JP2007083161A - Exhaust gas treatment catalyst, exhaust gas treatment method and exhaust gas treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas treatment catalyst capable of further efficiently reducing SO<SB>3</SB>or NO<SB>x</SB>contained in an exhaust gas. <P>SOLUTION: The exhaust gas treatment catalyst for removing nitrogen oxide and sulfur trioxide contained in the exhaust gas comprise at least one kind of an independent oxide of titania and silica or a composite oxide of both of titania and silica. A carrier having gold supported thereon is applied to the surface of a base material not only to suppress the decomposition reaction of ammonia caused by gold but also to accelerate the reduction reaction of sulfur trioxide in sulfur oxide in the exhaust gas and the reduction reaction of nitrogen oxide in the exhaust gas to further reduce the concentration of sulfur trioxide and the concentration of nitrogen oxide. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to an exhaust gas treatment catalyst, an exhaust gas treatment method, and an exhaust gas for removing nitrogen oxide (NOx) and sulfur trioxide (SO ₃ ) contained in exhaust gas discharged from a vehicle having a diesel engine, a gas turbine, a combustion furnace, and the like. Exhaust gas treatment catalyst that can reduce SO ₃ concentration and NOx concentration contained in exhaust gas, and is useful for exhaust gas treatment of boilers that burn high-sulfur coal or heavy oil as fuel The present invention relates to an exhaust gas treatment method and an exhaust gas treatment apparatus.

As a method for removing nitrogen oxides (NOx) in exhaust gas discharged from boilers, gas turbines, combustion furnaces, etc., ammonia (NH ₃ ) in the presence of a nitrogen oxide removal catalyst (hereinafter abbreviated as “denitration catalyst”). ) Is used as a reducing agent, and an ammonia catalytic reduction method in which NOx is decomposed into harmless nitrogen and water has been put into practical use.

Some of the boilers and the like use coal having a high sulfur content or C heavy oil as fuel. High concentrations of sulfur dioxide (SO ₂ ) and sulfur trioxide (SO ₃ ) exist in the exhaust gas produced by burning such fuel. When treating such exhaust gas, an NOx reduction and removal reaction that reduces and removes NOx, simultaneously with an oxidation reaction from SO ₂ to sulfur trioxide (SO ₃ ), increases SO _{3 in} the exhaust gas. To do. This SO ₃ and unreacted NH ₃ used as a reducing agent in the NOx reduction and removal reaction are easily combined in a low temperature region to produce a compound such as acidic ammonium sulfate. This acidic ammonium sulfate compound and SO ₃ corrode the inside and piping of various devices such as heat exchangers arranged in the downstream, resulting in clogging, partial blockage, etc. and increasing pressure loss. . Therefore, it is necessary to take measures such as improving the dust collection capability of the dust collector.

As a denitration catalyst having excellent denitration performance and low SO ₂ oxidation ability that hardly causes oxidation reaction from SO ₂ to SO ₃ , a catalyst in which tungsten oxide or vanadium oxide-tungsten oxide is supported on titania is used. Are known.

Japanese Patent Laid-Open No. 10-249163 Japanese Patent Laid-Open No. 11-264759

However, it is known that even when such a denitration catalyst is used, an oxidation reaction from SO ₂ to SO ₃ occurs in the order of 0.1%. It is desired that the oxidation reaction from SO ₂ to SO ₃ occurring simultaneously with the denitration reaction is zero, and further, it is desired to reduce the SO ₃ concentration in the exhaust gas. For example, the invention described in Patent Document 1 and Various techniques such as the invention described in Patent Document 2 have been proposed.

Therefore, the present invention has been proposed in view of the above circumstances, and is an exhaust gas that is a starting material of S material containing acidic ammonium sulfate and the like that causes deterioration in the performance of the catalyst and corrosion of the device disposed downstream of the catalyst. It is an object of the present invention to provide an exhaust gas treatment catalyst, an exhaust gas treatment method, and an exhaust gas treatment device that more efficiently reduce the coexisting SO ₃ and NOx and further suppress the generation of SO ₃ in the catalyst itself.

