A method for preparing a cesium-rubidium salt synergistically modified sulfur dioxide oxidation catalyst

Abstract

This application provides a method for preparing a cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst. This method involves constructing a rubidium-containing neutralizing solution and a neutralizing solution containing a cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst during the catalyst preparation process. Different alkali metal sulfates are introduced sequentially during the support impregnation process, and the participation of silicates in the neutralization stage regulates the distribution of alkali metal promoters within the catalyst particles. This improves the effective utilization efficiency of the active components and promoters in the catalyst, promotes the adsorption and mass transfer processes of reactants on the catalyst surface, and enhances the activity of the sulfur dioxide oxidation reaction.

Description

Technical Field

[0001] This application relates to the field of sulfur dioxide oxidation catalyst technology, specifically to a method for preparing a cesium-rubidium salt synergistically modified sulfur dioxide oxidation catalyst. Background Technology

[0002] The oxidation of sulfur dioxide is a crucial step in sulfuric acid production, typically achieved using vanadium-based catalysts with vanadium pentoxide as the main active component. These catalysts generally consist of an active component, promoters, and a support. The introduction of promoters significantly influences the acid-base properties of the catalyst surface, the molten salt state, and the adsorption and diffusion behavior of reactant gases on the catalyst surface, thus affecting the catalyst's reactivity to some extent. Therefore, in practical industrial applications, alkali metal sulfates are often introduced as promoters into vanadium-based catalysts to improve their catalytic performance.

[0003] In existing technologies, commonly used alkali metal sulfates include potassium sulfate, rubidium sulfate, and cesium sulfate. These alkali metal salts can form a certain molten salt phase in the catalyst system, affecting the mass transfer of reactant molecules and the surface reaction process of active components, thereby promoting the oxidation of sulfur dioxide to a certain extent. However, different alkali metal sulfates have different physicochemical properties in the catalyst, and their effects on the reaction process also vary. For example, some alkali metal sulfates have good fluidity and surface wetting ability at lower temperatures, but poor stability at high temperatures; while other alkali metal sulfates, although having good thermal stability, have relatively limited promoting effect on reaction activity. Therefore, in practical applications, single alkali metal sulfate promoters often cannot fully exert their role in promoting reaction activity in the catalyst system.

[0004] Furthermore, in existing catalyst preparation processes, alkali metal sulfates are typically introduced into the catalyst system through co-mixing or impregnation with catalyst feedstocks. Their distribution within the catalyst particles often lacks effective control, resulting in an uneven or random distribution both inside and on the surface of the particles. During the reaction, this distribution can lead to the migration or localized enrichment of some promoters at high temperatures, thus affecting the effective utilization of active components and the adsorption and diffusion behavior of reactants on the catalyst surface, ultimately limiting further enhancement of catalyst activity.

[0005] Therefore, how to further improve the reaction activity of existing vanadium-based sulfur dioxide oxidation catalyst systems remains a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] This application provides a method for preparing a cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst. By optimizing the catalyst promoter system and its introduction method, the technical problems of limited catalytic promotion effect of alkali metal sulfate promoters and the need to further improve catalyst activity in existing sulfur dioxide oxidation catalysts are solved, thereby achieving an improvement in the activity of sulfur dioxide oxidation reaction.

[0007] In a first aspect, this application provides a method for preparing a cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst, comprising the following steps:

[0008] S1: Provide 100 parts diatomaceous earth, 5-8 parts fumed silica, 8-11 parts sodium sulfate, 4-8 parts forming agent, 10-15 parts vanadium pentoxide, 20-30 parts caustic alkali, 4-8 parts silicate, 0.1-50 parts rubidium sulfate, and 0.1-50 parts cesium sulfate as raw materials;

[0009] S2: Dissolve vanadium pentoxide and caustic alkali in water to obtain vanadium water;

[0010] S3: Add some silicate and rubidium sulfate to a portion of vanadium water, then add sulfuric acid to adjust the pH to 2-6 to obtain a rubidium-containing neutralized solution;

[0011] S4: Add the remaining silicate and cesium sulfate to the remaining vanadium water, and then add sulfuric acid to adjust the pH to 2-6 to obtain a cesium-containing neutralized solution;

[0012] S5: Mix diatomaceous earth, fumed silica, sodium sulfate and molding agent and add to rubidium-containing neutralizing liquid, so that the rubidium-containing neutralizing liquid wets the carrier to obtain rubidium-containing wet material;

[0013] S6: Add cesium-containing neutralizing liquid to the rubidium-containing wet material, and let the cesium-containing neutralizing liquid wett the carrier to obtain cesium-rubidium-containing wet material;

[0014] S7: After the cesium-rubidium-containing wet material is kneaded under negative pressure, it is dried, calcined and activated to obtain a cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst.

[0015] According to this application, by constructing rubidium-containing neutralizing liquid and cesium-containing neutralizing liquid respectively during the catalyst preparation process, and introducing different alkali metal sulfates in a sequential wetting manner during the support wetting process, while cooperating with the participation of silicates in the neutralization stage, the distribution state of alkali metal promoters in the catalyst particles can be regulated, thereby improving the effective utilization efficiency of active components and promoters in the catalyst, promoting the adsorption and mass transfer process of reactants on the catalyst surface, and realizing the enhancement of sulfur dioxide oxidation reaction activity.

[0016] Specifically, in this application, vanadium pentoxide is dissolved in a caustic alkali to form vanadium water, allowing the active component to participate in the subsequent neutralization reaction in solution form, which is beneficial for the uniform dispersion of the active component in the catalyst system. Simultaneously, silicates are introduced during the neutralization process, and the pH of the system is adjusted to 2-6 under acidic conditions, enabling the silicates to undergo an acidification reaction to form silicic acid, gradually forming a dispersed silica sol structure. This silica sol can enter the pores of the support along with the neutralization solution during subsequent impregnation, forming preliminary deposits on the support surface and pore walls, thereby limiting the migration of alkali metal ions in the system and reducing the migration of alkali metal sulfates in the wet material.

