A vanadium-based catalyst for converting sulfur dioxide to sulfur trioxide by cracking waste acid, its preparation method and application

Abstract

This invention relates to the field of catalytic materials, specifically to a vanadium-based catalyst for the conversion of sulfur dioxide to sulfur trioxide in waste acid cracking, its preparation method, and its application. The vanadium-based catalyst comprises an active phase supported on a carrier, the active phase including a main active component and a co-active component; the main active component is vanadium oxide; and the composite carrier is macroporous oxide-modified diatomaceous earth. The vanadium-based catalyst prepared by this invention exhibits excellent catalytic performance and compressive strength when used in waste acid cracking processes to catalyze the conversion of sulfur dioxide to sulfur trioxide.

Description

Technical Field

[0001] This invention relates to the field of catalytic materials, specifically to a vanadium-based catalyst for converting sulfur dioxide into sulfur trioxide by cracking waste acid, its preparation method, and its application. Background Technology

[0002] Sulfuric acid is a widely used industrial chemical, especially in petrochemical production, with huge consumption and the resulting large quantities of waste acid containing high concentrations of sulfuric acid. Waste acid pyrolysis is an important environmental protection and resource recovery technology. Its core lies in pyrolyzing waste sulfuric acid at high temperatures to generate gaseous sulfur dioxide, water, and oxygen. Further, the catalytic oxidation of sulfur dioxide in the pyrolysis gas to sulfur trioxide, followed by purification and preheating, are crucial steps in the subsequent production of fresh concentrated sulfuric acid and fuming sulfuric acid.

[0003] The catalytic oxidation of sulfur dioxide to sulfur trioxide is extremely slow without a catalyst, and industrially, a highly efficient catalyst is necessary to achieve an economically feasible conversion rate. Generally, the catalysts used in this step are based on technology from large-scale sulfuric acid production plants, employing vanadium-based catalysts. These catalysts typically use vanadium pentoxide as the main active component, with alkali metal sulfates, including potassium sulfate, as co-catalysts, supported on porous carriers such as diatomaceous earth.

[0004] Although vanadium-based catalysts have mature applications and high inherent activity in sulfur dioxide catalysis, their long-term stability, resistance to poisoning, and adaptability to non-ideal operating conditions face severe challenges when directly applied to waste acid cracking. Catalyst deactivation significantly reduces sulfur dioxide conversion and increases energy consumption. Therefore, given the specific needs of sulfur dioxide catalytic oxidation in waste acid cracking processes—such as unstable catalyst supports, uneven active phase dispersion, and insufficient low-temperature activity—it is crucial to develop highly efficient sulfur dioxide oxidation catalysts with excellent resistance to poisoning, good thermal stability, and mechanical strength.

[0005] Patent CN111065458B discloses a vanadium-based catalyst and its preparation method, comprising: an active phase supported on a support, the active phase including vanadium oxide, potassium sulfate, sodium sulfate, and additives; the support including macroporous silica and diatomaceous earth, the macroporous silica having an average pore size of 100-500 nm, and the diatomaceous earth being refined diatomaceous earth with a silica content of over 85%. This vanadium-based catalyst exhibits high catalytic performance; however, when used in the conversion of sulfur dioxide to sulfur trioxide, the conversion rate of sulfur dioxide is only around 65%.

[0006] Therefore, there is an urgent need in the market for a vanadium-based catalyst that can improve the conversion rate of sulfur dioxide by cracking sulfur dioxide in waste acid to convert it into sulfur trioxide. Summary of the Invention

[0007] To address the problems existing in the prior art, the purpose of this invention is to obtain a vanadium-based catalyst for converting sulfur dioxide into sulfur trioxide by cracking waste acid, which has a high sulfur dioxide conversion rate and high strength.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] The first aspect of the present invention provides a vanadium-based catalyst for converting sulfur dioxide into sulfur trioxide by cracking waste acid, comprising an active phase supported on a composite support, wherein the active phase comprises a main active component and a co-active component; the composite support is macroporous oxide composite modified diatomite.

[0010] Preferably, the main active component is vanadium oxide; the auxiliary active component is selected from at least one of potassium sulfate, sodium sulfate, potassium sulfite, sodium sulfite, cesium sulfite, and phosphoric acid.

