JP2008284506A - Catalyst for cleaning exhaust gas, its manufacturing method and method for treating exhaust gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst which has both of high denitration performance and the performance of removing unreacted NH<SB>3</SB>at high temperature of 400-600°C and by which CO can also be removed. <P>SOLUTION: An oxidation catalyst layer having an oxidation catalyst component 2 is formed by depositing oxidation catalyst paste or slurry on a belt-like region which has the width of <1/2 of that of a belt-like base material 5 and extends to the longitudinal direction of the base material along one end of the base material in the width direction. A denitration catalyst layer having a denitration catalyst component 3 is formed by depositing denitration catalyst paste or slurry on the whole surface of the oxidation catalyst layer-formed base material including the surface of the oxidation catalyst layer. A projecting part 10 having the ridgeline inclining toward the longitudinal direction of the denitration catalyst layer-formed base material 7' by 0-90° angle is formed repeatedly on the base material 7' at regular intervals. The projecting part 10-formed base material is cut to obtain catalytic elements 11. The obtained catalytic elements 11 are layered successively while being alternately turned upside down. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an exhaust gas purification technology, and in particular, an exhaust gas purification catalyst for removing NOx and CO contained in a high temperature exhaust gas of 400 ° C. or higher, such as a gas turbine, a gas engine, a diesel engine facility, etc. It relates to the processing method.

  In order to make up for the shortage of electric power and to cope with the peak of electric power consumption, so-called simple cycle gas turbines that construct gas turbines and operate independently, small-scale gas engines for industrial use, and diesel engines are increasing. Equipment used for these is often built in the suburbs of cities, and it is necessary to efficiently decompose and purify nitrogen oxides (NOx), which are harmful gases contained in exhaust gas.

In recent years, environmental regulations have been strengthened, and not only NOx, but also ammonia (NH ₃ ) added for removal of carbon monoxide (CO) contained in the exhaust gas by several tens of ppm and reduction removal (denitration) of NOx. ), Advanced treatment of exhaust gas such as prevention of unreacted ammonia outflow not used for denitration is required.

As a technology for removing NOx and CO in exhaust gas, especially in HRSG (Heat Recovery Steam Generator Exhaust Heat Recovery Boiler), a method of removing CO and NOx by installing an oxidation catalyst as CO removal before the denitration catalyst is adopted. ing. However, in this method, since an expensive oxidation catalyst must be installed, as a catalyst for improving this, a catalyst capable of simultaneously removing NOx and CO having an oxidation function in a denitration catalyst has been proposed. These do not require the installation of an oxidation catalyst, and NOx and CO can be removed using only a denitration catalyst. Therefore, a compact exhaust gas treatment facility can be used for small-scale power generation facilities with limited installation space, such as gas engines and gas turbines. Can be provided. Further, like Patent Document 1, using a denitration catalyst which gave function of decomposing NH _3, increase the denitrification rate by the addition of NH ₃ excess in NO / NH ₃ molar ratio of 1 or more, involved in denitrification A method for decomposing unreacted NH ₃ that has not been proposed has been proposed.

JP 05-146634 A Japanese Patent Application Laid-Open No. 07-016462 JP 2005-111330 A JP 2004-267969 A

That is, the above-described catalyst is characterized in that an oxidation catalyst component containing several ppm to several tens of ppm of noble metal is present sparsely in the denitration catalyst component, but in a high temperature range of 400 ° C. or higher, The oxidation ability becomes very high. Therefore, even if only a few ppm is present in the denitration catalyst, the rate at which NH ₃ is oxidized to NOx increases, resulting in a problem that the denitration performance decreases.

As a means for preventing such an adverse effect of the oxidation catalyst, a two-layer coated catalyst in which an oxidation catalyst layer is supported on a catalyst carrier and a denitration catalyst layer is supported on the surface layer has been proposed (see Patent Document 2). In this method, since the exhaust gas reaches the oxidation catalyst layer after passing through the denitration catalyst layer on the catalyst surface, the remaining NH ₃ of the denitration reaction and CO that did not react in the denitration catalyst layer are oxidized in the oxidation catalyst layer, Oxidation removal of unreacted NH ₃ and CO can be performed without reducing the denitration performance. However, even in this method, since the oxidation catalyst layer exists on the gas inflow side, it is inevitable that NH ₃ is oxidized in a temperature range where the oxidation catalyst performance of 400 ° C. or higher is remarkably high. Could not get.

