KR20030004660A - Cleaning method of exhaust gas containing ammonia/hydrogen mixtures and the apparatus therefor - Google Patents

Abstract

The present invention relates to a flue gas purification method containing ammonia / hydrogen mixed gas and an apparatus thereof. Specifically, the present invention removes particulate matter from the exhaust gas discharged from the semiconductor manufacturing process using a porous filter and converts the ammonia / hydrogen mixed gas into nitrogen and water using a reactor filled with a catalyst for ammonia decomposition and a catalyst for residual gas treatment. It provides a method and apparatus for purification. The exhaust gas purification method of the present invention can effectively remove high flow rate and high concentration ammonia / hydrogen mixed gas contained in exhaust gas, and thus can be effectively used to treat environmental pollutants in semiconductor and other chemical processes.

Description

Cleaning method of exhaust gas containing ammonia / hydrogen mixtures and the apparatus therefor}

The present invention relates to a method for purifying particulate matter and ammonia / hydrogen mixed gas contained in flue gas, and more particularly, to a particulate filter and ammonia / hydrogen mixed gas contained in flue gas discharged from a semiconductor manufacturing process. A method and apparatus for purifying with a catalyst are provided.

The semiconductor manufacturing process is composed of a continuous chemical process such as a wafer cleaning process, an oxidation process, a diffusion process, a photosensitive and forming process, an etching process, and a deposition process. During this process, toxic and corrosive gases such as Cl ₂ , HCl, BCl ₃ , F ₂ , HF, BF ₃ , HBr, PFCs (Perfluorinated Compounds), SiH ₄ , Si ₂ H ₆ , SiH ₂ Cl ₂ , NH ₃ , PH ₃ or AsH ₃ and the like are used, some of these toxic gases are consumed in the process and the remaining unreacted toxic gases are released to the outside.

In the semiconductor manufacturing process, particularly in the nitride film process, a high flow rate and a high concentration of ammonia / hydrogen mixed gas are used. Ammonia is a colorless, toxic, flammable gas that is known to have a great effect on humans and ecosystems. Therefore, it is mandatory to remove the limit to 25 ppm or less (OSHA, Occupational Safety & Health Administration) before discharge to the atmosphere. Hydrogen has a wide range of ignition (lower limit of ignition: 4%, redemption value: 75%), which may cause fire and explosion in industrial plants. Therefore, hydrogen gas may be lowered to the lower limit of explosion (4%) before being discharged to the atmosphere. Must be removed (OSHA, Occupational Safety & Health Administration).

Combustion method, wet scrubbing method and adsorption method are used for the purification of flue gas containing ammonia and hydrogen. The combustion method is a method of injecting air into a flue gas containing ammonia / hydrogen mixed gas and removing it by high temperature combustion. Since the combustion method performs combustion reaction at high temperature above 850 ℃, it is necessary to use expensive materials with high alkali resistance, and the auxiliary flame is required to prevent the flame from extinguishing due to the low flame transfer rate of ammonia gas. The device is complicated and a large amount of nitrogen oxides (NOx), which are secondary air pollutants, are generated. US Patent 3,467,491 and 4,179,407 propose a method for converting nitrogen and water by oxidizing and decomposing ammonia with a metal catalyst in a reaction condition of 300 ° C. or less in order to solve the disadvantage that a large amount of nitrogen oxides are generated during high temperature combustion of ammonia. However, this method has a problem that it is difficult to control nitrogen oxide (NOx) generated by oxidation of ammonia as well as the removal efficiency of ammonia when high flow rate, high concentration of ammonia / hydrogen mixed gas is introduced.

The wet scrubbing method removes ammonia by spraying water on it using the solubility of water in the ammonia gas. The wet method has a disadvantage in that the removal efficiency of ammonia gas is as low as 60-75% and a large amount of industrial water is required. In addition, a large amount of neutralizing agent (sulfuric acid, etc.) is required to neutralize strong alkaline wastewater such as ammonia water, and a wastewater treatment plant is required for the final treatment of the neutralized wastewater, and the annual maintenance cost is high. There is a need for a post-treatment device to remove this since it will be vaporized and released into the atmosphere by an amount corresponding to its vapor pressure. Furthermore, in the case of treating the ammonia / hydrogen mixed gas by the wet method, since the solubility of hydrogen in water is very low, the hydrogen gas is not removed. In order to solve this problem, a method of removing hydrogen by introducing a combustion method at the rear end of the wet method has been attempted. However, in this case, there is a problem in that unreacted ammonia generated at the rear end of the wet removal device is converted to nitrogen oxide to generate secondary air pollutants.

