A method to eliminate NO x PM catalyst and preparation method and application thereof

Abstract

The present invention discloses a catalyst for simultaneously eliminating NO x and PM. The catalyst is a composition composed of a catalyst MnO x / Cu-SSZ-13 for eliminating NO x and a catalyst Ce-Na2Mn3O7 for eliminating PM. The mass percentage content of the catalyst MnO x / Cu-SSZ-13 is 40%, and the mass percentage content of the catalyst Ce-Na2Mn3O7 is 1%. The present invention uses 1% Ce-Na2Mn3O7 and 40% MnOx / Cu-SSZ-13 as catalysts for eliminating PM and NO x respectively. By designing and combining these two catalysts, the two catalysts can perform their respective functions as much as possible without being affected, achieving the purpose of efficiently eliminating PM and NO x in diesel engine exhaust gas in the same catalytic reactor and within the same temperature range.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental catalysis and particularly relates to a method for simultaneously eliminating NO x Catalyst for PM and its preparation method and application. Background Art

[0002] Installing a catalytic exhaust purification device is an effective way to solve the problem of diesel vehicle exhaust aftertreatment. x Pollutants such as PM and NO in the exhaust gas purification device are oxidized or reduced to harmless CO2, H2O and N2. x The elimination process is a two-stage process of a particulate matter filter (DPF) plus a selective catalytic reduction (SCR). In practical applications, this method has the disadvantages of complex process flow, high requirements for equipment, and large space occupation.

[0003] Since Yoshida proposed the simultaneous elimination of NO x After the catalytic technology of PM and NO, it has attracted extensive attention from scientific researchers. At the same time, the elimination technology is expected to use PM in diesel engine exhaust to act as a NO reduction x The reducing agent can achieve NO x At the same time, in NO x The auxiliary atmosphere promotes the catalytic combustion of PM, thereby achieving NO x and PM. However, in actual applications, due to the x Reduction requires a reducing atmosphere, while PM combustion requires an oxidizing atmosphere. There is a "trade off" relationship between the two, and eliminating both at the same time cannot achieve good results.

[0004] In summary, how to further improve NO through catalyst design? x Improving the elimination efficiency and reducing PM combustion temperature is a severe challenge. Summary of the invention

[0005] In view of this, the present invention discloses a method for simultaneously eliminating NO x Catalyst for PM and its preparation method and application to achieve NO reduction within the exhaust temperature range of diesel vehicle exhaust x Simultaneous elimination with PM.

[0006] The technical solution provided by the present invention is specifically:

[0007] In a first aspect, the present invention provides a method for simultaneously eliminating NO x The catalyst for removing NO x Catalyst MnO x / Cu-SSZ-13 and a catalyst Ce-Na2Mn3O7 for eliminating PM.

[0008] Furthermore, the catalyst MnO x The mass percentage of / Cu-SSZ-13 is 40%, and the mass percentage of the catalyst Ce-Na2Mn3O7 is 1%.

[0009] Furthermore, the catalyst MnO x The average diameters of / Cu-SSZ-13 and catalyst Ce-Na2Mn3O7 are 400nm-500nm, respectively, and the shapes are walnut-shaped.

[0010] In a second aspect, the present invention provides a method for preparing the catalyst, wherein the catalyst MnO x / Cu-SSZ-13 is obtained by impregnating equal volumes of manganese oxide on the Cu-SSZ-13 molecular sieve, and the catalyst Ce-Na2Mn3O7 is prepared by a foaming method using 50% manganese nitrate aqueous solution, sodium nitrate, cerium nitrate and glucose as raw materials.

[0011] In a third aspect, the present invention provides a method for simultaneously eliminating NO x The application of catalysts to remove PM can also be used to remove NO in diesel exhaust. x and PM.

