KR102226797B1 - Denox catalyst with improved nitrogen oxide reduction performance at high temperature, method for producing the same, and denox system using the same - Google Patents

Abstract

An object of the present invention is to provide a CO-SCR catalyst excellent in reducing nitrogen oxides at high temperature. In addition, it is an object of the present invention to provide a CO-SCR catalyst that has an excellent ability to reduce nitrogen oxides without using a noble metal-based active phase and thus has an effect of cost reduction.
The deNOx catalyst with improved nitrogen oxide reduction performance at high temperatures according to the present invention is a catalyst for reducing nitrogen oxides (NOx) using carbon monoxide (CO) in exhaust gas as a reducing agent, and includes a support on which barium (Ba) is supported. It is characterized.

Description

DeNOx catalyst with improved nitrogen oxide reduction performance at high temperature, its manufacturing method, and deNOx system using the same {DENOX CATALYST WITH IMPROVED NITROGEN OXIDE REDUCTION PERFORMANCE AT HIGH TEMPERATURE, METHOD FOR PRODUCING THE SAME, AND DENOX SYSTEM USING THE SAME}

The present invention relates to a deNOx catalyst having improved nitrogen oxide reduction performance at high temperature, a method for producing the same, and a deNOx system using the same, and more particularly, there is no need to use a noble metal-based active ingredient, so there is an effect of cost reduction and It provides a deNOx catalyst with improved nitrogen oxide reduction performance, a manufacturing method thereof, and a deNOx system using the same.

Nitrogen Oxide (NOx) is a material produced during the combustion process and is mostly generated in industrial processes and automobiles that require a combustion reaction. Nitrogen oxides cause respiratory diseases during human breathing, and react with hydrocarbons (HC) to form photochemical oxidants, causing photochemical smog and acid rain.

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 and the like, and the biggest damage is related to the generation of photochemical smog, which reacts with hydrocarbons in the presence of sunlight to produce photochemical oxides. In addition, this is converted into nitric acid and nitrate, which are the causes of acid rain, as well as visibility disorder and greenhouse effect, and it is estimated that about 40% of acid rain is caused by nitric acid. In addition, since hemoglobin _{has a strong adsorption capacity of 20,000 times to O 2} , it is known as a material that can cause great harm when the concentration is increased, and efforts to reduce it are urgently requested.

Among these emissions, the automobile portion accounts for about half of the emissions, and among them, it is reported that the emission of nitrogen oxides from diesel cars is higher than that of gasoline cars due to combustion characteristics. _{In addition, interest in reducing carbon dioxide (CO 2} ) is increasing due to the recent global warming problem, and among them, the method of using a diesel vehicle is drawing attention as the most effective GHG reduction countermeasure so far. This is because diesel vehicles have the characteristics of low _{CO 2} emissions by about 20-30% compared to gasoline vehicles.

In Korea, the preference for diesel engines is increasing due to the advantage of being able to obtain high fuel efficiency and low fuel cost compared to gasoline. In addition, in recent years, the vibration part, which was pointed out as a disadvantage of diesel engines, has been greatly improved, and the demand for diesel engines for RV cars is increasing due to the increase in interest in leisure ships. While the demand for vehicles using diesel engines is expected to increase for the preceding reasons, internationally, regulations on automobile emission standards such as EURO in the EU and ULEV in the US have been enacted, and the nitrogen oxide regulation is getting stronger.

As a method for treating such nitrogen oxides, there are largely a treatment method by engine technology and a treatment method by post-treatment technology. As for engine technology, first, a method of controlling fuel/air mixing and combustion generation by changing the combustion chamber structure, second, a method of fuel supply system such as injection pressure control, electronic control technology, and atomization technology, and third, intake air. There are methods of the supercharging system to prevent the temperature decrease in the air, and finally, methods of recirculating the exhaust gas to remove it. However, due to the reinforcement of the exhaust gas regulation, the application of post-treatment technology has become inevitable as there is a limit to satisfying the regulation with the reduction technology inside the engine.

As a post-treatment technology, a three-way catalyst (TWC), a method for reducing nitrogen oxides along with carbon monoxide and hydrocarbons by controlling the air-fuel ratio, uses a Lean NOx catalyst that selectively reduces nitrogen oxides by using hydrocarbons as a reducing agent. There is a method, a selective catalyst reduction (SCR) method in which nitrogen oxides are reduced to nitrogen and water using ammonia.

However, in the case of three-way catalyst, acceleration and deceleration operation must be performed during the operation of the vehicle, and even in the case of constant speed operation, since the speed and load conditions vary widely, there is a disadvantage that a difficult air-fuel ratio is required depending on the engine operating condition. In addition, the Lean NOx catalyst has a problem of low reduction efficiency.

