CN107497417B - A kind of mesoporous denitrating catalyst and the preparation method and application thereof - Google Patents

Abstract

The present invention provides a kind of mesoporous denitrating catalysts and the preparation method and application thereof, are 100% calculating with the total weight of the mesoporous denitrating catalyst, it includes the vanadium titanium zirconium composite mesopore metal oxides and binder surplus of 85-95wt%；Wherein, the vanadium titanium zirconium composite mesopore metal oxide has regular hexagonal mesoporous structure, in the vanadium titanium zirconium composite mesopore metal oxide, titanium oxide, Zirconium oxide are spaced apart composition mesoporous wall, and barium oxide is evenly distributed on the inner surface of mesopore orbit；It is in terms of 100% by the total weight of the vanadium titanium zirconium composite mesopore metal oxide, it includes the barium oxides of the titanium oxide of 30-80%, the Zirconium oxide of 25-75% and 1-10%.The catalyst that the present invention is prepared has the characteristics that large specific surface area, active component high degree of dispersion, reactant and product diffusional resistance are small, reactivity is high, the interaction of resistance to high-speed, active component and carrier is strong and thermal stability is good.

Description

A kind of mesoporous denitration catalyst and its preparation method and application

technical field

The invention relates to a mesoporous denitration catalyst, a preparation method and application thereof, and belongs to the technical field of flue gas denitration.

Background technique

Nitrogen oxides are the main causes of acid rain, photochemical smog, and air pollution, and they also have a certain damaging effect on the ozone layer. With the development of the economy and the increasingly severe environmental protection situation, the environmental protection departments have continuously increased the emission reduction requirements and efforts of various industries. Therefore, the nitrogen oxide formulation accompanying the process of flue gas and exhaust emission has also attracted people's attention. The main form of power generation in my country is thermal power, and the total number of motor vehicles is relatively large. Therefore, the emission of nitrogen oxides in my country mainly comes from the flue gas of thermal power plants and the exhaust emissions of motor vehicles. Selective catalytic reduction (SCR) technology is one of the most widely used flue gas denitrification technologies due to its high denitrification rate, mature technology, and environmentally friendly products.

The performance of the catalyst is the key to the flue gas denitration technology. Generally, the active component of the catalyst is a variable valence metal, and the carrier has a high specific surface area and good high temperature resistance. The flue gas denitration catalysts used at this stage are mainly composite _oxide catalysts such as _{TiO 2} , V ₂ O ₅ , WO ₃ and CeO ₂ . The phase of TiO ₂ undergoes a crystal transformation to generate rutile. In addition, the specific surface area of the composite oxide catalyst carrier is small, which is not conducive to the dispersion of active components, and the V ₂ O ₅ active components supported by the impregnation method are easy to sinter and fall off under high temperature conditions, which affects the denitration performance of the regenerated catalyst. have a certain impact.

Therefore, it is particularly necessary to develop a mesoporous denitration catalyst with high temperature resistance, good stability, high specific surface area and low cost.

SUMMARY OF THE INVENTION

In order to solve the above shortcomings and deficiencies, the purpose of the present invention is to provide a vanadium-titanium-zirconium composite mesoporous metal oxide.

Another object of the present invention is to provide a method for preparing the above-mentioned vanadium-titanium-zirconium composite mesoporous metal oxide.

Another object of the present invention is to provide a mesoporous denitration catalyst containing the above-mentioned vanadium-titanium-zirconium composite mesoporous metal oxide.

The present invention also aims to provide a method for preparing the above-mentioned mesoporous denitration catalyst.

The present invention also aims to provide the application of the above-mentioned mesoporous denitration catalyst in flue gas denitration.

In order to achieve the above purpose, the present invention provides a vanadium-titanium-zirconium composite mesoporous metal oxide, which has a regular hexagonal mesoporous structure. In the vanadium-titanium-zirconium composite mesoporous metal oxide, titanium oxide and zirconium oxide are separated The distribution constitutes the mesoporous pore wall, and the vanadium oxide is evenly distributed on the inner surface of the mesoporous channel;

Based on the total weight of the vanadium-titanium-zirconium composite mesoporous metal oxide as 100%, it comprises 30-80wt% titanium oxide, 25-75wt% zirconium oxide and 1-10wt% vanadium oxide; and The sum of the weight fractions of titanium oxide, zirconium oxide and vanadium oxide is 100%.

