Defect-rich perovskite coupled monatomic catalyst, preparation method and application thereof

Abstract

The application discloses a kind of rich defect perovskite coupling single-atom catalyst and its preparation method and application.The preparation method of the catalyst is that perovskite material doped with trace noble metal is dispersed in deionized water, after adding hydroxyl shielding agent, using ionizing radiation treatment, to introduce the defect that perovskite surface is uniformly distributed and promote the dissolution of trace noble metal (such as Pt, Pd or Au), form high dispersion single-atom catalytic active center.The solution after irradiation is dried and calcined, finally obtain rich defect perovskite coupling single-atom catalyst.The catalyst of the application has excellent catalytic activity and stability in the cooperative removal reaction of catalytic carbon smoke and NO x , especially suitable for automobile exhaust purification, industrial waste gas treatment and diesel engine exhaust emission treatment and other fields, with good application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalyst preparation, in particular to a defect-rich perovskite coupled single-atom catalyst, a preparation method therefor and applications thereof. BACKGROUND

[0002] Carbon soot (PM) and nitrogen oxides (NO x ) are important components in gaseous pollutants such as automobile exhaust and industrial emissions, which have a serious impact on air quality and human health. Therefore, how to effectively control the emission of PM and NO x has become an important issue in environmental protection and sustainable development.

[0003] In recent years, domestic and foreign researchers have carried out a lot of work on how to effectively purify and treat PM and NO x in diesel exhaust. The existing technology mainly aims at the purification of a single pollutant. The treatment of PM mainly adopts the trapping and regeneration technology, which realizes the interception of PM particles in the exhaust by installing a diesel particulate filter (DPF), and oxidizes them into CO2 under the action of a catalyst. The removal of NO x mainly adopts selective catalytic reduction technology (SCR), which uses NH3 or urea as a reducing agent to catalytically convert it into N2 and H2O. However, the single catalytic mechanism limits its removal efficiency. Therefore, developing a catalyst that can effectively remove carbon soot and NO x at the same time has become a hot spot in catalytic technology research.

[0004] Perovskite structure materials have become the focus of research due to their good thermal stability and excellent catalytic performance. However, perovskite catalysts are limited in the catalytic removal of carbon soot and NO x due to the utilization efficiency of their surface defects and catalytic active centers. On the other hand, noble metals have rich d-band holes, excellent adsorption and activation performance for O2 and NO x , which is very beneficial to the catalytic oxidation of carbon soot. However, the high price limits its development and application. One strategy to solve this problem is to improve the atomic economy of noble metals. Single-atom catalysts usually use noble metals as catalytic centers. Due to the strong interaction between the noble metal components and the support, a large number of coordination unsaturated metal ions can be produced, and more active sites can be exposed, so it has very high catalytic activity and selectivity. However, highly dispersed metal atoms have high surface energy and thermodynamic instability, and tend to aggregate into metal clusters or even nanoparticles under high temperature conditions, making it difficult to realize the stable construction of single-atom catalysts. Therefore, the design and development of high-activity and high-stability single-atom catalysts has become the key to the catalytic removal of carbon soot and NO x . SUMMARY

[0005] The present application aims at the deficiencies of conventional catalysts, and provides a defect-rich perovskite coupled single-atom catalyst and a preparation method thereof. Under ionizing radiation conditions, the distribution of defect sites in the perovskite is ensured to be uniform, trace amounts of noble metals in the perovskite are dissolved from the crystal lattice to the surface to form a highly dispersed noble metal single-atom catalyst, and higher catalytic activity and better stability are exhibited. Compared with common chemical methods, the radiation synthesis method for preparing the defect-rich perovskite coupled single-atom catalyst has the advantages of simple operation, strong repeatability, mild reaction conditions (normal temperature and pressure), and suitability for large-scale preparation.

[0006] Another object of the present application is to provide the application of the defect-rich perovskite coupled single-atom catalyst in catalyzing the reaction of simultaneous removal of soot and NO x , which has a good application prospect.

