Low-temperature sulfur-resistant and water-resistant denitration catalyst as well as preparation method and application thereof

Abstract

The invention discloses a low-temperature sulfur-resistant and water-resistant denitration catalyst as well as a preparation method and application thereof, and belongs to the technical field of environmental catalysis. The low-temperature sulfur-resistant and water-resistant denitration catalyst comprises a titanium dioxide carrier, an active component V2O5 and an auxiliary agent P-MoO3, the mass of the titanium dioxide carrier is taken as a reference, the active component V2O5 accounts for 1%-10% of the mass of the titanium dioxide carrier, the mass of the auxiliary agent P-MoO3 accounts for 1%-10% of the mass of the titanium dioxide carrier, and the atomic ratio of Mo atoms to doped P atoms in the auxiliary agent P-MoO3 is (1-10): 1. The method is used for solving the technical problem that the low-temperature denitration performance of the catalyst is inhibited due to the fact that the oxidation-reduction capacity of the catalyst is often weakened when acidic sites are introduced in the prior art.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of environmental catalysis, and particularly relates to a low-temperature sulfur-resistant and water-resistant denitration catalyst as well as a preparation method and application thereof. BACKGROUND

[0002] As the core part of the most widely used SCR method for treating NOx, the denitration catalyst will soon reach a replacement peak. The main problem of the low-temperature denitration catalyst is low activity at low temperature and short service life. In recent years, the proportion of NOx emissions from industrial boilers (kilns) in non-power industries has been rising, and has become an important source of air pollution. Due to the low flue gas temperature in the steel, cement, glass and other non-power industries, the traditional catalysts have high working temperature, resulting in increased operating costs. Therefore, the catalyst must be improved to improve its applicability in the field of low-temperature flue gas denitration. Based on the above industry problems, it is imperative to develop a high-performance low-temperature denitration catalyst. The high-performance low-temperature denitration catalyst not only has excellent performance, but also can meet the ultra-low emission of flue gas under complex conditions in non-power industries.

[0003] The surface acidity of the catalyst is closely related to the SO2 and H2O resistance. The stronger the acidity, the more the number of Lewis acid sites and Bronsted acid sites is increased. The increased surface acidity can provide more adsorption sites for NH3, thereby improving the SO2 and H2O resistance of the catalyst. The acid modification of the oxidation-reduction catalyst is often realized by different preparation methods (such as impregnation method, coprecipitation, etc.) or surface doping.

[0004] For example, in the Chinese invention patent with the publication number CN104084213A, a surfactant CTAB is added, and active components manganese oxides and various component additives are introduced to improve the sulfur and water resistance. In the Chinese invention patent with the publication number CN113318746A, a FeCeO x powder is prepared by a coprecipitation method, and then the FeCeO x powder, citric acid and oxalic acid are dissolved in distilled water and uniformly stirred at room temperature. Finally, a high-performance medium-low temperature NH3 SCR catalyst is prepared by drying and calcining in an air atmosphere. In the Chinese invention patent with the publication number CN115193442A, Mo doping is used to improve the surface acidity of Fe2O3, thereby improving the denitration efficiency and reducing the adsorption of SO2. However, the above methods often weaken the oxidation-reduction ability of the catalyst while introducing acid sites, thereby inhibiting the low-temperature denitration performance of the catalyst. SUMMARY

[0005] In order to overcome the above-mentioned defects of the prior art, the present application aims to provide a low-temperature sulfur-resistant and water-resistant denitration catalyst, a preparation method and application thereof, so as to solve the technical problem that the introduction of acid sites often weakens the redox ability of the catalyst, thereby inhibiting the low-temperature denitration performance of the catalyst.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions: The present application provides a low-temperature sulfur-resistant and water-resistant denitration catalyst, which comprises a titanium dioxide carrier, an active component V2O5 and an auxiliary agent P-MoO3, wherein, based on the mass of the titanium dioxide carrier, the active component V2O5 accounts for 1%-10% of the mass of the titanium dioxide carrier, and the auxiliary agent P-MoO3 accounts for 1%-10% of the mass of the titanium dioxide carrier; and the atomic ratio of Mo atoms to doped P atoms in the auxiliary agent P-MoO3 is (1-10):1.

