Low airspeed SCR catalyst and preparation method thereof

Abstract

The invention discloses a low-airspeed SCR catalyst and a preparation method thereof.The catalyst comprises a coating and a supporting layer, the coating comprises a coating material, tungsten-doped (5%) anatase type nanometer titanium dioxide, titanium dioxide and SSZ-13 molecular sieve mixture, and the content of the coating material accounts for 56.1 wt%-75.6 wt% of the total loading amount; the method comprises the following steps: preparing a supporting layer solution and a coating material; preparing catalyst slurry; drying the catalyst carrier with the supporting layer solution; applying a catalyst slurry to a catalyst support; and roasting and drying to obtain the catalyst. According to the invention, the coating uniformity and efficiency are improved by coating the supporting layer solution and the catalyst slurry, so that the NOx conversion efficiency of the catalyst in a low air speed state is improved.

Description

Technical Field

[0001] The invention relates to the technical field of industrial tail gas purification and treatment, in particular to a method for preparing a low space velocity SCR catalyst. Background Art

[0002] Selective catalytic reduction technology is an environmentally friendly technology widely used in industrial flue gas denitrification, also known as SCR catalytic technology. This technology uses a reducing agent (such as ammonia, urea or ammonia water) under the action of a catalyst to selectively reduce nitrogen oxides (NOx) in flue gas into non-toxic and non-polluting nitrogen (N 2 ) and water (H 2 O). SCR catalyst is the core of SCR technology. Its structure and performance directly affect the denitrification effect. The type, structure and surface area of ​​the catalyst have a significant impact on the NOx removal effect. The construction cost of SCR catalyst accounts for more than 20% of the cost of flue gas denitrification project, and the operating cost accounts for more than 30%. The most commonly used catalyst is V 2 O 5 -WO 3 (MoO 3 ) / TiO 2 series, among which TiO 2 As the main carrier, V 2 O 5 As the main active ingredient, WO 3 、MoO 3 It is an auxiliary component for anti-oxidation and anti-poisoning. The catalyst types can be divided into plate type, honeycomb type and corrugated plate type.

[0003] In-depth research on catalyst production technology and molding process is an important part of the future development of SCR technology. At the same time, with the improvement of environmental protection requirements, the SCR catalyst industry will enter a stable demand stage, but since the existing domestic production capacity is still lower than the market scale, how to increase production capacity while ensuring the improvement of catalytic performance has become an urgent problem to be solved. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem of NO x In order to solve the problem of low conversion efficiency, a low space velocity SCR catalyst and a preparation method thereof are provided, which improves the coating uniformity and efficiency by coating the support layer solution and the catalyst slurry, thereby improving the NO conversion of the catalyst under low space velocity state. x Conversion efficiency.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions:

[0006] A low space velocity SCR catalyst comprises a coating layer and a support layer, wherein:

[0007] The coating comprises:

[0008] The coating material is a mixture of tungsten-doped (5%) anatase nano-titanium dioxide, titanium dioxide and SSZ-13 molecular sieve, with a content of 56.1wt% to 75.6wt% of the total loading;

[0009] Active ingredient, V 2 O 5 A mixture of transition metal oxides, wherein V 2 O 5 The content is 3.0wt% to 7.0wt% of the total loading, and the precursor is a vanadium salt; the content of the transition metal oxide is 6.8wt% to 15.3wt% of the total loading, and the precursor is a transition metal salt;

[0010] Binder, silicon dioxide, the precursor is silica sol, the content is 4.2wt% to 9.0wt% of the total load;

[0011] The support layer comprises SSZ-13 molecular sieve, and the support layer accounts for 10.0 wt% to 15.0 wt% of the total loading.

[0012] Furthermore, the support layer comprises SSZ-13 molecular sieve and alumina, the SSZ-13 molecular sieve accounts for 90.0wt% to 100.0wt%, and the alumina layer accounts for 0.0wt% to 10.0wt%;

[0013] In the coating material, the tungsten-doped (5%) anatase nano-titanium dioxide accounts for 0.0wt% to 40.0wt%, the titanium dioxide accounts for 50.0wt% to 90.0wt%, and the SSZ-13 molecular sieve accounts for 0.0wt% to 10.0wt%.