  The exhaust gas treatment catalyst according to the first invention for solving the above-mentioned problem is an exhaust gas treatment catalyst for removing nitrogen oxides and sulfur trioxide contained in the exhaust gas, wherein at least one single oxide of titania or silica or It is characterized in that it is made of these complex oxides and is coated on a surface of a substrate with a carrier carrying gold.

  An exhaust gas treatment catalyst according to a second invention that solves the above-described problem is the exhaust gas treatment catalyst described in the first invention, characterized in that the carrier contains tungsten oxide.

  An exhaust gas treatment catalyst according to a third invention for solving the above-described problem is the exhaust gas treatment catalyst described in the first or second invention, wherein the base material is a titania-tungsten oxide denitration catalyst, cordierite, Or it is mullite.

  An exhaust gas treatment catalyst according to a fourth invention for solving the above-mentioned problem is the exhaust gas treatment catalyst described in the third invention, wherein the tungsten oxide of the base material is 100 parts by weight of titania of the base material. 0.1 to 25 parts by weight.

  An exhaust gas treatment method according to a fifth invention for solving the above-described problem is an exhaust gas treatment method for removing nitrogen oxides and sulfur trioxide contained in the exhaust gas, and is described in any one of the first to fourth inventions. The exhaust gas to which ammonia has been added is brought into contact with the exhaust gas treatment catalyst so as to reduce the sulfur trioxide and reduce the nitrogen oxides.

  An exhaust gas treatment apparatus according to a sixth invention for solving the above-described problem is an exhaust gas treatment apparatus that removes nitrogen oxides and sulfur trioxide contained in exhaust gas, and is disposed in contact with the exhaust gas to which ammonia is added. The exhaust gas treatment catalyst according to any one of the first to fourth inventions, and a denitration catalyst disposed downstream of the exhaust gas treatment catalyst, wherein the sulfur trioxide is reduced by the exhaust gas treatment catalyst. The nitrogen oxide is reduced, and the nitrogen oxide is further reduced by the denitration catalyst.

  According to the exhaust gas treatment catalyst according to the first invention, the gold supported on the carrier is appropriately applied to the surface of the substrate, and the substrate to which the carrier is applied is treated with sulfur oxide and nitrogen oxidation. The decomposition reaction of the ammonia by the gold is suppressed by contacting with the exhaust gas containing the substance and ammonia is added, and the sulfur trioxide reduction reaction among the sulfur oxides contained in the exhaust gas and contained in the exhaust gas Since the reduction reaction of the nitrogen oxide is promoted, the concentration of sulfur trioxide and the concentration of nitrogen oxide can be reduced.

  According to the exhaust gas treatment catalyst according to the second aspect of the invention, the same effect as the exhaust gas treatment catalyst described in the first aspect of the invention can be obtained, and the denitration performance can be further improved.

  According to the exhaust gas treatment catalyst according to the third aspect of the invention, the same effect as the exhaust gas treatment catalyst described in the first or second aspect of the invention can be obtained, and the substrate coated with the carrier is made of sulfur oxide and nitrogen. The sulfur trioxide is brought into contact with the exhaust gas containing ammonia and added, and the sulfur trioxide reduction reaction contained in the exhaust gas and the nitrogen oxide reduction reaction contained in the exhaust gas are promoted. And the nitrogen oxide concentration can be further reduced.

  According to the exhaust gas treatment catalyst of the fourth invention, the same effect as the exhaust gas treatment catalyst described in the third invention is exhibited, and the substrate coated with the carrier is treated with sulfur oxide and nitrogen oxide. The sulfur trioxide contained in the exhaust gas and the reduction reaction of nitrogen oxide contained in the exhaust gas are promoted, so that the concentration of sulfur trioxide and The nitrogen oxide concentration can be further reduced.

  According to the exhaust gas treatment method of the fifth aspect of the present invention, there is provided an exhaust gas treatment method for removing nitrogen oxides and sulfur trioxide contained in the exhaust gas, wherein the exhaust gas treatment according to any of the first to fourth aspects of the invention is performed. By contacting the exhaust gas with ammonia added to the catalyst to reduce the sulfur trioxide and reducing the nitrogen oxides, the concentration of sulfur trioxide contained in the exhaust gas and contained in the exhaust gas The concentration of nitrogen oxides can be reduced.

