Preparation method of high-performance cerium-based denitration catalyst modified by layered compound HTiNbO5

Abstract

The present invention discloses a preparation method of a high-performance cerium-based denitration catalyst modified by a layered compound HTiNbO5. A certain amount of CeO2 and a solid acid HTiNbO5 are uniformly mixed by mechanical grinding, calcined at 500 °C for 5 h in a flowing air atmosphere, and cooled to room temperature to obtain a cerium dioxide-based catalyst supported on HTiNbO5. The advantages of the present invention are as follows: the process is simple and the preparation cost is low. Solvents are not required during the preparation process, and it has the characteristics of high yield and environmental friendliness, and is suitable for large-scale industrial production. In addition, after mechanical grinding, the order degree of the catalyst structure is damaged, and the surface lattice defects of cerium dioxide increase, which is beneficial to the formation of oxygen vacancies, preventing the adhesion and agglomeration of the catalyst, thereby improving the catalytic activity. At the same time, taking advantage of the rich protonic acid of HTiNbO5, it can improve the acidity of CeO2, which is beneficial to the adsorption of NH3 on the surface of the catalyst during the selective catalytic reduction of nitrogen oxides by ammonia. The conversion rate of NOx of this catalyst reaches more than 80% in the range of 250-400 °C, making up for the disadvantage of the weak acidity of pure CeO2 in NH3-SCR.

Description

Technical Field

[0001] The present invention belongs to the technical field of treatment of atmospheric nitrogen oxides pollution, and particularly relates to a preparation method of a high-performance cerium-based denitration catalyst modified by a layered compound HTiNbO5. Background Art

[0002] Nitrogen oxides (NOx) mainly come from the flue gas emitted by factories and the exhaust gas emitted by motor vehicles. It is one of the main pollutants causing acid rain, photochemical smog, ozone holes and eutrophication of surface water. In addition, it seriously damages the ecological environment and human health, so it is the focus of current environmental protection research. In this case, selective catalytic reduction (SCR) is a currently widely used flue gas denitration (deNOx) technology. The most common commercial denitration catalyst is V2O5-WO3 / TiO2, and its operating temperature is 330 - 400 °C. However, vanadium-based catalysts have some disadvantages, such as a narrow operating temperature window, poor N2 selectivity, a high conversion rate of SO2 to SO3, and the biological toxicity of vanadium species, which limits the wide application of V2O5-WO3 / TiO2 catalysts in industry. Therefore, the development of new NH3-SCR catalysts with high efficiency, stability and environmental friendliness has become a hot topic for many researchers in this field.

[0003] In the NH3-SCR reaction, the redox property and surface acidity of the catalyst are decisive factors affecting the catalytic activity. Since the surface atoms of CeO2 are easier to change than Ce 3+ / Ce 4+ it has good redox performance and a high oxygen storage / release capacity, so it has been widely studied in NH3-SCR. However, the weak surface acidity of pure CeO2 leads to unsatisfactory catalytic performance in NH3-SCR. The structure of the layered compound HTiNbO5 is composed of TiO6 octahedrons and NbO6 octahedrons through edge-sharing and corner-sharing to form a two-dimensional anion sheet layer, H +It exists as a compensating ion between the layers of the layered compound. Due to the special layered structure and abundant protonic acid of HTiNbO5, it is currently widely used in the field of photocatalysis. First, taking advantage of its abundant protonic acid, the CeO2 catalyst is modified to increase its surface acidity and improve its denitrification activity. In addition, the method of mechanical grinding and calcination not only has simple operation and reduces the preparation cost, but also destroys the structural order of the catalyst and increases the concentration of oxygen vacancies on the surface. In addition, CeO2 itself has good redox properties, and the simple mixing and mechanical grinding method will not cause obvious interaction between HTiNbO5 and CeO2, and has little effect on the redox properties of the cerium-based catalyst, which to a certain extent avoids the weakening of this modification promotion effect (reduction of redox properties) or the reduction of activity and selectivity due to excessive oxidation at medium and high temperatures (improvement of redox properties). Considering the optimization of the structure and properties of the catalyst after the above modifications, the denitrification activity of the catalyst is greatly improved.

