Catalyst as well as preparation method and application thereof

Abstract

The embodiment of the invention provides a catalyst and a preparation method and application thereof, the catalyst has a structure as shown in a formula 1, GaxCe1-xO2, x is more than 0 and less than 1, and Ga < 3 + > is added into crystal lattices of CeO2 to form spherical particles with a porous structure. According to the invention, Ga < 3 + > is added into crystal lattices of CeO2 to form spherical particles with a porous structure, so that the adsorption capacity of the catalyst is improved. The spherical cerium oxide carrier has a relatively large specific surface area and relatively high static oxygen storage capacity, and has a relatively wide static operation window. By adding CeO2 into Ga, the interaction between the carrier and Ga < 3 + > is optimized, a strong interaction interface between Ga / Ce is constructed, the high-temperature stability and activity of the catalyst are improved, and the catalytic efficiency is improved by using remarkable micro-nano structure control.

Description

Technical Field

[0001] This invention belongs to the field of automotive exhaust purification catalyst technology, and particularly relates to a catalyst, its preparation method and application. Background Technology

[0002] In recent years, vehicle exhaust pollution has become an increasingly serious problem, posing a significant threat to air pollution, particularly the control of gasoline vehicle exhaust, which has become increasingly difficult. Three-way catalytic converters (TWCs) are currently the most effective end-of-pipe control method for purifying gaseous pollutants from gasoline vehicle exhaust. They can simultaneously reduce CO and NOx near the stoichiometric air-fuel ratio. x And HCs are converted into non-toxic and harmless CO2, H2O and N2. However, existing three-way catalysts use precious metals as the catalyst body, making it difficult to reduce costs.

[0003] In addition, cerium-zirconium composite oxides in metal catalytic material systems have been widely studied and applied in three-way catalysts due to their excellent redox performance and oxygen storage and release performance. However, the morphology of cerium-zirconium composite oxide catalysts is uncontrollable after modification, resulting in low catalytic performance. Summary of the Invention

[0004] This application provides a catalyst, its preparation method, and its application, aiming to improve the low catalytic performance of existing cerium-zirconium-based composite oxide catalysts.

[0005] In a first aspect, this application provides a catalyst having the structure shown in Formula 1. Ga x Ce 1-x O2, Formula 1, Where 0 < x < 1, Ga 3+ It is added to the CeO2 lattice to form spherical particles with a porous structure.

[0006] In this application, Ga 3+ Adding cerium oxide (CeO2) to the CeO2 lattice forms porous spherical particles, improving the catalyst's adsorption capacity. The spherical CeO2 support exhibits a large specific surface area and high static oxygen storage capacity, possessing a relatively wide static operating window. The addition of Ga to CeO2... 3+ Optimize the carrier and Ga 3+ The interaction between them constructs a strong interaction interface between Ga and Ce, allowing CeO2 to be incorporated into Ga. 3+ Subsequently, spherical particles with porous structures are formed, enhancing the catalyst's high-temperature stability and activity. The micro-nano structure of these spherical particles is utilized to control catalytic efficiency and performance. This catalyst is a non-precious metal catalyst, thus reducing costs.

[0007] Optionally, 0.02 ≤ x ≤ 0.22. In this case, the Ga in the catalyst... 3+ The added molar percentage is 2%-22%, and the spherical particle morphology of the catalyst varies with Ga. 3+ With the increase in the amount added, the spherical structure with uniformly distributed gaps on the surface is transformed into porous broccoli-shaped microspheres, which makes the catalyst exhibit a larger specific surface area and a higher static oxygen storage capacity, and has a relatively wide static operating window.

[0008] Optionally, the spherical particles satisfy at least one of the following conditions: The spherical microparticles have a porosity of 30%-50%, providing channels for vehicle exhaust gas to diffuse through the pores to the active sites of the catalyst, reducing diffusion resistance and preventing a decrease in conversion efficiency due to limited mass transfer. However, if the porosity is too high, the catalyst skeleton structure will be loose, the mechanical strength will decrease, and it will be easily broken due to vibration, resulting in the loss of active components. The specific surface area of ​​the spherical microparticles is 80-150 m². 2 / g; Spherical microparticles have a higher specific surface area, which can provide more anchoring points, making the Ga element more uniformly dispersed, while increasing the exposed area of ​​the oxygen storage material and increasing the number of active centers per unit mass of catalyst.

