CN113289629B - Three-dimensional composite pyrochlore ammoxidation catalyst for purifying tail gas of diesel vehicle - Google Patents
Three-dimensional composite pyrochlore ammoxidation catalyst for purifying tail gas of diesel vehicle Download PDFInfo
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Abstract
The invention provides a three-dimensional composite pyrochlore ammoxidation catalyst for purifying tail gas of a diesel vehicle, wherein the molecular formula of the catalyst is Cu x ‑La 2 Ce 2 O 7 Wherein Cu and La 2 Ce 2 O 7 The molar ratio of (2) is x:100, and the value range of x is 1-10. The catalyst disclosed by the invention takes pyrochlore as a carrier, has good high-temperature structural stability, avoids damage to the structural integrity of the catalyst due to overhigh exhaust emission and strong vibration of a vehicle body, and is beneficial to the rapid generation of acid active sites on the surface of the catalyst due to the fact that a large number of lone pair A-site electrons exist in the pyrochlore, so that the capture of ammonia gas is promoted; the catalyst surface is uniformly loaded with Cu metal oxide, so that the defect of free oxygen on the surface of a material in the catalytic reaction process is effectively overcome, the surface mass transfer efficiency of the catalyst is improved, the reaction rate of N-H bond breakage is accelerated, compared with the activity test of the original pyrochlore catalyst, the NH of the pyrochlore loaded with Cu oxide after continuous reaction for 60 hours 3 The rotation rate is more than 80 percent.
Description
Technical Field
The invention belongs to the technical field of automobile exhaust treatment, and particularly relates to a three-dimensional composite pyrochlore ammoxidation catalyst for purifying tail gas of a diesel vehicle.
Background
In recent years, along with the great increase of economic strength and continuous improvement of comprehensive national force in China, the rapid development of the traditional automobile manufacturing industry and the transportation industry is promoted, the diesel vehicle is used as one of core transportation tools in the transportation industry, and the increasing conservation amount tends to bring about more serious tail gas pollution. NH (NH) 3 As one of the harmful gas pollutants at the tail end of the tail gas post-treatment system of the diesel vehicle, a great amount of leakage seriously threatens the survival and development of human beings, and especially has adverse effects on the health (respiratory and nervous system diseases) and the atmosphere (haze pollution), so the development and research of the ammonia purification treatment technology are necessary. At present, the ammonia purification technology for vehicles mainly adopts selective catalytic oxidation (NH) 3 SCO), the method is simple and efficient, has low reaction temperature and low energy consumption, and is very suitable for complex and variable working conditions of diesel vehicle engines. In particular, the catalytic reaction is carried out in the presence of O 2 Under sufficient conditions, the ammonia and the oxygen generate multiphase reaction on the surface of the catalyst to generate H 2 O and N 2 Thereby thoroughly eliminating ammonia. However, during the ammoxidation reaction, NO, N 2 Harmful side reaction products such as O and the like can be accompanied, thereby raising NH 3 N in the SCO reaction 2 Conversion efficiency and selectivity are important in catalyst research.
Currently, the most widely used ammoxidation catalysts are surface-supported promoter particles (noble and transition metal oxides) of silicon-aluminum oxides (γ -Al) 2 O 3 Zeolite or clay). At NH 3 In the SCO reaction, pt, pd, rh, ag and other noble metal elements can realize NH due to higher reaction activation energy 3 SCO high efficiency catalysis. However, high cost and relatively insufficient N 2 Selectivity is considered to be a critical factor limiting the practical use of noble metals. Pyrochlore catalyst (A) of three-dimensional porous structure 2 B 2 O 7 ) Because of its excellent proton conductivity and high temperature structural stability, it is a promising ammonia selective catalytic oxidation material. Due to A 2 B 2 O 7 Removal of lattice oxygen in the unit cell, the presence of a large number of polarizable lone pair a-site electrons is advantageousAcid active sites are rapidly generated on the surface of the catalyst, and capture of ammonia gas is promoted. However, due to the unsaturated vacancy structure with oxygen atom deletion, the mass transfer efficiency of the surface active free oxygen in the thermocatalytic reaction is reduced to a certain extent, so as to ensure higher activity of NH 3 The SCO reaction rate and catalytic stability, require constant replenishment of the catalyst surface active free oxygen consumption. Nano metal oxide particle (MO) carrier is an effective method for promoting the number of active sites of pyrochlore catalyst, can regulate nano metal oxide to solve the surface mass transfer efficiency, and remarkably improves NH 3 Oxidation efficiency.
