Exhaust gas purification catalyst for ammonia engine

Abstract

To provide an exhaust gas purification catalyst for an ammonia engine, capable of purifying unburned ammonia (NH3) and / or nitrogen oxides (NOx) contained in exhaust gas during start-up of the ammonia engine, while suppressing emission of nitrous oxide (N2O).SOLUTION: An exhaust gas purification catalyst for an ammonia engine, comprises support particles 211 and a catalytic noble metal 212 supported on the support particles 211, wherein the support particles 211 comprise alumina support particles, and at least 90 mol% of the catalytic noble metal 212 is supported on the alumina support particles.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an exhaust gas purification catalyst for an ammonia engine. [Background technology]

[0002] An ammonia engine is an internal combustion engine that burns ammonia (NH3) to obtain driving force. Ammonia does not emit carbon dioxide (CO2) when burned, so there are high hopes for the practical application of ammonia engines. However, when an ammonia engine is running, it emits unburned ammonia and nitrogen oxides (NO x ) are emitted, and in order to purify them, the following exhaust purification devices are known.

[0003] Patent Document 1 discloses an exhaust purification device for purifying exhaust gas from an internal combustion engine fueled by ammonia, the device comprising: a catalyst having a function of reducing nitrogen oxides and a function of oxidizing ammonia; an activation state detection unit for detecting the activation state of the catalyst; a first air-fuel ratio acquisition unit for acquiring the air-fuel ratio in the exhaust gas upstream of the catalyst; and a control unit for controlling the amount of ammonia supplied by a fuel supply unit that supplies ammonia to the internal combustion engine, wherein the control unit temporarily increases the amount of ammonia supplied when the catalyst is activated and a concentration index value calculated using the air-fuel ratio acquired by the first air-fuel ratio acquisition unit, the concentration index value representing the degree of oxygen poisoning in the catalyst, exceeds a predetermined threshold. The exhaust purification device in Patent Document 1 is said to be able to quickly purify nitrogen oxides and ammonia contained in the exhaust gas from an ammonia engine.

[0004] Patent Document 2 discloses an exhaust gas purification device including an internal combustion engine fueled by at least ammonia, a catalyst disposed downstream of the internal combustion engine for oxidizing and reducing unburned ammonia and nitrogen oxides contained in the exhaust gas discharged from the internal combustion engine, an adsorber disposed downstream of the catalyst for adsorbing ammonia, and a control unit for adjusting the equivalence ratio of a mixture containing the fuel and oxygen supplied to the internal combustion engine to 1.1 or more until the catalyst reaches a predetermined temperature. According to the exhaust gas purification device of Patent Document 2, it is possible to provide an exhaust gas purification device that can suppress the emission of unburned ammonia and nitrogen oxides when starting an internal combustion engine fueled by ammonia. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-090895 [Patent Document 2] Patent Publication No. 2021-116802 Summary of the Invention [Problem to be solved by the invention]

[0006] The exhaust gas purification catalyst for ammonia engines contains unburned ammonia (NH3) and nitrogen oxides (NO x When an ammonia engine exhaust gas purification catalyst is used, these exhaust gases are purified into nitrogen (N2) and water (H2O). However, when purifying exhaust gases using an ammonia engine exhaust gas purification catalyst, there is a problem in that nitrous oxide (N2O), a known greenhouse gas, is generated and emitted. This problem is of particular concern when starting an ammonia engine.

[0007] The carrier particles of the exhaust gas purification catalyst for ammonia engines are made of ceramics, titanium oxide, etc., and are not designed specifically for exhaust gas purification catalysts for ammonia engines, as in Patent Document 1 and Patent Document 2. Therefore, there is room for improvement in the performance of the exhaust gas purification catalyst for ammonia engines from the viewpoint of the carrier particles.

[0008] Therefore, the present invention aims to reduce the amount of unburned ammonia (NH3) and / or nitrogen oxides (NO2) in the exhaust gas when starting an ammonia engine. x The present invention aims to provide an exhaust gas purification catalyst for an ammonia engine that can purify nitrous oxide (NO) and suppress the emission of dinitrogen monoxide (N2O). [Means for solving the problem]

[0009] The present invention achieves the above object by the following means.

[0010] <Aspect 1> The catalyst includes support particles and a catalytic noble metal supported on the support particles, the support particles comprise alumina support particles; and 90 mol % or more of the catalytic noble metal is supported on the alumina support particles. Exhaust gas purification catalyst for ammonia engines. <Aspect 2> 2. The exhaust gas purification catalyst for an ammonia engine according to aspect 1, wherein the catalytic noble metal is at least one noble metal selected from the group consisting of rhodium, palladium, and platinum. <Aspect 3> Aspect 3. The exhaust gas purification catalyst for an ammonia engine according to aspect 1 or 2, wherein the support particles further comprise support particles selected from zirconia support particles, ceria support particles, and combinations thereof. <Aspect 4> a substrate and a catalyst layer on the substrate; The catalyst layer comprises the exhaust gas purification catalyst for an ammonia engine according to any one of aspects 1 to 3. Exhaust gas purification catalyst device for ammonia engines. <Aspect 5> A method for purifying exhaust gas, comprising purifying exhaust gas emitted from an ammonia engine by bringing the exhaust gas into contact with the catalyst for exhaust gas purification for an ammonia engine according to any one of aspects 1 to 3. [Effects of the Invention]

[0011] According to the exhaust gas purification catalyst for an ammonia engine of the present invention, when the ammonia engine is started, unburned ammonia (NH3) and / or nitrogen oxides (NO x ) can be purified and N2O emissions can be suppressed. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram for explaining the exhaust gas purification catalyst for an ammonia engine of the present invention. [Figure 2] FIG. 2 is a schematic diagram for explaining the exhaust gas purification catalyst device for an ammonia engine of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described in detail. Note that the present invention is not limited to the following embodiment, and various modifications can be made within the scope of the gist of the present invention. In addition, in the description of the drawings, the same elements are given the same reference numerals, and duplicated explanations will be omitted.

[0014] <Exhaust gas purification catalyst for ammonia engines> The exhaust gas purification catalyst for an ammonia engine of the present invention comprises: The catalyst includes support particles and a catalytic noble metal supported on the support particles, the support particles comprise alumina support particles; and 90 mol % or more of the catalytic noble metal is supported on the alumina support particles. Exhaust gas purification catalyst for ammonia engines.

[0015] According to the exhaust gas purification catalyst for an ammonia engine of the present invention, when the ammonia engine is started, unburned ammonia (NH3) and / or nitrogen oxides (NO x ) can be purified and N2O emissions can be suppressed.

[0016] The inventors carried catalytic precious metals on various carrier particles and investigated temperature characteristic tests simulating the start-up of an ammonia engine. As a result, by carrying catalytic precious metals on alumina carrier particles, the amount of unburned NH3 and / or NO in the exhaust gas was reduced in the temperature characteristic tests. x It was found that this method can purify NO and suppress N2O emissions.

[0017] Without being limited by theory, it is believed that the use of alumina support particles, compared to support particles such as ceria support particles and zirconia support particles, promotes the activation of catalytic noble metals and promotes the production of nitrogen (N), which is the main product of the NH purification reaction, thereby reducing the amount of unburned NH and / or NO as exhaust gases when the ammonia engine is started. x It is predicted that this will enable the purification of NO and suppress NO emissions. On the other hand, for example, when catalytic precious metals are supported on support particles that have oxygen storage capacity, such as ceria-zirconia support particles, nitrogen atoms and oxygen atoms tend to bond more easily, which is predicted to increase the generation of NO.

