KR102127133B1 - Ir-based deNOx catalyst and its preparation method - Google Patents

Abstract

Ir-based deNOx catalyst according to the present invention is a catalyst for reducing nitrogen oxides (NOx) by utilizing CO in the exhaust gas as a reducing agent, where ruthenium and iridium are supported on a support and calcined under wet air, and the iridium is 100 wt. With respect to the part, it is characterized in that supported on 0.1 to 10 parts by weight. The use of the Ir-based deNOx catalyst and its manufacturing method according to the present invention has an advantage of increasing the removal efficiency of NOx present in the exhaust gas even at a low temperature of 180°C. In particular, after the actual aging of the catalyst, it has the effect of showing superior performance over the existing deNOx system. In addition, unlike urea water SCR, there is no need to introduce a separate external reducing agent to remove NOx present in the exhaust gas, so the device becomes simple and has economical advantages in installation cost, maintenance cost, and raw material cost. In particular, it is possible to impart additional deNOx performance to LNT and DOC, or TWC outside the scope of the conventional urea SCR, and also to reduce CO and hydrocarbons.

Description

Ir-based deNOx catalyst and its preparation method

The present invention relates to an Ir-based deNOx catalyst and a method of manufacturing the same, and more particularly, to a method of manufacturing an Ir-based deNOx catalyst having improved NOx reduction rate 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 plants and animals. Nitrogen oxides exist in the form of NO, NO ₂ , N ₂ O, N ₂ O ₄ , and 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, as it is converted to nitric acid and nitrate, which causes acid rain, as well as visibility disorders and greenhouse effects. In addition, hemoglobin has a strong adsorption performance of 20,000 times that of O ₂ and is known as a substance that can cause great harm when the concentration is high, and efforts to reduce it are urgently requested.

Nitrogen oxides are on the rise, and when looking at the NOx emission ratio by fuel, gas 7%, Oil 64%, and Coal 29%, and by NOx emission ratio by source, automobile 49%, industrial plant 30%, power plant It is generated by 15% and 6% of heating.

The path of nitrogen oxide emission is largely about 5% of fuel NOx by combustion of nitrogen components present in fuel oil, and prompt NOx generated near the flame surface in the presence of hydrocarbon occupies a small level. Thermal NOx generated during combustion of fuel oil is occupied.

As such, in order to reduce the emission of nitrogen oxide, the main cause of air pollution in cities, it is legally regulated in many countries. In Japan, the new gas, oil, and coal-fired power plants are 60, 130, and 200 ppm, respectively. However, in order to achieve atmospheric nitrogen oxide concentrations regulated by local governments, power plants are operating below 15, 30, and 60 ppm, far below the norm, and gas turbines are operating at below 5 ppm. European limits are 30-50, 55-75, 50-100 ppm for power plants and 25 ppm for gas turbines. Methods to reduce nitrogen oxides are needed to satisfy these regulatory values. Among them, the pre-treatment technology through the combustion method includes reducing the amount of excess air, cooling the combustion portion, reducing the air preheating temperature, recirculating 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, the introduction of a post-treatment device is essential to effectively control them. In addition, in the case of a wet method such as a method of absorbing water, hydroxide or carbonate solution, sulfuric acid, etc., the efficiency is good, but a large amount of absorbent is required when treating a large-capacity gas, and the solution in which nitrogen oxide is absorbed is treated as secondary wastewater You have a problem to do. Even in the case of the dry method, the method using an adsorbent such as molecular sieve or activated carbon is a method that is used when a small amount of nitrogen oxide is contained in the flue gas, and is difficult to apply when the amount of nitrogen oxide to be adsorbed increases. have.

For this reason, current technologies for NOx removal from most combustion gases currently use selective catalytic reduction (SCR) technology. The selective catalytic reduction process utilizes a catalyst bed or system to treat the flue gas stream through selective conversion of NOx to N ₂ (reduction). The SCR process usually uses ammonia or an element decomposing to ammonia as a reducing reactant injected into the upstream flue gas stream prior to contact with the catalyst. In commercial applications, SCR systems can achieve NOx removal rates of typically over 60%.

In the case of an SCR catalyst that is generally used, when a urea solution is injected with a dosing module disposed at the front end in order to maintain NOx purification performance above a certain level, it is thermally decomposed by the heat of the exhaust gas, and the SCR catalyst The ammonia (NH) produced by the hydrolysis of the material is stored, and can be purified by reacting the ammonia with NOx.

On the other hand, as a disadvantage, it is necessary to have a system in order to supply the liquid urea to the catalyst, and there is an additional system such as a container and an injection device for storing the liquid urea. There are disadvantages. In addition, the conventional liquid urea system has a problem in that urea is not vaporized and solid ammonium is generated when the exhaust gas temperature is injected at a temperature of 200° C. or less because the urea must be vaporized by the heat from the exhaust gas. come. In addition, since urea needs to be supplied periodically from the outside, there is inconvenience and additional management cost.

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

The present invention is proposed to solve the above problems, by using carbon monoxide (CO) present in the exhaust gas as a NOx reducing agent, a high-performance Ir-based deNOx catalyst capable of removing NOx without introducing a separate reducing agent such as urea and its preparation The purpose is to provide a method.