As another means, a method is also proposed in which only the denitration catalyst is supported on the front stage side where the exhaust gas flows in, and the oxidation catalyst is supported on the subsequent stage side to oxidize and remove only the remaining NH ₃ of the denitration reaction. (Patent Document 3, Patent Document 4, etc.). However, in this method, since the oxidation activity of the oxidation catalyst is high in a high temperature range, if the NH ₃ / NO molar ratio is attempted to be operated at 1 or more in order to remove NOx at a high denitration rate, the remaining NH _{3 of the} denitration is in a subsequent stage. Since it is oxidized by this oxidation catalyst and produces NOx as a by-product, a high denitration rate cannot be obtained.
The object of the present invention is to have a high denitration performance and a removal performance of unreacted NH ₃ in a high temperature range of 400 to 600 ° C., so that a high denitration performance can be obtained and CO can also be removed. And a method for producing the same.

  The above problem is that the base material is a metal lath and has an oxidation catalyst layer containing a noble metal-based oxidation catalyst component on the downstream side portion of the base material surface in the exhaust gas flow direction. This is solved by an exhaust gas purifying catalyst in which a denitration catalyst component layer is formed.

  The exhaust gas-purifying catalyst is formed by applying an oxidation catalyst paste or slurry to a band-shaped region extending in the longitudinal direction of the substrate with a width less than ½ of the substrate width along one end in the width direction of the band-shaped substrate. Forming a denitration catalyst layer by carrying a denitration catalyst paste or slurry on the entire band-shaped base material on which the oxidation catalyst layer is formed, including the surface of the oxidation catalyst layer; On the strip-shaped base material after the formation of the denitration catalyst layer, ridges having ridges with an angle formed with respect to the longitudinal direction of the strip-shaped base material of greater than 0 degrees and smaller than 90 degrees are repeatedly formed at intervals, It is possible to continuously produce the catalyst element by cutting the strip-shaped base material on which the protrusions are formed, and sequentially laminating the obtained catalyst element with the front and back alternately reversed. .

  The method for supporting the oxidation catalyst component or the denitration catalyst component may be a method in which a catalyst paste is applied by roller, or a method in which the catalyst component slurry is impregnated and coated.

  The surface of the metal lath as a base material may be preliminarily coated with a surface treatment agent made of silica sol, titanium oxide, polyvinyl alcohol, or a titanium peroxide solution or a sol-like material thereof as an inactivation film. .

According to the above configuration, only the denitration catalyst component is supported on the exhaust gas inflow side (upstream portion of the gas flow direction) of the catalyst, and the oxidation catalyst component is not supported. Therefore, NOx is detoxified by N ₂ and the denitration reaction is performed. Only NH ₃ that was not used in the process moves to the gas outflow side (downstream part in the gas flow direction). On the gas outflow side, the lower layer is an oxidation catalyst layer and the upper layer is a two-layer coating of a denitration catalyst. Even if NH ₃ comes into contact with the oxidation catalyst and becomes NOx, the denitration catalyst passes through the upper layer of the oxidation catalyst layer. Since it becomes N ₂ by the reaction with NH _{3 in the} layer, it is possible to prevent the downstream from flowing out as NOx.
In the treatment of exhaust gas, the exhaust gas purification catalyst according to the present invention is installed in exhaust gas at 400 to 600 ° C. containing nitrogen oxides and carbon monoxide, and nitrogen oxides and monoxide in the exhaust gas are present in the presence of ammonia. Carbon and unreacted ammonia are removed.

  According to the present invention, a catalyst capable of obtaining high activity even at a low concentration can be obtained, and compact denitration capable of efficiently purifying NOx and CO in gas turbine exhaust gas having no HRSG and high-temperature exhaust gas such as a gas engine or diesel engine. A device can be realized.