[0017] Based on this, this application prepares rubidium-containing neutralizing solutions and cesium-containing neutralizing solutions respectively. During the carrier impregnation process, the rubidium-containing neutralizing solution is added first, followed by the cesium-containing neutralizing solution. This allows the rubidium-containing neutralizing solution to more easily penetrate the pore structure formed by diatomaceous earth and silica under capillary action, while the subsequently added cesium-containing neutralizing solution is more easily distributed in the outer region of the catalyst particles. Simultaneously, since silica sol has a certain restrictive effect on alkali metal ions in the system, it can inhibit the migration of the rubidium-containing components that first enter the pores to a certain extent. This is beneficial for forming an additive distribution structure in the catalyst particles where rubidium salts are mainly distributed internally and cesium salts are mainly distributed in the outer region.

[0018] In this distribution structure, the outer region of the catalyst particles is rich in cesium salts. Cesium salts have a low melting point and a strong ability to form molten salts, making it easier to form a fluid active molten salt phase on the catalyst surface during the reaction. This promotes the adsorption and activation of sulfur dioxide on the catalyst surface and improves the efficiency of reactant diffusion into the catalyst interior. Meanwhile, the rubidium salts located in the inner region of the catalyst have good thermal stability and can maintain a relatively stable molten salt structure during the reaction, which is beneficial for maintaining the stability of the active phase inside the catalyst. This outside-to-inside promoter distribution structure creates a more favorable active environment for the reaction within the catalyst particles, allowing reactants to gradually participate in the catalytic reaction as they enter the catalyst interior, thereby improving the utilization efficiency of the active components.

[0019] Furthermore, during the subsequent drying and calcination activation process, the silicate-formed silicon-oxygen structure can further stabilize the distribution of promoters inside the catalyst, reduce the possibility of migration or redistribution of alkali metal sulfates under high temperature conditions, and maintain the distribution structure of cesium salts and rubidium salts in the catalyst particles, thereby maintaining a stable active structure during the use of the catalyst.

[0020] Meanwhile, in terms of catalyst structure, diatomaceous earth and silica can jointly construct a porous support framework with a high specific surface area and abundant pore structure, providing good diffusion channels for reactant gases. Meanwhile, sodium sulfate, as a sulfate component, participates in the formation of the molten salt system in the catalyst, and can regulate the composition and flowability of the molten salt phase during the reaction, enabling the active components to form a stable and continuous active environment on the support surface. The above structures, in conjunction with the distribution structure of the additives, enable the catalyst to form an active system more conducive to the oxidation of sulfur dioxide during the reaction, thereby further enhancing the catalyst's reactivity.

[0021] In some embodiments, step S1 includes:

[0022] The raw materials include 100 parts diatomaceous earth, 5-8 parts silica, 8-11 parts sodium sulfate, 4-8 parts forming agent, 10-15 parts vanadium pentoxide, 20-30 parts caustic alkali, 4-8 parts silicate, 2-6 parts rubidium sulfate, and 2-6 parts cesium sulfate; the mass ratio of rubidium sulfate to cesium sulfate is 4:6 to 6:4.

[0023] In some of the above embodiments, by controlling the addition of rubidium sulfate and cesium sulfate to 2-6 parts, and further limiting their mass ratio to the range of 4:6-6:4, the synergistic effect of the two alkali metal sulfates in the catalyst can be improved. On the one hand, within this ratio range, cesium salt can form a molten salt phase with good fluidity in the outer region of the catalyst, which is beneficial to improving the adsorption and activation capacity of sulfur dioxide on the catalyst surface, thereby promoting the entry of reactant gases into the interior of the catalyst particles. On the other hand, rubidium salt can maintain a relatively stable molten salt structure in the inner region of the catalyst, which is beneficial to maintaining the stability of the active phase inside the catalyst, allowing the reaction to continue inside the catalyst. Through the combination of the two alkali metal salts within this ratio range, a more suitable active environment can be formed in the catalyst particles, ensuring that the reactants maintain a highly efficient catalytic reaction from contact to entry into the interior of the catalyst, thereby improving the utilization efficiency of the active components and enhancing the overall reaction activity of the catalyst.

[0024] In some implementations, step S2 includes:

[0025] Vanadium pentoxide and caustic alkali are dissolved in 50-80 parts of water to obtain vanadium water.

[0026] In some of the above embodiments, by dissolving vanadium pentoxide and caustic alkali in an appropriate amount of water, the active components can be fully dissolved and a relatively uniform vanadium-water system can be formed, which is conducive to the smooth progress of the subsequent neutralization reaction and the uniform dispersion of the active components in the catalyst preparation process, thereby improving the stability of the catalyst preparation process.

[0027] In some embodiments, steps S3 and S4 include:

[0028] Take 40% to 60% of the vanadium water from step S2, add silicate and rubidium sulfate accounting for 40% to 60% of the total silicate mass, dissolve, and then add sulfuric acid to adjust the pH of the system to 2 to 6 to obtain a rubidium-containing neutralized solution.

[0029] Add the remaining silicate and cesium sulfate to the remaining vanadium water, dissolve them, and then add sulfuric acid to adjust the pH of the system to 2-6 to obtain a cesium-containing neutralized solution.

[0030] In some of the above embodiments, by dividing the vanadium solution into two parts at a ratio of 40% to 60%, and adding silicates to the two neutralization solutions at a ratio of 40% to 60% respectively, the active components and silicate content in the rubidium-containing neutralization solution and the cesium-containing neutralization solution can be kept in a relatively balanced state, which is conducive to the stable progress of the neutralization reaction. At the same time, the introduction of silicates during the neutralization process is beneficial to the formation of a structure in which the vanadium-containing components and silicates work together in the system, making it easier for alkali metal ions to be fixed on the surface or in the pores of the carrier during the loading stage, thereby reducing their migration in the wet material.

[0031] Under these conditions, the rubidium-containing neutralized liquid and the cesium-containing neutralized liquid formed can enter the carrier pores more uniformly during the subsequent impregnation process, and it is beneficial to form a differentiated distribution of the additives through stepwise impregnation. This provides conditions for achieving the controllable distribution of rubidium salts and cesium salts in the catalyst particles and helps to improve the stability of the catalyst preparation process.