The adsorption method is a method of adsorbing and removing ammonia using an adsorbent. The adsorption method has been widely used in recent years because it has a high ammonia removal efficiency and does not discharge secondary pollutants (US Patent No. 5,320,817; US Patent No. 5,597,540; US Patent No. 5,632,964). However, this method is limited in the adsorption capacity (Liter _-ammonia / Liter _-adsorbent ) to the ammonia gas of the _adsorbent , it is difficult to frequently exchange the adsorbent according to the flow rate and concentration of the incoming ammonia. In other words, when a high flow rate and a high concentration of ammonia / hydrogen mixed gas are introduced into the adsorbent, the exchange cycle of the adsorbent is shortened, resulting in low operation efficiency and increased cost. For example, if 20 L / min of high flow rate ammonia enters the adsorbent bed with ammonia treatment capacity of 100 L _-ammonia / L _-adsorbent and 200 L charge, the average lifetime of the adsorbent is very short, about 1.8 days. In addition, when high flow rate and high concentration of ammonia is introduced, the adsorption performance is deteriorated due to the adsorption heat generated. Therefore, it is mainly limited to low flow rate and low concentration of ammonia flue gas treatment. This method also has the disadvantage that the adsorbent does not remove hydrogen.

In order to solve the above problem, a method of decomposing high flow rate and high concentration of ammonia into hydrogen and nitrogen using a catalyst and then removing unreacted residual ammonia using an adsorbent has been proposed (US Pat. No. 5,632,964). However, the method is limited to the treatment of ammonia at a concentration of 1-20%, and does not suggest a method for removing hydrogen generated during ammonia decomposition. In the case of treating ammonia / hydrogen gas by the above method, the temperature of the adsorption reactor is adjusted to an appropriate temperature (0) in order to remove high temperature unreacted ammonia gas flowing from the ammonia decomposition catalyst reactor (450-1200 ° C.) by reacting with the adsorbent. -90 ℃). As a result, a cooling device is required and the system becomes large. In addition, the method does not provide a pretreatment filter layer at the front end of the catalyst, when the particulate matter in the form of metal and metal oxides, which are catalyst poison components included in the exhaust gas, has a disadvantage that the catalyst can be easily poisoned to cause deactivation. .

The present inventors completed the present invention by developing an efficient exhaust gas purification method and apparatus using a porous filter and a catalyst while studying the exhaust gas purification method for solving the problems of the prior art.

The present invention provides a flue gas purification method containing particulate matter and ammonia / hydrogen mixed gas generated during a semiconductor manufacturing process.

The present invention provides an exhaust gas purifier equipped with a porous filter and a catalyst for removing particulate matter and ammonia / hydrogen mixed gas contained in the exhaust gas.

1 shows an exhaust gas purifying apparatus according to an embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

10: ammonia decomposition reactor 11: exhaust gas inlet

12: porous filter layer 13: catalyst layer for ammonia decomposition

14: ceramic heat storage layer 15: heater

20: residual gas treatment reactor 21: piping

22: oxidant inlet 23: catalyst layer for the residual gas treatment

24: purge gas outlet 30: water storage tank

31: Auto drain valve 32, 35: Drain

33: water injection pump 34: piping

In a first aspect, the present invention provides a method for purifying exhaust gas containing particulate matter and ammonia / hydrogen mixed gas generated during a semiconductor manufacturing process. Specifically, the present invention provides a method for purifying exhaust gas by removing particulate matter contained in exhaust gas using a porous filter and then converting the ammonia / hydrogen mixed gas of the exhaust gas into water and nitrogen using a catalyst. The purifying method of the present invention is particularly useful for purifying flue gas containing high flow rate, high concentration of ammonia / hydrogen.

During the semiconductor manufacturing process, the etching process generates corrosive gases such as Cl ₂ , HCl, BCl ₃ , F ₂ , HF, HBr, and greenhouse gases such as PFCs (CF ₄ , C4F ₈ , CHF ₃ , SF ₆ ). In SiH ₄ , Si ₂ H ₆ , SiH ₂ Cl ₂ , NH ₃ , PH ₃ is generated, and in the deposition process, exhaust gas such as BF ₃ , AsH ₃ , PH ₃ is generated. In the non-memory semiconductor manufacturing process, a mixed gas such as AsH ₃ / hydrogen, PH ₃ / hydrogen, SiH ₄ / hydrogen or SiH ₂ Cl ₂ / hydrogen is used. In particular, since a high flow rate and a high concentration of ammonia / hydrogen mixed gas are used in the nitride film manufacturing process, efficient treatment of exhaust gases having a large amount of these ammonia and hydrogen is problematic.

