Near-zero-emission tail gas purification system and method suitable for hydrogen-ammonia engine

Abstract

The invention relates to the technical field of tail gas treatment, in particular to a near-zero-emission tail gas purification system suitable for a hydrogen-ammonia engine, which is arranged on a tail gas emission end channel of the hydrogen-ammonia engine and comprises an oxidation catalyst for oxidizing NH3 in tail gas; the selective catalytic reduction trap is used for treating residual NH3 in the tail gas, NOx generated by the engine and NOx generated by the oxidation catalyst and filtering ash and carbon particles in the tail gas; and the low-temperature plasma unit is used for treating NH3 and NOx in the tail gas as well as N2O, residual NOx and residual NH3 generated by the selective catalytic reduction trap. The tail gas discharged by the hydrogen-ammonia engine is sequentially treated by the oxidation catalyst, the selective catalytic reduction trapping treatment and the low-temperature plasma treatment, so that the content of pollutants in the tail gas is nearly zero, and the tail gas is discharged into the atmosphere.

Description

Technical Field

[0001] The present invention relates to the technical field of tail gas treatment, and in particular to a near-zero emission tail gas purification system and method suitable for a hydrogen-ammonia engine. Background Art

[0002] With the advancement of science and technology, more and more research has been carried out on improving traditional propulsion systems, improving energy efficiency and reducing environmental pollution. Hydrogen-ammonia engines have gradually attracted the attention and attention of researchers in this context, and have made a series of breakthroughs.

[0003] A hydrogen-ammonia engine is an engine that uses hydrogen and ammonia as fuel. It is based on the principle of hydrogen and air mixed combustion, and achieves energy conversion by controlling the mixing ratio and ignition method. In this engine, the mixture of hydrogen and ammonia is compressed and enters the combustion chamber. After ignition, it is mixed with air and burned to produce a high-temperature and high-pressure working fluid. This working fluid is fed into a turbine or nozzle to generate thrust to drive aircraft or other applications.

[0004] Hydrogen-ammonia engines have many advantages over traditional fuel engines. First, the energy density generated by the combustion of hydrogen and air is high, which can provide stronger and more lasting thrust. Second, this engine uses renewable energy as fuel, which is sustainable and resource-renewable.

[0005] Based on the above advantages, hydrogen-ammonia engines have broad application prospects in aerospace, unmanned aerial vehicles and other fields. For example, in the aviation field, the use of such engines can reduce the pollutant emissions and noise pollution caused by aircraft to the earth's atmosphere; in unmanned aerial vehicles, their high energy density can provide longer endurance and better control performance.

[0006] The hydrogen-ammonia hybrid fuel engine is a high-efficiency, low-carbon clean power unit. However, its exhaust emissions contain a large amount of unburned ammonia and nitrogen oxides. When using carbon-containing auxiliary fuels, the combustion of auxiliary fuels such as a small amount of lubricating oil will produce carbon monoxide and a small amount of hydrocarbons. These pollutants need to be treated to meet increasingly stringent emission standards. At the same time, the exhaust temperature of hydrogen-ammonia engines is relatively high, and the maximum temperature can reach 700-900°C when the hydrogen fuel ratio is medium or high. In order to respond to global climate change and achieve sustainable development, exhaust pollutant emission regulations are becoming more and more stringent, and the emission requirements for pollutants are also becoming higher and higher. Some exhaust treatments need to achieve near-zero emissions. Conventional exhaust treatment devices generally include oxidation catalytic (DOC) devices and selective catalytic reduction (SCR) devices. When used on hydrogen-ammonia engines, it is difficult to achieve near-zero emissions.

[0007] Patent CN116927934A discloses a device and method based on an ammonia decomposition catalyst, an SCR catalyst section and an ammonia oxidation catalyst section, but the device is complex, the operating temperature environment of the catalytic device is harsh, and it cannot remove the side reaction product N2O and carbon-containing auxiliary fuel (such as a small amount of lubricating oil combustion) or carbon monoxide and a small amount of hydrocarbons produced by incomplete combustion, etc., and cannot achieve near-zero emission requirements under complex working conditions.