According to a specific embodiment of the present invention, preferably, the vanadium-titanium-zirconium composite mesoporous metal oxide has a specific surface area greater than 100 m ² /g, a mesopore volume of 0.5-1.2 mL/g, and an average pore diameter of 2-6 nm.

The present invention also provides a method for preparing the above-mentioned vanadium-titanium-zirconium composite mesoporous metal oxide, which comprises the following steps:

(1) Mix the titanium source and the zirconium source, and stir to form a uniform solution;

(2) pre-hydrolysis is carried out after the vanadium source is rapidly mixed with the uniform solution obtained in step (1);

(3) under stirring conditions, the solution obtained after the pre-hydrolysis is added dropwise to the deionized aqueous solution of the template agent and the alkali source, and the stirring is continued until a uniform sol is formed;

(4) crystallizing the sol solution under hydrothermal conditions, and then filtering, washing, drying and calcining to obtain a vanadium-titanium-zirconium composite mesoporous metal oxide.

According to a specific embodiment of the present invention, in the preparation method, preferably, the titanium source includes tetra-n-butyl titanate, tetraisopropyl titanate, tetraethyl titanate, tetra-tert-butyl titanate or one of the titanium sols.

According to a specific embodiment of the present invention, in the preparation method, preferably, the zirconium source comprises one of tetra-n-butyl zirconate, n-propyl zirconate or zirconium sol.

According to a specific embodiment of the present invention, in the preparation method, preferably, the vanadium source comprises an aqueous solution prepared with ammonium metavanadate and/or sodium vanadate and oxalic acid in a molar ratio of 1:2.

According to a specific embodiment of the present invention, in the preparation method, preferably, the pre-hydrolysis temperature in step (2) is 50-90°C.

According to a specific embodiment of the present invention, in the preparation method, preferably, the alkali source includes one or a combination of sodium hydroxide, potassium hydroxide and ammonia water.

According to a specific embodiment of the present invention, in the preparation method, preferably, the template agent comprises dodecyl trimethyl ammonium bromide, tetradecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium bromide One or more combinations of methylammonium bromide and octadecyltrimethylammonium bromide.

According to a specific embodiment of the present invention, in the preparation method, preferably, the molar ratio of the titanium source, zirconium source, vanadium source, template agent, alkali source and deionized water is (2.0-10.0):(1.0 -10.0):1.0:(0.5-1.5):(5.0-20.0):(100.0-500.0).

According to a specific embodiment of the present invention, in the preparation method, preferably, the temperature of the hydrothermal condition in step (4) is 120-180° C., and the reaction time is 12-72 h.

According to a specific embodiment of the present invention, in the preparation method, preferably, the drying temperature in step (4) is 80-120° C. and the time is 8-24 h.

According to a specific embodiment of the present invention, in the preparation method, preferably, the roasting temperature in step (4) is 500-650° C., and the time is 4-12 h. In a specific embodiment of the present invention, the calcination is to increase the temperature of the system from the temperature after drying to 500-650 ℃ for 4-12 hours at a heating rate of less than 5 ℃/min.

The present invention also provides a mesoporous denitration catalyst, which contains the above-mentioned vanadium-titanium-zirconium composite mesoporous metal oxide, and based on the total weight of the mesoporous denitration catalyst as 100%, it contains 85-95 wt% of the vanadium-titanium-zirconium composite Mesoporous metal oxide and binder balance.

According to a specific embodiment of the present invention, preferably, the specific surface area of the mesoporous denitration catalyst is greater than 150 m ² /g, the mesopore volume is 0.69-1.2 mL/g, and the average pore diameter is 2-10 nm;

More preferably, the mesopore volume is 0.8-1.2 mL/g.

According to a specific embodiment of the present invention, in the mesoporous denitration catalyst, preferably, the binder comprises one or more of pseudoboehmite (SB powder), aluminum hydroxide and aluminum sol combination.

The present invention also provides a method for preparing the above-mentioned mesoporous denitration catalyst, which comprises the following steps:

The mesoporous denitration catalyst is obtained by mixing the vanadium-titanium-zirconium composite mesoporous metal oxide with deionized water and a binder, then extruding or pressing into a sheet, and then drying and calcining.

According to a specific embodiment of the present invention, in the preparation method of the catalyst, preferably, the mass ratio of the vanadium-titanium-zirconium composite mesoporous metal oxide, the binder and the deionized water is 10:(1.0-3.0): (1.5-4.0).

