KR102243907B1 - Ir-based catalyst improved in nox reduction performance by the carbon monoxide and hydrogen gas treatment, nox reduction apparatus and reduction method improved in performance by treatment of carbon monoxide and hydrogen gas - Google Patents

Abstract

An object of the present invention is to solve the problem that the nitrogen oxide reduction performance is deteriorated in the process of lowering after the internal temperature of the internal combustion engine rises. In addition, another object of the present invention is to prevent the need to separately regenerate the catalyst during the operation of the internal combustion engine.
The Ir-based catalyst with improved nitrogen oxide reduction performance by carbon monoxide and hydrogen gas according to the present invention is a catalyst for reducing nitrogen oxides (NOx) by using carbon monoxide (CO) in exhaust gas as a reducing agent. After firing in humid air, it is characterized in that carbon monoxide and hydrogen gas are mixed and passed through the feed gas.

Description

Ir-based catalyst with improved nitrogen oxide reduction performance by carbon monoxide and hydrogen gas treatment, nitrogen oxide reduction device and reduction method with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas {IR-BASED CATALYST IMPROVED IN NOX REDUCTION PERFORMANCE BY THE CARBON MONOXIDE AND HYDROGEN GAS TREATMENT, NOX REDUCTION APPARATUS AND REDUCTION METHOD IMPROVED IN PERFORMANCE BY TREATMENT OF CARBON MONOXIDE AND HYDROGEN GAS}

The present invention relates to an Ir-based catalyst with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas, a nitrogen oxide reduction device and a reduction method with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas, and more specifically, an internal combustion engine Ir-based catalyst with improved nitrogen oxide reduction performance by carbon monoxide and hydrogen gas treatment, which can solve the problem that the nitrogen oxide reduction performance decreases in the process of lowering after increasing the internal temperature of the unit, nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas The present invention relates to an improved nitrogen oxide reduction apparatus and a reduction method.

Fossil fuels such as coal, petroleum, natural steam, etc., and exhaust gas generated from waste combustion contain nitrogen oxides (NOx). These nitrogen oxides are pollutants that cause air pollution and must be removed before discharging them to the atmosphere. do.

Currently, selective catalytic reduction (SCR) is widely used to remove nitrogen oxides contained in exhaust gas. In the selective catalytic reduction (SCR) catalyst, ammonia or urea is injected before the catalyst for selective catalytic reduction (SCR), and nitrogen oxides in the exhaust gas are passed through the catalyst together with ammonia to change into non-polluting water and nitrogen.

The selective catalytic reduction (NH ₃ -SCR) process using ammonia as a reducing agent has been widely used due to the advantages of low ammonia emission and high NOx removal efficiency. However, there are problems such as stability problems related to the use and storage of ammonia, poisoning of the catalyst due to reaction with sulfur oxide, and the need for a large installation space. Therefore, the need for a process of performing the selective catalytic reduction method using other reducing agents without using ammonia has been continuously raised.

Moisture is present in the exhaust gas, and some of the ammonia introduced into the SCR reacts with sulfur trioxide and moisture to form ammonium sulfate. The ammonium sulfate salt is coated on the surface, crevices, pores, etc. of the catalyst to reduce the activity of the catalyst. Since the pores of the catalyst serve to increase the surface area in which nitrogen oxides and ammonia can react, catalyst performance deteriorates when the pores of the catalyst are clogged. When the catalyst surface is poisoned, the poisoned catalyst must be withdrawn from the reactor of the denitrification facility, and the catalyst must be regenerated by removing poisonous substances from the catalyst by chemical treatment, or the catalyst must be discarded.

As a way to overcome this 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.}

Republic of Korea Patent Publication No. 2019-0050345 disclosed by the present inventors uses carbon monoxide (CO) contained in exhaust gas as a reducing agent according to an Ir-based catalyst that reduces nitrogen oxides by using carbon monoxide (CO) contained in exhaust gas as a reducing agent. Thus, it can be seen that the nitrogen oxide can be reduced without introducing a separate reducing agent, and it can be seen that the problem of deteriorating the activity of the nitrogen oxide reducing catalyst at medium and high temperatures of 175°C or higher can be solved.

However, the Ir-based catalyst was found to have a problem in that the nitrogen oxide reduction performance is lowered in the process of lowering again after the temperature of the internal combustion engine rises, so the present inventors have completed the present invention to solve this problem.

Republic of Korea Patent Publication No. 10-2013-0089348 (published on August 12, 2013)

An object of the present invention is to solve the problem that the nitrogen oxide reduction performance is deteriorated in the process of lowering after the internal temperature of the internal combustion engine rises.

Another object of the present invention is to avoid the need to separately regenerate the catalyst during the operation of the internal combustion engine.

In order to achieve the above object, the present invention is a catalyst for reducing nitrogen oxides (NOx) using carbon monoxide (CO) in exhaust gas as a reducing agent, and after firing in humid air by supporting ruthenium and iridium on a support, feed gas It provides an Ir-based catalyst with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas, characterized in that carbon monoxide and hydrogen gas are mixed and passed through.

The carbon monoxide and the hydrogen gas may be mixed in a concentration ratio of 0.3 to 3 and passed through.

The iridium may be supported in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the support, and the ruthenium may be supported in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the support.

The concentration of the hydrogen gas may be 0.1 to 10%.

The sintering may be performed for 1 to 10 hours at a temperature of 300 to 800 °C in moist air.

In addition, in order to achieve the above object, the present invention includes a housing having an inlet and an outlet so that exhaust gas is introduced and discharged; An Ir-based catalyst disposed between the inlet and the outlet and reducing nitrogen oxides in the exhaust gas passing through the inlet; And a reforming device connected to one side of the housing and mixing carbon monoxide and hydrogen gas in a feed gas and spraying it to an Ir-based catalyst in the housing; and nitrogen oxide reduction performance improved by treatment of carbon monoxide and hydrogen gas. Provide a reduction device.