As shown in FIG. 1, the catalyst according to the present invention carries a catalyst layer containing an oxidation catalyst component 2 only on the exhaust gas outflow portion on the surface of the metal lath substrate 1, and the metal lath substrate 1 including the upper surface of the oxidation catalyst layer 2. A catalyst layer containing the denitration catalyst component 3 is formed as a whole.
This catalyst can be obtained continuously according to the basic flow shown in FIG. That is, while the strip-shaped metal lath substrate 5 wound around the roll is unwound, a separately prepared oxidation catalyst paste 6 is pressure-bonded and supported using an application roller so as to fill the lath. At this time, the oxidation catalyst paste 6 is supported not on the entire surface of the band-shaped metal lath substrate 5 but on a band-shaped portion extending in the longitudinal direction along the end in the width direction of the band-shaped substrate 5 as shown in FIG. Next, a separately prepared denitration catalyst paste 8 is supported on the entire band-shaped substrate (hereinafter referred to as a band-shaped substrate with an oxidation catalyst) 7 on which an oxidation catalyst is supported, using an application roller. Next, a belt-like base material 7 ′ obtained by supporting the oxidation catalyst paste 6 and the denitration catalyst paste 8 (hereinafter referred to as a belt-like base material with an oxidation catalyst and a denitration catalyst) 7 ′ is used as a spacer by a hydraulic press 9. A ridge portion 10 having a corrugated and notched cross section is formed.

  What is important here is that when forming the ridge 10, as shown in FIG. 3, an inclination angle of more than 0 degree and less than 90 degrees with respect to the longitudinal direction of the strip-like base material 7 ′ with the oxidation catalyst and the denitration catalyst. A wavy ridge portion 10 having a ridge line having θ is formed. The strip-shaped catalyst on which the ridges 10 are formed is cut to obtain the catalyst element 11, and the catalyst elements 11 are sequentially stacked with the front and back alternately reversed as shown in FIG. 5, and assembled into the unit 12 as shown in FIG. . The arrows 4 in FIGS. 5 and 6 indicate the flow direction of the exhaust gas, and it is important that the stacking direction of the elements is the exhaust gas outflow side on the side where the oxidation catalyst is attached as shown in FIG. The obtained unit 12 is baked at 400 to 600 ° C.

As another method for obtaining the band-like base material 7 with the oxidation catalyst, as shown in FIG. 7, the bundle of base materials 5 is impregnated into the oxidation catalyst slurry 13 and then drained, the lath is made empty and then dried. You can also take. Further, as another method for supporting the denitration catalyst, a method in which the belt-like substrate to which the oxidation catalyst is attached is taken out after being immersed in a denitration catalyst slurry tank, drained with a roller or the like, and then dried can be used.
In addition, the base material is cut into a predetermined length in advance to obtain an element, and after supporting and drying the oxidation catalyst component 2 on one end of the element, this time the denitration catalyst component 3 is supported on the entire element, After forming the part, the method of laminating the elements, or by cutting the base material into elements in advance and forming the protrusions, assembling the unit, immersing one end of the unit in the oxidation catalyst slurry and drying, then the entire unit The catalyst shown in FIG. 1 can also be obtained by a method in which the catalyst is immersed in a denitration catalyst slurry, dried and calcined. However, in order to produce the catalyst continuously and efficiently, the above-described production method using a band-shaped substrate can produce the catalyst efficiently in a short time.

In order to prevent the oxidation catalyst from coming into direct contact with the metal lath substrate surface, an inactivation film may be provided on the substrate surface in advance. As a means for forming an inactivated film, a treatment liquid comprising polyvinyl alcohol, colloidal silica, fine titania described in JP-A-6-246176, or a peroxidation described in JP-A-2002-126536 is disclosed. When a titanium aqueous solution or a sol-like material is used as a treatment liquid, and this is coated on a metal lath substrate, it is dried and fired under appropriate conditions to be insolubilized to give good results.
As the oxidation catalyst, it is possible to use a composition in which a salt of a noble metal such as platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru) is supported on a support such as zeolite, silica, alumina, and titania. it can. The amount of noble metal supported is 0.01 to 1 wt%, preferably 0.02 to 0.5 wt%. If it is less than this, the oxidation of CO and NH ₃ cannot be carried out sufficiently, and if it is more than this, the oxidation activity is too strong and the denitration rate is lowered.
When zeolite is used as the support, the noble metal is supported in the pores of the zeolite and does not appear on the surface of the zeolite, so that the obtained noble metal-supported zeolite reacts with the metal substrate and the above-described oxidation performance is increased. Does not occur. Therefore, when noble metal-supported zeolite is used as an oxidation catalyst, there is no need to form an inactivated film on the metal substrate. Further, instead of the oxidation catalyst, a mixture of an oxidation catalyst and a denitration catalyst at an arbitrary ratio may be supported.