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

In order to solve the above problems, according to a preferred embodiment of the present invention, the Ir-based deNOx catalyst is a catalyst for reducing nitrogen oxides (NOx) by using CO in the exhaust gas as a reducing agent, where ruthenium and iridium are supported on the support. It is characterized in that it is calcined under wet air, and the iridium is supported in an amount of 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 ruthenium (Ru) is supported in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the support.

In one embodiment, the firing is preferably calcined for 1 to 10 hours at a temperature of 300 to 800°C under wet air.

In one embodiment, it is preferable that ruthenium is firstly supported on the support and then iridium is secondarily supported.

In one embodiment, the support is preferably aluminum oxide.

In one embodiment, the Ir-based deNOx catalyst is preferably any one selected from the group consisting of a group of TWC, LNT or SCR catalysts.

According to a preferred embodiment of the present invention, a method for preparing an Ir-based deNOx catalyst includes: (a) preparing a mixture of ruthenium and iridium; (b) supporting a ruthenium and iridium mixture on a support; And (c) calcining the support on which ruthenium and iridium of step (b) are supported.

In one embodiment, the step (c), it is preferably performed for 1 to 10 hours at a temperature of 300 ~ 800 ℃ under wet air.

In one embodiment, the deNOx catalyst is preferably any one selected from the group consisting of TWC, LNT or SCR catalysts.

According to another preferred embodiment of the present invention, a method for preparing an Ir-based deNOx catalyst includes: (a) supporting ruthenium on a support; (b) supporting iridium on the support of step (a); And (c) calcining the iridium-supported support of step (b) under moist air.

In one embodiment, after the step (a), it is preferable to further include the step of firing the support for supporting the ruthenium for 1 to 10 hours at a temperature of 300 ~ 800 ℃.

* In one embodiment, the step (c), it is preferably performed for 1 to 10 hours at a temperature of 300 ~ 800 ℃.

In one embodiment, the deNOx catalyst is preferably any one selected from the group consisting of TWC, LNT or SCR catalysts.

According to another preferred embodiment of the invention, the deNOx system is characterized in that it comprises a NOx removal process by means of a catalyst prepared according to the invention.

The use of the Ir-based deNOx catalyst and its manufacturing method according to the present invention has an advantage of increasing the removal efficiency of NOx present in the exhaust gas even at a low temperature of 180°C. In particular, after the actual aging of the catalyst, it has the effect of showing superior performance over the existing deNOx system.

In addition, unlike urea water SCR, there is no need to introduce a separate external reducing agent to remove NOx present in the exhaust gas, so the device becomes simple and has economical advantages in installation cost, maintenance cost, and raw material cost. In particular, it is possible to impart additional deNOx performance to LNT and DOC, or TWC outside the scope of the conventional urea SCR, and also to reduce CO and hydrocarbons.

1 is a flow chart showing a method of manufacturing an Ir-based deNOx catalyst according to an embodiment of the present invention.
2 is a flow chart showing a method of manufacturing an Ir-based deNOx catalyst according to another embodiment of the present invention.
3 is a comparison of nitrogen oxide removal activity of the catalysts prepared according to Examples 1 to 5 and Comparative Examples 1 to 4.
4 is a comparison of nitrogen oxide removal activity according to the loading order of iridium and ruthenium of Example 1, Example 5 and Comparative Example 5.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete, and have ordinary knowledge in the technical field to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining embodiments of the invention are exemplary and the present invention is not limited to the illustrated matters. The same reference numerals refer to the same components throughout the specification.

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

When'include','have','consist of', etc. mentioned in this specification are used, other parts may be added unless'~man' is used. When a component is expressed as a singular number, the plural number is included unless otherwise specified.

In the case of the description of the positional relationship, for example, when the positional relationship of two parts is described as'~top','~upper','~bottom','~side', etc.,'right' Alternatively, one or more other parts may be located between the two parts unless'direct' is used.

In the case of the description of the time relationship, for example,'after','following','~after','~before', etc. When the temporal sequential relationship is explained,'right' or'directly' It may also include cases that are not continuous unless' is used.

Each of the features of the various embodiments of the present invention may be partially or totally combined or combined with each other, technically various interlocking and driving may be possible, and each of the embodiments may be independently performed with respect to each other or may be implemented together in an association relationship. It might be.

Before explaining the present invention, an SCR system using ammonia (NH ₃ ) or ammonia precursor urea will be briefly described.

The SCR system is used to reduce NOx in exhaust gas generated during operation of onshore plants, ships, and automobiles. For example, an SCR system is required to reduce nitrogen oxides in exhaust gas generated from an engine or boiler of a vessel subject to vessel IMO regulation) or a boiler or incinerator of an onshore plant. The SCR system is a NOx reduction system using a selective catalytic reduction method, and is configured to react NOx with a reducing agent while simultaneously passing exhaust gas and a reducing agent in the catalyst to reduce the nitrogen and water vapor. In recent years, a lot of efforts have been made to improve the SCR system. Despite such efforts, certain results have not been achieved due to the specificity of ships or some onshore plants.