Disclosure of Invention
In view of the above, the invention aims to provide a three-dimensional composite pyrochlore ammoxidation catalyst for purifying tail gas of a diesel vehicle, which is used for meeting the requirements of high-efficiency catalytic oxidation of NH3 in the tail gas and long-term service life of the catalyst under the complex and changeable working conditions of the engine of the diesel vehicle.
In order to achieve the above purpose, the technical scheme of the invention is realized as follows:
a three-dimensional composite pyrochlore ammoxidation catalyst for purifying tail gas of diesel vehicle, wherein the molecular formula of the catalyst is Cu x -La 2 Ce 2 O 7 Wherein Cu and La 2 Ce 2 O 7 The molar ratio of (2) is x:100, and the value range of x is 1-10.
The preparation method of the three-dimensional composite pyrochlore ammonia oxidation catalyst for purifying the tail gas of the diesel vehicle comprises the following steps of:
(1) Preparation of three-dimensional Structure La 2 Ce 2 O 7 Pyrochlore catalyst support powder;
(2) By combining a three-dimensional structure La 2 Ce 2 O 7 The pyrochlore catalyst carrier powder and the Cu source are put into deionized water, stirred, impregnated, dried and roasted to obtain the required product.
Preferably, the three-dimensional structure La 2 Ce 2 O 7 The preparation method of the pyrochlore catalyst carrier powder comprises the following steps:
(1) Dissolving lanthanum nitrate, cerium nitrate, citric acid and urea in deionized water, and uniformly stirring to obtain a clear and transparent precursor solution;
(2) Rapidly freezing the precursor solution in a refrigerator, transferring to a freeze dryer for vacuum drying, and obtaining white flocculent precursor powder after all liquid phase components are removed;
(3) Calcining the precursor powder, and cooling to room temperature to obtain a three-dimensional structure La 2 Ce 2 O 7 Pyrochlore catalyst support powder.
Preferably, la in the precursor solution 3+ 、Ce 3+ The concentration ratio of the citric acid to the urea is (0.9-1.1): (0.45-0.55): (0.25-0.35).
Preferably, the lanthanum nitrate and cerium nitrate are added in the step (1) in equal amounts.
Preferably, the stirring temperature in the step (1) is 40 ℃, and the stirring time is 30min.
Preferably, the quick freezing temperature in the step (2) is-8 ℃ to-12 ℃, the air pressure of vacuum drying is 0.1Pa to 1Pa, and the vacuum drying time is 20h to 24h.
Preferably, the specific operation steps of the step (3) are as follows: the precursor powder is put into a blast drying box, dried for 3 hours at 180 ℃, then put into a sintering furnace in air atmosphere, heated to 250 ℃ at the speed of 1-3 ℃/min and kept for 1-1.5 hours, heated to 800 ℃ at the speed of 5-6 ℃/min and kept for 1.5-2 hours, and finally naturally cooled to 18-28 ℃.
Preferably, the Cu source in step (2) comprises Cu (NO) 3 ) 2 、Cu[(NH 3 ) 4 ](OH) 2 、Cu(CH 3 COO) 2 One or more of the following.
Preferably, the specific operation steps of the step (2) are as follows: by combining a three-dimensional structure La 2 Ce 2 O 7 Placing pyrochlore catalyst carrier powder and Cu source into 100-200 ml deionized water at a molar ratio of 1:1, stirring for 1.5-2 h, steaming in a water bath at 60-80 ℃ at a rotating speed of 60-100 rpm/min to obtain dry powder, heating the dry powder to 600 ℃ at a rate of 5-6 ℃/min, and preserving heat1.5-2 h to obtain the required product.