[0018] In the present invention, an "ammonia engine" may be an internal combustion engine that burns at least ammonia, and therefore may be an internal combustion engine that burns (co-firing) ammonia together with a hydrocarbon fuel such as diesel or gasoline, or an internal combustion engine that burns only ammonia. Here, when the "ammonia engine" is an internal combustion engine that co-firing a hydrocarbon fuel together with ammonia, the ammonia co-firing ratio (the mixing ratio of ammonia based on combustion energy) may be 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more, or may be less than 100%, 95% or less, 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less.

[0019] FIG. 1 is a schematic diagram showing one embodiment of the exhaust gas purification catalyst for an ammonia engine of the present invention, but the present invention is not limited to this.

[0020] The exhaust gas purification catalyst 210 for an ammonia engine has support particles 211 and catalytic noble metal 212 supported on the support particles 211. In the present invention, the proportion of the catalytic noble metal 212 supported on the alumina support particles is 90 mol % or more. By supporting the catalytic noble metal 212 on the alumina support particles, activation of the catalytic noble metal 212 is promoted compared to when the catalytic noble metal 212 is supported on support particles such as ceria support particles or zirconia support particles, and the catalytic noble metal 212 is more efficiently activated, and the catalytic noble metal 212 is more efficiently purified. x ) can be purified and N2O emissions can be suppressed.

[0021] <Catalytic precious metals> In the exhaust gas purification catalyst for an ammonia engine of the present invention, the catalytic noble metal is not particularly limited, but can be appropriately selected from those that promote the ammonia purification reaction. The catalytic noble metal is not particularly limited, but is preferably at least one noble metal selected from rhodium, palladium, and platinum.

[0022] The particle size of the catalytic noble metal (primary particles) may be, for example, 1 nm or more, 5 nm or more, 10 nm or more, 15 nm or more, 20 nm or more, or 30 nm or more, or 100 nm or less, 80 nm or less, or 60 nm or less. The particle size of the catalytic noble metal can be determined from the number average particle size in an image taken with a transmission electron microscope.

[0023] The catalytic noble metal may be supported in an amount of 0.1 mass% or more, 0.2 mass% or more, 0.3 mass% or more, 0.5 mass% or more, or 1.0 mass% or more, or 10 mass% or less, 8 mass% or less, 6 mass% or less, or 4 mass% or less, based on the support particles.

[0024] <Support particles - alumina support particles> In the exhaust gas purification catalyst for an ammonia engine of the present invention, the support particles include alumina support particles.

[0025] In the present invention, 90 mol% or more of the catalytic noble metal is supported on the alumina support particles. This proportion is not particularly limited, but may be 90 mol% or more, 95 mol% or more, 97 mol% or more, 98 mol% or more, or 99 mol% or more, or may be 100 mol% or less. The proportion of the catalytic noble metal supported on the alumina support particles can be determined by confirming 200 or more particles, for example, approximately 200 to 300 particles, using transmission electron microscope-energy dispersive X-ray analysis (TEM-EDX).

[0026] In the exhaust gas purification catalyst for an ammonia engine, the content of the alumina support particles is not particularly limited, but may be 10 mass% or more, 20 mass% or more, 30 mass% or more, 40 mass% or more, or 50 mass% or more, or may be 100 mass% or less, 90 mass% or less, 80 mass% or less, 70 mass% or less, or 60 mass% or less, based on 100 mass% of the exhaust gas purification catalyst for an ammonia engine.

[0027] The particle size of the alumina support particles (secondary particles) may be, for example, 2 μm or more, 3 μm or more, or 4 μm or more, or 80 μm or less, 50 μm or less, 30 μm or less, 20 μm or less, or 10 μm or less. The particle size of the support particles can be determined as the median size obtained by dynamic light scattering of a suspension in which the alumina support particles are dispersed in an appropriate liquid medium (e.g., water).

[0028] Specifically, the catalytic noble metal can be supported on the alumina support particles by, for example, contacting the alumina support particles with a catalytic noble metal precursor in a suitable liquid medium, preferably water, and then drying and calcining the recovered solid content. As the catalytic noble metal precursor, nitrates, sulfates, hydrochlorides, acetates, etc. of the desired catalytic noble metal can be used.

[0029] <Support particles - Support particles other than alumina support particles> In the exhaust gas purification catalyst for an ammonia engine of the present invention, the support particles are not particularly limited, but the support particles may further include support particles selected from zirconia support particles, ceria support particles, and combinations thereof.

[0030] As described above, in the present invention, 90 mol % or more of the catalytic noble metal is supported on the alumina support particles. Therefore, the support particles selected from the group consisting of zirconia support particles, ceria support particles, and combinations thereof are not particularly limited, and may not support the catalytic noble metal.

[0031] In the exhaust gas purification catalyst for an ammonia engine, the content of the support particles selected from zirconia support particles, ceria support particles, and a combination thereof is not particularly limited, but may be 10 mass% or more, 20 mass% or more, 30 mass% or more, 40 mass% or more, or 50 mass% or more, or may be 80 mass% or less, 70 mass% or less, or 60 mass% or less, based on 100 mass% of the exhaust gas purification catalyst for an ammonia engine.

[0032] The particle size of the support particles (secondary particles) selected from zirconia support particles, ceria support particles, and combinations thereof may be, for example, 2 μm or more, 3 μm or more, or 4 μm or more, or 80 μm or less, 50 μm or less, 30 μm or less, 20 μm or less, or 10 μm or less. The particle size of the support particles can be determined as the median size obtained by dynamic light scattering of a suspension in which the support particles are dispersed in an appropriate liquid medium (e.g., water).

[0033] The exhaust gas purification catalyst for an ammonia engine is not particularly limited, but support particles on which a catalytic noble metal is supported may be used as the exhaust gas purification catalyst for an ammonia engine, or a mixture of support particles on which a catalytic noble metal is supported and other support particles in a wet or dry manner may be used as the exhaust gas purification catalyst for an ammonia engine.

[0034] <Exhaust gas purification catalyst device for ammonia engine> The exhaust gas purification catalyst device for an ammonia engine of the present invention comprises: a substrate and a catalyst layer on the substrate; The catalyst layer contains the above-mentioned exhaust gas purification catalyst for an ammonia engine.

[0035] According to the exhaust gas purification catalyst device for an ammonia engine of the present invention, when the ammonia engine is started, unburned ammonia (NH3) and / or nitrogen oxides (NO x ) can be purified and N2O emissions can be suppressed.

[0036] FIG. 2 is a schematic diagram showing one embodiment of the catalytic device for purifying exhaust gas for an ammonia engine according to the present invention, but the present invention is not limited to this.

[0037] The catalytic device 10 for purifying exhaust gas for an ammonia engine includes a substrate 100 and a catalyst layer 200 on the substrate 100. The catalyst layer 200 includes the above-mentioned catalyst for purifying exhaust gas for an ammonia engine of the present invention, and may include a binder as needed. By including the catalyst layer 200 in the catalyst for purifying exhaust gas for an ammonia engine of the present invention, unburned ammonia (NH3) and / or nitrogen oxides (NO x ) can be purified and N2O emissions can be suppressed.

[0038] <Base material> The substrate may have a planar shape or a honeycomb shape having a plurality of gas flow paths separated by partition walls. The substrate may be made of a ceramic or metal substrate. Examples of ceramic substrates include, but are not limited to, cordierite (2MgO-2Al2O3-5SiO2), silicon carbide (SiC), alumina (Al2O3), mullite (3Al2O3-2SiO2), and aluminum titanate (Al2TiO5). Examples of metal substrates include, but are not limited to, stainless steel (SUS), Fe-Cr-Al alloys, and Ni-Cr-Al alloys.