In the exhaust gas purification method of the present invention, the exhaust gas is passed through a porous filter to remove particulate matter, and the mixed gas from which particulate matter is removed is reacted with a catalyst for decomposing ammonia to decompose ammonia into nitrogen and hydrogen. Residual gas containing undecomposed ammonia is mixed with an oxidant and then reacted with a catalyst for treating residual gas to convert hydrogen into water and residual ammonia into water and nitrogen.

In the definition of the present invention, "exhaust gas" refers to a gaseous substance emitted during combustion, synthesis, and decomposition of a substance, and in particular, refers to a gaseous environmental pollutant emitted during a semiconductor manufacturing process or a chemical treatment process.

Before the flue gas is treated by the method of the present invention, particulate matter contained in the flue gas may optionally be removed using an adsorbent or a fibrous filter. Since the particulate matter that inhibits the catalytic reaction can be removed by the pretreatment process, the pretreatment process is not necessarily required, but it is preferable to pass through the pretreatment process.

The particulate matter is removed by passing the exhaust gas through the pre-treatment process or without the pre-treatment process through the porous filter. "Particulate matter" is a fine substance that arises from crushing, screening, depositing, transferring or other mechanical treatment or burning, synthesis, or decomposition of a substance. The particulate matter contained in the exhaust gas is an aerosol with a size of 0.001 to 1000㎛. Present in solid phase. Particulate matter contained in the flue gas is mainly metals and metal oxides, for example, B, Si, As, P and B ₂ O ₃ , SiO ₂ , As ₂ O ₃ , As ₂ O ₅ , P ₂ O ₃ , P ₂ There are O ₅ .

The porous filter for removing the particulate matter should not be limited because the air gap is large, there is no blockage due to the accumulation of particulate matter, and the contact area with the particulate matter should be used to have a high removal efficiency. For example, ceramic honeycomb, ceramic foam, and metallic foam may be used, but is not limited thereto. The porous filter may be configured as a separate reactor, but is usually used by filling the lower end of the reactor for ammonia decomposition. As a result, the contact area and the contact time between the particulate matter contained in the exhaust gas and the porous filter can be increased, and the particulate matter can be effectively removed through physical and chemical adsorption.

The flue-gas passing through the porous filter part is free of particulate matter and is contacted with a catalyst for ammonia decomposition. "Ammonia decomposition catalyst" can be used without particular limitation as long as it can decompose ammonia into hydrogen and nitrogen. As the catalyst for ammonia decomposition, a transition metal may be preferably used. Transition metals include, for example, cobalt, vanadium, molybdenum, tungsten, nickel and iron. On the other hand, when performing a decomposition reaction of ammonia at 700 degreeC or more, it is preferable to add a thermal stabilizer. 'Thermal stabilizer' may be cerium or lanthanum or the like as a material for preventing the active ingredient of the catalyst from being lost due to sintering at high temperatures.

Ammonia decomposition catalysts or ammonia decomposition catalysts and thermal stabilizers are mixed and used on a carrier having a large surface area. The carrier may be alumina, chitania, zirconia, silica, silica-alumina and zeolite, but is not limited thereto. When the catalyst for ammonia decomposition of the present invention is filled in a porous filter and one reactor, the catalyst for ammonia decomposition is preferably used after being filled on the porous filter layer of the reactor. The filling amount of the catalyst can be adjusted according to the ammonia concentration of the exhaust gas, the flow rate of the gas to be treated, the reaction temperature and the type of catalyst. In the decomposition of ammonia using a catalyst, the reaction temperature is in the range of 400 ° C to 1000 ° C and preferably 500 ° C to 800 ° C. The reaction temperature of the flue gas can be preheated and maintained by a heater mounted in a reactor for decomposition of ammonia. The space velocity (SV) of the flue gas in the reactor for ammonia decomposition is determined by the concentration of ammonia contained in the flue gas, the filling amount of the ammonia decomposition catalyst, and the reaction temperature. The SV is 10 to 100,000 h ⁻¹ , preferably 100 to It is desirable to have a range of 50,000 h ⁻¹ .

In the ammonia decomposition reactor, the exhaust gas whose temperature is raised while passing through the ammonia decomposition catalyst is recovered heat from the ceramic heat storage body and flows into the reactor for treating residual gas. The ammonia decomposition reaction is an endothermic reaction, and heat must be supplied from the outside in order to promote the reaction. The ceramic heat accumulator serves to recover heat released after the adiabatic reaction of the reactor and the reaction, thereby reducing the thermal energy supplied from the outside. I can plan driving. The ceramic heat storage body is composed of honeycomb, foam, sphere and pellet, and is characterized in that to recover the heat discharged from the catalytic reactor for ammonia decomposition.