_{NH 3} -SCR, which uses ammonia as a reducing agent, is effective in removing nitrogen oxides emitted from large-scale boilers and can be used even when the oxygen content is high, but it is difficult to apply to vehicles. For this, HC-SCR using hydrocarbons under high oxygen content has been studied a lot. Mainly zeolite, metal oxide and noble metal catalyst have been used, but they have not yet obtained sufficient performance for commercialization.

Therefore, as a way to overcome such a problem, it has been recently discovered that carbon monoxide can be an effective reducing agent. SCR technology using carbon monoxide as a reducing agent (hereinafter referred to as CO-SCR) was first reported by Tauster and Murrell in 1976. They tested 0.1% Ir/Al ₂ O ₃ to obtain a high NO conversion rate, and this catalyst plays a role in making the reaction with CO more dominant than the reaction _{of NO with O 2.}

On the other hand, the activity of the Ir catalyst for CO-SCR can be greatly improved by additives. Haneda et al. screened 19 metal elements and used Li, Na, Mg, Sr, Ba, W, Co, Ce, It was confirmed that the catalytic activity was increased when Zn, Pt, Rh, Au, and Ru _{were doped into Ir/SiO 2.} In particular, it was found that doping with Ba significantly increases the catalytic activity.

However, the SCR catalyst carrying a noble metal-based active ingredient such as Ir is expensive, and there is a problem in that the activity decreases at medium to high temperatures of 400°C or higher. Accordingly, the inventors of the present invention have been trying to solve the above problems, and the SCR catalyst, which does not use noble metal-based active ingredients, and supports barium itself as an active ingredient rather than an additive, can effectively reduce nitrogen oxides at medium and high temperatures. It was confirmed that the present invention was completed.

Republic of Korea Patent Publication No. 10-0654885 (announced on December 6, 2006)

An object of the present invention is to provide a catalyst that can be used for CO-SCR and has excellent ability to reduce nitrogen oxides at high temperatures and a method for producing the same.

In addition, an object of the present invention is to provide a CO-SCR catalyst and a method for producing the same, which is excellent in reducing nitrogen oxides without the use of noble metal-based active ingredients and thus has an effect of reducing cost.

In addition, an object of the present invention is to provide a deNOx system for removing nitrogen oxides using a catalyst having excellent nitrogen oxide reduction performance at high temperatures.

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.

The present invention is a catalyst for reducing nitrogen oxides (NOx) using carbon monoxide (CO) in exhaust gas as a reducing agent, and a deNOx catalyst having improved nitrogen oxide reduction performance at high temperatures, characterized in that it includes a support supported with barium (Ba). Provides.

The barium may be supported in an amount of 5 to 25 parts by weight based on 100 parts by weight of the support.

The support may be one or more selected from the group consisting of silicon, glass, alumina, zirconia, titania, ceria, and vanadia.

The conversion rate of nitrogen oxide using the catalyst may be 30 to 60% at a reaction temperature of 300 to 500 °C.

In addition, the present invention comprises the steps of (a) dissolving a barium compound in distilled water to prepare an aqueous solution; (b) preparing an aqueous solution containing a support by mixing a support with the aqueous solution; (c) drying the support-containing aqueous solution; And (d) calcining the resultant dried in step (c) to prepare a catalyst in which barium (Ba) is supported on the support. Provides a manufacturing method.

The barium compound in step (a) may be any one selected from the group consisting of barium sulfate, barium nitrate, barium acetate, barium chloride, or a combination thereof.

The support in step (b) may be one or more selected from the group consisting of silicon, glass, alumina, zirconia, titania, ceria, and vanadia.

The drying in step (c) may be performed at 80 to 120° C. for 1 to 24 hours.

The sintering of step (d) may be performed for 1 to 5 hours at a temperature of 300 to 700° C. in an air atmosphere.

In the step (d), the barium may be supported in an amount of 5 to 25 parts by weight based on 100 parts by weight of the support.

In addition, the present invention is a deNOx system that uses carbon monoxide (CO) in exhaust gas as a reducing agent to reduce nitrogen oxides by a catalyst including a support on which barium (Ba) is supported, wherein the barium is 5 parts by weight per 100 parts by weight of the support. It is supported in ~25 parts by weight, and the support is at least one selected from the group consisting of silicon, glass, alumina, zirconia, titania, ceria, and vanadia. to provide.

The conversion rate of nitrogen oxide using the catalyst may be 30 to 60% at a reaction temperature of 300 to 500 °C.

When the deNOx catalyst having improved nitrogen oxide reduction performance at high temperatures according to the present invention is used, there is an advantage of being able to effectively remove nitrogen oxides present in exhaust gas at medium and high temperatures.

In addition, when the deNOx catalyst having improved nitrogen oxide reduction performance at high temperature according to the present invention is used, there is an advantage that carbon monoxide in exhaust gas can be reduced together with nitrogen oxide removal.