  According to the exhaust gas treatment apparatus of the sixth invention, the exhaust gas treatment apparatus removes nitrogen oxides and sulfur trioxide contained in the exhaust gas, and is disposed in contact with the exhaust gas to which ammonia has been added. The exhaust gas treatment catalyst according to any one of the fourth invention and a denitration catalyst disposed downstream of the exhaust gas treatment catalyst, wherein the exhaust gas treatment catalyst reduces the sulfur trioxide and the nitrogen oxidation The nitrogen oxides contained in the exhaust gas and the nitrogen oxides contained in the exhaust gas can be reduced by reducing the product and further reducing the nitrogen oxide with the denitration catalyst. Thus, it is possible to reduce the size and cost of the exhaust gas treatment device.

The best mode for carrying out the exhaust gas treatment catalyst, the exhaust gas treatment method and the exhaust gas treatment device according to the present invention will be described below.
FIG. 1 is a schematic view of an exhaust gas treatment apparatus according to an embodiment of the present invention.

The exhaust gas treatment catalyst according to an embodiment of the present invention uses (adds) ammonia as a reducing agent and is discharged from a boiler, a gas turbine, a combustion furnace, a vehicle having a diesel engine, and the like. _{X 3} ) and SO ₃ can be removed from the exhaust gas containing nitrogen oxide (NOx) (see the following formula (1)) and NOx can be removed (see the following formulas (3) and (4)).

Furthermore, the upper layer (surface) of the base material made of a titania-tungsten oxide denitration catalyst is coated with a carrier carrying gold and comprising at least one single oxide of titania or silica or a composite oxide thereof. By using an exhaust gas treatment catalyst, the gold supported on the carrier is appropriately applied to the surface of the substrate, and an oxidizing action from SO ₂ to SO ₃ in the exhaust gas (the following equation (2) is expressed) Reference) is suppressed, and the reduction reaction from SO ₃ to SO ₂ and the reduction reaction of nitrogen oxides contained in the exhaust gas are promoted. Therefore, the concentration of sulfur trioxide contained in the exhaust gas and the concentration of nitrogen oxide contained in the exhaust gas can be reduced.

SO ₃ + 2NH ₃ + O ₂ → SO ₂ + N ₂ + 3H ₂ O (1)
2SO ₂ + O ₂ → 2SO ₃ (2)
4NO + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O (3)
NO + NO ₂ + 2NH ₃ → 2N ₂ + 3H ₂ O (4)

  As a carrier for supporting gold, at least one single oxide of titanium or silica, or a composite oxide thereof can be used. Further, the denitration performance can be further improved by adding tungsten oxide to the carrier.

Gold supported as an active metal has an activity of 0.02 part by weight or more, preferably 0.1 part by weight or more, and high activity with respect to 100 parts by weight of the carrier. That is, by making the amount of gold supported on the carrier within the above range, the reduction reaction from SO ₃ to SO ₂ and the reduction reaction of nitrogen oxides contained in the exhaust gas are promoted. The method for supporting gold on the carrier can be carried out by a spray drying method if the carrier is in powder form, and can be carried out by an impregnation method if the carrier is formed into a honeycomb type or granular shape. .

The titania-tungsten oxide denitration catalyst used as the substrate has a tungsten oxide content of 0.1 to 25 parts by weight with respect to 100 parts by weight of titania. When the tungsten oxide amount of the base material has the above-mentioned parts by weight, the exhaust gas treatment catalyst is brought into contact with the exhaust gas containing sulfur oxides and nitrogen oxides and added with ammonia. The nitrogen oxide can be more significantly reduced.
Further, in the vicinity of mobile sources such as automobiles, in order to avoid damage to the catalyst due to vibration, strength superior cordierite _{(2MgO · 2Al 2 O 3 ·} 5SiO 2) or mullite _{(3Al 2 O 3 · 2SiO 2} ) Etc. are used as the substrate.