[0009] The static oxygen storage capacity of the spherical microparticles is 250-400 μmol / g. This oxygen storage capacity range ensures that the catalyst can efficiently convert CO, HC, and NOx pollutants over a wide air-fuel ratio range, thus broadening the activity window.

[0010] Spherical microparticles that meet the above conditions can regulate reactant mass transfer, active site utilization, and reaction condition adaptability through synergistic effects, thereby enabling the catalyst of this application to have high high-temperature stability and catalytic activity.

[0011] Secondly, this application provides a method for preparing a catalyst as described in any of the preceding claims, comprising the following steps: Ga and cerium sources are obtained according to the molar ratio of Ga to Ce in Formula 1. The gallium and cerium sources are dissolved in water to prepare a solution containing Ce. 3+ and Ga 3+ A mixed solution; A reducing agent and an alkaline solution are added to the mixed solution to obtain a gel precursor solution, and the gel precursor solution is dispersed to obtain a gel; The gel was heated and dried to obtain a catalyst precursor; The catalyst precursor was calcined to obtain a catalyst with the structure shown in Formula 1.

[0012] The catalyst preparation method of the present invention controls the Ga 3+By adjusting the addition ratio and gelation conditions, a porous, spherical, particulate catalyst is formed, allowing for controllable catalyst morphology. When used in gasoline engine exhaust treatment, this catalyst improves high-temperature stability while reducing the amount of precious metals required.

[0013] Optionally, Ce in the mixed solution 3+ and Ga 3+ The sum of their concentrations is 0.01-0.10 mol / L. This is achieved by adjusting the Ce concentration. 3+ and Ga 3+ The total concentration of Ce is controlled, thereby regulating the ionic strength of the mixed solution and further controlling the morphology of the final catalyst. When the total concentration is too high, Ce... 3+ and Ga 3+ During calcination, "co-agglomeration" easily occurs, forming large-sized composite oxide particles, which reduces the catalyst's specific surface area and porosity, affecting the diffusion of reactants in the exhaust gas. When the total concentration is too low, Ce... 3+ and Ga 3+ Insufficient total oxygen content weakens the catalyst's oxygen storage capacity and inhibits catalytic activity.

[0014] Optionally, the gallium source is selected from at least one of Ga(NO3)3, GaCl3, and Ga2(SO4)3; And / or, the cerium source is selected from at least one of Ce(NO3)3·6H2O, CeCl3 and Ce2(SO4)3; And / or, the reducing agent is selected from D-(+)-glucose and acrylic acid in a molar ratio of 1:(1-1.5); And / or, the alkaline solution is selected from at least one of ammonia, NaOH and KOH.

[0015] By selecting the aforementioned gallium and cerium sources, their uniform dispersion in the mixed solution is ensured, thereby guaranteeing a uniform distribution of Ce and Ga in the gel. The reduction rate of Ga ions is controlled by selecting the aforementioned reducing agents, and both glucose and acrylic acid can react with Ce. 3+ and Ga 3+ Forming coordination bonds slows down the migration and aggregation rate, resulting in more uniform dispersion of active components, stabilizing the nanoparticles generated during gelation, and preventing particle sintering during calcination. The pH of the gel precursor solution is adjusted using the aforementioned alkaline solution to regulate the gel formation rate and ensure Ce... 3+ and Ga 3+ It is evenly distributed in the gel.

[0016] Optionally, the ratio of the total amount of Ce and Ga to the amount of acrylic acid is 1:(2-5). By adjusting the ratio of the total amount of Ce and Ga to the amount of acrylic acid within the above range, it is ensured that the acrylic acid can react with Ce.3+ and Ga 3+ It forms coordination bonds, inhibits excessive aggregation of metal ions, and improves dispersion.

