Exhaust gas purification catalyst for ammonia engine

Abstract

To solve the following problem that: an exhaust gas purification catalyst for ammonia engines is contacted with unburned ammonia and nitrogen oxides contained in exhaust gas, which are then purified into nitrogen and water; however, during this purification by the exhaust gas purification catalyst for ammonia engines, nitrous oxide, known as a greenhouse gas, is generated and discharged; and this drawback becomes a particular concern when the exhaust gas composition changes at high temperature; and thus to provide a novel exhaust gas purification catalyst for ammonia engines that can purify unburned ammonia as exhaust gas in oxygen-deficient atmospheres and suppress nitrous oxide emission in oxygen-excess atmospheres, under atmospheric variation between oxygen-deficient and oxygen-excess atmospheres at high-temperature.SOLUTION: An exhaust gas purification catalyst for an ammonia engine comprises ruthenium and / or nickel oxide.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 ammonia engine exhaust gas purification catalysts are used, these exhaust gases are purified into nitrogen (N2) and water (H2O). However, when using an ammonia engine exhaust gas purification catalyst to purify exhaust gases in this way, there is a problem in that nitrous oxide (N2O), a known greenhouse gas, is generated and emitted. This problem is particularly concerning when the exhaust gas composition changes at high temperatures (during drift).

[0007] Therefore, an object of the present invention is to provide an exhaust gas purification catalyst for an ammonia engine, which can purify unburned ammonia (NH) as exhaust gas in an oxygen-deficient atmosphere and can suppress the emission of nitrous oxide (N2O) in an oxygen-excessive atmosphere when the atmosphere fluctuates between an oxygen-deficient atmosphere and an oxygen-excessive atmosphere at high temperatures. [Means for solving the problem]

[0008] The present invention achieves the above object by the following means.

[0009] <Aspect 1> An exhaust gas purification catalyst for an ammonia engine, comprising ruthenium and / or nickel oxide. <Aspect 2> 2. The exhaust gas purification catalyst for an ammonia engine according to aspect 1, wherein the ruthenium is supported on support particles. <Aspect 3> 3. The exhaust gas purification catalyst for an ammonia engine according to embodiment 1 or 2, further comprising at least one noble metal selected from rhodium, platinum, and palladium. <Aspect 4> A catalyst for purifying exhaust gas for an ammonia engine according to aspect 3, wherein the noble metal is supported on carrier particles. <Aspect 5> Aspect 5. The catalyst for exhaust gas purification for an ammonia engine according to aspect 2 or 4, wherein the support particles comprise support particles selected from alumina support particles, zirconia support particles, ceria support particles, silica support particles, titania support particles, and combinations thereof. <Aspect 6> 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 5. Exhaust gas purification catalyst device for ammonia engines. <Aspect 7> 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 5. [Effects of the Invention]

[0010] According to the exhaust gas purification catalyst for an ammonia engine of the present invention, when the atmosphere changes between an oxygen-deficient atmosphere and an oxygen-excessive atmosphere at high temperatures, in the oxygen-deficient atmosphere, unburned ammonia (NH) as exhaust gas can be purified, and in the oxygen-excessive atmosphere, the emission of nitrous oxide (N2O) can be suppressed. [Brief explanation of the drawings]

[0011] [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

[0012] 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.

[0013] <Exhaust gas purification catalyst for ammonia engines> The exhaust gas purification catalyst for an ammonia engine of the present invention comprises: Contains ruthenium and / or nickel oxide.

[0014] According to the exhaust gas purification catalyst for an ammonia engine of the present invention, unburned ammonia (NH3) in the exhaust gas can be purified during high temperature drift, and the emission of nitrous oxide (N2O) can be suppressed.

[0015] Without being limited by theory, it is speculated that by adding ruthenium and / or nickel oxide, which act as an ammonia decomposition hydrogen production catalyst, to an exhaust gas purification catalyst for an ammonia engine, the production of nitrogen (N2), which is the main product of the NH3 purification reaction, can be promoted, and as a result, when the ammonia engine is drifting, unburned NH3 in the exhaust gas can be purified and NO emissions can be suppressed.