[0011] In the vanadium-based catalyst prepared in this application, the composite support, the co-active component, and the main active component form an optimized closed loop. The support provides a uniform and stable microenvironment for the active phase, the co-active component regulates the electronic structure of the active center and enhances low-temperature activity, and the liquid-phase reduction process achieves molecular-level dispersion and improves the utilization rate of active sites.

[0012] This application promotes the low-temperature adsorption and activation of sulfur dioxide by inducing a synergistic effect through the addition of co-activating components, thereby regulating the electronic environment of the vanadium active center of the catalyst.

[0013] The macroporous oxide composite modified diatomaceous earth support material used in this application overcomes the limitations of traditional diatomaceous earth supports. The macroporous oxide fills the pore size distribution of diatomaceous earth, forming narrow pore channels, which significantly improves the uniformity of active phase loading and avoids local reaction dead zones. The macroporous oxide, as a binder, combined with diatomaceous earth, significantly enhances the mechanical strength of vanadium-based catalysts, ensuring long-term operation of industrial plants.

[0014] The vanadium-based catalyst prepared in this application has strong cycle stability and is easy to recycle and reuse. It successfully solves the defects of traditional vanadium-based catalysts, such as uneven dispersion, poor low-temperature activity, and insufficient mechanical strength, and provides a reliable technical solution for the efficient conversion of sulfur dioxide from waste acid cracking.

[0015] In some embodiments, the preparation method of the macroporous oxide composite modified diatomite includes the following steps:

[0016] S1. N-ethylpiperazine and (3-iodopropyl)trimethoxysilane were added to acetonitrile, heated to 80-85℃, and refluxed under nitrogen for 12-24 h. The mixture was then dried to obtain the compound.

[0017] S2. Add the compound obtained in step S1 and iodomethane to acetonitrile, react at 25-40℃ for 6-10h under nitrogen protection, add diethyl ether to obtain a precipitate, wash and dry to obtain the modifier.

[0018] S3. Add the modifier obtained in step S2 and diatomaceous earth to an ethanol aqueous solution and react at 30-40℃ for 2-3 hours to obtain modified diatomaceous earth.

[0019] S4. Mix and stir the modified diatomite obtained in step S3 with macroporous oxide for 1-2 hours to obtain macroporous oxide composite modified diatomite.

[0020] Preferably, the mass ratio of the compound to iodomethane is 1:(0.95-1.43).

[0021] On the one hand, this application prepares a compound containing both a silane-oxy group and a piperazine group by reacting N-ethylpiperazine with (3-iodopropyl)trimethoxysilane. The silane-oxy group acts as an "anchor," subsequently undergoing a hydrolysis-condensation reaction with the silanol groups (-Si-OH) on the diatomaceous earth surface, thus firmly bonding to the diatomaceous earth surface. The piperazine group is a "functional precursor," containing a tertiary amine nitrogen atom, which can react with iodomethane to generate a quaternary ammonium salt, thereby introducing a quaternary ammonium salt group into the carrier material. This quaternary ammonium salt group is permanently positively charged in solution, while vanadium ions in aqueous solution usually exist as oxygen-containing anions, which can generate a strong electrostatic adsorption effect with the quaternary ammonium salt ions. This results in modified diatomaceous earth not only possessing a large specific surface area provided by its porous structure, but also having its surface loaded with quaternary ammonium salt sites capable of capturing vanadium ions, thereby increasing the adsorption capacity of vanadium ions on the modified diatomaceous earth. Furthermore, the two nitrogen atoms on the piperazine ring can work together to form a five- or six-membered chelate ring with stronger chemical adsorption, which greatly improves the adsorption selectivity, mechanical properties and stability of the composite support.

[0022] On the other hand, modified diatomite can generate strong interaction forces with negatively charged macroporous oxides, resulting in a composite support with a narrower pore size distribution. This reduces the impact of diatomite instability on catalyst performance and is beneficial for improving the loading effect of the active phase on the support.

[0023] In some embodiments, the macroporous oxide is selected from at least one of macroporous silica, macroporous alumina, macroporous zirconium oxide, macroporous cerium oxide, or macroporous lanthanum oxide.

[0024] Preferably, the macroporous oxide is macroporous SiO2.