As shown in FIG. 1, the exhaust gas treatment apparatus 3 according to an embodiment of the present invention includes the above-described exhaust gas treatment catalyst 1 and a denitration catalyst 2 arranged in series with the exhaust gas treatment catalyst 1. Ammonia 5 is added to the exhaust gas 4. The exhaust gas treatment catalyst 1 is disposed in contact with the exhaust gas 4 to which ammonia 5 is added, and the denitration catalyst 2 is disposed on the downstream side of the exhaust gas treatment catalyst 1. As the denitration catalyst 2, a conventionally used catalyst is used. By circulating the exhaust gas 4 to which ammonia 5 has been added to the exhaust gas treatment device 3, the oxidizing action from SO ₂ to SO ₃ in the exhaust gas 4 is suppressed, and the reduction treatment and denitration from SO ₃ to SO ₂ in the exhaust gas 4 are suppressed. Processing is performed simultaneously. That is, SO ₃ in the exhaust gas 4 is reduced by the exhaust gas treatment catalyst 1 to generate SO ₂ , NOx in the exhaust gas 4 is reduced to generate nitrogen, and NOx in the exhaust gas 4 is reduced by the denitration catalyst 2. Further reduction produces nitrogen.

  Therefore, since the concentration of sulfur trioxide contained in the exhaust gas and the concentration of nitrogen oxide contained in the exhaust gas can be sufficiently reduced with one exhaust gas treatment device 3, the size of the exhaust gas treatment device 3 can be reduced. And cost reduction can be achieved.

[Catalyst preparation method 1]
Spherical titania (diameter: 2 mm to 4 mm) with respect to, chloroauric acid (HAuCl ₄₎ solution was impregnated into, for example, chloroauric acid the Au concentration was adjusted to 40g / L (HAuCl ₄₎ was impregnated for one minute in the solution, The titania was impregnated with 1 part by weight of Au per 100 parts by weight of titania. For example, when the water content of spherical titania is 0.25 mL per gram of titania, the concentration of the chloroauric acid solution is calculated as follows to impregnate and support 1 part by weight of gold to 100 parts by weight of spherical titania.

Therefore, by impregnating spherical titania with a solution in which the gold concentration in the chloroauric acid (HAuCl ₄ ) solution is adjusted to 40 g / L for 1 minute, 1 part by weight of gold is impregnated with respect to 100 parts by weight of spherical titania. .
Subsequently, the spherical titanium impregnated and supported with gold was dried and then fired at 500 ° C. for 5 hours.

  Water was added to the titania-gold spherical catalyst, and the mixture was pulverized with a wet ball mill to obtain a slurry for coating (No. 1).

  Next, a titania-tungsten oxide honeycomb type catalyst (5.9 mm pitch, wall thickness 1.0 mm) used as a base material, a so-called titania-tungsten oxide denitration catalyst is immersed in the slurry (No. 1), and this catalyst is used. And dried at 500 ° C. for 5 hours.

A coating amount of the powder slurry thus fired was applied in an amount of 100 g per 1 m ² of the surface area of the substrate, and the resulting honeycomb catalyst was used as an exhaust gas treatment catalyst (No. 1).

[Catalyst preparation method 2]
Powdered titania (manufactured by Ishihara Sangyo Co., Ltd.) and chloroauric acid (HAuCl ₄ ) solution were mixed to prepare a slurry, which was then spray-dried (spray-dried) to give 1 per 100 parts by weight of titania powder. A part by weight of gold was supported on the powder and fired at 500 ° C. for 5 hours.

  Water was added to the titania-gold powder catalyst and pulverized with a wet ball mill to obtain a slurry for coating (No. 2).

  Hereinafter, the same operation as in the catalyst adjustment method 1 was performed, and the obtained honeycomb catalyst was used as an exhaust gas treatment catalyst (No. 2).

[Catalyst preparation method 3]
Powder silica (manufactured by Fuji Silysia Chemical Co., Ltd.) and chloroauric acid (HAuCl ₄ ) solution were mixed to prepare a slurry, and then this slurry was spray-dried (spray-dried) to obtain 1 per 100 parts by weight of silica powder. A part by weight of gold was supported on the powder and fired at 500 ° C. for 5 hours.

  Water was added to the silica-gold powder catalyst and pulverized by a wet ball mill to obtain a coating slurry (No. 3).

  Hereinafter, the same operation as in the catalyst adjustment method 1 was performed, and the obtained honeycomb catalyst was used as an exhaust gas treatment catalyst (No. 3).