[0016] 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.

[0017] 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 case.

[0018] The exhaust gas purification catalyst 210 for an ammonia engine contains ruthenium 212. The ruthenium 212 may be supported on carrier particles 211.

[0019] <Ruthenium, nickel oxide> The exhaust gas purification catalyst for an ammonia engine of the present invention contains ruthenium and / or nickel oxide. Ruthenium and nickel oxide act, for example, as ammonia decomposition hydrogen production catalysts and can promote the production of nitrogen (N), which is the main product of the NH purification reaction.

[0020] (ruthenium) Ruthenium may be supported on, for example, carrier particles or may exist as particles. In the present invention, ruthenium is not particularly limited, but is preferably supported on carrier particles.

[0021] The particle size of ruthenium (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 ruthenium can be determined from the number average particle size in an image taken with a transmission electron microscope (TEM).

[0022] When ruthenium is supported on a support particle, the amount of ruthenium supported may be 0.1% by mass or more, 0.2% by mass or more, 0.3% by mass or more, 0.5% by mass or more, or 1.0% by mass or more, or 10% by mass or less, 8% by mass or less, 6% by mass or less, or 4% by mass or less, relative to the amount of the support particle.

[0023] (nickel oxide) The nickel oxide may be supported on carrier particles, or may exist alone as particles, although there are no particular limitations thereon.

[0024] The particle size of the nickel oxide (secondary particles) may be, for example, 100 nm or more, 200 nm or more, 500 nm or more, 1 μm or more, or 5 μm or more, or 200 μm or less, 150 μm or less, 100 μm or less, 80 μm or less, or 50 μm or less. The particle size of the nickel oxide can be determined as the median size obtained by dynamic light scattering of a suspension in which carrier particles are dispersed in an appropriate liquid medium (e.g., water).

[0025] <Precious metals> The exhaust gas purification catalyst for an ammonia engine may further contain a precious metal. The precious metal is not particularly limited, but can be appropriately selected from those that promote the ammonia purification reaction. Among them, the exhaust gas purification catalyst for an ammonia engine is not particularly limited, but preferably further contains at least one precious metal selected from rhodium, platinum, and palladium.

[0026] The noble metal may be supported on, for example, carrier particles or may exist as particles. In the present invention, the noble metal is not particularly limited, but is preferably supported on carrier particles.

[0027] The particle size of the precious 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 precious metal can be determined from the number average particle size in an image taken with a transmission electron microscope (TEM).

[0028] When the precious metal is supported on the support particles, the precious 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, relative to the support particles.

[0029] <Carrier particles> The support particles are not particularly limited, and known support particles can be appropriately adopted. In the present invention, the support particles are not particularly limited, but preferably include support particles selected from alumina support particles, zirconia support particles, ceria support particles, silica support particles, titania support particles, and combinations thereof.

[0030] The particle size of the carrier 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 carrier particles can be determined as the median diameter obtained by dynamic light scattering of a suspension in which the carrier particles are dispersed in an appropriate liquid medium (for example, water).

[0031] Specifically, the method for supporting ruthenium on the support particles includes, for example, contacting the support particles with a ruthenium precursor in a suitable liquid medium, preferably water, and then drying and calcining the recovered solid content, thereby supporting ruthenium on the support particles. Examples of the ruthenium precursor include, but are not limited to, ruthenium nitrate, ruthenium sulfate, ruthenium chloride, and ruthenium acetate.

[0032] Specifically, the precious metal can be supported on the support particles by contacting the support particles with a precursor of the precious metal in a suitable liquid medium, preferably water, and then drying and calcining the recovered solid. As the precursor of the precious metal, nitrates, sulfates, hydrochlorides, acetates, etc. of the desired precious metal may be used.