[0025] In some embodiments, the method for preparing the macroporous SiO2 includes the following steps:

[0026] A1. Mix the silicon source with the solvent, add hydrochloric acid, adjust the pH to 1-3, and reflux for 2-4 hours under an inert gas atmosphere to obtain SiO2 sol.

[0027] A2. Immerse polystyrene microspheres in the SiO2 sol obtained in step A1 for 2-4 hours, filter, dry at 75-85℃ for 22-26 hours, perform programmed calcination in an inert gas atmosphere, and obtain macroporous SiO2 after cooling.

[0028] Preferably, the silicon source is selected from at least one of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, and isopropyl orthosilicate.

[0029] Preferably, the particle size of the polystyrene microspheres is 120-550 nm, more preferably 200-500 nm.

[0030] Preferably, the inert gas is nitrogen or argon.

[0031] In some embodiments, the mass ratio of N-ethylpiperazine to (3-iodopropyl)trimethoxysilane is (0.5-1):1.

[0032] In some embodiments, the mass ratio of the modifier to diatomaceous earth in step S3 is (0.1-0.2):1.

[0033] In some embodiments, the mass ratio of the modified diatomaceous earth to the macroporous oxide in step S4 is 1:(3-5).

[0034] In some embodiments, the diatomaceous earth is refined diatomaceous earth with a SiO2 content of 90-95%.

[0035] The second aspect of this invention provides a method for preparing a vanadium-based catalyst for converting sulfur dioxide into sulfur trioxide by cracking waste acid, comprising the following steps:

[0036] (1) Prepare a mixed solution of soluble vanadium source solution and potassium sulfite, and then neutralize the mixed solution with sulfuric acid to generate an active phase precursor;

[0037] (2) The active phase precursor obtained in step (1) is mixed with the composite support and the co-activating component, and then rolled, extruded, dried at 100-120℃ for 1-3 hours and calcined at 400-500℃ for 4-6 hours to obtain the vanadium-based catalyst.

[0038] Preferably, the soluble vanadium source solution is selected from at least one of potassium vanadate solution, sodium vanadate solution, ammonium metavanadate solution, or sodium ammonium vanadate solution.

[0039] Preferably, the method for preparing the soluble vanadium source solution includes the following steps: dissolving potassium hydroxide in water vapor and then adding vanadium pentoxide, and heating at 85-95℃ for 30-40 minutes to obtain a vanadium pentoxide content of 250g / L-270g / L.

[0040] Preferably, the potassium sulfite content in the mixed solution is 240-260 g / L.

[0041] In some embodiments, the vanadium-based catalyst contains 0.5-3 wt% of the co-active component and 5-15 wt% of the composite support.

[0042] The third aspect of this invention provides a vanadium-based catalyst for catalytic conversion of sulfur dioxide to sulfur trioxide in a waste acid cracking process, wherein the catalytic reaction conditions include: an inlet sulfur dioxide concentration of 8-12% and a space velocity of 3000-4000 h⁻¹. -1 .

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The vanadium-based catalyst prepared by the present invention has strong cycle stability and is easy to be recycled and reused. It successfully solves the defects of uneven dispersion, poor low-temperature activity and insufficient mechanical strength of traditional vanadium-based catalysts, and provides a reliable technical solution for the efficient conversion of sulfur dioxide from waste acid cracking.

[0045] (2) The modified diatomite prepared by this invention contains both quaternary ammonium salt groups and piperazine terminals, which not only provides a huge specific surface area due to the porous structure of the modified diatomite, but also loads quaternary ammonium salt sites on its surface that can capture vanadium ions, thereby increasing the adsorption capacity of vanadium ions on the modified diatomite. Furthermore, the two nitrogen atoms on the piperazine ring can work synergistically to form a five- or six-membered chelate ring with stronger chemical adsorption, which greatly improves the adsorption selectivity, mechanical properties and stability of the composite support.

