Denitration catalyst with low sulfur dioxide oxidation rate and preparation and application thereof

Abstract

The invention discloses a denitration catalyst with a low sulfur dioxide oxidation rate, a preparation method of the denitration catalyst and application of the denitration catalyst in removal of nitrogen oxides through ammonia selective catalytic reduction. The denitration catalyst with the low sulfur dioxide oxidation rate is a titanium dioxide loaded vanadium pentoxide, molybdenum oxide and cerium oxide catalyst subjected to phosphorylation treatment. The preparation method comprises the following steps: (1) preparing a first solid-liquid mixture in which a vanadium pentoxide precursor, a molybdenum oxide precursor, a cerium oxide precursor and titanium dioxide are uniformly dispersed, drying the first solid-liquid mixture, grinding and roasting to obtain an intermediate product; and (2) preparing a second solid-liquid mixture in which the intermediate product and the precursor for phosphorylation are uniformly dispersed, drying the second solid-liquid mixture, grinding, and roasting to obtain the denitration catalyst with low sulfur dioxide oxidation rate. The low-cost control of NOx is realized, and the generation of sulfur trioxide is reduced at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of air pollution control, and in particular to a denitration catalyst with a low sulfur dioxide oxidation rate, a preparation method and an application thereof. Background Art

[0002] Nitrogen oxides (NO x ) and sulfur dioxide (SO2) are widely present in many industrial flue gases as air pollutants, such as coal-fired power plants, coke ovens in the steel industry, biomass boilers, etc. x Ozone (O3) and PM 2.5 SO2 is an important precursor of NO formation, and SO3 is easily oxidized by catalysts to sulfur trioxide (SO3). SO3 is easy to corrode the pipeline system of subsequent equipment. In order to prevent corrosion, the heating temperature of subsequent flue gas has to be increased, which increases energy consumption and reduces the efficiency of air preheater. At the same time, SO3 is easy to react with ammonia in flue gas to form ammonium bisulfate, which leads to the blockage of gas pipeline. In addition, SO3 is harmful to human health. Therefore, when removing NO x Under the premise of reducing the oxidation of SO2 to SO3, it is of great significance to environmental protection and human health.

[0003] At present, the method of reducing the oxidation rate of SO2 by the catalyst for removing nitrogen oxides is mostly to reduce the SO2 at the inlet, that is, to set up a desulfurization device before the denitrification device to remove SO2 in the flue gas, but the temperature of the flue gas after desulfurization is usually low, and it still needs to be heated to the reaction temperature before entering the denitrification device, which increases the energy consumption of the flue gas treatment system. Secondly, there is also a method of using subsequent SO3 treatment, but after the process of removing nitrogen oxides, a large part of SO3 exists in the form of sulfate species, which increases the difficulty of treatment.

[0004] Regarding the simultaneous occurrence of NH3-SCR reaction and SO2 oxidation reaction in the removal of nitrogen oxides, if you want to selectively react with SCR reaction without SO2 oxidation reaction, you need to make the catalyst more reactive to NO x It selectively adsorbs NH3 and reduces the reaction energy barrier, while reducing the adsorption of SO2 and increasing the oxidation energy barrier. Generally, catalysts for removing nitrogen oxides have high redox properties, and high redox properties will cause SCR reaction and SO2 oxidation at high temperature, making the nitrogen oxide removal efficiency and SO2 oxidation rate show a common reaction trend. Therefore, this is also the main problem in the current catalyst design. In addition, the actual industrial flue gas components are complex, and the water resistance of the catalyst is also a key factor to be considered in catalyst design. Therefore, the development of a catalyst for removing nitrogen oxides with a wide temperature window, high activity, high stability and a low SO2 oxidation rate has broad application prospects and development significance.

[0005] The Chinese patent document with publication number CN108187657A discloses a thin-walled SCR denitrification catalyst with low sulfur dioxide oxidation rate and its preparation method, wherein vanadium pentoxide is loaded on the surface of titanium dioxide catalyst to remove NO x At the same time, it also achieves the inhibition of SO2 oxidation, but the catalyst has problems such as complex preparation process, difficult to control sulfur dioxide oxidation rate under thin wall and unstable denitrification performance.

[0006] A Chinese patent document with publication number CN106994301A discloses a high-efficiency SCR denitrification structure that can reduce the sulfur dioxide / sulfur trioxide conversion rate. The oxidation rate of sulfur dioxide by the SCR catalyst is reduced by multi-stage combustion and air recycling. However, the structure is relatively complex and has high energy consumption. It does not directly reduce the oxidation rate of sulfur dioxide on the catalyst.