By the above process, ammonia in the flue gas is decomposed into nitrogen and hydrogen, and in the next step, hydrogen and unreacted ammonia are converted into water and nitrogen using a catalyst for treating residual gas. "Residual gas treatment catalyst" can be used without limitation as long as it can convert hydrogen and unreacted ammonia into water or water and nitrogen, respectively. The catalyst for treating residual gas of the present invention may preferably be a metal or a metal oxide. For example, platinum, palladium, rhodium and iridium may be used as the metal, and molybdenum oxide, tungsten oxide, or vanadium oxide may be used as the metal oxide. A thermal stabilizer may be added to maintain the activity of the catalyst for treating residual gas even at high temperatures. Cerium or lanthanum may be used as the thermal stabilizer. The residual gas treating catalyst or the residual gas treating catalyst and the thermal stabilizer are mixed and used on a carrier having a large surface area. Carrier types are as described above.

The catalyst for treating residual gas of the present invention is used by filling it in a reactor for treating residual gas. The amount of filling may vary depending on the concentration of ammonia remaining in the residual gas, the reaction temperature and the catalyst used.

The residual gas containing hydrogen and residual ammonia discharged from the ammonia decomposition reactor is mixed with the oxidant and then passed through the reactor for treating residual gas. As the oxidizing agent, air, oxygen, ozone and hydrogen peroxide can be used. Hydrogen and residual gas mixed with the oxidant are effectively removed by nonflame catalysis. In the residual gas treatment, the reaction temperature is from room temperature to 800 ° C, preferably from 100 ° C to 550 ° C.

The ammonia decomposition reaction is an endothermic reaction and the decomposition efficiency increases as the reaction temperature increases. The residual gas decomposition reaction is exothermic, and as the temperature is increased, the oxidation reaction of ammonia is accelerated to increase the NOx, a by-product of the reaction. Therefore, the inventors of the present invention have set the temperature of a reactor filled with a catalyst for ammonia decomposition and a catalyst for treating residual gas in order to set an optimum temperature for reducing the concentration of nitrogen oxide as a reaction byproduct while improving the decomposition efficiency of ammonia and residual gas. Flue gas was treated with varying.

As a result, when the ammonia decomposition reactor temperature was changed from 400 to 750 ° C. and ammonia, hydrogen and nitrogen were injected at concentrations of 30 to 35%, the ammonia gas concentration at the outlet of the reactor decreased as the temperature increased. (Table 1). In addition, when ammonia, hydrogen, and nitrogen were injected at a concentration of 30 to 35% while changing the temperature of the reactor for treating residual gas from 200 to 700 ° C, the concentration of ammonia and hydrogen gas decreased with increasing temperature, but the nitrogen at the outlet of the reactor was decreased. It was found that the oxide concentration was increased (Table 2). From the above results, the present inventors fixed the temperature of the reactor for ammonia decomposition at 750 ° C., fixed the temperature of the reactor for residual gas treatment at 150 ° C., and then injected the ammonia, hydrogen, and nitrogen at a concentration of 10 to 70%. It was confirmed that the gas and hydrogen gas can be effectively removed (Table 3, Table 4).

In a second aspect the present invention provides an exhaust gas purifier equipped with a porous filter and a catalyst for the removal of particulate matter and ammonia / hydrogen mixed gas contained in the exhaust gas.

The exhaust gas purifying apparatus of the present invention includes a reactor for decomposing ammonia (10), which serves to remove particulate matter in the exhaust gas and decompose ammonia into nitrogen and hydrogen;

A reactor for treating residual gas for converting hydrogen introduced from the ammonia decomposition reactor into water and decomposing residual ammonia gas into water and nitrogen;

It is composed of a water storage tank 30 for the storage of water generated from the residual gas treatment reactor and the temperature control of the residual gas treatment reactor (FIG. 1).

The ammonia decomposition reactor 10 includes an exhaust gas inlet 11 installed at one end of the ammonia, a porous filter layer 12 filled with a porous filter at a lower end of the reactor, and an ammonia decomposition filled with a catalyst for ammonia decomposition at the top of the porous filter layer. The heater is mounted to adjust the temperature in the reactor around the ceramic heat accumulator layer 14 and the porous filter layer 12 and the catalyst layer 13 for ammonia decomposition filled with a ceramic heat accumulator on top of the catalyst layer 13 and the ammonia decomposition catalyst layer. It consists of 15). The ceramic heat storage body is configured in the form of honeycomb, foam, sphere and pellets, characterized in that for recovering the heat discharged from the catalytic reactor for ammonia decomposition.