[0008] Patent CN117386531A discloses an ammonia engine exhaust reforming treatment system and method that combines a hydrogen ammonia engine, a preset reformer using plasma technology, and a denitrification reactor based on a selective catalytic reduction (SCR) reactor. However, the system and method need to balance the ammonia inlet amount of the reformer and the denitrification reactor by continuously adjusting the ammonia fuel injection amount to meet the NO in the selective catalytic reduction (SCR) reaction. x Therefore, it has the disadvantages of complex equipment, difficult calibration, and inability to remove the by-product N2O generated by the denitrification reactor, which also affects the thermal efficiency of the hydrogen-ammonia engine.

[0009] Therefore, it is necessary to develop a multi-stage exhaust gas purification device suitable for hydrogen-ammonia engines to achieve efficient exhaust gas purification and near-zero emission goals. Summary of the invention

[0010] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a near-zero emission exhaust gas purification system and method suitable for hydrogen-ammonia engines, which is used to solve the problems of the prior art such as complex device, inability to remove N2O and inability to adapt to the high exhaust gas temperature of hydrogen-ammonia engines.

[0011] To achieve the above objectives and other related objectives, the present invention is achieved through the following technical solutions.

[0012] The first aspect of the present invention is to provide a near-zero emission exhaust gas purification system suitable for a hydrogen-ammonia engine, which is arranged in the exhaust gas emission end channel of the hydrogen-ammonia engine, and the exhaust gas purification system comprises:

[0013] Oxidation catalyst, used to oxidize NH3 in exhaust gas;

[0014] Selective catalytic reduction trap is used to remove the remaining NH3 in the exhaust gas and the NO generated by the engine. x , and NO generated by the oxidation catalyst x Treatment, while filtering ash and carbon particles in the exhaust gas;

[0015] Low temperature plasma unit, used for NH3 and NO in tail gas x As well as N2O generated by the selective catalytic reduction trap, residual NO x , and deal with the residual NH3.

[0016] The second aspect of the present invention is to provide a near-zero emission tail gas purification method applicable to a hydrogen-ammonia engine, comprising the following steps:

[0017] (1) Collecting tail gas generated by hydrogen-ammonia engines;

[0018] (2) subjecting the tail gas collected in step (1) to oxidative catalytic treatment to obtain tail gas II;

[0019] (3) subjecting the tail gas 2 obtained in step (2) to a selective catalytic reduction treatment to obtain tail gas 3;

[0020] (4) The tail gas obtained in step (3) is subjected to low-temperature plasma treatment, tested, and discharged into the atmosphere after meeting the standards.

[0021] As described above, the present invention is a near-zero emission tail gas purification system and method suitable for hydrogen-ammonia engines, which has the following features:

[0022] Beneficial effects:

[0023] (1) The present invention provides a near-zero emission exhaust gas purification system suitable for a hydrogen-ammonia engine. The exhaust gas emitted by the hydrogen-ammonia engine is sequentially treated by an oxidation catalyst, a selective catalytic reduction capture treatment, and a low-temperature plasma treatment to achieve near-zero pollutant content in the exhaust gas before being discharged into the atmosphere;

[0024] (2) The present invention provides a near-zero emission exhaust gas purification system suitable for a hydrogen-ammonia engine, which has a simple structure, a simple application method and a simple process, and can achieve near-zero emission requirements under high temperature and complex working conditions without affecting the thermal efficiency of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Shown is a schematic structural diagram of a near-zero emission exhaust gas purification system applicable to a hydrogen-ammonia engine of the present invention.