In addition, according to the present invention, nitrogen oxides can be removed without the use of noble metal-based active ingredients, thereby reducing cost.

1 is a process flow chart showing a method of manufacturing a deNOx catalyst having improved nitrogen oxide reduction performance at a high temperature according to an embodiment of the present invention.
2 is a graph measuring the nitrogen oxide removal performance of catalysts prepared according to Example 1 and Comparative Examples 1 to 4 by temperature.
3 is a graph measuring carbon monoxide removal performance of catalysts prepared according to Example 1 and Comparative Examples 1 to 4 by temperature.
4 is a graph measuring the nitrogen oxide removal performance of catalysts prepared according to Examples 1 to 3 for each temperature.
5 is a graph measuring carbon monoxide removal performance of catalysts prepared according to Examples 1 to 3 for each temperature.
6 is a graph measuring the nitrogen oxide removal performance of catalysts prepared according to Example 1 and Comparative Example 5 for each temperature.
7 is a graph measuring carbon monoxide removal performance of catalysts prepared according to Example 1 and Comparative Example 5 by temperature.

In the following description, it should be noted that only parts necessary for understanding the embodiments of the present invention will be described, and descriptions of other parts will be omitted without distracting the gist of the present invention.

Terms or words used in the present specification and claims described below should not be construed as being limited to a conventional or dictionary meaning, and the inventor is appropriate as a concept of terms in order to describe his own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention on the basis of the principle that it can be defined as such.

Therefore, the embodiments described in the present specification and the configurations shown in the drawings are only preferred embodiments of the present invention, and do not represent all the technical spirit of the present invention, and various equivalents that can replace them at the time of application It should be understood that there may be variations and variations.

Hereinafter, the present invention will be described with reference to the drawings.

The deNOx catalyst with improved nitrogen oxide reduction performance at high temperatures according to an embodiment of the present invention is a catalyst for reducing nitrogen oxides (NOx) using carbon monoxide (CO) in exhaust gas as a reducing agent, and a support on which barium (Ba) is supported It characterized in that it comprises a.

The SCR system is a technology for removing nitrogen oxides in exhaust gas generated during operation of onshore plants, ships and automobiles. That is, SCR is used to reduce nitrogen oxides in exhaust gas generated from ship engines or boilers, or from boilers or incinerators of onshore plants. The SCR system is one of the nitrogen oxide reduction systems using the selective catalytic reduction method, and is configured to react with the nitrogen oxide and the reducing agent while simultaneously passing the exhaust gas and the reducing agent through the catalyst to reduce it to nitrogen and water vapor.

In general, the SCR system uses ammonia or urea providing ammonia as a reducing agent for reducing nitrogen oxides, and uses a catalyst having an active temperature range of 200°C to 400°C.

However, the deNOx catalyst having improved nitrogen oxide reduction performance at a high temperature according to an embodiment of the present invention uses carbon monoxide (CO) in exhaust gas as a reducing agent to remove nitrogen oxides. The exhaust gas of the combustion engine may include hydrocarbons, carbon monoxide, carbon dioxide, hydrogen, nitrogen, oxygen, sulfur oxides, and water in addition to nitrogen oxides.

When carbon monoxide in the exhaust gas is used as a reducing agent, there is no need for an auxiliary system such as a container for storing urea and an injection device in the related art, so that the space in the combustion engine can be utilized and there is no additional cost, so there is an economic advantage. In addition, there is an advantage in that carbon monoxide in exhaust gas can be removed at the same time as reducing nitrogen oxides.

Examples of nitrogen oxides removed according to the present invention include nitrogen monoxide, nitrogen dioxide, dinitrogen trioxide, dinitrogen tetraoxide, dinitrogen monoxide, and mixtures thereof. Preferably, they are nitrogen monoxide, nitrogen dioxide, and dinitrogen monoxide. The nitrogen oxide concentration in the exhaust gas that can be treated by the present invention is not limited.

The deNOx catalyst having improved nitrogen oxide reduction performance at a high temperature according to an embodiment of the present invention includes a support on which barium (Ba) is supported.

Barium is an element with atomic number 56, and the element symbol is Ba. It belongs to the alkaline earth metal group, which is Group 2 (Group 2A) along with beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), and radium (Ra) in the periodic table. Chemically similar to calcium or strontium, but more reactive than these. It is a silvery white, soft metal. When exposed to air, it easily reacts with oxygen and is oxidized. It also reacts with water and alcohol _{to generate hydrogen (H 2} ) gas. Therefore, barium metal should be stored under an inert gas or mineral oil such as petroleum while air is blocked. When burned in air or oxygen, it burns with a light yellow-green flame and _{becomes barium oxide (BaO) and barium peroxide (BaO 2} ). It reacts with most non-metallic elements and is well soluble in most acids except sulfuric acid. The oxidation state in the compound is mainly +2.

