Diesel vehicle tail gas denitration catalyst and preparation method thereof
Through the combination of elemental alloy oxides such as rare earths, niobium, zirconium, chromium, hafnium and gallium with modified pumice, the biotoxicity, phase change and selectivity problems of diesel vehicle exhaust denitrogenation catalysts are solved, and efficient denitrification and hydrothermal resistance are achieved Aging reduces environmental impact and manufacturing costs.
Patent Information
- Application Number
- CN202411367300.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-29
- Publication Date
- 2024-12-20
AI Technical Summary
Existing diesel vehicle exhaust denitrogenation catalysts have problems such as biotoxic active components, carrier phase transition, reduced activity, high manufacturing cost, large environmental impact, insufficient hydrothermal stability and nitrogen selectivity.
Elemental alloy oxides such as rare earths, niobium, zirconium, chromium, hafnium and gallium are combined with modified pumice, and catalysts are prepared through hydrothermal reaction and composite salt solution impregnation technology to improve the hydrothermal stability and nitrogen selectivity of the catalyst.
It achieves efficient denitrification, strong resistance to hydrothermal aging, reduces environmental impact and manufacturing costs, and is suitable for industrial production.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of catalyst preparation, and in particular to a catalyst for denitration of diesel vehicle exhaust and a preparation method thereof. Background Art
[0002] Diesel engines have low fuel consumption, high efficiency and good reliability. They are widely used in agriculture and transportation, and are also favored by consumers in the field of passenger cars. However, due to the characteristics of oxygen-rich combustion in diesel engines, the nitrogen oxides (NO X ) emissions are high. NOx can cause photochemical smog and acid rain, and is harmful to human health and destroys the ozone layer. It is the main air pollutant in my country. Therefore, the control of NOx is of great significance to improving air quality. How to control nitrogen oxides (NO X ) has become a research hotspot in the field of environmental protection.
[0003] NH 3 Selective catalytic reduction (SCR) technology is a technology to control NO x The core technology is the efficient and stable denitrification catalyst. 3 -SCR denitration catalyst is mainly V 2 O 5 -WO 3 (MoO 3 ) / TiO 2 The catalyst has the following problems: the active component V 2 O 5 It is biologically toxic; and the carrier TiO 2 Phase change (from anatase to rutile) is easy to occur at high temperature, resulting in a significant decrease in catalyst activity. Other types of denitrification catalysts on the market also have more or less technical defects such as high manufacturing cost, great environmental impact, low denitrification activity, poor hydrothermal stability, insufficient nitrogen selectivity, and the ability to resist water and sulfur needs to be further improved.
[0004] In order to solve the above problems, a Chinese invention patent with authorization announcement number CN106964377B discloses an SCR catalyst for denitration of diesel vehicle exhaust and a preparation method thereof, comprising a carrier, an active ingredient and an additive, wherein the carrier is a honeycomb ceramic carrier, and the active ingredient is V 2 O 5 —WO 3 The auxiliary agent is aluminum fluoride. The SCR catalyst for diesel vehicle exhaust denitrification of the invention can reduce SO 2The effect on the catalyst activity can improve the catalyst denitrification efficiency. However, its hydrothermal stability and nitrogen selectivity still need to be further improved.
[0005] It can be seen that the development of a catalyst for denitrification of diesel vehicle exhaust with good denitrification effect, high hydrothermal stability and nitrogen selectivity, and strong resistance to water and sulfur, and its preparation method meets market demand, has broad market value and application prospects, and is of great significance to promoting the development of the field of diesel vehicle exhaust purification treatment. Summary of the invention
[0006] The main purpose of the present invention is to provide a catalyst for denitrification of diesel vehicle exhaust gas, which has good denitrification effect, high hydrothermal stability and nitrogen selectivity, and strong water and sulfur resistance, and a preparation method thereof.