[0039] <Catalyst layer> The catalyst layer contains the above-mentioned catalyst for purifying exhaust gas for an ammonia engine, and may contain a binder as necessary. For the catalyst for purifying exhaust gas for an ammonia engine, please refer to the above description of "Catalyst for purifying exhaust gas for an ammonia engine".

[0040] (binder) The binder is not particularly limited, but an inorganic binder can be used, etc. Examples of inorganic binders include alumina (Al2O3), titania (TiO2), zirconia (ZrO2), etc., but are not limited to this.

[0041] Specifically, the formation of the catalyst layer may include, for example, preparing a slurry containing the exhaust gas purification catalyst for an ammonia engine, coating the slurry on a substrate, and optionally firing the coating.

[0042] In forming the catalyst layer, the amount of coating on the substrate is not particularly limited, but may be 20 g / L or more, 40 g / L or more, 80 g / L or more, or 120 g / L or more, or may be 400 g / L or less, 350 g / L or less, 300 g / L or less, 250 g / L or less, or 200 g / L or less, relative to the volume of the substrate.

[0043] The amount of catalytic noble metal in the catalyst layer, in terms of metal equivalent mass per 1 L of substrate volume, may be 0.1 g / L or more, 0.2 g / L or more, 0.3 g / L or more, 0.4 g / L or more, or 0.5 g / L or more, and may be 8.00 g / L or less, 6.00 g / L or less, 4.00 g / L or less, 3.00 g / L or less, or 2.00 g / L or less.

[0044] <Exhaust gas purification method> The exhaust gas purification method of the present invention comprises: The method includes purifying exhaust gas emitted from an ammonia engine by bringing the exhaust gas into contact with the above-mentioned exhaust gas purification catalyst for an ammonia engine.

[0045] According to the exhaust gas purification method of the present invention, unburned ammonia (NH3) and / or nitrogen oxides (NO x ) can be purified and N2O emissions can be suppressed.

[0046] The exhaust gas emitted from an ammonia engine is not particularly limited, but may include unburned fuel residue and harmful substances such as unburned ammonia (NH3) and nitrogen oxides (NO x ) etc.

[0047] The method for contacting the exhaust gas is not particularly limited, and the exhaust gas may be contacted by flowing through the catalyst for exhaust gas purification for an ammonia engine, or may be contacted by flowing through a catalyst device for exhaust gas purification for an ammonia engine including the catalyst for exhaust gas purification for an ammonia engine.

[0048] The temperature at which the exhaust gas is purified is not particularly limited, but may be 100°C or higher, 200°C or higher, or 300°C or higher, or 900°C or lower, 800°C or lower, or 700°C or lower.

[0049] The exhaust gas purification method can be used for any application, for example, but not limited to, an internal combustion engine, a fuel cell, or an ammonia burner. [Example]

[0050] The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to these examples.

[0051] Example 1 <Production of exhaust gas purification catalyst A1 for ammonia engine> Alumina support particles (Al2O3 support particles) were added to an aqueous solution containing rhodium nitrate as a catalytic precious metal precursor and mixed. The rhodium content was adjusted to 0.25 wt% relative to the Al2O3 support particles. The mixture was then dried and calcined, reducing the rhodium nitrate as a catalytic precious metal precursor to rhodium as a catalytic precious metal, and supporting the rhodium on the Al2O3 support particles. Thus, rhodium-supported Al2O3 support particles (Rh / Al2O3 support particles) were prepared. The Rh / Al2O3 support particles (40 parts by mass) were then mixed with ceria-zirconia support particles (CZ support particles) (40 parts by mass) to prepare an exhaust gas purification catalyst A1 for an ammonia engine. The proportion of rhodium supported on the Al2O3 support particles in the exhaust gas purification catalyst A1 for an ammonia engine was 90 mol% or more. Furthermore, the content of the Rh / Al2O3 support particles was 50 mass % and the content of the CZ support particles was 50 mass % relative to the total amount of the ammonia engine exhaust gas purification catalyst A1.

[0052] <Preparation of catalyst layer B1> Ammonia engine exhaust gas purification catalyst A1 (80 parts by mass) and an alumina-based binder (2 parts by mass) were mixed and suspended in a solvent to prepare a slurry containing the ammonia engine exhaust gas purification catalyst A1. This slurry was poured into a cordierite honeycomb substrate (φ30 mm × 50 mm) as a substrate, and unnecessary portions were blown off with a blower to form a coating film of the slurry containing the ammonia engine exhaust gas purification catalyst A1 on the substrate wall surface. Next, this coating film was dried and fired in an electric furnace to produce a catalyst layer B1. Here, the coating amount of the catalyst layer B1 on the substrate was adjusted to be 82 g / L.

[0053] <Temperature characteristic test of exhaust gas purification catalyst A1 for ammonia engine> For the exhaust gas from an ammonia engine, an ammonia-containing mixed gas with the composition shown in Table 1 was used as a model gas. To test the temperature characteristics of the catalyst A1 for exhaust gas purification for an ammonia engine, a catalyst layer B1 containing the catalyst A1 for exhaust gas purification for an ammonia engine was placed in a thermostatic chamber where the catalyst layer B1 reacted with the ammonia-containing mixed gas. The catalyst layer B1 was heated to 500°C, and then 1% hydrogen gas was passed through it for 5 minutes. The catalyst layer B1 was then cooled to 100°C or below. Next, the catalyst layer B1 was heated from 100°C to 500°C at a rate of 20°C / min while the ammonia-containing mixed gas was passed through it, causing the catalyst A1 for exhaust gas purification for an ammonia engine contained in the catalyst layer B1 to react with the ammonia-containing mixed gas. The temperature characteristics of the catalyst A1 for exhaust gas purification for an ammonia engine were evaluated by detecting the purified gas. Specifically, the temperature at which the ammonia (NH3) concentration in the purified gas was halved was analyzed as the temperature at which the NH3 concentration in the introduced ammonia-containing mixed gas reached half its original concentration. In addition, the concentration of nitrous oxide (N2O) emitted during measurement was integrated to determine the amount of N2O emitted from the purified gas (sampling was performed every 0.5 seconds). For the ammonia engine exhaust gas purification catalyst A1, the temperature at which the NH3 concentration was reduced by half was 314.5°C, and the integrated value of the N2O emission concentration was 18,915 ppm.

[0054] [Table 1]

[0055] Example 1-1 <Preparation of exhaust gas purification catalyst A1-1 for ammonia engine> Alumina support particles (Al2O3 support particles) were added to and mixed with an aqueous solution containing rhodium nitrate as a catalytic precious metal precursor. The rhodium was supported on the Al2O3 support particles at a ratio of 0.25 wt%. This mixture was then dried and calcined to reduce the rhodium nitrate as the catalytic precious metal precursor to rhodium as the catalytic precious metal. The rhodium was supported on the Al2O3 support particles, producing Rh / Al2O3 support particles. The resulting Rh / Al2O3 support particles were designated as catalyst A1-1 for exhaust gas purification for ammonia engines. The proportion of rhodium supported on the Al2O3 support particles in the ammonia engine exhaust gas purification catalyst A1-1 was 90 mol% or more. The content of the Rh / Al2O3 support particles was 100 mass% of the total amount of catalyst A1-1 for exhaust gas purification for ammonia engines.