[0032] In some implementations, step S5 includes:

[0033] After mixing diatomaceous earth, fumed silica, sodium sulfate and forming agent, add rubidium-containing neutralizing liquid and mix for 4-6 minutes to obtain rubidium-containing wet material.

[0034] In some of the above embodiments, by mixing the rubidium-containing neutralizing liquid with the carrier raw material, the rubidium-containing neutralizing liquid can be fully contacted between the carrier particles and more easily enter the pore structure formed by diatomite and silica under capillary action. This is beneficial to the loading and distribution of the rubidium-containing component inside the carrier pores, and provides conditions for the formation of a differentiated additive distribution structure when cesium-containing neutralizing liquid is subsequently introduced.

[0035] In some implementations, step S6 includes:

[0036] Add cesium-containing neutralizing liquid to the rubidium-containing wet material and mix for 2-4 minutes to obtain cesium-rubidium-containing wet material.

[0037] In some of the above embodiments, by adding a cesium-containing neutralizing liquid after the formation of the rubidium-containing wet material, the cesium-containing neutralizing liquid can be further dispersed in the support system that has already been partially impregnated with the rubidium-containing components, thus making it easier to distribute in the outer region of the catalyst particles. Simultaneously, since silicates are introduced during the neutralization stage, the silicon-oxygen structure formed by the silicates has a certain immobilizing effect on alkali metal ions, which can reduce the migration of the rubidium-containing components in the wet material to a certain extent, making them more stably distributed within the pores of the support. Under these conditions, the subsequently added cesium-containing components are more easily distributed on the surface or outer region of the catalyst particles, thereby facilitating the formation of an additive distribution structure with differentiated characteristics.

[0038] In some implementations, step S7 includes:

[0039] The cesium-rubidium-containing wet material is kneaded under negative pressure at 70-100℃ for 4-10 minutes, shaped and dried, and then calcined at 450-600℃ for 30-60 minutes to obtain a cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst.

[0040] In some of the above embodiments, negative pressure kneading at 70-100°C allows for thorough mixing of the components in the wet material and promotes the removal of moisture, thus facilitating the formation of a catalyst preform with a uniform structure. Subsequent molding and drying further stabilize the catalyst structure. Calcination and activation at 450-600°C allows the active components and additives to form a stable structure within the catalyst system. Simultaneously, the action of silicates further reduces the migration of alkali metal sulfates under high-temperature conditions, maintaining the distribution of cesium and rubidium salts within the catalyst particles. This helps maintain the active structure of the catalyst and enhances the catalytic activity of the sulfur dioxide oxidation reaction.

[0041] In some embodiments, the silica content of the diatomaceous earth is ≥85wt%. Based on the above embodiments, when the silica content in the diatomaceous earth is high, its structural stability and pore structure are better, which is conducive to the formation of a stable porous support framework, thereby facilitating the loading and dispersion of active components and additives in the catalyst in the support.

[0042] In some embodiments, the specific surface area of ​​the silica is 160-200 m². 2 / g. Based on the above embodiments, silica with a higher specific surface area can provide more surface sites and is beneficial for co-constructing a porous structure with a higher specific surface area with diatomaceous earth, thereby facilitating the dispersion of active components in the catalyst and the diffusion of reactant gases in the catalyst.

[0043] In some embodiments, the forming agent includes at least one of cellulose and methylcellulose. Based on the above embodiments, cellulose-based forming agents can provide good binding during the catalyst forming process, making it easier for the material to form a stable catalyst preform, thereby facilitating the stable progress of the catalyst forming process.

[0044] In some embodiments, the caustic alkali includes at least one of sodium hydroxide and potassium hydroxide. Based on the above embodiments, by using sodium hydroxide or potassium hydroxide as the caustic alkali, vanadium pentoxide can be more easily dissolved and a stable vanadium-water system can be formed, which is beneficial to the smooth progress of the subsequent neutralization reaction.

[0045] In some embodiments, the silicate includes at least one of sodium silicate and potassium silicate. Based on the above embodiments, silicates can participate in the formation of the system structure during the neutralization process and have a certain immobilization effect on alkali metal ions, thereby helping to reduce the migration of alkali metal sulfates during catalyst preparation and subsequent high-temperature use, and making the distribution of the promoter in the catalyst more stable.

[0046] Secondly, this application provides a cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst, which is prepared according to the preparation method described in any embodiment of the first aspect.

[0047] According to this application, by constructing rubidium-containing neutralizing solutions and cesium-containing neutralizing solutions separately during catalyst preparation, and introducing different alkali metal sulfates through stepwise impregnation, while simultaneously involving silicates in the neutralization stage, the distribution of alkali metal promoters within the catalyst particles is regulated. This results in a promoter distribution structure where rubidium salts are mainly distributed inside the catalyst particles, and cesium salts are mainly distributed in the outer layer of the catalyst particles. In this structure, the outer layer of the catalyst particles is rich in cesium salts, which facilitates the formation of a molten salt phase with good fluidity during the reaction, thereby promoting the adsorption and activation of sulfur dioxide on the catalyst surface. Meanwhile, the rubidium salts in the inner region of the catalyst help maintain the stability of the active phase inside the catalyst, allowing the reaction to continue within the catalyst.

[0048] Simultaneously, the silicates introduced during the neutralization process can gradually form a silica sol structure under acidic conditions. This silica sol can enter the pores of the support along with the neutralization liquid and gradually condense to form a stable silicon-oxygen structure during subsequent drying and calcination. This structure can restrict the migration of alkali metal sulfates within the catalyst, ensuring the stability of the aforementioned promoter distribution structure during catalyst use. Under these conditions, the catalyst can create a more favorable active environment for the oxidation of sulfur dioxide during the reaction, thereby enhancing the catalyst's reactivity.

[0049] Thirdly, this application provides the application of the cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst according to any embodiment of the second aspect in the catalytic oxidation of sulfur dioxide to prepare sulfur trioxide.