[0007] To achieve the above object, the present invention provides a method for preparing a catalyst for denitrification of diesel vehicle exhaust, comprising the following steps: Step S1, preparation of alloy oxide: disperse rare earth source, niobium source, zirconium source, chromium source, hafnium source and gallium source in an alcohol solvent, stir evenly, slowly add sodium acetate, continue to stir evenly to obtain a mixture, transfer the mixture to a polytetrafluoroethylene-lined hydrothermal reactor, react at 200-220° C. for 15-22 hours; cool to room temperature, wash repeatedly with anhydrous ethanol, dry in a vacuum drying oven at 85-95° C. to constant weight, and then calcine to obtain an alloy oxide; Step S2, preparation of a composite salt solution: dissolving copper nitrate, titanium nitrate and manganese nitrate in water at 60-80° C., and mixing them evenly to prepare a composite salt solution; Step S3, preparation of modified pumice: the pumice is immersed and dried multiple times in the composite salt solution prepared in step S2, the loading amount of the composite salt is 0.5-0.8% of the carrier mass, and the modified pumice is obtained after calcination; Step S4, compounding: the alloy oxide prepared in step S1 and the modified pumice prepared in step S3 are uniformly mixed to obtain a catalyst for denitration of exhaust gas from diesel vehicles.
[0008] Preferably, the mass ratio of the rare earth source, niobium source, zirconium source, chromium source, hafnium source, gallium source, alcohol solvent and sodium acetate in step S1 is (0.1-0.3):0.2:1:(0.2-0.4):(0.03-0.05):(0.01-0.03):(10-20):3.
[0009] Preferably, the rare earth source is at least one of yttrium nitrate, scandium nitrate, cerium nitrate and lanthanum nitrate.
[0010] Preferably, the niobium source is niobium (V) chloride; the zirconium source is zirconium nitrate; the chromium source is chromium nitrate; the hafnium source is hafnium tetranitrate; and the gallium source is gallium nitrate.
[0011] Preferably, the alcohol solvent is at least one of ethanol, ethylene glycol and n-butanol.
[0012] Preferably, the calcination temperature in step S1 is 540-830° C. and the calcination time is 3-5 h.
[0013] Preferably, the mass ratio of copper nitrate, titanium nitrate, manganese nitrate and water in step S2 is (3-5):1:(1-3):(20-40).
[0014] Preferably, the calcination temperature in step S3 is 1050-1220° C. and the calcination time is 1-3 h.
[0015] Preferably, the mass ratio of the alloy oxide to the modified pumice in step S4 is 1:(1-2).
[0016] Another object of the present invention is to provide a catalyst for denitrification of exhaust gas from diesel vehicles made by the above-mentioned method for preparing the catalyst for denitrification of exhaust gas from diesel vehicles.
[0017] Due to the application of the above technical solution, the present invention has the following beneficial effects: (1) The method for preparing the catalyst for denitrification of diesel vehicle exhaust disclosed in the present invention does not require special equipment, requires little capital investment, has a simple process flow, is easy to operate and control, has high preparation efficiency and finished product qualification rate, has little impact on the environment, and is suitable for industrial production.
[0018] (2) The catalyst for denitrification of diesel vehicle exhaust disclosed in the present invention uses rare earth source, niobium source, zirconium source, chromium source, hafnium source and gallium source as raw materials in the alloy oxide, so that the prepared alloy oxide contains rare earth, niobium, zirconium, chromium, hafnium and gallium at the same time. The synergistic effect can give the product the advantages of good denitrification effect, high hydrothermal stability and nitrogen selectivity, and strong water and sulfur resistance.
[0019] (3) The catalyst for denitrification of diesel vehicle exhaust disclosed in the present invention adopts pumice co-modified with copper, titanium and manganese, which cooperates with the alloy oxide to further improve the denitrification effect, hydrothermal stability, nitrogen selectivity and water and sulfur resistance. DETAILED DESCRIPTION
[0020] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.