[0026] The reference numerals are as follows:

[0027] 1. Oxidation catalyst; 2. Selective catalytic reduction trap; 3. Low temperature plasma unit. DETAILED DESCRIPTION

[0028] In order to make the purpose of the invention, technical solutions and beneficial technical effects of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. People familiar with this technology can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0029] The first aspect of the present invention is to provide a near-zero emission exhaust gas purification system suitable for a hydrogen-ammonia engine, which is arranged in the exhaust gas emission end channel of the hydrogen-ammonia engine, and the exhaust gas purification system comprises:

[0030] Oxidation catalyst, used to oxidize NH3 in exhaust gas;

[0031] Selective catalytic reduction trap is used to remove the remaining NH3 in the exhaust gas and the NO generated by the engine. x , and NO generated by the oxidation catalyst x Treatment, while filtering ash and carbon particles in the exhaust gas;

[0032] Low temperature plasma unit, used for NH3 and NO in tail gas x As well as N2O generated by the selective catalytic reduction trap, residual NO x , and deal with the residual NH3.

[0033] The tail gas emitted by the hydrogen-ammonia engine of the present invention is processed in sequence by an oxidation catalyst, a selective catalytic reduction trap, and a low-temperature plasma unit. The oxidation catalyst partially oxidizes the unburned ammonia in the tail gas into NO x , initially reducing the concentration of NH3 in the exhaust gas; the oxidation uses carbon-containing auxiliary fuel (such as a small amount of lubricating oil combustion) to incompletely burn, producing trace amounts of CO and unburned HC, etc.; the selective catalytic reduction trap combines the remaining NH3 in the exhaust gas with the NO generated by the engine x and NO regenerated by oxidation catalyst x The reaction of NH3 and NO x Ultra-low emissions; the low-temperature plasma unit uses pulsed discharge plasma equipment to generate high-energy electrons and free radicals through electrodes at a relatively low temperature, further removing N2O and NO in the exhaust gas. x and residual NH3, etc., thereby achieving near-zero emissions of pollutants in the exhaust gas.

[0034] In some embodiments of the present invention, the residual NH3 is specifically a trace amount of NH3, and the trace amount content is 2-5 ppm.

[0035] In some embodiments of the present invention, the oxidation catalyst comprises an oxidative carrier having an oxidative catalyst coating on its surface; the oxidative carrier is selected from any one of cordierite and silicon carbide.

[0036] In some embodiments of the present invention, the mesh number of the oxidized carrier is ≥400 mesh; specifically, the mesh number of the oxidized carrier can be 400-500 mesh, 500-600 mesh, 600-700 mesh; typically but not limiting, for example, 400 mesh, 500 mesh, 600 mesh, 700 mesh.

[0037] In some embodiments of the present invention, the oxidized carrier is a straight-through type; specifically, the oxidized carrier is a straight-through cordierite honeycomb structure carrier; the present invention has no special restrictions on the source of the straight-through cordierite honeycomb structure carrier, and a commercially available straight-through cordierite honeycomb structure carrier commonly used by those skilled in the art can be used. Specifically, the manufacturer of the straight-through cordierite honeycomb structure carrier of the present invention is Yixing Prince Ceramics Co., Ltd. or Corning Incorporated.

[0038] In some embodiments of the present invention, the coating slurry of the oxidation catalyst coating includes an oxidation catalytic material, platinum and palladium; the oxidation catalytic material is selected from one or more of zirconium oxide, cerium oxide, lanthanum oxide, praseodymium oxide and aluminum oxide, and preferably, the oxidation catalytic material is aluminum oxide. The mass ratio of platinum to palladium is 10:1; the mass ratio of the oxidation catalytic material to palladium is 250-330:1. Specifically, the mass ratio of the oxidation catalytic material to palladium can be 250-300:1, 300-330:1; typically but not limiting, for example, 250:1, 300:1, 330:1. The coating slurry is an aqueous slurry with a solid content of 40%. The mass ratio of platinum to palladium is 5-10:1; specifically, the mass ratio of platinum to palladium can be 5-8:1, 8-10:1; typically but not limiting, for example, 5:1, 8:1, 10:1.

[0039] In some embodiments of the present invention, the method for preparing the oxidized carrier having an oxidized catalyst coating on the surface comprises the following steps: uniformly coating the coating slurry on the oxidized carrier and calcining. Preferably, the calcining temperature is 500-600°C and the calcining time is 2-3h. Preferably, the calcining temperature is 550°C and the calcining time is 2h.