Compared with the prior art, the three-dimensional composite pyrochlore ammonia oxidation catalyst for purifying the tail gas of the diesel vehicle has the following advantages:
(1) The catalyst disclosed by the invention takes pyrochlore as a carrier, has good high-temperature structural stability, avoids damage to the structural integrity of the catalyst due to overhigh exhaust emission and strong vibration of a vehicle body, and is beneficial to the rapid generation of acid active sites on the surface of the catalyst due to the fact that a large number of lone pair A-site electrons exist in the pyrochlore, so that the capture of ammonia gas is promoted;
(2) The catalyst surface of the invention is uniformly loaded with Cu metal oxide, thereby effectively improving the shortage of free oxygen on the surface of the material in the catalytic reaction process, improving the surface mass transfer efficiency of the catalyst, accelerating the reaction rate of N-H bond rupture, comparing with the activity test of the original pyrochlore catalyst, continuously reacting for 60 hours and then loading the pyrochlore of Cu oxide with NH 3 The rotation rate is more than 80 percent.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:
FIG. 1 is a microscopic morphology diagram and an element plane distribution diagram of a three-dimensional composite pyrochlore ammoxidation catalyst according to an embodiment of the present invention;
FIG. 2 is an XRD diffraction pattern of a three-dimensional composite pyrochlore ammoxidation catalyst according to an embodiment of the invention;
FIG. 3 is a schematic diagram of NH of a three-dimensional composite pyrochlore ammoxidation catalyst according to an embodiment of the invention 3 A conversion schematic;
FIG. 4 is a schematic diagram of N of a three-dimensional composite pyrochlore ammoxidation catalyst according to an embodiment of the invention 2 A selective schematic.
Detailed Description
Unless defined otherwise, technical terms used in the following examples have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention pertains. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods are conventional methods unless otherwise specified.
The present invention will be described in detail with reference to the following examples and drawings.
Comparative example 1
1. Weighing La (NO) with purity of 99% 3 ) 3 ·6H 2 O and Ce (NO) 3 ) 3 ·6H 2 O each 0.1mol, citric acid CA (C) 6 H 8 O 7 ) 0.05mol, urea (CH) 4 N 2 O) 0.03mol of La of two metal salts in a precursor solution obtained by dissolving 0.03mol of La in 100-500 mL of deionized water (18 MΩ) at 40 ℃ and stirring for 30min until clarification 3+ 、Ce 3+ The ratio of the ion concentration to the molecular concentration of the citric acid and the urea is (0.9-1.1): (0.45-0.55): (0.25-0.35); transferring the precursor solution to a freezer with the temperature of minus 8 ℃ to minus 12 ℃ for quick freezing, and then placing the frozen precursor solution into a freeze dryer for maintaining for 20 to 24 hours under the vacuum condition of 0.1Pa to 1Pa to obtain white flocculent catalyst precursor powder;
2. after the precursor powder is kept for 3 hours in a blowing drying oven at 180 ℃, the precursor powder is placed in a sintering furnace in air atmosphere, the temperature is firstly increased to 250 ℃ from room temperature at the speed of 1 ℃/min to 3 ℃/min and is kept for 1 to 1.5 hours, then the precursor powder is increased to 800 ℃ at the speed of 5 ℃/min to 6 ℃/min and is kept for 1.5 to 2 hours, and finally the precursor powder is naturally cooled to the room temperature of 18 ℃ to 28 ℃ to obtain the three-dimensional structure La 2 Ce 2 O 7 Pyrochlore catalyst supports, i.e. Cu 0 -La 2 Ce 2 O 7 An ammoxidation catalyst, which is marked as Cu-0%;
3. compacting the obtained pyrochlore catalyst carrier powder, sieving with a 40-60-mesh screen to obtain a granular catalyst sample, and weighing 0.5-1 mL of the sample for activity evaluation test; the inner diameter phi of the quartz tube reactor in the activity evaluation device is 16mm, and the length is 400mm; the catalyst sample is subjected to activity test at 50-400 ℃ and the space velocity of the reaction gas is 60000h -1 The gas concentrations are respectively NH 3 500ppm，O 2 5％。
Example 1