[0021] The particle size of the pumice used in each embodiment of the present invention is 100 mesh. Example 1
[0022] A method for preparing a catalyst for denitrification of diesel vehicle exhaust comprises the following steps: Step S1, preparation of alloy oxide: disperse rare earth source, niobium source, zirconium source, chromium source, hafnium source and gallium source in an alcohol solvent, stir evenly, slowly add sodium acetate, continue to stir evenly to obtain a mixture, transfer the mixture to a polytetrafluoroethylene-lined hydrothermal reactor, react at 200° C. for 15 hours; cool to room temperature, wash repeatedly with anhydrous ethanol, dry in a vacuum drying oven at 85° C. to constant weight, and then calcine to obtain an alloy oxide; Step S2, preparation of a composite salt solution: dissolving copper nitrate, titanium nitrate and manganese nitrate in 60° C. water, and mixing them evenly to prepare a composite salt solution; Step S3, preparation of modified pumice: the pumice is immersed and dried multiple times in the composite salt solution prepared in step S2, the loading amount of the composite salt is 0.5% of the carrier mass, and the modified pumice is obtained after calcination; Step S4, compounding: the alloy oxide prepared in step S1 and the modified pumice prepared in step S3 are uniformly mixed to obtain a catalyst for denitration of exhaust gas from diesel vehicles.
[0023] The mass ratio of the rare earth source, niobium source, zirconium source, chromium source, hafnium source, gallium source, alcohol solvent and sodium acetate in step S1 is 0.1:0.2:1:0.2:0.03:0.01:10:3; the rare earth source is yttrium nitrate; the niobium source is niobium (V) chloride; the zirconium source is zirconium nitrate; the chromium source is chromium nitrate; the hafnium source is hafnium tetranitrate; the gallium source is gallium nitrate; the alcohol solvent is ethanol; the calcination temperature in step S1 is 540°C and the time is 3h.
[0024] The mass ratio of copper nitrate, titanium nitrate, manganese nitrate and water in step S2 is 3:1:1:20; the calcination temperature in step S3 is 1050° C. and the time is 1 hour; the mass ratio of alloy oxide and modified pumice in step S4 is 1:1.
[0025] A catalyst for denitrification of exhaust gas from diesel vehicles, which is manufactured by adopting the method for preparing the catalyst for denitrification of exhaust gas from diesel vehicles. Example 2
[0026] A method for preparing a catalyst for denitrification of diesel vehicle exhaust comprises the following steps: Step S1, preparation of alloy oxide: disperse rare earth source, niobium source, zirconium source, chromium source, hafnium source and gallium source in an alcohol solvent, stir evenly, slowly add sodium acetate, continue to stir evenly to obtain a mixture, transfer the mixture to a polytetrafluoroethylene-lined hydrothermal reactor, react at 205° C. for 17 hours; cool to room temperature, wash repeatedly with anhydrous ethanol, dry in a vacuum drying oven at 87° C. to constant weight, and then calcine to obtain an alloy oxide; Step S2, preparation of a composite salt solution: dissolving copper nitrate, titanium nitrate and manganese nitrate in 65° C. water, and mixing them evenly to prepare a composite salt solution; Step S3, preparation of modified pumice: the pumice is immersed and dried multiple times in the composite salt solution prepared in step S2, the loading amount of the composite salt is 0.6% of the carrier mass, and the modified pumice is obtained after calcination; Step S4, compounding: the alloy oxide prepared in step S1 and the modified pumice prepared in step S3 are uniformly mixed to obtain a catalyst for denitration of exhaust gas from diesel vehicles.
[0027] The mass ratio of the rare earth source, niobium source, zirconium source, chromium source, hafnium source, gallium source, alcohol solvent and sodium acetate in step S1 is 0.15:0.2:1:0.25:0.035:0.015:13:3; the rare earth source is scandium nitrate; the niobium source is niobium (V) chloride; the zirconium source is zirconium nitrate; the chromium source is chromium nitrate; the hafnium source is hafnium tetranitrate; the gallium source is gallium nitrate; the alcohol solvent is ethylene glycol; the roasting temperature in step S1 is 590°C and the time is 3.5h.
[0028] The mass ratio of copper nitrate, titanium nitrate, manganese nitrate and water in step S2 is 3.5:1:1.5:25; the calcination temperature in step S3 is 1090° C. and the time is 1.5 h; the mass ratio of alloy oxide and modified pumice in step S4 is 1:1.3.