[0056] <Preparation of catalyst layer B1-1> Ammonia engine exhaust gas purification catalyst A1-1 (40 parts by mass) and an alumina-based binder (1 part by mass) were mixed and suspended in a solvent to prepare a slurry containing the ammonia engine exhaust gas purification catalyst A1-1. This slurry was poured into a cordierite honeycomb substrate (φ30 mm × 50 mm) as a substrate, and unnecessary portions were blown off with a blower to form a coating film of the slurry containing the ammonia engine exhaust gas purification catalyst A1-1 on the substrate wall surface. Next, this coating film was dried and fired in an electric furnace to produce a catalyst layer B1-1. Here, the coating amount of the catalyst layer B1-1 on the substrate was adjusted to be 41 g / L.

[0057] <Temperature characteristic test of exhaust gas purification catalyst A1-1 for ammonia engine> The temperature characteristic test of the catalyst A1-1 for purifying exhaust gas for an ammonia engine was carried out in the same manner as in Example 1. The evaluation results of the catalyst A1-1 for purifying exhaust gas for an ammonia engine are shown in Table 2.

[0058] Example 2 <Preparation of exhaust gas purification catalyst A2 for ammonia engine> An exhaust gas purification catalyst A2 for an ammonia engine was produced in the same manner as in Example 1, except that zirconia support particles (ZrO2 support particles) were used instead of CZ support particles. The proportion of rhodium contained in the exhaust gas purification catalyst A2 for an ammonia engine that was supported on Al2O3 support particles was 90 mol% or more. Furthermore, with respect to the total amount of the exhaust gas purification catalyst A2 for an ammonia engine, the content of Rh / Al2O3 support particles was 50 mass%, and the content of ZrO2 support particles was 50 mass%.

[0059] <Preparation of catalyst layer B2 and temperature characteristic test of exhaust gas purification catalyst A2 for ammonia engine> Except for using the catalyst A2 for exhaust gas purification for an ammonia engine instead of the catalyst A1 for exhaust gas purification for an ammonia engine, a catalyst layer B2 for exhaust gas purification for an ammonia engine was produced in the same manner as in Example 1. Furthermore, a temperature characteristic test of the catalyst A2 for exhaust gas purification for an ammonia engine was carried out in the same manner as in Example 1. The evaluation results of the catalyst A2 for exhaust gas purification for an ammonia engine are shown in Table 2.

[0060] Comparative Example 1 <Production of exhaust gas purification catalyst a1 for ammonia engine> CZ support particles as support particles were introduced into an aqueous solution in which rhodium nitrate as a catalytic precious metal precursor was dissolved, and mixed. The mixture was adjusted so that rhodium was supported on the CZ support particles at 0.25 wt%. The mixture was then dried and calcined, thereby reducing the rhodium nitrate as a catalytic precious metal precursor to rhodium as a catalytic precious metal, and supporting the rhodium on the CZ support particles. Thus, CZ support particles supporting rhodium (Rh / CZ support particles) were prepared. Then, the Rh / CZ support particles (40 parts by mass) were mixed with Al2O3 support particles (40 parts by mass) to prepare an exhaust gas purification catalyst a1 for an ammonia engine. The proportion of rhodium supported on the Al2O3 support particles in the exhaust gas purification catalyst a1 for an ammonia engine was less than 90 mol%. Moreover, the content of the Rh / CZ support particles was 50 mass % and the content of the Al2O3 support particles was 50 mass % relative to the total amount of the ammonia engine exhaust gas purification catalyst a1.

[0061] <Preparation of catalyst layer b1 and temperature characteristic test of exhaust gas purification catalyst a1 for ammonia engine> A catalyst layer b1 was produced in the same manner as in Example 1, except that the catalyst a1 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1 for purifying exhaust gas for an ammonia engine. A temperature characteristic test of the catalyst a1 for purifying exhaust gas for an ammonia engine was also carried out in the same manner as in Example 1. The evaluation results of the catalyst a1 for purifying exhaust gas for an ammonia engine are shown in Table 2.

[0062] Comparative Example 1-1 <Preparation of exhaust gas purification catalyst a1-1 for ammonia engine> CZ support particles were added to and mixed with an aqueous solution containing rhodium nitrate as a catalytic precious metal precursor. The rhodium content was adjusted to 0.25 wt% relative to the CZ support particles. The mixture was then dried and calcined to reduce the rhodium nitrate as a catalytic precious metal precursor to rhodium as a catalytic precious metal, and the rhodium was supported on the CZ support particles to produce Rh / CZ support particles. The resulting Rh / CZ support particles were designated as catalyst a1-1 for exhaust gas purification for ammonia engines. The proportion of rhodium supported on the Al2O3 support particles in the catalyst a1-1 for exhaust gas purification for ammonia engines was less than 90 mol%. The content of the Rh / CZ support particles relative to the total amount of catalyst a1-1 for exhaust gas purification for ammonia engines was 100 mass%.

[0063] <Preparation of catalyst layer b1-1> A catalyst layer b1-1 was produced in the same manner as in Example 1-1, except that the catalyst a1-1 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1-1 for purifying exhaust gas for an ammonia engine.

[0064] <Temperature characteristic test of a1-1 exhaust gas purification catalyst for ammonia engine> A temperature characteristic test was carried out on the catalyst a1-1 for purifying exhaust gas for an ammonia engine in the same manner as in Example 1. The evaluation results of the catalyst a1-1 for purifying exhaust gas for an ammonia engine are shown in Table 2.

[0065] Comparative Example 2 <Production of exhaust gas purification catalyst a2 for ammonia engine> Except for using zirconia support particles (ZrO2 support particles) instead of CZ support particles, an exhaust gas purification catalyst a2 for an ammonia engine was produced in the same manner as in Comparative Example 1. The proportion of rhodium contained in the exhaust gas purification catalyst a2 for an ammonia engine that was supported on Al2O3 support particles was less than 90 mol%. Furthermore, with respect to the total amount of the exhaust gas purification catalyst a2 for an ammonia engine, the content of Rh / ZrO2 support particles was 50 mass% and the content of Al2O3 support particles was 50 mass%.

[0066] <Preparation of catalyst layer b2 and temperature characteristic test of exhaust gas purification catalyst a2 for ammonia engine> A catalyst layer b2 was produced in the same manner as in Example 1, except that the catalyst a2 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1 for purifying exhaust gas for an ammonia engine. A temperature characteristic test of the catalyst a2 for purifying exhaust gas for an ammonia engine was also carried out in the same manner as in Example 1. The evaluation results of the catalyst a2 for purifying exhaust gas for an ammonia engine are shown in Table 2.

[0067] Comparative Example 2-1 <Preparation of exhaust gas purification catalyst a2-1 for ammonia engine> ZrO2 support particles as support particles were added to an aqueous solution containing rhodium nitrate as a catalytic precious metal precursor and mixed. The rhodium was supported on the ZrO2 support particles at a ratio of 0.25 wt%. The mixture was then dried and calcined, thereby reducing the rhodium nitrate as a catalytic precious metal precursor to rhodium as a catalytic precious metal, and supporting the rhodium on the ZrO2 support particles to produce Rh / ZrO2 support particles. The resulting Rh / ZrO2 support particles were designated as ammonia engine exhaust gas purification catalyst a2-1. The proportion of rhodium supported on Al2O3 support particles in the ammonia engine exhaust gas purification catalyst a2-1 was less than 90 mol%. The content of Rh / ZrO2 support particles was 100 mass% of the total amount of ammonia engine exhaust gas purification catalyst a2-1.

[0068] <Preparation of catalyst layer b2-1> A catalyst layer b2-1 was produced in the same manner as in Example 1-1, except that the catalyst a2-1 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1-1 for purifying exhaust gas for an ammonia engine.