The Ir-based catalyst may be prepared by supporting ruthenium and iridium on a support and firing in humid air.

The carbon monoxide and the hydrogen gas may be mixed in a concentration ratio of 0.3 to 3 and passed through.

The concentration of the hydrogen gas may be 0.1 to 10%.

In addition, in order to achieve the above object, the present invention includes the steps of: (a) injecting exhaust gas into the housing; _{(b) reducing nitrogen oxides (NOx) to N 2} by injecting carbon monoxide (CO) in the housing to reduce nitrogen oxides (NOx); (c) contacting the exhaust gas with an Ir-based catalyst; And (d) mixing carbon monoxide and hydrogen gas in the feed gas and passing through the Ir-based catalyst to improve the nitrogen oxide reduction performance; including carbon monoxide and hydrogen gas treatment to improve the nitrogen oxide reduction performance. Provides.

The concentration ratio of the carbon monoxide and the hydrogen gas may be 0.3 to 3, and the passage may be performed.

The concentration of the hydrogen gas may be 0.1 to 10%.

When using the Ir-based catalyst with improved nitrogen oxide reduction performance by treatment of carbon monoxide and hydrogen gas according to the present invention, the catalyst is poisoned in the process of decreasing after increasing the internal temperature of the internal combustion engine, thereby solving the problem that the nitrogen oxide reduction performance is deteriorated. I can.

In addition, when the nitrogen oxide reduction apparatus and method for reducing nitrogen oxides with improved nitrogen oxide reduction performance by the treatment of carbon monoxide and hydrogen gas according to the present invention are used, carbon monoxide contained in exhaust gas can be used as a reducing agent, so the apparatus is simplified and economical advantages. There is this.

1 is a graph comparing the nitrogen oxide reduction performance before and after treatment of carbon monoxide and hydrogen gas in an Ir-based catalyst according to the present invention.
2 is a schematic diagram of a nitrogen oxide reduction apparatus with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas according to an embodiment of the present invention.
3 is a flowchart of a method for reducing nitrogen oxides with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas according to an embodiment of the present invention.

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.

The 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. 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.

Carbon monoxide and Hydrogen gas Nitrogen oxides by treatment Reduction performance Improved Ir system catalyst

The Ir-based catalyst with improved nitrogen oxide reduction performance by the treatment of carbon monoxide and hydrogen gas according to the present invention is a catalyst that reduces nitrogen oxides (NOx) by using carbon monoxide (CO) in exhaust gas as a reducing agent, and supports ruthenium and iridium on the support. It is characterized in that after firing in humid air, carbon monoxide and hydrogen gas are mixed and passed through the feed gas.

The Ir-based catalyst having improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas according to the present invention can be used for SCR. SCR is a technology for removing nitrogen oxides in exhaust gas generated during operation of onshore plants, ships and automobiles with selective catalytic reduction. 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. SCR 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, SCR uses ammonia (NH 3} ) or urea to provide 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 Ir-based catalyst with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas according to the present invention removes nitrogen oxides by using carbon monoxide (CO) in exhaust gas as a reducing agent. Since the exhaust gas of the internal combustion engine may include hydrocarbon, carbon monoxide, carbon dioxide, hydrogen, nitrogen, oxygen, sulfur oxide, and water in addition to nitrogen oxide, carbon monoxide in the exhaust gas can be used as a reducing agent to remove nitrogen oxide.

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 and an injection device for storing urea in the related art, so the space in the internal combustion engine can be utilized, and there is no additional cost, so there is an economic advantage. In addition, there is an advantage of reducing nitrogen oxides and removing carbon monoxide in exhaust gas at the same time.

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

The Ir-based catalyst with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas according to an embodiment of the present invention supports ruthenium and iridium on a support, and is calcined under moist air, and a mixture gas of feed gas and carbon monoxide and hydrogen gas It can be produced by passing through.

Iridium is an element with an atomic number of 77 and a transition metal with an element symbol of Ir. Iridium is hard, but has little ductility and is difficult to process because it is easily broken. The lump is silvery white, but the powder is black.

The amount of iridium supported is preferably in an appropriate range, but may be supported in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the support in order to sufficiently achieve the purpose of increasing the nitrogen oxide removal efficiency.

If iridium is supported in an amount of less than 0.1 parts by weight, the activity of the catalyst is not secured, and when it is supported in an amount exceeding 10 parts by weight, the degree of improvement in the activity of the catalyst is insignificant and economically unfavorable, so the above range is preferable.

The iridium compound useful for preparing the Ir-based catalyst according to the present invention may be any compound that is water-soluble or partially convertible to a water-soluble compound, and can be deposited on a support. For example, iridium in a metallic state, an iridium salt, an oxide, etc. are preferable, but are not limited thereto.

As the iridium salt, iridium halide is generally used. More specifically, the iridium halide may be IrI ₃ , IrBr ₃ , IrCl ₃ , IrI ₃ 4H ₂ O and IrBr ₃ 4H ₂ O, and IrCl ₃ is preferably used.

Ruthenium is an element with atomic number 44 and is a transition metal located in the center of the periodic table and is one of the platinum group metals.

The amount of ruthenium supported may be supported in an appropriate range, but in order to increase the removal efficiency of nitrogen oxides at medium and high temperatures, it is preferably supported in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the support.

0.1 part by weight of the ruthenium supported amount is the optimal amount for securing the activity of the catalyst, and the above range is preferable because the activity of the catalyst is insignificant and economically unfavorable even if the amount exceeds 10 parts by weight of the ruthenium supported amount.

The ruthenium compound useful for preparing the Ir-based catalyst according to an embodiment of the present invention may be any compound that can be easily converted into a water-soluble or partially water-soluble compound, and can be deposited on a support.

Examples of the ruthenium compound include RuCl ₃ and Ru(NO)(NO ₃ ) ₃ , but are not limited thereto, and it is preferable to use _{RuCl 3.}

The Ir-based catalyst according to an embodiment of the present invention may additionally support other noble metals in addition to ruthenium and iridium.