[0014] In the present invention, tungsten-doped (5%) anatase nano-titanium dioxide is used. 3 Distributed to the surface of the material, the dispersion is more uniform. After mixing the titanium dioxide material, a layer of WO 3 , make WO 3 There is a gap in the thickness distribution on the surface of the mixed material, which increases the acid sites inside and on the surface of the mixed material, promotes the formation of V-O-W on the surface of the mixed material and increases V 5+ ratio, improve the low temperature performance, and broaden the catalyst activity range; the addition of zirconium inhibits V 2 O 5 Polymerization at high temperature improves the thermal stability of the catalyst and increases the vacant oxygen sites on the surface of the coating material, thus improving the resistance to SO in practical applications. 2 and H 2 O ability;

[0015] The support layer composed of SSZ-13 molecular sieve has an increased specific surface area due to its octahedral pores and three-dimensional cross-pore crystal structure, which increases the coating and NO X The contact area improves the catalyst efficiency; and forms a unique dendritic structure between the catalyst carrier and the coating, which affects the direction of the airflow passing through the inner surface of the catalyst, slows down the flow rate, and improves the catalytic performance;

[0016] Vanadium metal ions and transition metal ions are preferentially added as active components under acidic liquid phase conditions, and the coating materials are mixed in proportion so that the active components are evenly dispersed on the surface and pores of the coating materials in a liquid phase environment, providing more attachment sites for the active components, increasing the contact area between the active substances and the reactants, and improving the catalyst performance.

[0017] A method for preparing a low space velocity SCR catalyst comprises the following steps:

[0018] preparing a supporting layer solution and a coating material;

[0019] Mixing and dissolving vanadium salt and transition metal salt to prepare catalyst slurry;

[0020] preparing a catalyst carrier, coating the catalyst carrier with a supporting layer solution, and drying the catalyst carrier with the supporting layer solution;

[0021] After drying the catalyst carrier with the supporting layer solution, coating the catalyst slurry on the catalyst carrier, and drying the catalyst carrier with the catalyst slurry;

[0022] The catalyst carrier with the catalyst slurry is calcined and dried to obtain a low space velocity SCR catalyst.

[0023] Further, spreading the supporting layer solution comprises the following steps:

[0024] Place the catalyst carrier horizontally with the pore surface facing upward;

[0025] The end surface of the pore surface is evenly covered with the support layer solution, and the catalyst carrier is shaken until the support layer solution flows into the pores of the catalyst carrier;

[0026] The catalyst carrier with the supporting layer solution is dried.

[0027] Further, spreading the catalyst slurry comprises the following steps:

[0028] Place the catalyst carrier horizontally with the pore surface facing upward;

[0029] The end surface of the pore surface is evenly covered with the support layer solution, and the catalyst carrier is shaken until the support layer solution flows into the pores of the catalyst carrier;

[0030] The catalyst carrier with the catalyst slurry is dried.

[0031] Furthermore, preparing the supporting layer solution comprises the following steps:

[0032] The SSZ-13 molecular sieve, alumina and glacial acetic acid are mixed in a mass ratio to obtain a support layer mixture, wherein:

[0033] SSZ-13 molecular sieve accounts for 86wt% to 92wt%, alumina accounts for 0wt% to 7wt%, and glacial acetic acid accounts for 0wt% to 7wt%;

[0034] Grinding the support layer mixture by mechanical ball milling for 0.1 h to 0.5 h;

[0035] A supporting layer solution is prepared.

[0036] Furthermore, the preparation of the coating material comprises the following steps:

[0037] Mixing tungsten-doped (5%) anatase nano-titanium dioxide, titanium dioxide and SSZ-13 molecular sieve according to a mass ratio to obtain a coating mixture, wherein the tungsten-doped (5%) anatase nano-titanium dioxide accounts for 0.0wt% to 40.0wt%, the titanium dioxide accounts for 50.0wt% to 90.0wt%, and the SSZ-13 molecular sieve accounts for 0.0wt% to 10.0wt%;

[0038] Grinding the coating mixture by mechanical ball milling for 0.1 h to 0.5 h;

[0039] Made into coating material.