[0040] In some embodiments of the present invention, the selective catalytic reduction trap comprises a reduced carrier having a selective reduction catalyst coating on its surface, and the reduced carrier is selected from any one of cordierite, silicon carbide, and aluminum titanate.

[0041] In some embodiments of the present invention, the mesh number of the reduced carrier is ≥350 mesh; specifically, the mesh number of the reduced carrier is 350-500 mesh, 500-600 mesh, 600-700 mesh; typically but not limiting, for example, 350 mesh, 500 mesh, 600 mesh, 700 mesh.

[0042] In some embodiments of the present invention, the reduced carrier is a wall-flow structure; preferably, the wall thickness of the wall-flow structure is 8-12 mil. Specifically, the wall thickness can be 8-10 mil, 10-12 mil; typically but not limiting, for example, 8 mil, 10 mil, 12 mil. Specifically, the reduced carrier is a wall-flow structure cordierite carrier. The present invention does not specifically limit the source of the wall-flow structure cordierite carrier, and commercially available products of the wall-flow structure cordierite carrier frequently used by those skilled in the art can be used. Specifically, the manufacturer of the wall-flow structure cordierite carrier of the present invention is Corning Incorporated.

[0043] In some embodiments of the present invention, the coating slurry of the selective reduction catalyst coating includes a molecular sieve containing active components such as Cu or Fe. The coating slurry is an aqueous slurry with a solid content of 35%. The thickness of the coating is 1-3 mil. Specifically, the thickness of the coating can be 1-2 mil, 2-3 mil; typically but not limiting, for example, 1 mil, 2 mil, 3 mil. The coating slurry of the selective reduction catalyst coating includes a molecular sieve loaded with active components. The active component is selected from Cu or Fe. Preferably, the percentage of Cu or Fe is 2-5%; the molecular sieve loaded with Cu or Fe can be commercially available or homemade. Specifically, the molecular sieve loaded with Cu or Fe in this application is commercially available, and the manufacturer is Tianjin Paison New Materials Technology Co., Ltd.

[0044] In some embodiments of the present invention, a method for preparing a reduced carrier having a selective reduction catalyst coating on its surface comprises the following steps: uniformly coating the above coating slurry on the carrier, and calcining. Preferably, the calcining temperature is 500-600°C, and the calcining time is 2-3h. Preferably, the calcining temperature is 550°C, and the calcining time is 2h.

[0045] In some embodiments of the present invention, the low-temperature plasma unit includes a power supply device, a high-voltage controller, a reactor, a discharge electrode and a dielectric material; preferably, the low-temperature plasma generator uses a high-voltage pulse power supply to generate plasma, and the module operating voltage is controlled at 10-20kv after the high-voltage controller, the discharge frequency is 20-100HZ, and the plasma power density is 0.1-10W / cm 3 The low-temperature plasma generator is composed of a dielectric barrier discharge reactor.

[0046] In some embodiments of the present invention, after the hydrogen-ammonia engine is started, the exhaust gas passes through the oxidation catalyst, the selective catalytic reduction trap and the low-temperature plasma unit in sequence, wherein after the exhaust gas passes through the oxidation catalyst, the pollutant components NH3 and NO are oxidized to NO xand NO2, while reducing the pollutant component NH3 and increasing the proportion of NO2. Then it enters the selective catalytic reduction trap, and the remaining NH3 and NO in the exhaust gas x The Cu-SSZ-13 coating reacts and converts into N2, H2O and a small amount of N2O. The tail gas treated by device 2 finally enters the low-temperature plasma unit, and the N2O and residual NH3, NO in the tail gas are x Under the action of low temperature plasma, it is decomposed into non-polluting gas. After passing through the above device, the concentration of tail gas pollutants is measured according to the national heavy-duty vehicle pollutant emission limits and measurement methods, among which NO x , N2O, HC, CO, etc. were not detected, and the NH3 concentration was as low as 0.5ppm, achieving the goal of near-zero pollutant emissions in exhaust gas.