[0017] Optionally, the pH of the gel precursor solution is 8-10. By adjusting the pH of the gel precursor solution, Ce... 3+ and Ga 3+ It can form a gel after the addition of a reducing agent.

[0018] Optionally, the calcination conditions are calcination at 300-550℃ for 3-5 hours. By calcining the catalyst precursor within the above temperature range, the organic matter in the catalyst precursor is completely decomposed into gas and escapes, thereby forming a porous structure and obtaining a catalyst with a stable crystal phase structure.

[0019] Thirdly, this application provides the application of a catalyst as described in any of the preceding claims in the purification of gasoline vehicle exhaust gases. Alternatively, it provides the application of a catalyst prepared by any of the preceding methods in the purification of gasoline vehicle exhaust gases, thereby reducing exhaust gas treatment costs and improving exhaust gas treatment efficiency. Attached Figure Description

[0020] Figure 1 These are the SEM microstructures of Examples 1-4 and Comparative Example 1 of the present invention; Figure 2 The XRD patterns of Embodiments 1, 2 and Comparative Example 1 of the present invention are shown below; Figure 3 The Raman spectra are those of Examples 1, 2 and Comparative Example 1 of the present invention. Detailed Implementation

[0021] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] One embodiment of this application provides a catalyst having the structure shown in Formula 1. Ga x Ce 1-x O2 type 1, Where 0 < x < 1, Ga 3+ It is added to the CeO2 lattice to form spherical particles with a porous structure.

[0023] In this invention, Ga 3+Adding cerium oxide to the CeO2 lattice forms porous spherical particles, improving the catalyst's adsorption capacity. The spherical cerium oxide support exhibits a large specific surface area and high static oxygen storage capacity, resulting in a relatively wide static operating window. The method of incorporating Ga into CeO2 optimizes the relationship between the support and Ga. 3+ The interaction between them constructs a strong interaction interface between Ga and Ce, allowing CeO2 to be incorporated into Ga. 3+ Subsequently, spherical particles with porous structures are formed, enhancing the catalyst's high-temperature stability and activity. The micro-nano structure of these spherical particles is utilized to control catalytic efficiency and performance. This catalyst is a non-precious metal catalyst, thus reducing costs.

[0024] By using smaller Ga 3+ The addition of 0.062 nm to the larger CeO2 (0.092 nm) lattice reduces the CeO2 lattice constant, decreases the interplanar spacing within the unit cell, and increases the compressive strain. For example... Figure 1 As shown, with Ga 3+ With increasing concentration, the morphology of the spherical particles changes from a flower-like structure with a width of 5 μm to a broccoli-shaped microsphere with a diameter of 20 μm due to compressive strain. The spherical particles are loose and have high porosity, which improves the adsorption capacity of the catalyst, further reduces the resistance of the exhaust gas to diffusion to the active site, and improves the catalytic performance.

[0025] like Figure 2 As shown, when the Ga content increases from 0% to 1% and 2%, the magnified XRD patterns show a gradual broadening of the (111) peak. Furthermore, the pattern shifts to higher angles due to the presence of Ce in the lattice. 4+ Be Ga 3+ The alternative proof further confirms that the introduction of smaller diameter Ga into the unit cell... 3+ This can lead to a decrease in the lattice constant, a decrease in the interplanar spacing within the unit cell, and an increase in compressive strain, resulting in the formation of a porous structure in the spherical particles, which has a higher catalytic efficiency.

[0026] In one embodiment, 0.02 ≤ x ≤ 0.22. In this case, Ga in the catalyst... 3+ The added molar percentage is 2%-22%, such as Figure 1 and Figure 2 As shown, the spherical particle morphology of the catalyst varies with Ga 3+ With the increase in the amount added, the spherical structure with uniformly distributed gaps on the surface is transformed into porous broccoli-shaped microspheres, which makes the catalyst exhibit a larger specific surface area and a higher static oxygen storage capacity, and has a relatively wide static operating window.

[0027] Specifically, x includes, but is not limited to, 0.02, 0.05, 0.07, 0.09, 0.11, 0.13, 0.15, 0.17, 0.19, or 0.22.