[0007] To solve the problems in the prior art, the technical solution adopted by the present application is as follows:

[0008] The present application provides a preparation method of a defect-rich perovskite coupled single-atom catalyst. A perovskite material doped with trace amounts of noble metals is weighed and dispersed in deionized water to form a mixed solution, a hydroxyl shielding agent is added after uniform dispersion, and the solution is centrifuged and washed after ionizing radiation reaction, and then dried to obtain a solid. The dried solid is calcined in an air atmosphere to obtain the defect-rich perovskite coupled single-atom catalyst.

[0009] Preferably, the chemical formula of the perovskite doped with trace amounts of noble metals is AB 1-x C x O3, wherein A is one or more of a rare earth metal La, a rare earth metal Ce, an alkaline earth metal Sr or an alkaline earth metal Ca, B is one or more of a transition metal Mn, a transition metal Fe, a transition metal Co or a transition metal Ni, C is one of Pt, Pd or Au, and x is 1% to 3%.

[0010] Preferably, the proportion of the perovskite in the mixed solution is 1 to 4 wt.%.

[0011] Preferably, the radiation source of ionizing radiation is 60 one of Co-gamma rays, X-rays or an electron accelerator.

[0012] Preferably, the hydroxyl shielding agent is one of methanol or ethanol, and the content of the hydroxyl shielding agent is 2 to 6 vol.%.

[0013] Preferably, the absorbed dose of radiation is 10 kGy to 200 kGy, and the radiation reaction time is 24 to 72 h.

[0014] Preferably, the calcination temperature is 400 to 600 DEG C, and the time is 2 to 4 h.

[0015] The defect-rich perovskite coupled single-atom catalyst prepared by the preparation method has perovskite as a carrier, ensures uniform distribution of defect sites of the perovskite under ionizing radiation conditions, and enables trace noble metals in the perovskite to dissolve out from a crystal lattice to a surface to form a highly dispersed noble metal single-atom catalyst.

[0016] The defect-rich perovskite coupled single-atom catalyst prepared by the preparation method has high catalytic combustion efficiency of soot, and has high catalytic activity and strong stability. x The defect-rich perovskite coupled single-atom catalyst prepared by the preparation method is applied to cooperative removal of soot and NO

[0017] Preferably, the atmosphere in the application contains 5-20% O2 / N2 and 300-600 ppm NO.

[0018] Beneficial effects:

[0019] Compared with the prior art, the defect-rich perovskite coupled single-atom catalyst, the preparation method and the application thereof have the following advantages:

[0020] (1) The defect-rich perovskite coupled single-atom catalyst is prepared by the radiation synthesis method of the application in one step, has the advantages of simple operation, strong repeatability, mild reaction conditions (normal temperature and pressure), and suitability for large-scale preparation.

[0021] (2) The catalyst synthesized by the application has perovskite as a carrier, ensures uniform distribution of defect sites of the perovskite under ionizing radiation conditions, enables trace noble metals in the perovskite to dissolve out from a crystal lattice to a surface to form a highly dispersed noble metal single-atom catalyst, has high catalytic combustion efficiency of soot, and has high catalytic activity and strong stability.

[0022] (3) The catalyst prepared by the application can be used for cooperative removal of soot and NO x . BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 FIG. 1 is an XRD spectrum of a Pt1 / LaCoO3 catalyst prepared in Example 1 of the application.

[0024] Figure 2 FIG. 2 is an O2-TPD (oxygen temperature programmed desorption) spectrum of catalysts prepared by different processes, wherein (1) is the catalyst Pt1 / LaCoO3 prepared in Example 1 of the application, and (2) is the catalyst I-Pt1 / LaCoO3 prepared in Comparative Example 1.

[0025] Figure 3 FIG. 3 is an SEM (scanning electron microscope) image of catalysts prepared by different preparation methods, wherein (1) is the catalyst Pt1 / LaCoO3 prepared in Example 1 of the application, and (2) is the catalyst I-Pt1 / LaCoO3 prepared in Comparative Example 1.

[0026] Figure 4 The catalytic combustion activity curves of the catalysts prepared by different preparation methods for soot, wherein (1) is the catalyst Pt1 / LaCoO3(prepared in Example 1, the atmosphere containing NO x ), (2) is the catalyst I-Pt1 / LaCoO3(prepared in Comparative Example 1, the atmosphere containing NO x ), and (3) is the catalyst Pt1 / LaCoO3(prepared in Example 1, the atmosphere not containing NO x ). DETAILED DESCRIPTION

[0027] The present application is described in detail by the following specific examples, which should be understood that these specific examples are only for illustration and explanation of the present application, and do not constitute any limitation on the scope of the present application.