[Catalyst preparation method 4]
1,126 g of tetraisopropyl orthotitanate (Nihon Soda Co., Ltd., Ti (OiC ₃ H ₇ ) ₄ ) and 57.6 g of tetraethyl orthosilicate (Tama Chemical Co., Ltd., Si (OC ₂ H ₅ ) ₄ ) were mixed. The mixture was added to 80 ° C. hot water in another container, and the mixture was stirred for 2 hours to hydrolyze the TiO ₂ and SiO ₂ raw materials to obtain a slurry containing TiO ₂ —SiO ₂ hydroxide. . Thereafter, the slurry was filtered, dried, and then fired at 500 ° C. for 5 hours to obtain a composite oxide powder of TiO ₂ —SiO ₂ composed of 95 parts by weight of TiO ₂ and 5 parts by weight of SiO ₂ (No. 1 ) Was adjusted.

A composite oxide powder (No. 1) and a chloroauric acid (HAuCl ₄ ) solution were mixed to prepare a slurry, which was then spray-dried (spray-dried) to give 100 parts by weight of titania-silica powder. 1 part by weight of gold was supported on the powder and fired at 500 ° C. for 5 hours.

  Water was added to the titania-silica-gold powder catalyst and pulverized with a wet ball mill to obtain a slurry for coating (No. 4).

  Hereinafter, the same operation as in the catalyst preparation method 1 was performed, and the obtained honeycomb catalyst was used as an exhaust gas treatment catalyst (No. 4).

[Catalyst preparation method 5]
A honeycomb-type catalyst containing 9 parts by weight of tungsten oxide (WO ₃ ) per 100 parts by weight of titania (TiO ₂ ) is impregnated with a chloroauric acid (HAuCl ₄ ) solution to give 100 parts by weight of titania-oxidation. The catalyst was impregnated with 1 part by weight of gold per tungsten catalyst. Subsequently, the titania-tungsten oxide catalyst impregnated and supported by gold was dried and then calcined at 500 ° C. for 5 hours.

  This titania-tungsten oxide-gold honeycomb type catalyst was adjusted to 10 mm or less with a crusher, further added with water and pulverized with a wet ball mill to obtain a coating slurry (No. 5).

  Hereafter, it operated similarly to the catalyst adjustment method 1, and the obtained honeycomb type catalyst was made into the exhaust gas treatment catalyst (No. 5).

[Catalyst preparation method 6]
A honeycomb-type catalyst containing 9 parts by weight of tungsten oxide (WO ₃ ) per 100 parts by weight of titania (TiO ₂ ) is impregnated with a chloroauric acid (HAuCl ₄ ) solution to give 100 parts by weight of titania-oxidation. The catalyst was impregnated with 2 parts by weight of gold per tungsten catalyst. Subsequently, the titania-tungsten oxide catalyst impregnated and supported by gold was dried and then calcined at 500 ° C. for 5 hours.

  This titania-tungsten oxide-gold honeycomb type catalyst was adjusted to 10 mm or less with a crusher, further added with water and pulverized with a wet ball mill to obtain a coating slurry (No. 6).

  Hereinafter, the same operation as in the catalyst adjustment method 1 was performed, and the obtained honeycomb catalyst was used as an exhaust gas treatment catalyst (No. 6).

[Catalyst preparation method 7]
Composite oxide powder obtained by the same procedure as catalyst preparation method 4 (No.1) 1000 g and 10% ammonium paratungstate methylamine solution _{1L ((NH 4) 10 W} 12 O 41 · 5H 2 O) After mixing the solution in which 101.3 g was dissolved, 3 L of water was further added and mixed to prepare a slurry. This slurry was spray-dried (spray-dried), loaded with 9 parts by weight of tungsten oxide (WO ₃ ) per 100 parts by weight of the composite oxide powder (No. 1), and fired at 500 ° C. for 5 hours.

Subsequently, a TiO ₂ —SiO ₂ —WO ₃ powder and a chloroauric acid (HAuCl ₄ ) solution were mixed to prepare a slurry, which was then spray-dried (spray dried) to obtain 100 parts by weight of titania- 1 part by weight of gold per silica-tungsten oxide powder was supported on the powder and fired at 500 ° C. for 5 hours. Water was added to the titania-silica-tungsten oxide-gold powder catalyst and pulverized with a wet ball mill to obtain a slurry for coating (No. 7).