In general, the SCR system uses urea to provide NH ₃ or NH ₃ as a reducing agent for NOx reduction. In addition, the SCR system uses a catalyst having an active temperature range of 200°C to 400°C. Therefore, in the conventional SCR system, in order to increase the reaction efficiency by meeting the conditions of the active temperature range, a reheating system for heating exhaust gas is installed at the front end of the casing of the SCR reactor in which the catalyst is installed. In addition, the conventional SCR system, in order to reduce PM (Particle Material), dust, and fine dust contained in the exhaust gas that has been reacted in the SCR reactor, becomes a dust collection facility at the rear end of the SCR reactor casing and takes up a large space. There is this. Moreover, since the conventional SCR system has a weak function of removing harmful components such as hydrocarbon and carbon monoxide, there is a problem in that an oxidation catalyst system and the like must be additionally installed for a comprehensive reduction of harmful gases.

The present invention is proposed to solve the above problems, by using carbon monoxide (CO), which is originally present in the exhaust gas or can be supplied from the emission source as a NOx reducing agent, it is possible to remove NOx without introducing a separate reducing agent. The purpose is to provide a manufacturing method.

When the method of manufacturing an Ir-based deNOx catalyst according to the present invention is used, not only can NOx present in the exhaust gas be effectively reduced even at a low temperature of 180°C, carbon monoxide and hydrocarbons can also be simultaneously reduced.

In addition, unlike urea SCR, there is an economical advantage because a separate reducing agent is not required to remove NOx present in the exhaust gas.

In particular, it is possible to impart additional deNOx performance to LNT, DOC, or TWC outside the scope of the conventional urea SCR, and also to reduce CO and hydrocarbon.

The lean NOx trap (LNT) is a catalyst for reducing NOx by activating the reaction by providing H ₂ as a reducing agent by promoting the steam reforming reaction of hydrocarbons and water gas conversion, and the three-way conversion (TWC) catalyst is stoichiometric air, It is a catalyst that reduces NOx, CO and HC in engines operating at or near fuel conditions.

According to an embodiment of the present invention, the Ir-based deNOx catalyst is a catalyst for reducing nitrogen oxides (NOx) by utilizing CO in the exhaust gas as a reducing agent, where ruthenium and iridium are supported on a support and calcined under wet air. Iridium may provide one supported by 0.1 to 10 parts by weight based on 100 parts by weight of the support.

In addition, according to an embodiment of the present invention, the Ir-based deNOx catalyst may provide that the ruthenium (Ru) is supported in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the support.

The calcination may be calcined for 1 to 10 hours at a temperature of 300 to 800°C under moist air, and specifically, may be 400 to 750°C.

The loading amount of the iridium is preferably in an appropriate range, but in order to sufficiently exhibit the purpose of increasing NOx removal efficiency at low temperature, specifically, with respect to 100 parts by weight of the support, iridium is wetted at 0.1 to 10 parts by weight It is preferable to be supported under conditions. 0.1% by weight of the iridium loading amount is a minimum loading amount to secure the activity of the catalyst. On the other hand, with respect to 10 parts by weight, the above-mentioned range is preferable because the improvement of activity is insignificant and economically unfavorable even if it is loaded more than this.

* The iridium is an element of atomic number 77, and the element symbol is Ir. It is a transition metal belonging to group 9 (group 8B) in the periodic table together with cobalt (Co) and rhodium (Rh), and is one of the platinum group metals. Platinum group metals are elements of periods 5 and 6 in groups 8, 9, and 10 of the periodic table, namely ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd), platinum ( Refers to the six metal elements of Pt). Hard but ductile and easy to break and difficult to process. The mass is silvery white, but the powder is black. The density is 22.56 g/cm at 20° C., which is the second highest after osmium (density 22.59 g/cm) among all elements. The melting point is 2446℃, and the boiling point is 4,430℃.

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

In addition, the iridium compounds can be used as catalysts for various chemical reactions. For example, [IrI ₂ (CO) ₂ ]- can be used as a catalyst in the Cativa Process to make acetic acid (CHCOOH) by carbonylation of methyl alcohol (CHOH).

The carrying amount of the ruthenium is preferably in an appropriate range, but in order to sufficiently exhibit the purpose of increasing NOx removal efficiency at low temperature, specifically, with respect to 100 parts by weight of the support, ruthenium is 0.1 to 10 parts by weight under wet conditions It is desirable to be supported.

The ruthenium loading amount of 0.1% by weight is the minimum loading amount for securing the activity of the catalyst. On the other hand, with respect to 10 parts by weight, the above-mentioned range is preferable because the improvement of activity is insignificant and economically unfavorable even if it is loaded more than this.

The atomic number 44, ruthenium, is a transition metal located in the center of the periodic table and is one of the platinum group metals. Transition metal is an element that is filled with electrons in the d-electron shell, and has a common property of forming a complex compound having various oxidation states, which are generally hard and strong, and exhibit catalytic activity.

However, in detail, the periodic table shows significantly different characteristics between an early-transition metal belonging to group 7 and a late-transition metal belonging to group 9-11. Ruthenium, which belongs to Group 8, is a transition metal with great applicability because it has both common characteristics of the front transition metal and the post transition metal. Ruthenium is a very rare metal that ranks roughly sixth among the elements on Earth and has a low abundance, and its annual production is very low. Therefore, for most people, ruthenium will be considered a very new element. Ruthenium is mainly used as an alloying agent in the metal industry, as a catalyst in the chemical industry, and as an electrical contact and resistance material in the electronics industry. It is also used for decorative and abrasion resistant plating of high-grade ornaments. In addition, ruthenium complex compounds are also anticipating elements such as anticancer drugs and photocatalysts used in solar energy conversion.