The noble metal component that may be additionally supported may be at least one selected from the group consisting of platinum, rhodium, palladium, and silver. Among the noble metals, platinum, rhodium, and silver are preferred.

In this case, platinum is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the support, and rhodium and silver are also preferably 0.1 to 10 parts by weight, respectively, based on 100 parts by weight of the support.

When the supported amount is less than 0.1 parts by weight, the effect of supporting additional precious metals is not exhibited, and when the amount exceeds 10 parts by weight, the properties of ruthenium and iridium, which are the main components, may be deteriorated, so the above range is preferable. In addition, the additional noble metal may additionally support two or more noble metals of platinum, rhodium, and silver with respect to iridium and ruthenium.

In the Ir-based catalyst according to an embodiment of the present invention, ruthenium may be primarily supported on a support and then iridium may be secondarily supported. In addition, it is preferable that the Ir-based catalyst according to an embodiment of the present invention simultaneously supports ruthenium and iridium in order to prevent iridium from being supported earlier than ruthenium.

This is because when iridium is first supported on the support and then ruthenium is supported, iridium and ruthenium exist separately due to the strong interaction between iridium and the support, so that a synergistic effect of iridium and ruthenium cannot be expected.

Therefore, when ruthenium is first supported on the support and then iridium is supported, a strong interaction between the support and iridium can be prevented, and iridium and ruthenium are present in close proximity to each other to improve performance.

The Ir-based catalyst according to an embodiment of the present invention may use one selected from the group consisting of aluminum oxide, zirconia, titania, silica, zeolite, ceria, and ceria-based multi-component compounds as a support. At this time, it is preferable to use aluminum oxide as a support, and the aluminum oxide may be monolithized and supported in a mixture solution of iridium and ruthenium to form a catalyst layer.

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

The aluminum oxide is generally called alumina, and is a colorless or white material that is insoluble in water. α alumina is a product of the Bayer method and has a melting point of 199 to 202 °C, and β alumina is in a stable form at high temperatures (1,500 °C). γ alumina is obtained by heating and dehydrating a hydrate or α hydrated alumina and further maintaining it at 900°C, and has a property of transitioning to α alumina when the temperature is 1,000°C or higher.

The aluminum oxide is preferred for use as a support for a catalyst because of its high specific surface area and good heat resistance against firing at elevated temperatures. It is preferable to use the aluminum oxide having a specific surface area of 5 or more, specifically 50 or more, and more specifically 100 m ^{2 /g or more.} When the specific surface area of the aluminum oxide is less than 5, there is a disadvantage that the activity of the catalyst is deteriorated, and the above range is preferable.

The Ir-based catalyst according to an embodiment of the present invention may be calcined for 1 to 10 hours at a temperature of 300 to 800 °C in moist air. The sintering may be carried out under hydrogen, argon, and positive air pressure, but it is preferably carried out under humid air. When firing is performed in a hydrogen atmosphere, the catalyst structure is different, and it is not easy to remove the constituents of the mixture of iridium and ruthenium, so it is preferable to perform the firing in humid air.

By passing a feed gas, a mixed gas of carbon monoxide and hydrogen gas through the Ir-based catalyst, it is possible to improve the nitrogen oxide reduction performance.

According to an embodiment of the present invention, the concentration ratio of the carbon monoxide and the hydrogen gas may be mixed at 0.3 to 3 and passed.

If the concentration ratio of carbon monoxide and hydrogen gas is less than 0.3, excessive energy is consumed for hydrogen production, which is uneconomical.If the concentration ratio exceeds 3, fuel consumption for carbon monoxide production is excessive, and carbon monoxide slip phenomenon occurs due to excessive use of carbon monoxide. Because it can be, the above range is preferable.

According to an embodiment of the present invention, the concentration of the hydrogen gas may be 0.1 to 10%. If the concentration of the hydrogen gas is less than 0.1%, it is difficult to expect the improvement of the nitrogen oxide reduction performance due to catalyst regeneration, and if it exceeds 10%, excessive energy is consumed for hydrogen production, which is uneconomical, so the above range is preferable.

At this time, the carbon monoxide and hydrogen gas passing through may be injected from the outside or may be injected by reforming the fuel from the outside, but it is preferable that the fuel is reformed and injected.

On the other hand, when reforming the fuel and injecting carbon monoxide and hydrogen gas, a reforming device may be used. In the case of injecting carbon monoxide and hydrogen gas using the reforming device, fuel and air are introduced and power is supplied to combust a mixture gas of fuel and air, and a reforming reaction is performed to produce a synthetic gas containing carbon monoxide and hydrogen gas as the main components. Thus, it can be passed through the Ir-based catalyst.

1 is a graph comparing the nitrogen oxide reduction performance before and after treatment of carbon monoxide and hydrogen gas in an Ir-based catalyst according to the present invention.

Referring to FIG. 1, the conventional Ir-based catalyst has a nitrogen oxide conversion rate of 100% at a temperature of 200° C., but there is a problem that the conversion rate drops to 6% in the process of lowering to 200° C. after the temperature is raised to 300° C.

However, according to an embodiment of the present invention, when the feed gas, the mixed gas of carbon monoxide and hydrogen gas is passed through the Ir-based catalyst, a problem in which the nitrogen oxide conversion rate is lowered can be solved. Referring to FIG. 1, carbon monoxide and 0.23% hydrogen gas were supplied together with feed gas at a temperature of 200° C. so that the concentration ratio of carbon monoxide and hydrogen gas was 3. After 5 minutes elapsed, it was confirmed that the nitrogen oxide conversion rate recovered from 6% to 20%, and after 10 minutes elapsed, the nitrogen oxide conversion rate recovered to 89%.

Through this, if the Ir catalyst with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas according to the present invention is used, the catalyst is poisoned in the process of lowering after increasing the internal temperature of the internal combustion engine, thereby solving the problem that the nitrogen oxide reduction performance is deteriorated. It was confirmed that it can be.