Since the supported area of the oxidation catalyst layer varies depending on the amount of noble metal in the oxidation catalyst layer, the CO concentration in the exhaust gas before treatment, and the NOx concentration, it cannot be generally stated, but if it is less than half the supported area of the denitration catalyst layer It is difficult to adversely affect the denitration reaction.
As the denitration catalyst, a so-called normal denitration catalyst component such as a composition selected from Ti, W, Mo, V, Ce, and Nb can be used, and in particular, Japanese Patent Application 2002 excellent in denitration performance in a high temperature range. Good results can be obtained by using the catalyst (Ti, W, Ce) described in JP-A-056240.
As shown in FIG. 1, the catalyst of the present invention has an oxidation catalyst component 2 supported on the downstream side of the surface of the metal lath substrate 1 in the exhaust gas flow direction, and the entire substrate 1 including the upper surface of the oxidation catalyst component 2 has a denitration catalyst. Component 3 is formed. When the oxidation catalyst component 2 is present in the entire region from the upstream portion to the downstream portion in the gas flow direction of the catalyst, even if the denitration catalyst component 3 is present in the upper layer, the oxidation catalyst activity of the noble metal is high in the high temperature region. Even in the area, oxidation of NH ₃ occurs and NOx is generated, resulting in a decrease in the denitration rate. In particular, if the NH ₃ / NO molar ratio is set to 1 or more to improve the denitration rate, a large amount of NH ₃ exists on the upstream side, and therefore, a reaction that is oxidized on the oxidation catalyst to become NO x proceeds.

On the other hand, in the catalyst of the present invention, since only the denitration catalyst component 3 is supported on the gas inflow side (upstream side portion in the gas flow direction) of the catalyst, NOx is detoxified by N ₂ and the denitration reaction is performed. Only NH ₃ that has not been used moves to the gas outflow side (downstream portion in the gas flow direction). On the gas outflow side, the lower layer is a two-layer coating of an oxidation catalyst layer and the upper layer is a denitration catalyst layer. Even if NH ₃ comes into contact with the oxidation catalyst and becomes NOx, it is removed while passing through the upper layer of the oxidation catalyst layer. Since it becomes N ₂ by reaction with NH ₃ in the catalyst layer, it can be prevented that it flows out as NOx in the downstream.
In addition, when manufacturing a catalyst as shown in FIG. 1, when manufacturing by the extrusion honeycomb molding method widely used as a method of manufacturing a denitration catalyst, an oxidation catalyst is extruded in advance to form a honeycomb, and a denitration catalyst slurry is added thereto. It is possible to coat the whole with two layers by the coating method. However, it is impossible to obtain a configuration in which the oxidation catalyst exists inside the honeycomb and only in the wake portion by the extrusion honeycomb molding method.

  On the other hand, in the present invention, as described above, the catalyst is manufactured according to the basic flow shown in FIG. First, the separately prepared oxidation catalyst paste 6 is supported on the band-shaped metal lath substrate 5 by using a coating roller so as to fill the lath. At this time, the oxidation catalyst paste 6 is supported not on the entire metal lath substrate but on a band-like portion extending in the longitudinal direction including the end in the width direction of the band-like metal lath substrate 5 as shown in FIG. In this way, the oxidation catalyst can be continuously supported only on one end of the catalyst element. As another method for supporting an oxidation catalyst, a band-shaped metal lath base material 5 whose surface is coated with an inactivated film is bundled and impregnated in an oxidation catalyst slurry 13 as shown in FIG. It is also possible to take a method of drying after leaving the lath open.

