydrogen. It is very stable to air, moisture, etc., and does not change even when heated to high temperature. It is resistant to acid and alkali and has high corrosion resistance. However, it slowly melts in aqua regia and erodes when heated to high temperature with caustic alkali. It reacts when heated with fluorine, chlorine, sulfur, selenium and the like.

Rhodium is an element of atomic number 45, and the element symbol is Rh. It is a silvery white shiny transition metal, one of the platinum group metals. Usually produced and sold forms are blackish brown in powder or sponge form. In the periodic table, together with cobalt (Co) and iridium (Ir), they belong to group 9, and the elements of groups 8 to 10 are also referred to as group 8B elements. Physical and chemical properties are closer to iridium or other platinum group metals than cobalt. It has a higher melting point and lower density than platinum. It is hard and does not wear well, the reflectance of light is large, does not oxidize at room temperature in air, and slowly oxidizes above 500 ° C to form rhodium oxide (Rh ₂ O ₃ ), but when heated further, it is decomposed into metal rhodium and oxygen again. . At high temperatures it reacts with sulfur and halogens. Insoluble in most acids, including nitric acid.

The palladium is a rare element of the 71st Clark number, but more than platinum or gold. It is contained as an alloy in platinum, gold and silver ores. It is a white metal, the lightest of the platinum group metals and the lowest melting point metal. It is malleable and ductile and alloys with almost all metals. Metals have the property of absorbing a large amount of gas, especially hydrogen, which absorbs about 850 times hydrogen at room temperature and atmospheric pressure, with a marked expansion. When the hydrogen is released in a vacuum, it is as active as generator hydrogen. It is relatively reactive among the platinum group elements, so it is easy to be eroded by acid and is well soluble in aqua regia. Mild heating in oxygen produces oxides, but does not change in humid air or ozone at room temperature. It reacts when heated with fluorine, chlorine, sulfur, selenium, phosphorus, arsenic, and silicon, and its main oxidation numbers are +2 and +4.

The silver is generally an off-white metal but also gray in powder. The second malleable and ductile property of metals, followed by gold, can produce very thin silver foils. In addition, it transfers heat and electricity best and has very good processability and mechanical properties. Metals such as silver, gold and platinum do not react easily with air or water. It reflects light well and is often used to make jewelry, and it is also called precious metal because the output is expensive due to its low output. The malleable and ductile metals are followed by gold, which, when melted, occludes large amounts of oxygen in the air and releases them violently when solidified. Thermal and electrical conductivity is the largest of the metals. It is stable in water and air, and does not rust very well, but turns to black silver peroxide in ozone and black silver sulfide in sulfur or hydrogen sulfide. It does not dissolve in normal acids or alkalis, but it dissolves in nitric acid and warm sulfuric acid, and nitric acid becomes silver sulfate, and the oxidation number of ordinary compounds is present in +1 and +2 valences.

In one embodiment of the present invention, the high-performance nitrogen oxide reduction catalyst, the ruthenium and iridium is first supported on the support, and secondly selected from the group consisting of barium, potassium and cerium further supported Can provide.

In one embodiment of the present invention, the high performance nitrogen oxide reduction catalyst may be supported on a mixture of ruthenium, iridium and barium on the support, but preferably, after ruthenium and iridium are first supported on the support, It is preferable that one selected from the group consisting of barium, potassium and cerium is supported thereon.

The support may be one selected from the group consisting of aluminum honeycomb, zirconia, titania, silica, zeolite and metal honeycomb such as ceramic or carbide, preferably aluminum oxide. In this case, the support may be supported on the iridium and ruthenium solutions to form a catalyst layer.

The specific surface area of the said aluminum oxide is 5 or more, specifically 50 or more, More preferably, 100 m <^2> / g or more is preferable.

When the specific surface area of the aluminum oxide is smaller than 5, there is a disadvantage in that the activity of the catalyst is inferior, the above range is preferable.

The aluminum oxide is generally called alumina and is colorless or white insoluble in water. α alumina is a product of the Bayer method. Melting Point 1999 ~ 2032 ℃. β-alumina is said to be a stable form at high temperature (1,500 ° C or more). (gamma) alumina is obtained by heating and dehydrating a hydrate or (alpha) hydrated alumina, and also maintaining it at 900 degreeC, and when it is 1000 degreeC or more, it has a characteristic of transition to alpha alumina.

The aluminum oxide exhibits a high specific surface area and good heat resistance to coarsening and sintering at elevated temperatures, making it preferred for use as a support for catalysts.