[0007] A Chinese patent document with publication number CN103240077A discloses a denitrification catalyst with a low sulfur dioxide oxidation rate and a preparation method thereof. The catalyst is prepared by mixing titanium dioxide, vanadium pentoxide, tungsten trioxide, niobium oxide, rare earth oxides, and silicon-aluminum composite oxides. The oxidation rate of sulfur dioxide is reduced while maintaining the SCR catalytic activity unchanged. However, the activity is still not high, and there is still a lot of room for the sulfur dioxide oxidation rate to decrease.

[0008] Although the above literature has provided some help in the development of catalysts for removing nitrogen oxides with low sulfur dioxide oxidation rates, it still has disadvantages such as narrow temperature window, high preparation cost, poor denitrification performance, and poor water resistance, which hinder the industrial application of NH3-SCR catalysts in high sulfur dioxide flue gas treatment.

[0009] Therefore, the development of a new NH3-SCR catalyst that can be used in the SCR denitrification process of high sulfur dioxide flue gas with high activity over a wide temperature window, low sulfur dioxide oxidizability, water resistance and relatively low preparation cost has broad application prospects and development significance. Summary of the invention

[0010] In view of the above technical problems and the shortcomings in the art, the present invention provides a denitration catalyst with low sulfur dioxide oxidation rate and its preparation method and application. The denitration catalyst of the present invention has excellent characteristics such as wide temperature window, high activity, high stability, etc., and can achieve low-cost control of NO x At the same time, it reduces the production of sulfur trioxide, overcoming the SO2 oxidation problem and water resistance problem of the current denitrification catalyst.

[0011] [1] A denitration catalyst with a low sulfur dioxide oxidation rate, wherein the denitration catalyst with a low sulfur dioxide oxidation rate is a phosphorylated titanium dioxide-supported vanadium pentoxide, molybdenum oxide and cerium oxide catalyst, which can be recorded as P-VMoCe / Ti.

[0012] The present invention adopts a multi-metal loading structure combined with phosphorylation treatment to solve the above technical problems, while ensuring high denitration performance and reducing SO2 oxidation. Among them, vanadium pentoxide (V2O5) is a good medium- and high-temperature denitration catalyst, which can achieve NO x The catalyst can effectively remove NOx; molybdenum oxide (MO3) further improves the denitration efficiency, stability and water resistance of the catalyst. In addition, cerium oxide (CeO2) can improve the dispersion of V2O5 on the carrier and form a vanadium-cerium interaction to protect V2O5 from being adsorbed by SO2; phosphorylation further improves the catalyst's adsorption of NH3 and reduces the adsorption of SO2. The above combined effects effectively reduce the catalyst's oxidation of SO2 in a denitration environment and effectively improve the removal efficiency of nitrogen oxides. At the same time, the catalyst has good water resistance, so it can maintain a good nitrogen oxide removal efficiency in actual industrial flue gas.

[0013] In the denitration catalyst with low sulfur dioxide oxidation rate, based on the mass of titanium dioxide as 100%, the mass proportion of vanadium element can be 0.5% to 1%, such as 0.7%, the mass proportion of molybdenum element can be 4% to 8%, such as 6%, the mass proportion of cerium element can be 2% to 6%, preferably 3% to 5%, more preferably 4%, the mass proportion of phosphorus element can be 3% to 7%, preferably 4% to 6%, more preferably 5%. The catalyst under the preferred conditions can show 100% nitrogen oxide removal efficiency and greater than 98% N2 selectivity and less than 0.8% sulfur dioxide oxidation rate in the temperature window of 250 to 350°C.

[0014] [2] A method for preparing a denitration catalyst having a low sulfur dioxide oxidation rate according to [1], comprising the steps of:

[0015] (1) preparing a first solid-liquid mixture in which a vanadium pentoxide precursor, a molybdenum oxide precursor, a cerium oxide precursor and titanium dioxide are evenly dispersed, drying the first solid-liquid mixture, grinding it, and roasting it to obtain an intermediate product;

[0016] (2) preparing a second solid-liquid mixture in which the intermediate product and a precursor for phosphorylation are evenly dispersed, drying the second solid-liquid mixture, grinding it, and roasting it to obtain the denitration catalyst with a low sulfur dioxide oxidation rate.