[0028] Example 1

[0029] Preparation of the Pt monatomic catalyst coupled with the defect-rich LaCoO3perovskite:

[0030] 8.6602g of La(NO3)3·6H2O, 5.7624g of Co(NO3)2·6H2O, 0.0532g of PtCl2 and 9.2462g of C6H8O7·H2O were weighed and dissolved in 20mL of deionized water, and after stirring uniformly, they were transferred to a 80℃ water bath for heating and continuous stirring until a gel was generated. After foaming at 200℃ for 2h, the sample was finally calcined at 600℃ for 6h to obtain a LaCo 0.99 Pt 0.01 O3 catalyst sample.

[0031] 2g of LaCo 0.99 Pt 0.01 O3 was weighed and dissolved in 200mL of deionized water, and after ultrasonic stirring to form a mixed solution, 12mL of isopropanol was added as an ·OH shielding agent. X-ray was used as an ionizing radiation source, and the irradiation reaction was carried out at an absorbed dose of 50kGy for 36h. After drying, the sample was calcined at 400℃ in an air atmosphere for 2h to obtain a Pt monatomic catalyst coupled with a defect-rich LaCoO3perovskite, which was labeled as Pt1 / LaCoO3.

[0032] The test results are as follows:

[0033] Figure 1 The XRD spectrum of the catalyst Pt1 / LaCoO3prepared by the irradiation method in Example 1 was obtained, and after comparison with the standard spectrum, no obvious diffraction signal of Pt was observed, and all the characteristic peaks were consistent with the standard spectrum of LaCoO3, indicating that the irradiation treatment of the LaCo 0.99 Pt 0.01 O3 catalyst can highly disperse Pt on the surface of LaCoO3.

[0034] Figure 2 (1) is the SEM image of the catalyst Pt1 / LaCoO3 prepared by the radiation method in Example 1. It can be seen from the figure that the Pt1 / LaCoO3 prepared by the radiation method presents an interwoven rice crust structure, which is conducive to the loading of precious metal species on the perovskite surface, and is not prone to migration and aggregation of active components of the catalyst to cause deactivation, thereby further improving the activity and stability of the catalyst. Figure 3 (1) is the O2-TPD (temperature-programmed desorption of oxygen) spectrum of the catalyst Pt1 / LaCoO3 prepared in Example 1. It can be seen from the figure that the desorption peak area at 200-450°C is larger, which indicates that the desorption amount of active oxygen on the surface of the catalyst Pt1 / LaCoO3 is greater.

[0035] 0.1g of Pt1 / LaCoO3 catalyst was mixed with 0.3g of quartz sand and added to a quartz tube with an inner diameter of 8mm in a continuous flow fixed bed. The effect of the catalyst on the soot combustion performance was tested in an atmosphere of 5% O2 / N2 and 400ppm NO. -1 The temperature was raised to 700℃ at a rate of 100℃. Figure 4 As shown in (1), the Pt1 / LaCoO3 catalyst prepared in Example 1 has a significant effect on soot and NO. x It can be seen from the catalytic combustion activity curve that the T 50 (representing the temperature corresponding to 50% soot conversion) is significantly lower (412°C), indicating that the single-atom catalyst prepared by radiation exhibits better catalytic activity.

[0036] Example 2

[0037] Preparation of defect-rich CeNiO3 perovskite coupled with Pd single-atom catalyst:

[0038] 8.6844 g Ce(NO3)3·6H2O, 5.6995 g Ni(NO3)2·6H2O, 0.0701 g PdCl2 and 9.2462 g C6H8O7·H2O were weighed and dissolved in 20 mL deionized water. After stirring evenly, the mixture was transferred to an 80 °C water bath and heated with continuous stirring until a gel was produced. The mixture was then foamed at 200 °C for 2 h and finally calcined at 600 °C for 6 h to obtain CeNi 0.98 Pd 0.02 O3 catalyst sample.