In addition, according to the present invention, since carbon monoxide and hydrogen gas are introduced as a catalyst by reforming the fuel from the outside, there is no need to separately regenerate the catalyst to recover the deterioration of the catalyst during operation of the internal combustion engine, making the overall nitrogen oxide reduction process very simple. There is this.

Carbon monoxide and Hydrogen gas Nitrogen oxides by treatment Reduction performance Improved nitrogen oxide reduction device

2 is a schematic diagram of a reduction apparatus with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas according to an embodiment of the present invention.

Referring to FIG. 2, the present invention provides a reduction device having improved nitrogen oxide reduction performance by treating carbon monoxide and hydrogen gas including a housing 10, an Ir-based catalyst 30, and a reforming device 50. . The housing 10 is provided with an inlet and an outlet so that exhaust gas is introduced and discharged, and the Ir-based catalyst 30 is disposed between the inlet and the outlet, and reduces nitrogen oxides in the exhaust gas that has passed through the inlet. . The reforming device 50 is connected to one side of the housing 10 and mixes carbon monoxide and hydrogen gas in the feed gas and injects it to the Ir-based catalyst 30 inside the housing 10.

Exhaust gas generated by combustion of the engine is introduced into the inlet of the housing 10.

The exhaust gas is generated by engine combustion of an internal combustion engine. The internal combustion engine may be an automobile, a ship, an industrial machine, a power plant, an incinerator, or a boiler.

The exhaust gas may include nitrogen oxides, hydrocarbons, carbon monoxide, carbon dioxide, hydrogen, nitrogen, oxygen, sulfur oxides, particulate matter, and water.

Nitrogen oxide in the exhaust gas introduced through the inlet is reduced to nitrogen (N ₂ ), carbon dioxide (CO ₂ ), and water (H ₂ O) through a reduction process inside the housing 10. At this time, the reduced nitrogen and carbon dioxide are discharged through the outlet of the housing 10.

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 Ir-based catalyst 30 is disposed between the inlet and the outlet of the housing 10, and reduces nitrogen oxides in the exhaust gas that has passed through the inlet.

The Ir-based catalyst 30 may be used for SCR. SCR is a technology for removing nitrogen oxides in exhaust gas generated during operation of onshore plants, ships and automobiles with selective catalytic reduction. 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. SCR 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.

However, the Ir-based catalyst 30 according to the present invention uses carbon monoxide (CO) in exhaust gas as a reducing agent to remove nitrogen oxides. Since the exhaust gas of the internal combustion engine may include hydrocarbon, carbon monoxide, carbon dioxide, hydrogen, nitrogen, oxygen, sulfur oxide, and water in addition to nitrogen oxide, carbon monoxide in the exhaust gas can be used as a reducing agent to remove nitrogen oxide.

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 the space in the internal combustion engine can be utilized, and there is no additional cost, so there is an economic advantage. In addition, there is an advantage of reducing nitrogen oxides and removing carbon monoxide in exhaust gas at the same time.

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 concentration of nitrogen oxides in the exhaust gas that can be treated by the present invention is not limited.

The Ir-based catalyst 30 may be prepared by supporting ruthenium and iridium on a support and firing in humid air.

The amount of iridium supported is preferably in an appropriate range, but may be supported in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the support in order to sufficiently achieve the purpose of increasing the nitrogen oxide removal efficiency. If iridium is supported in an amount of less than 0.1 parts by weight, the activity of the catalyst is not secured, and when it is supported in an amount exceeding 10 parts by weight, the degree of improvement in the activity of the catalyst is insignificant and economically unfavorable, so the above range is preferable.

The iridium compound useful for preparing the Ir-based catalyst 30 according to an embodiment of the present invention may be any compound that can be easily converted into a water-soluble or partially water-soluble compound, and can be deposited on a support. For example, iridium in a metallic state, an iridium salt, an oxide, etc. are preferable, but are not limited thereto.

As the iridium salt, iridium halide is generally used. More specifically, the iridium halide may be IrI ₃ , IrBr ₃ , IrCl ₃ , IrI ₃ ·4H ₂ O and IrBr ₃ ·4H ₂ O, and it is preferable to use _{IrCl 3.}

The amount of ruthenium supported may be supported in an appropriate range, but it is preferably supported in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the support in order to increase the efficiency of removing nitrogen oxides at medium and high temperatures. 0.1 part by weight of the ruthenium supported amount is an optimal amount for securing the activity of the catalyst, and even if the amount exceeded 10 parts by weight, the activity of the catalyst is insignificant and economically unfavorable, so the above range is preferable.

The ruthenium compound useful for preparing the Ir-based catalyst 30 according to an embodiment of the present invention may be any compound that can be easily converted into a water-soluble or partially water-soluble compound, and can be deposited on a support.

Examples of the ruthenium compound include RuCl ₃ and Ru(NO)(NO ₃ ) ₃ , but are not limited thereto, and it is preferable to use _{RuCl 3.}

The Ir-based catalyst 30 according to an embodiment of the present invention may additionally support other noble metals in addition to ruthenium and iridium.

The noble metal component that may be additionally supported may be at least one selected from the group consisting of platinum, rhodium, palladium, and silver. Among the noble metals, platinum, rhodium, and silver are preferred.

In this case, platinum is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the support, and rhodium and silver are also preferably 0.1 to 10 parts by weight, respectively, based on 100 parts by weight of the support.

If the supported amount is less than 0.1 parts by weight, the effect of supporting additional precious metals is not exhibited, and when the amount exceeds 10 parts by weight, the properties of ruthenium and iridium, which are the main components, may be deteriorated, so the above range is preferable. In addition, the additional noble metal may additionally support two or more noble metals of platinum, rhodium, and silver with respect to iridium and ruthenium.

In the Ir-based catalyst 30 according to an embodiment of the present invention, ruthenium may be primarily supported on a support and then iridium may be secondaryly supported. In addition, it is preferable that the Ir-based catalyst 30 according to an embodiment of the present invention simultaneously support ruthenium and iridium in order to prevent iridium from being supported earlier than ruthenium.