Residual gas treatment reactor 20 is a pipe 21 connecting the ammonia decomposition reactor 10 and the residual gas treatment reactor, the oxidant inlet 22 connected to one side of the pipe and the catalyst for the residual gas treatment in the reactor It is composed of a catalyst layer 23 for treating residual gas and a purge gas outlet 24 provided at one side of the bottom of the reactor. The purge gas outlet 24 is inclined so that the water condensed in the pipe naturally falls and collects at the lower end of the reactor for treating residual gas.

The water storage tank 30 is connected to the lower end of the residual gas treatment reactor 20 and has a drain port 32 equipped with an auto drain valve 31, a reactor for ammonia decomposition 10 and a reactor for residual gas treatment 20. It is composed of a pipe 34 equipped with a water infusion pump 33 for supplying water to the pipe 21 for connecting the pipe) and a drain hole 35 provided on one side of the water storage tank 30. The auto drain valve operates automatically when the water collected at the bottom of the reactor for residual gas treatment exceeds a certain level, and transfers the water to the water storage tank through the drain. The water storage tank 30 overflows when water exceeds a predetermined level and is discharged through a drain hole connected to the water storage tank. The water injection pump 33 is automatically operated when the temperature of the residual gas treatment reactor 20 becomes 550 ° C. or more, and water stored in the water storage tank is injected into the residual gas treatment reactor to prevent overheating of the reactor.

Hereinafter, the operation of the exhaust gas purifying apparatus of the present invention will be described in detail with reference to the accompanying drawings.

The particulate matter-containing exhaust gas discharged from the semiconductor manufacturing process is filled with the porous filter layer 12, the catalyst layer for ammonia decomposition 13, and the ceramic heat storage layer 14 through the exhaust gas inlet 11 and heated by the heater 15. Pass through the reactor 10 for ammonia decomposition. At this time, the particulate matter in the form of metal and metal oxide contained in the exhaust gas is removed while passing through the porous filter layer 12, the material having a large particle size is lowered and deposited on the lower end of the reactor for ammonia decomposition by gravity. The ammonia / hydrogen mixed gas contained in the exhaust gas is preheated and passed through the catalyst layer 13 for ammonia decomposition, while ammonia is decomposed into hydrogen and nitrogen, and heat is recovered while passing through the ceramic heat storage body 14. Hydrogen and trace amounts of residual ammonia introduced from the ammonia decomposition reactor 10 through the pipe 21 are mixed with the oxidant introduced from the oxidant inlet 22, and then the residual gas filled with the catalyst for treating residual gas 23. Pass through the reactor 20 for processing. Hydrogen and residual ammonia undergo a non-flame oxidation reaction with the oxidant on the catalyst, whereby hydrogen is converted to water and residual ammonia is converted to water and nitrogen. The purified flue gas is discharged to the atmosphere through the purge gas outlet 24. Moisture contained in the purified flue gas is condensed in the pipe and falls naturally and merges with water generated through the reaction accumulated in the lower end of the reactor 20 for residual gas treatment. Is opened and stored in the water storage tank 30 through the drain 32. When the water stored in the water storage tank 30 exceeds a predetermined level, the water overflows and is discharged through the drain hole 35 connected to the water storage tank 30. The water injection pump 33 connected to the water storage tank 30 and the residual gas treatment reactor 20 and the pipe 34 operates when the residual gas treatment reactor 20 reaches 550 ° C. or higher to treat the residual gas. Injection into the reactor 20 prevents the heating of the reactor.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are illustrative of the present invention, and the content of the present invention is not limited by the examples.

<Example>

Example 1

Preparation of Ammonia Decomposition Catalyst and Residual Gas Treatment Catalyst

12 g of Co (NO ₃ ) ₂ 6H ₂ O (Duksan Chemical) was dissolved in 12.68 ml of distilled water, and 20 g of Al ₂ O ₃ carrier (Procatalyse) was added to these aqueous solutions for 12 hours of impregnation in air, and dried at 110 ° C for 12 hours. Firing at 500 ° C. for 4 hours to prepare a 13 wt% CoO / Al ₂ O ₃ catalyst for ammonia decomposition. 0.2 g of an aqueous solution of H ₂ PtCl ₆ (Pt purity 25%, Gold) was mixed in 15.85 ml of distilled water, and then 25 g of Al ₂ O ₃ carrier (Procatalyse) was impregnated in air for 12 hours. Time drying and calcining at 500 ° C. for 4 hours to prepare 0.1 wt% Pt / Al ₂ O ₃ catalyst for residual gas treatment.