And, in the IR-based deNOx catalyst according to an embodiment of the present invention, other precious metals other than ruthenium and iridium may be additionally supported, thereby not limiting it in the range of increasing the removal rate of NOx.

In one embodiment of the present invention, the preferred additional catalyst component for the ruthenium and iridium may be one or more selected from the group consisting of platinum, rhodium, palladium and silver. Among these additional noble metals, platinum, rhodium and silver are particularly preferred. In this case, it is preferable that platinum, rhodium and silver contain 0.1 to 10 parts by weight of platinum with respect to 100 parts by weight of the support. In addition, rhodium and silver also preferably contain 0.1 to 10 parts by weight of rhodium relative to 100 parts by weight of the support. In the same way as above, it is to prevent the deterioration of the properties of ruthenium and iridium as the main components, while exerting the effect of supporting additional precious metals. Moreover, a plurality of these additional metals may be supported, and for example, two precious metals of platinum and rhodium may be additionally supported on iridium and ruthenium.

The platinum belongs to a rare element and has the 74th number of Clarks. It is calculated as a free state or as an alloy with other cognate elements, and is mainly produced by Russia's Ural region, South Africa, Colombia, Canada, and the like. Purity is 75 to 85% and impurities are other platinum group elements.

In addition, it is a silver-white precious metal that is harder than silver and has malleability and ductility. Cold working may also be performed, but is usually performed by heating to 800 to 1,000°C. Adding a small amount of iridium can be a harder, stronger alloy while retaining the benefits of pure platinum. The expansion rate is almost the same as that of glass, which is convenient for bonding glass devices. Platinum made of fine powder absorbs hydrogen more than 100 times its volume, and glowing platinum absorbs hydrogen and permeates it. It is very stable in air and moisture, and does not change even when heated at a high temperature. It is resistant to acids and alkalis and has high corrosion resistance. However, it slowly melts in royal water and erodes when heated to high temperatures with caustic alkali. It reacts when heated with fluorine, chlorine, sulfur and selenium.

The rhodium (Rhodium) is an element of atomic number 45, the element symbol is Rh. It is a transition metal with a silver-white luster and is one of the platinum group metals. Usually produced and sold in the form of powder or sponge, it has a dark brown color. In the periodic table, cobalt (Co) and iridium (Ir) belong to group 9, and groups 8 to 10 elements are also called group 8B elements. Physical and chemical properties are closer to iridium or other platinum group metals than to cobalt. It has a higher melting point and lower density than platinum. It is hard and does not wear well, the light reflectance is large, it is not oxidized at room temperature in air, and is slowly oxidized above 500℃ to produce rhodium oxide (Rh ₂ O ₃ ), but upon further heating, it is decomposed into metal rhodium and oxygen again. . At high temperatures, it reacts with sulfur and halogen elements. Insoluble in most acids, including nitric acid.

The palladium is the rarest element of the 71st number of Clarks, but more than platinum or gold. It is contained in platinum, gold, and silver ores as alloys. It is a white metal and is the lightest and lowest melting point among platinum group metals. It has good malleability, ductility, and alloys with almost all metals. The metal has a property of absorbing a large amount of gas, especially hydrogen, and absorbs about 850 times hydrogen at normal temperature and pressure, and expands clearly at this time. When this hydrogen is released in a vacuum, it has a strong activity like generator hydrogen. It is relatively reactive among platinum group elements, so it is easily eroded by acids and soluble in aqua regia. Mild heating in oxygen produces oxide, but does not change in humid air or ozone at room temperature.

The silver is generally an off-white metal, but may be gray in the case of powder. After metal, it has the best malleability and ductility properties after gold, making it very thin silver foil. 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 is often referred to as a precious metal because it reflects light well and is used to make ornaments. The malleability and ductility are large following gold, and when melted, they absorb a large amount of oxygen in the air and release them violently when solidified. The conductivity of heat and electricity is the greatest among metals. It is stable in water and air, and does not rust well, but turns into black silver peroxide in ozone and black silver sulfide in sulfur or hydrogen sulfide. Insoluble in normal acid or alkali, but dissolved in nitric acid and warm sulfuric acid, it becomes silver nitrate and silver sulfate, and the oxidation number of compounds is usually +1 and +2.

According to an embodiment of the present invention, the Ir-based deNOx catalyst may provide that ruthenium is firstly supported on the support and then iridium is secondarily supported.

According to an embodiment of the present invention, the Ir-based deNOx catalyst may include a mixture of ruthenium and iridium on the support, but preferably, the support is primarily supported on ruthenium and then secondary to iridium. It is desirable to be supported.

According to an embodiment of the present invention, the Ir-based deNOx catalyst may firstly be supported with ruthenium on the support, and then secondary with iridium, and iridium and ruthenium to prevent iridium from being firstly supported. It can be supported at the same time.