[0050] According to this application, by using the cesium-rubidium salt synergistic modification of the sulfur dioxide oxidation catalyst to carry out the sulfur dioxide oxidation reaction, the catalytic activity of the catalyst for the sulfur dioxide oxidation reaction can be improved, thereby improving the conversion efficiency of sulfur dioxide to sulfur trioxide.

[0051] Compared with the prior art, the beneficial effects of this application are at least as follows:

[0052] By constructing rubidium-containing and cesium-containing neutralizing solutions separately during catalyst preparation and introducing different alkali metal sulfates through stepwise impregnation, the distribution of rubidium and cesium salts within the catalyst particles can be regulated, thereby forming a promoter distribution structure favorable for the reaction. Simultaneously, the introduction of silicates during neutralization and the subsequent formation of stable silicon-oxygen structures can, to some extent, reduce the migration of alkali metal sulfates during catalyst preparation and use, resulting in a more stable promoter distribution. Through these synergistic effects, the utilization efficiency of the active components can be improved, and the mass transfer process of reactants within the catalyst can be enhanced, thereby increasing the catalytic activity of the sulfur dioxide oxidation reaction. Attached Figure Description

[0053] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0054] Figure 1 The XPS full spectrum of the cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst prepared in Example 1 of this application is shown.

[0055] Figure 2 The image shows the Cs3d scan in XPS for the cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst prepared in Example 1 of this application.

[0056] Figure 3 The image shows the Rd3d scan in XPS of the cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst prepared in Example 1 of this application. Detailed Implementation

[0057] The various embodiments or implementation schemes in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments.

[0058] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0059] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0060] In this specification, unless otherwise specified, "parts" refers to "parts by weight".

[0061] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0062] Diatomaceous earth: SiO2 content 89%, brand: Fengrun; grind and pass through a 100-mesh sieve for later use;

[0063] Silica: Specific surface area 189m² 2 / g, Brand: Yuanmeng Silicon Industry;

[0064] Sodium sulfate: 99.9% purity, 90 mesh particle size;

[0065] Cellulose: Average degree of polymerization 1500.

[0066] Example 1

[0067] Preparation of Cesium-Russium Salt Synergistic Modification of Sulfur Dioxide Oxidation Catalyst

[0068] (1) Raw material preparation

[0069] Prepare the following raw materials by weight: 100 parts diatomaceous earth, 6 parts fumed silica, 9 parts sodium sulfate, 5 parts cellulose, 12 parts vanadium pentoxide, 25 parts potassium hydroxide, 6 parts potassium silicate, 4 parts rubidium sulfate, and 4 parts cesium sulfate.

[0070] (2) Preparation of vanadium water

[0071] Add 60 parts of deionized water to a reaction vessel, and add 12 parts of vanadium pentoxide and 25 parts of potassium hydroxide in sequence under stirring. Stir and dissolve at 60°C for about 30 minutes to fully dissolve the vanadium pentoxide and form a homogeneous and stable solution to obtain vanadium water.

[0072] (3) Preparation of rubidium-containing neutralizing solution

[0073] Take 50 wt% of the vanadium water obtained in step (2), add 3 parts of potassium silicate (accounting for 50% of the total silicate content) and 4 parts of rubidium sulfate, and dissolve them completely under stirring. Then slowly add 50 wt% sulfuric acid solution to adjust the pH of the system to about 4, and continue stirring at 40°C for 20 min to obtain a rubidium-containing neutralized solution.

[0074] (4) Preparation of cesium-containing neutralized solution

[0075] Take the remaining 50 wt% vanadium solution, add the remaining 3 parts potassium silicate and 4 parts cesium sulfate, and dissolve them completely under stirring. Then slowly add 50 wt% sulfuric acid solution to adjust the pH of the system to about 4, and continue stirring at 40°C for 20 min to obtain a cesium-containing neutralized solution.

[0076] (5) Preparation of rubidium-containing wet materials

[0077] 100 parts of diatomaceous earth, 6 parts of silica, 9 parts of sodium sulfate and 5 parts of molding agent were added to a mixer for dry mixing for about 3 minutes to disperse the solid raw materials evenly. Then the rubidium-containing neutralizing liquid prepared in step (3) was added and the mixture was continued to be mixed in the mixer for about 5 minutes to obtain the rubidium-containing wet material.

[0078] (6) Preparation of wet materials containing cesium and rubidium

[0079] Add the cesium-containing neutralizing liquid prepared in step (4) to the above rubidium-containing wet material, and continue mixing in a mixer for about 3 minutes to obtain cesium-rubidium-containing wet material.

[0080] (7) Kneading and shaping

[0081] The aforementioned cesium-rubidium-containing wet material was fed into a kneader and kneaded under negative pressure at 90°C for approximately 6 minutes to further mix the material evenly and remove some moisture. The material was then extruded to obtain a wet catalyst preform.

[0082] (8) Drying and calcination

[0083] The obtained wet preform was dried in a 90℃ oven for about 6 hours to remove most of the moisture from the catalyst preform. Then, the dried catalyst was placed in a muffle furnace and calcined at 500℃ for 40 minutes to further stabilize the active components and additives in the catalyst, thus obtaining a cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst.

[0084] XPS full spectrum and Cs 3d and Rd 3d scans of the cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst are shown below. Figures 1-3 As shown, this indicates that cesium and rubidium are effectively loaded onto the catalyst.

[0085] Example 2

[0086] Preparation of Cesium-Russium Salt Synergistic Modification of Sulfur Dioxide Oxidation Catalyst

[0087] (1) Raw material preparation

[0088] Prepare the following raw materials by weight: 100 parts diatomaceous earth, 6 parts fumed silica, 9 parts sodium sulfate, 5 parts cellulose, 12 parts vanadium pentoxide, 25 parts potassium hydroxide, 6 parts potassium silicate, 2 parts rubidium sulfate, and 6 parts cesium sulfate.

[0089] (2) Preparation of vanadium water

[0090] Add 60 parts of deionized water to a reaction vessel, and add 12 parts of vanadium pentoxide and 25 parts of potassium hydroxide in sequence under stirring. Stir and dissolve at 60°C for about 30 minutes to fully dissolve the vanadium pentoxide and form a homogeneous and stable solution to obtain vanadium water.