[0069] <Temperature characteristic test of a2-1 exhaust gas purification catalyst for ammonia engine> The temperature characteristic test of the catalyst a2-1 for purifying exhaust gas for an ammonia engine was carried out in the same manner as in Example 1. The evaluation results of the catalyst a2-1 for purifying exhaust gas for an ammonia engine are shown in Table 2.

[0070] [Table 2]

[0071] First, an exhaust gas purification catalyst for an ammonia engine, in which rhodium as a catalytic noble metal is supported on carrier particles, was investigated.

[0072] The exhaust gas purification catalysts A1-1, a1-1, and a2-1 for ammonia engines in Example 1-1 and Comparative Examples 1-1 and 2-1 are catalysts that do not contain other support particles, i.e., catalysts with a catalytic noble metal / support particle content of 100 mass%. The exhaust gas purification catalyst A1-1 for ammonia engines, in which the proportion of rhodium as the catalytic noble metal supported on Al2O3 support particles is 90 mol%, had a lower temperature at which the NH3 concentration was halved and a lower integrated value of the NO emission concentration, compared to the exhaust gas purification catalysts a1-1 and a2-1 for ammonia engines in which rhodium as the catalytic noble metal was not supported on Al2O3 support particles.

[0073] The exhaust gas purification catalysts A1, A2, a1, and a2 for ammonia engines in Examples 1 and 2 and Comparative Examples 1 and 2 are catalysts containing other support particles that do not support a catalytic precious metal. The exhaust gas purification catalysts A1 and A2 for ammonia engines, in which the proportion of rhodium as the catalytic precious metal that is supported on Al2O3 support particles is 90 mol%, had a lower temperature at which the NH3 concentration was halved and a lower integrated value of NO emission concentration, compared to the exhaust gas purification catalysts a1 and a2 for ammonia engines in which rhodium as the catalytic precious metal is not supported on Al2O3 support particles, and exhibited behavior similar to that of the catalysts that do not contain the above-mentioned other support particles.

[0074] Comparing Examples 1, 2 and 1-1, the catalysts A1 and A2 for purifying exhaust gas for an ammonia engine containing other carrier particles had a lower temperature at which the NH concentration was reduced to half and a lower integrated value of the NO emission concentration than the catalyst A1-1 for purifying exhaust gas for an ammonia engine containing no other carrier particles.

[0075] Compared to CZ and ZrO2 support particles, supporting catalytic precious metals on Al2O3 support particles promotes catalytic precious metal activation and promotes the production of nitrogen (N2), the main product of the NH3 purification reaction. This is thought to lower the temperature at which the NH3 concentration is halved and suppress NO emissions. On the other hand, when catalytic precious metals are supported on support particles with oxygen storage capacity, such as CZ support particles, it is thought that nitrogen atoms and oxygen atoms are more likely to bond, resulting in increased NO generation. From the above, it is expected that an ammonia exhaust gas purification catalyst in which the catalytic precious metal rhodium is supported on Al2O3 support particles can purify unburned NH3 in exhaust gases during engine start-up and suppress NO emissions.

[0076] Example 3 <Production of exhaust gas purification catalyst A3 for ammonia engine> Al2O3 support particles as support particles were added to an aqueous solution in which palladium nitrate as a catalytic precious metal precursor was dissolved, and mixed. Here, the mixture was adjusted so that palladium was supported on the Al2O3 support particles at 2.5 wt%. Next, this mixed solution was dried and calcined, thereby reducing the palladium nitrate as a catalytic precious metal precursor to palladium as a catalytic precious metal, and the palladium was supported on the Al2O3 support particles. In this way, Al2O3 support particles supported with palladium (Pd / Al2O3 support particles) were prepared. Thereafter, Pd / Al2O3 support particles (40 parts by mass) and CZ support particles (40 parts by mass) were mixed to prepare exhaust gas purification catalyst A3 for ammonia engines. The proportion of palladium contained in exhaust gas purification catalyst A3 for ammonia engines supported on the Al2O3 support particles was 90 mol% or more. Furthermore, the content of Pd / Al2O3 support particles was 50 mass % and the content of CZ support particles was 50 mass % relative to the total amount of the ammonia engine exhaust gas purification catalyst A3.

[0077] <Preparation of catalyst layer B3 and temperature characteristic test of exhaust gas purification catalyst A3 for ammonia engine> A catalyst layer B3 was produced in the same manner as in Example 1, except that the catalyst A3 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1 for purifying exhaust gas for an ammonia engine. A temperature characteristic test of the catalyst A3 for purifying exhaust gas for an ammonia engine was also carried out in the same manner as in Example 1. Furthermore, in the temperature characteristic test, the x ) As an index for comparing NO emissions, x The concentration of these compounds in the exhaust gas was measured by FT-IR. The evaluation results of the ammonia engine exhaust gas purification catalyst A3 are shown in Table 3.

[0078] Example 3-1 <Preparation of exhaust gas purification catalyst A3-1 for ammonia engine> Al2O3 support particles were added to an aqueous solution containing palladium nitrate as a catalytic precious metal precursor and mixed. Palladium was supported on the Al2O3 support particles at a ratio of 2.5 wt%. This mixture was then dried and calcined to reduce the palladium nitrate as a catalytic precious metal precursor to palladium as a catalytic precious metal, and the palladium was supported on the Al2O3 support particles, producing Pd / Al2O3 support particles. The resulting Pd / Al2O3 support particles were designated as catalyst A3-1 for exhaust gas purification for ammonia engines. The proportion of palladium supported on the Al2O3 support particles in the catalyst A3-1 for exhaust gas purification for ammonia engines was 90 mol% or more. The content of Pd / Al2O3 support particles was 100 mass% of the total amount of catalyst A3-1 for exhaust gas purification for ammonia engines.

[0079] <Preparation of catalyst layer B3-1> A catalyst layer B3-1 was produced in the same manner as in Example 1-1, except that the catalyst A3-1 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1-1 for purifying exhaust gas for an ammonia engine.

[0080] <Temperature characteristic test of exhaust gas purification catalyst A3-1 for ammonia engine> The temperature characteristic test of the catalyst A3-1 for purifying exhaust gas for an ammonia engine was carried out in the same manner as in Example 3. The evaluation results of the catalyst A3-1 for purifying exhaust gas for an ammonia engine are shown in Table 3.

[0081] Example 4 <Production of exhaust gas purification catalyst A4 for ammonia engine> Except for using ZrO2 support particles instead of CZ support particles, an exhaust gas purification catalyst A4 for an ammonia engine was produced in the same manner as in Example 3. The proportion of palladium contained in the exhaust gas purification catalyst A4 for an ammonia engine that was supported on Al2O3 support particles was 90 mol% or more. Furthermore, with respect to the total amount of the exhaust gas purification catalyst A4 for an ammonia engine, the content of Pd / Al2O3 support particles was 50 mass%, and the content of ZrO2 support particles was 50 mass%.

[0082] <Preparation of catalyst layer B4 and temperature characteristic test of exhaust gas purification catalyst A4 for ammonia engine> A catalyst layer B4 was produced in the same manner as in Example 1, except that the catalyst A4 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1 for purifying exhaust gas for an ammonia engine. A temperature characteristic test of the catalyst A4 for purifying exhaust gas for an ammonia engine was also carried out in the same manner as in Example 3. The evaluation results of the catalyst A4 for purifying exhaust gas for an ammonia engine are shown in Table 3.