[0017] In the preparation method of the present invention, a catalyst in which transition metals are supported on titanium dioxide is first prepared by a wet impregnation method, and then a phosphoric acid functional group is introduced by phosphorylation treatment, and the obtained multi-metal supported phosphorylated catalyst is used for the treatment of nitrogen oxides in sulfur-containing waste gas. The main active site for removing nitrogen oxides in this catalyst is the vanadium active site, the molybdenum site serves the purpose of widening the temperature window and enhancing water resistance, and the cerium strengthens the acidity and stability of the vanadium site, and combined with phosphorylation, it enhances the inhibitory effect on SO2 adsorption and inhibits the oxidation of SO2 to generate the intermediate VOSO4. NH3 is adsorbed on the vanadium site, and NO reacts with NH3 on the vanadium site to generate water and nitrogen; while SO2 is difficult to adsorb on the vanadium site, and the formed VOSO4 intermediate is difficult to decompose to generate SO3. The advantage of this multi-metal supported phosphorylated catalyst is that it not only improves the catalyst's removal efficiency for nitrogen oxides, but also limits the oxidation of SO2, and has a high N2 selectivity.

[0018] In step (1), the vanadium pentoxide precursor may be ammonium metavanadate.

[0019] In step (1), the molybdenum oxide precursor may be ammonium heptamolybdate.

[0020] In step (1), the cerium oxide precursor may be at least one of cerium nitrate and ammonium cerium nitrate.

[0021] In step (1), the titanium dioxide may be P25.

[0022] In step (1), the calcination temperature may be 450-550° C., such as 500° C., and the calcination time may be 4-6 hours, such as 5 hours.

[0023] In step (2), the precursor for phosphorylation may be at least one of ammonium dihydrogen phosphate and diammonium hydrogen phosphate.

[0024] In step (2), the calcination temperature may be 350-550°C, preferably 400-500°C, more preferably 400°C, and the calcination time may be 2-5h, preferably 3-5h, more preferably 3h. The catalyst under the preferred conditions may exhibit 100% nitrogen oxide removal efficiency and greater than 98% N2 selectivity and less than 0.8% sulfur dioxide oxidation rate within the temperature window of 250-350°C.

[0025] [3] Use of the denitration catalyst with a low sulfur dioxide oxidation rate according to [1] in the removal of nitrogen oxides by selective catalytic reduction of ammonia.

[0026] [3] During the application process, the denitrification catalyst with a low sulfur dioxide oxidation rate can inhibit sulfur dioxide oxidation and reduce sulfur trioxide generation.

[0027] [3] During the application, the temperature for removing nitrogen oxides by selective catalytic reduction of ammonia may be 200 to 450°C, and further may be 250 to 400°C.

[0028] [3] In the application process, the environment for removing nitrogen oxides by selective catalytic reduction of ammonia may contain water vapor. Furthermore, the volume fraction of water vapor may be 0.1% to 20%.

[0029] [4] A method for removing nitrogen oxides by selective catalytic reduction of ammonia, using the denitrification catalyst with a low sulfur dioxide oxidation rate described in [1].

[0030] [4] In the method, the denitrification catalyst with a low sulfur dioxide oxidation rate can inhibit sulfur dioxide oxidation and reduce sulfur trioxide generation.

[0031] [4] In the method, the temperature for removing nitrogen oxides by selective catalytic reduction of ammonia may be 200 to 450°C, and further may be 250 to 400°C.

[0032] [4] In the method, the environment for removing nitrogen oxides by selective catalytic reduction of ammonia may contain water vapor. Furthermore, the volume fraction of water vapor may be 0.1% to 20%.

[0033] The denitration catalyst with a low sulfur dioxide oxidation rate of the present invention is particularly suitable for treating nitrogen oxides in flue gas at the front end of a flue gas treatment project.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1) The sulfur resistance of denitrification catalysts does not mean low sulfur dioxide oxidation, and sulfur-resistant denitrification catalysts may have high sulfur dioxide oxidation performance. The multi-metal-supported phosphorylated catalyst prepared by the present invention can achieve efficient removal of nitrogen oxides within a wide temperature window, effectively inhibit the oxidation of sulfur dioxide, and reduce the formation of sulfur trioxide in exhaust gas.

[0036] 2) The catalyst prepared by the present invention has a certain water resistance, improves the N2 selectivity of the reaction, and can meet the complex working conditions under actual conditions.