[0046] (3) The present invention provides a method for preparing a catalyst for converting sulfur dioxide from waste acid cracking into sulfur trioxide. First, a soluble vanadium source solution is mixed with potassium sulfite to obtain a mixed solution. Then, the mixed solution is neutralized with sulfuric acid to generate an active phase precursor in an acidic environment. The pentavalent vanadium is reduced to tetravalent vanadium to generate a homogeneous solution without colloidal precipitation. The mixing of this solution with the composite support achieves molecular-level dispersion, solves the defects of traditional colloidal precipitation, improves the uniformity of active component dispersion from the source, and significantly improves catalytic activity. Detailed Implementation

[0047] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0048] In the following examples and comparative examples, except for the macroporous oxide composite modified diatomite, all other compounds and related reagents and raw materials used can be purchased from the market. Among them, the diatomite is diatomite with a SiO2 content of 93%, which was purchased from Lingshou County Zhengxi Mineral Products Sales Co., Ltd.; the average particle size of the polystyrene microspheres is 300nm.

[0049] Preparation Example 1

[0050] The preparation method of macroporous SiO2 includes the following steps:

[0051] A1. Tetraethyl orthosilicate, deionized water, and methanol were mixed in a molar ratio of 1:2:4. 37wt% hydrochloric acid was added to adjust the pH to 2. The mixture was refluxed for 3 hours under a nitrogen atmosphere to obtain SiO2 sol.

[0052] A2. The polystyrene microspheres were immersed in the SiO2 sol obtained in step A1 for 3 hours. The volume ratio of polystyrene microspheres to SiO2 sol was 1:5. The mixture was filtered, dried at 80°C, and then calcined in a nitrogen atmosphere. The temperature was first raised to 310°C and held for 5 hours, then raised to 550°C and held for 5 hours. After cooling, macroporous SiO2 was obtained.

[0053] Preparation Example 2

[0054] The preparation method of macroporous SiO2 composite modified diatomite-1 includes the following steps:

[0055] S1. 7.5g of N-ethylpiperazine and 10g of (3-iodopropyl)trimethoxysilane were added to 70g of acetonitrile, heated to 80℃, and refluxed under nitrogen for 14h. The mixture was then dried to obtain the compound.

[0056] S2. Add 10g of the compound obtained in step S1 and 12g of iodomethane to 70g of acetonitrile, react at 35°C for 8h under nitrogen protection, add 100g of anhydrous diethyl ether to obtain a precipitate, wash and dry to obtain the modifier.

[0057] S3. Add 1.5g of the modifier obtained in step S2 and 10g of diatomaceous earth to 70g of 80wt% ethanol aqueous solution, and react at 30-40℃ for 2-3h to obtain modified diatomaceous earth.

[0058] S4. Mix 10g of the modified diatomite obtained in step S3 with 40g of macroporous SiO2 and stir for 1.5h to obtain macroporous SiO2 composite modified diatomite-1.

[0059] Preparation Example 3

[0060] The preparation method of macroporous SiO2 composite modified diatomite-2 is the same as that in preparation example 1, except that the amount of N-ethylpiperazine added is 12g.

[0061] Preparation Example 4

[0062] The preparation method of macroporous SiO2 composite modified diatomite-3 is the same as that in preparation example 1, except that the amount of modifier added in step S3 is 2.5g.

[0063] Preparation Example 5

[0064] The preparation method of macroporous SiO2 composite modified diatomite-4 is the same as that in preparation example 1, except that the amount of macroporous SiO2 added is 55g.

[0065] Preparation Example 6

[0066] The preparation method of macroporous SiO2 composite diatomite includes the following steps: mixing 10g of diatomite and 40g of macroporous SiO2 and stirring for 1.5h to obtain macroporous SiO2 composite diatomite.

[0067] Example 1

[0068] A vanadium-based catalyst for converting sulfur dioxide to sulfur trioxide by cracking waste acid comprises an active phase supported on a composite support. The active phase includes a main active component and a co-active component. The main active component is vanadium oxide. The co-active component is sodium sulfate. The composite support is macroporous SiO2 composite modified diatomaceous earth-1.

[0069] The preparation method of the vanadium-based catalyst for converting sulfur dioxide to sulfur trioxide by waste acid cracking in this embodiment includes the following steps:

[0070] (1) Dissolve potassium hydroxide in water vapor and add vanadium pentoxide. Heat at 90°C for 35 minutes to obtain a soluble vanadium source solution with a K2O / V2O5 molar ratio of 3.5:1. Prepare a mixed solution of potassium sulfite from the soluble vanadium source solution. The potassium sulfite content in the mixed solution is 250 g / L. Then, neutralize the mixed solution with a sulfuric acid aqueous solution (using a sulfuric acid aqueous solution with a volume ratio of sulfuric acid to deionized water of 1:1). The volume ratio of the mixed solution to the sulfuric acid aqueous solution is 1:0.45 to generate an active phase precursor.