[0004] The research on NH3-SCR catalysts involves traditional medium and high temperature denitrification and new low temperature denitrification, and cerium-based catalysts have shown good denitrification activity under laboratory conditions, but there is still a certain distance from the industrial application level. Therefore, based on the above problems and the previous research work, the present invention conducts basic application research on cerium-based catalysts in aspects such as adding additives and optimizing the preparation method, hoping to achieve industrial application. Summary of the Invention

[0005] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Simplifications or omissions may be made in this part, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract, and the title, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0006] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a preparation method for a high-performance cerium-based denitrification catalyst modified by a simple and inexpensive layered compound HTiNbO5.

[0008] To solve the above technical problems, the present invention provides the following technical solution: A preparation method for a high-performance cerium-based denitrification catalyst modified by a layered compound HTiNbO5, characterized in that it includes:

[0009] Cerium nitrate hexahydrate is ground into a precursor powder without particle sense and then calcined and activated. After the calcination is completed, it is cooled with the furnace to obtain a pure CeO2 catalyst powder;

[0010] Mix HTiNbO5 and CeO2, grind them until there are no particles and the mixture is homogeneous, then calcine and activate. After the calcination is completed, keep the temperature and then cool with the furnace to obtain the HTiNbO5 / CeO2 catalyst powder.

[0011] As a preferred embodiment of the preparation method of the present invention, when the cerium nitrate hexahydrate is 60 g, the grinding time is 20 min and there is no particle feeling.

[0012] As a preferred embodiment of the preparation method of the present invention, the calcination conditions are all in a flowing air atmosphere.

[0013] As a preferred embodiment of the preparation method of the present invention, the heating rate of the calcination conditions is 2 °C / min, rising from room temperature to 500 °C.

[0014] As a preferred embodiment of the preparation method of the present invention, the heat preservation time is 5 h.

[0015] As a preferred embodiment of the preparation method of the present invention, the cooling method is natural cooling.

[0016] As a preferred embodiment of the preparation method of the present invention, the mass ratio of HTiNbO5 to CeO2 in the HTiNbO5 / CeO2 catalyst is 1:19 - 3:17.

[0017] As a preferred embodiment of the preparation method of the present invention, the HTiNbO5 accounts for 5 wt% - 15 wt% of the total mass of the catalyst.

[0018] As a preferred embodiment of the preparation method of the present invention, the HTiNbO5 is a solid acid promoter.

[0019] Another object of the present invention is to overcome the deficiencies in the prior art and provide a product prepared by a preparation method of a high-performance cerium-based denitration catalyst modified by a layered compound HTiNbO5.

[0020] Another object of the present invention is to overcome the deficiencies in the prior art and provide an application of a simple and inexpensive high-performance cerium-based denitration catalyst modified by a layered compound HTiNbO5 in a denitration catalyst.

[0021] Advantages of the present invention:

[0022] (1) A preparation method of a high-performance cerium-based denitration catalyst modified by HTiNbO5 proposed by the present invention does not require the use of solvents during the preparation process, which can effectively avoid the loss of active components and achieve high yield. In addition, the preparation process of this method is simple, low-cost, and environmentally friendly, and is suitable for large-scale industrial production. At the same time, the mechanical grinding method will destroy the order of the surface structure of cerium dioxide, increase the lattice defects on the catalyst surface, be conducive to the formation of oxygen vacancies, improve the catalyst activity, and also prevent the catalyst from agglomerating and adhering.

[0023] (2) A preparation method of a high-performance cerium-based denitration catalyst modified by HTiNbO5 proposed by the present invention has little influence on the redox property of the cerium dioxide catalyst by HTiNbO5 modification, which ensures that the HTiNbO5 / CeO2 catalyst will not reduce its activity due to the change of redox property in the medium and high temperature range.

[0024] (3) A preparation method of a high-performance cerium-based denitration catalyst modified by HTiNbO5 proposed by the present invention uses HTiNbO5 as a solid acid promoter, which can improve the acidity of the catalyst and make up for the disadvantage of weak acidity of pure CeO2 in the selective catalytic reduction of nitrogen oxides by ammonia (NH3-SCR) reaction, and is conducive to improving the reaction rate and denitration efficiency.