[0037] 3) The present invention uses transition metals and P25 as precursors to achieve efficient removal of nitrogen oxides under conditions of a lower SO2 oxidation rate on the catalyst, thereby reducing the cost of removing pollutants. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0039] Example 1

[0040] Catalyst preparation:

[0041] (1) A certain amount of vanadium pentoxide, molybdenum oxide, and cerium oxide precursors were added to a certain amount of P25 titanium dioxide, and the mass ratios of vanadium pentoxide, molybdenum oxide, cerium oxide, and carrier titanium dioxide were controlled to be 0.7%, 6%, and 2%, respectively. Then, 100 mL of deionized water was added, and the mixture was stirred for 5 h and ultrasonicated for 1 h to be evenly dispersed. 8 g of carrier P25 titanium dioxide was added, 0.072 g of vanadium pentoxide precursor NH4VO3 was added, and 0.06 g of molybdenum oxide precursor H 24 Mo7N6O 24 · 0.588g of 4H2O and 0.509g of cerium oxide precursor (NH4)2Ce(NO3)6;

[0042] (2) After being evenly dispersed, the solid-liquid mixture is dried at 120 degrees Celsius for 12 hours, the solid product is ground into powder and sieved through 200 mesh, and the powder is calcined at 500 degrees Celsius for 5 hours to obtain an intermediate product;

[0043] (3) Add 0.518 g of diammonium hydrogen phosphate ((NH4)2HPO4) to the intermediate product obtained in step (2) to maintain a mass ratio of P element to carrier TiO2 of 5%, add deionized water, stir for 4 h, and perform ultrasonic treatment for 0.5 h to achieve uniform dispersion;

[0044] (4) The solid-liquid mixture was dried at 120 degrees Celsius for 12 hours, the solid product was ground into powder and sieved through 200 mesh, and the powder was calcined at 400 degrees Celsius for 3 hours to obtain the catalyst of Example 1.

[0045] Example 2

[0046] The only difference from Example 1 is that the amount of cerium oxide precursor (NH4)2Ce(NO3)6 is increased to 1.019 g, and the mass ratio of cerium oxide to carrier titanium dioxide is controlled to 4%. The rest is the same, and the catalyst of Example 2 is obtained.

[0047] Example 3

[0048] The only difference from Example 1 is that the amount of cerium oxide precursor (NH4)2Ce(NO3)6 is increased to 1.528 g, the mass ratio of cerium oxide to carrier titanium dioxide is controlled to 6%, and the rest is the same, to obtain the catalyst of Example 3.

[0049] Example 4

[0050] The only difference from Example 2 is that the calcination temperature and time in (4) are changed to 500 degrees Celsius and 5 hours, and the rest are the same, to obtain the catalyst of Example 4.

[0051] Example 5

[0052] The only difference from Example 2 is that the amount of diammonium hydrogen phosphate ((NH4)2HPO4) is changed to 0.310 g to maintain the mass ratio of P element to carrier TiO2 at 3%. The rest is the same, and the catalyst of Example 5 is obtained.

[0053] Example 6

[0054] The only difference from Example 2 is that the amount of diammonium hydrogen phosphate ((NH4)2HPO4) is changed to 0.725 g to maintain the mass ratio of P element to carrier TiO2 at 7%. The rest is the same, and the catalyst of Example 6 is obtained.

[0055] Example 7

[0056] The only difference from Example 6 is that the amount of cerium oxide precursor (NH4)2Ce(NO3)6 is increased to 1.528 g, the mass ratio of cerium oxide to carrier titanium dioxide is controlled to 6%, and the rest are the same, to obtain the catalyst of Example 7.

[0057] Example 8

[0058] Catalyst preparation:

[0059] (1) Add a certain amount of vanadium pentoxide, molybdenum oxide, and cerium oxide precursors to a certain amount of P25 titanium dioxide, and add a phosphorylated precursor at the same time, and control the mass ratio of vanadium pentoxide, molybdenum oxide, cerium oxide, P element and carrier titanium dioxide to be 0.7%, 6%, 4%, and 5%. Then add 100 mL of deionized water, stir for 5 hours and ultrasonically treat for 1 hour to disperse evenly. Add 8 g of carrier P25 titanium dioxide, 0.072 g of vanadium pentoxide precursor NH4VO3, and 0.06 g of molybdenum oxide precursor H 24 Mo7N6O 24 · Add 0.588g of 4H2O, 1.019g of cerium oxide precursor (NH4)2Ce(NO3)6, and 0.518g of phosphate precursor diammonium hydrogen phosphate ((NH4)2HPO4);

[0060] (2) After being evenly dispersed, the solid-liquid mixture was dried at 120 degrees Celsius for 12 hours, the solid product was ground into powder and sieved through 200 mesh, and the powder was calcined at 500 degrees Celsius for 5 hours to obtain the catalyst of Example 8.