[0028] In a preferred embodiment, to ensure that the catalyst has a large specific surface area and a high static oxygen storage capacity, the Ga content in Formula 1 is preferably 1%-2%.

[0029] In some embodiments, the spherical microparticles satisfy at least one of the following conditions: The spherical microparticles have a porosity of 30%-50%, providing a channel for vehicle exhaust gas to diffuse through the pores to the active sites of the catalyst, reducing diffusion resistance and preventing a decrease in conversion efficiency due to limited mass transfer. However, if the porosity is too high, the catalyst skeleton structure will be loose, the mechanical strength will decrease, and it will be easily broken due to vibration, resulting in the loss of active components.

[0030] Specifically, the porosity of the spherical microparticles includes, but is not limited to, 30%, 33%, 36%, 39%, 42%, 45%, 48%, or 50%.

[0031] The specific surface area of ​​the spherical microparticles is 80-150 m². 2 / g; Spherical microparticles have a higher specific surface area, which can provide more anchoring points, making the Ga element more uniformly dispersed, while increasing the exposed area of ​​the oxygen storage material and increasing the number of active centers per unit mass of catalyst.

[0032] Specifically, the specific surface area of ​​spherical particles includes, but is not limited to, 80 m². 2 / g、85 m 2 / g、90 m 2 / g、95 m 2 / g, 100 m 2 / g, 105 m 2 / g、110 m 2 / g、115 m 2 / g、120 m 2 / g、125 m 2 / g、130 m 2 / g、135 m 2 / g、140 m 2 / g、145 m 2 / g or 150 m 2 / g.

[0033] The static oxygen storage capacity of the spherical microparticles is 250-400 μmol / g. This range of oxygen storage capacity ensures that the catalyst can efficiently convert CO, HC, and NOx pollutants over a wide air-fuel ratio range, thus broadening the activity window. The static oxygen storage capacity of the spherical microparticles includes, but is not limited to, 250 μmol / g, 260 μmol / g, 270 μmol / g, 280 μmol / g, 290 μmol / g, 300 μmol / g, 310 μmol / g, 320 μmol / g, 330 μmol / g, 340 μmol / g, 350 μmol / g, 360 μmol / g, 370 μmol / g, 380 μmol / g, 390 μmol / g, or 400 μmol / g.

[0034] Spherical microparticles that meet the above conditions can regulate reactant mass transfer, active site utilization, and reaction condition adaptability through synergistic effects, thereby enabling the catalyst of this application to have high high-temperature stability and catalytic activity.

[0035] Secondly, one embodiment of this application provides a method for preparing a catalyst as described in any of the preceding claims, comprising the following steps: Ga and cerium sources are obtained according to the molar ratio of Ga to Ce in Formula 1. The gallium and cerium sources are dissolved in water to prepare a solution containing Ce. 3+ and Ga 3+ A mixed solution; A reducing agent and an alkaline solution are added to the mixed solution to obtain a gel precursor solution, and the gel precursor solution is dispersed to obtain a gel; The gel was heated and dried to obtain a catalyst precursor. Specifically, the gel was transferred to an autoclave and heated at 180°C for 72 hours in a convection oven. The precipitate was then filtered, washed twice with deionized water and ethanol, and then dried in an oven at 70°C for 3 hours.

[0036] The catalyst precursor was calcined to obtain a catalyst with the structure shown in Formula 1.

[0037] In this embodiment, by adjusting Ga 3+ By adjusting the addition ratio and gelation conditions, a porous, spherical, particulate catalyst is formed, allowing for controllable catalyst morphology. When used in gasoline engine exhaust treatment, this catalyst improves high-temperature stability while reducing the amount of precious metals required.

[0038] In some embodiments, Ce in the mixed solution 3+ and Ga 3+ The sum of their concentrations is 0.01-0.10 mol / L. This is achieved by adjusting the Ce concentration. 3+ and Ga 3+The total concentration of Ce is controlled, thereby regulating the ionic strength of the mixed solution and further controlling the morphology of the final catalyst. When the total concentration is too high, Ce... 3+ and Ga 3+ During calcination, "co-agglomeration" easily occurs, forming large-sized composite oxide particles, which reduces the catalyst's specific surface area and porosity, affecting the diffusion of reactants in the exhaust gas. When the total concentration is too low, Ce... 3+ and Ga 3+ Insufficient total oxygen content weakens the catalyst's oxygen storage capacity and inhibits catalytic activity.