[0025] (4) A preparation method of a high-performance cerium-based denitration catalyst modified by HTiNbO5 proposed by the present invention, compared with the existing cerium-based catalysts modified by acidic promoters, the nitrogen oxide conversion rate of this catalyst reaches more than 80% in the range of 250-400 °C, significantly improving the denitration efficiency and reducing the risk of secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. Among them:

[0027] The catalysts in the following figures are all made by mechanical grinding and then calcined at 500 °C.

[0028] Figure 1 It is a schematic diagram of the denitration efficiency of three 10wt% HTiNbO5 / CeO2 catalysts and pure CeO2 catalyst prepared by mechanical grinding method, impregnation method and hydrothermal method.

[0029] Figure 2 It is a schematic diagram of the denitration efficiency of three catalysts prepared by mechanical grinding method and calcined at different temperature conditions and pure CeO2 catalyst.

[0030] Figure 3 XRD results of high-performance cerium-based catalysts modified by HTiNbO5 with different ratios of HTiNbO5 and CeO2.

[0031] Figure 4 NOx conversion results of high-performance cerium-based catalysts modified by HTiNbO5 with different ratios of HTiNbO5 and CeO2.

[0032] Figure 5 H2-TPR results of high-performance cerium-based catalysts modified by HTiNbO5 with different ratios of HTiNbO5 and CeO2.

[0033] Figure 6 NH3-TPD results of high-performance cerium-based catalysts modified by HTiNbO5 with different ratios of HTiNbO5 and CeO2. Detailed implementation manners

[0034] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following describes the detailed implementation manners of the present invention in combination with the embodiments of the specification.

[0035] Many specific details are set forth in the following description to facilitate a thorough understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0036] Secondly, the so-called "one embodiment" or "embodiment" refers to a specific feature, structure, or characteristic that can be included in at least one implementation manner of the present invention. The "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that mutually excludes other embodiments.

[0037] Example 1

[0038] Preparation of 10wt% HTiNbO5 / CeO2 catalyst (mechanical grinding method):

[0039] Weigh 0.2 g of HTiNbO5 and 1.8 g of cerium dioxide. Grind the above mixture in an agate mortar for 20 minutes until fully mixed, then spread it flat in a crucible, and then put it into a muffle furnace and calcine it in a flowing air atmosphere. The calcination temperature of the muffle furnace is 500 °C, the heating rate is 2 °C / min, and the calcination time is 5 h. After cooling to room temperature, 10wt% HTiNbO5 / CeO2 catalyst powder is obtained, denoted as 10HT / CeO2 (JX). Press the prepared catalyst into tablets through a tablet press, and sieve it to retain particles with a size of 40-60 mesh for further testing.

[0040] Comparative Example 1

[0041] Prepare the CeO2 catalyst:

[0042] Weigh 60 g of cerium nitrate hexahydrate, grind it in an agate mortar for 20 minutes until there is no sense of granule, then spread it flat in a crucible, and then put it into a muffle furnace and calcine it in a flowing air atmosphere. The calcination temperature of the muffle furnace is 500 °C, the heating rate is 2 °C / min, the calcination time is 5 h, and after cooling to room temperature, the CeO2 catalyst powder is obtained. The prepared catalyst is pressed into tablets by a tablet press and sieved to a 40-60 mesh sieve for retention and waiting for testing.

[0043] Comparative Example 2

[0044] Prepare 10 wt% HTiNbO5 / CeO2 catalyst (impregnation method):

[0045] Weigh 0.2 g of HTiNbO5 and 1.8 g of cerium dioxide, add 20 mL of deionized water, stir for 30 min, evaporate to dryness in a water bath at 80 °C, put it into an oven and dry it at 110 °C for 12 h, then spread the above-obtained sample flat in a crucible, and then put it into a muffle furnace and calcine it in a flowing air atmosphere. The calcination temperature of the muffle furnace is 500 °C, the heating rate is 2 °C / min, the calcination time is 5 h, and after cooling to room temperature, the 10 wt% HTiNbO5 / CeO2 catalyst powder is obtained, denoted as 10HT / CeO2 (JZ). The prepared catalyst is pressed into tablets by a tablet press and sieved to a 40-60 mesh sieve for retention and waiting for testing.