[0007] The present application also provides a preparation method of a low-temperature sulfur-resistant and water-resistant denitration catalyst, which comprises the following steps: S1, dissolving a molybdate and a phosphate in water to prepare a solution A, and then adding oxalic acid to perform a first reaction to prepare a solution B; S2, dissolving a vanadate and oxalic acid in water to perform a second reaction to prepare a solution C; S3, mixing the solution C and the solution B to prepare an impregnation solution; S4, impregnating a titanium dioxide carrier in the impregnation solution, and then sequentially performing drying and calcination to prepare a catalyst.

[0008] In an embodiment, in S1, the concentration ratio of Mo atoms to P atoms in the solution A is (1-10):1; and the amount of water used is 5mL-10mL.

[0009] In an embodiment, in S1, the molar ratio of Mo atoms to oxalic acid in the solution A is 1:(1-5).

[0010] In an embodiment, in S1, the molybdate is one or more of ammonium molybdate, sodium molybdate and magnesium molybdate; and the phosphate is one or more of ammonium phosphate trihydrate, ammonium monohydrogen phosphate, ammonium dihydrogen phosphate, sodium phosphate dodecahydrate, sodium monohydrogen phosphate and sodium dihydrogen phosphate.

[0011] In an embodiment, in S2, the vanadate is one or more of vanadyl oxalate, vanadyl sulfate, sodium metavanadate, sodium metavanadate, ammonium metavanadate and ammonium metavanadate.

[0012] In an embodiment, in S2, the molar ratio of the vanadate to oxalic acid is 1:(1-5); and the amount of water used is 5mL-10mL.

[0013] In an embodiment, in S4, the titanium dioxide carrier is one of anatase or rutile or a mixture of both.

[0014] In an embodiment, in S1, the temperature of the first reaction is 80-100 DEG C, and the time is 10-60 min; in S2, the temperature of the second reaction is 80-100 DEG C, and the time is 10-60 min; in S4, the temperature of the drying is 80-120 DEG C, and the time is 6-12 h; the temperature of the calcination is 400-600 DEG C, and the time is 4-8 h.

[0015] The application also provides application of the low-temperature sulfur-resistant and water-resistant denitration catalyst in a denitration process.

[0016] Compared with the prior art, the application has the following beneficial effects: The application provides a low-temperature sulfur-resistant and water-resistant denitration catalyst, which uses a mixture of a specific kind and content of phosphate and molybdenum (V) and molybdenum (VI) as an acid center to increase surface acidity, provide more adsorption sites, and thus improve the activity and SO2 and H2O resistance of the catalyst. The catalyst structure of the dual-center synergistic effect of the "active center" of V2O5 and the "acid center" of P-MoO3 promotes the mass transfer and diffusion of the reactant molecules NH3 and NO, and improves the redox performance of the catalyst.

[0017] The catalyst is prepared by the impregnation method, and the method is simple and easy to operate, and is suitable for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A preparation method of the low-temperature sulfur-resistant and water-resistant denitration catalyst is shown in the figure. DETAILED DESCRIPTION

[0019] To enable those skilled in the art to understand the characteristics and effects of the application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used in the text are the usual meanings understood by those skilled in the art for the application, and in case of conflict, the definition in the specification shall prevail.

[0020] Theories or mechanisms described and disclosed herein, whether correct or not, should not be used to limit the scope of the application, that is, the content of the application can be implemented without being limited by any particular theory or mechanism.