[0039] In some embodiments, the gallium source is selected from at least one of Ga(NO3)3, GaCl3, and Ga2(SO4)3; And / or, the cerium source is selected from at least one of Ce(NO3)3·6H2O, CeCl3 and Ce2(SO4)3; And / or, the reducing agent is selected from D-(+)-glucose and acrylic acid in a molar ratio of 1:(1-1.5); specifically, the molar ratio of D-(+)-glucose and acrylic acid includes, but is not limited to, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5.

[0040] And / or, the alkaline solution is selected from at least one of ammonia, NaOH and KOH.

[0041] By selecting the aforementioned gallium and cerium sources, their uniform dispersion in the mixed solution is ensured, thereby guaranteeing a uniform distribution of Ce and Ga in the gel. The reduction rate of Ga ions is controlled by selecting the aforementioned reducing agents, and both glucose and acrylic acid can react with Ce. 3+ and Ga 3+ Forming coordination bonds slows down the migration and aggregation rate, resulting in more uniform dispersion of active components, stabilizing the nanoparticles generated during gelation, and preventing particle sintering during calcination. The pH of the gel precursor solution is adjusted using the aforementioned alkaline solution to regulate the gel formation rate and ensure Ce... 3+ and Ga 3+ It is evenly distributed in the gel.

[0042] In a preferred embodiment, the gallium source is selected from Ga(NO3)3. By selecting the above-mentioned gallium source, the anions of the gallium source volatilize during the calcination process, ensuring that there are no impurity residues after the catalyst precursor is calcined. The cerium source is selected from Ce(NO3)3·6H2O, and the amount of Ga(NO3)3 accounts for 1% to 10% of the total amount of Ce(NO3)3·6H2O and Ga(NO3)3, to ensure that Ga 3+ It is added to the CeO2 lattice to form spherical particles with a porous structure.

[0043] The molar ratio of D-(+)-glucose to acrylic acid is 1:1.5. The reducing properties of the reducing agent are controlled by adjusting the amounts of D-(+)-glucose and acrylic acid.

[0044] In some embodiments, the ratio of the total amount of Ce and Ga to the amount of acrylic acid is 1:(2-5). By adjusting the ratio of the total amount of Ce and Ga to the amount of acrylic acid within the above range, it is ensured that the acrylic acid can react with Ce. 3+ and Ga 3+ It forms coordination bonds, inhibits excessive aggregation of metal ions, and improves dispersion.

[0045] Specifically, the ratio of the total amount of Ce and Ga to the amount of acrylic acid is, but is not limited to, 1:2, 1:3, 1:4 or 1:5.

[0046] In some embodiments, the pH of the gel precursor solution is 8-10. Specifically, the pH of the gel precursor solution is 9. By adjusting the pH of the gel precursor solution, Ce... 3+ and Ga 3+ It can form a gel after the addition of a reducing agent.

[0047] In some embodiments, the calcination conditions are calcination at 300-550°C for 3-5 hours. By calcining the catalyst precursor within the above temperature range, the organic matter in the catalyst precursor is completely decomposed into gas and released, thereby forming a porous structure and obtaining a catalyst with a stable crystal phase structure.

[0048] Specifically, the roasting temperature includes, but is not limited to, 300℃, 320℃, 340℃, 360℃, 380℃, 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, 520℃, 540℃, or 550℃. The roasting time includes, but is not limited to, 3h, 4h, or 5h.

[0049] Thirdly, one embodiment of this application provides the application of a catalyst as described in any of the preceding claims in the purification of gasoline vehicle exhaust. Alternatively, it provides the application of a catalyst prepared by any of the above methods in the purification of gasoline vehicle exhaust, thereby reducing exhaust treatment costs and improving exhaust treatment efficiency.