Because barium is highly reactive, it is found only as a compound in its natural state. The abundance ratio in the crust is about 390 ppm (0.039%), the 14th most abundant element, slightly more than sulfur (S) or strontium (Sr) and slightly less than fluorine (F). It is dissolved in seawater at 13 μg/L, which is about 1/600 of strontium. Barite ( _{BaSO 4} ) is the most common ore from which barium is produced, and a small amount is also produced from _{witherite (BaCO 3 ).} Metal barium is obtained by reducing barium oxide (BaO) to aluminum (Al) or silicon (Si), or by electrolyzing barium chloride (BaCl ₂ ), but the amount produced as metal barium is not large.

Barium may be supported in an amount of 5 to 25 parts by weight based on 100 parts by weight of the support.

The 5 parts by weight of barium supported is the minimum supported amount for securing the activity of the catalyst, and when the amount exceeds 25 parts by weight, the activity of the catalyst becomes rather insignificant, so economic loss may occur, and thus the above range is preferable.

The support widely distributes the active ingredients of the catalyst and promotes the catalytic reaction through interaction.

The support according to an embodiment of the present invention It may be made of one or more selected from the group consisting of silicon, glass, alumina, zirconia, titania, ceria, and vanadia, preferably alumina.

Alumina (Al ₂ O ₃ ) is structurally stable and can be manufactured by varying the pore size and distribution widely, and also participates in the catalytic reaction because it has a weak acid point, and the dispersibility of the metal is better than that of the silica support, It has excellent physical and mechanical properties to have as a support. Al ₂ O ₃ includes low-temperature transition alumina such as κ, χ, ρ, η, γ, δ, and high-temperature transition alumina such as θ, α, and β. However, in the present invention, it is preferable to use _{γ-Al 2} O ₃ or α-Al ₂ O _3.

In order to support barium on the support, an impregnation method, a precipitation method, or an ion exchange method may be used.

The impregnation method includes adsorption method, evaporation drying method, spray method, and incipient wetness method depending on the contact method.

The adsorption method is a method in which a support is immersed in a solution in which the active ingredient is dissolved, and the active ingredient is adsorbed and supported on the surface of the support.

The evaporation drying method is a method in which the active ingredient is attached to the support by immersing the support in a solution in which the active ingredient is dissolved, and then the solvent is evaporated.This has a disadvantage that the pores can be clogged if the amount of active ingredient is large and the pores of the support are thin and large.

The spraying method is a method in which a solution containing an active ingredient is sprayed and supported by putting the support in an evaporator and shaking. The active ingredient sticks to the surface rather than the pores.

The initial wet impregnation method is the most widely used method, and is a method of removing the solvent by adding a solution in which an active material is dissolved in a solvent as much as the pore volume of the support to a dried support, and then drying it to remove the solvent.

In the precipitation method, when a precipitant is added to the aqueous solution of the active ingredient, the product of the ion concentration becomes larger than the solubility product depending on the precipitation component, thereby generating a precipitated nucleus and growing the nucleus to generate a precipitate. The supported catalyst prepared by this method is a method of simultaneously precipitating the supported component from the solution by coprecipitation, mixing the precipitation of the catalytically active component with the support, and adding a precipitant solution after immersing the support in the catalyst component solution to activate it on the support. It is prepared by a method of precipitating the component.

The ion exchange method is a method of supporting a cation as an active ingredient by ion exchange, and is widely used when metal ions are supported on zeolite, silica, and silica-alumina.

The ion exchange method has the advantage that the active ingredient is distributed very uniformly, the interaction between the metal precursor and the support is strong, and the degree of ion exchange is determined by the components of the support and the pH of the solution. In general, the ion exchange reaction proceeds in two continuous steps, such as ion diffusion and ion exchange to the surface of the support. Therefore, when the pore size of the support is small, the total ion exchange rate is determined by the diffusion rate. In addition, if the amount of ions to be exchanged in the aqueous solution is smaller than the amount of exchange points present in the support, the ion exchange proceeds only to the outer portion of the support, so that a uniform distribution cannot be obtained. Therefore, in this case, it must be supported for a long time, and the ion-exchanged material must be washed, dried, and fired. Washing is a process for removing impurities left in the support during the ion exchange process. In the drying process, since the interaction between the metal precursor and the support is strong, there is little change in the catalyst. In the firing process, the sintering of the metal occurs very slowly, and depending on the firing conditions, the structure of the final catalyst is affected.

It is preferable that the deNOx catalyst having improved nitrogen oxide reduction performance at a high temperature according to an embodiment of the present invention is prepared through a wet impregnation method among the above methods.