However, the aluminum oxide strongly interacts with the sulfur and sulfur compounds present in the fuel and then in the exhaust product, so that SO ₄ can be adsorbed on the surface of the aluminum oxide. When adsorbed in that way, sulfur compounds can shorten the life of common noble metal catalysts.

The zirconia is zirconium oxide (IV) ZrO ₂ , and is normally used as stabilized zirconia as an industrial material. It has a molecular weight of 123.22 and a melting point of about 2,700 ° C. The refractive index is large and the melting point is high, so the corrosion resistance is large. It does not dissolve in water, but dissolves in sulfuric acid and hydrofluoric acid. It can withstand rapid temperature change, so it can be used for equipment of rapid quenching and quenching.

The titania is an oxide of titanium, and absorbing the external rays can produce oxygen in the air or active oxygen having a strong oxidation power in water. Due to this, it is possible to act as an anti-pollution action, air purification action, antibacterial action, and environmentally friendly photocatalyst which is in the spotlight these days.

The silica is a chemical combination of silicon and oxygen (SiO ₂ ), and in nature, silica has five homogeneous crystals (quartz, tridymite, cristobalite, coesite, stishovite), silvery (chalcedony), amorphous, and hydrated (opal). It exists in various forms.

Zeolites, also called zeolites, have many types but commonalities in terms of high water content, crystal properties, and acid phase. Hardness does not exceed 6, specific gravity is about 2.2. Generally it is colorless transparent or white translucent. In addition, since the bond of each atom is loosely crystallized structurally, even if the moisture filling the space is released at high heat, the skeleton remains the same, so that other particulates can be adsorbed and used as a support for the catalyst.

In accordance with an embodiment of the present invention, the high performance nitrogen oxide reduction catalyst may provide a calcined for 1 to 5 hours at a temperature of 300 ~ 900 ℃ under wet air.

Only when the firing temperature is fired at more than 300 ℃ 900 ℃ can exhibit the effect of increasing the removal efficiency of the nitrogen oxide at all temperatures.

When the calcination comes over 900 ° C., there is a problem in that the activity of the catalyst is deteriorated due to catalyst volatilization and sintering.

Firing may be carried out under hydrogen, argon and air static pressure during firing, but it is preferable to carry out the firing under wet air.

The reason for the firing in the wet air is to remove the Cl component used as the precursor of the catalyst, because the catalyst performance is enhanced when the Cl component is removed during the preparation of the catalyst.

High-performance nitrogen oxide reduction catalyst according to an embodiment of the present invention is calcined for 1 to 5 hours at a temperature of 300 ~ 900 ℃ under wet air conditions, it is possible to provide a catalyst with improved nitrogen oxide removal efficiency at all temperatures.

Hereinafter, with reference to Figure 1 will be described in detail step by step a method for producing a high performance nitrogen oxide reduction catalyst according to an embodiment of the present invention.

Method for producing a high performance nitrogen oxide reduction catalyst according to an embodiment of the present invention, (a) supporting the ruthenium and iridium on the support (S100); (b) supporting at least one selected from the group consisting of barium, potassium and cerium on the support of step (a) (S200); And (c) firing the support of step (b) (S300).

In the method of manufacturing a high performance nitrogen oxide reduction catalyst according to an embodiment of the present invention, step (a) (S100) is a step (S100) of supporting ruthenium and iridium on a support.

The support may be one selected from the group consisting of aluminum honeycomb, zirconia, titania, silica, zeolite and metal honeycomb such as ceramic or carbide, preferably aluminum oxide. In this case, the support may be supported on the iridium and ruthenium solutions to form a catalyst layer.

The specific surface area of the aluminum oxide used as the support in step (a) (S100) is preferably 5 or more, specifically 50 or more, and more specifically 100 m ² / g or more.

When the specific surface area of the aluminum oxide that is the support is smaller than 5, there is a disadvantage that the activity of the catalyst is inferior, the above range is preferable.

The ruthenium (Ru) of the (a) step (S100), may be carried in 0.1 to 10 parts by weight with respect to 100 parts by weight of the support.

The amount of ruthenium supported is preferably in an appropriate range. Specifically, in order to fully achieve the purpose of increasing the NOx removal efficiency at all temperatures, specifically 0.1 to 10 parts by weight, specifically 0.1 to 100 parts by weight of the support. To 5 parts by weight, more specifically 1 to 2 parts by weight.

The iridium (Ir) of step (a) may be carried in 0.1 to 10 parts by weight in 100 parts by weight of the support.