[0050] The present invention will be further illustrated by the following examples.

[0051] Example 1 This embodiment illustrates the catalyst and its preparation method disclosed in this invention, and includes the following steps: (1) According to cerium gallium oxide Ga 0.01 Ce 0.99The molar ratio of Ga to Ce in O2 was used to obtain the corresponding cerium source Ce(NO3)3·6H2O and gallium source Ga(NO3)3·nH2O; the molar percentage of Ga was 1%.

[0052] (2) Dissolve the gallium source and the cerium source separately in deionized water to form a mixed solution; (3) Add D-(+)-glucose and acrylic acid in a ratio of 1:1.5 to the mixed solution obtained in step (2), and the ratio of the total amount of Ce and Ga to the amount of acrylic acid is 1:3. (4) After stirring for 10 minutes, add ammonia solution to adjust the pH to 9, and continue stirring for 30 minutes to obtain a gel; (5) The obtained gel was transferred to an autoclave and heated at 180°C for 72 hours in a convection oven. After precipitation, it was filtered and washed twice with deionized water and ethanol, and then dried in an oven at 70°C for 3 hours. (6) Calcination at 450℃ in a muffle furnace for 4 hours yielded Ga 0.01 Ce 0.99 O2 catalyst.

[0053] Example 2 Example 2 is used to illustrate the catalyst and its preparation method disclosed in this invention, including most of the operation steps in Example 1 above, except that: x is 0.02 and the molar percentage of Ga is 2%.

[0054] Example 3 Example 3 is used to illustrate the catalyst and its preparation method disclosed in this invention, including most of the operation steps in Example 1 above, except that: x is 0.05 and the molar percentage of Ga is 5%.

[0055] Example 4 Example 4 illustrates the catalyst and its preparation method disclosed in this invention, including most of the operation steps in Example 1 above, except that: x is 0.1 and the molar percentage of Ga is 10%.

[0056] Example 5 Example 5 illustrates the catalyst and its preparation method disclosed in this invention, including most of the operation steps in Example 1 above, except that: x is 0.9 and the molar percentage of Ga is 90%.

[0057] Example 6 Example 6 illustrates the catalyst and its preparation method disclosed in this invention, including most of the operating steps in Example 1 above, except that the pH is 8.

[0058] Example 7 Example 7 illustrates the catalyst and its preparation method disclosed in this invention, including most of the operation steps in Example 1 above, except that the pH is 10.

[0059] Example 8 Example 8 illustrates the catalyst and its preparation method disclosed in this invention, including most of the operation steps in Example 1 above, except that the pH is 9.5.

[0060] Example 9 Example 9 illustrates the catalyst and its preparation method disclosed in this invention, including most of the operation steps in Example 1 above, except that the calcination temperature is 550°C.

[0061] Comparative Example 1 Comparative Example 1 is used to illustrate the catalyst and its preparation method disclosed in this invention, including most of the operation steps in Example 1, except that x is 0.

[0062] Comparative Example 2 The catalyst is an alumina-supported cerium-zirconium solid solution composite oxide of Angxing's novel carbon material.

[0063] Performance testing The catalysts prepared in the above examples and comparative examples were subjected to activity evaluation experiments. The specific surface area and static oxygen storage capacity of the catalysts prepared in the examples and comparative examples were tested. The specific surface area was tested using the N2 physical adsorption method. Some aged samples were first reduced with hydrogen at 550℃, and then O2- pulsed tests were performed at 400℃ to obtain the static oxygen storage capacity and Ga. x Ce 1-x The x value in O2 was determined by X-ray fluorescence spectroscopy.

[0064] The catalyst activity was tested using a laboratory-assembled fixed-bed continuous flow reactor. The catalyst was immobilized in the reactor, and the gas hourly space velocity (GHSV) was controlled at 50,000 h⁻¹. -1 The composition of the simulated exhaust gas is shown in Table 1. Before the activity test, the catalyst was pretreated in a simulated exhaust gas atmosphere at 550℃ for 1 hour, and then cooled to below T10 (the temperature at which the pollutant conversion rate is 10%). Subsequently, under continuous heating conditions, the concentration of each pollutant was detected to decrease at the analyzer outlet. The T50 and T90 (the temperatures at which the pollutant conversion rates are 50% and 90%) of each pollutant were recorded to evaluate the catalyst activity. The test results are shown in Table 2.