[0039] Weigh 4g CeNi 0.98 Pd 0.02 O3 was dissolved in 200 mL of deionized water and ultrasonically stirred to form a mixed solution. After uniform dispersion, 4 mL of methanol was added as a ·OH shielding agent. 60Co-γ ray as ionizing radiation source, irradiation reaction was carried out for 72 h at an absorbed dose range of 10 kGy, and after drying, calcination was carried out for 3 h in an air atmosphere at 500°C to obtain a defect-rich CeNiO3 perovskite coupled Pd monatomic catalyst, labeled as Pd2 / CeNiO3.

[0040] After 0.1 g of the catalyst Pd2 / CeNiO3 was mixed with 0.3 g of quartz sand and added to a continuous flow fixed bed quartz reactor with an inner diameter of 6 mm, the effect of the catalyst on the combustion performance of soot was tested under an atmosphere of 15% O2 / N2 and 500 ppm NO. The temperature was raised to 700°C at a rate of 5°C·min -1 -1, and the conversion rate of soot was 50% at a reaction temperature of 392°C.

[0041] Example 3

[0042] Preparation of a defect-rich SrMnO3 perovskite coupled Au monatomic catalyst:

[0043] 4.2326 g of Sr(NO3)2, 6.9433 g of Mn(NO3)2(50 wt.% in H2O), 0.1820 g of AuCl3, and 9.2462 g of C6H8O7·H2O were weighed into 20 mL of deionized water, stirred uniformly, then transferred to a 80°C water bath for heating and continuous stirring until a gel was generated, foamed for 2 h at 200°C, and finally calcined for 6 h at 600°C to obtain a SrMn 0.97 Au 0.03 O3 catalyst sample.

[0044] 8 g of SrMn 0.97 Au 0.03 O3 was dissolved in 200 mL of deionized water, ultrasonic stirring to form a mixed solution, 10 mL of ethanol was added as an ·OH shielding agent after uniform dispersion, an electron accelerator was used as an ionizing radiation source, irradiation reaction was carried out for 32 h at an absorbed dose range of 200 kGy, and after drying, calcination was carried out for 4 h in an air atmosphere at 600°C to obtain a defect-rich SrMnO3 perovskite coupled Au monatomic catalyst, labeled as Au3 / SrMnO3.

[0045] After 0.1 g of the catalyst Au3 / SrMnO3 was mixed with 0.3 g of quartz sand and added to a continuous flow fixed bed quartz reactor with an inner diameter of 6 mm, the effect of the catalyst on the combustion performance of soot was tested under an atmosphere of 20% O2 / N2 and 300 ppm NO. The temperature was raised to 700°C at a rate of 5°C·min -1 -1, and the conversion rate of soot was 50% at a reaction temperature of 370°C.

[0046] Example 4

[0047] Preparation of defect-rich LaFeO3 perovskite coupled Pd single-atom catalyst:

[0048] Weigh 8.6602 g of La(NO3)3·6H2O, 7.9184 g of Fe(NO3)3·9H2O, 0.0701 g of PdCl2 and 9.2462 g of C6H8O7·H2O into 20 mL of deionized water, stir uniformly, then transfer to a 80℃ water bath for heating and continuous stirring until a gel is formed, foam at 200℃ for 2h, and finally calcine at 600℃ for 6h to obtain LaFe 0.98 Pd 0.02 O3 catalyst sample.

[0049] Weigh 6 g of LaFe 0.98 Pd 0.02 O3 into 200 mL of deionized water, ultrasonic stirring to form a mixed solution, add 10 mL of isopropanol as ·OH shielding agent after uniform dispersion, use X-ray as ionizing radiation source, irradiate for 48h at an absorbed dose range of 100 kGy, dry and calcine at 500℃ in air atmosphere for 2h to obtain a defect-rich LaFeO3 perovskite coupled Pd single-atom catalyst, marked as Pd2 / LaFeO3.

[0050] Mix 0.1 g of catalyst Pd2 / LaFeO3 with 0.3 g of quartz sand, then add to a continuous flow fixed bed quartz reactor with an inner diameter of 8 mm, test the effect of the catalyst on soot combustion performance under the atmosphere of 10% O2 / N2 and 600 ppm NO. Heat to 700℃ at a rate of 5℃·min -1 The conversion rate of soot is 50% and the reaction temperature is 425℃.