Specifically, after preparing a support-containing aqueous solution by mixing a support with an aqueous solution in which a barium compound is dissolved in distilled water, the support-containing aqueous solution may be dried and then calcined.

First, the barium compound is dissolved in distilled water.

The barium compound may be specifically barium sulfate, barium nitrate, barium acetate, barium chloride, or a combination thereof.

Next, a support is mixed with the aqueous solution to prepare an aqueous solution containing a support.

The aqueous solution containing the support is dried at a temperature of 80 to 120°C. When the aqueous solution containing the support is dried at a temperature of less than 80° C., there may be too much moisture remaining, and when the aqueous solution is dried above 120° C., pores on the surface of the support are combined and the surface area may be reduced.

The drying may be performed for 1 to 24 hours.

Finally, the dried product is calcined to prepare a deNOx catalyst.

The dried result may be calcined for 1 to 5 hours at a temperature of 300 to 700 °C in an air atmosphere. At this time, if the sintering temperature is too low below 300 ℃, impurities remaining after the formation of the catalyst are not properly removed, so the activity of the catalyst decreases. If the sintering temperature exceeds 700 ℃, durability due to a change in the phase of the support. This can be degraded.

The deNOx catalyst having improved nitrogen oxide reduction performance at high temperature according to an embodiment of the present invention may further include a binder and/or a dispersant.

The binder is, for example, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyurethane (PU), polyether urethane, polyurethane copolymer, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate , Polymethyl methacrylate (PMMA), polymethyl acrylate (PMA), polyacrylic copolymer, polyvinyl acetate (PVAc), polyvinyl acetate copolymer, polyperfuryl alcohol (PPFA), polystyrene (PS), polystyrene Copolymer, polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene oxide copolymer, polypropylene oxide copolymer, polycarbonate (PC), polyvinyl chloride (PVC), polycaprolactone (PCL), polyvinylidene Fluoride (PVDF), polyvinylidene fluoride copolymer, and polyamide.

Examples of the dispersant include polyacrylic acid, polymethacrylic acid, pyrophosphoric acid, citric acid, polymalic acid, ammonium polymethacrylate, benzoic acid, catechol, pyrogallol, and the like.

The binder functions to improve adhesion so that the coating layer can be well adhered to the substrate, and the dispersant allows such binder particles to be well dispersed as a whole.

The conversion rate of nitrogen oxides using a deNOx catalyst having improved nitrogen oxide reduction performance at a high temperature according to an embodiment of the present invention may be 30 to 60% at a reaction temperature of 300 to 500°C.

Hereinafter, a method of manufacturing a deNOx catalyst having improved nitrogen oxide reduction performance at a high temperature according to an embodiment of the present invention will be described in detail step by step with reference to FIG. 1.

1 is a process flow chart showing a method of manufacturing a deNOx catalyst having improved nitrogen oxide reduction performance at a high temperature according to an embodiment of the present invention.

A method of preparing a deNOx catalyst having improved nitrogen oxide reduction performance at a high temperature according to an embodiment of the present invention includes the steps of: (a) dissolving a barium compound in distilled water; (b) forming an aqueous solution containing a support by mixing a support with the aqueous solution; (c) drying the support-containing aqueous solution; And (d) firing the dried product to form a deNOx catalyst.

First, the barium compound is dissolved in distilled water (S100).

The barium compound may be specifically barium sulfate, barium nitrate, barium acetate, barium chloride, or a combination thereof.

Next, a support is mixed with the aqueous solution to form an aqueous solution containing a support (S200).

The support widely distributes the active ingredients of the catalyst and promotes the catalytic reaction through interaction.

The support according to an embodiment of the present invention It may be made of one or more selected from the group consisting of silicon, glass, alumina, zirconia, titania, ceria, and vanadia, preferably alumina.

Alumina (Al ₂ O ₃ ) is structurally stable and can be manufactured by varying the pore size and distribution widely, and also participates in the catalytic reaction because it has a weak acid point, and the dispersibility of the metal is better than that of the silica support, It has excellent physical and mechanical properties to have as a support. Al ₂ O ₃ includes low-temperature transition alumina such as κ, χ, ρ, η, γ, δ, and high-temperature transition alumina such as θ, α, and β. It goes crazy, among which it is preferable to use _{γ-Al 2} O ₃ and α-Al ₂ O _3.

The barium may be supported in an amount of 5 to 25 parts by weight based on 100 parts by weight of the support. The 5 parts by weight of barium supported is the minimum supported amount for securing the activity of the catalyst, and when the amount exceeds 25 parts by weight, the activity of the catalyst is rather insignificant and economic loss may occur, so the above range is preferable.

Finally, the aqueous solution containing the support is dried and calcined to form a deNOx catalyst (S300 to S400).