[0065] Table 1 Simulated exhaust gas conditions Table 2 As can be seen from the test results of Examples 1-5 and Comparative Example 1 in Table 2, when x=0.05, the specific surface area and oxygen storage capacity of the catalyst reach their peak values, and T50 / T90 is the lowest, which further proves that the appropriate addition of Ga can optimize the oxygen vacancy concentration and lattice defects of CeO2.

[0066] The test results of Examples 1 and 6-8 show that the catalyst has the largest specific surface area and the most uniform structure at pH=9. Increasing or decreasing the pH will cause the specific surface area of ​​the catalyst to decrease by about 10-15%, which will affect the high temperature stability and activity of the catalyst.

[0067] The test results of Examples 1 and 9 show that the crystallinity and porosity of the catalyst are optimally balanced at a calcination temperature of 450°C. When the temperature is increased to 550°C, the specific surface area decreases by more than 20%, which affects the high-temperature stability and activity of the catalyst.

[0068] As can be seen from the test results of Examples 1-9 and Comparative Example 2, the specific surface area and oxygen storage capacity of the cerium-zirconium composite oxide are moderate, but its catalytic activity is lower than that of the Ga-CeO2 system of this application.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0070] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0071] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A catalyst, characterized in that, It has the structure shown in Equation 1. Ga x Ce 1-x O2, Formula 1 Where 0 < x < 1, Ga 3+ It is added to the CeO2 lattice to form spherical particles with a porous structure.

2. The catalyst according to claim 1, characterized in that, 0.02≤x≤0.22。 3. The catalyst according to claim 1, characterized in that, The spherical particles satisfy at least one of the following conditions: The porosity of the spherical microparticles is 30%-50%; The specific surface area of ​​the spherical microparticles is 80-150 m². 2 / g; The static oxygen storage capacity of the spherical microparticles is 250-400 μmol / g.

4. The method for preparing the catalyst according to any one of claims 1-3, characterized in that, Includes the following steps: Ga and cerium sources are obtained according to the molar ratio of Ga to Ce in Formula 1. The gallium and cerium sources are dissolved in water to prepare a solution containing Ce. 3+ and Ga 3+ A mixed solution; A reducing agent and an alkaline solution are added to the mixed solution to obtain a gel precursor solution, and the gel precursor solution is dispersed to obtain a gel; The gel was heated and dried to obtain a catalyst precursor; The catalyst precursor was calcined to obtain a catalyst with the structure shown in Formula 1.

5. The method for preparing the catalyst according to claim 4, characterized in that, Ce in the mixed solution 3+ and Ga 3+ The sum of their concentrations is 0.01-0.10 mol / L.

6. The method for preparing the catalyst according to claim 4, characterized in that, The gallium source is selected from at least one of Ga(NO3)3, GaCl3 and Ga2(SO4)3; And / or, the cerium source is selected from at least one of Ce(NO3)3·6H2O, CeCl3 and Ce2(SO4)3; And / or, the reducing agent is selected from D-(+)-glucose and acrylic acid in a molar ratio of 1:(1-1.5); And / or, the alkaline solution is selected from at least one of ammonia, NaOH and KOH.

7. The method for preparing the catalyst according to claim 6, characterized in that, The ratio of the total amount of Ce and Ga to the amount of acrylic acid is 1:(2-5).

8. The method for preparing the catalyst according to claim 4, characterized in that, The pH of the gel precursor solution is 8-10.

9. The method for preparing the catalyst according to claim 4, characterized in that, The calcination conditions are 300-550℃ for 3-5 hours.

10. The application of the catalyst according to any one of claims 1-3 in the purification of gasoline vehicle exhaust, or the application of the catalyst prepared by the preparation method according to any one of claims 4-9 in the purification of gasoline vehicle exhaust.

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