According to a specific embodiment of the present invention, in the preparation method of the catalyst, preferably, the drying temperature is 80-120° C. and the time is 8-24 h.

According to a specific embodiment of the present invention, in the preparation method of the catalyst, preferably, the calcination temperature is 500-650° C. and the time is 4-12 h. In a specific embodiment of the present invention, the calcination is to increase the temperature of the system from the temperature after drying to 500-650 ℃ for 4-12 hours at a heating rate of less than 5 ℃/min.

The invention also provides the application of the mesoporous denitration catalyst in flue gas denitration.

The preparation method of the mesoporous denitration catalyst provided by the present invention uniformly mixes the vanadium source with the titanium source and the zirconium source by using the method of pre-hydrolysis of the titanium source, the zirconium source mixed solution and the vanadium source solution, and in the process of forming the sol solution, the mixture is uniformly mixed. The solution after pre-hydrolysis can rapidly react with the template agent to form micelles under the action of the alkali source, and then the metal oxide powder with regular hexagonal mesoporous structure is obtained after hydrothermal aging, drying and roasting; In the metal oxide powder with regular hexagonal mesoporous structure, the active components of vanadium oxide migrate slowly and evenly distribute on the inner surface of the mesoporous channels, and the titanium and zirconium oxides are distributed at intervals to form the mesoporous pore walls. Since titanium and zirconium are uniformly mixed, and zirconium oxide has good high temperature resistance, it can effectively prevent titanium oxide from undergoing crystal transformation under high temperature conditions.

The mesoporous denitration catalyst prepared by the invention has the advantages of large specific surface area, high dispersion of active components, low diffusion resistance of reactants and products, high reaction activity, high space velocity resistance, strong interaction between active components and carriers, and good thermal stability. Features, suitable for industrial applications.

Description of drawings

Fig. 1 is the TEM image of the mesoporous denitration catalyst prepared in Example 1 of the present invention;

Fig. 2 is the XRD pattern of the mesoporous destocking catalyst prepared in Example 5 of the present invention;

3 is a TEM image of the mesoporous de-stocked catalyst prepared in Example 5 of the present invention.

Detailed ways

In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solutions of the present invention are now described in detail below, but should not be construed as limiting the scope of implementation of the present invention.

Example 1

The present embodiment provides a mesoporous denitration catalyst, which is prepared by the following steps:

Mix 68.1 g of tetra-n-butyl titanate and 76.7 g of tetra-n-butyl zirconate and stir them evenly to obtain a titanium-zirconium mixed solution;

Dissolve 7.3 g of ammonium metavanadate and 11.3 g of oxalic acid in 100 mL of deionized water, heat to 80°C under stirring, and hold for 10 min to obtain a vanadium source solution;

The titanium-zirconium mixed solution is rapidly mixed with the vanadium source solution, and pre-hydrolyzed in a 60°C constant temperature water bath to form a homogeneous solution to obtain a precursor solution;

Dissolve 90g of concentrated ammonia water (25wt%) and 18.2g of cetyltrimethylammonium bromide in 450mL of deionized water, and stir until a clear solution is formed;

adding the pre-hydrolyzed precursor solution dropwise to the obtained clear solution under stirring conditions, and continuing to stir until a uniform sol solution is formed after the dropwise addition is completed;

The above-mentioned sol solution was transferred into a hydrothermal crystallization kettle, crystallized at 120°C for 72 hours, dried at 80°C for 12 hours after filtration and washing, and then heated to 550°C according to a heating rate of 2°C/min for calcination. Mesoporous metal oxide powder was obtained after 1 hour;

Mix 20g of mesoporous metal oxide powder with 6.0g of pseudo-boehmite and 8g of deionized water, and then put it into an extruder to extrude after mechanical stirring. ℃/min heating rate was raised to 550 ℃ for calcination. After calcination for 4 hours, the mesoporous denitration catalyst was obtained, which was denoted as A1. It can be seen from Fig. 1 that the catalyst has obvious regular and parallel straight pores with a pore diameter of about 2.6 nm, indicating that the catalyst prepared in this example has an obvious mesoporous structure.