[0021] Herein, all features defined by numerical ranges or percentage ranges, such as numerical values, amounts, contents and concentrations, are merely for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered to have encompassed and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0022] Herein, unless otherwise specifically indicated, the terms "comprise", "comprising", "contain", "containing", "have", "having", or any other similar phrase are intended to encompass "consist of" and "consist essentially of" for example, "A comprises a" encompasses "A comprises a and other" and "A comprises only a".

[0023] Herein, for the sake of brevity, all possible combinations of the various technical features in the various embodiments or examples are not described. Therefore, the various technical features in the various embodiments or examples can be combined with each other in any manner as long as there is no contradiction, and all possible combinations should be considered as falling within the scope of the present specification.

[0024] One aspect of the present application provides a low-temperature sulfur-resistant and water-resistant denitration catalyst, in which the active component V2O5 accounts for 1-10% of the mass of the titanium dioxide carrier, and the additive P-MoO3 accounts for 1-10% of the mass of the titanium dioxide carrier (wherein the atomic ratio of Mo and doped P is (1-10):1). The above-mentioned low-temperature sulfur-resistant and water-resistant denitration catalyst uses titanium dioxide as the carrier, vanadium oxide as the active component, and P-MoO3 as the additive to form a denitration catalyst with a specific type and content of phosphate and a mixture of molybdenum (V) and molybdenum (VI) as the acid center. This catalyst structure with dual-center synergistic effect of "active center" and "acid center" promotes the mass transfer and diffusion of reactant molecules NH3 and NO, and at the same time improves the denitration efficiency of the catalyst and the resistance to SO2 and H2O at low temperature.

[0025] As shown in Figure 1 Another aspect of the present application provides a preparation method of a low-temperature sulfur-resistant and water-resistant denitration catalyst, which comprises the following steps: (1) Dissolve molybdate and phosphate with a molybdenum atom to phosphorus atom concentration ratio of 1:1-10:1 in 5-10 mL of water, add oxalic acid in a molar amount of 1-5 times that of molybdenum atoms, and react at 80-100°C for 10-60 min; preferably, add oxalic acid in a molar amount of twice that of molybdenum atoms; preferably, the reaction time is 30 min; (2) a certain amount of vanadium salt and oxalic acid in a molar amount of 1-5 times of vanadium atom are added into 5-10 mL water to dissolve, and the solution is reacted at 80-100 °C for 10-60 min; preferably, oxalic acid in a molar amount of 2 times of vanadium atom is added; preferably, the reaction time is 30 min; (3) the solution in step (2) is added into the solution in step (1) to obtain an impregnation solution; (4) the impregnation solution is impregnated on TiO2, and dried at 80-120 °C for 6-12 h and calcined at 400-600 °C for 4-8 h to obtain the low-temperature sulfur and water resistant denitration catalyst. Preferably, the drying time is 12 h, and the calcination time is 4 h.

[0026] In the low-temperature sulfur and water resistant denitration catalyst, the active component V2O5 accounts for 1-10 wt% of the mass of the TiO2 carrier, and the additive P-MoO3 accounts for 1-10 wt% of the mass of the carrier (wherein the atomic ratio of Mo and doped P is (1-10):1).

[0027] In some embodiments, the molybdate salt in step (1) is one or more of ammonium molybdate, sodium molybdate, and magnesium molybdate.

[0028] In some embodiments, the phosphate salt in step (1) is one or more of ammonium phosphate trihydrate, ammonium monohydrogen phosphate, ammonium dihydrogen phosphate, sodium phosphate dodecahydrate, sodium monohydrogen phosphate, and sodium dihydrogen phosphate.

[0029] In some embodiments, the vanadium salt in step (2) is one or more of vanadyl oxalate, vanadyl sulfate, sodium metavanadate, sodium metavanadate, ammonium metavanadate, and ammonium metavanadate.

[0030] In some embodiments, the TiO2 in step (3) is one or a mixture of both of anatase and rutile.