[0046] Comparative Example 3

[0047] Prepare 10 wt% HTiNbO5 / CeO2 catalyst (hydrothermal method):

[0048] Weigh 0.2 g of HTiNbO5 and 1.8 g of cerium dioxide, add 20 mL of deionized water, stir for 30 min, pour the obtained solution into a reaction kettle, react at 110 °C for 5 h, then filter the reacted solution, then put the obtained filter cake into an oven and dry it for 12 h, and finally spread the above-obtained sample flat in a crucible, and then put it into a muffle furnace and calcine it in a flowing air atmosphere. The calcination temperature of the muffle furnace is 500 °C, the heating rate is 2 °C / min, the calcination time is 5 h, and after cooling to room temperature, the 10 wt% HTiNbO5 / CeO2 catalyst powder is obtained, denoted as 10HT / CeO2 (SR). The prepared catalyst is pressed into tablets by a tablet press and sieved to a 40-60 mesh sieve for retention and waiting for testing.

[0049] Perform catalyst activity tests on the catalysts obtained in Example 1 and Comparative Examples 1-3. The test method is as follows:

[0050] Catalyst Activity Test

[0051] Under steady state, the reaction gas components involved in the NH3-SCR reaction are NH3 = 500 ppm, NO = 500 ppm, O2 = 5 vol%, and N2 as the balance gas. The total gas flow rate is 100 mL / min (NH3 is 10 mL / min, NO is 10 mL / min, and O2 is 80 mL / min). The main process is as follows: First, accurately weigh 100 mg of the sample and load it into a quartz tube with an inner diameter of 5 mm, then place it in a heating furnace connected to a temperature-programmed device, and purge it in a high-purity nitrogen stream at 200 °C for 1 h. Then, turn on the reaction mixture gas, react at a space velocity ratio of 120,000 mL·g-1·h-1 at different temperatures for 15 min and collect the tail gas, and measure the nitrogen oxide concentration with an ECOM J2KN type flue gas analyzer. Finally, calculate the conversion rate of nitrogen oxides through the following formula:

[0052]

[0053] In the formula, [NO x in represents the inlet concentration of nitrogen oxides before the reaction, and [NO x out represents the tail gas concentration of nitrogen oxides after the reaction.

[0054] The test results are as Figure 1 shown. As can be seen from Figure 1 the figure, we found that as the loading amount of HTiNbO5 increases, the changing trends of the NOx conversion rates of the three catalysts are similar, that is, they gradually increase with the increase of temperature; however, overall, the catalyst prepared by the mechanical grinding method has the best denitrification effect. For example, at 250 °C, the NOx conversion rate of the 10HT / CeO2 (JX) catalyst is 81.3%, while those of 10HT / CeO2 (JZ) and 10HT / CeO2 (SR) are only 62% and 30%, significantly lower than the former. Therefore, among these three methods, the CeO2 catalyst modified by HTiNbO5 prepared by the mechanical grinding method has the best denitrification efficiency. Based on this result, we next choose the mechanical grinding method to prepare the catalyst and continue to optimize the preparation conditions by changing the calcination temperature during the preparation process.

[0055] Comparative Example 4

[0056] Prepare 10 wt% HTiNbO5 / CeO2 catalyst:

[0057] Except that the calcination temperature is 400 °C, the basic content of the preparation process is the same as that in Step 1 of Example 1, and the obtained sample is denoted as 10HT / CeO2 (400).

[0058] Comparative Example 5 ​​

[0059] Preparation of 10 wt% HTiNbO5 / CeO2 catalyst:

[0060] Except that the calcination temperature was 600 °C, the basic content of the preparation process was the same as that in Example 1, and the obtained sample was denoted as 10HT / CeO2(600).

[0061] The catalysts obtained in Example 2 and Comparative Examples 1, 4, and 5 were subjected to catalyst activity tests. The test scheme was the same as above, and the test results are as Figure 2 shown. From Figure 2 it can be seen that the NO x conversion rate values of all samples gradually increased with the increase of temperature, and the activity was higher than that of the pure CeO2 catalyst throughout the temperature range. However, the activity of the 10HT / CeO2(500) catalyst calcined at 500 °C was the best. Therefore, we believe that 500 °C is the optimal calcination temperature in the preparation process by mechanical grinding method within a certain temperature range.