Although the supporting amount of the iridium is preferably within an appropriate range, in order to sufficiently exhibit the purpose of increasing the NOx removal efficiency at all temperatures, the loading amount of iridium is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the support. It may be a portion, specifically 0.1 to 5 parts by weight, more specifically may be 1 to 2 parts by weight.

The step (a) (S100) may further include a catalyst component in addition to ruthenium and iridium, the preferred catalyst component may be one or more selected from the group consisting of platinum, rhodium, palladium and silver. Particularly preferred among these additional precious metals are platinum and rhodium. In this case, it is preferable that platinum and rhodium contain 0.1-1 weight part of platinum with respect to 100 weight part of said support bodies. In addition, it is preferable that rhodium also contains 0.1-1 weight part with respect to 100 weight part of said support bodies. In order to exert the effect of supporting an additional precious metal similarly to the above, in order not to reduce the characteristic of the iridium which becomes a main component. Moreover, these additional metals may be supported on a plurality.

After the step (a) (S100), the step of calcining the support on which the ruthenium and iridium of the step (a) is carried out at a temperature of 300 ~ 900 ℃ 1 to 5 hours may be further included.

After the step (a) (S100), the step of firing is performed so that ruthenium and iridium do not leave the support.

The step (a) (S100) may be carried out by adding the support to the ruthenium and iridium mixture and put out and calcined at 300 ~ 900 ℃ for 1 to 5 hours, the step of sequentially adding and calcining the ruthenium and iridium Can be

In the method for producing a high performance nitrogen oxide reduction catalyst according to an embodiment of the present invention, the step (b) (S200), (b) is selected from the group consisting of barium, potassium and cerium (a) It is a step (S200) supported on the support of the step.

Wherein (b) step (S200) is a step (S200) of supporting one selected from the group consisting of barium, potassium and cerium on the support of the step (a), preferably in 100 parts by weight of the support The one selected from the group consisting of barium, potassium and cerium may include 0.1 to 40 parts by weight. That is, the amount of one supported material selected from the group consisting of barium, potassium and cerium is preferably in an appropriate range, but 100 parts by weight of the support to sufficiently exhibit the purpose of increasing the removal efficiency of nitrogen oxide at all temperatures It may be 0.1 to 40 parts by weight, specifically 1 to 30 parts by weight, more specifically 15 to 25 parts by weight.

In the method for producing a high performance nitrogen oxide reduction catalyst according to an embodiment of the present invention, the step (c) (S300) is a step (S300) of firing the support of the step (b) (S200).

Step (c) (S300) may be performed for 1 to 5 hours at a temperature of 300 ~ 900 ℃ under wet air.

When the firing temperature of step (c) is performed at 300 ° C. or lower, the activity of the resulting catalyst is lowered. When the firing temperature is performed at 900 ° C. or higher, Cl molecules are adsorbed to decrease the activity of the catalyst. The above range is preferable because there is a problem.

According to one embodiment of the present invention can provide a deNOx SCR system comprising the catalyst described above.

DeNOx SCR system according to an embodiment of the present invention, the diesel particulate filter for removing particulate matter in the exhaust gas flowing from the diesel engine; A diesel oxidation catalyst disposed between the diesel engine and the diesel particulate filter; And a NOx abatement device disposed behind the diesel particulate filter to decompose nitrogen oxides contained in the exhaust gas, wherein the NOx abatement device is disposed therein to remove nitrogen oxides in the exhaust gas that has passed through the diesel particulate filter. At least one catalyst prepared according to the invention may be arranged.

By using the high performance nitrogen oxide reduction catalyst and the production method thereof according to the present invention, there is an advantage that the removal efficiency of NOx present in the exhaust gas at any temperature can be improved.

In addition, there is an economic advantage because it does not need to introduce a separate reducing agent to remove the NOx present in the exhaust gas.

In addition, there is an economical advantage because the supply of urea (reducing agent) is not necessary.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples. However, the following Examples and Experimental Examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example 1 Ba-IrRu / Al ₂ O ₃  Preparation of catalysts 1

First, 0.190 g of IrCl ₃ sample and 0.193 g of RuCl ₃ sample were dissolved in water, and then dipped in 5 g of γ-aluminum oxide and dried at 100 ° C. for 12 hours. After drying, the sample was calcined under humid air at a temperature of 500 ° C. for 4 hours to complete the preparation of the (IrRu / Al ₂ O ₃ ) catalyst on which iridium-ruthenium was supported on aluminum oxide. 1.86 g of barium acetate (Ba (CH ₃ CO ₂ ) ₂ ) was dissolved in water, and then IrRu / Al ₂ O _{3 prepared} Supported by catalyst. It was dried at 100 ° C. for 12 hours and then calcined at 500 ° C. under stagnant air for 4 hours to complete the preparation of the (Ba-IrRu / Al ₂ O ₃ ) catalyst on which barium-iridium-ruthenium was supported on aluminum oxide. It was.