[0083] Comparative Example 3 <Production of exhaust gas purification catalyst a3 for ammonia engine> CZ support particles as support particles were added to an aqueous solution in which palladium nitrate as a catalytic precious metal precursor was dissolved, and mixed. The mixture was adjusted so that palladium was supported on the CZ support particles at 2.5 wt%. This mixture was then dried and calcined, thereby reducing the palladium nitrate as a catalytic precious metal precursor to palladium as a catalytic precious metal, and supporting the palladium on the CZ support particles. In this way, CZ support particles supporting palladium (Pd / CZ support particles) were prepared. Then, Pd / CZ support particles (40 parts by mass) and Al2O3 support particles (40 parts by mass) were mixed to prepare an exhaust gas purification catalyst a3 for an ammonia engine. The proportion of palladium supported on the Al2O3 support particles in the exhaust gas purification catalyst a3 for an ammonia engine was less than 90 mol%. Moreover, the content of the Pd / CZ support particles was 50 mass % and the content of the Al2O3 support particles was 50 mass % relative to the total amount of the ammonia engine exhaust gas purification catalyst a3.

[0084] <Preparation of catalyst layer b3 and temperature characteristic test of exhaust gas purification catalyst a3 for ammonia engine> A catalyst layer b3 was produced in the same manner as in Example 1, except that the catalyst a3 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1 for purifying exhaust gas for an ammonia engine. A temperature characteristic test of the catalyst a3 for purifying exhaust gas for an ammonia engine was also carried out in the same manner as in Example 3. The evaluation results of the catalyst a3 for purifying exhaust gas for an ammonia engine are shown in Table 3.

[0085] Comparative Example 3-1 <Preparation of exhaust gas purification catalyst a3-1 for ammonia engine> CZ support particles were added to an aqueous solution containing palladium nitrate as a catalytic precious metal precursor and mixed. The mixture was adjusted so that 2.5 wt% of palladium was supported on the CZ support particles. This mixture was then dried and calcined, reducing the palladium nitrate as a catalytic precious metal precursor to palladium as a catalytic precious metal, and supporting the palladium on the CZ support particles to produce Pd / CZ support particles. The resulting Pd / CZ support particles were designated as catalyst a3-1 for exhaust gas purification for ammonia engines. The proportion of palladium supported on Al2O3 support particles in the catalyst a3-1 for exhaust gas purification for ammonia engines was less than 90 mol%. The content of Pd / CZ support particles was 100 mass% of the total amount of catalyst a3-1 for exhaust gas purification for ammonia engines.

[0086] <Preparation of catalyst layer b3-1> A catalyst layer b3-1 was produced in the same manner as in Example 1-1, except that the catalyst a3-1 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1-1 for purifying exhaust gas for an ammonia engine.

[0087] <Temperature characteristic test of a3-1 exhaust gas purification catalyst for ammonia engine> The temperature characteristic test of the catalyst a3-1 for purifying exhaust gas for an ammonia engine was carried out in the same manner as in Example 3. The evaluation results of the catalyst a3-1 for purifying exhaust gas for an ammonia engine are shown in Table 3.

[0088] Comparative Example 4 <Production of exhaust gas purification catalyst a4 for ammonia engine> Except for using zirconia support particles (ZrO2 support particles) instead of CZ support particles, an exhaust gas purification catalyst a4 for an ammonia engine was produced in the same manner as in Comparative Example 3. The proportion of palladium contained in the exhaust gas purification catalyst a4 for an ammonia engine that was supported on Al2O3 support particles was less than 90 mol%. Furthermore, with respect to the total amount of the exhaust gas purification catalyst a4 for an ammonia engine, the content of Pd / ZrO2 support particles was 50 mass%, and the content of Al2O3 support particles was 50 mass%.

[0089] <Preparation of catalyst layer b4 and temperature characteristic test of exhaust gas purification catalyst a4 for ammonia engine> A catalyst layer b4 was produced in the same manner as in Example 1, except that the catalyst a4 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1 for purifying exhaust gas for an ammonia engine. A temperature characteristic test of the catalyst a4 for purifying exhaust gas for an ammonia engine was also carried out in the same manner as in Example 3. The evaluation results of the catalyst a4 for purifying exhaust gas for an ammonia engine are shown in Table 3.

[0090] Comparative Example 4-1 <Production of exhaust gas purification catalyst a4-1 for ammonia engine> ZrO2 support particles as support particles were added to an aqueous solution containing palladium nitrate as a catalytic precious metal precursor and mixed. The mixture was adjusted so that palladium was supported on the ZrO2 support particles at a ratio of 2.5 wt%. The mixture was then dried and calcined, thereby reducing the palladium nitrate as a catalytic precious metal precursor to palladium as a catalytic precious metal, and supporting the palladium on the ZrO2 support particles to produce Pd / ZrO2 support particles. The resulting Pd / ZrO2 support particles were designated as catalyst a4-1 for exhaust gas purification for ammonia engines. The proportion of palladium supported on Al2O3 support particles in the catalyst a4-1 for exhaust gas purification for ammonia engines was less than 90 mol%. The content of Pd / ZrO2 support particles was 100 mass% of the total amount of catalyst a4-1 for exhaust gas purification for ammonia engines.

[0091] <Preparation of catalyst layer b4-1> A catalyst layer b4-1 was produced in the same manner as in Example 1-1, except that the catalyst a4-1 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1-1 for purifying exhaust gas for an ammonia engine.

[0092] <Temperature characteristic test of a4-1 exhaust gas purification catalyst for ammonia engine> The temperature characteristic test of the catalyst a4-1 for purifying exhaust gas for an ammonia engine was carried out in the same manner as in Example 3. The evaluation results of the catalyst a4-1 for purifying exhaust gas for an ammonia engine are shown in Table 3.

[0093] [Table 3]

[0094] Next, an exhaust gas purification catalyst for an ammonia engine, in which palladium as a catalytic noble metal is supported on carrier particles, was investigated.

[0095] The exhaust gas purification catalysts A3-1, a3-1, and a4-1 for ammonia engines in Example 3-1 and Comparative Examples 3-1 and 4-1 are catalysts that do not contain other carrier particles, i.e., catalysts in which the content of catalytic precious metal / carrier particles is 100 mass %. The exhaust gas purification catalyst A3-1 for ammonia engines, in which the proportion of palladium as the catalytic precious metal supported on Al2O3 carrier particles is 90 mol %, has a lower temperature at which the NH3 concentration is halved and a lower NO3 concentration at 500°C than the exhaust gas purification catalysts a3-1 and a4-1 for ammonia engines in which palladium as the catalytic precious metal is not supported on Al2O3 carrier particles. x The integrated values ​​of emission concentrations and N2O emission concentrations were low.

[0096] The exhaust gas purification catalysts A3, A4, a3 and a4 for ammonia engines in Examples 3 and 4 and Comparative Examples 3 and 4 are catalysts containing other carrier particles on which no catalytic precious metal is supported. The exhaust gas purification catalysts A3 and A4 for ammonia engines in which the proportion of palladium as the catalytic precious metal supported on Al2O3 carrier particles is 90 mol % have a lower temperature at which the NH3 concentration is halved and a higher NO concentration at 500°C than the exhaust gas purification catalysts a3 and a4 for ammonia engines in which palladium as the catalytic precious metal is not supported on Al2O3 carrier particles. x The integrated values ​​of emission concentrations and N2O emission concentrations were low.

[0097] Furthermore, when Examples 3, 4, and 3-1 are compared, the catalysts A3 and A4 for purifying exhaust gas for an ammonia engine containing other carrier particles have similar temperatures at which the NH3 concentration is reduced by half compared to the catalyst A3-1 for purifying exhaust gas for an ammonia engine that does not contain other carrier particles, and the NO concentration at 500°C is x The integrated values ​​of emission concentrations and N2O emission concentrations were low.