According to an embodiment of the present invention, the Ir-based deNOx catalyst, a mixture of ruthenium and iridium on the support may be supported under dry conditions, but preferably supported under wet conditions.

When the support is first supported on iridium and then supported on ruthenium, the synergistic effect of iridium and ruthenium cannot be expected because iridium and ruthenium exist individually due to strong interaction between iridium and the support. When the support is first supported on ruthenium and then supported on iridium, strong interaction between the support and iridium can be prevented, and the iridium and ruthenium may be present nearby, thereby improving low-temperature performance.

In addition, even when the support is supported on a mixture of iridium and ruthenium, the mixture of iridium and ruthenium may be present close to exhibit a low-temperature performance enhancing effect.

That is, the present invention, as a catalyst for removing NOx in the exhaust gas, a diesel exhaust gas formed by simultaneously supporting iridium and ruthenium and firing under wet conditions to prevent the support, ruthenium and iridium from being firstly supported It is a NOx reduction catalyst.

According to an embodiment of the present invention, the support may be one selected from the group consisting of aluminum oxide, zirconia, titania, silica, zeolite, ceria, and ceria-based multi-component compounds, specifically aluminum oxide. . At this time, the support may be monolithized to be supported on the iridium and ruthenium precursor solution to form a catalyst layer.

In addition, the support may include a ruthenium layer and an iridium layer sequentially on a monolith, the ruthenium layer may be supported on the outer surface and inner pores of the support, and an iridium layer is formed on the ruthenium layer by being stacked. Can be.

The specific surface area of the aluminum oxide is 5 or more, specifically 50 or more, and more preferably 100 m ² /g or more.

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

The aluminum oxide is generally called alumina, and is colorless or white and does not dissolve in water. α alumina is a product of the Bayer method. Melting point 1999~202℃. β alumina is said to be stable at high temperatures (1,500°C or higher). γ alumina is obtained by heating and dehydrating a hydrate or α-hydrated alumina, and further maintaining it at 900° C., and has a characteristic of transitioning to α alumina when the temperature is 1,000° C. or higher.

The aluminum oxide exhibits a high specific surface area and good heat resistance against firing at an elevated temperature, and is therefore preferable for use as a catalyst support.

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

The zirconia is zirconium oxide (IV) ZrO ₂ and is usually used as a 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 corrosion resistance is large. It does not dissolve in water, but dissolves in sulfuric acid and hydrofluoric acid. Since it withstands rapid changes in temperature, it can be used for rapid heating and rapid cooling.

The titania is an oxide of titanium, and when absorbing external rays, oxygen in air or active oxygen having strong oxidizing power in water can be produced. 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 its natural state, silica has five or more homogeneous crystals (quartz, tridymite, cristobalite, coesite, stishovite), silver microcrystalline (chalcedony), amorphous and hydrated compounds (opal) And various other forms.

The zeolite is also referred to as a zeolite and has many types, but is common in that it has many water contents, crystal properties, and acid phase. Hardness does not exceed 6, and specific gravity is about 2.2. It is generally colorless transparent or white translucent. In addition, since the bond of each atom is loose in the crystal structure, even when the water filling the gap is released with high heat, the skeleton remains, so other fine particles can be adsorbed and used as a catalyst support.

According to an embodiment of the present invention, the Ir-based deNOx catalyst may provide that calcined for 1 to 10 hours at a temperature of 300 to 800°C under wet air.

The wet atmosphere firing temperature should be 300°C or higher to increase the NOx removal efficiency at low temperature, and the firing temperature should be 800°C or lower to provide the Ir-based deNOx catalyst with high NOx removal efficiency at low temperature.

When the calcination temperature exceeds 800° C., the catalyst component may volatilize, and the performance may decrease due to a decrease in the catalytic activity point by sintering. In addition, the above-described range is preferable because a problem of high energy consumption due to high temperature may occur.

The firing can be carried out under hydrogen, argon and air static pressure, but is preferably carried out under wet air.

When performing the firing in the hydrogen atmosphere, the catalyst structure is different and the removal of the precursor components is not easy, so it is preferable to perform the firing under wet air.

According to an embodiment of the present invention, the Ir-based deNOx catalyst may be any one selected from the group consisting of a group of TWC, LNT or SCR catalysts.

Ir-based deNOx catalyst according to an embodiment of the present invention, by firing for 1 to 10 hours at a temperature of 300 ~ 800 ℃ under wet air conditions, it is possible to form a catalyst with improved NOx removal efficiency at low temperatures.

Hereinafter, a method of manufacturing an Ir-based deNOx catalyst according to an embodiment of the present invention will be described in detail step by step with reference to FIG. 1.

Method for producing an Ir-based deNOx catalyst according to an embodiment of the present invention, (a) supporting a ruthenium on a support (S100); (B) step of supporting iridium on the support of step (a) (S200); And (c) calcining the iridium-supported support of step (b) under wet air (S300).

In the method of manufacturing an Ir-based deNOx catalyst according to an embodiment of the present invention, step (a) (S100) is (a) a step of supporting ruthenium on the support (S100).

According to an embodiment of the present invention, the support may be one selected from the group consisting of aluminum oxide, zirconia, titania, silica, zeolite, ceria, and ceria-based multi-component compounds, specifically aluminum oxide. . At this time, the support may be monolithized to be supported on the iridium and ruthenium precursor solution to form a catalyst layer.