1. Weighing La (NO) with purity of 99% 3 ) 3 ·6H 2 O and Ce (NO) 3 ) 3 ·6H 2 O each 0.1mol, citric acid CA (C) 6 H 8 O 7 ) 0.05mol, urea (CH) 4 N 2 O) 0.03mol of La of two metal salts in a precursor solution obtained by dissolving 0.03mol of La in 100-500 mL of deionized water (18 MΩ) at 40 ℃ and stirring for 30min until clarification 3+ ，Ce 3+ The ratio of the ion concentration to the molecular concentration of the citric acid and the urea is (0.9-1.1): (0.45-0.55): (0.25-0.35); transferring the precursor solution to a freezer with the temperature of minus 8 ℃ to minus 12 ℃ for quick freezing, and then placing the frozen precursor solution into a freeze dryer for maintaining for 20 to 24 hours under the vacuum condition of 0.1Pa to 1Pa to obtain white flocculent catalyst precursor powder;
2. after the precursor powder is kept for 3 hours in a blowing drying oven at 180 ℃, the precursor powder is placed in a sintering furnace in air atmosphere, the temperature is firstly increased to 250 ℃ from room temperature at the speed of 1 ℃/min to 3 ℃/min and is kept for 1 to 1.5 hours, then the precursor powder is increased to 800 ℃ at the speed of 5 ℃/min to 6 ℃/min and is kept for 1.5 to 2 hours, and finally the precursor powder is naturally cooled to the room temperature of 18 ℃ to 28 ℃ to obtain the three-dimensional structure La 2 Ce 2 O 7 A pyrochlore catalyst support;
3. 1mmol of Cu source (Cu (NO) 3 ) 2 、Cu[(NH 3 ) 4 ](OH) 2 、Cu(CH 3 COO) 2 ) Dissolved in 100mmol La 2 Ce 2 O 7 Stirring 100-200 mL deionized water of pyrochlore catalyst carrier for 1.5-2 h, wherein the copper source and La 2 Ce 2 O 7 The molar ratio of the pyrochlore catalyst carrier is 1:100; transferring the mixed solution into a flask, and drying in a rotary steaming water bath at 60-80 ℃ at a rotating speed of 60-100 rpm/min; taking out the dried powder, heating the powder from room temperature to 600 ℃ at a speed of 5 ℃/min-6 ℃/min, and preserving the temperature for 1.5 h-2 h to finally obtain the three-dimensional composite structure Cu 1 -La 2 Ce 2 O 7 An ammoxidation catalyst, which is marked as Cu-1%;
4. the obtained three-dimensional composite structure Cu 1 -La 2 Ce 2 O 7 The ammoxidation catalyst powder is pressed and formed by 40 meshes to the outsideSieving with a 60-mesh screen to obtain a granular catalyst sample, and weighing 0.5-1 mL of the catalyst sample for activity evaluation test; the inner diameter phi of the quartz tube reactor in the activity evaluation device is 16mm, and the length is 400mm; the catalyst sample is subjected to activity test at 50-400 ℃ and the space velocity of the reaction gas is 60000h -1 The gas concentrations are respectively NH 3 500ppm，O 2 5％。
Example 2
1. Weighing La (NO) with purity of 99% 3 ) 3 ·6H 2 O and Ce (NO) 3 ) 3 ·6H 2 O each 0.1mol, citric acid CA (C) 6 H 8 O 7 ) 0.05mol, urea (CH) 4 N 2 O) 0.03mol of La of two metal salts in a precursor solution obtained by dissolving 0.03mol of La in 100-500 mL of deionized water (18 MΩ) at 40 ℃ and stirring for 30min until clarification 3+ ，Ce 3+ The ratio of the ion concentration to the molecular concentration of the citric acid and the urea is (0.9-1.1): (0.45-0.55): (0.25-0.35); transferring the precursor solution to a freezer with the temperature of minus 8 ℃ to minus 12 ℃ for quick freezing, and then placing the frozen precursor solution into a freeze dryer for maintaining for 20 to 24 hours under the vacuum condition of 0.1Pa to 1Pa to obtain white flocculent catalyst precursor powder;
2. after the precursor powder is kept for 3 hours in a blowing drying oven at 180 ℃, the precursor powder is placed in a sintering furnace in air atmosphere, the temperature is firstly increased to 250 ℃ from room temperature at the speed of 1 ℃/min to 3 ℃/min and is kept for 1 to 1.5 hours, then the precursor powder is increased to 800 ℃ at the speed of 5 ℃/min to 6 ℃/min and is kept for 1.5 to 2 hours, and finally the precursor powder is naturally cooled to the room temperature of 18 ℃ to 28 ℃ to obtain the three-dimensional structure La 2 Ce 2 O 7 A pyrochlore catalyst support;
3. 5mmol of Cu source (Cu (NO) 3 ) 2 、Cu[(NH 3 ) 4 ](OH) 2 、Cu(CH 3 COO) 2 ) Dissolved in 100mmol La 2 Ce 2 O 7 Stirring 100-200 mL deionized water of pyrochlore catalyst carrier for 1.5-2 h, wherein the copper source and La 2 Ce 2 O 7 The molar ratio of the pyrochlore catalyst carrier is 5:100; transferring the mixed solution into a flask, and drying in a rotary steaming water bath at 60-80 ℃ with the rotating speed of 60rpm/min-100 rpm/min; taking out the dried powder, heating the powder from room temperature to 600 ℃ at a speed of 5 ℃/min-6 ℃/min, and preserving the temperature for 1.5 h-2 h to finally obtain the three-dimensional composite structure Cu 5 -La 2 Ce 2 O 7 An ammoxidation catalyst, which is marked as Cu-5%;