[0098] As mentioned above, compared to CZ support particles and ZrO2 support particles, by supporting catalytic precious metals on alumina support particles, the activation of catalytic precious metals is promoted, and the production of nitrogen (N2), the main product of the NH3 purification reaction, is promoted. As a result, the temperature at which the NH3 concentration is halved is lowered, and the NOx On the other hand, when the catalytic precious metal is supported on carrier particles with oxygen storage capacity such as CZ carrier particles, nitrogen atoms and oxygen atoms are more likely to bond, which is presumed to have increased the generation of N2O. From the above, it can be seen that an ammonia exhaust gas purification catalyst in which palladium as the catalytic precious metal is supported on Al2O3 carrier particles is able to suppress the emission of unburned NH3 and NO in the exhaust gas at the start of the engine. x It is expected that this will be able to purify the air and reduce N2O emissions.

[0099] Example 5 <Production of exhaust gas purification catalyst A5 for ammonia engine> Al2O3 support particles as support particles were added to an aqueous solution in which platinum nitrate as a catalytic precious metal precursor was dissolved, and mixed. The mixture was adjusted so that platinum was supported at 2.5 wt% relative to the Al2O3 support particles. This mixture was then dried and calcined, thereby reducing the platinum nitrate as a catalytic precious metal precursor to platinum as a catalytic precious metal, and supporting the platinum on the Al2O3 support particles. In this manner, platinum-supported Al2O3 support particles (Pt / Al2O3 support particles) were prepared. Then, Pt / Al2O3 support particles (40 parts by mass) and CZ support particles (40 parts by mass) were mixed to prepare catalyst A5 for purifying exhaust gas for an ammonia engine. The proportion of platinum supported on the Al2O3 support particles in catalyst A5 for purifying exhaust gas for an ammonia engine was 90 mol% or more. Furthermore, the content of Pt / Al2O3 support particles was 50 mass % and the content of CZ support particles was 50 mass % relative to the total amount of the ammonia engine exhaust gas purification catalyst A5.

[0100] <Preparation of catalyst layer B5 and temperature characteristic test of exhaust gas purification catalyst A5 for ammonia engine> A catalyst layer B5 was produced in the same manner as in Example 1, except that the catalyst A5 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1 for purifying exhaust gas for an ammonia engine. A temperature characteristic test of the catalyst A5 for purifying exhaust gas for an ammonia engine was also carried out in the same manner as in Example 3. The evaluation results of the catalyst A5 for purifying exhaust gas for an ammonia engine are shown in Table 4.

[0101] Example 5-1 <Production of exhaust gas purification catalyst A5-1 for ammonia engine> Al2O3 support particles were added to and mixed with an aqueous solution containing platinum nitrate as a catalytic precious metal precursor. The resulting mixture was adjusted so that 2.5 wt% of platinum was supported on the Al2O3 support particles. The resulting mixture was then dried and calcined to reduce the platinum nitrate as a catalytic precious metal precursor to platinum as a catalytic precious metal. The platinum was then supported on the Al2O3 support particles, producing Pt / Al2O3 support particles. The resulting Pt / Al2O3 support particles were designated as catalyst A5-1 for exhaust gas purification for ammonia engines. The proportion of platinum supported on the Al2O3 support particles in the catalyst A5-1 for exhaust gas purification for ammonia engines was 90 mol% or more. The content of the Pt / Al2O3 support particles was 100 mass% of the total weight of catalyst A5-1 for exhaust gas purification for ammonia engines.

[0102] <Preparation of catalyst layer B5-1> A catalyst layer B5-1 was produced in the same manner as in Example 1-1, except that the catalyst A5-1 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1-1 for purifying exhaust gas for an ammonia engine.

[0103] <Temperature characteristic test of exhaust gas purification catalyst A5-1 for ammonia engine> The temperature characteristic test of the catalyst A5-1 for purifying exhaust gas for an ammonia engine was carried out in the same manner as in Example 3. The evaluation results of the catalyst A5-1 for purifying exhaust gas for an ammonia engine are shown in Table 4.

[0104] Example 6 <Production of exhaust gas purification catalyst A6 for ammonia engine> An exhaust gas purification catalyst A6 for an ammonia engine was produced in the same manner as in Example 5, except that ZrO2 support particles were used instead of CZ support particles. The proportion of platinum contained in the exhaust gas purification catalyst A6 for an ammonia engine that was supported on Al2O3 support particles was 90 mol% or more. Furthermore, with respect to the total amount of the exhaust gas purification catalyst A6 for an ammonia engine, the content of Pt / Al2O3 support particles was 50 mass%, and the content of ZrO2 support particles was 50 mass%.

[0105] <Preparation of catalyst layer B6 and temperature characteristic test of exhaust gas purification catalyst A6 for ammonia engine> A catalyst layer B6 was produced in the same manner as in Example 1, except that the catalyst A6 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1 for purifying exhaust gas for an ammonia engine. A temperature characteristic test of the catalyst A6 for purifying exhaust gas for an ammonia engine was also carried out in the same manner as in Example 3. The evaluation results of the catalyst A6 for purifying exhaust gas for an ammonia engine are shown in Table 4.

[0106] Comparative Example 5 <Production of exhaust gas purification catalyst a5 for ammonia engine> CZ support particles were added to an aqueous solution containing platinum nitrate as a catalytic precious metal precursor and mixed. The platinum was supported on the CZ support particles at a ratio of 2.5 wt%. The mixture was then dried and calcined, reducing the platinum nitrate as a catalytic precious metal precursor to platinum as a catalytic precious metal, and supporting the platinum on the CZ support particles. Thus, platinum-supported CZ support particles (Pt / CZ support particles) were prepared. The Pt / CZ support particles (40 parts by mass) were then mixed with Al2O3 support particles (40 parts by mass) to prepare catalyst a5 for purifying exhaust gases for ammonia engines. The proportion of platinum supported on the Al2O3 support particles in catalyst a5 for purifying exhaust gases for ammonia engines was less than 90 mol%. Moreover, the content of Pt / CZ support particles was 50 mass % and the content of Al2O3 support particles was 50 mass % relative to the total amount of the ammonia engine exhaust gas purification catalyst a5.

[0107] <Preparation of catalyst layer b5 and temperature characteristic test of exhaust gas purification catalyst a5 for ammonia engine> A catalyst layer b5 was produced in the same manner as in Example 1, except that the catalyst a5 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1 for purifying exhaust gas for an ammonia engine. A temperature characteristic test of the catalyst a5 for purifying exhaust gas for an ammonia engine was also carried out in the same manner as in Example 3. The evaluation results of the catalyst a5 for purifying exhaust gas for an ammonia engine are shown in Table 4.

[0108] Comparative Example 5-1 <Preparation of exhaust gas purification catalyst a5-1 for ammonia engine> CZ support particles were added to and mixed with an aqueous solution containing platinum nitrate as a catalytic precious metal precursor. The platinum was supported on the CZ support particles at a ratio of 2.5 wt%. This mixture was then dried and calcined to reduce the platinum nitrate as a catalytic precious metal precursor to platinum as a catalytic precious metal, which was then supported on the CZ support particles to produce Pt / CZ support particles. The resulting Pt / CZ support particles were designated catalyst a5-1 for exhaust gas purification for ammonia engines. The proportion of platinum supported on the Al2O3 support particles in the catalyst a5-1 for exhaust gas purification for ammonia engines was less than 90 mol%. The content of Pt / CZ support particles was 100 mass% of the total amount of catalyst a5-1 for exhaust gas purification for ammonia engines.

[0109] <Preparation of catalyst layer b5-1> A catalyst layer b5-1 was produced in the same manner as in Example 1-1, except that the catalyst a5-1 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1-1 for purifying exhaust gas for an ammonia engine.