[0091] (3) Preparation of rubidium-containing neutralizing solution

[0092] Take 50 wt% of the vanadium water obtained in step (2), add 3 parts of potassium silicate (accounting for 50% of the total silicate content) and 2 parts of rubidium sulfate, and let it dissolve completely under stirring. Then slowly add 50 wt% sulfuric acid solution to adjust the pH of the system to about 4, and continue stirring at 40°C for 20 min to obtain a rubidium-containing neutralized solution.

[0093] (4) Preparation of cesium-containing neutralized solution

[0094] Take the remaining 50 wt% vanadium solution, add the remaining 3 parts potassium silicate and 6 parts cesium sulfate, and dissolve them completely under stirring. Then slowly add 50 wt% sulfuric acid solution to adjust the pH of the system to about 4, and continue stirring at 40°C for 20 min to obtain a cesium-containing neutralized solution.

[0095] (5) Preparation of rubidium-containing wet materials

[0096] 100 parts of diatomaceous earth, 6 parts of silica, 9 parts of sodium sulfate and 5 parts of molding agent were added to a mixer for dry mixing for about 3 minutes to disperse the solid raw materials evenly. Then the rubidium-containing neutralizing liquid prepared in step (3) was added and the mixture was continued to be mixed in the mixer for about 5 minutes to obtain the rubidium-containing wet material.

[0097] (6) Preparation of wet materials containing cesium and rubidium

[0098] Add the cesium-containing neutralizing liquid prepared in step (4) to the above rubidium-containing wet material, and continue mixing in a mixer for about 3 minutes to obtain cesium-rubidium-containing wet material.

[0099] (7) Kneading and shaping

[0100] The aforementioned cesium-rubidium-containing wet material was fed into a kneader and kneaded under negative pressure at 90°C for approximately 6 minutes to further mix the material evenly and remove some moisture. The material was then extruded to obtain a wet catalyst preform.

[0101] (8) Drying and calcination

[0102] The obtained wet preform was dried in a 90℃ oven for about 6 hours to remove most of the moisture from the catalyst preform. Then, the dried catalyst was placed in a muffle furnace and calcined at 500℃ for 40 minutes to further stabilize the active components and additives in the catalyst, thus obtaining a cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst.

[0103] Example 3

[0104] Preparation of Cesium-Russium Salt Synergistic Modification of Sulfur Dioxide Oxidation Catalyst

[0105] (1) Raw material preparation

[0106] Prepare the following raw materials by weight: 100 parts diatomaceous earth, 6 parts fumed silica, 9 parts sodium sulfate, 5 parts cellulose, 12 parts vanadium pentoxide, 25 parts potassium hydroxide, 6 parts potassium silicate, 6 parts rubidium sulfate, and 2 parts cesium sulfate.

[0107] (2) Preparation of vanadium water

[0108] Add 60 parts of deionized water to a reaction vessel, and add 12 parts of vanadium pentoxide and 25 parts of potassium hydroxide in sequence under stirring. Stir and dissolve at 60°C for about 30 minutes to fully dissolve the vanadium pentoxide and form a homogeneous and stable solution to obtain vanadium water.

[0109] (3) Preparation of rubidium-containing neutralizing solution

[0110] Take 50 wt% of the vanadium water obtained in step (2), add 3 parts of potassium silicate (accounting for 50% of the total silicate content) and 6 parts of rubidium sulfate, and dissolve them completely under stirring. Then slowly add 50 wt% sulfuric acid solution to adjust the pH of the system to about 4, and continue stirring at 40°C for 20 min to obtain a rubidium-containing neutralized solution.

[0111] (4) Preparation of cesium-containing neutralized solution

[0112] Take the remaining 50 wt% vanadium solution, add the remaining 3 parts potassium silicate and 2 parts cesium sulfate, and dissolve them completely under stirring. Then slowly add 50 wt% sulfuric acid solution to adjust the pH of the system to about 4, and continue stirring at 40°C for 20 min to obtain a cesium-containing neutralized solution.

[0113] (5) Preparation of rubidium-containing wet materials

[0114] 100 parts of diatomaceous earth, 6 parts of silica, 9 parts of sodium sulfate and 5 parts of molding agent were added to a mixer for dry mixing for about 3 minutes to disperse the solid raw materials evenly. Then the rubidium-containing neutralizing liquid prepared in step (3) was added and the mixture was continued to be mixed in the mixer for about 5 minutes to obtain the rubidium-containing wet material.

[0115] (6) Preparation of wet materials containing cesium and rubidium

[0116] Add the cesium-containing neutralizing liquid prepared in step (4) to the above rubidium-containing wet material, and continue mixing in a mixer for about 3 minutes to obtain cesium-rubidium-containing wet material.

[0117] (7) Kneading and shaping

[0118] The aforementioned cesium-rubidium-containing wet material was fed into a kneader and kneaded under negative pressure at 90°C for approximately 6 minutes to further mix the material evenly and remove some moisture. The material was then extruded to obtain a wet catalyst preform.

[0119] (8) Drying and calcination

[0120] The obtained wet preform was dried in a 90℃ oven for about 6 hours to remove most of the moisture from the catalyst preform. Then, the dried catalyst was placed in a muffle furnace and calcined at 500℃ for 40 minutes to further stabilize the active components and additives in the catalyst, thus obtaining a cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst.

[0121] Comparative Example 1

[0122] Preparation of Cesium-Russium Salt Synergistic Modification of Sulfur Dioxide Oxidation Catalyst

[0123] (1) Raw material preparation

[0124] Prepare the following raw materials by weight: 100 parts diatomaceous earth, 6 parts fumed silica, 9 parts sodium sulfate, 5 parts cellulose, 12 parts vanadium pentoxide, 25 parts potassium hydroxide, 4 parts rubidium sulfate, and 4 parts cesium sulfate.