In addition, the support may include a ruthenium layer and an iridium layer sequentially on a monolith, the ruthenium layer may be supported on the outer surface and inner pores of the support, and an iridium layer is formed on the ruthenium layer by being stacked. Can be.

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

When the specific surface area of the aluminum oxide as the support is less than 5, there is a disadvantage in that the activity of the catalyst is poor, and the above range is preferable.

The (a) the ruthenium (Ru) of the step (S100), with respect to 100 parts by weight of the support, may be supported by 0.1 to 10 parts by weight, preferably 1,5 parts by weight.

The carrying amount of the ruthenium is preferably in an appropriate range, but in order to sufficiently exhibit the purpose of increasing the removal efficiency of NOx at low temperature, it is preferable to be 0.1 to 10 parts by weight with respect to 100 parts by weight of the support.

When the ruthenium is contained less than 0.1, the effect of removing NOx in the exhaust gas is insignificant, and when the ruthenium is contained in excess of 10, the activity of iridium can be suppressed, and the above range is preferable.

After the step (a) (S100), the step (a) of the ruthenium-supported may further include the step of firing in a humid air for 1 to 10 hours at a temperature of 300 ~ 800 ℃.

After the step (a) (S100), the step of firing is carried out in order not to escape due to the support of ruthenium on the support.

In the step (a) (S100), the support is introduced into a ruthenium solution and supported, followed by firing at 300 to 800° C. for 1 to 10 hours to first prepare the ruthenium-supported support. Here, preferably, with respect to 100 parts by weight of the support, ruthenium may include 1.5 parts by weight.

The step (a) (S100) may further include a catalyst component in addition to ruthenium, and the preferred catalyst component may be one or more selected from the group consisting of platinum, rhodium, palladium and silver. Among these additional noble metals, platinum, rhodium and silver are particularly preferred. In this case, the amount of platinum, rhodium, and silver supported is preferably 0.1 to 10 parts by weight of platinum relative to 100 parts by weight of the support. In addition, the loading amount of rhodium and silver is also preferably 0.1 to 10 parts by weight, respectively, relative to 100 parts by weight of the support. In the same way as above, it is to prevent the deterioration of the properties of ruthenium as a main component while exerting the effect of supporting additional precious metals. Moreover, a plurality of these additional metals may be supported.

In the method of manufacturing an IR-based deNOx catalyst according to an embodiment of the present invention, step (b) (S200) is a step (S200) of supporting iridium on the support of step (a).

The step (b) (S200) is a step (S200) of supporting iridium on the support of step (a). Here, the loading amount of the iridium, the iridium with respect to 100 parts by weight of the support may include 0.1 to 10 parts by weight, specifically 1.5 parts by weight. 0.1% by weight of the iridium loading amount is a minimum loading amount to secure the activity of the catalyst. On the other hand, with respect to 10 parts by weight, the above-mentioned range is preferable because the improvement in activity is insignificant because it is not economically desirable even if it is loaded more than this.

The step (b) (S200) may further include a catalyst component in addition to iridium, and the preferred catalyst component may be one or more selected from the group consisting of platinum, rhodium, palladium and silver. Among these additional noble metals, platinum, rhodium and silver are particularly preferred. In this case, the amount of platinum, rhodium, and silver supported is preferably 0.1 to 10 parts by weight of platinum relative to 100 parts by weight of the support. In addition, the supported amounts of rhodium and silver are also preferably 0.1 to 10 parts by weight, respectively, relative to 100 parts by weight of the support. In the same way as above, it is to prevent the deterioration of the properties of iridium as a main component while exerting the effect of supporting additional precious metals. Moreover, a plurality of these additional metals may be supported.

In the method for producing an Ir-based deNOx catalyst according to an embodiment of the present invention, the step (c) (S300) is a step of firing the support containing the iridium of step (b) under wet air (S300). to be.

The step (c) (S300) may be performed for 1 to 10 hours at a temperature of 300 to 800° C. under wet air.

* If the firing temperature of step (c) (S300) is performed at 300°C or less, the low temperature activity of the final catalyst is deteriorated, and when the firing temperature is performed at 800°C or higher, catalyst components may be volatilized, The catalytic activity point decreases by sintering, and performance may decrease. In addition, energy consumption is high due to high temperature.

2 is a flow chart showing a method of manufacturing an Ir-based deNOX catalyst according to another embodiment of the present invention.

Method for producing an Ir-based deNOx catalyst according to another embodiment of the present invention, (a) preparing a mixture of ruthenium and iridium (S10); (b) supporting a ruthenium and iridium mixture on a support (S20); And (c) sintering the support on which ruthenium and iridium in step (b) are supported (S30).

The method of preparing the mixture of ruthenium and iridium in step (A) in step (S10) may be prepared by a conventional method, and therefore will not be described.

In addition, the reason for supporting the support on the ruthenium and iridium mixture is to prevent iridium from being first supported on the support. When iridium is first supported on the support, the synergistic effect of iridium and ruthenium cannot be expected due to the strong interaction between the iridium and the support. In addition, when the ruthenium and iridium are supported on the support, two components must be present in close proximity to expect a low-temperature performance enhancing effect.