This is because when iridium is first supported on the support and then ruthenium is supported, iridium and ruthenium exist separately due to the strong interaction between iridium and the support, so that a synergistic effect of iridium and ruthenium cannot be expected.

Therefore, when ruthenium is first supported on the support and then iridium is supported, a strong interaction between the support and iridium can be prevented, and iridium and ruthenium are present in close proximity to each other to improve performance.

The Ir-based catalyst 30 according to an embodiment of the present invention may use one selected from the group consisting of aluminum oxide, zirconia, titania, silica, zeolite, ceria, and ceria-based multi-component compounds as a support. At this time, it is preferable to use aluminum oxide as a support, and the aluminum oxide may be monolithized and supported in a mixture solution of iridium and ruthenium to form a catalyst layer.

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

The aluminum oxide is generally called alumina, and is a colorless or white material that is insoluble in water. α alumina is a product of the Bayer method and has a melting point of 199 to 202 °C, and β alumina is in a stable form at high temperatures (1,500 °C). γ alumina is obtained by dehydrating a hydrate or α hydrated alumina by heating and maintaining it at 900°C, and has a property of transitioning to α alumina when the temperature is 1,000°C or higher.

The aluminum oxide is preferred for use as a support for a catalyst because of its high specific surface area and good heat resistance against firing at elevated temperatures.

It is preferable to use the aluminum oxide having a specific surface area of 5 or more, specifically 50 or more, and more specifically 100 m ^{2 /g or more.} When the specific surface area of the aluminum oxide is less than 5, there is a disadvantage that the activity of the catalyst is deteriorated, and the above range is preferable.

The Ir-based catalyst 30 according to an embodiment of the present invention may be calcined for 1 to 10 hours at a temperature of 300 to 800 °C in moist air.

The sintering may be carried out under hydrogen, argon, and positive air pressure, but it is preferably carried out under humid air.

When firing is performed in a hydrogen atmosphere, the catalyst structure is different, and it is not easy to remove the constituents of the mixture of iridium and ruthenium, so it is preferable to perform the firing in humid air.

By passing through the Ir-based catalyst 30 by mixing carbon monoxide and hydrogen gas in the feed gas, it is possible to improve the nitrogen oxide reduction performance.

According to an embodiment of the present invention, the concentration ratio of the carbon monoxide and the hydrogen gas may be mixed at 0.3 to 3 and passed.

If the concentration ratio of carbon monoxide and hydrogen gas is less than 0.3, excessive energy is consumed for hydrogen production, which is uneconomical.If the concentration ratio exceeds 3, fuel consumption for carbon monoxide production is excessive, and carbon monoxide slip phenomenon occurs due to excessive use of carbon monoxide. Because it can be, the above range is preferable.

According to an embodiment of the present invention, the concentration of the hydrogen gas may be 0.1 to 10%. If the concentration of the hydrogen gas is less than 0.1%, it is difficult to expect improvement of the nitrogen oxide reduction performance due to catalyst regeneration, and if it exceeds 10%, the above range is preferable because excessive energy is consumed for hydrogen production and is uneconomical.

According to an embodiment of the present invention, the carbon monoxide and hydrogen gas may be mixed and passed for 0.1 to 10 minutes.

If the mixed gas of carbon monoxide and hydrogen gas is passed in less than 0.1 minutes, the catalyst regeneration effect is insignificant, and the improvement of nitrogen oxide reduction performance cannot be expected.If it passes more than 10 minutes, it is uneconomical due to excessive use of carbon monoxide and hydrogen gas. .

At this time, the carbon monoxide and hydrogen gas passing through may be injected from the outside or may be injected by reforming the fuel from the outside, but it is preferable that the fuel is reformed and injected.

On the other hand, when reforming the fuel and injecting carbon monoxide and hydrogen gas, the reforming device 50 may be used. In the case of injecting carbon monoxide and hydrogen gas using the reforming device 50, fuel and air are introduced and power is supplied to combust a mixture gas of fuel and air, and a reforming reaction is performed to synthesize carbon monoxide and hydrogen gas as main components. Gas can be produced and passed through the Ir-based catalyst 30.

The reforming device 50 is connected to one side of the housing 10 and injects carbon monoxide and hydrogen gas generated through a reforming reaction by introducing exhaust gas to the Ir-based catalyst 30 in the housing 10 do.

The reforming device 50 may be a device capable of receiving a general fuel (LPG, LNG, methane, coal gas, methanol, etc.) containing carbon monoxide and hydrogen gas chemically and converting it into carbon monoxide and hydrogen gas.

1 is a graph comparing the nitrogen oxide reduction performance before and after treatment of carbon monoxide and hydrogen gas in an Ir-based catalyst according to the present invention.

Referring to FIG. 1, the conventional Ir-based catalyst has a nitrogen oxide conversion rate of 100% at a temperature of 200° C., but there is a problem that the conversion rate drops to 6% in the process of lowering to 200° C. after the temperature is raised to 300° C.

However, according to an embodiment of the present invention, when the feed gas, the mixed gas of carbon monoxide and hydrogen gas is passed through the Ir-based catalyst, a problem in which the nitrogen oxide conversion rate is lowered can be solved. Referring to FIG. 1, carbon monoxide and 0.23% hydrogen gas were supplied together with feed gas at a temperature of 200° C. so that the concentration ratio of carbon monoxide and hydrogen gas was 3. After 5 minutes elapsed, it was confirmed that the nitrogen oxide conversion rate recovered from 6% to 20%, and after 10 minutes elapsed, the nitrogen oxide conversion rate recovered to 89%.

Through this, if the Ir catalyst with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas according to the present invention is used, the catalyst is poisoned in the process of lowering after increasing the internal temperature of the internal combustion engine, thereby solving the problem that the nitrogen oxide reduction performance is deteriorated. It was confirmed that it can be.