[0047] The second aspect of the present invention is to provide a near-zero emission tail gas purification method applicable to a hydrogen-ammonia engine, comprising the following steps:

[0048] (1) Collecting tail gas generated by hydrogen-ammonia engines;

[0049] (2) subjecting the tail gas collected in step (1) to oxidative catalytic treatment to obtain tail gas II;

[0050] (3) subjecting the tail gas 2 obtained in step (2) to a selective catalytic reduction treatment to obtain tail gas 3;

[0051] (4) The tail gas obtained in step (3) is subjected to low-temperature plasma treatment, tested, and discharged into the atmosphere after meeting the standards.

[0052] The present invention is further described below by way of examples, but the scope of the present invention is not limited thereto.

[0053] When the embodiment gives a numerical range, it should be understood that, unless otherwise specified in the present invention, the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those generally understood by those skilled in the art. If specific conditions are not specified in the embodiment, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for all reagents or instruments, they are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, according to the grasp of the prior art by those skilled in the art and the record of the present invention, any method, equipment, and material of the prior art similar or equivalent to the method, equipment, and material in the embodiments of the present invention can also be used to realize the present invention.

[0054] The oxidation catalyst of the present invention is referred to as DOC. The present invention has no special limitation on the source of the oxidation catalyst, and a commercially available oxidation catalyst commonly used by those skilled in the art can be used. Specifically, the manufacturer of the oxidation catalyst is BASF.

[0055] The selective catalytic reduction trap of the present invention is referred to as SDPF. The present invention has no special limitation on the source of the selective catalytic reduction trap, and a commercially available selective catalytic reduction trap commonly used by those skilled in the art can be used. Specifically, the manufacturer of the selective catalytic reduction trap is BASF.

[0056] The low-temperature plasma unit of the present invention is a device for industrial production and processing using low-temperature plasma technology, which can be a low-temperature plasma generator. The present invention has no special restrictions on the source of the low-temperature plasma unit, and a commercially available product of a low-temperature plasma unit frequently used by those skilled in the art can be used. Specifically, the manufacturer of the low-temperature plasma unit is Shandong Huanke Environmental Protection Technology Co., Ltd.

[0057] Example

[0058] Example 1

[0059] This embodiment provides a near-zero emission exhaust gas purification system applicable to a hydrogen-ammonia engine, which is arranged in an exhaust gas emission end channel of the hydrogen-ammonia engine. The exhaust gas purification system includes:

[0060] Oxidation catalyst 1, used for oxidizing NH3 in exhaust gas;

[0061] Selective catalytic reduction trap 2, used to remove the remaining NH3 in the exhaust gas and the NO generated by the engine x , and NO generated by the oxidation catalyst x Treatment, while filtering ash and carbon particles in the exhaust gas;

[0062] Low temperature plasma unit 3, used for NH3, NO in tail gas x As well as N2O generated by the selective catalytic reduction trap, residual NO x , and deal with the residual NH3.

[0063] Example 2

[0064] This embodiment provides a near-zero emission tail gas purification method applicable to a hydrogen-ammonia engine, comprising the following steps:

[0065] (1) Collecting tail gas generated by hydrogen-ammonia engines;

[0066] (2) The exhaust gas collected in step (1) is subjected to oxidation catalytic treatment through an oxidation catalyst 1 to oxidize NH3 in the exhaust gas; exhaust gas 2 is obtained; the oxidation catalyst 1 includes an oxidizing carrier having an oxidizing catalyst coating on its surface; the oxidizing carrier is straight-through cordierite; the mesh size of the oxidizing carrier is 400 mesh; the coating slurry of the oxidizing catalyst coating includes oxidizing catalytic material, platinum and palladium; the oxidizing catalytic material is aluminum oxide, and the mass ratio of platinum to palladium is 10:1; the mass ratio of the oxidizing catalytic material to platinum is 270:1; the coating slurry is an aqueous slurry with a solid content of 40%; the preparation method of the oxidizing carrier having an oxidizing catalyst coating on its surface includes the following steps: uniformly coating the above-mentioned coating slurry on the oxidizing carrier and calcining it. The calcining temperature is 550°C and the calcining time is 2h; the thickness of the coating is 2mil;