[0040] Furthermore, the catalyst slurry preparation comprises the following steps:

[0041] Mix and dissolve the vanadium salt and transition metal salt, stir for 0.5h to 1h, mix evenly, and adjust the pH to 3 to 6;

[0042] Add additives, raise the temperature to 60℃~90℃, keep warm for 0.5h~1h, then add coating materials and additives, raise the temperature to 60℃~90℃, keep stirring and keep warm for 1h~3h. After the insulation is completed, cool the solution to room temperature;

[0043] Add a binder, adjust the pH to 6-8, and stir for 3-5 hours to prepare a catalyst slurry.

[0044] The catalyst loading amount is 150 g / L to 260 g / L.

[0045] Further, the additive includes one or a combination of any two or more of ethylene glycol, glucose, sodium borohydride, ascorbic acid, and citric acid, and the content thereof is V 2 O5 1 to 3 times;

[0046] The auxiliary agent includes one or a combination of any two or more of hydrochloric acid, nitric acid, acetic acid, oxalic acid, ethylenediamine, and ethanolamine, and its content is V 2 O 5 0.207 to 0.345 times.

[0047] The binder is silica sol, which accounts for 4.2wt% to 9.0wt% of the total load.

[0048] Furthermore, when the catalyst carrier with the catalyst slurry is calcined and dried, a drying temperature of 110° C. to 150° C., a drying time of 0.5 h to 2 h, a calcination temperature of 450° C. to 550° C., and a calcination time of 1 h to 3 h are adopted.

[0049] The addition of SSZ-13 molecular sieve in the coating material, with its high specific surface area and acidity, provides more surface B acid sites and L acid sites for the coating material, thus increasing the vanadium ion exchange capacity. Meanwhile, the higher acidity helps to inhibit the active components from reacting with SO 2 The adsorption of SSZ-13 molecular sieve improves the sulfur resistance of the catalyst; the good hydrothermal stability of the molecular sieve also improves the long-term service life of the catalyst in industrial applications; at the same time, the modification of SSZ-13 molecular sieve produces more polymerized VO X and low-cost VO X , improve low temperature activity;

[0050] SiO 2 The addition of catalyst can maintain the effective and close combination between the catalyst coating material and the catalyst carrier for a long time, extend the service life of the catalyst and reduce the cost of use.

[0051] In summary, the present invention has the following beneficial effects compared with the prior art:

[0052] The present invention adopts tungsten-doped (5%) anatase nano titanium dioxide. 3 Distributed to the surface of the material, the dispersion is more uniform. After mixing the titanium dioxide material, a layer of WO 3 , make WO 3 There is a gap in the thickness distribution on the surface of the mixed material, which increases the acid sites inside and on the surface of the mixed material, promotes the formation of V-O-W on the surface of the mixed material and increases V 5+ ratio, improve the low temperature performance, and broaden the catalyst activity range; the addition of zirconium inhibits V 2 O 5 Polymerization at high temperature improves the thermal stability of the catalyst and increases the vacant oxygen sites on the surface of the coating material, thus improving the resistance to SO in practical applications. 2 and H 2 O ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0054] Figure 1 This is a fresh performance diagram of the catalyst of the present invention;

[0055] Figure 2 This is a graph showing the aging performance of the catalyst of the present invention. DETAILED DESCRIPTION

[0056] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0057] In the present invention, the catalyst carrier is made of cordierite honeycomb ceramics with a honeycomb mesh of 46. The cylindrical dimensions are: radius: 25.4 mm to 550 mm, height: 25.4 mm to 200 mm, and the square dimensions are: length: 100 mm to 1000 mm, width: 100 mm to 1000 mm, and height: 50 mm to 300 mm.

[0058] Embodiment 1:

[0059] Preparation of supporting layer solution: SSZ-13 molecular sieve, alumina and glacial acetic acid were mixed in a mass ratio of 92:4:4, and mechanically ball milled for 0.1 h to 0.5 h to prepare supporting layer solution.

[0060] Preparation of coating material: Tungsten-doped (5%) anatase nano-titanium dioxide, titanium dioxide and SSZ-13 molecular sieve are mixed in a designed mass ratio of 4:5:1, and the mixture is mechanically ball-milled for 0.5 h to 1 h to obtain a coating material.