  Hereinafter, the same operation as in the catalyst preparation method 1 was performed, and the obtained honeycomb catalyst was used as an exhaust gas treatment catalyst (No. 7).

[Catalyst preparation method 8]
A cordierite honeycomb (4.2 mm pitch, wall thickness 0.6 mm) used as a substrate is dipped in the slurry for coating (No. 6) obtained by the catalyst preparation method 6, and the catalyst is dried and then heated to 500 ° C. And baked for 5 hours.

100 g of the coating amount of the powder slurry thus fired was applied per 1 m ² of the surface area of the substrate, and the resulting honeycomb catalyst was used as an exhaust gas treatment catalyst (No. 8).

(Comparative Example 1)
[Comparative Catalyst Preparation Method 1]
A honeycomb type catalyst (TiO ₂ -WO ₃ honeycomb type catalyst) containing 9 parts by weight of tungsten oxide (WO ₃ ) per 100 parts by weight of titania (TiO ₂ ) is impregnated with a chloroauric acid (HAuCl ₄ ) solution. The catalyst was then impregnated with 1 part by weight of gold per 100 parts by weight of titania-tungsten oxide catalyst. Subsequently, the titania-tungsten oxide catalyst impregnated and supported by gold was dried and then calcined at 500 ° C. for 5 hours.

  The honeycomb catalyst thus fired was used as a comparative exhaust gas treatment catalyst (No. 1).

(Comparative Example 2)
[Comparative Catalyst Preparation Method 2]
A honeycomb type catalyst containing 9 parts by weight of tungsten oxide (WO ₃ ) per 100 parts by weight of titania (TiO ₂ ) was used as a comparative exhaust gas treatment catalyst (No. 2).

(Comparative Example 3)
[Comparative Catalyst Preparation Method 3]
A honeycomb type catalyst containing 9 parts by weight of tungsten oxide (WO ₃ ) and 0.7 parts by weight of vanadium pentoxide (V ₂ O ₅ ) per 100 parts by weight of titania (TiO ₂ ) was compared with a comparative exhaust gas treatment catalyst (No .3).

[Measurement of SO ₃ reduction performance and denitration performance]
Each of the exhaust gas treatment catalysts (No. 1 to No. 7) and the comparative exhaust gas treatment catalysts (No. 1 to No. 3) has the shape shown in Table 1, that is, 30 mm (5 holes) × 30 mm (5 holes) × 462 mm long The catalyst for the exhaust gas treatment catalyst No. 8 is formed into a catalyst having a length of 30 mm (7 holes) × 30 mm (7 holes) × 317 mm, and the two catalysts thus formed are connected in series. With respect to the exhaust gas treatment catalyst (No. 1 to No. 8) and the comparative exhaust gas treatment catalyst (No. 1 to No. 3) having such a shape, the exhaust gas was circulated under the conditions shown in Table 1 below. At the first outlet of the catalyst (AV = 42.74 (m ³ N / m ² · h)) and at the second outlet (AV = 21.37 (m ³ N / m ² · h)), the SO ₃ reduction rate and denitration In Table 1, Ugs represents a superficial velocity (fluid flow rate / flow channel cross-sectional area), and AV represents an area velocity (gas amount / total contact area with catalyst).

The measurement results according to Table 1 are shown in Table 2 below.
In Table 2, the SO ₃ reduction rate and the denitration rate are respectively expressed by the following formulas.
SO ₃ reduction rate (%) = (1−outlet SO ₃ concentration / inlet SO ₃ concentration) × 100
Denitration rate (%) = (1−Outlet NOx concentration / Inlet NOx concentration) × 100

From the results shown in Table 2 above, the current denitration catalysts (Comparative exhaust gas treatment catalysts No. 2 and No. 3) have a negative SO ₃ reduction performance, that is, SO ₂ is oxidized to SO _3. It has been found that the exhaust gas treatment catalyst according to the present invention has SO ₃ reduction performance and denitration performance. From the measurement results of the exhaust gas treatment catalyst (No. 1, No. 2, No. 3, No. 4), as a carrier supporting gold, at least one single oxide of titania or silica, or a composite oxide thereof It was found that (a composite oxide of titania-silica) works effectively. From the measurement results of the exhaust gas treatment catalyst (No. 1, No. 5) and the measurement result of the exhaust gas treatment catalyst (No. 4, No. 7), the support of titania and titania-silica contains tungsten oxide (WO ₃ ). As a result, it was found that the SO ₃ reduction performance and the denitration performance were improved.