4. the obtained three-dimensional composite structure Cu 5 -La 2 Ce 2 O 7 The ammonia oxidation catalyst powder is pressed and molded, and a granular catalyst sample is obtained after sieving by a screen mesh with 40-60 meshes, and 0.5-1 mL of sample is weighed for activity evaluation test; the inner diameter phi of the quartz tube reactor in the activity evaluation device is 16mm, and the length is 400mm; the catalyst sample is subjected to activity test at 50-400 ℃ and the space velocity of the reaction gas is 60000h -1 The gas concentrations are respectively NH 3 500ppm，O 2 5％。
Example 3
1. Weighing La (NO) with purity of 99% 3 ) 3 ·6H 2 O and Ce (NO) 3 ) 3 ·6H 2 O each 0.1mol, citric acid CA (C) 6 H 8 O 7 ) 0.05mol, urea (CH) 4 N 2 O) 0.03mol of La of two metal salts in a precursor solution obtained by dissolving 0.03mol of La in 100-500 mL of deionized water (18 MΩ) at 40 ℃ and stirring for 30min until clarification 3+ ，Ce 3+ The ratio of the ion concentration to the molecular concentration of the citric acid and the urea is (0.9-1.1): (0.45-0.55): (0.25-0.35); transferring the precursor solution to a freezer with the temperature of minus 8 ℃ to minus 12 ℃ for quick freezing, and then placing the frozen precursor solution into a freeze dryer for maintaining for 20 to 24 hours under the vacuum condition of 0.1Pa to 1Pa to obtain white flocculent catalyst precursor powder;
2. after the precursor powder is kept for 3 hours in a blowing drying oven at 180 ℃, the precursor powder is placed in a sintering furnace in air atmosphere, the temperature is firstly increased to 250 ℃ from room temperature at the speed of 1 ℃/min to 3 ℃/min and is kept for 1 to 1.5 hours, then the precursor powder is increased to 800 ℃ at the speed of 5 ℃/min to 6 ℃/min and is kept for 1.5 to 2 hours, and finally the precursor powder is naturally cooled to the room temperature of 18 ℃ to 28 ℃ to obtain the three-dimensional structure La 2 Ce 2 O 7 A pyrochlore catalyst support;
3. 10mmol of Cu source (Cu (NO) 3 ) 2 、Cu[(NH 3 ) 4 ](OH) 2 、Cu(CH 3 COO) 2 ) Dissolved in 100mmol La 2 Ce 2 O 7 Stirring 100-200 mL deionized water of pyrochlore catalyst carrier for 1.5-2 h, wherein the copper source and La 2 Ce 2 O 7 The molar ratio of the pyrochlore catalyst carrier is 10:100; transferring the mixed solution into a flask, and drying in a rotary steaming water bath at 60-80 ℃ at a rotating speed of 60-100 rpm/min; taking out the dried powder, heating the powder from room temperature to 600 ℃ at a speed of 5 ℃/min-6 ℃/min, and preserving the temperature for 1.5 h-2 h to finally obtain the three-dimensional composite structure Cu 10 -La 2 Ce 2 O 7 An ammoxidation catalyst, which is marked as Cu-10%;
4. the obtained three-dimensional composite structure Cu 10 -La 2 Ce 2 O 7 The ammonia oxidation catalyst powder is pressed and molded, and a granular catalyst sample is obtained after sieving by a screen mesh with 40-60 meshes, and 0.5-1 mL of sample is weighed for activity evaluation test; the inner diameter phi of the quartz tube reactor in the activity evaluation device is 16mm, and the length is 400mm; the catalyst sample is subjected to activity test at 50-400 ℃ and the space velocity of the reaction gas is 60000h -1 The gas concentrations are respectively NH 3 500ppm，O 2 5％。
The test results of comparative example 1 and examples 1-3 are shown in fig. 2-4, the catalyst takes pyrochlore as a carrier, has better high-temperature structural stability, avoids damaging the structural integrity of the catalyst due to overhigh exhaust emission and strong vibration of a vehicle body, and the pyrochlore is beneficial to rapidly generating acid active sites on the surface of the catalyst due to a large number of lone pair A electrons, so as to promote the capture of ammonia gas; the catalyst surface is uniformly loaded with Cu metal oxide, so that the defect of free oxygen on the surface of a material in the catalytic reaction process is effectively overcome, the surface mass transfer efficiency of the catalyst is improved, the reaction rate of N-H bond breakage is accelerated, compared with the activity test of the original pyrochlore catalyst, the NH of the pyrochlore loaded with Cu oxide after continuous reaction for 60 hours 3 The rotation rate is more than 80 percent.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.