[0031] The application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the application and not used to limit the scope of the application. Furthermore, it should be understood that those skilled in the art can make various modifications or changes to the application after reading the content of the application, and these equivalent forms also fall within the scope of the appended claims.

[0032] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0033] Example 1 (1) Dissolve 1.43g sodium molybdate and 0.26g sodium phosphate dodecahydrate in 5mL of water (the ratio of molybdenum atoms to phosphorus atoms is 10:1), add 1.75g ​​oxalic acid dihydrate, and react at 80℃ for 30min; (2) Dissolve 2.69g of vanadium oxalate and 2.69g of oxalic acid dihydrate in 5mL of water and react at 80℃ for 30min; (3) Add the solution from step (2) to the solution after the reaction in step (1) to obtain the impregnation solution; (4) The above impregnation solution is impregnated on 10g TiO2, dried at 80℃ for 12 hours, and calcined at 400℃ for 4 hours to obtain the low-temperature anti-sulfur and anti-water denitrification catalyst. Among them, based on the mass of titanium dioxide support, the active component V2O5 accounts for 10wt% of the support mass, and the auxiliary agent P-MoO3 accounts for 10wt% of the support mass (wherein the ratio of Mo to doped P atoms is 10:1).

[0034] Example 2 (1) Dissolve 1.43g sodium molybdate and 0.08g sodium dihydrogen phosphate in 10mL of water (the ratio of molybdenum atoms to phosphorus atoms is 10:1), add 1.75g ​​oxalic acid dihydrate, and react at 80℃ for 30min; (2) Dissolve 2.69g of vanadium oxalate and 2.69g of oxalic acid dihydrate in 5mL of water and react at 80℃ for 30min; (3) Add the solution from step (2) to the solution after the reaction in step (1) to obtain the impregnation solution; (4) The above impregnation solution is impregnated on 10g TiO2, dried at 80℃ for 12 hours, and calcined at 600℃ for 4 hours to obtain the low-temperature anti-sulfur and anti-water denitrification catalyst. Among them, based on the mass of titanium dioxide support, the active component V2O5 accounts for 10wt% of the support mass, and the auxiliary agent P-MoO3 accounts for 10wt% of the support mass (wherein the ratio of Mo to doped P atoms is 10:1).

[0035] Example 3 (1) Dissolve 1.28g magnesium molybdate and 0.08g sodium dihydrogen phosphate in 5mL of water (the ratio of molybdenum atoms to phosphorus atoms is 10:1), add 1.75g ​​oxalic acid dihydrate, and react at 80℃ for 30min; (2) Dissolve 1.43g of vanadium sulfate and 2.15g of oxalic acid dihydrate in 8mL of water and react at 100℃ for 30min; (3) Add the solution from step (2) to the solution after the reaction in step (1) to obtain the impregnation solution; (4) The above impregnation solution is impregnated on 10g TiO2, dried at 80℃ for 12 hours, and calcined at 600℃ for 4 hours to obtain the low-temperature anti-sulfur and anti-water denitrification catalyst. Among them, based on the mass of titanium dioxide support, the active component V2O5 accounts for 8wt% of the support mass, and the auxiliary agent P-MoO3 accounts for 10wt% of the support mass (wherein the ratio of Mo to doped P atoms is 10:1).

[0036] Example 4 (1) Dissolve 0.98g ammonium molybdate and 0.13g ammonium dihydrogen phosphate in 8mL of water (the ratio of molybdenum atoms to phosphorus atoms is 5:1), add 1.40g oxalic acid dihydrate, and react at 80℃ for 30min; (2) Dissolve 1.79g of vanadium oxysulfate and 2.69g of oxalic acid dihydrate in 8mL of water and react at 100℃ for 30min; (3) Add the solution from step (2) to the solution after the reaction in step (1) to obtain the impregnation solution; (4) The above impregnation solution is impregnated on 10g TiO2, dried at 80℃ for 12 hours, and calcined at 600℃ for 4 hours to obtain the low-temperature anti-sulfur and anti-water denitrification catalyst. Among them, based on the mass of titanium dioxide support, the active component V2O5 accounts for 10wt% of the support mass, and the auxiliary agent P-MoO3 accounts for 8wt% of the support mass (where the ratio of Mo to doped P atoms is 5:1).