Further, from the measurement results of the exhaust gas treatment catalyst (No. 5) and the comparative exhaust gas treatment catalyst (No. 1), even if the catalyst component is the same titanium-tungsten-gold, the comparative exhaust gas treatment catalyst (No. 1) SO ₃ reduction performance of the catalyst 1 -th exit was found to exceed than SO ₃ reduction performance of the two first outlet catalyst.

This is because, in the catalyst supporting gold, the former is faster in the rate of denitration reaction and the rate of SO ₃ reduction performance, and the denitration reaction is completed on the catalyst surface, so the NH ₃ concentration decreases inside the catalyst. it is conceivable that. Therefore, with such a decrease in NH ₃ concentration, the ability to reduce SO ₃ to SO ₂ becomes lower than the ability to convert SO ₂ to SO ₃ . Therefore, it was found that in the comparative exhaust gas treatment catalyst (No. 1), gold exists inside the catalyst and the SO ₃ concentration apparently increases.

From the measurement results of the exhaust gas treatment catalyst (No. 6) and the exhaust gas treatment catalyst (No. 8), even if the coated catalyst powder is the same, the difference in SO ₃ reduction performance and the difference in denitration performance depends on the type of substrate. It was found that

The present invention relates to an exhaust gas treatment catalyst, an exhaust gas treatment method, and an exhaust gas for removing nitrogen oxide (NOx) and sulfur trioxide (SO ₃ ) contained in exhaust gas discharged from a vehicle having a diesel engine, a gas turbine, a combustion furnace, and the like. It can be used for treatment equipment, and it can reduce SO ₃ concentration and NOx concentration contained in exhaust gas, and is applicable to boiler exhaust gas treatment that burns coal with high sulfur content or heavy oil as fuel. Therefore, it can be used for a useful exhaust gas treatment catalyst, exhaust gas treatment method and exhaust gas treatment apparatus.

1 is a schematic view of an exhaust gas treatment apparatus according to an embodiment of the present invention.

Explanation of symbols

1 Exhaust gas treatment catalyst 2 Denitration catalyst 3 Exhaust gas treatment device 4 Exhaust gas 5 Ammonia

Claims (6)

An exhaust gas treatment catalyst for removing nitrogen oxides and sulfur trioxide contained in exhaust gas,
An exhaust gas treatment catalyst characterized by comprising a support carrying gold supported on a surface of a substrate, which is made of at least one single oxide of titania or silica or a composite oxide thereof. The exhaust gas treatment catalyst according to claim 1, wherein the carrier contains tungsten oxide. The exhaust gas treatment catalyst according to claim 1 or 2, wherein the base material is a titania-tungsten oxide denitration catalyst, cordierite, or mullite. The exhaust gas treatment catalyst according to claim 3, wherein the tungsten oxide of the base is 0.1 to 25 parts by weight with respect to 100 parts by weight of titania of the base. An exhaust gas treatment method for removing nitrogen oxides and sulfur trioxide contained in exhaust gas,
The exhaust gas obtained by adding ammonia to the exhaust gas treatment catalyst according to any one of claims 1 to 4 is contacted to reduce the sulfur trioxide and reduce the nitrogen oxides. Exhaust gas treatment method. An exhaust gas treatment apparatus for removing nitrogen oxides and sulfur trioxide contained in exhaust gas,
The exhaust gas treatment catalyst according to any one of claims 1 to 4, which is disposed in contact with the exhaust gas to which ammonia has been added, and a denitration catalyst disposed downstream of the exhaust gas treatment catalyst, An exhaust gas treatment apparatus, wherein the sulfur trioxide is reduced by an exhaust gas treatment catalyst, the nitrogen oxide is reduced, and the nitrogen oxide is further reduced by the denitration catalyst.

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