[0062] Based on the above experimental results, we next selected the mechanical grinding method (the sample calcination temperature was 500 °C) to prepare HTiNbO5 / CeO2 catalysts with different loadings, and continued to explore the optimal loading ratio of HTiNbO5 modified CeO2 catalyst.

[0063] Comparative Example 6

[0064] Preparation of 5 wt% HTiNbO5 / CeO2 catalyst:

[0065] Except that the mass percentage of HTiNbO5 in the catalyst was 5 wt%, that is, 0.1 g of HTiNbO5 and 1.9 g of cerium dioxide were accurately weighed, and the preparation process was the same as that in Example 1.

[0066] Comparative Example 7

[0067] Preparation of 15 wt% HTiNbO5 / CeO2 catalyst:

[0068] Except that the mass percentage of HTiNbO5 in the catalyst was 15 wt%, that is, 0.3 g of HTiNbO5 and 1.7 g of cerium dioxide were accurately weighed, and the preparation process was the same as that in Example 1.

[0069] The catalytic activity test data of the four catalysts of Example 1 and Comparative Examples 1, 6, and 7 are shown in Table 1.

[0070] Table 1 Denitrification efficiency of HTiNbO5 / CeO2 catalysts and blank group catalysts at different temperatures

[0071] Temperature <![CDATA[CeO2]]> <![CDATA[5% HT / CeO2]]> <![CDATA[10% HT / CeO2]]> <![CDATA[15% HT / CeO2]]> 200℃ 19.48％ 38.02％ 43.99％ 40.79％ 250℃ 26.53％ 55.61％ 81.30％ 80.64％ 300℃ 40.80％ 75.02％ 85.56％ 83.46％ 350℃ 58.59％ 84.43％ 92.57％ 93.73％ 400℃ 64.11％ 92.65％ 96.24％ 96.47％

[0072] By comparing the experimental results of four catalysts, it can be found that the NO x conversion rate of all catalysts shows an upward trend as the temperature increases from 200 °C to 400 °C. This is because the increase in temperature enhances the redox properties of the catalyst. The NO x conversion rate of the pure CeO2 catalyst is only 64% after the temperature is raised to 400 °C. This is mainly because the surface acidity of pure CeO2 is relatively weak, which is not conducive to the adsorption of NH3, resulting in a relatively low denitrification efficiency. When HTiNbO5 is added, the NO x conversion rates of catalysts with different loadings all show varying degrees of increase. Comparing the experimental results of 5% HT / CeO2 and 10% HT / CeO2, that is, when the loading of HTiNbO5 increases from 5 wt% to 10 wt%, the NO x conversion rate increases from 55.61% to 81.3% at 250 °C. This is mainly attributed to the fact that HTiNbO5, as a solid acid promoter, significantly increases the number of acidic sites on the surface of the cerium-based catalyst (which is verified by the NH3-TPD results), promotes the adsorption of NH3, and thus significantly improves the catalytic efficiency. When the loading of HTiNbO5 increases from 10 wt% to 15 wt%, that is, by comparing the conversion rate data of 5% HT / CeO2 and 10% HT / CeO2 at different temperatures, it can be found that the NO x conversion rate remains basically unchanged between 200 - 400 °C. Therefore, the denitrification efficiency of the HTiNbO5-modified cerium-based catalyst is related to the loading of HTiNbO5, and a loading of 10 wt% is the optimal addition amount for the NO x conversion rate of this catalyst at various temperatures.

[0073] The acid content of the catalysts obtained in Example 1 and Comparative Examples 1, 6, and 7 was tested. The test scheme was as follows:

[0074] Catalyst acid content test

[0075] The temperature-programmed desorption experiment of ammonia (NH3-TPD) was carried out in a U-shaped quartz tube fixed-bed reactor connected to a thermal conductivity detector (TCD). First, 50 mg of the sample was accurately weighed and purged with high-purity nitrogen at 100 °C for 1 h. Then, the sample was adsorbed with NH3 at 100 °C for 30 min, and then purged with N2 at the same temperature for 30 min. Finally, the sample was heated from 100 °C to 500 °C at a heating rate of 10 °C / min under pure helium.