The aqueous solution containing the support may be dried at a temperature of 80 to 120 °C.

When the aqueous solution containing the support is dried at a temperature of less than 80° C., there may be too much moisture remaining, and when the aqueous solution is dried at a temperature exceeding 120° C., pores on the surface of the support are combined and the surface area may be reduced.

The drying may be performed for 1 to 24 hours.

The dried result may be calcined for 1 to 5 hours at a temperature of 300 to 700 °C in an air atmosphere.

At this time, if the sintering temperature is too low (below 300°C), impurities remaining after the catalyst are formed may not be properly removed, resulting in a decrease in the activity of the catalyst. It can be degraded.

According to another aspect of the present invention, the present invention provides a deNOx system using a deNOx catalyst having improved nitrogen oxide reduction performance at high temperatures.

The deNOx system may purify nitrogen oxides from exhaust gases from diesel vehicles and gasoline vehicles, and from various exhaust gases emitted from boilers and gas turbines.

According to the deNOx system according to the present invention, there is an advantage of improving the removal performance of nitrogen oxides present in exhaust gas at medium to high temperatures of 300° C. or higher, and cost reduction because nitrogen oxides can be removed without the use of noble metal-based active ingredients. Has the effect of.

In addition, there is an advantage in that carbon monoxide in exhaust gas can be reduced together with nitrogen oxide removal.

Example

Hereinafter, the present invention will be described in more detail by examples and experimental examples. However, the following Examples and Experimental Examples are for illustrative purposes only, and the scope of the present invention is not limited thereto.

Example 1: 20 Ba/Al ₂ O ₃ Preparation of catalyst

First, 1.86 g of barium acetate was dissolved in 200 ml of distilled water, and then barium was supported in 5 g of γ-alumina through a wet impregnation method. The obtained sample was dried at 105° C. for 12 hours, and the dried sample was calcined at 500° C. for 4 hours in an air atmosphere to prepare a 20 Ba/Al ₂ O ₃ catalyst in which barium was supported on alumina. At this time, barium was supported in 20 parts by weight based on 100 parts by weight of the alumina support.

Example 2: 10 Ba/Al ₂ O ₃ Preparation of catalyst

Next, 0.93 g of barium acetate was dissolved in 200 ml of distilled water, and then barium was supported in 5 g of γ-alumina through a wet impregnation method. Subsequent steps were carried out in the same manner as in Example 1 to prepare a 10 Ba/Al ₂ O ₃ catalyst in which barium was supported on alumina. At this time, 10 parts by weight of barium was supported based on 100 parts by weight of the alumina support.

Example 3: 30 Ba/Al ₂ O ₃ Preparation of catalyst

Next, 2.79 g of barium acetate was dissolved in 200 ml of distilled water, and then barium was supported in 5 g of γ-alumina through a wet impregnation method. Subsequent steps were carried out in the same manner as in Example 1 to prepare a 30 Ba/Al ₂ O ₃ catalyst in which barium was supported on alumina. At this time, 30 parts by weight of barium was supported based on 100 parts by weight of the alumina support.

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

After dissolving 0.72 g of potassium acetate in 200 ml of distilled water, potassium was supported in 5 g of γ-alumina through a wet impregnation method. Subsequent steps were carried out in the same manner as in Example 1 to prepare a K/Al ₂ O ₃ catalyst in which potassium was supported on alumina. At this time, 5.7 parts by weight of potassium was supported based on 100 parts by weight of the alumina support.

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

After 1.04 g of magnesium acetate was dissolved in 200 ml of distilled water, magnesium was supported in 5 g of γ-alumina through a wet impregnation method. Subsequent steps were carried out in the same manner as in Example 1 to prepare a Mg/Al ₂ O ₃ catalyst in which magnesium was supported on alumina. At this time, 3.5 parts by weight of magnesium was supported based on 100 parts by weight of the alumina support.

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

1.15 g of calcium acetate was dissolved in 200 ml of distilled water, and then calcium was supported in 5 g of γ-alumina through a wet impregnation method. Subsequent steps were carried out in the same manner as in Example 1 to prepare a Ca/Al ₂ O ₃ catalyst in which calcium was supported on alumina. At this time, calcium was supported at 5.8 parts by weight based on 100 parts by weight of the alumina support.

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

After dissolving 1.5 g of strontium acetate in 200 ml of distilled water, strontium was supported in 5 g of γ-alumina through a wet impregnation method. Subsequent steps were carried out in the same manner as in Example 1 to prepare a Sr/Al ₂ O ₃ catalyst in which calcium was supported on alumina. At this time, 12.7 parts by weight of strontium was supported based on 100 parts by weight of the alumina support.