Next, a separately prepared denitration catalyst paste 8 is supported on the entire belt-like substrate 7 with an oxidation catalyst using an application roller. The obtained band-like base material 7 'with the oxidation catalyst and the denitration catalyst is further formed with a corrugated section and a notch-shaped protrusion section 10 which function as a spacer during lamination by a hydraulic press 9. Next, the strip-shaped substrate 7 ′ is cut to a length L of 300 to 1000 mm along a cutting line in a direction perpendicular to the longitudinal direction. The catalyst element 11 obtained by cutting is air-dried, and then assembled into the unit 12 with the front and back alternately stacked as shown in FIG. 5 and fired at 400 to 600 ° C.
What is important here is that when forming the wavy ridge portion 10, the ridge line of the ridge portion 10 exceeds 0 degree and less than 90 degrees with respect to the longitudinal direction of the belt-like substrate 7 'as shown in FIG. When forming the protrusion 10 so as to have the inclination angle θ and stacking the catalyst elements 11 obtained by cutting into the unit 12, the front and back of the catalyst elements 11 are alternately reversed and sequentially It is to laminate.

When the ridge portion 10 is formed so that the inclination angle θ is 0 degree, that is, the ridge line of the ridge portion 10 is balanced in the longitudinal direction of the strip-shaped substrate 7 ′, the ridge line of the ridge portion 10 is the oxidation catalyst component 2. It is formed parallel to the boundary between the formed region and the region where only the denitration catalyst component 3 is formed. For this reason, when the unit assembly is performed such that the oxidation catalyst is positioned downstream of the denitration catalyst with respect to the exhaust gas flow direction, the ridge line of the protrusion 10 is orthogonal to the gas flow direction, and the pressure loss becomes extremely high.
On the other hand, in an element having a ridge with an inclination angle θ of 0 ° <θ <90 °, the ridgelines of the ridge 10 cross each other as shown in FIG. Thus, the effect of improving the denitration performance by the diffusion of gas at the intersecting ridges 10 can be obtained, so that there is an advantage that high denitration performance can be obtained.
In addition, by forming an inactivation film on the surface of the metal lath substrate 1, it is possible to prevent the noble metal from moving to the lath substrate even if an oxidation catalyst is supported thereon.
As shown below, the catalyst of the Example which concerns on this invention, and the catalyst of the comparative example which is not so were created and compared.

1.33 × 10 ⁻² wt% of chloroplatinic acid (H ₂ [PtCl ₆ ] · 6H ₂ O) 1 L is added with 500 g of mordenite (CBV20 manufactured by Zeolist) and evaporated to dryness in a sand bath. By baking at 500 ° C. for 2 hours, 0.01 wt% Pt-supported mordenite was prepared. The prepared mordenite was pulverized to 150 μm or less with a hammer mill, and the obtained powder was mixed with water and silica sol (Nissan Chemical, OS sol, concentration 20 wt%) to obtain an oxidation catalyst slurry having a water content of 60 wt%.

Separately, low-temperature dry titanium oxide (G5 manufactured by Millennium, surface area 275 m ² / g) 150 kg, ammonium metatungstate ((NH ₄ ) 6 · H ₂ W ₁₂ O 40 · XH ₂ O, containing 93 wt% as WO ₃ ) 51 0.9 kg, CeO ₂ sol (manufactured by Taki Chemical Co., Nidral U-15, CeO ₂ content 15 wt%) 26.4 kg, oxalic acid 7.5 kg, silica sol (Nissan Chemical, OS sol, concentration 20 wt%) 50.6 kg Then, a paste having a water content of 35 wt% was obtained by kneading with water and a kneader, and 42.5 kg of alumina silicate inorganic fiber (manufactured by Toshiba Fiber Flux) was added thereto and kneaded again to obtain a denitration catalyst paste having a water content of 32 wt%.

  A metal lath substrate having a thickness of 0.2 mm and a 100 mm square was immersed in an oxidation catalyst slurry for 1/3 length, pulled out, drained, and air-dried. Further, a denitration catalyst paste was applied to the entire 100 mm square substrate with a roller to obtain a catalyst in which the gap between the laths was filled with the denitration catalyst. The obtained catalyst was cut into a length of 100 mm × 20 mm.