At this time, the amount of ruthenium supported by this catalyst was 1.52 parts by weight based on 100 parts by weight of the total catalyst, 2.11 parts by weight of iridium, and 20 parts by weight of barium.

Example  2 : Ba - IrRu Of Al ₂ O ₃  Preparation of catalysts 2

First, 0.190 g of IrCl ₃ sample and 0.193 g of RuCl ₃ sample were dissolved in water, and then dipped in 5 g of γ-aluminum oxide and dried at 100 ° C. for 12 hours. After drying, the sample was calcined under wet air at a temperature of 700 ° C. for 4 hours to complete the preparation of the (IrRu / Al ₂ O ₃ ) catalyst on which aluminum oxide was loaded with iridium-ruthenium. 1.86 g of barium acetate (Ba (CH ₃ CO ₂ ) ₂ ) was dissolved in water, and then IrRu / Al ₂ O _{3 prepared} Supported by catalyst. It was dried at 100 ° C. for 12 hours and then calcined at 700 ° C. under stagnant air for 4 hours to complete the preparation of the (Ba-IrRu / Al ₂ O ₃ ) catalyst on which barium-iridium-ruthenium was supported on aluminum oxide. It was.

At this time, the amount of ruthenium supported by this catalyst was 1.52 parts by weight based on 100 parts by weight of the total catalyst, 2.11 parts by weight of iridium, and 20 parts by weight of barium.

Example  3: K- IrRu Of Al ₂ O ₃  Preparation of the catalyst

The same procedure as in Example 1 was carried out using potassium instead of barium.

Example  4 : Ce - IrRu Of Al ₂ O ₃  Preparation of the catalyst

The same procedure as in Example 1 was carried out using cerium instead of barium.

Comparative example  One : IrRu Of Al ₂ O ₃  Preparation of the catalyst

First, 0.190 g of IrCl ₃ sample and 0.193 g of RuCl ₃ sample were dissolved in water, and then dipped in 5 g of γ-aluminum oxide and dried at 100 ° C. for 12 hours. After drying, the sample was calcined under humid air at a temperature of 500 ° C. for 4 hours to complete the preparation of the (IrRu / Al ₂ O ₃ ) catalyst on which iridium-ruthenium was supported on aluminum oxide.

At this time, the supported amount of Ru and Ir was 1.52 parts by weight based on 100 parts by weight of the total catalyst, and the supported amount of Ir was 2.11 parts by weight.

Comparative Example 2: IrPd / Al ₂ O ₃  Preparation of the catalyst

In the same manner as in Comparative Example 1, a catalyst was prepared using Pd instead of Ru.

At this time, the amount of Pd and Ir supported was 1.52 parts by weight based on 100 parts by weight of the total catalyst, and the amount of Ir was 2.11 parts by weight.

Comparative Example 3: IrMo / Al ₂ O ₃  Preparation of the catalyst

A catalyst was prepared in the same manner as in Comparative Example 1, but using Mo instead of Ru.

At this time, the amount of Mo and Ir supported on the basis of 100 parts by weight of the total catalyst was 1.52 parts by weight of Mo, and the amount of Ir was 2.11 parts by weight.

Comparative Example 4: IrAg / Al ₂ O ₃  Preparation of the catalyst

A catalyst was prepared in the same manner as in Comparative Example 1, using Ag instead of Ru.

At this time, the loading amount of Ag and Ir was 1.52 parts by weight based on 100 parts by weight of the total catalyst, and the loading amount of Ir was 2.11 parts by weight.

Comparative Example 5: Pt-Ba / Al ₂ O ₃  Preparation of the catalyst

The catalyst was prepared in the same manner as in Comparative Example 1, using Pt and Ba instead of Ru and Ir.

Experimental Example 1 Check the NOx Removal Performance

For the catalysts prepared according to Example 1 and Comparative Examples 1 to 4, nitrogen oxide removal activity was measured under the following measurement conditions.

Nitrogen oxides (NO): 50 ppm

CO: 0.7%

O ₂ : 5%

H ₂ O: measured at 5% and N ₂ balance and GHSV 200,000 h ^-1 and the results are shown in FIG.

<Evaluation>

Figure 2 compares the nitrogen oxide removal activity of the catalyst prepared according to Example 1 and Comparative Examples 1 to 4.