[0125] (2) Preparation of vanadium water

[0126] Add 60 parts of deionized water to a reaction vessel, and add 12 parts of vanadium pentoxide and 25 parts of potassium hydroxide in sequence under stirring. Stir and dissolve at 60°C for about 30 minutes to fully dissolve the vanadium pentoxide and form a homogeneous and stable solution to obtain vanadium water.

[0127] (3) Preparation of rubidium-containing neutralizing solution

[0128] Take 50 wt% of the vanadium water obtained in step (2), add 4 parts of rubidium sulfate, and let it dissolve completely under stirring. Then slowly add 50 wt% sulfuric acid solution to adjust the pH of the system to about 4, and continue stirring at 40°C for 20 min to obtain a rubidium-containing neutralized solution.

[0129] (4) Preparation of cesium-containing neutralized solution

[0130] Take the remaining 50wt% vanadium solution and add 4 parts of cesium sulfate, stirring until fully dissolved. Then, slowly add 50wt% sulfuric acid solution to adjust the pH of the system to approximately 4, and continue stirring at 40°C for 20 minutes to obtain a cesium-containing neutralized solution.

[0131] (5) Preparation of rubidium-containing wet materials

[0132] 100 parts of diatomaceous earth, 6 parts of silica, 9 parts of sodium sulfate and 5 parts of molding agent were added to a mixer for dry mixing for about 3 minutes to disperse the solid raw materials evenly. Then the rubidium-containing neutralizing liquid prepared in step (3) was added and the mixture was continued to be mixed in the mixer for about 5 minutes to obtain the rubidium-containing wet material.

[0133] (6) Preparation of wet materials containing cesium and rubidium

[0134] Add the cesium-containing neutralizing liquid prepared in step (4) to the above rubidium-containing wet material, and continue mixing in a mixer for about 3 minutes to obtain cesium-rubidium-containing wet material.

[0135] (7) Kneading and shaping

[0136] The aforementioned cesium-rubidium-containing wet material was fed into a kneader and kneaded under negative pressure at 90°C for approximately 6 minutes to further mix the material evenly and remove some moisture. The material was then extruded to obtain a wet catalyst preform.

[0137] (8) Drying and calcination

[0138] The obtained wet preform was dried in a 90℃ oven for about 6 hours to remove most of the moisture from the catalyst preform. Then, the dried catalyst was placed in a muffle furnace and calcined at 500℃ for 40 minutes to further stabilize the active components and additives in the catalyst, thus obtaining a cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst.

[0139] Comparative Example 2

[0140] Preparation of Cesium-Russium Salt Synergistic Modification of Sulfur Dioxide Oxidation Catalyst

[0141] (1) Raw material preparation

[0142] Prepare the following raw materials by weight: 100 parts diatomaceous earth, 6 parts fumed silica, 9 parts sodium sulfate, 5 parts cellulose, 12 parts vanadium pentoxide, 25 parts potassium hydroxide, 6 parts potassium silicate, 4 parts rubidium sulfate, and 4 parts cesium sulfate.

[0143] (2) Preparation of vanadium water

[0144] Add 60 parts of deionized water to a reaction vessel, and add 12 parts of vanadium pentoxide and 25 parts of potassium hydroxide in sequence under stirring. Stir and dissolve at 60°C for about 30 minutes to fully dissolve the vanadium pentoxide and form a homogeneous and stable solution to obtain vanadium water.

[0145] (3) Preparation of cesium-rubidium neutralized solution

[0146] Add 6 parts potassium silicate, 4 parts cesium sulfate, and 4 parts rubidium sulfate to the vanadium water obtained in step (2) and dissolve them completely under stirring. Then slowly add 50 wt% sulfuric acid solution to adjust the pH of the system to about 4, and continue stirring at 40°C for 20 min to obtain a cesium-rubidium neutralized solution.

[0147] (4) Preparation of wet materials containing cesium and rubidium

[0148] 100 parts diatomaceous earth, 6 parts silica, 9 parts sodium sulfate, and 5 parts molding agent were added to a mixer and dry-mixed for about 3 minutes to ensure uniform dispersion of the solid raw materials. Then, 50 wt% of the cesium-rubidium neutralizing solution prepared in step (3) was added, and mixing continued in the mixer for about 5 minutes.

[0149] Add the cesium-rubidium neutralized liquid prepared in the remaining step (3), and continue mixing in the mixer for about 3 minutes to obtain the cesium-rubidium wet material.

[0150] (5) Kneading and shaping

[0151] The aforementioned cesium-rubidium-containing wet material was fed into a kneader and kneaded under negative pressure at 90°C for approximately 6 minutes to further mix the material evenly and remove some moisture. The material was then extruded to obtain a wet catalyst preform.

[0152] (6) Drying and calcination

[0153] The obtained wet preform was dried in a 90℃ oven for about 6 hours to remove most of the moisture from the catalyst preform. Then, the dried catalyst was placed in a muffle furnace and calcined at 500℃ for 40 minutes to further stabilize the active components and additives in the catalyst, thus obtaining a cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst.

[0154] Comparative Example 3

[0155] Preparation of cesium salt modified sulfur dioxide oxidation catalyst

[0156] (1) Raw material preparation

[0157] Prepare the following raw materials by weight: 100 parts diatomaceous earth, 6 parts fumed silica, 9 parts sodium sulfate, 5 parts cellulose, 12 parts vanadium pentoxide, 25 parts potassium hydroxide, 6 parts potassium silicate, and 8 parts cesium sulfate.

[0158] (2) Preparation of vanadium water

[0159] Add 60 parts of deionized water to a reaction vessel, and add 12 parts of vanadium pentoxide and 25 parts of potassium hydroxide in sequence under stirring. Stir and dissolve at 60°C for about 30 minutes to fully dissolve the vanadium pentoxide and form a homogeneous and stable solution to obtain vanadium water.

[0160] (3) Preparation of cesium-containing neutralized solution

[0161] Add 6 parts potassium silicate and 8 parts cesium sulfate to the vanadium water obtained in step (2) and dissolve them completely under stirring. Then slowly add 50 wt% sulfuric acid solution to adjust the pH of the system to about 4, and continue stirring at 40°C for 20 min to obtain a cesium-containing neutralized solution.