Example 2-8

Purification of flue gas at different temperatures of reactor for ammonia decomposition

1 g of 13 wt% CoO / Al ₂ O ₃ of Example 1 was charged into a reactor for ammonia decomposition, and 1 g of 0.1 wt% Pt / Al ₂ O ₃ catalyst was mixed with 1 g of carbon lundum (Carbor undum, SiC) to obtain residual gas. Filled into the reactor for processing. Ammonia 30 ml / min (30%), hydrogen 35 ml / min (35%) and nitrogen 35 ml / min (35%) were mixed in a mixer and then introduced into the reactor for ammonia decomposition. In addition, 380 ml / min of air was injected into the pipe line at the outlet of the reactor for ammonia decomposition, mixed, and then passed through a reactor for treating residual gas. At this time, the reactor for treating residual gas was fixed at 100 ° C and the reaction was performed while changing the temperature of the catalytic reactor for decomposition of ammonia from 400 ° C to 750 ° C. The results are shown in Table 1.

Removal degree of flue gas according to temperature change of reactor for ammonia decomposition Example Reaction temperature (℃) Gas concentration Ammonia Decomposition Reactor Residual Gas Treatment Reactor Ammonia Decomposition Reactor Reactor Outlet Gas Concentration for Residual Gas Treatment Inlet NH ₃ Gas Concentration Outlet NH ₃ Gas Concentration NH ₃ H ₂ NOx 2 400 100 30% 16% 2.5% 0 <1 ppm 3 500 100 30% 14% 1.7% 0 <1 ppm 4 550 100 30% 5% 0.8% 0 <1 ppm 5 600 100 30% 1.8% 0.2% 0 <1 ppm 6 650 100 30% 0.19% 220 ppm 0 <1 ppm 7 700 100 30% 200 ppm 22 ppm 0 <1 ppm 8 750 100 30% 150 ppm 18 ppm 0 <1 ppm

As a result of the experiment, as the temperature of the ammonia decomposition reactor increased, the outlet ammonia gas concentration of the ammonia decomposition reactor and the residual gas treatment reactor decreased (Table 1).

Example 9-14

Purification of flue gas at different temperatures of reactor for residual gas treatment

The reactor for ammonia decomposition of Example 2-8 was fixed at 750 ° C., and the reaction was performed by changing the reactor for residual gas treatment from 200 ° C. to 700 ° C. The results are shown in Table 2.

Exhaust gas removal degree according to temperature change of reactor for residual gas treatment Example Reaction temperature (℃) Gas concentration Ammonia Decomposition Reactor Residual Gas Treatment Reactor Ammonia Decomposition Reactor Reactor Outlet Gas Concentration for Residual Gas Treatment Inlet NH ₃ Gas Concentration Outlet NH ₃ Gas Concentration NH ₃ H ₂ NOx 9 750 200 30% 145 ppm 12 ppm 0 15 ppm 10 750 300 30% 140 ppm 8 ppm 0 18 ppm 11 750 400 30% 140 ppm 6 ppm 0 23 ppm 12 750 500 30% 140 ppm 5 ppm 0 24 ppm 13 750 600 30% 140 ppm 7 ppm 0 23 ppm 14 750 700 30% 140 ppm 6 ppm 0 23 ppm

As a result of the experiment, the outlet ammonia gas concentration of the residual gas treatment reactor tended to decrease as the temperature of the residual gas treatment reactor increased. Nitrogen oxide concentrations, on the other hand, tended to increase (Table 2).

Example 15

Purification of Flue Gas Using Apparatus of the Invention

The reactor for ammonia decomposition of Example 2-8 was fixed at 750 ° C., and the reactor for residual gas treatment was fixed at 150 ° C., followed by ammonia 10 ml / min (10%), hydrogen 45 ml / min (45%), nitrogen 45 ml / min (45%) was mixed in the mixer, then introduced into the reactor for ammonia decomposition, and 286 ml / min air was injected into the reactor outlet piping line for the ammonia decomposition. The results are shown in Table 3.

Example 16

Purification of Flue Gas Using Apparatus of the Invention

The reactor for ammonia decomposition of Example 2-8 was fixed at 750 ° C., and the reactor for residual gas treatment was fixed at 150 ° C., followed by ammonia 30 ml / min (30%), hydrogen 35 ml / min (35%), nitrogen 35 ml / min (35%) was mixed in a mixer, then introduced into the reactor for ammonia decomposition, and 380 ml / min was injected into the reactor outlet piping line for the ammonia decomposition. The results are shown in Table 3.