[0067] (3) The tail gas obtained in step (2) is subjected to selective catalytic reduction treatment by a selective catalytic reduction trap 2 to remove the remaining NH3 in the tail gas and the NO generated by the engine. x , and NO generated by the oxidation catalyst 1 x Treatment, while filtering the ash and carbon particles in the exhaust gas to obtain exhaust gas three; the selective catalytic reduction trap 2 includes a reduced carrier with a selective reduction catalyst coating on the surface, the reduced carrier is a wall-flow structured cordierite, and the wall thickness is 12 mil; the coating slurry of the selective reduction catalyst coating includes a molecular sieve loaded with Cu; the manufacturer of the molecular sieve loaded with Cu is Tianjin Paison New Materials Technology Co., Ltd.; the coating slurry is an aqueous slurry with a solid content of 35%; the preparation method of the reduced carrier with a selective reduction catalyst coating on the surface includes the following steps: uniformly coating the above-mentioned coating slurry on the carrier, and calcining to obtain. The calcination temperature is 550°C, and the calcination time is 2h; the thickness of the coating is 2mil;

[0068] (4) The tail gas obtained in step (3) is subjected to low-temperature plasma treatment by a low-temperature plasma unit 3 to remove NH3 and NO in the tail gas. x As well as N2O generated by the selective catalytic reduction trap, residual NO x , and the residual NH3 is treated, and then the exhaust pollutant concentration is measured according to the national heavy-duty vehicle pollutant emission limits and measurement methods, including NO x , N2O, HC, CO, etc. were not detected, and the NH3 concentration was 0.5ppm. After meeting the standard, it was discharged into the atmosphere.

[0069] Comparative Example

[0070] Comparative Example 1

[0071] This comparative example provides a near-zero emission tail gas purification method applicable to a hydrogen-ammonia engine, which differs from Example 2 in that step (4) is removed. Specifically, the method comprises the following steps:

[0072] (1) Collecting tail gas generated by hydrogen-ammonia engines;

[0073] (2) passing the tail gas collected in step (1) through an oxidation catalyst 1 for oxidation catalytic treatment to oxidize NH3 in the tail gas to obtain tail gas 2;

[0074] (3) The tail gas obtained in step (2) is subjected to selective catalytic reduction treatment by a selective catalytic reduction trap 2 to remove the remaining NH3 in the tail gas and the NO generated by the engine. x , and NO generated by the oxidation catalyst 1 x The exhaust gas was processed and the ash and carbon particles in the exhaust gas were filtered to obtain exhaust gas 3; then, the exhaust gas was tested according to the national heavy-duty vehicle pollutant emission limits and measurement methods to measure the concentration of exhaust pollutants, among which HC, CO, etc. were not detected, and NO x The emission is 32mg / Kwh, the N2O emission is 13mg / Kwh, and the NH3 concentration is 3ppm.

[0075] Comparative Example 2

[0076] This comparative example provides a near-zero emission tail gas purification method applicable to a hydrogen-ammonia engine, which differs from Example 2 in that it comprises the following steps:

[0077] (1) Collecting tail gas generated by hydrogen-ammonia engines;

[0078] (2) treating the tail gas collected in step (1) with low-temperature plasma by a low-temperature plasma unit 3 to obtain tail gas 2;

[0079] (3) the tail gas 2 obtained in step (2) is subjected to oxidation catalytic treatment by an oxidation catalyst 1 to obtain tail gas 3;

[0080] (4) The tail gas obtained in step (3) is subjected to selective catalytic reduction treatment by a selective catalytic reduction trap 2, and the concentration of tail gas pollutants is measured, wherein HC, CO, etc. are not detected, and NO x The emission is 46mg / Kwh, the N2O emission is 22mg / Kwh, and the NH3 concentration is 5ppm.