[0061] Comparative Example 1

[0062] Catalyst preparation:

[0063] (1) A certain amount of vanadium pentoxide and molybdenum oxide precursors were added to a certain amount of P25 titanium dioxide, and the mass ratio of vanadium pentoxide, molybdenum oxide and carrier titanium dioxide was controlled to be 0.7% and 6%, respectively. Then 100 mL of deionized water was added, and the mixture was stirred for 5 h and ultrasonicated for 1 h to be evenly dispersed. 8 g of carrier P25 titanium dioxide was added, 0.072 g of vanadium pentoxide precursor NH4VO3 was added, and 0.06 g of molybdenum oxide precursor H 24 Mo7N6O 24 4H2O added 0.588g;

[0064] (2) After being evenly dispersed, the solid-liquid mixture was dried at 120 degrees Celsius for 12 hours, the solid product was ground into powder and sieved through 200 mesh, and the powder was calcined at 500 degrees Celsius for 5 hours to obtain an intermediate product, namely the catalyst of Comparative Example 1.

[0065] Comparative Example 2

[0066] The only difference from Example 1 is that the cerium oxide precursor (NH4)2Ce(NO3)6 is not added, and the rest is the same, obtaining the catalyst of Comparative Example 2.

[0067] Application Example 1

[0068] The catalysts prepared in Examples 1 to 8 and Comparative Examples 1 to 2 were subjected to nitrogen oxide (NO x ) to explore the optimal component ratio and preparation conditions. The details are as follows:

[0069] The activity test was carried out in a fixed bed reactor, with a catalyst loading of 2.3 mL and a particle size of 40-60 mesh. The initial gas volume concentration was: [NO] = 500 ppm, [NH3] = 500 ppm, [SO2] = 200 ppm, [O2] = 5 vol%, [H2O] = 5 vol%, N2 as carrier gas, GHSV (gas space velocity) = 40000 h -1 The test reaction temperatures were 200°C, 250°C, 300°C, 350°C, 400°C, and 450°C. The test data of NO conversion rate after 1h of reaction are shown in Table 1. x Ideally, it should be selectively oxidized to N2 and H2O. Therefore, N2 selectivity is also an important factor in evaluating catalyst performance. In this experiment, the N2 selectivity in the activity experiment was further investigated. The data are shown in Table 2.

[0070] The results are expressed in terms of NO conversion and N2 selectivity, and the calculation method is shown in the following formula:

[0071]

[0072] The test data are detailed in Table 1 and Table 2.

[0073] Table 1 Catalytic reduction efficiency of catalysts for NO (%)

[0074]

[0075] Table 2 Catalyst denitration N2 selectivity / %

[0076]

[0077] By comparing Comparative Example 2 with Examples 1 to 3, it can be found that in the activity test experiment of the multi-metal loaded phosphorylation catalyst of the present invention for removing nitrogen oxides, the optimal proportion of cerium oxide loading is 4%, and it has a nitrogen oxide removal efficiency of 100% and a N2 selectivity of more than 98% within the temperature window of 250 to 400°C.

[0078] By comparing Examples 2, 5 and 6, it can be found that in the activity test experiment of the multi-metal supported phosphorylation catalyst of the present invention for removing nitrogen oxides, the optimal ratio of phosphorylation-supported phosphorus element is 5%.

[0079] By comparing Examples 2, 4, and 8, it can be found that the multi-metal supported phosphorylation catalyst of the present invention needs to be prepared by a two-step method in the activity test experiment of removing nitrogen oxides, and the optimal condition for the secondary calcination is calcination at 400 degrees Celsius for 3 hours.

[0080] Application Example 2

[0081] The catalysts prepared in Examples 1 to 8 and Comparative Examples 1 to 2 were subjected to a sulfur dioxide (SO2) oxidation rate test to explore whether the catalyst with a high nitrogen oxide removal rate has a lower SO2 oxidation rate. The details are as follows:

[0082] The test was carried out in a fixed bed reactor, with a catalyst loading of 2.3 mL and a particle size of 40-60 mesh. The initial gas volume concentrations were: [NO] = 300 ppm, [NH3] = 300 ppm, [SO2] = 2000 ppm, [O2] = 5 vol%, [H2O] = 5 vol%, N2 as carrier gas, GHSV (gas space velocity) = 40000 h -1 The test reaction temperatures were specifically 250°C, 300°C, 350°C, and 400°C. The test data of SO2 oxidation rate after 1 hour of reaction are shown in Table 3.