  Add 430 ml of nitric acid (containing 60%), 8.95 kg of activated alumina, 31 kg of water, and 8.95 kg of alumina silicate-based inorganic fiber to 20 kg of 0.01 wt% Pt-supported mordenite of Example 1 and knead with a kneader to prepare an oxidation catalyst paste. Obtained. The obtained paste was applied to a width of 33 mm of a metal lath substrate having a thickness of 0.2 mm, a width of 100 mm and a length of 300 mm with a roller, and the gap between the laths having a width of 33 mm was filled with an oxidation catalyst, and the remaining 67 mm was a lath substrate. After the catalyst was dried and dried, a denitration catalyst paste was applied to the entire surface of the substrate with a roller in the same manner as in Example 1 to obtain a catalyst in which the gap between the laths was filled with the denitration catalyst.

The mordenite of Example 1 is changed to fine silica powder (manufactured by Tomita Pharmaceutical Co., Ltd., microcomputer F), and treated with a treatment liquid composed of polyvinyl alcohol, colloidal silica, fine titania as described in JP-A-6-246176, and inert on the surface of the lath. A catalyst was prepared in the same manner as in Example 1 except that a chemical film was formed.
<Comparative Example 1>
A catalyst was prepared in the same manner as in Example 1 except that the oxidation catalyst slurry of Example 1 was not impregnated.
<Comparative example 2>
A catalyst was prepared in the same manner as in Example 1 except that the entire metal lath substrate was immersed in the oxidation catalyst slurry of Example 1.
<Comparative Example 3>
The denitration catalyst paste was applied to the metal lath substrate of Example 1 with a roller and then dried. Next, it was immersed in an oxidation catalyst slurry for 1/3 length, drawn, drained, dried, and calcined at 500 ° C. for 2 hours to obtain a catalyst. The obtained catalyst was cut into a length of 100 mm × 20 mm.
The catalysts of Examples 1 to 3 and Comparative Examples 1 to 3 were filled into a flow-type reaction tube, and the denitration rate, CO oxidation rate, and reaction tube outlet at 500 ° C. under gas conditions (1) and (2) shown in Table 1. The amount of NH ₃ was measured. The obtained results are shown in Table 2.

表２に示されるように、実施例１〜３の触媒は、高い脱硝率とＣＯ除去率が得られており、また出口のＮＨ_３の流出量も少ない。一方、酸化触媒のない比較例１の触媒では、ＣＯの除去活性はほとんど得られない。また比較例２〜３の触媒は実施例１〜３の触媒に比べてＣＯ除去率が高く出口のＮＨ_３流出量は少ないが、脱硝率が低い。特に条件(２)の、ＮＨ_３/ＮＯモル比が１.４の条件にすると、この傾向が顕著になり、本発明による触媒構成で、高い脱硝率とＣＯ酸化率及び少ないリークＮＨ_３を達成できることが分かる。

As shown in Table 2, the catalysts of Examples 1 to 3 have high denitration rates and CO removal rates, and the amount of NH _{3 at} the outlet is small. On the other hand, almost no CO removal activity is obtained with the catalyst of Comparative Example 1 having no oxidation catalyst. In addition, the catalysts of Comparative Examples 2 to 3 have a higher CO removal rate than the catalysts of Examples 1 to 3 and a small amount of NH ₃ outflow at the outlet, but a low NOx removal rate. In particular, when the NH ₃ / NO molar ratio in the condition (2) is 1.4, this tendency becomes remarkable. With the catalyst configuration according to the present invention, a high denitration rate, a CO oxidation rate, and a small leak NH ₃ are achieved. I understand that I can do it.