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

First, 0.19 g of iridium chloride (Iridium Chloride, IrCl ₃ ) and 0.193 g of ruthenium chloride (Ruthenium Chloride, RuCl ₃ ) were dissolved in 200 ml of distilled water, and then supported in 5 g of γ-alumina through a wet impregnation method. Thereafter, the supported sample was dried at 105° C. for 12 hours, and the obtained sample was calcined for 4 hours at 500° C. in humid air to prepare an IrRu/Al ₂ O ₃ catalyst in which iridium-ruthenium was supported on alumina.

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

Experimental Example 1: Confirmation of nitrogen oxide and carbon monoxide removal performance according to supported metal active ingredients

For the catalysts prepared according to Example 1 and Comparative Examples 1 to 4, the nitrogen oxide and carbon monoxide removal performance were measured for each temperature under the following measurement conditions.

Nitrogen oxide (NO): 50 ppm

CO: 7000 ppm

O ₂ : 5%

N ₂ balance

Total flow: 200 ml/min

After 0.1 g of a sieving (sieving) catalyst with a particle size of 180 to 250 μm was charged into a quartz reactor, a reduction pretreatment was performed to activate the catalyst before the reaction. In the pretreatment process, _{a mixed gas containing 10% H 2} gas (flow rate: 200 ml/min, N ₂ balance) was allowed to pass through the catalyst layer, and the temperature of the reactor was set to 450° C. to perform the pretreatment process for 1 hour.

Thereafter, the temperature of the reactor was lowered to room temperature, and nitrogen gas and reactants such as NO, CO, and O ₂ were allowed to pass through the catalyst layer to perform a nitrogen oxide removal reaction. In this experimental example, the conversion rate of nitrogen oxide and carbon monoxide was calculated through the following equation.

[Equation 1]

[X] ₀ : Concentration of species X when injecting the reactor

[X]: Concentration of species X when discharged from the reactor

<Evaluation>

2 is a graph measuring the nitrogen oxide removal performance of catalysts prepared according to Example 1 and Comparative Examples 1 to 4 by temperature, and FIG. 3 is a graph of carbon monoxide removal from catalysts prepared according to Example 1 and Comparative Examples 1 to 4 This is a graph measuring performance by temperature.

2 and 3, the catalysts prepared according to Comparative Examples 1 to 4 showed generally poor nitrogen oxide and carbon monoxide conversion rates, and the conversion rate did not exceed 50% even at a high temperature of 400° C. or higher.

However, the 20 Ba/Al ₂ O ₃ catalyst prepared according to Example 1 exhibited activity in the range of 350 to 450° C., and it was confirmed that the nitrogen oxide conversion rate was 50% or more at 400° C. or higher. Accordingly, it was confirmed that the barium-supported catalyst has superior nitrogen oxide and carbon monoxide reduction performance compared to the catalysts supporting other alkali metal and alkaline earth metal active ingredients.

Experimental Example 2: Measurement of nitrogen oxide and carbon monoxide removal performance depending on the amount of barium supported

The nitrogen oxide and carbon monoxide removal performance of the catalysts prepared according to Examples 1 to 3 were measured.

Nitrogen oxide (NO): 50 ppm

CO: 7000 ppm

O ₂ : 5%

N ₂ balance

Total flow: 200 ml/min

After 0.1 g of a sieving (sieving) catalyst with a particle size of 180 to 250 μm was charged into a quartz reactor, a reduction pretreatment was performed to activate the catalyst before the reaction. In the pretreatment process, _{a mixed gas containing 10% H 2} gas (flow rate: 200 ml/min, N ₂ balance) was allowed to pass through the catalyst layer, and the temperature of the reactor was set to 450° C. to perform the pretreatment process for 1 hour.

Thereafter, the temperature of the reactor was lowered to room temperature, and nitrogen gas and reactants such as NO, CO, and O ₂ were allowed to pass through the catalyst layer to perform a nitrogen oxide removal reaction. In this experimental example, the conversion rate of nitrogen oxide and carbon monoxide was calculated through the following equation.

[Equation 1]

[X] ₀ : Concentration of species X when injecting the reactor

[X]: Concentration of species X when discharged from the reactor

<Evaluation>

4 is a graph measuring the nitrogen oxide removal performance of the catalysts prepared according to Examples 1 to 3 by temperature, and FIG. 5 is a graph measuring the carbon monoxide removal performance of the catalysts prepared according to Examples 1 to 3 by temperature. .

4 and 5, the catalyst prepared according to Example 3 showed a relatively poor conversion rate compared to the catalyst prepared according to Examples 1 and 2. In addition, the catalyst prepared according to Example 3 showed a tendency that the conversion rate of nitrogen oxides and carbon monoxide gradually increased as the temperature increased to 500°C, but the catalysts prepared according to Examples 1 and 2 had rapid activity at 300 to 400°C. It was confirmed that the conversion rate at high temperature at 400° C. was close to 50%, showing excellent conversion rate.