[0110] <Temperature characteristic test of a5-1 exhaust gas purification catalyst for ammonia engine> The temperature characteristic test of the catalyst a5-1 for purifying exhaust gas for an ammonia engine was carried out in the same manner as in Example 3. The evaluation results of the catalyst a5-1 for purifying exhaust gas for an ammonia engine are shown in Table 4.

[0111] Comparative Example 6 <Production of exhaust gas purification catalyst a6 for ammonia engine> An exhaust gas purification catalyst a6 for an ammonia engine was produced in the same manner as in Comparative Example 5, except that zirconia support particles (ZrO2 support particles) were used instead of CZ support particles. The proportion of platinum contained in the exhaust gas purification catalyst a6 for an ammonia engine that was supported on Al2O3 support particles was less than 90 mol%. Furthermore, with respect to the total amount of the exhaust gas purification catalyst a6 for an ammonia engine, the content of Pt / ZrO2 support particles was 50 mass%, and the content of Al2O3 support particles was 50 mass%.

[0112] <Preparation of catalyst layer b6 and temperature characteristic test of exhaust gas purification catalyst a6 for ammonia engine> A catalyst layer b6 was produced in the same manner as in Example 1, except that the catalyst a6 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1 for purifying exhaust gas for an ammonia engine. A temperature characteristic test of the catalyst a6 for purifying exhaust gas for an ammonia engine was also carried out in the same manner as in Example 3. The evaluation results of the catalyst a6 for purifying exhaust gas for an ammonia engine are shown in Table 4.

[0113] Comparative Example 6-1 <Preparation of exhaust gas purification catalyst a6-1 for ammonia engine> ZrO2 support particles as support particles were added to an aqueous solution containing platinum nitrate as a catalytic precious metal precursor and mixed. The platinum was supported on the ZrO2 support particles at a ratio of 2.5 wt%. This mixture was then dried and calcined, thereby reducing the platinum nitrate as a catalytic precious metal precursor to platinum as a catalytic precious metal, and supporting the platinum on the ZrO2 support particles to produce Pt / ZrO2 support particles. The resulting Pt / ZrO2 support particles were designated as ammonia engine exhaust gas purification catalyst a6-1. The proportion of platinum supported on Al2O3 support particles in the ammonia engine exhaust gas purification catalyst a6-1 was less than 90 mol%. The Pt / ZrO2 support particle content was 100 mass% of the total amount of ammonia engine exhaust gas purification catalyst a6-1.

[0114] <Preparation of catalyst layer b6-1> A catalyst layer b6-1 was produced in the same manner as in Example 1-1, except that the catalyst a6-1 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A1-1 for purifying exhaust gas for an ammonia engine.

[0115] <Temperature characteristic test of a6-1 exhaust gas purification catalyst for ammonia engine> The temperature characteristic test of the catalyst a6-1 for purifying exhaust gas for an ammonia engine was carried out in the same manner as in Example 3. The evaluation results of the catalyst a6-1 for purifying exhaust gas for an ammonia engine are shown in Table 4.

[0116] [Table 4]

[0117] Next, an exhaust gas purification catalyst for an ammonia engine, in which platinum as a catalytic noble metal is supported on carrier particles, was investigated.

[0118] The catalysts A5-1, a5-1, and a6-1 for purifying exhaust gas for ammonia engines in Example 5-1 and Comparative Examples 5-1 and 6-1 are catalysts that do not contain other carrier particles, i.e., catalysts in which the content of catalytic precious metal / carrier particles is 100 mass %. The catalyst A5-1 for purifying exhaust gas for ammonia engines, in which the proportion of platinum as the catalytic precious metal supported on Al2O3 carrier particles is 90 mol %, has a lower temperature at which the NH3 concentration is halved and a lower NO3 concentration at 500°C than the catalysts a5-1 and a6-1 for purifying exhaust gas for ammonia engines, in which platinum as the catalytic precious metal is not supported on Al2O3 carrier particles. x The integrated values ​​of emission concentrations and N2O emission concentrations were low.

[0119] The exhaust gas purification catalysts A5, A6, a5 and a6 for ammonia engines in Examples 5 and 6 and Comparative Examples 5 and 6 are catalysts containing other carrier particles on which no catalytic precious metal is supported. The exhaust gas purification catalysts A5 and A6 for ammonia engines in which the proportion of platinum as the catalytic precious metal supported on Al2O3 carrier particles is 90 mol % have approximately the same temperature at which the NH3 concentration is halved as compared with the exhaust gas purification catalysts a5 and a6 for ammonia engines in which platinum as the catalytic precious metal is not supported on Al2O3 carrier particles, and have a higher NO concentration at 500°C. x The integrated values ​​of emission concentrations and N2O emission concentrations were low.

[0120] Furthermore, when Examples 5, 6, and 5-1 are compared, the catalysts A5 and A6 for purifying exhaust gas for an ammonia engine containing other carrier particles have approximately the same temperature at which the NH3 concentration is halved as compared with the catalyst A5-1 for purifying exhaust gas for an ammonia engine that does not contain other carrier particles, and the NO concentration at 500°C is x The integrated values ​​of emission concentrations and N2O emission concentrations were low.

[0121] As mentioned above, compared to CZ support particles and ZrO2 support particles, by supporting catalytic precious metals on Al2O3 support particles, the activation of catalytic precious metals is promoted, and the production of nitrogen (N2), the main product of the NH3 purification reaction, is promoted. As a result, the temperature at which the NH3 concentration is halved is lowered, and the NO x On the other hand, when the catalytic precious metal is supported on carrier particles with oxygen storage capacity such as CZ carrier particles, nitrogen atoms and oxygen atoms are more likely to bond, which is presumed to have increased the generation of N2O. From the above, it can be seen that an ammonia exhaust gas purification catalyst in which platinum as the catalytic precious metal is supported on Al2O3 carrier particles is able to suppress the emission of unburned NH3 and NO as exhaust gases at the start of the engine. x It is expected that this will be able to purify the air and reduce N2O emissions.

[0122] Although preferred embodiments of the exhaust gas purification catalyst for an ammonia engine, the exhaust gas purification catalyst device for an ammonia engine, and the exhaust gas purification method of the present invention have been described, those skilled in the art will understand that modifications can be made without departing from the scope of the claims. [Explanation of symbols]

[0123] 10. Exhaust gas purification catalyst device for ammonia engine 100 Base material 200 Catalyst layer 210 Exhaust gas purification catalyst for ammonia engine 211 Carrier particles 212 Catalytic precious metals

Claims

1. The catalyst includes support particles and a catalytic noble metal supported on the support particles, the support particles comprise alumina support particles; and 90 mol % or more of the catalytic noble metal is supported on the alumina support particles. Exhaust gas purification catalyst for ammonia engines.

2. 2. The exhaust gas purification catalyst for an ammonia engine according to claim 1, wherein the catalytic noble metal is at least one noble metal selected from the group consisting of rhodium, palladium, and platinum.

3. 2. The exhaust gas purification catalyst for an ammonia engine according to claim 1, wherein the support particles further comprise support particles selected from zirconia support particles, ceria support particles, and combinations thereof.

4. a substrate and a catalyst layer on the substrate; The catalyst layer comprises the exhaust gas purification catalyst for an ammonia engine according to any one of claims 1 to 3. Exhaust gas purification catalyst device for ammonia engines.

5. A method for purifying exhaust gas, comprising bringing exhaust gas emitted from an ammonia engine into contact with the exhaust gas purification catalyst for an ammonia engine according to any one of claims 1 to 3, thereby purifying the exhaust gas.

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