[0083] The results are expressed in terms of SO2 oxidation rate, which is calculated as follows:

[0084]

[0085] The test data is detailed in Table 3.

[0086] Table 3 Catalyst oxidation rate of SO2 / %

[0087]

[0088] By comparing Comparative Examples 1 and 2 with Example 2, it can be found that the multi-metal supported phosphorylation catalyst P-VMoCe / Ti of the present invention maintains a 100% conversion rate for removing nitrogen oxides in the range of 250 to 400 degrees Celsius, maintains an N2 selectivity of more than 98%, and a sulfur dioxide oxidation rate of less than 0.8%.

[0089] The advantages of the multi-metal supported phosphorylation catalyst of the present invention are: 1. wide temperature window, high denitration activity, and low sulfur dioxide oxidation rate; 2. good water resistance, sulfur resistance, and stability.

[0090] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A denitration catalyst with a low sulfur dioxide oxidation rate, characterized in that: The denitration catalyst with low sulfur dioxide oxidation rate is a phosphorylated titanium dioxide-supported vanadium pentoxide, molybdenum oxide and cerium oxide catalyst.

2. The denitration catalyst with low sulfur dioxide oxidation rate according to claim 1, characterized in that: In the denitration catalyst with a low sulfur dioxide oxidation rate, based on the mass of titanium dioxide as 100%, the mass of vanadium element accounts for 0.5% to 1%, the mass of molybdenum element accounts for 4% to 8%, the mass of cerium element accounts for 2% to 6%, preferably 3% to 5%, and more preferably 4%; the mass of phosphorus element accounts for 3% to 7%, preferably 4% to 6%, and more preferably 5%.

3. The method for preparing a denitration catalyst with a low sulfur dioxide oxidation rate according to claim 1 or 2, characterized in that: Includes steps: (1) preparing a first solid-liquid mixture in which a vanadium pentoxide precursor, a molybdenum oxide precursor, a cerium oxide precursor and titanium dioxide are evenly dispersed, drying the first solid-liquid mixture, grinding it, and roasting it to obtain an intermediate product; (2) preparing a second solid-liquid mixture in which the intermediate product and a precursor for phosphorylation are evenly dispersed, drying the second solid-liquid mixture, grinding it, and roasting it to obtain the denitration catalyst with a low sulfur dioxide oxidation rate.

4. The preparation method according to claim 3, characterized in that: In step (1): The vanadium pentoxide precursor is ammonium metavanadate; The molybdenum oxide precursor is ammonium heptamolybdate; The cerium oxide precursor is at least one of cerium nitrate and ammonium cerium nitrate; The titanium dioxide is P25; The calcination temperature is 450-550° C. and the calcination time is 4-6 hours.

5. The preparation method according to claim 3, characterized in that: In step (2): The precursor for phosphorylation is at least one of ammonium dihydrogen phosphate and diammonium hydrogen phosphate; The calcination temperature is 350-550° C., preferably 400-500° C., more preferably 400° C., and the calcination time is 2-5 h, preferably 3-5 h, more preferably 3 h.

6. Use of the denitration catalyst with low sulfur dioxide oxidation rate according to claim 1 or 2 in removing nitrogen oxides by selective catalytic reduction of ammonia.

7. The use according to claim 6, characterized in that: During the application process: The denitration catalyst with a low sulfur dioxide oxidation rate can inhibit sulfur dioxide oxidation and reduce sulfur trioxide generation; The temperature for removing nitrogen oxides by selective catalytic reduction of ammonia is 200 to 450°C, further 250 to 400°C; The environment for removing nitrogen oxides by selective catalytic reduction of ammonia contains water vapor, and the volume fraction of the water vapor is 0.1% to 20%.

8. A method for removing nitrogen oxides by selective catalytic reduction of ammonia, characterized in that: A denitration catalyst with a low sulfur dioxide oxidation rate as claimed in claim 1 or 2 is used.

9. The method for removing nitrogen oxides by selective catalytic reduction of ammonia according to claim 8, characterized in that: In the method: The denitration catalyst with a low sulfur dioxide oxidation rate can inhibit sulfur dioxide oxidation and reduce sulfur trioxide generation; The temperature for removing nitrogen oxides by selective catalytic reduction of ammonia is 200 to 450°C, further 250 to 400°C; The environment for removing nitrogen oxides by selective catalytic reduction of ammonia contains water vapor, and the volume fraction of the water vapor is 0.1% to 20%.

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