[0071] (2) The active phase precursor obtained in step (1) is mixed with macroporous SiO2 composite modified diatomite-1 and sodium sulfate, and then rolled and extruded into strips with a thickness of 6 mm. The strips are dried at 110 °C for 2 h and calcined at 450 °C for 5 h to obtain a vanadium-based catalyst. The content of macroporous SiO2 composite modified diatomite-1 in the vanadium-based catalyst is 10 wt%, and the content of sodium sulfate is 2 wt%.

[0072] Example 2

[0073] A vanadium-based catalyst for converting sulfur dioxide to sulfur trioxide by cracking waste acid comprises an active phase supported on a composite support. The active phase includes a main active component and a co-active component. The main active component is vanadium oxide. The co-active component is sodium sulfate. The composite support is macroporous SiO2 composite modified diatomaceous earth-1.

[0074] The preparation method of the vanadium-based catalyst for converting sulfur dioxide to sulfur trioxide by waste acid cracking in this embodiment includes the following steps:

[0075] (1) Dissolve potassium hydroxide in water vapor and add vanadium pentoxide. Heat at 85°C for 35 min to obtain a soluble vanadium source solution with a K2O / V2O5 molar ratio of 3.5:1. Prepare a mixed solution of potassium sulfite with a potassium sulfite content of 250 g / L. Then neutralize the mixed solution with an aqueous sulfuric acid solution (the volume ratio of sulfuric acid to deionized water is 1:1) with a volume ratio of 1:0.45 to generate an active phase precursor.

[0076] (2) The active phase precursor obtained in step (1) is mixed with macroporous SiO2 composite modified diatomite-1 and sodium sulfate, and then rolled and extruded into strips with a thickness of 6 mm. The strips are dried at 100°C for 3 h and calcined at 400°C for 6 h to obtain a vanadium-based catalyst. The content of macroporous SiO2 composite modified diatomite-1 in the vanadium-based catalyst is 5 wt%, and the content of sodium sulfate is 0.5 wt%.

[0077] Example 3

[0078] A vanadium-based catalyst for converting sulfur dioxide to sulfur trioxide by cracking waste acid comprises an active phase supported on a composite support. The active phase includes a main active component and a co-active component. The main active component is vanadium oxide. The co-active component is sodium sulfate. The composite support is macroporous SiO2 composite modified diatomaceous earth-1.

[0079] The preparation method of the vanadium-based catalyst for converting sulfur dioxide to sulfur trioxide by waste acid cracking in this embodiment includes the following steps:

[0080] (1) Dissolve potassium hydroxide in water vapor and add vanadium pentoxide. Heat at 95°C for 30 min to obtain a soluble vanadium source solution with a K2O / V2O5 molar ratio of 3.5:1. Prepare a mixed solution of potassium sulfite from the soluble vanadium source solution. The potassium sulfite content in the mixed solution is 250 g / L. Then, neutralize the mixed solution with a sulfuric acid aqueous solution (using a sulfuric acid aqueous solution with a volume ratio of sulfuric acid to deionized water of 1:1). The volume ratio of the mixed solution to the sulfuric acid aqueous solution is 1:0.45 to generate an active phase precursor.

[0081] (2) The active phase precursor obtained in step (1) is mixed with macroporous SiO2 composite modified diatomite-1 and sodium sulfate, and then rolled, extruded into strips with a thickness of 6 mm, dried and calcined to obtain a vanadium-based catalyst. The content of macroporous SiO2 composite modified diatomite-1 in the vanadium-based catalyst is 15 wt%, and the content of sodium sulfate is 3 wt%.

[0082] Example 4

[0083] A vanadium-based catalyst for converting sulfur dioxide into sulfur trioxide by cracking waste acid and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that macroporous SiO2 composite modified diatomite-1 is replaced by macroporous SiO2 composite modified diatomite-2 in equal amounts.

[0084] Example 5

[0085] A vanadium-based catalyst for converting sulfur dioxide into sulfur trioxide by cracking waste acid and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that macroporous SiO2 composite modified diatomite-1 is replaced by macroporous SiO2 composite modified diatomite-3 in an equal amount.