Example 17

Purification of Flue Gas Using Apparatus of the Invention

The reactor for ammonia decomposition of Example 2-8 was fixed at 750 ° C., and the reactor for residual gas treatment was fixed at 150 ° C., followed by ammonia 50 ml / min (50%), hydrogen 25 ml / min (25%), nitrogen 25 ml / min (25%) was mixed in a mixer, and then introduced into the reactor for ammonia decomposition, and 475 ml / min was injected into the reactor outlet piping line for ammonia decomposition. The results are shown in Table 3.

Example 18

Purification of Flue Gas Using Apparatus of the Invention

Ammonia 70ml / min (70%), hydrogen 15ml / min (15%) and nitrogen 15ml / min (15%) were mixed in a mixer, and then introduced into the reactor for ammonia decomposition of Example 15, and ammonia decomposition reactor 570 ml / min was injected into the outlet pipe line and mixed. The results are shown in Table 3.

Exhaust gas removal degree using the device of the present invention Example Reaction temperature (℃) Gas concentration Ammonia Decomposition Reactor Residual Gas Treatment Reactor Ammonia Decomposition Reactor Reactor Outlet Gas Concentration for Residual Gas Treatment Inlet NH ₃ Gas Concentration Outlet NH ₃ Gas Concentration NH ₃ H ₂ NOx 15 750 150 10% 40 ppm 5 ppm 0 4 ppm 16 750 150 30% 140 ppm 15 ppm 0 10 ppm 17 750 150 50% 600 ppm 18 ppm 0 65 ppm 18 750 150 70% 950 ppm 14 ppm 0 60 ppm

Example 19

Preparation of Ammonia Decomposition Catalyst and Residual Gas Treatment Catalyst

2.38 g of Ce (C ₂ H ₃ O ₂ ) ₃ (AMR) was dissolved in 12.68 ml of distilled water, and 20 g of 13 wt% CoO / Al ₂ O ₃ was added to these aqueous solutions, which was impregnated in air for 12 hours, and dried at 110 ° C. for 12 hours. Firing at 500 ° C. for 4 hours to prepare a 3 wt% CeO ₂ -13 wt% CoO / Al ₂ O ₃ catalyst for ammonia decomposition. 2.38 g of Ce (C ₂ H ₃ O ₂ ) ₃ (AMR) was dissolved in 12.68 ml of distilled water, and then 20 g of 0.1 wt% Pt / Al ₂ O ₃ was added to these aqueous solutions, which was impregnated in air for 12 hours, and dried at 110 ° C. for 12 hours. The mixture was calcined at 500 ° C. for 4 hours to prepare a ₃ wt% CeO ₂ -0.1 wt% Pt / Al ₂ O ₃ catalyst for ammonia decomposition.

Example 20

Purification of Flue Gas Using Apparatus of the Invention

1 g of the 3 wt% CeO ₂ -13 wt% CoO / Al ₂ O ₃ catalyst of Example 17 was charged to a reactor for decomposing ammonia, and 1 g of 0.1 wt% Pt / Al ₂ O ₃ catalyst was carborundum (SiC). After mixing with 1 g, it was charged into a reactor for treating residual gas. The ammonia decomposition reactor and the reactor for treating residual gas were fixed at 750 ° C. and 150 ° C., respectively, to carry out the reaction under the same conditions as in Example 2-8. The results are shown in Table 4.

Example 21

Purification of Flue Gas Using Apparatus of the Invention

3 wt% CeO ₂ -13 wt% CoO / Al ₂ O ₃ and 3 wt% CeO ₂ -0.1 wt% Pt / Al ₂ O ₃ catalyst fired at 1000 ° C. for 4 hours, respectively The reactor was charged and reacted under the same conditions as in Example 17. The results are shown in Table 4.

Removal degree of exhaust gas using the device of the present invention Example Reaction temperature (℃) Gas concentration Ammonia Decomposition Reactor Residual Gas Treatment Reactor Ammonia Decomposition Reactor Reactor Outlet Gas Concentration for Residual Gas Treatment Inlet NH ₃ Gas Concentration Outlet NH ₃ Gas Concentration NH ₃ H ₂ NOx 20 750 150 30% 220 ppm 21 ppm 0 15 ppm 21 750 150 30% 0.2% 300 ppm 0 20 ppm

The exhaust gas purification method of the present invention can effectively remove the particulate matter contained in the exhaust gas by using a porous filter to prevent deactivation of the catalyst due to particulate matter, and by removing the high flow rate, high concentration ammonia / hydrogen mixed gas using the catalyst It can improve the safety and continuous operation of operation.