The step (c) (S30) may be performed for 1 to 10 hours at a temperature of 300 to 800°C under wet air.

Conditions other than the above-described method are the same as the above-described method, so a description thereof will be omitted.

The manufacturing method of the Ir-based deNOx catalyst described above may be two methods of first supporting a ruthenium on the support and then supporting iridium and supporting a ruthenium and iridium mixture on the support.

Ir-based deNOx catalyst prepared according to an embodiment of the present invention, may be any one selected from the group consisting of a group of TWC, LNT or SCR catalyst.

According to an embodiment of the present invention, it is possible to provide a deNOx system including a process for removing Nox with the catalyst described above.

DeNOx system according to an embodiment of the present invention, a 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 reduction device disposed at the rear of the diesel particulate filter to decompose nitrogen oxides contained in exhaust gas, and the NOx reduction device is internally installed to remove nitrogen oxides of exhaust gas that has passed through the diesel particulate filter. At least one catalyst prepared according to the present invention may be disposed.

The use of the Ir-based deNOx catalyst and its manufacturing method according to the present invention has an advantage of increasing the removal efficiency of NOx present in the exhaust gas even at a low temperature of 180°C.

In addition, there is an economic advantage because a separate reducing agent injection device and a periodic external supply are not required to remove NOx present in the exhaust gas. In particular, it is possible to impart additional deNOx performance to LNT, DOC, or TWC outside the scope of the conventional urea SCR, and also to reduce CO and hydrocarbon.

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

Example 1: IrRu/Al ₂ O ₃ Preparation of catalyst 1

First, 0.190 g of IrCl3 sample and 0.193 g of RuCl3 sample were dissolved in water at the same time, and then supported on 5 g of γ-aluminum oxide, and then 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 prepare a catalyst (IrRu/Al ₂ O ₃ ) in which iridium-ruthenium was supported on aluminum oxide.

*

In this case, the supported amount of ruthenium of the catalyst is based on 100 parts by weight of the total catalyst, and the supported amount of ruthenium is 1.52 parts by weight, and the supported amount of iridium is 2.11 parts by weight.

Example 2: IrRu/Al ₂ O ₃ Preparation of catalyst 2

It was carried out in the same manner as in Example 1, but the firing temperature was set to 700°C and carried out for 4 hours.

Example 3: IrRu/Al ₂ O ₃ Preparation of catalyst 3

It was carried out in the same manner as in Example 1, but the firing temperature was set to 500°C and carried out in an argon atmosphere for 4 hours.

Example 4: IrRu/Al ₂ O ₃ Preparation of catalyst 4

It was carried out in the same manner as in Example 1, but the firing temperature was set to 700°C and carried out in an argon atmosphere for 4 hours.

Example 5: IrRu/Al ₂ O ₃ Preparation of catalyst 5

First, 0.193 g of a RuCl 3 sample was dissolved in water, and then supported on 5 g of γ-aluminum oxide, and then 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. After dissolving 0.190 g of IrCl ₃ sample in water, it was supported on the fired sample 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 (Ir-Ru/Al ₂ O ₃ ) catalyst.

In this case, the supported amount of ruthenium of the catalyst is based on 100 parts by weight of the total catalyst, and the supported amount of ruthenium is 1.52 parts by weight, and the supported amount of iridium is 2.11 parts by weight.

Comparative Example 1: IrRu/Al ₂ O ₃ Preparation of catalyst

It was carried out in the same manner as in Example 1, the firing temperature was set to 500 ℃ and carried out for 4 hours in a static air atmosphere.

Comparative Example 2: IrRu/Al ₂ O ₃ Preparation of catalyst

It was carried out in the same manner as in Example 1, the firing temperature was set to 700 ℃ and carried out for 4 hours in a static air atmosphere.

Comparative Example 3: IrRu/Al ₂ O ₃ Preparation of catalyst

It was carried out in the same manner as in Example 1, but the firing temperature was set to 500° C. and carried out in a hydrogen atmosphere for 4 hours.

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

It was carried out in the same manner as in Example 1, but the firing temperature was set to 700°C and carried out in a hydrogen atmosphere for 4 hours.

Comparative Example 5: IrRu/Al ₂ O ₃ Preparation of catalyst

* First, 0.190 g of IrCl3 sample was dissolved in water, and then supported on 5 g of γ-aluminum oxide, and then 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. After dissolving 0.193 g of RuCl ₃ sample in water, it was supported on a fired sample 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 (Ru-Ir/Al ₂ O ₃ ) catalyst.

In this case, the supported amount of ruthenium of the catalyst is based on 100 parts by weight of the total catalyst, and the supported amount of ruthenium is 1.52 parts by weight, and the supported amount of iridium is 2.11 parts by weight.

Experimental Example 1: Confirmation of nitrogen oxide removal according to the firing atmosphere

The catalysts prepared according to Examples 1 to 5 and Comparative Examples 1 to 4 were measured for nitrogen oxide removal activity under the following measurement conditions.

Nitric oxide (NO): 50 ppm

CO: 0.7%

O ₂ : 5%

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

<Evaluation>

3 is a comparison of nitrogen oxide removal activity of the catalysts prepared according to Examples 1 to 5 and Comparative Examples 1 to 4.