Claims (6)
1. A three-dimensional compound pyrochlore ammoxidation catalyst for purifying tail gas of diesel vehicles is characterized in that: the molecular formula of the catalyst is Cu x -La 2 Ce 2 O 7 Wherein Cu and La 2 Ce 2 O 7 The molar ratio of (2) is x:100, x is in the range of 1-10,
the preparation method of the three-dimensional composite pyrochlore ammoxidation catalyst for purifying the tail gas of the diesel vehicle comprises the following steps:
(1) Preparation of three-dimensional Structure La 2 Ce 2 O 7 Pyrochlore catalyst support powder;
(2) By combining a three-dimensional structure La 2 Ce 2 O 7 Placing pyrochlore catalyst carrier powder and Cu source into 100-200 ml deionized water at a molar ratio of 1:1, stirring for 1.5-2 h, steaming in a water bath at 60-80 ℃ at a rotating speed of 60-100 rpm/min to obtain dry powder, heating the dry powder to 600 ℃ at a speed of 5-6 ℃/min and preserving heat for 1.5-2 h to obtain a required product,
the three-dimensional structure La 2 Ce 2 O 7 The preparation method of the pyrochlore catalyst carrier powder comprises the following steps:
s1, dissolving lanthanum nitrate, cerium nitrate, citric acid and urea in deionized water, and uniformly stirring to obtain a clear and transparent precursor solution;
s2, placing the precursor solution into a refrigerator for quick freezing, transferring the precursor solution into a freeze dryer for vacuum drying, and obtaining white flocculent precursor powder after all liquid phase components are removed;
s3, calcining the precursor powder, and cooling to room temperature to obtain a three-dimensional structure La 2 Ce 2 O 7 The pyrochlore catalyst carrier powder comprises the following specific operation steps: the precursor powder is put into a blast drying box, dried for 3 hours at 180 ℃, then put into a sintering furnace in air atmosphere, and heated to the speed of 1-3 ℃/minHeat preservation is carried out for 1 to 1.5 hours at the temperature of 250 ℃, then the temperature is increased to 800 ℃ at the speed of 5 to 6 ℃/min, heat preservation is carried out for 1.5 to 2 hours, and finally natural air cooling is carried out to 18 to 28 ℃.
2. The three-dimensional composite pyrochlore ammoxidation catalyst for purifying exhaust gas of a diesel vehicle according to claim 1, wherein: la in precursor solution 3+ 、Ce 3+ The concentration ratio of the citric acid to the urea is (0.9-1.1): (0.45-0.55): (0.25-0.35).
3. The three-dimensional composite pyrochlore ammoxidation catalyst for purifying exhaust gas of a diesel vehicle according to claim 1, wherein: the lanthanum nitrate and cerium nitrate are added in equal amounts in step S1.
4. The three-dimensional composite pyrochlore ammoxidation catalyst for purifying exhaust gas of a diesel vehicle according to claim 1, wherein: in the step S1, the stirring temperature is 40 ℃, and the stirring time is 30min.
5. The three-dimensional composite pyrochlore ammoxidation catalyst for purifying exhaust gas of a diesel vehicle according to claim 1, wherein: the quick freezing temperature in the step S2 is-8 ℃ to-12 ℃, the vacuum drying air pressure is 0.1Pa to 1Pa, and the vacuum drying time is 20h to 24h.
6. The three-dimensional composite pyrochlore ammoxidation catalyst for diesel vehicle exhaust gas purification of claim 1 wherein the Cu source in step (2) comprises Cu (NO 3 ) 2 、Cu[(NH 3 ) 4 ](OH) 2 、Cu(CH 3 COO) 2 One or more of the following.
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