[0051] Example 5

[0052] Preparation of defect-rich CeCoO3 perovskite coupled Au single-atom catalyst:

[0053] Weigh 8.6844 g of Ce(NO3)3·6H2O, 5.6460 g of Co(NO3)2·6H2O, 0.1820 g of AuCl3 and 9.2462 g of C6H8O7·H2O into 20 mL of deionized water, stir uniformly, then transfer to a 80℃ water bath for heating and continuous stirring until a gel is formed, foam at 200℃ for 2h, and finally calcine at 600℃ for 6h to obtain catalyst CeCo 0.97 Au 0.03 O3 sample.

[0054] Weigh 3 g of CeCo 0.97 Au 0.03O3 was dissolved in 200 mL of deionized water, and a mixed solution was formed by ultrasonic stirring. After uniform dispersion, 6 mL of methanol was added as an ·OH shielding agent. An electron accelerator was used as an ionizing radiation source, and irradiation was performed for 60 h at an absorbed dose of 150 kGy. After drying, calcination was performed in an air atmosphere at 450°C for 3 h to obtain a defective SrNiO3 perovskite coupled with a Pt monatomic catalyst, which was labeled as Pt1 / SrNiO3. 60 Co-γ rays were used as an ionizing radiation source, and irradiation was performed for 24 h at an absorbed dose of 80 kGy. After drying, calcination was performed in an air atmosphere at 550°C for 4 h to obtain a defective CeCoO3 perovskite coupled with an Au monatomic catalyst, which was labeled as Au3 / CeCoO3.

[0055] After 0.1 g of the catalyst Au3 / CeCoO3 was mixed with 0.3 g of quartz sand, the mixture was added to a continuous flow fixed-bed quartz reactor with an inner diameter of 8 mm. The effect of the catalyst on the combustion performance of soot was tested in an atmosphere of 5% O2 / N2 and 500 ppm NO. The temperature was increased to 700°C at a rate of 5°C·min-1, and the conversion rate of soot was 50% at a reaction temperature of 347°C. -1

[0056] Example 6

[0057] Preparation of a defective SrNiO3 perovskite coupled with a Pt monatomic catalyst:

[0058] 4.2326 g of Sr(NO3)2, 5.7576 g of Ni(NO3)2·6H2O, 0.0532 g of PtCl2, and 9.2462 g of C6H8O7·H2O were weighed and dissolved in 20 mL of deionized water. After stirring until uniform, the mixture was transferred to a 80°C water bath and heated while continuously stirring until a gel was formed. Foaming was performed at 200°C for 2 h, and finally calcination was performed at 600°C for 6 h to obtain a SrNi 0.99 Pt 0.01 O3 catalyst sample.

[0059] 5 g of SrNi 0.99 Pt 0.01 O3 was dissolved in 200 mL of deionized water, and a mixed solution was formed by ultrasonic stirring. After uniform dispersion, 4 mL of ethanol was added as an ·OH shielding agent. An electron accelerator was used as an ionizing radiation source, and irradiation was performed for 60 h at an absorbed dose of 150 kGy. After drying, calcination was performed in an air atmosphere at 450°C for 3 h to obtain a defective SrNiO3 perovskite coupled with a Pt monatomic catalyst, which was labeled as Pt1 / SrNiO3.

[0060] After 0.1 g of the catalyst Pt1 / SrNiO3 was mixed with 0.3 g of quartz sand, the mixture was added to a continuous flow fixed-bed quartz reactor with an inner diameter of 8 mm. The effect of the catalyst on the combustion performance of soot was tested in an atmosphere of 20% O2 / N2 and 600 ppm NO. The temperature was increased to 700°C at a rate of 5°C·min-1, and the conversion rate of soot was 50% at a reaction temperature of 414°C. -1 ​​

[0061] Comparative Example 1

[0062] LaCoO3 perovskite supported Pt monatomic catalyst prepared by traditional impregnation method:

[0063] 8.6602 g of La(N03)3-6H20, 5.8206 g of Co(N03)2-6H20 and 9.2462 g of C6H8O7-H20 were weighed and dissolved in 20 mL of deionized water, and after stirring uniformly, it was transferred to a 80°C water bath for heating and continuous stirring until a gel was produced, foaming at 200°C for 2h, and finally calcining at 600°C for 6h to obtain a LaCoO3 catalyst sample.