Claims (18)

Adsorbing and removing particulate matter contained in exhaust gas with a porous filter; Reacting the resulting mixed gas with at least one catalyst for ammonia decomposition under heating to decompose ammonia into nitrogen and hydrogen; And the resulting residual gas containing hydrogen and residual ammonia is mixed with an oxidant and reacted with a catalyst for the residual gas treatment to convert hydrogen into water and residual ammonia into water and nitrogen. The exhaust gas purification method according to claim 1, wherein the porous filter is selected from ceramic honeycomb, ceramic foam and metallic foam. The method of claim 1, wherein the catalyst for decomposing ammonia is selected from cobalt, vanadium, molybdenum, tungsten, nickel and iron. The exhaust gas purification method according to claim 1, wherein the catalyst for ammonia decomposition and the thermal stabilizer are mixed and used. The exhaust gas purification method according to claim 1, wherein the catalyst for ammonia decomposition or the catalyst for ammonia decomposition and the thermal stabilizer are supported by being used on any one selected from alumina, chitania, zirconia, silica, silica-alumina, and zeolite. . The method of claim 1, wherein the oxidizing agent is any one selected from air, oxygen, ozone, and hydrogen peroxide. The method of claim 1, wherein the catalyst for treating residual gas is a metal selected from platinum, palladium, rhodium, and iridium or a metal oxide selected from molybdenum oxide, tungsten oxide, and vanadium oxide. The exhaust gas purification method according to claim 1, wherein a catalyst for treating residual gas and a thermal stabilizer are mixed and used. The exhaust gas according to claim 1, wherein the catalyst for treating residual gas, the catalyst for treating residual gas, and the thermal stabilizer are used by being supported on any one selected from alumina, chitania, zirconia, silica, silica-alumina or zeolite. Purification Method. Reactor 10 for ammonia decomposition; Reactor 20 for processing residual gas; And Flue gas purification apparatus, characterized in that consisting of a water storage tank (30). The method of claim 10, wherein the ammonia decomposition reactor 10, An exhaust gas inlet 11 provided at one side of the lower end; A porous filter layer 12 filled at the bottom of the reactor; An ammonia decomposition catalyst layer 13 filled with a catalyst for ammonia decomposition at the top of the porous filter layer; A ceramic heat accumulator layer (14) filled with a ceramic heat accumulator on top of the catalyst layer for decomposing ammonia; And Flue gas purification device, characterized in that consisting of a heater (15) mounted for controlling the temperature in the reactor around the porous filter layer (12) and the catalyst layer for ammonia decomposition (13). The exhaust gas purifying apparatus according to claim 11, wherein the ceramic heat storage body is configured in the form of honeycomb, foam, sphere and pellet, and recovers heat discharged from the catalytic reactor for decomposing ammonia. The reactor for treating residual gas 20 according to claim 10, wherein An oxidant injection port 22 connected to one side of the pipe; Residual gas treatment catalyst layer 23 is filled with a catalyst for the residual gas treatment in the reactor; And Exhaust gas purification apparatus, characterized in that consisting of a purge gas outlet 24 provided on one side of the reactor. The exhaust gas purifying apparatus according to claim 13, wherein the purge gas discharge port is inclined so that water condensed in the pipe naturally falls and collects at the lower end of the reactor for treating residual gas. The water storage tank (30) of claim 10, wherein A drain port 32 connected to the lower end of the reactor 20 for treating residual gas and equipped with an auto drain valve 31; A pipe 34 equipped with a water injection pump 33 for supplying water to a pipe connecting the ammonia decomposition reactor 10 and the residual gas treatment reactor 20; And Exhaust gas purification device, characterized in that consisting of a drain 35 is installed on one side of the water storage tank (30). The exhaust gas purifying apparatus according to claim 15, wherein the auto drain valve operates automatically when the water collected at the lower end of the residual gas treatment reactor exceeds a predetermined level, and transfers the water to the water storage tank through the drain port. The exhaust gas purifying apparatus according to claim 15, wherein the water storage tank overflows when water exceeds a predetermined level and is discharged through a drain hole connected to the water storage tank. The method of claim 15, wherein the water injection pump is automatically operated when the temperature of the residual gas treatment reactor is 550 ℃ or more, to inject water stored in the water storage tank into the residual gas treatment reactor to prevent overheating of the reactor. Flue gas purification device characterized in that.