Example 2

The present embodiment provides a mesoporous denitration catalyst, which is prepared by the following steps:

Mix 53.2 g of tetraisopropyl titanate and 40.9 g of n-propyl zirconate and stir to obtain a titanium-zirconium mixed solution;

Dissolve 7.3 g of ammonium metavanadate and 11.3 g of oxalic acid in 100 mL of deionized water, heat to 80°C under stirring, and hold for 10 min to obtain a vanadium source solution;

The titanium-zirconium mixed solution is rapidly mixed with the vanadium source solution, and pre-hydrolyzed in a 60°C constant temperature water bath to form a homogeneous solution to obtain a precursor solution;

Dissolve 87g of concentrated ammonia water (25wt%) and 21.0g of cetyltrimethylammonium bromide in 450mL of deionized water, and stir until a clear solution is formed;

Add the pre-hydrolyzed precursor liquid dropwise to the clear solution obtained in the previous step under stirring conditions, and continue to stir until a uniform sol liquid is formed after the dropwise addition is completed;

The above-mentioned sol solution was transferred into a hydrothermal crystallization kettle, crystallized at 140°C for 48 hours, filtered and washed, dried at 100°C for 10 hours, then heated to 500°C according to a heating rate of 2°C/min, and roasted for 4 hours. Mesoporous metal oxide powder was obtained after 1 hour;

Mix 20g of mesoporous metal oxide powder with 4.5g of aluminum hydroxide and 7.0g of deionized water, and then put it into an extruder to extrude after mechanical stirring. The heating rate was increased to 500°C per minute for calcination, and the mesoporous denitration catalyst was obtained after calcination for 16 hours, which was denoted as A2.

Example 3

The present embodiment provides a mesoporous denitration catalyst, which is prepared by the following steps:

Mix 128.0 g of tetraethyl titanate and 143.6 g of tetra-n-butyl zirconate and stir them evenly to obtain a titanium-zirconium mixed solution;

Dissolve 7.3 g of ammonium metavanadate and 11.3 g of oxalic acid in 100 mL of deionized water, heat to 90° C. under stirring, and hold for 10 min to obtain a vanadium source solution;

The titanium-zirconium mixed solution is rapidly mixed with the vanadium source solution, and pre-hydrolyzed in a constant temperature water bath at 70°C to form a uniform solution to obtain a precursor solution;

Dissolve 52.4g of concentrated ammonia water (25wt%) and 12.1g of cetyltrimethylammonium bromide in 450mL of deionized water, and stir until a clear solution is formed;

Add the pre-hydrolyzed precursor liquid dropwise to the clear solution obtained in the previous step under stirring conditions, and continue to stir until a uniform sol liquid is formed after the dropwise addition is completed;

The above-mentioned sol solution was transferred into a hydrothermal crystallization kettle, crystallized at 160°C for 40 hours, filtered and washed, dried at 120°C for 8 hours, then heated to 600°C according to a heating rate of 2°C/min and roasted for 6 hours. Mesoporous metal oxide powder was obtained after 1 hour;

20g of mesoporous metal oxide powder was mixed with 5.0g of pseudo-boehmite and 6.0g of deionized water, and then put into an extruder for extruding after mechanical stirring, and dried at 100°C for 14 hours after molding. The temperature was raised to 500°C at a heating rate of 2°C/min for calcination. After calcination for 8 hours, a mesoporous denitration catalyst was obtained, which was denoted as A3.

Example 4

The present embodiment provides a mesoporous denitration catalyst, which is prepared by the following steps:

Mix 130.0 g of titanium sol (containing 25.1 wt % of TiO ₂ ) and 76.7 g of zirconium sol (containing 27.2 wt % of ZrO ₂ ), and stir them evenly to obtain a titanium-zirconium mixed solution;

Dissolve 7.3 g of ammonium metavanadate and 11.3 g of oxalic acid in 100 mL of deionized water, heat to 80°C under stirring, and hold for 10 min to obtain a vanadium source solution;

The titanium-zirconium mixed solution is rapidly mixed with the vanadium source solution, and pre-hydrolyzed in a constant temperature water bath at 65°C to form a uniform solution to obtain a precursor solution;

Dissolve 39.5g of concentrated ammonia water (25wt%) and 24.5g of cetyltrimethylammonium bromide in 450mL of deionized water, and stir until a clear solution is formed;

Add the pre-hydrolyzed precursor liquid dropwise to the clear solution obtained in the previous step under stirring conditions, and continue to stir until a uniform sol liquid is formed after the dropwise addition is completed;

The above-mentioned sol solution was transferred into a hydrothermal crystallization kettle, crystallized at 180°C for 12 hours, filtered and washed, and dried at 100°C for 6 hours. Mesoporous metal oxide powder was obtained after 1 hour;

Mix 20 g of mesoporous metal oxide powder with 3.0 g of pseudo-boehmite and 5.0 g of deionized water, and then put it into an extruder for extruding after mechanical stirring. The temperature was raised to 550°C at a heating rate of 2°C/min for calcination, and the mesoporous denitration catalyst was obtained after calcination for 10 hours, which was denoted as A4.