[0064] 1 g of LaCoO3 was weighed and dissolved in 100 mL of deionized water, and after uniform dispersion, 0.0108 g of PtCl2 was added and ultrasonically stirred to form a mixed solution, which was dried and calcined at 500°C in an air atmosphere for 3h to obtain a LaCoO3 perovskite supported Pt monatomic catalyst, marked as I-Pt1 / LaCoO3.

[0065] The test results are as follows:

[0066] Figure 2 Figure (2) is the SEM image of the I-Pt1 / LaCoO3 catalyst prepared by the traditional impregnation method in Comparative Example 1, and from the figure it can be seen that the I-Pt1 / LaCoO3 prepared by the traditional impregnation method presents a clumped block, and the size of the metal particles is not effectively controlled, which is not conducive to the high dispersion of noble metal species on the perovskite surface, thereby weakening the catalytic combustion performance of the catalyst.

[0067] Figure 3 Figure (2) is the O2-TPD (oxygen temperature programmed desorption) spectrum of the catalyst I-Pt1 / LaCoO3 prepared in Comparative Example 1, and from the figure it can be seen that the desorption peak area at 200-450°C is smaller, further indicating that the amount of surface active oxygen desorption is less, and relative to Example 1 (1), it indicates that the traditional impregnation method prepared monatomic catalyst has weaker ability to adsorb and activate oxygen species, further indicating that the radiation prepared monatomic catalyst has stronger ability to adsorb and activate oxygen species.

[0068] 0.1 g of catalyst I-Pt1 / LaCoO3 was mixed with 0.3 g of quartz sand and added to an 8mm inner diameter quartz tube in a continuous flow fixed bed, and the effect of the catalyst on the soot combustion performance was tested under the atmosphere of 20% O2 / N2 and 600ppm NO. The temperature was raised to 700°C at a rate of 5°C·min -1 Figure 4 (2) shows that the I-Pt1 / LaCoO3 catalyst prepared in Comparative Example 1 has weaker catalytic combustion performance on soot and NO x ​The catalytic combustion activity curve shows that the T 50 is obviously higher, indicating that the single-atom catalyst prepared by the traditional impregnation method exhibits poorer catalytic activity (446℃).

[0069] Comparative Example 2

[0070] Preparation of Pd single-atom catalyst supported on CeMnO3 perovskite by precipitation deposition method:

[0071] 8.6844 g of Ce(N03)3·6H2O, 7.158 g of Mn(N03)2(50 wt.% in H2O), and 9.2462 g of C6H8O7·H2O were dissolved in 20 mL of deionized water, and after stirring uniformly, they were transferred to a water bath at 80℃ and heated with continuous stirring until a gel was generated. Foaming was performed at 200℃ for 2 h, and finally, the catalyst CeMnO3 sample was obtained by calcination at 600℃ for 6 h.

[0072] 1 g of CeMnO3 was dissolved in 100 mL of deionized water, and after being uniformly dispersed, 0.0146 g of PdCl2 was added to form a mixed solution by ultrasonic stirring. 100 mL of 1 mol / L urea was added, and the mixture was stirred in a water bath for 6 h. After centrifugal drying, the CeMnO3 perovskite supported Pd single-atom catalyst was obtained by calcination at 400℃ in an air atmosphere for 4 h, and was labeled as D-Pd2 / CeMnO3.

[0073] 0.1 g of the catalyst D-Pd2 / CeMnO3 was mixed with 0.3 g of quartz sand, and then was added to a continuous flow fixed bed quartz reactor with an inner diameter of 8 mm. The effect of the catalyst on the catalytic combustion performance of soot was tested under the atmosphere of 10% O2 / N2 and 500 ppm NO. The temperature was increased to 700℃ at a rate of 5℃·min -1 , and the reaction temperature was 432℃ when the conversion rate of soot was 50%.