As a result, as shown in FIG. 3, the highest nitrogen oxide removal performance under wet air was observed at 500°C, and the high nitrogen oxide removal performance under wet air and argon was shown at 700°C. In particular, it was confirmed that the catalyst according to Example 1 exhibited the highest nitrogen oxide removal performance under the firing temperature conditions of 500 to 700°C. On the other hand, it was confirmed that the catalyst calcined in stagnant air or hydrogen atmosphere significantly reduced performance at low temperatures.

Accordingly, it was confirmed that the IrRu/Al ₂ O ₃ catalyst of Example 1, which is an Ir-based dxNOx catalyst according to the present invention, has an effect of improving the performance of removing nitrogen oxides present in exhaust gas at a low temperature of 180°C.

In addition, it can be confirmed that a separate reducing agent is not required to remove NOx present in the exhaust gas.

Experimental Example 2: Confirmation of nitrogen oxide removal according to loading order

Catalysts prepared according to Example 1, Example 5 and Comparative Example 5 were measured for nitrogen oxide removal activity under the following measurement conditions.

Nitric oxide (NO): 50 ppm

CO: 0.7%

O ₂ : 5%

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

<Evaluation>

4 is a comparison of nitrogen oxide removal activity according to the loading order of iridium and ruthenium of Example 1, Example 5 and Comparative Example 5.

As a result, as shown in FIG. 4, it was confirmed that the loading order affects the nitrogen oxide removal performance of the catalyst. According to Example 1, the performance is excellent when supported in a mixed solution of ruthenium and iridium, but according to Comparative Example 5, it was confirmed that the activity of the catalyst was lowered when iridium was first supported and then ruthenium was supported, whereas Example 5 According to the results, it was confirmed that the Ir-Ru/Al ₂ O ₃ catalyst loaded with iridium after ruthenium was supported showed high nitrogen oxide removal performance at around 180°C.

Accordingly, it was confirmed that the IrRu/Al ₂ O ₃ catalysts according to Examples 1 and 5, which are deNOx catalysts according to the present invention, had an effect of improving the nitrogen oxide removal performance existing in the exhaust gas at a low temperature of 180°C.

The use of the Ir-based deNOx catalyst and its manufacturing method according to the present invention has an advantage of increasing the removal efficiency of NOx present in the exhaust gas even at a low temperature of 180°C.

In addition, there is an economical advantage because it does not require the introduction of a separate reducing agent to remove the NOx present in the exhaust gas.

So far, specific examples of a method of manufacturing an Ir-based deNOx catalyst according to an embodiment of the present invention have been described, but it is apparent that various implementation modifications are possible 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 determined not only by the claims to be described later, but also by the claims and equivalents.

That is, the above-described embodiments are illustrative in all respects, and should be understood as not limiting, and the scope of the present invention is indicated by the claims to be described later rather than the detailed description, and the meaning and scope of the claims and It should be construed that any altered or modified form derived from the equivalent concept is included in the scope of the present invention.

S100: Step of supporting ruthenium on the support
S200: step of loading iridium on the support
S300: sintering the support on which iridium is supported under moist air
S10: Step of preparing a mixture of ruthenium and iridium
S20: Supporting a ruthenium and iridium mixture on a support
S30: Step of firing a support carrying ruthenium and iridium

Claims (10)

As a catalyst that reduces nitrogen oxides (NOx) by using CO in the exhaust gas as a reducing agent,
A mixture of iridium and ruthenium is supported on the support and fired in wet air,
As an Ir-based deNOx catalyst, which is primarily supported by ruthenium and secondaryly supported by iridium and fired under moist air,
With respect to 100 parts by weight of the support, the iridium is supported by 0.1 to 10 parts by weight, the ruthenium is Ir-based deNOx catalyst, characterized in that supported by 0.1 to 10 parts by weight.
delete delete According to claim 1,
The firing,
Ir-based deNOx catalyst, characterized in that calcined for 1 to 10 hours at a temperature of 300 to 800°C under moist air.
According to claim 1,
The support,
Ir-based deNOx catalyst, characterized in that it is aluminum oxide.
According to claim 1,
The Ir-based deNOx catalyst,
IrC deNOx catalyst, characterized in that any one selected from the group consisting of a group of TWC, LNT or SCR catalyst.
(a) preparing a mixture of ruthenium and iridium;
(b) supporting a ruthenium and iridium mixture on a support; And
(c) calcining the support containing the ruthenium and iridium of step (b) under wet air;
As a method for producing an Ir-based deNOx catalyst containing,
With respect to 100 parts by weight of the support, the iridium is supported by 0.1 to 10 parts by weight, and the ruthenium is 0.1 to 10 parts by weight of the method for producing an Ir-based deNOx catalyst.
The method of claim 7,
Step (c) is,
Method of producing an Ir-based deNOx catalyst characterized in that it is performed for 1 to 10 hours at a temperature of 300 to 800°C under wet air.
The method of claim 7,
The deNOx catalyst,
Method of producing an Ir-based deNOx catalyst, characterized in that any one selected from the group consisting of a group of TWC, LNT or SCR catalyst.
A deNOx system comprising the step of removing NOx with the catalyst according to any one of claims 1 and 4 to 6.

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