[0162] (4) Preparation of cesium-containing wet materials

[0163] 100 parts diatomaceous earth, 6 parts silica, 9 parts sodium sulfate, and 5 parts molding agent were added to a mixer and dry-mixed for about 3 minutes to ensure uniform dispersion of the solid raw materials. Then, 50 wt% of the cesium-containing neutralizing solution prepared in step (3) was added, and mixing continued in the mixer for about 5 minutes.

[0164] Add the cesium-containing neutralized liquid prepared in the remaining step (3), and continue mixing in the mixer for about 3 minutes to obtain the cesium-containing wet material.

[0165] (5) Kneading and shaping

[0166] The cesium-containing wet material was fed into a kneader and kneaded under negative pressure at 90°C for about 6 minutes to further mix the material evenly and remove some moisture. The material was then extruded to obtain a wet catalyst preform.

[0167] (6) Drying and calcination

[0168] The obtained wet preform was dried in a 90℃ oven for about 6 hours to remove most of the moisture from the catalyst preform. Then, the dried catalyst was placed in a muffle furnace and calcined at 500℃ for 40 minutes to further stabilize the active components and additives in the catalyst, thus obtaining a cesium salt modified sulfur dioxide oxidation catalyst.

[0169] Comparative Example 4

[0170] Preparation of rubidium salt modified sulfur dioxide oxidation catalyst

[0171] (1) Raw material preparation

[0172] Prepare the following raw materials by weight: 100 parts diatomaceous earth, 6 parts fumed silica, 9 parts sodium sulfate, 5 parts cellulose, 12 parts vanadium pentoxide, 25 parts potassium hydroxide, 6 parts potassium silicate, and 8 parts rubidium sulfate.

[0173] (2) Preparation of vanadium water

[0174] Add 60 parts of deionized water to a reaction vessel, and add 12 parts of vanadium pentoxide and 25 parts of potassium hydroxide in sequence under stirring. Stir and dissolve at 60°C for about 30 minutes to fully dissolve the vanadium pentoxide and form a homogeneous and stable solution to obtain vanadium water.

[0175] (3) Preparation of rubidium-containing neutralizing solution

[0176] Add 6 parts potassium silicate and 8 parts rubidium sulfate to the vanadium water obtained in step (2) and dissolve them completely under stirring. Then slowly add 50 wt% sulfuric acid solution to adjust the pH of the system to about 4, and continue stirring at 40°C for 20 min to obtain a rubidium-containing neutralized solution.

[0177] (4) Preparation of rubidium-containing wet materials

[0178] Add 100 parts diatomaceous earth, 6 parts silica, 9 parts sodium sulfate, and 5 parts molding agent to a mixer and dry mix for about 3 minutes to ensure uniform dispersion of the solid raw materials. Then add 50 wt% of the rubidium-containing neutralizing solution prepared in step (3) and continue mixing in the mixer for about 5 minutes.

[0179] Add the rubidium-containing neutralized liquid prepared in the remaining step (3), and continue mixing in the mixer for about 3 minutes to obtain the rubidium-containing wet material.

[0180] (5) Kneading and shaping

[0181] The aforementioned rubidium-containing wet material was fed into a kneader and kneaded under negative pressure at 90°C for approximately 6 minutes to further mix the material evenly and remove some moisture. The material was then extruded to obtain a wet catalyst preform.

[0182] (6) Drying and calcination

[0183] The obtained wet preform was dried in a 90℃ oven for about 6 hours to remove most of the moisture from the catalyst preform. Then the dried catalyst was placed in a muffle furnace and calcined at 500℃ for 40 minutes to further stabilize the active components and additives in the catalyst, thus obtaining a rubidium salt modified sulfur dioxide oxidation catalyst.

[0184] Test section

[0185] Sample preparation: The sulfur dioxide oxidation catalysts prepared in Examples 1-3 and Comparative Examples 1-4 were processed into particles with flattened ends and a length of 6mm-7mm, with 40 particles per group.

[0186] Activity Testing: The activity of the above samples was tested according to the methods specified in the Chinese chemical industry standard "HG / T 2089-2014 Experimental Method for Activity of Catalysts for the Oxidation of Sulfur Dioxide to Sulfuric Acid". The solid catalyst was loaded into the reactor, and after ensuring no air leakage, the switch was turned on to conduct the experiment. The temperature was initially increased at a rate of 3°C per minute. After 60 minutes, dry air was introduced, and the space velocity was controlled at approximately 3600 h⁻¹. -1 After another 45 minutes, high-purity sulfur dioxide was introduced, controlling the sulfur dioxide volume fraction to approximately 10%. The temperature was then increased to 600℃ at a rate of 3℃ per minute, and subjected to heat treatment at 600℃ for 5 hours. After reaching the heat treatment time, the temperature was decreased to the activation temperature of 350℃ at a rate of 200℃ / h, and stabilized for 1 hour. The concentrations of SO2 at the inlet and outlet were measured using iodometric titration at 350℃, and the SO2 conversion rate (E) at 350℃ was calculated using the following formula: φ1 is the SO2 inlet volume fraction, and φ2 is the SO2 outlet volume fraction. The experimental results are shown in Table 1.

[0187]

[0188] Table 1

[0189]

[0190] According to Table 1, each embodiment exhibits higher catalytic activity compared to Comparative Examples 1-4, indicating that the preparation method provided in this application can effectively improve the catalytic activity of the sulfur dioxide oxidation catalyst. The possible reason is that by preparing rubidium-containing neutralizing solutions and cesium-containing neutralizing solutions respectively and sequentially wetting the support, the distribution state of rubidium salts and cesium salts in the catalyst particles is regulated. At the same time, combined with the fixation effect of the silica sol structure formed by silicates during the neutralization process on alkali metal ions, the migration of promoters in the catalyst can be reduced to a certain extent, so that the catalyst forms a more stable and active structure that is conducive to the reaction.

[0191] In Comparative Example 1, although rubidium-containing neutralizing liquid and cesium-containing neutralizing liquid were added in steps, no silicate was added to the system. Alkali metal sulfates were more likely to migrate during catalyst preparation and subsequent calcination, resulting in poor distribution stability of rubidium and cesium salts in the catalyst, leading to lower catalytic activity than in Examples 1-3.