[0037] Example 5 (1) Dissolve 0.98g ammonium molybdate and 0.22g ammonium dihydrogen phosphate in 10mL of water (the ratio of molybdenum atoms to phosphorus atoms is 3:1), add 1.40g oxalic acid dihydrate, and react at 80℃ for 30min; (2) Dissolve 1.79g of vanadium oxysulfate and 2.69g of oxalic acid dihydrate in 8mL of water and react at 100℃ for 30min; (3) Add the solution from step (2) to the solution after the reaction in step (1) to obtain the impregnation solution; (4) The above impregnation solution is impregnated on 10g TiO2, dried at 80℃ for 12 hours, and calcined at 600℃ for 4 hours to obtain the low-temperature anti-sulfur and anti-water denitrification catalyst. Among them, based on the mass of titanium dioxide support, the active component V2O5 accounts for 10wt% of the support mass, and the auxiliary agent P-MoO3 accounts for 8wt% of the support mass (where the ratio of Mo to doped P atoms is 3:1).

[0038] Example 6 (1) Dissolve 0.98g of ammonium molybdate and 0.37g of ammonium phosphate trihydrate in 8mL of water (the ratio of molybdenum atoms to phosphorus atoms is 3:1), add 1.40g of oxalic acid dihydrate, and react at 80℃ for 30min; (2) Dissolve 1.79g of vanadium oxysulfate and 2.69g of oxalic acid dihydrate in 10mL of water and react at 80℃ for 30min; (3) Add the solution from step (2) to the solution after the reaction in step (1) to obtain the impregnation solution; (4) The above impregnation solution is impregnated on 10g TiO2, dried at 80℃ for 12 hours, and calcined at 600℃ for 4 hours to obtain the low-temperature anti-sulfur and anti-water denitrification catalyst. Among them, based on the mass of titanium dioxide support, the active component V2O5 accounts for 10wt% of the support mass, and the auxiliary agent P-MoO3 accounts for 8wt% of the support mass (where the ratio of Mo to doped P atoms is 3:1).

[0039] Example 7 (1) Dissolve 0.98g of ammonium molybdate and 0.37g of ammonium phosphate trihydrate in 10mL of water (the ratio of molybdenum atoms to phosphorus atoms is 3:1), add 1.40g of oxalic acid dihydrate, and react at 80℃ for 30min; (2) Dissolve 1.64g of sodium metavanadate and 2.15g of oxalic acid dihydrate in 10mL of water and react at 80℃ for 30min; (3) Add the solution from step (2) to the solution after the reaction in step (1) to obtain the impregnation solution; (4) The above impregnation solution is impregnated on 10g TiO2, dried at 80℃ for 12 hours, and calcined at 600℃ for 4 hours to obtain the low-temperature anti-sulfur and anti-water denitrification catalyst. Among them, based on the mass of titanium dioxide support, the active component V2O5 accounts for 8wt% of the support mass, and the auxiliary agent P-MoO3 accounts for 8wt% of the support mass (where the ratio of Mo to doped P atoms is 3:1).