[0061] Prepare active component precursor solution: add platinum salt according to 3.7% of the total load of the carrier, add zirconium salt according to 3.7% of the total load, add tungsten salt according to 6.7% of the total load, dissolve and mix evenly, stir for 0.5h, adjust pH = 4.0; add citric acid, the added mass is 1.28 times that of V2O5, and then add ethanolamine, the added mass is 0.29 times that of V2O5; after stirring evenly, heat the solution to 80°C, keep stirring and keep warm for 3h; prepare active component precursor solution.

[0062] Preparation of catalyst slurry: Add the prepared coating material, the mass of which accounts for 53.6% of the total catalyst loading. After the insulation is completed, cool the mixed solution to room temperature, add 7.5% of the total loading silica sol, adjust the pH to 6.5, stir for 1 hour, and prepare catalyst slurry.

[0063] Preparation of catalyst: The ceramic carrier is used for coating. The supporting layer solution is evenly spread on the surface of the inner pores of the carrier by using vacuum negative pressure. After completion, the catalyst is dried at 110℃ for 0.5h and weighed to ensure that the residual material remains at 0.65g. The catalyst slurry is evenly spread on the surface of the inner pores of the carrier by using vacuum negative pressure again. After completion, the catalyst is dried at 110℃ for 0.5h and weighed to ensure that the residual material remains at 1.98g. The coated catalyst is then calcined at 500℃ for 1h to ensure that the total residual dry mass is 2.63g.

[0064] Example 2: In this example, the preparation process of the catalyst is the same as that of Example 1, with the only difference being that the mass ratio of tungsten-doped (5%) anatase-type nano-titanium dioxide, anatase-type nano-titanium dioxide and SSZ-13 molecular sieve is 1:8:1.

[0065] Example 3: In this example, the preparation process of the catalyst is the same as that of Example 1, with the only difference being that the mass ratio of tungsten-doped (5%) anatase-type nano-titanium dioxide, anatase-type nano-titanium dioxide and SSZ-13 molecular sieve is 4:6:0.

[0066] Example 4: In this example, the preparation process of the catalyst is the same as that of Example 1, with the only difference being that the mass ratio of tungsten-doped (5%) anatase-type nano-titanium dioxide, anatase-type nano-titanium dioxide and SSZ-13 molecular sieve is 0:90:1.

[0067] Example 5: In this example, the preparation process of the catalyst is the same as that of Example 1, with the only difference being that the mass ratio of tungsten-doped (5%) anatase-type nano-titanium dioxide, anatase-type nano-titanium dioxide and SSZ-13 molecular sieve is 0:1:0.

[0068] In Examples 1 and 2 to 5, the types of transition metals and binders are the same, but the proportions of tungsten-doped (5%) anatase-type nano-titanium dioxide, titanium dioxide and SSZ-13 molecular sieve are different. The purpose is to compare the differences in fresh performance and aged performance of catalysts with different proportions in the mixture.

[0069] Example 6: In this example, the preparation process of the catalyst is the same as that of Example 1, the only difference being that no tungsten salt or zirconium salt is added and only vanadium salt is used.

[0070] Example 7: In this example, the preparation process of the catalyst is the same as that of Example 1, the only difference being that no zirconium salt is added, and only vanadium salt and tungsten salt are used.

[0071] Example 8: In this example, the preparation process of the catalyst is the same as that of Example 1, with the only difference being that the zirconium salt is replaced with a cobalt salt, the proportion remains unchanged, and only the type is changed.

[0072] Example 9: In this example, the preparation process of the catalyst is the same as that of Example 1, with the only difference being that ammonium salt is replaced by cobalt salt, zirconium is replaced by cerium salt, and cerium acetate is replaced by cerium acetate. The proportions remain unchanged, only the types are changed.

[0073] In Examples 1 and 6 to 9, the titanium oxide mixtures have the same ratio of titanium monoxide, anatase nano-titanium dioxide, and titanium trioxide, but different types of transition metals, in order to compare the differences in fresh performance and aged performance of catalysts with different transition metal types.