[0012] Further, the application method is: 40% MnO x / Cu-SSZ-13, 1% Ce-Na2Mn3O7 were placed in the same reaction tube, 40% MnO x / Cu-SSZ-13 is in the upper part of the reaction tube, 1% Ce-Na2Mn3O7 is in the upper part of the reaction tube, and the two catalysts are separated by quartz wool; both ends of the two catalysts are also provided with quartz wool layers;

[0013] Among them, 1% Ce-Na2Mn3O7 catalyst is mixed with carbon soot particles PM, the mass ratio of 1% Ce-Na2Mn3O7 catalyst to carbon soot particles PM is 10:1, and the mass ratio of 40% MnOx / Cu-SSZ-13 and 1% Ce-Na2Mn3O7 catalyst is 1:1.

[0014] The invention provides a method for simultaneously eliminating NO x The catalyst for removing PM and NO, and its preparation method and application, the present invention uses 1% Ce-Na2Mn3O7 and 40% MnOx / Cu-SSZ-13 as catalysts for removing PM and NO respectively. xThe catalysts of the two catalysts are designed and combined to maximize the two catalysts to perform their respective functions without affecting each other, achieving the same temperature range for PM and NO in diesel engine exhaust in the same catalytic reactor. x The purpose of efficient elimination.

[0015] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a scanning electron microscope photograph of the 1% Ce-Na2Mn3O7 catalyst provided in Example 1 of the present invention;

[0019] Figure 2 This is a scanning electron microscope photo of the 40% MnOx / Cu-SSZ-13 catalyst provided in Example 2 of the present invention;

[0020] Figure 3 A schematic diagram of the combination of two catalysts provided in Example 3 of the present invention in a reaction tube;

[0021] Figure 4 A catalytic combustion PM activity test diagram provided in Example 4 of the present invention;

[0022] Figure 5 The elimination of NO provided in Example 4 of the present invention x NO conversion rate diagram;

[0023] Figure 6 The elimination of NO provided in Example 4 of the present invention x N2 selectivity map;

[0024] Figure 7 The catalyst mass provided in Example 4 of the present invention is 0.1g, and PM and NO are eliminated simultaneously. x Effect picture. DETAILED DESCRIPTION

[0025] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present invention. Instead, they are merely examples of systems consistent with some aspects of the present invention as detailed in the appended claims.

[0026] In order to achieve NO x Simultaneous elimination of NO and PM. First, this embodiment provides a method for simultaneously eliminating NO x The catalyst is used to remove NO x Catalyst MnO x / Cu-SSZ-13 and Ce-Na2Mn3O7, a catalyst for eliminating PM.

[0027] More preferably, the catalyst MnO x The mass percentage of / Cu-SSZ-13 is 40%, and the mass percentage of catalyst Ce-Na2Mn3O7 is 1%.

[0028] The above catalyst MnO x The average diameters of / Cu-SSZ-13 and catalyst Ce-Na2Mn3O7 are 400nm-500nm, respectively, and the shapes are walnut-shaped.

[0029] In this embodiment, NH3 is used as a reducing agent, and 1% Ce-Na2Mn3O7 and 40% MnO x / Cu-SSZ-13 as the removal of PM and NO x The catalysts of the present invention are designed and combined to make the two catalysts perform their respective functions as much as possible without affecting each other, and to achieve the same temperature range in the same catalytic reactor for the reduction of PM and NO in diesel engine exhaust. x Efficient elimination.

[0030] In a second aspect, this embodiment also provides a method for preparing the above-mentioned combined catalyst, wherein the elimination of NO x 40% MnO x / The preparation method of the Cu-SSZ-13 catalyst is as follows: manganese oxide is loaded on the Cu-SSZ-13 molecular sieve by equal volume impregnation; the catalyst has an average diameter of 400nm-500nm and a walnut-like shape.