Example 5

The present embodiment provides a mesoporous denitration catalyst, which is prepared by the following steps:

89.6 g of tetra-tert-butyl titanate and 81.7 g of tetra-n-butyl zirconate were mixed and stirred evenly to obtain a titanium-zirconium mixed solution;

Dissolve 7.3 g of ammonium metavanadate and 11.3 g of oxalic acid in 100 mL of deionized water, heat to 80°C under stirring, and hold for 10 min to obtain a vanadium source solution;

The titanium-zirconium mixed solution is rapidly mixed with the vanadium source solution, and pre-hydrolyzed in a 60°C constant temperature water bath to form a homogeneous solution to obtain a precursor solution;

Dissolve 90g of concentrated ammonia water (25wt%) and 18.2g of cetyltrimethylammonium bromide in 450mL of deionized water, and stir until a clear solution is formed;

Add the pre-hydrolyzed precursor liquid dropwise to the clear solution obtained in the previous step under stirring conditions, and continue to stir until a uniform sol liquid is formed after the dropwise addition is completed;

The above-mentioned sol solution was transferred into a hydrothermal crystallization kettle, crystallized at 120°C for 72 hours, dried at 80°C for 12 hours after filtration and washing, and then heated to 550°C according to a heating rate of 2°C/min for calcination. Mesoporous metal oxide powder was obtained after 1 hour;

Mix 20 g of mesoporous metal oxide powder with 2.0 g of pseudo-boehmite and 6.0 g of deionized water, and then put it into an extruder for extruding after mechanical stirring. The heating rate of 2°C/min was heated to 550°C for calcination. After calcination for 4 hours, the mesoporous denitration catalyst was obtained, which was denoted as A5. Hexagonal mesoporous arrangement in the direction of the vertical orifice);

It can be seen from Figure 2 that the XRD pattern has an obvious diffraction peak at 2° and two weak diffraction peaks at 4-6°, which correspond to the 100, 110 and 200 crystal planes of the material with hexagonal mesoporous structure, respectively. , this conclusion further proves that the catalyst prepared by the present invention has a regular hexagonal mesoporous structure;

It can be clearly observed from Figure 3 that the catalyst has pores arranged regularly in a "honeycomb" shape.

Application example

This application example evaluates the performance of the mesoporous denitration catalyst prepared in Examples 1-5. The reaction conditions are: normal pressure, 300 ° C, the loading amount of the mesoporous denitration catalyst is 2.0 g; the raw material gas is NO, NH _3. A mixture of N ₂ and O ₂ , wherein the volume fraction of NO and NH ₃ is 0.08%, the volume fraction of O ₂ is 2.5%, and the total gas volume space velocity GHSV=12000h ^-1 . The corresponding performance parameters and activity measurement results of each catalyst are shown in Table 1:

Table 1

It can be seen from Table 1 that the mesoporous denitration catalyst prepared in the present application is used for flue gas denitration reaction, and it has a high NOx conversion rate, which shows that the catalyst has high reaction activity and high space velocity resistance.

Claims (24)