Referring to FIG. 2, the catalysts prepared according to Comparative Examples 1 to 4 exhibited activity at specific temperatures, while Ba-IrRu / Al ₂ O ₃ catalysts prepared in Example 1 ranged from 170 to 350 ° C. in all temperatures. It can be confirmed that the high removal rate of NOx is shown in the activity.

This broadens the active temperature range of the catalyst, which is a problem of the conventional urea SCR catalyst, and shows that it is effective in increasing the NOx removal rate even at low and high temperatures.

Experimental Example 2 Long-run test

Nitrogen oxide removal performance prepared according to Example 1, Comparative Example 2 and Comparative Example 5 was measured.

The nitrogen oxide removal activity of the catalysts prepared according to Example 1, Comparative Example 2 and Comparative Example 5 was measured under the following measurement conditions.

Nitrogen oxides (NO): 50 ppm

CO: 0.7%

O ₂ : 5%

H ₂ O: 5% and N ₂ balance and T = 300 ℃, GHSV 200,000 h ^-1 measured under the conditions shown in Figure 3 the results.

<Evaluation>

Referring to FIG. 3, it can be seen that the catalysts prepared according to Comparative Examples 2 and 5 decrease the NOx removal efficiency with time, whereas the Ba-IrRu / Al ₂ O ₃ catalyst prepared according to Example 1 was slightly Decreased intervals of, but high nitrogen oxide removal performance can be confirmed.

This means that the Ba-IrRu / Al ₂ O ₃ catalyst prepared according to the present invention not only shows an initial high performance but also can be used while maintaining a long life.

So far, specific embodiments of a high performance nitrogen oxide reduction catalyst and a method for preparing the same according to an embodiment of the present invention have been described, but various embodiments can be modified without departing from the scope of the present invention.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

In other words, the foregoing embodiments are to be understood in all respects as illustrative and not restrictive, the scope of the invention being indicated by the following claims rather than the detailed description, and the meaning and scope of the claims and All changes or modifications derived from the equivalent concept should be interpreted as being included in the scope of the present invention.

S100: supporting ruthenium and iridium on the support
S200: supporting one selected from the group consisting of barium, potassium and cerium on the support of step (a)
S300: calcining the support of the step (b)

Claims (11)

A catalyst for reducing nitrogen oxides (NOx) by using carbon monoxide (CO) in exhaust gas as a reducing agent,
Ruthenium and iridium are supported on the support and calcined under wet air,
High performance nitrogen oxide reduction catalyst characterized in that one selected from the group consisting of barium, potassium and cerium is further supported.
The method of claim 1,
The high-performance nitrogen oxide reduction catalyst, characterized in that one selected from the group consisting of barium, potassium and cerium is supported by 0.1 to 40 parts by weight based on 100 parts by weight of the support.
The method of claim 1,
The ruthenium (Ru) is,
High performance nitrogen oxide reduction catalyst, characterized in that supported by 0.1 to 10 parts by weight based on 100 parts by weight of the support.
The method of claim 1,
The iridium (Ir) is,
High performance nitrogen oxide reduction catalyst, characterized in that supported by 0.1 to 10 parts by weight based on 100 parts by weight of the support.
The method of claim 4, wherein
High performance nitrogen oxide reduction catalyst, characterized in that the support is primarily supported on the support ruthenium and iridium and then secondarily selected from the group consisting of barium, potassium and cerium.
The method of claim 5,
The support is a high performance nitrogen oxide reduction catalyst, characterized in that the aluminum oxide.
The method of claim 6,
The catalyst is,
A high performance nitrogen oxide reduction catalyst, which is calcined for 1 to 5 hours at a temperature of 300 to 900 ° C. under wet air.
A catalyst for reducing nitrogen oxides (NOx) by using carbon monoxide (CO) in exhaust gas as a reducing agent,
(a) supporting ruthenium and iridium on a support;
(b) supporting one selected from the group consisting of barium, potassium and cerium on the support of step (a); And
(c) calcining the support of step (b);
To include, after the step (a),
The ruthenium and the iridium-supported support method further comprises the step of firing for 1 to 5 hours at a temperature of 300 ~ 900 ℃ under wet air.
delete The method of claim 8,
In step (c),
Method for producing a high performance nitrogen oxide reduction catalyst, characterized in that carried out for 1 to 5 hours at a temperature of 300 ~ 900 ℃ under wet air.
A deNOx system comprising the step of removing nitrogen oxides by the catalyst according to any one of claims 1 to 7.

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