[0031] The 1% Ce-Na2Mn3O7 catalyst for PM elimination is composed of sodium, manganese, cerium and oxygen. The catalyst is mainly prepared by a simple foaming method using low-cost 50% manganese nitrate aqueous solution, sodium nitrate, cerium nitrate and glucose as raw materials;

[0032] In the third aspect, this embodiment also provides the application of the above catalyst, and the above combined catalyst can be applied to NO in diesel vehicle exhaust. x and PM are eliminated simultaneously; preferably, the masses of the two catalysts can be 0.05g, 0.1g, and 0.2g respectively, and the mass of PM is 0.01g.

[0033] The above catalyst combination is used to simultaneously eliminate PM and NO in diesel vehicle exhaust x When the mass ratio of 40% MnOx / Cu-SSZ-13 catalyst and 1% Ce-Na2Mn3O7 catalyst is 1:1, both can be selected to be 0.1g, PM is mixed with sodium cerium manganese oxide, the mass ratio of sodium cerium manganese oxide catalyst to PM is 10:1, and the contact mode is loose contact, which can achieve NO within the exhaust temperature range of diesel vehicles. x and PM simultaneously and efficiently eliminates them.

[0034] In this embodiment, when the mass of both catalysts is 0.1g, the temperature window for NO conversion to reach 90% is 140-408°C, and the peak temperature of PM combustion is 348°C, achieving the simultaneous elimination of NOx and PM within the exhaust temperature range of diesel vehicles.

[0035] In order to better illustrate the technical means and product effects of the present invention, the preferred embodiments of the present invention are described below.

[0036] Example 1

[0037] Preparation of 1% Ce-Na2Mn3O7 catalyst

[0038] A certain amount of 50% manganese nitrate aqueous solution, sodium nitrate and cerium nitrate hexahydrate are weighed and dissolved in a certain amount of water according to a stoichiometric ratio. After the solution is completely dissolved, a certain amount of glucose is added to the above solution, and then placed on a stirrer for stirring and mixing. The stirring time is 3 hours. The precursor solution obtained after stirring is placed in an oven at 80°C for drying for 12-24 hours. The dried sample is placed in a muffle furnace and calcined at 550°C for 4 hours to obtain a Ce-doped sodium manganese composite oxide Na2Mn3O7 catalyst material.

[0039] Example 2

[0040] Preparation of 40% MnOx / Cu-SSZ-13 Catalyst

[0041] Dissolve the ammonium chloride particles in the adamantane solution, and then add aluminum isopropoxide. After dissolving at room temperature, add tetraethyl orthosilicate dropwise and stir rapidly in a sealed polyethylene beaker at room temperature for 20 minutes to form a clear solution. Then, evaporate the transparent sol in an open polyethylene container at 90°C for 5 hours to obtain a dry gel for subsequent steam-assisted crystallization. Transfer the dry gel into a sealed high-pressure reactor and transfer it to an oven preheated to 160°, and keep it at 160°C for 24 hours. The product is then washed and dried to obtain SSZ-13, and ion exchange is performed using copper nitrate to obtain Cu-SSZ-13. Weigh a certain amount of 50% manganese nitrate aqueous solution and add an appropriate amount of deionized water as required. Impregnate an equal volume of it on the Cu-SSZ-13 molecular sieve to obtain the following: Figure 2 40% MnOx / Cu-SSZ-13 catalyst shown.

[0042] Example 3

[0043] The prepared catalyst is arranged in a combined manner according to the present invention and used to simultaneously eliminate PM and NO in diesel vehicle exhaust. x The specific reaction scheme is as follows:

[0044] Combined installation of two catalysts

[0045] Weigh 0.05-0.2g of 1% Ce-Na2Mn3O7 catalyst and 0.01g of carbon smoke particles, mix them and grind them with a spatula to make the catalyst and carbon smoke in loose contact. Put them into a quartz tube, place about 5mm thick quartz wool, and then put 0.05-0.2g of 40% MnOx / Cu-SSZ-13 catalyst. The catalyst and both ends of the reaction tube are also blocked with quartz wool ( Figure 3 ). The mass ratio of 40% MnOx / Cu-SSZ-13 and 1% Ce-Na2Mn3O7 catalyst is 1:1;

[0046] Specific implementation 4

[0047] Evaluation method of catalyst activity: using infrared spectroscopy detection system, the catalyst adopts fixed bed method.