Accordingly, it was found that the conversion rate of nitrogen oxide and carbon monoxide did not increase as the amount of barium supported increased, and an optimal amount of barium supported that could increase the removal performance of nitrogen oxide and carbon monoxide exists.

Experimental Example 3: Comparison of nitrogen oxide and carbon monoxide removal performance according to the presence or absence of a noble metal active ingredient

The nitrogen oxide and carbon monoxide removal performance of the catalyst prepared according to Example 1 and the catalyst including the noble metal active phase prepared according to Comparative Example 5 were measured and compared.

Nitrogen oxide (NO): 50 ppm

CO: 7000 ppm

O ₂ : 5%

N ₂ balance

Total flow: 200 ml/min

After 0.1 g of a sieving (sieving) catalyst with a particle size of 180 to 250 μm was charged into a quartz reactor, a reduction pretreatment was performed to activate the catalyst before the reaction. In the pretreatment process, _{a mixed gas containing 10% H 2} gas (flow rate: 200 ml/min, N ₂ balance) was allowed to pass through the catalyst layer, and the temperature of the reactor was set to 450° C. to perform the pretreatment process for 1 hour.

Thereafter, the temperature of the reactor was lowered to room temperature, and nitrogen gas and reactants such as NO, CO, and O ₂ were allowed to pass through the catalyst layer to perform a nitrogen oxide removal reaction. In this experimental example, the conversion rate of nitrogen oxide and carbon monoxide was calculated through the following equation.

[Equation 1]

[X] ₀ : Concentration of species X at the inlet of the reactor

[X]: Concentration of species X at the outlet of the reactor

<Evaluation>

6 is a graph measuring the nitrogen oxide removal performance of the catalysts prepared according to Example 1 and Comparative Example 5 by temperature, and FIG. 7 is a graph showing the carbon monoxide removal performance of the catalysts prepared according to Example 1 and Comparative Example 5 by temperature. It is a measured graph.

6 and 7, the catalyst containing the Ir and Ru noble metal active phase prepared according to Comparative Example 6 shows high nitrogen oxide and carbon monoxide conversion rates at a low temperature of 250° C. or less, but rapid deactivation of the conversion rate at a temperature of 300° C. or higher. Appears.

On the other hand, the catalyst prepared by Example 1 exhibited a high conversion rate at 300°C or higher, and it was found that the catalyst supporting barium is effective in increasing the nitrogen oxide removal rate at a relatively high temperature compared to the catalyst supporting Ir/Ru. I can.

Until now, a deNOx catalyst having improved nitrogen oxide reduction performance at a high temperature according to an embodiment of the present invention, a method for producing the same, and specific examples of a deNOx system using the same have been described, but within the limit not departing from the scope of the present invention. It is obvious that several implementation variations are possible.

Therefore, the scope of the present invention should not be defined by being limited to the described embodiments, and should be defined by the claims and equivalents as well as the claims to be described later.

That is, it should be understood that the above-described embodiments are illustrative in all respects and 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 All changes or modified forms derived from the equivalent concept should be construed as being included in the scope of the present invention.

Claims (12)

delete delete delete delete (a) dissolving a barium compound in distilled water to prepare an aqueous solution;
(b) preparing an aqueous solution containing a support by mixing a support with the aqueous solution;
(c) drying the support-containing aqueous solution; And
(d) preparing a catalyst in which barium (Ba) is supported on the support by sintering the resultant dried in step (c),
The support in step (b) is at least one selected from the group consisting of silicon, glass, alumina, zirconia, titania, ceria, and vanadia,
A method for producing a deNOx catalyst having improved nitrogen oxide reduction performance at high temperature, characterized in that the conversion rate of nitrogen oxides (NOx) is 30 to 60% at a reaction temperature of 300 to 500°C.
The method of claim 5,
Of the step (a)
The barium compound is any one selected from the group consisting of barium sulfate, barium nitrate, barium acetate, barium chloride, or a combination thereof. delete The method of claim 5,
The drying of the step (c) is carried out at 80 to 120° C. for 1 to 24 hours. A method for producing a deNOx catalyst having improved nitrogen oxide reduction performance at high temperature. The method of claim 5,
The method for producing a deNOx catalyst having improved nitrogen oxide reduction performance at high temperature, characterized in that the sintering of step (d) is performed for 1 to 5 hours at a temperature of 300 to 700° C. in an air atmosphere. The method of claim 5,
In step (d)
The barium is a method for producing a deNOx catalyst having improved nitrogen oxide reduction performance at high temperature, characterized in that the support is supported in an amount of 5 to 25 parts by weight based on 100 parts by weight of the support. delete delete

Images