[0074] By comparing the freshness performance and aging performance test results of Example 1 and Examples 2 to 5, as shown in FIG. Figure 1 , Figure 2 As shown, the results show that:

[0075] The fresh performance of Example 1 is improved by 5%-10% compared with the control, and the aged performance is improved by 5%-15% compared with the control. Thanks to the three mixed in proportion, the active components are evenly dispersed on the surface and pores of the coating material in the liquid environment, providing more attachment sites for the active components, increasing the contact area between the active substance and the reactant, and improving the catalyst performance. The tungsten brought by the tungsten doping cooperates with the additional tungsten added to increase the internal and surface acid sites. 2 The surface forms V-O-W and increases V 5+ ratio, improve the low temperature performance, and broaden the catalyst activity range; the addition of zirconium inhibits V 2 O 5 Polymerization at high temperature improves the thermal stability of the catalyst and increases the vacant oxygen sites on the surface of the coating material, thereby improving the resistance to H in practical applications. 2 O capacity; at the same time, the addition of SSZ-13 molecular sieve, with its high specific surface area and acidity, provides more surface B acid sites and L acid sites for the coating material, increases the vanadium ion exchange capacity and improves the catalyst performance; the good hydrothermal stability of the molecular sieve also increases the long-term service life of the catalyst in industrial applications;

[0076] By comparing the freshness performance and aging performance test results of Example 1 and Examples 6 to 9, as shown in FIG. Figure 1 , Figure 2 As shown, the results show that:

[0077] The vanadium, tungsten and zirconium composite oxides formed after calcination can effectively inhibit the displacement and agglomeration of platinum, maintain the high dispersion, stable particle size and electronic state of vanadium; the appropriate ratio of vanadium, tungsten and zirconium can give full play to the performance of the oxides, enhance the interaction between active components, improve its own stability and realize a long service life of the catalyst.

[0078] The catalyst performance test method is as follows:

[0079] The concentration of exhaust gas before and after passing through the catalyst is detected by a chromatograph to determine the ignition temperature and conversion efficiency temperature; the catalyst is aged in a conditional atmosphere and tested in the same atmosphere to determine the ignition temperature and conversion efficiency after aging. The test boundaries are as follows:

[0080] Test atmosphere NOX=500ppm, NH3=500ppm, O2=8%, H2O=8%, N2 balance, ANR=1.0 Aging atmosphere 650℃@100h, 20%H2O, 1Wh-1 Test airspeed 10000h-1 Test temperature 200℃、250℃、300℃、400℃、450℃ Test Status Steady State

[0081] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A low space velocity SCR catalyst, characterized in that: comprising a coating layer and a supporting layer, wherein The coating comprises: The coating material is a mixture of tungsten-doped (5%) anatase nano-titanium dioxide, titanium dioxide and SSZ-13 molecular sieve, with a content of 56.1wt% to 75.6wt% of the total loading; An active component, a mixture of V2O5 and transition metal oxides, wherein the V2O5 content is 3.0wt% to 7.0wt% of the total loading, and the precursor is a vanadium salt; the transition metal oxide content is 6.8wt% to 15.3wt% of the total loading, and the precursor is a transition metal salt; Binder, silicon dioxide, the precursor is silica sol, the content is 4.2wt% to 9.0wt% of the total load; The support layer comprises SSZ-13 molecular sieve, and the support layer accounts for 10.0 wt% to 15.0 wt% of the total loading.

2. The method for preparing a low space velocity SCR catalyst according to claim 1, characterized in that: The support layer comprises SSZ-13 molecular sieve and alumina, wherein the SSZ-13 molecular sieve accounts for 90.0wt% to 100.0wt% and the alumina layer accounts for 0.0wt% to 10.0wt%; In the coating material, the tungsten-doped (5%) anatase nano-titanium dioxide accounts for 0.0wt% to 40.0wt%, the titanium dioxide accounts for 50.0wt% to 90.0wt%, and the SSZ-13 molecular sieve accounts for 0.0wt% to 10.0wt%.