In addition, according to the present invention, since carbon monoxide and hydrogen gas are introduced as a catalyst by reforming the fuel from the outside, there is no need to separately regenerate the catalyst to recover the deterioration of the catalyst during operation of the internal combustion engine, making the overall nitrogen oxide reduction process very simple. There is this.

Carbon monoxide and Hydrogen gas Nitrogen oxides by treatment Reduction performance Improved nitrogen oxides Reduction method

3 is a flowchart of a method for reducing nitrogen oxides with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas according to an embodiment of the present invention.

Referring to FIG. 3, a method for reducing nitrogen oxides with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas according to the present invention includes the steps of: (a) injecting exhaust gas into a housing; _{(b) reducing nitrogen oxides (NOx) to N 2} by injecting carbon monoxide (CO) in the housing to reduce nitrogen oxides (NOx); (c) contacting the exhaust gas with an Ir-based catalyst; And (d) mixing carbon monoxide and hydrogen gas in the feed gas and passing through the Ir-based catalyst to improve nitrogen oxide reduction performance.

First, exhaust gas is injected into the housing (S10).

The housing may have an inlet and an outlet so that exhaust gas is introduced and discharged. Exhaust gas generated by combustion of the engine is introduced through the inlet of the housing, and nitrogen oxide contained in the exhaust gas is reduced to _{N 2 and discharged through the outlet of the housing.}

The exhaust gas is generated by engine combustion of an internal combustion engine. The internal combustion engine may be an automobile, a ship, an industrial machine, a power plant, an incinerator, or a boiler.

The exhaust gas may include nitrogen oxide, hydrocarbon, carbon dioxide, carbon monoxide, hydrogen, nitrogen, oxygen, sulfur oxide, particulate matter, and water.

Nitrogen oxides in the exhaust gas introduced through the inlet are reduced inside the housing and are reduced to nitrogen (N ₂ ), carbon dioxide (CO ₂ ), and water (H ₂ O). At this time, the reduced nitrogen and carbon dioxide are discharged through the outlet of the housing.

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 of the exhaust gas that can be treated by the present invention is not limited.

Next, carbon monoxide (CO) is injected into the housing to reduce nitrogen oxides (NOx) contained in the exhaust gas to reduce nitrogen oxides (NOx) to N ₂ (S20).

In the reduction method with improved nitrogen oxide reduction performance by treatment of carbon monoxide and hydrogen gas according to an embodiment of the present invention, carbon monoxide may be injected from the outside for reduction of nitrogen oxide or carbon monoxide contained in exhaust gas may be used, but exhaust gas It is preferable to use carbon monoxide contained in it as a reducing agent.

The exhaust gas of the internal combustion engine may include hydrocarbons, carbon monoxide, carbon dioxide, hydrogen, nitrogen, oxygen, sulfur oxides, and water in addition to nitrogen oxides. Therefore, 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 internal 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.

Next, the exhaust gas is brought into contact with the Ir-based catalyst (S30).

The Ir-based catalyst may be prepared by supporting ruthenium and iridium on a support and firing in humid air.

The amount of iridium supported is preferably in an appropriate range, but may be supported in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the support in order to sufficiently achieve the purpose of increasing the nitrogen oxide removal efficiency. If iridium is supported in an amount of less than 0.1 parts by weight, the activity of the catalyst is not secured, and when it is supported in an amount exceeding 10 parts by weight, the degree of improvement in the activity of the catalyst is insignificant and economically unfavorable, so the above range is preferable.

As the iridium salt, iridium halide is generally used. More specifically, the iridium halide may be IrI ₃ , IrBr ₃ , IrCl ₃ , IrI ₃ ·4H ₂ O and IrBr ₃ ·4H ₂ O, and it is preferable to use _{IrCl 3.}

The amount of ruthenium supported may be supported in an appropriate range, but it is preferably supported in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the support in order to increase the efficiency of removing nitrogen oxides at medium and high temperatures. 0.1 part by weight of the ruthenium supported amount is an optimal amount for securing the activity of the catalyst, and even if the amount exceeded 10 parts by weight, the activity of the catalyst is insignificant and economically unfavorable, so the above range is preferable.

The ruthenium compound useful for preparing the Ir-based catalyst according to an embodiment of the present invention may be any compound that can be easily converted into a water-soluble or partially water-soluble compound, and can be deposited on a support.

Examples of the ruthenium compound include RuCl ₃ and Ru(NO)(NO ₃ ) ₃ , but are not limited thereto, and it is preferable to use _{RuCl 3.}

The Ir-based catalyst according to an embodiment of the present invention may additionally support other noble metals in addition to ruthenium and iridium.

The noble metal component that may be additionally supported may be at least one selected from the group consisting of platinum, rhodium, palladium, and silver. Among the noble metals, platinum, rhodium, and silver are preferred.

In this case, platinum is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the support, and rhodium and silver are also preferably 0.1 to 10 parts by weight, respectively, based on 100 parts by weight of the support.

If the supported amount is less than 0.1 parts by weight, the effect of supporting additional precious metals is not exhibited, and when the amount exceeds 10 parts by weight, the properties of ruthenium and iridium, which are the main components, may be deteriorated, so the above range is preferable. In addition, the additional noble metal may additionally support two or more noble metals of platinum, rhodium, and silver with respect to iridium and ruthenium.

In the Ir-based catalyst according to an embodiment of the present invention, ruthenium may be primarily supported on a support and then iridium may be secondarily supported. In addition, it is preferable that the Ir-based catalyst according to an embodiment of the present invention simultaneously supports ruthenium and iridium in order to prevent iridium from being supported earlier than ruthenium.

This is because when iridium is first supported on the support and then ruthenium is supported, iridium and ruthenium exist separately due to the strong interaction between iridium and the support, so that a synergistic effect of iridium and ruthenium cannot be expected.

Therefore, when ruthenium is first supported on the support and then iridium is supported, a strong interaction between the support and iridium can be prevented, and iridium and ruthenium are present in close proximity to each other to improve performance.