[0033] The exhaust gas purification catalyst for an ammonia engine is not particularly limited, but particles of ruthenium and / or nickel oxide may be used as the exhaust gas purification catalyst for an ammonia engine, carrier particles supporting ruthenium and / or nickel oxide may be used as the exhaust gas purification catalyst for an ammonia engine, or carrier particles supporting ruthenium and / or nickel oxide may be mixed in a wet or dry manner with other carrier particles or carrier particles supporting a noble metal 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 atmosphere fluctuates between an oxygen-deficient atmosphere and an oxygen-excessive atmosphere at high temperatures, in the oxygen-deficient atmosphere, it is possible to purify unburned ammonia (NH) as exhaust gas, and in the oxygen-excessive atmosphere, it is possible to suppress the emission of nitrous oxide (N2O).

[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 gases for an ammonia engine includes a substrate 100 and a catalytic layer 200 on the substrate 100. The catalytic layer 200 includes the above-mentioned catalyst for purifying exhaust gases for an ammonia engine of the present invention, and may include a binder as necessary. By including the catalyst for purifying exhaust gases for an ammonia engine of the present invention in the catalytic layer 200, when the atmosphere fluctuates between an oxygen-deficient atmosphere and an oxygen-excessive atmosphere at high temperatures, unburned ammonia (NH3) as exhaust gas can be purified in an oxygen-deficient atmosphere, and the emission of nitrous oxide (N2O) can be suppressed in an oxygen-excessive atmosphere.

[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] Regarding the formation of the catalyst layer, the amount of coating on the substrate is not particularly limited, but may be 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, or 250 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, when the atmosphere fluctuates between an oxygen-deficient atmosphere and an oxygen-excessive atmosphere at high temperatures, unburned ammonia (NH3) in the exhaust gas can be purified in the oxygen-deficient atmosphere, and the emission of nitrous oxide (N2O) can be suppressed in the oxygen-excessive atmosphere.

[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 as support particles to an aqueous solution containing ruthenium nitrate as a ruthenium precursor and rhodium nitrate as a rhodium precursor, and mixed. The Al2O3 support particles were adjusted so that ruthenium was supported at 2.5 wt% and rhodium was supported at 0.25 wt%. The mixed solution was then dried and calcined, whereby the ruthenium nitrate and rhodium nitrate as precursors of ruthenium and rhodium were reduced to ruthenium and rhodium, and the ruthenium and rhodium were supported on the Al2O3 support particles. In this way, an exhaust gas purification catalyst A1 for an ammonia engine was prepared, in which ruthenium and rhodium were supported on the Al2O3 support particles.

[0052] <Preparation of catalyst layer B1> Ammonia engine exhaust gas purification catalyst A1 (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. This slurry was poured into a cordierite honeycomb substrate (φ30 mm × 50 mm) as the 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 41 g / L.

[0053] <Performance evaluation of exhaust gas purification catalyst A1 for ammonia engine> For exhaust gas from an ammonia engine, lean and rich ammonia-containing mixed gases listed in Table 1 were used as model gases. To evaluate the performance of the ammonia engine exhaust gas purification catalyst A1, a catalyst layer B1 containing the ammonia engine exhaust gas purification catalyst A1 was first placed in a thermostatic chamber to react the catalyst layer B1 with the ammonia-containing mixed gas. The catalyst layer B1 was heated to 500°C, and 1% hydrogen gas was then passed through for 5 minutes. The thermostatic chamber was then maintained at 500°C, and a lean ammonia-containing mixed gas listed in Table 1 and a rich ammonia-containing mixed gas listed in Table 1 were alternately passed through for 180 seconds each. In the third cycle, the NO emission concentration was measured 180 seconds after the lean ammonia-containing mixed gas had passed through, and then the NH3 emission concentration was measured 180 seconds after the rich ammonia-containing mixed gas had passed through. For the ammonia engine exhaust gas purification catalyst A1, the N2O emission concentration after the lean ammonia-containing mixed gas was passed through, and the NH3 emission concentration after the rich ammonia-containing mixed gas was passed through were as shown in Table 2.

[0054] [Table 1]

[0055] Example 2 <Preparation of exhaust gas purification catalyst A2 for ammonia engine> The ammonia engine exhaust gas purification catalyst A1 (40 parts by mass) and ceria-zirconia support particles (CZ support particles) (40 parts by mass) were mixed to prepare the ammonia engine exhaust gas purification catalyst A2.