3. A method for preparing a low space velocity SCR catalyst, characterized in that: The following steps are involved: preparing a supporting layer solution and a coating material; Mixing and dissolving vanadium salt and transition metal salt to prepare catalyst slurry; preparing a catalyst carrier, coating the catalyst carrier with a supporting layer solution, and drying the catalyst carrier with the supporting layer solution; After drying the catalyst carrier with the supporting layer solution, coating the catalyst slurry on the catalyst carrier, and drying the catalyst carrier with the catalyst slurry; The catalyst carrier with the catalyst slurry after calcination and drying obtains the low space velocity SCR catalyst as claimed in claim 1 or 2.

4. The method for preparing a low space velocity SCR catalyst according to claim 3, characterized in that: Spreading the supporting layer solution comprises the following steps: Evenly spread the support layer solution on the catalyst carrier, and shake the catalyst carrier until the support layer solution flows into the pores of the catalyst carrier; Applying negative pressure airflow or positive pressure airflow to the catalyst carrier until the support layer solution is evenly spread in the pores of the catalyst carrier; The catalyst carrier with the supporting layer solution is dried.

5. The method for preparing a low space velocity SCR catalyst according to claim 3, characterized in that: Spreading the catalyst slurry comprises the following steps: Evenly spread the support layer solution on the catalyst carrier, and shake the catalyst carrier until the support layer solution flows into the pores of the catalyst carrier; Applying negative pressure airflow or positive pressure airflow to the catalyst carrier until the support layer solution is evenly spread in the pores of the catalyst carrier; The catalyst carrier with the catalyst slurry is dried.

6. The method for preparing a low space velocity SCR catalyst according to claim 3, characterized in that: The preparation of the supporting layer solution comprises the following steps: The SSZ-13 molecular sieve, alumina and glacial acetic acid are mixed in a mass ratio to obtain a support layer mixture, wherein: SSZ-13 molecular sieve accounts for 86wt% to 92wt%, alumina accounts for 0wt% to 7wt%, and glacial acetic acid accounts for 0wt% to 7wt%; Grinding the support layer mixture by mechanical ball milling for 0.1 h to 0.5 h; A supporting layer solution is prepared.

7. The method for preparing a low space velocity SCR catalyst according to claim 3, characterized in that: The preparation of the coating material comprises the following steps: Mixing tungsten-doped (5%) anatase nano-titanium dioxide, titanium dioxide and SSZ-13 molecular sieve according to a mass ratio to obtain a coating mixture, wherein the tungsten-doped (5%) anatase nano-titanium dioxide accounts for 0.0wt% to 40.0wt%, the titanium dioxide accounts for 50.0wt% to 90.0wt%, and the SSZ-13 molecular sieve accounts for 0.0wt% to 10.0wt%; Grinding the coating mixture by mechanical ball milling for 0.1 h to 0.5 h; Made into coating material.

8. The method for preparing a low space velocity SCR catalyst according to claim 3, characterized in that: The catalyst slurry preparation comprises the following steps: Mix and dissolve the vanadium salt and transition metal salt, stir for 0.5h to 1h, mix evenly, and adjust the pH to 3 to 6; Add additives, raise the temperature to 60℃~90℃, keep warm for 0.5h~1h, then add coating materials and additives, raise the temperature to 60℃~90℃, keep stirring and keep warm for 1h~3h. After the insulation is completed, cool the solution to room temperature; Add a binder, adjust the pH to 6-8, and stir for 3-5 hours to prepare a catalyst slurry.

9. The method for preparing a low space velocity SCR catalyst according to claim 8, characterized in that: The additive includes one or a combination of any two or more of ethylene glycol, glucose, sodium borohydride, ascorbic acid, and citric acid, and the content thereof is 1 to 3 times that of V2O5; The auxiliary agent includes one or a combination of any two or more of hydrochloric acid, nitric acid, acetic acid, oxalic acid, ethylenediamine, and ethanolamine, and its content is 0.207 to 0.345 times that of V2O5; The binder is silica sol, which accounts for 4.2wt% to 9.0wt% of the total load.

10. The method for preparing a low space velocity SCR catalyst according to claim 3, characterized in that: When the catalyst carrier with the catalyst slurry is calcined and dried, the drying temperature is 110° C. to 150° C., the drying time is 0.5 h to 2 h, the calcination temperature is 450° C. to 550° C., and the calcination time is 1 h to 3 h.

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