The Ir-based catalyst according to an embodiment of the present invention may use one selected from the group consisting of aluminum oxide, zirconia, titania, silica, zeolite, ceria, and ceria-based multi-component compounds as a support. At this time, it is preferable to use aluminum oxide as a support, and the aluminum oxide may be monolithized and supported in a mixture solution of iridium and ruthenium to form a catalyst layer.

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

The aluminum oxide is generally called alumina, and is a colorless or white material that is insoluble in water. α alumina is a product of the Bayer method and has a melting point of 199 to 202 °C, and β alumina is in a stable form at high temperatures (1,500 °C). γ alumina is obtained by dehydrating a hydrate or α hydrated alumina by heating and maintaining it at 900°C, and has a property of transitioning to α alumina when the temperature is 1,000°C or higher.

The aluminum oxide is preferred for use as a support for a catalyst because of its high specific surface area and good heat resistance against firing at elevated temperatures.

It is preferable to use the aluminum oxide having a specific surface area of 5 or more, specifically 50 or more, and more specifically 100 m ^{2 /g or more.} When the specific surface area of the aluminum oxide is less than 5, there is a disadvantage that the activity of the catalyst is deteriorated, and the above range is preferable.

The Ir-based catalyst according to an embodiment of the present invention may be calcined for 1 to 10 hours at a temperature of 300 to 800 °C in moist air.

The sintering may be carried out under hydrogen, argon, and positive air pressure, but it is preferably carried out under humid air.

When firing is performed in a hydrogen atmosphere, the catalyst structure is different, and it is not easy to remove the constituents of the mixture of iridium and ruthenium, so it is preferable to perform the firing in humid air.

Finally, carbon monoxide and hydrogen gas are mixed in the feed gas and passed through the Ir-based catalyst to improve the nitrogen oxide reduction performance (S40).

According to an embodiment of the present invention, the concentration ratio of the carbon monoxide and the hydrogen gas may be mixed at 0.3 to 3 and passed.

If the concentration ratio of carbon monoxide and hydrogen gas is less than 0.3, excessive energy is consumed for hydrogen production, which is uneconomical.If the concentration ratio exceeds 3, fuel consumption for carbon monoxide production is excessive, and carbon monoxide slip phenomenon occurs due to excessive use of carbon monoxide. Because it can be, the above range is preferable.

According to an embodiment of the present invention, the concentration of the hydrogen gas may be 0.1 to 10%. If the concentration of the hydrogen gas is less than 0.1%, it is difficult to expect improvement of the nitrogen oxide reduction performance due to catalyst regeneration, and if it exceeds 10%, the above range is preferable because excessive energy is consumed for hydrogen production and thus it is uneconomical.

According to an embodiment of the present invention, the carbon monoxide and hydrogen gas may be mixed and passed for 0.1 to 10 minutes.

If the mixed gas of carbon monoxide and hydrogen gas is passed in less than 0.1 minutes, the catalyst regeneration effect is insignificant, and the improvement of nitrogen oxide reduction performance cannot be expected.If it passes more than 10 minutes, it is uneconomical due to excessive use of carbon monoxide and hydrogen gas. .

At this time, the carbon monoxide and hydrogen gas passing through may be injected from the outside or may be injected by reforming the fuel from the outside, but it is preferable that the fuel is reformed and injected.

On the other hand, when reforming the fuel and injecting carbon monoxide and hydrogen gas, a reforming device may be used. In the case of injecting carbon monoxide and hydrogen gas using the reforming device, fuel and air are introduced and power is supplied to combust a mixture gas of fuel and air, and a reforming reaction is performed to produce a synthetic gas containing carbon monoxide and hydrogen gas as the main components. Thus, it can be passed through the Ir-based catalyst.

In the reforming device, the reforming device is connected to one side of the housing and injects carbon monoxide and hydrogen gas generated through a reforming reaction by introducing exhaust gas to the Ir-based catalyst in the housing.

The reforming device is sufficient as long as it is a device capable of converting into carbon monoxide and hydrogen gas by receiving a general fuel (LPG, LNG, methane, coal gas, methanol, etc.) containing chemically carbon monoxide and hydrogen gas.

1 is a graph comparing the nitrogen oxide reduction performance before and after treatment of carbon monoxide and hydrogen gas in an Ir-based catalyst according to the present invention.

Referring to FIG. 1, the conventional Ir-based catalyst has a nitrogen oxide conversion rate of 100% at a temperature of 200° C., but there is a problem that the conversion rate drops to 6% in the process of lowering to 200° C. after the temperature is raised to 300° C.

However, according to an embodiment of the present invention, when the feed gas, the mixed gas of carbon monoxide and hydrogen gas is passed through the Ir-based catalyst, a problem in which the nitrogen oxide conversion rate is lowered can be solved. Referring to FIG. 1, carbon monoxide and 0.23% hydrogen gas were supplied together with feed gas at a temperature of 200° C. so that the concentration ratio of carbon monoxide and hydrogen gas was 3. After 5 minutes elapsed, it was confirmed that the nitrogen oxide conversion rate recovered from 6% to 20%, and after 10 minutes elapsed, the nitrogen oxide conversion rate recovered to 89%.

Through this, if the Ir catalyst with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas according to the present invention is used, the catalyst is poisoned in the process of lowering after increasing the internal temperature of the internal combustion engine, thereby solving the problem that the nitrogen oxide reduction performance is deteriorated. It was confirmed that it can be.

In addition, according to the present invention, since carbon monoxide and hydrogen gas are introduced as a catalyst by reforming the fuel from the outside, there is no need to separately regenerate the catalyst to recover the deterioration of the catalyst during operation of the internal combustion engine, making the overall nitrogen oxide reduction process very simple. There is this.