[0048] Specific steps: The catalyst was evaluated for NH3-SCR denitrification and PM combustion activity by combining HP-WF microreactor (Nanjing Haoerpu Company) and ThermoFisher NicoletiS50 Fourier transform infrared spectroscopy (real-time analysis of tail gas). The reaction was carried out in the microreactor, and the temperature was measured by a thermocouple inserted into the catalyst bed. Test steps: The above-assembled reaction tube was loaded into the reactor, and the sample was adsorbed in the reaction atmosphere at 50℃-80℃ for 40 minutes until the corresponding gas peak appeared in the infrared spectrum. Then the furnace temperature was raised from 80℃ to 600℃ at a heating rate of 2℃ / min. The feed gas composition was NO (1000ppm), NH3 (1000ppm), 5vol% O2 and N2 balance gas. The gas flow rate was controlled by a flowmeter, and the total flow rate was 100mL / min. The gas products were analyzed online by ThermoFisher's Fourier transform infrared spectroscopy, which was equipped with a gas cell with an optical path of 3m and corresponding infrared analysis software for quantitative calculation.

[0049] Evaluation method: The catalytic ability of the catalyst is defined by different indicators for different reactants. x The removal efficiency is defined by the window where the NO conversion rate reaches 90%, and the activity of catalyzing the combustion of PM is expressed by the peak temperature of CO2. The catalytic activity of catalysts of different mass is shown in the following table. As the mass of the catalyst increases, the temperature window where the NO conversion rate reaches 90% continues to widen, and the PM combustion temperature continues to increase. Comprehensively considered, when the catalyst dosage is 0.1g, it has a higher practical value.

[0050] Table 2 40%MnO x / Cu-SSZ-13 catalyst for simultaneous elimination of NO x Performance testing with PM

[0051]

[0052] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the claims.

Claims

1. A method for simultaneously eliminating NO using a catalyst x The method with PM is characterized in that The catalyst is used to eliminate NO x Catalyst MnO x / Cu-SSZ-13 and a catalyst Ce-Na2Mn3O7 for eliminating PM; the catalyst MnO x / The mass percentage of Cu-SSZ-13 is 40%, and the mass percentage of the catalyst Ce-Na2Mn3O7 is 1%; The catalyst MnO x / Cu-SSZ-13 has an average diameter of 400 nm-500 nm and a walnut-like shape; the catalyst MnO x / Cu-SSZ-13 is obtained by impregnating equal volumes of manganese oxide on the Cu-SSZ-13 molecular sieve, and the catalyst Ce-Na2Mn3O7 is prepared by a foaming method using 50% manganese nitrate aqueous solution, sodium nitrate, cerium nitrate and glucose as raw materials; The catalyst is used to simultaneously eliminate NO in diesel vehicle exhaust x and PM; The method comprises: mixing two catalysts 40% MnO x / Cu-SSZ-13, 1% Ce-Na2Mn3O7 were placed in the same reaction tube, 40% MnO x / Cu-SSZ-13 is in the upper part of the reaction tube, 1% Ce-Na2Mn3O7 is in the lower part of the reaction tube, and the two catalysts are separated by quartz wool; quartz wool layers are also provided at both ends of the two catalysts; the 1% Ce-Na2Mn3O7 catalyst is mixed with carbon smoke particles PM, the mass ratio of 1% Ce-Na2Mn3O7 catalyst to carbon smoke particles PM is 10:1, and the mass ratio of 40% MnOx / Cu-SSZ-13 and 1% Ce-Na2Mn3O7 catalyst is 1:1.

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