[0056] <Preparation of catalyst layer B2> Ammonia engine exhaust gas purification catalyst A2 (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 ammonia engine exhaust gas purification catalyst A2. 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 ammonia engine exhaust gas purification catalyst A2 on the substrate wall surface. Next, this coating film was dried and fired in an electric furnace to produce catalyst layer B2. Here, the coating amount of catalyst layer B2 was adjusted so that the coating amount on the substrate was 82 g / L.

[0057] <Performance evaluation of exhaust gas purification catalyst A2 for ammonia engine> Except for using a catalyst layer B2 containing the catalyst A2 for exhaust gas purification for ammonia engines instead of the catalyst layer B1 containing the catalyst A1 for exhaust gas purification for ammonia engines, a performance evaluation of the catalyst A2 for exhaust gas purification for ammonia engines was carried out in the same manner as in Example 1. For the catalyst A2 for exhaust gas purification for ammonia engines, the NO emission concentration after flowing a lean composition ammonia-containing mixed gas and the NH3 emission concentration after flowing a rich composition ammonia-containing mixed gas were as shown in Table 2.

[0058] Example 3 <Production of exhaust gas purification catalyst A3 for ammonia engine> Alumina support particles (Al2O3 support particles) as support particles were added to an aqueous solution in which ruthenium nitrate as a ruthenium precursor and platinum nitrate as a platinum precursor were dissolved, and mixed. Here, the mixture was adjusted so that ruthenium was supported at 2.5 wt% and platinum was supported at 2.5 wt% relative to the Al2O3 support particles. Next, this mixed solution was dried and calcined, thereby reducing the ruthenium nitrate and platinum nitrate as precursors of ruthenium and platinum to ruthenium and platinum, and the ruthenium and platinum were supported on the Al2O3 support particles. Next, after the ruthenium and platinum were supported, The Al2O3 carrier particles (40 parts by mass) and the CZ carrier particles (40 parts by mass) were mixed together to prepare an exhaust gas purification catalyst A3 for an ammonia engine.

[0059] <Preparation of catalyst layer B3> A catalyst layer B3 was produced in the same manner as in Example 2, except that the catalyst A3 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A2 for purifying exhaust gas for an ammonia engine.

[0060] <Performance evaluation of exhaust gas purification catalyst A3 for ammonia engine> Except for using a catalyst layer B3 containing the catalyst A3 for exhaust gas purification for ammonia engines instead of the catalyst layer B1 containing the catalyst A1 for exhaust gas purification for ammonia engines, a performance evaluation of the catalyst A3 for exhaust gas purification for ammonia engines was carried out in the same manner as in Example 1. For the catalyst A3 for exhaust gas purification for ammonia engines, the NO emission concentration after flowing a lean composition ammonia-containing mixed gas and the NH3 emission concentration after flowing a rich composition ammonia-containing mixed gas were as shown in Table 2.

[0061] Example 4 <Production of exhaust gas purification catalyst A4 for ammonia engine> Alumina support particles (Al2O3 support particles) as support particles were added to an aqueous solution in which rhodium nitrate, a precursor of rhodium, was dissolved, and mixed. The rhodium was supported at 0.25 wt% relative to the Al2O3 support particles. This mixture was then dried and calcined, thereby reducing the rhodium nitrate as a precursor of rhodium to rhodium, and supporting the rhodium on the Al2O3 support particles. Nickel oxide (20 parts by mass), the rhodium-supported Al2O3 support particles (40 parts by mass), and CZ support particles (40 parts by mass) were then mixed to produce an ammonia engine exhaust gas purification catalyst A4.

[0062] <Preparation of catalyst layer B4> Ammonia engine exhaust gas purification catalyst A4 (100 parts by mass) and an alumina-based binder (3 parts by mass) were mixed and suspended in a solvent to prepare a slurry containing ammonia engine exhaust gas purification catalyst A4. 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 ammonia engine exhaust gas purification catalyst A4 on the substrate wall. Next, this coating film was dried and fired in an electric furnace to produce catalyst layer B4. Here, the coating amount of catalyst layer B4 was adjusted so that the coating amount on the substrate was 103 g / L.