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 One: Ir system catalyst( IrRu / Al ₂ O ₃ ) Of the manufacture

First, 0.190 g of _{IrCl 3 sample and 0.193 g of RuCl 3} sample were simultaneously dissolved in water, and then immersed in 5 g of γ-aluminum oxide, and then dried at 100° C. for 12 hours. After drying, the sample was calcined for 4 hours at a temperature of 500° C. in humid air, and an IrRu/Al ₂ O ₃ catalyst in which iridium-ruthenium was supported on aluminum oxide was prepared.

Experimental example 1: Confirmation of nitrogen oxide removal performance

For the nitrogen oxide removal performance of the Ir-based catalyst prepared in Example 1 above, a feed gas of nitrogen oxide (NO) 50 ppm, carbon monoxide (CO) 0.7%, oxygen (O ₂ ) 5%, and N ₂ balanced was supplied and 200 It was measured under the conditions of °C and GHSV 200,000 h ^-1.

1 is a graph comparing the nitrogen oxide reduction performance before and after treatment of carbon monoxide and hydrogen gas in an Ir-based catalyst according to the present invention.

Referring to FIG. 1, the conventional Ir-based catalyst has a nitrogen oxide conversion rate of 100% at a temperature of 200° C., but there is a problem that the conversion rate drops to 6% in the process of lowering to 200° C. after the temperature is raised to 300° C.

However, according to an embodiment of the present invention, when the feed gas, the mixed gas of carbon monoxide and hydrogen gas is passed through the Ir-based catalyst, a problem in which the nitrogen oxide conversion rate is lowered can be solved. Referring to FIG. 1, carbon monoxide and 0.23% hydrogen gas were supplied together with feed gas at a temperature of 200° C. so that the concentration ratio of carbon monoxide and hydrogen gas was 3. After 5 minutes elapsed, it was confirmed that the nitrogen oxide conversion rate recovered from 6% to 20%, and after 10 minutes elapsed, the nitrogen oxide conversion rate recovered to 89%.

Through this, if the Ir catalyst with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas according to the present invention is used, the catalyst is poisoned in the process of lowering after increasing the internal temperature of the internal combustion engine, thereby solving the problem that the nitrogen oxide reduction performance is deteriorated. It was confirmed that it can be.

In addition, according to the present invention, since carbon monoxide and hydrogen gas are introduced as a catalyst by reforming the fuel from the outside, there is no need to separately regenerate the catalyst to recover the deterioration of the catalyst during operation of the internal combustion engine, making the overall nitrogen oxide reduction process very simple. There is this.

So far, specific details of an Ir-based catalyst with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas according to an embodiment of the present invention, a nitrogen oxide reduction apparatus and reduction method with improved nitrogen oxide reduction performance by treatment with carbon monoxide and hydrogen gas Although the embodiments have been described, it is obvious that various embodiments can be modified without departing from the scope of the present invention.

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.

10: housing
30: Ir-based catalyst
50: reformer

Claims (12)

As an Ir-based catalyst that reduces nitrogen oxides (NOx) using carbon monoxide (CO) in exhaust gas as a reducing agent,
It is prepared by supporting ruthenium and iridium on a support and firing in humid air,
By mixing carbon monoxide and hydrogen gas in the exhaust gas and passing it through the poisoned Ir-based catalyst, it restores the nitrogen oxide reduction performance,
The concentration of the hydrogen gas is 0.2 to 10% by volume, the concentration of carbon monoxide is three times the concentration of the hydrogen gas (by volume),
Characterized in that the mixture gas of exhaust gas, carbon monoxide and hydrogen gas is passed through the poisoned Ir-based catalyst for 5 to 10 minutes,
Ir-based catalyst. delete The method of claim 1,
The iridium is supported at 0.1 to 10 parts by weight based on 100 parts by weight of the support, and the ruthenium is supported at 0.1 to 10 parts by weight based on 100 parts by weight of the support,
Ir-based catalyst. delete The method of claim 1,
The sintering is characterized in that it is carried out for 1 to 10 hours at a temperature of 300 to 800 °C in moist air,
Ir-based catalyst. A housing having an inlet and an outlet so that exhaust gas is introduced and discharged;
An Ir-based catalyst disposed between the inlet and the outlet and reducing nitrogen oxides using carbon monoxide (CO) in the exhaust gas passing through the inlet as a reducing agent; And
A reforming device connected to one side of the housing and mixing carbon monoxide and hydrogen gas in exhaust gas and injecting the poisoned Ir-based catalyst; Including,
The Ir-based catalyst is prepared by supporting ruthenium and iridium on a support and firing in humid air,
The nitrogen oxide reduction performance is restored by passing the mixed gas of exhaust gas, carbon monoxide and hydrogen gas injected from the reforming device through the poisoned Ir-based catalyst,
The concentration of the hydrogen gas is 0.2 to 10% by volume, the concentration of carbon monoxide is three times the concentration of the hydrogen gas (by volume),
Characterized in that the mixture gas of exhaust gas, carbon monoxide and hydrogen gas is passed through the poisoned Ir-based catalyst for 5 to 10 minutes,
Nitrogen oxide reduction device. delete delete delete (a) injecting exhaust gas into the housing;
(b) contacting the exhaust gas with an Ir-based catalyst;
_{(c) reducing nitrogen oxides (NOx) to N 2} using carbon monoxide (CO) in the exhaust gas as a reducing agent; And
(d) recovering nitrogen oxide reduction performance by passing a mixed gas of exhaust gas, carbon monoxide, and hydrogen gas through the poisoned Ir-based catalyst; Including,
Steps (a) to (c) proceed sequentially, and step (d) proceeds when the Ir-based catalyst is poisoned,
The Ir-based catalyst is prepared by supporting ruthenium and iridium on a support and firing in humid air,
The concentration of the hydrogen gas is 0.2 to 10% by volume, the concentration of carbon monoxide is three times the concentration of the hydrogen gas (by volume),
Characterized in that the mixture gas of exhaust gas, carbon monoxide and hydrogen gas is passed through the poisoned Ir-based catalyst for 5 to 10 minutes,
How to reduce nitrogen oxides. delete delete

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