[0074] Comparative Example 3

[0075] The Pt1 / LaCoO3 catalyst prepared by the radiation method in Example 1 was taken.

[0076] 0.1 g of the catalyst Pt1 / LaCoO3 was mixed with 0.3 g of quartz sand, and then was added to a continuous flow fixed bed quartz reactor with an inner diameter of 8 mm. The effect of the catalyst on the catalytic combustion performance of soot was tested under the atmosphere of 5% O2 / N2. The temperature was increased to 700℃ at a rate of 5℃·min -1 .

[0077] The results are shown in (3) of the Figure 4 , and the Pt1 / LaCoO3 catalyst prepared in Example 1 exhibited good catalytic combustion performance for soot (without NO xIt can be seen from the activity curves that the T 50 (temperature corresponding to 50% soot conversion) of the Pt1 / LaCoO3 catalyst is significantly higher (473℃), further indicating that the Pt1 / LaCoO3 catalyst has better catalytic activity for the cooperative removal of soot and NO x The Pt1 / LaCoO3 catalyst exhibits better catalytic activity for the cooperative removal of soot and NO

[0078] Table 1 Soot conversion of the catalysts in the temperature programmed oxidation test

[0079]

[0080] In summary, under ionizing radiation, the present application ensures uniform distribution of the perovskite defect sites, and the trace noble metal in the perovskite is dissolved from the crystal lattice to the surface to form a highly dispersed noble metal monatomic catalyst, which has excellent catalytic activity and stability in the catalytic cooperative removal reaction of soot and NO x .

[0081] The above description of the present application and its embodiments is illustrative and not restrictive, and the embodiments shown in the drawings are only one of the embodiments of the present application, and the actual structure is not limited thereto. Therefore, if a person of ordinary skill in the art is inspired by it, without departing from the spirit of the present application, similar structural modes and embodiments can be designed without creativity, which should all belong to the protection scope of the present application.

Claims

1. A method for preparing a defect-rich perovskite coupled single-atom catalyst, characterized in that: The perovskite material doped with a trace amount of precious metal is weighed and dispersed in deionized water to form a mixed solution. After uniform dispersion, a hydroxyl shielding agent is added. After ionizing radiation reaction, centrifugal washing is performed and the solid is obtained after drying. The dried solid is calcined in an air atmosphere to obtain a defect-rich perovskite coupled single-atom catalyst. The chemical formula of the perovskite doped with a trace amount of precious metal is AB 1-x C x O3, wherein A is one or more of rare earth metal La, rare earth metal Ce, alkaline earth metal Sr or alkaline earth metal Ca, B is one or more of transition metal Mn, transition metal Fe, transition metal Co or transition metal Ni, C is one of Pt, Pd or Au, and x is 1% to 3%.

2. The method for preparing a defect-rich perovskite coupled single-atom catalyst according to claim 1, characterized in that: The proportion of perovskite in the mixed solution is 1~4wt.%.

3. The method for preparing a defect-rich perovskite coupled single-atom catalyst according to claim 1, characterized in that: The source of ionizing radiation is 60 One of Co-γ ray, X-ray or electron accelerator.

4. The method for preparing a defect-rich perovskite coupled single-atom catalyst according to claim 1, characterized in that: The hydroxyl shielding agent is one of methanol and ethanol, and the content of the hydroxyl shielding agent is 2-6 vol.%.

5. The method for preparing a defect-rich perovskite coupled single-atom catalyst according to claim 1, characterized in that: The absorbed dose of radiation is 10kGy~200kGy; the radiation reaction time is 24-72h.

6. The method for preparing a defect-rich perovskite coupled single-atom catalyst according to claim 1, characterized in that: The calcination temperature is 400~600℃ and the time is 2~4h.

7. A defect-rich perovskite coupled single-atom catalyst prepared based on the preparation method according to claim 1.

8. The defect-rich perovskite coupled single-atom catalyst according to claim 7 is used to catalyze the reaction of soot and NO x Application in synergistic removal reactions.

9. The use according to claim 8, characterized in that The atmosphere in the application described contains 5-20% O2 / N2 and 300-600 ppm NO.

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