[0192] In Comparative Example 2, although silicates were added, cesium sulfate and rubidium sulfate were added to the same neutralization solution at the same time, so that the two alkali metal salts were introduced into the support in a basically the same way, making it difficult to form an additive distribution structure with different characteristics, thereby weakening the synergistic effect between the additives. Therefore, its catalytic activity was still lower than that of Examples 1-3.

[0193] In Comparative Example 3, only cesium sulfate was used as a modifying agent. Although cesium salt can promote the oxidation reaction of sulfur dioxide to a certain extent, the lack of synergistic effect of rubidium salt makes the stability of the active phase inside the catalyst relatively weak. Therefore, its catalytic activity is lower than that of the example containing both cesium salt and rubidium salt.

[0194] In Comparative Example 4, only rubidium sulfate was used as a modifier. Although rubidium salt can improve the stability of the catalyst to some extent, its promoting effect on the oxidation reaction of sulfur dioxide is relatively limited, and it lacks the active environment for the formation of cesium salt, so its catalytic activity is further reduced.

[0195] As shown in Examples 1-3, the ratio of cesium sulfate to rubidium sulfate has a certain influence on the catalytic activity of the catalyst. In Example 1, the amounts of cesium sulfate and rubidium sulfate were the same, and the catalyst exhibited the highest catalytic activity. However, in Examples 2 and 3, the catalytic activity decreased when the ratio of the two alkali metal salts shifted. This indicates that simultaneously introducing cesium sulfate and rubidium sulfate within a certain ratio range can better leverage their synergistic effect, thereby increasing the catalytic activity of the catalyst for the oxidation of sulfur dioxide.

[0196] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing a cesium-rubidium salt synergistically modified sulfur dioxide oxidation catalyst, characterized in that, Includes the following steps: S1: Provide 100 parts diatomaceous earth, 5-8 parts fumed silica, 8-11 parts sodium sulfate, 4-8 parts forming agent, 10-15 parts vanadium pentoxide, 20-30 parts caustic alkali, 4-8 parts silicate, 0.1-50 parts rubidium sulfate, and 0.1-50 parts cesium sulfate as raw materials; S2: Dissolve vanadium pentoxide and caustic alkali in water to obtain vanadium water; S3: Add some silicate and rubidium sulfate to a portion of vanadium water, then add sulfuric acid to adjust the pH to 2-6 to obtain a rubidium-containing neutralized solution; S4: Add the remaining silicate and cesium sulfate to the remaining vanadium water, and then add sulfuric acid to adjust the pH to 2-6 to obtain a cesium-containing neutralized solution; S5: Mix diatomaceous earth, fumed silica, sodium sulfate and molding agent and add to rubidium-containing neutralizing liquid, so that the rubidium-containing neutralizing liquid wets the carrier to obtain rubidium-containing wet material; S6: Add cesium-containing neutralizing liquid to the rubidium-containing wet material, and let the cesium-containing neutralizing liquid wett the carrier to obtain cesium-rubidium-containing wet material; S7: After the cesium-rubidium-containing wet material is kneaded under negative pressure, it is dried, calcined and activated to obtain a cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst.

2. The preparation method according to claim 1, characterized in that, Step S1 includes: The raw materials include 100 parts diatomaceous earth, 5-8 parts silica, 8-11 parts sodium sulfate, 4-8 parts forming agent, 10-15 parts vanadium pentoxide, 20-30 parts caustic alkali, 4-8 parts silicate, 2-6 parts rubidium sulfate, and 2-6 parts cesium sulfate; the mass ratio of rubidium sulfate to cesium sulfate is 4:6 to 6:

4.

3. The preparation method according to claim 1, characterized in that, Step S2 includes: Vanadium pentoxide and caustic alkali are dissolved in 50-80 parts of water to obtain vanadium water.

4. The preparation method according to claim 1, characterized in that, Steps S3 and S4 include: Take 40% to 60% of the vanadium water from step S2, add silicate and rubidium sulfate accounting for 40% to 60% of the total silicate mass, dissolve, and then add sulfuric acid to adjust the pH of the system to 2 to 6 to obtain a rubidium-containing neutralized solution. Add the remaining silicate and cesium sulfate to the remaining vanadium water, dissolve them, and then add sulfuric acid to adjust the pH of the system to 2-6 to obtain a cesium-containing neutralized solution.

5. The preparation method according to claim 1, characterized in that, Step S5 includes: After mixing diatomaceous earth, fumed silica, sodium sulfate and forming agent, add rubidium-containing neutralizing liquid and mix for 4-6 minutes to obtain rubidium-containing wet material.

6. The preparation method according to claim 5, characterized in that, Step S6 includes: Add cesium-containing neutralizing liquid to the rubidium-containing wet material and mix for 2-4 minutes to obtain cesium-rubidium-containing wet material.

7. The preparation method according to claim 1, characterized in that, Step S7 includes: The cesium-rubidium-containing wet material is kneaded under negative pressure at 70-100℃ for 4-10 minutes, shaped and dried, and then calcined at 450-600℃ for 30-60 minutes to obtain a cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst.

8. The preparation method according to any one of claims 1 to 7, characterized in that, The preparation method satisfies at least one of the following conditions: (1) The silica content of the diatomaceous earth is ≥85wt%; (2) The specific surface area of ​​the silica is 160~200m². 2 / g; (3) The molding agent includes at least one of cellulose and methylcellulose; (4) The caustic alkali includes at least one of sodium hydroxide and potassium hydroxide; (5) The silicate includes at least one of sodium silicate and potassium silicate.

9. A cesium-rubidium salt synergistic modification catalyst for sulfur dioxide oxidation, characterized in that, It is prepared according to any one of claims 1 to 8.

10. The application of the cesium-rubidium salt synergistic modified sulfur dioxide oxidation catalyst according to claim 9 in the catalytic oxidation of sulfur dioxide to prepare sulfur trioxide.

Images