[0040] Example 8 (1) Dissolve 0.61g of ammonium molybdate and 0.35g of ammonium phosphate trihydrate in 5mL of water (the ratio of molybdenum atoms to phosphorus atoms is 2:1), add 0.88g of oxalic acid dihydrate, and react at 80℃ for 30min; (2) Dissolve 1.57g of ammonium metavanadate and 2.15g of oxalic acid dihydrate in 8mL of water and react at 80℃ for 30min; (3) Add the solution from step (2) to the solution after the reaction in step (1) to obtain the impregnation solution; (4) The above impregnation solution is impregnated on 10g TiO2, dried at 80℃ for 12 hours, and calcined at 500℃ for 4 hours to obtain the low-temperature anti-sulfur and anti-water denitrification catalyst. Among them, based on the mass of titanium dioxide support, the active component V2O5 accounts for 8wt% of the support mass, and the auxiliary agent P-MoO3 accounts for 5wt% of the support mass (where the ratio of Mo to doped P atoms is 2:1).

[0041] Example 9 (1) Dissolve 0.61g of ammonium molybdate and 0.35g of ammonium phosphate trihydrate in 5mL of water (the ratio of molybdenum atoms to phosphorus atoms is 2:1), add 0.88g of oxalic acid dihydrate, and react at 80℃ for 30min; (2) Dissolve 0.98g of ammonium metavanadate and 1.34g of oxalic acid dihydrate in 5mL of water and react at 80℃ for 30min; (3) Add the solution from step (2) to the solution after the reaction in step (1) to obtain the impregnation solution; (4) The above impregnation solution is impregnated on 10g TiO2, dried at 80℃ for 12 hours, and calcined at 500℃ for 4 hours to obtain the low-temperature anti-sulfur and anti-water denitrification catalyst. Among them, based on the mass of titanium dioxide support, the active component V2O5 accounts for 5wt% of the support mass, and the auxiliary agent P-MoO3 accounts for 5wt% of the support mass (wherein the ratio of Mo to doped P atoms is 2:1).

[0042] Example 10 (1) Dissolve 0.61g of ammonium molybdate and 0.70g of ammonium phosphate trihydrate in 5mL of water (the ratio of molybdenum atoms to phosphorus atoms is 1:1), add 0.88g of oxalic acid dihydrate, and react at 80℃ for 30min; (2) Dissolve 0.98g of ammonium metavanadate and 1.34g of oxalic acid dihydrate in 5mL of water and react at 80℃ for 30min; (3) Add the solution from step (2) to the solution after the reaction in step (1) to obtain the impregnation solution; (4) The above impregnation solution is impregnated on 10g TiO2, dried at 80℃ for 12 hours, and calcined at 500℃ for 4 hours to obtain the low-temperature anti-sulfur and anti-water denitrification catalyst. Among them, based on the mass of titanium dioxide support, the active component V2O5 accounts for 5wt% of the support mass, and the auxiliary agent P-MoO3 accounts for 5wt% of the support mass (wherein the ratio of Mo to doped P atoms is 1:1).

[0043] Comparative Example (1) Take 0.61g of ammonium molybdate and add 0.88g of oxalic acid dihydrate, and react at 80℃ for 30min; (2) Take 0.98g of ammonium metavanadate and dissolve it with 1.34g of oxalic acid dihydrate, and react at 80℃ for 30min; (3) Add the solution from step (2) to the solution after the reaction in step (1) and continue the reaction for 30 minutes; (4) The above solution was impregnated on 10g TiO2, dried at 80℃ for 12 hours, and calcined at 500℃ for 4 hours to obtain the catalyst. Among them, based on the mass of the titanium dioxide support, the active component V2O5 accounts for 5wt% of the support mass, and the auxiliary agent MoO3 accounts for 5wt% of the support mass.

[0044] The difference between the comparative example and Example 10 is that no phosphate was added, resulting in a catalyst.