[0029] A catalyst for denitrification of exhaust gas from diesel vehicles, which is manufactured by adopting the method for preparing the catalyst for denitrification of exhaust gas from diesel vehicles. Example 3
[0030] A method for preparing a catalyst for denitrification of diesel vehicle exhaust comprises the following steps: Step S1, preparation of alloy oxide: disperse rare earth source, niobium source, zirconium source, chromium source, hafnium source and gallium source in an alcohol solvent, stir evenly, slowly add sodium acetate, continue to stir evenly to obtain a mixture, transfer the mixture to a polytetrafluoroethylene-lined hydrothermal reactor, react at 210° C. for 19 hours; cool to room temperature, wash repeatedly with anhydrous ethanol, dry in a vacuum drying oven at 90° C. to constant weight, and then calcine to obtain an alloy oxide; Step S2, preparation of a composite salt solution: dissolving copper nitrate, titanium nitrate and manganese nitrate in 70° C. water, and mixing them evenly to prepare a composite salt solution; Step S3, preparation of modified pumice: the pumice is immersed and dried multiple times in the composite salt solution prepared in step S2, the loading amount of the composite salt is 0.65% of the carrier mass, and the modified pumice is obtained after calcination; Step S4, compounding: the alloy oxide prepared in step S1 and the modified pumice prepared in step S3 are uniformly mixed to obtain a catalyst for denitration of exhaust gas from diesel vehicles.
[0031] The mass ratio of the rare earth source, niobium source, zirconium source, chromium source, hafnium source, gallium source, alcohol solvent and sodium acetate in step S1 is 0.2:0.2:1:0.3:0.04:0.02:15:3; the rare earth source is cerium nitrate; the niobium source is niobium (V) chloride; the zirconium source is zirconium nitrate; the chromium source is chromium nitrate; the hafnium source is hafnium tetranitrate; and the gallium source is gallium nitrate.
[0032] The alcohol solvent is n-butanol; the calcination temperature in step S1 is 750° C. and the calcination time is 4 hours.
[0033] The mass ratio of copper nitrate, titanium nitrate, manganese nitrate and water in step S2 is 4:1:2:30; the calcination temperature in step S3 is 1140° C. and the calcination time is 2 hours; the mass ratio of alloy oxide and modified pumice in step S4 is 1:1.5.
[0034] A catalyst for denitrification of exhaust gas from diesel vehicles, which is manufactured by adopting the method for preparing the catalyst for denitrification of exhaust gas from diesel vehicles. Example 4
[0035] A method for preparing a catalyst for denitrification of diesel vehicle exhaust comprises the following steps: Step S1, preparation of alloy oxide: disperse rare earth source, niobium source, zirconium source, chromium source, hafnium source and gallium source in an alcohol solvent, stir evenly, slowly add sodium acetate, continue to stir evenly to obtain a mixture, transfer the mixture to a polytetrafluoroethylene-lined hydrothermal reactor, react at 215° C. for 20 hours; cool to room temperature, wash repeatedly with anhydrous ethanol, dry in a vacuum drying oven at 93° C. to constant weight, and then calcine to obtain an alloy oxide; Step S2, preparation of a composite salt solution: dissolving copper nitrate, titanium nitrate and manganese nitrate in 75° C. water, and mixing them evenly to prepare a composite salt solution; Step S3, preparation of modified pumice: the pumice is immersed and dried multiple times in the composite salt solution prepared in step S2, the loading amount of the composite salt is 0.75% of the carrier mass, and the modified pumice is obtained after calcination; Step S4, compounding: the alloy oxide prepared in step S1 and the modified pumice prepared in step S3 are uniformly mixed to obtain a catalyst for denitration of exhaust gas from diesel vehicles.
[0036] The mass ratio of the rare earth source, niobium source, zirconium source, chromium source, hafnium source, gallium source, alcohol solvent and sodium acetate in step S1 is 0.25:0.2:1:0.35:0.045:0.025:18:3; the rare earth source is a mixture of yttrium nitrate, scandium nitrate, cerium nitrate and lanthanum nitrate in a mass ratio of 1:2:3:1; the niobium source is niobium (V) chloride; the zirconium source is zirconium nitrate; the chromium source is chromium nitrate; the hafnium source is hafnium tetranitrate; and the gallium source is gallium nitrate.