[0063] <Performance evaluation of exhaust gas purification catalyst A4 for ammonia engines> Except for using a catalyst layer B4 containing the catalyst A4 for exhaust gas purification for ammonia engines instead of the catalyst layer B1 containing the catalyst A1 for exhaust gas purification for ammonia engines, a performance evaluation of the catalyst A4 for exhaust gas purification for ammonia engines was carried out in the same manner as in Example 1. For the catalyst A4 for exhaust gas purification for ammonia engines, the NO emission concentration after flowing a lean composition ammonia-containing mixed gas and the NH3 emission concentration after flowing a rich composition ammonia-containing mixed gas were as shown in Table 2.

[0064] Comparative Example 1 <Production of exhaust gas purification catalyst a1 for ammonia engine> Alumina support particles (Al2O3 support particles) as support particles were added to an aqueous solution in which rhodium nitrate, a precursor of rhodium, was dissolved, and mixed. The rhodium was supported at 0.25 wt% relative to the Al2O3 support particles. This mixture was then dried and calcined, whereby the rhodium nitrate, a precursor of rhodium, was reduced to rhodium, and the rhodium was supported on the Al2O3 support particles. The rhodium-supported Al2O3 support particles (40 parts by mass) were then mixed with CZ support particles (40 parts by mass) to produce an exhaust gas purification catalyst a1 for an ammonia engine.

[0065] <Preparation of catalyst layer b1> A catalyst layer b1 was produced in the same manner as in Example 2, except that the catalyst a1 for purifying exhaust gas for an ammonia engine was used instead of the catalyst A2 for purifying exhaust gas for an ammonia engine.

[0066] <Performance evaluation of exhaust gas purification catalyst a1 for ammonia engine> Except for using a catalyst layer b1 containing the catalyst a1 for exhaust gas purification for ammonia engines instead of the catalyst layer B1 containing the catalyst A1 for exhaust gas purification for ammonia engines, a performance evaluation of the catalyst a1 for exhaust gas purification for ammonia engines was carried out in the same manner as in Example 1. For the catalyst a1 for exhaust gas purification for ammonia engines, the NO emission concentration after flowing a lean composition ammonia-containing mixed gas and the NH3 emission concentration after flowing a rich composition ammonia-containing mixed gas were as shown in Table 2.

[0067] [Table 2]

[0068] The exhaust gas purification catalysts for ammonia engines containing ruthenium (Examples 1 to 3) had lower NO emission concentrations in lean ammonia-containing mixed gas compositions and lower NH3 emission concentrations in rich ammonia-containing mixed gas compositions, compared to the exhaust gas purification catalyst for ammonia engines not containing ruthenium (Comparative Example 1). The exhaust gas purification catalyst for ammonia engines containing nickel oxide (Example 4) also showed similar results to the exhaust gas purification catalyst for ammonia engines containing ruthenium.

[0069] By adding ruthenium or nickel oxide, which acts as an ammonia decomposition hydrogen generation catalyst, to the exhaust gas purification catalyst for ammonia engines, the production of nitrogen (N2), the main product of the NH3 purification reaction, is promoted, and it is presumed that this makes it possible to purify unburned NH3 in the exhaust gas and suppress NO emissions when the ammonia-containing mixed gas alternates between a lean composition and a rich composition.

[0070] 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]

[0071] 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 Ruthenium

Claims

1. An exhaust gas purification catalyst for an ammonia engine, comprising ruthenium and / or nickel oxide.

2. 2. The exhaust gas purification catalyst for an ammonia engine according to claim 1, wherein the ruthenium is supported on carrier particles.

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

4. 4. The exhaust gas purification catalyst for an ammonia engine according to claim 3, wherein the noble metal is supported on carrier particles.

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

6. 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 5. Exhaust gas purification catalyst device for ammonia engines.

7. 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 5, thereby purifying the exhaust gas.

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