[0076] The test results are as Figure 3 、 4 shown. As can be seen from Figure 3It can be seen that for the HTiNbO5 / CeO2 catalyst, after introducing different loadings of HTiNbO5, its initial cubic fluorite structure of CeO2 remains unchanged. As the addition amount of HTiNbO5 increases, the diffraction peak intensity of the (111) crystal plane gradually weakens. This is because the introduction of HTiNbO5 leads to a decrease in the crystallinity of CeO2, the destruction of the structural order, an increase in the surface lattice defects of CeO2, and an increase in oxygen vacancies. And Figure 4 It shows that the NOx conversion rate of all catalysts shows an upward trend as the temperature rises from 200 °C to 400 °C; the NO x conversion rate of the pure CeO2 catalyst is only 64% after heating to 400 °C. When HTiNbO5 is added, the NO x conversion rate of the HTiNbO5 / CeO2 catalyst is significantly improved.

[0077] The catalysts obtained in Example 1 and Comparative Examples 1, 6, and 7 were subjected to a catalyst acid reducibility test. The test scheme is as follows:

[0078] Catalyst oxidation-reduction test

[0079] The hydrogen temperature-programmed reduction (H2-TPR) test experiment was carried out in a fixed U-shaped quartz tube reactor using a N2010 dual-channel chromatographic workstation connected to a thermal conductivity detector (TCD). The specific operation steps are as follows: First, the catalyst was pressed into 60-40 mesh particles, and 100 mg of the sample particles were weighed and loaded into a U-shaped quartz tube with a diameter of 5 mm; purged with high-purity nitrogen at 200 °C for 1 h, and then an Ar-H2 mixed gas (H2 volume fraction 8.5%, flow rate 30 ml / min) was connected and heated from 100 °C to 800 °C at a heating rate of 10 °C / min. The reduction curve was obtained by outputting the signal from the TCD to the chromatographic workstation and feeding it back to the computer.

[0080] The test results are as shown in Figure 5 , 6 shown. As shown in Figure 5 , with the increase of the HTiNbO5 loading, the peak position of the spectrum of the HTiNbO5 / CeO2 catalyst does not shift significantly, indicating that the introduction of HTiNbO5 has little effect on the oxidation-reduction properties of the HTiNbO5 / CeO2 catalyst, which ensures that the promotion effect after modifying CeO2 with HTiNbO5 is not affected by the oxidation-reduction property factor. And Figure 6 it shows that among these HTiNbO5 / CeO2 catalysts with different loadings, the total acid amount increases with the increase of the HTiNbO5 loading.

[0081] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A preparation method of a high-performance cerium-based denitration catalyst modified by a layered compound HTiNbO5, characterized in that: including, grinding cerium nitrate hexahydrate into a precursor powder without granularity and then calcining and activating it, and cooling it in the furnace after the calcination is completed to obtain pure CeO2 catalyst powder; mixing HTiNbO5 and CeO2, grinding them until there are no granules and the mixture is uniform, then calcining and activating them, and cooling them in the furnace after the calcination is completed to obtain HTiNbO5 / CeO2 catalyst powder.

2. The preparation method according to claim 1, characterized in that: The grinding of cerium nitrate hexahydrate mentioned above has a grinding time of 20 min.

3. The preparation method according to claim 1, characterized in that: The calcination conditions are all in a flowing air atmosphere.

4. The preparation method according to claim 3, characterized in that: The heating rate of the calcination conditions is 2 °C / min, rising from room temperature to 500 °C.

5. The preparation method according to claim 1, characterized in that: The calcination time is 5 h for all.

6. The preparation method according to claim 1, characterized in that: The cooling method is natural cooling for all.

7. The preparation method according to claim 1, characterized in that: In the HTiNbO5 / CeO2 catalyst mentioned above, the mass ratio of HTiNbO5 to CeO2 is 1:19 to 3:

17.

8. The catalyst product prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the catalyst product according to claim 8 in a denitration catalyst.

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