[0045] Catalyst denitrification performance test: The catalyst prepared above was loaded into a stainless steel fixed-bed reactor with an inner diameter of 10 mm, and the feed gas was introduced into the reactor to carry out the denitrification reaction. The test conditions were: NO 1000 mg / Nm³. 3 O2 10%, SO2 50 mg / Nm 3 10% H2O, NH3 / NO molar ratio of 1.0, N2 as balance gas, space velocity 23000 h⁻¹ 1 The catalyst volume is 5 ml. NO at the inlet and outlet was measured at temperatures of 140℃, 150℃, 160℃, and 180℃, respectively. x The concentration of [amount] was detected using a Testo portable flue gas analyzer. The denitrification activity test results for different catalysts are shown in Table 1 below: Table 1. Denitrification activity test results of different catalysts

[0046] As shown in Table 1, the catalyst activity is higher than that of the catalyst without added phosphate by adding phosphate, and the catalyst activity also increases with the increase of phosphate.

[0047] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A low-temperature sulfur- and water-resistant denitrification catalyst, characterized in that, It includes a titanium dioxide carrier, an active component V2O5, and an additive P-MoO3. Based on the mass of the titanium dioxide carrier, the active component V2O5 accounts for 1%-10% of the mass of the titanium dioxide carrier, and the additive P-MoO3 accounts for 1%-10% of the mass of the titanium dioxide carrier. The atomic ratio of Mo atoms to doped P atoms in the additive P-MoO3 is (1-10):

1.

2. A method for preparing a low-temperature sulfur- and water-resistant denitrification catalyst as described in claim 1, characterized in that, Includes the following steps: S1, dissolve molybdate and phosphate in water to prepare solution A, then add oxalic acid to carry out the first reaction to prepare solution B; S2, vanadium salt and oxalic acid are dissolved in water to carry out the second reaction, and solution C is obtained; S3, mix solution C and solution B to prepare an impregnation solution; S4. The titanium dioxide support is impregnated in the impregnation solution, and then dried and calcined in sequence to obtain the catalyst.

3. The preparation method of the low-temperature sulfur-resistant and water-resistant denitrification catalyst according to claim 2, characterized in that, In S1, the concentration ratio of molybdenum atoms to phosphorus atoms in solution A is (1-10):1; the amount of water used is 5mL-10mL.

4. The preparation method of the low-temperature sulfur-resistant and water-resistant denitrification catalyst according to claim 2, characterized in that, In S1, the molar ratio of molybdenum atoms to oxalic acid in solution A is 1:(1-5).

5. The preparation method of the low-temperature sulfur-resistant and water-resistant denitrification catalyst according to claim 2, characterized in that, In S1, the molybdate is one or more of ammonium molybdate, sodium molybdate, and magnesium molybdate; the phosphate is one or more of ammonium phosphate trihydrate, ammonium monohydrogen phosphate, ammonium dihydrogen phosphate, sodium phosphate dodecahydrate, sodium monohydrogen phosphate, and sodium dihydrogen phosphate.

6. The preparation method of the low-temperature sulfur-resistant and water-resistant denitrification catalyst according to claim 2, characterized in that, In S2, the vanadium salt is one or more of the following: vanadium oxalate, vanadium sulfate, sodium vanadate, sodium metavanadate, ammonium vanadate, and ammonium metavanadate.

7. The preparation method of the low-temperature sulfur-resistant and water-resistant denitrification catalyst according to claim 2, characterized in that, In S2, the molar ratio of the vanadium salt to oxalic acid is 1:(1-5); the amount of water used is 5mL-10mL.

8. The preparation method of the low-temperature sulfur-resistant and water-resistant denitrification catalyst according to claim 2, characterized in that, In S4, the titanium dioxide carrier is one or a mixture of two types: anatase and rutile.

9. The preparation method of the low-temperature sulfur-resistant and water-resistant denitrification catalyst according to claim 2, characterized in that, In S1, the temperature of the first reaction is 80℃-100℃ and the time is 10min-60min; in S2, the temperature of the second reaction is 80℃-100℃ and the time is 10min-60min; in S4, the drying temperature is 80℃-120℃ and the time is 6h-12h; the calcination temperature is 400℃-600℃ and the time is 4h-8h.

10. The application of the low-temperature sulfur- and water-resistant denitrification catalyst as described in claim 1 in the denitrification reaction process.

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