[0037] The alcohol solvent is a mixture of ethanol, ethylene glycol and n-butanol in a mass ratio of 1:2:3; the calcination temperature in step S1 is 810° C. and the calcination time is 4.5 h.
[0038] The mass ratio of copper nitrate, titanium nitrate, manganese nitrate and water in step S2 is 4.5:1:2.5:35; the calcination temperature in step S3 is 1210° C. and the calcination time is 2.5 h; the mass ratio of alloy oxide and modified pumice in step S4 is 1:1.8.
[0039] A catalyst for denitrification of exhaust gas from diesel vehicles, which is manufactured by adopting the method for preparing the catalyst for denitrification of exhaust gas from diesel vehicles. Example 5
[0040] A method for preparing a catalyst for denitrification of diesel vehicle exhaust comprises the following steps: Step S1, preparation of alloy oxide: disperse rare earth source, niobium source, zirconium source, chromium source, hafnium source and gallium source in an alcohol solvent, stir evenly, slowly add sodium acetate, continue to stir evenly to obtain a mixture, transfer the mixture to a polytetrafluoroethylene-lined hydrothermal reactor, react at 220° C. for 22 hours; cool to room temperature, wash repeatedly with anhydrous ethanol, dry in a vacuum drying oven at 95° C. to constant weight, and then calcine to obtain an alloy oxide; Step S2, preparation of a composite salt solution: dissolving copper nitrate, titanium nitrate and manganese nitrate in water at 80° C., and mixing them evenly to prepare a composite salt solution; Step S3, preparation of modified pumice: the pumice is immersed and dried multiple times in the composite salt solution prepared in step S2, the loading amount of the composite salt is 0.8% of the carrier mass, and the modified pumice is obtained after calcination; Step S4, compounding: the alloy oxide prepared in step S1 and the modified pumice prepared in step S3 are uniformly mixed to obtain a catalyst for denitration of exhaust gas from diesel vehicles.
[0041] The mass ratio of the rare earth source, niobium source, zirconium source, chromium source, hafnium source, gallium source, alcohol solvent and sodium acetate in step S1 is 0.3:0.2:1:0.4:0.05:0.03:20:3; the rare earth source is lanthanum nitrate; the niobium source is niobium (V) chloride; the zirconium source is zirconium nitrate; the chromium source is chromium nitrate; the hafnium source is hafnium tetranitrate; and the gallium source is gallium nitrate.
[0042] The alcohol solvent is ethylene glycol; the calcination temperature in step S1 is 830° C. and the calcination time is 5 hours.
[0043] The mass ratio of copper nitrate, titanium nitrate, manganese nitrate and water in step S2 is 5:1:3:40; the calcination temperature in step S3 is 1220° C. and the time is 3 hours; the mass ratio of alloy oxide and modified pumice in step S4 is 1:2.
[0044] A catalyst for denitrification of exhaust gas from diesel vehicles, which is manufactured by adopting the method for preparing the catalyst for denitrification of exhaust gas from diesel vehicles.
[0045] Comparative Example 1 A catalyst for denitrification of diesel vehicle exhaust and a preparation method thereof, which is similar to Example 1, except that no niobium source, hafnium source and titanium nitrate are added.
[0046] Comparative Example 2 A catalyst for denitration of diesel vehicle exhaust and a preparation method thereof, which is similar to Example 1, except that no gallium source, copper nitrate and rare earth source are added.
[0047] In order to further illustrate the beneficial technical effects of the catalyst for denitration of diesel vehicle exhaust involved in each embodiment of the present invention, the catalyst for denitration of diesel vehicle exhaust involved in Examples 1-5 and Comparative Examples 1-2 was tested for relevant performances. The test results are shown in Table 1. The test method is as follows: (1) 0.1 g of each catalyst was placed in a continuous flow fixed bed reactor, and the reaction gas composition was 0.05% NO, 0.05% NH 3 , 5% O 2 , 50ppm SO 2 , nitrogen was used as the balance gas, the reaction gas flow rate was 300 ml / min, and the space velocity was 159000 h -1 , the activity evaluation temperature is 300℃; the conversion rate of nitrogen oxides and nitrogen selectivity are counted and calculated.