1 is a cross-sectional view showing an exhaust gas purifying catalyst according to an embodiment of the present invention. It is a conceptual diagram which shows the manufacture procedure of the catalyst for exhaust gas purification which concerns on embodiment of this invention. It is a conceptual diagram which shows a part of manufacturing procedure shown in FIG. 1 is a perspective view showing an exhaust gas purifying catalyst according to an embodiment of the present invention. It is a top view which shows the lamination | stacking state of the exhaust gas purification catalyst which concerns on embodiment of this invention. It is a perspective view which shows the lamination | stacking state of the exhaust gas purification catalyst which concerns on embodiment of this invention. It is a conceptual diagram which shows the other example of the manufacturing procedure of the catalyst for exhaust gas purification which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal lath base material 2 Oxidation catalyst component 3 Denitration catalyst component 4 Arrow which shows gas flow direction 5 Band-shaped metal lath base material 6 Oxidation catalyst paste 7 Band-shaped base material 7 'with an oxidation catalyst 8 Band-shaped base material with an oxidation catalyst and a denitration catalyst 8 Denitration catalyst Paste 9 Hydraulic press 10 Projection 11 Catalyst element 12 Unit 13 Oxidation catalyst slurry

Claims (8)

  For exhaust gas purification, exhaust gas is allowed to flow along the catalyst layer supported on the base material, and nitrogen oxide and carbon monoxide contained in the exhaust gas are reacted in the presence of ammonia to reduce their concentration. A metal lath is used as the substrate, and the catalyst layer includes an oxidation catalyst layer including a noble metal-based oxidation catalyst component supported on a downstream portion of the substrate in the exhaust gas flow direction, and the oxidation catalyst layer. A catalyst for exhaust gas purification comprising a denitration catalyst layer supported on the entire surface of the substrate including the surface.   2. The exhaust gas purifying catalyst according to claim 1, wherein the base material is formed with a ridge having a ridge line whose angle with respect to the exhaust gas flow direction is larger than 0 degree and smaller than 90 degrees. Exhaust gas purification catalyst.   3. The exhaust gas purifying catalyst according to claim 1, wherein an area of the oxidation catalyst layer is less than ½ of a surface area of the base material.   The exhaust gas purifying catalyst according to any one of claims 1 to 3, wherein the metal lath surface is coated with a surface treatment agent comprising silica sol, titanium oxide, polyvinyl alcohol, or a titanium peroxide solution or a sol-form thereof. An exhaust gas purifying catalyst characterized by. An oxidation catalyst layer is supported by supporting an oxidation catalyst paste or slurry in a band-like region extending in the longitudinal direction of the substrate with a width less than ½ of the substrate width along one end in the width direction of the belt-like substrate. The procedure to form,
A procedure for forming a denitration catalyst layer by supporting a denitration catalyst paste or slurry on the entire band-shaped base material on which the oxidation catalyst layer is formed, including the surface of the oxidation catalyst layer;
A procedure for repeatedly forming ridges having ridges with an angle greater than 0 degrees and smaller than 90 degrees with respect to the longitudinal direction of the band-shaped substrate on the band-shaped substrate after the formation of the denitration catalyst layer When,
A procedure for obtaining a catalytic element by cutting a strip-shaped base material on which a protrusion is formed;
A procedure for sequentially stacking the obtained catalyst elements by alternately reversing the front and back;
A method for producing an exhaust gas purifying catalyst comprising:   6. The method for producing an exhaust gas purifying catalyst according to claim 5, wherein the supporting method of the oxidation catalyst component or the denitration catalyst component is a method in which a catalyst paste is applied by roller or impregnated in a catalyst component slurry and coated. A method for producing an exhaust gas purifying catalyst.   7. The method for producing an exhaust gas purifying catalyst according to claim 5 or 6, wherein a metal lath is used as a belt-shaped substrate, and a silica sol, titanium oxide, polyvinyl alcohol is preliminarily formed on the surface of the metal lath before supporting the oxidation catalyst component on the surface of the metal lath. A method for producing a catalyst for exhaust gas purification, comprising a step of coating a surface treatment agent comprising: a titanium peroxide solution or a sol-form thereof.   An exhaust gas purifying catalyst is installed in exhaust gas at 400 to 600 ° C. containing nitrogen oxides and carbon monoxide, and in the presence of ammonia, nitrogen oxides and carbon monoxide in the exhaust gas are removed and unreacted ammonia An exhaust gas treatment method for removing exhaust gas, wherein the exhaust gas purification catalyst is the exhaust gas purification catalyst according to any one of claims 1 to 4.

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