[0081] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A near-zero emission tail gas purification system suitable for a hydrogen-ammonia engine, arranged in the tail gas emission end channel of the hydrogen-ammonia engine, characterized in that: The exhaust gas purification system comprises: An oxidation catalyst (1) for oxidizing NH3 in the exhaust gas; The selective catalytic reduction trap (2) is used to remove the remaining NH3 in the exhaust gas and the NO generated by the engine. x , and NO generated by the oxidation catalyst x Treatment, while filtering ash and carbon particles in the exhaust gas; Low temperature plasma unit (3) is used to treat NH3 and NO in the tail gas. x and the N2O generated by the selective catalytic reduction trap (2), the residual NO x , and deal with the residual NH3.

2. The near-zero emission exhaust gas purification system suitable for hydrogen-ammonia engines according to claim 1 is characterized in that: Also includes one or more of the following characteristics: 11) The oxidation catalyst (1) comprises an oxidation-type carrier having an oxidation catalyst coating on its surface; the oxidation-type carrier is selected from any one of cordierite and silicon carbide; 21) The selective catalytic reduction trap (2) comprises a reduced carrier having a selective reduction catalyst coating on its surface, wherein the reduced carrier is selected from any one of cordierite, silicon carbide and aluminum titanate.

3. The near-zero emission exhaust gas purification system suitable for hydrogen-ammonia engines according to claim 2 is characterized in that: Also includes one or more of the following characteristics: 111) The mesh size of the oxidized carrier is ≥400 mesh; 112) The oxidized carrier is a straight-through type; 211) The mesh size of the reduced carrier is ≥350 mesh; 212) The reducing carrier is a wall-flow structure; preferably, the wall thickness of the wall-flow structure is 8-12 mil.

4. The near-zero emission tail gas purification system for hydrogen-ammonia engines according to claim 2 is characterized in that: The coating slurry of the oxidation catalyst coating includes oxidation catalytic material, platinum and palladium; preferably, the oxidation catalytic material is selected from one or more of zirconium oxide, cerium oxide, lanthanum oxide, praseodymium oxide and aluminum oxide.

5. The near-zero emission tail gas purification system for hydrogen-ammonia engines according to claim 4 is characterized in that: The mass ratio of platinum to palladium is 5-10:

1.

6. The near-zero emission tail gas purification system for hydrogen-ammonia engines according to claim 4 is characterized in that: The mass ratio of the oxidation catalyst material to platinum is 250-330:

1.

7. The near-zero emission exhaust gas purification system suitable for hydrogen-ammonia engines according to claim 2 is characterized in that: The coating slurry of the selective reduction catalyst coating layer includes a molecular sieve loaded with active components.

8. The near-zero emission tail gas purification system for hydrogen-ammonia engines according to claim 7 is characterized in that: The active component is selected from Cu or Fe.

9. The near-zero emission tail gas purification system for hydrogen-ammonia engines according to claim 1 is characterized in that: The low-temperature plasma unit includes a power supply device, a high-voltage controller, a reactor, a discharge electrode and a dielectric material; preferably, the low-temperature plasma generator uses a high-voltage pulse power supply to generate plasma, and the module working voltage is controlled at 10-20kv after the high-voltage controller, the discharge frequency is 20-100HZ, and the plasma power density is 0.1-10W / cm 3 .

10. A near-zero emission tail gas purification method for a hydrogen-ammonia engine applicable to the system as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Collecting tail gas generated by hydrogen-ammonia engines; (2) subjecting the tail gas collected in step (1) to oxidative catalytic treatment to obtain tail gas II; (3) subjecting the tail gas 2 obtained in step (2) to a selective catalytic reduction treatment to obtain tail gas 3; (4) The tail gas obtained in step (3) is subjected to low-temperature plasma treatment, tested, and discharged into the atmosphere after meeting the standards.

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