[0048] (2) Each product was aged in a hydrothermal aging furnace, the water content of the aging atmosphere was 5%, and the aging temperature was 400°C for 80 hours. The aged samples were tested under the test conditions in (1) and the nitrogen oxide conversion rate and nitrogen selectivity of the aged catalyst products were calculated again.
[0049] It can be seen from Table 1 that the catalyst for denitrification of diesel vehicle exhaust involved in each embodiment of the present invention has more excellent denitrification effect, sulfur resistance and nitrogen selectivity, and stronger resistance to hydrothermal aging. The combined use of niobium source, hafnium source, titanium nitrate, gallium source, copper nitrate and rare earth source is beneficial to improving the above performance.
[0050] Table 1
[0051] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.
Claims
1. A method for preparing a catalyst for denitrification of diesel vehicle exhaust, characterized in that: The steps include: Step S1, preparation of alloy oxide: disperse rare earth source, niobium source, zirconium source, chromium source, hafnium source and gallium source in an alcohol solvent, stir evenly, slowly add sodium acetate, continue to stir evenly to obtain a mixture, transfer the mixture to a polytetrafluoroethylene-lined hydrothermal reactor, react at 200-220° C. for 15-22 hours; cool to room temperature, wash repeatedly with anhydrous ethanol, dry in a vacuum drying oven at 85-95° C. to constant weight, and then calcine to obtain an alloy oxide; Step S2, preparation of a composite salt solution: dissolving copper nitrate, titanium nitrate and manganese nitrate in water at 60-80° C., and mixing them evenly to prepare a composite salt solution; Step S3, preparation of modified pumice: the pumice is immersed and dried multiple times in the composite salt solution prepared in step S2, the loading amount of the composite salt is 0.5-0.8% of the carrier mass, and the modified pumice is obtained after calcination; Step S4, compounding: the alloy oxide prepared in step S1 and the modified pumice prepared in step S3 are uniformly mixed to obtain a catalyst for denitration of exhaust gas from diesel vehicles.
2. The method for preparing a catalyst for denitration of diesel vehicle exhaust according to claim 1, characterized in that: The mass ratio of the rare earth source, niobium source, zirconium source, chromium source, hafnium source, gallium source, alcohol solvent and sodium acetate in step S1 is (0.1-0.3):0.2:1:(0.2-0.4):(0.03-0.05):(0.01-0.03):(10-20):
3.
3. The method for preparing a catalyst for denitration of diesel vehicle exhaust according to claim 1, characterized in that: The rare earth source is at least one of yttrium nitrate, scandium nitrate, cerium nitrate and lanthanum nitrate.
4. The method for preparing a catalyst for denitration of diesel vehicle exhaust according to claim 1, characterized in that: The niobium source is niobium (V) chloride; the zirconium source is zirconium nitrate; the chromium source is chromium nitrate; the hafnium source is hafnium tetranitrate; and the gallium source is gallium nitrate.
5. The method for preparing a catalyst for denitration of diesel vehicle exhaust according to claim 1, characterized in that: The alcohol solvent is at least one of ethanol, ethylene glycol and n-butanol.
6. The method for preparing a catalyst for denitration of diesel vehicle exhaust according to claim 1, characterized in that: The calcination temperature in step S1 is 540-830° C. and the calcination time is 3-5 hours.
7. The method for preparing a catalyst for denitrification of diesel vehicle exhaust according to claim 1, characterized in that: The mass ratio of copper nitrate, titanium nitrate, manganese nitrate and water in step S2 is (3-5):1:(1-3):(20-40).
8. The method for preparing a catalyst for denitration of diesel vehicle exhaust according to claim 1, characterized in that: The calcination temperature in step S3 is 1050-1220° C. and the calcination time is 1-3 h.
9. The method for preparing a catalyst for denitration of diesel vehicle exhaust according to claim 1, characterized in that: The mass ratio of the alloy oxide to the modified pumice in step S4 is 1:(1-2).
10. A catalyst for denitration of exhaust gas from diesel vehicles produced by the method for preparing the catalyst for denitration of exhaust gas from diesel vehicles according to any one of claims 1 to 9.