1. A vanadium-titanium-zirconium composite mesoporous metal oxide, which has a regular hexagonal mesoporous structure, and in the vanadium-titanium-zirconium composite mesoporous metal oxide, titanium oxide and zirconium oxide are distributed at intervals to form mesoporous pore walls , the vanadium oxides are uniformly distributed on the inner surface of the mesoporous channels; Based on the total weight of the vanadium-titanium-zirconium composite mesoporous metal oxide as 100%, it comprises 30-80wt% titanium oxide, 25-75wt% zirconium oxide and 1-10wt% vanadium oxide; and The sum of the weight fractions of titanium oxide, zirconium oxide and vanadium oxide is 100%. 2 . The vanadium-titanium-zirconium composite mesoporous metal oxide according to claim 1 , wherein the specific surface area of the vanadium-titanium-zirconium composite mesoporous metal oxide is greater than 100 m ² /g, and the mesopore volume is 0.5-1.2 mL/g, the average pore size is 2-6nm. 3. the preparation method of the vanadium titanium zirconium composite mesoporous metal oxide described in claim 1 or 2, it comprises the following steps: (1) Mix the titanium source and the zirconium source, and stir to form a uniform solution; (2) pre-hydrolysis is carried out after the vanadium source is rapidly mixed with the uniform solution obtained in step (1); (3) under stirring conditions, the solution obtained after the pre-hydrolysis is added dropwise to the deionized aqueous solution of the template agent and the alkali source, and the stirring is continued until a uniform sol is formed; (4) crystallizing the sol solution under hydrothermal conditions, and then filtering, washing, drying and calcining to obtain a vanadium-titanium-zirconium composite mesoporous metal oxide. 4. The preparation method according to claim 3, wherein the titanium source comprises tetra-n-butyl titanate, tetraisopropyl titanate, tetraethyl titanate, tetra-tert-butyl titanate or titanium One of the sols. 5 . The preparation method according to claim 3 , wherein the zirconium source comprises one of tetra-n-butyl zirconate, n-propyl zirconate or zirconium sol. 6 . 6 . The preparation method according to claim 4 , wherein the zirconium source comprises one of tetra-n-butyl zirconate, n-propyl zirconate or zirconium sol. 7 . 7. preparation method according to claim 3, is characterized in that, described vanadium source comprises the solution that ammonium metavanadate and/or sodium vanadate and oxalic acid molar ratio are 1:2. 8 . The preparation method according to claim 3 , wherein the prehydrolysis temperature is 50-90° C. 9 . 9 . The preparation method according to claim 3 , wherein the alkali source comprises one or more combinations of sodium hydroxide, potassium hydroxide and ammonia water. 10 . 10. preparation method according to claim 3 is characterized in that, described templating agent comprises dodecyl trimethyl ammonium bromide, tetradecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium bromide One or more combinations of ammonium bromide and octadecyltrimethylammonium bromide. 11. preparation method according to claim 9, is characterized in that, described templating agent comprises dodecyl trimethyl ammonium bromide, tetradecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium bromide One or more combinations of ammonium bromide and octadecyltrimethylammonium bromide. 12 . The preparation method according to claim 3 , wherein the temperature of the hydrothermal condition is 120-180° C., and the reaction time is 12-72 h. 13 . 13 . The preparation method according to claim 3 , wherein the drying temperature in step (4) is 80-120° C. and the time is 8-24 h. 14 . 14 . The preparation method according to claim 3 , wherein the roasting temperature in step (4) is 500-650° C. and the time is 4-12 h. 15 . 15. The preparation method according to any one of claims 3-14, wherein the molar ratio of the titanium source, zirconium source, vanadium source, template, alkali source and deionized water is (2.0-10.0) :(1.0-10.0):1.0:(0.5-1.5):(5.0-20.0):(100.0-500.0). 16. A mesoporous denitration catalyst comprising the vanadium-titanium-zirconium composite mesoporous metal oxide according to claim 1 or 2, calculated on the basis of the total weight of the mesoporous denitration catalyst as 100%, which comprises 85-95wt% of Vanadium-titanium-zirconium composite mesoporous metal oxide and the balance of the binder. 17 . The mesoporous denitration catalyst according to claim 16 , wherein the specific surface area of the mesoporous denitration catalyst is greater than 150 m ² /g, the mesopore volume is 0.69-1.2 mL/g, and the average pore diameter is 2-10 nm. 18 . . 18. The mesoporous denitration catalyst according to claim 17, wherein the mesopore volume is 0.8-1.2 mL/g. 19 . The mesoporous denitration catalyst according to claim 16 , wherein the binder comprises one or a combination of pseudoboehmite, aluminum hydroxide and aluminum sol. 20 . 20. the preparation method of the mesoporous denitration catalyst described in any one of claim 16-19, it comprises the following steps: The mesoporous denitration catalyst is obtained by mixing the vanadium-titanium-zirconium composite mesoporous metal oxide with deionized water and a binder, then extruding or pressing into a sheet, and then drying and calcining. 21. preparation method according to claim 20 is characterized in that, the mass ratio of described vanadium titanium zirconium composite mesoporous metal oxide, binder and deionized water is 10:(1.0-3.0):(1.5- 4.0). 22 . The preparation method according to claim 20 , wherein the drying temperature is 80-120° C. and the time is 8-24 h. 23 . 23. The preparation method according to any one of claims 20-22, wherein the roasting temperature is 500-650°C, and the time is 4-12h. 24. Application of the mesoporous denitration catalyst according to any one of claims 16-19 in flue gas denitration.