[0086] Example 6

[0087] A vanadium-based catalyst for converting sulfur dioxide into sulfur trioxide by cracking waste acid and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that macroporous SiO2 composite modified diatomite-1 is replaced by macroporous SiO2 composite modified diatomite-4 in an equal amount.

[0088] Comparative Example 1

[0089] A vanadium-based catalyst for converting sulfur dioxide into sulfur trioxide by cracking waste acid and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that macroporous SiO2 composite modified diatomite-1 is replaced with macroporous SiO2 composite diatomite in equal amounts.

[0090] Performance testing

[0091] The vanadium-based catalysts for converting sulfur dioxide to sulfur trioxide obtained from the above embodiments were tested:

[0092] (1) Sulfur dioxide conversion rate: Following the method specified in the Chinese chemical industry standard "HG / T 2089-2014 Experimental Method for Activity of Catalysts for Sulfur Dioxide Oxidation to Sulfuric Acid", the vanadium-based catalysts obtained in each example were loaded into the reactor. After confirming there were no leaks, 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 to be approximately 3500 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 for 5 hours. After reaching the heat resistance time, the temperature was decreased to the activation temperature of 410℃ 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. Finally, the SO2 conversion rate (E) was calculated using the following formula: where Vin is the SO2 inlet volume fraction and Vout is the SO2 outlet volume fraction.

[0093] E=(Vin-Vout) / (Vin×(1-0.015Vout))

[0094] (2) Radial compressive strength: The radial compressive strength of each vanadium-based catalyst was tested in accordance with ASTM D6175-03(2008).

[0095] The test results are shown in Table 1:

[0096] Table 1

[0097]

[0098] As shown in Table 1, the vanadium-based catalysts for converting sulfur dioxide to sulfur trioxide from waste acid cracking in Examples 1-3 of this application exhibit high sulfur dioxide conversion rates and radial compressive strength. A comparison between Example 4 and Example 1 shows that changing the ratio of N-ethylpiperazine to (3-iodopropyl)trimethoxysilane may result in N-ethylpiperazine remaining in the compound, leading to greater consumption of iodomethane and a decrease in the content of quaternary ammonium salt groups, thus reducing the sulfur dioxide conversion rate and radial compressive strength of the vanadium-based catalyst. A comparison between Examples 5, 6, and Example 1 shows that changing the ratio of the modifier to diatomaceous earth or modified diatomaceous earth and macroporous oxide may reduce the content of quaternary ammonium salt groups, thus reducing the sulfur dioxide conversion rate and radial compressive strength of the vanadium-based catalyst. A comparison between Comparative Example 1 and Example 1 shows that directly using macroporous SiO2 composite diatomaceous earth as the composite support results in a lower sulfur dioxide conversion rate and poorer radial compressive strength for the vanadium-based catalyst.

[0099] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A vanadium-based catalyst for the conversion of sulfur dioxide to sulfur trioxide by cracking of spent acid, comprising an active phase supported on a composite carrier, characterized in that, The active phase includes a main active component and a promoter active component; the main active component is vanadium oxide; the composite support is a macroporous oxide composite modified diatomaceous earth; The preparation method of the macroporous oxide composite modified diatomaceous earth comprises the following steps: S1. Add N-ethylpiperazine and (3-iodopropyl)trimethoxysilane into acetonitrile, heat up to 80 - 85 °C, reflux and react for 12 - 24 h under nitrogen, and dry to obtain a compound; S2. Add the compound obtained in step S1 and iodomethane into acetonitrile, react at 25 - 40 °C for 6 - 10 h under nitrogen protection, add into diethyl ether to obtain a precipitate, wash and dry to obtain a modifier; S3. Add the modifier obtained in step S2 and diatomaceous earth into an ethanol aqueous solution, react at 30 - 40 °C for 2 - 3 h to obtain modified diatomaceous earth; S4. Mix and stir the modified diatomaceous earth obtained in step S3 and the macroporous oxide for 1 - 2 h to obtain the macroporous oxide composite modified diatomaceous earth; The mass ratio of the N-ethylpiperazine to the (3-iodopropyl)trimethoxysilane is (0.5 - 1):1; In step S3, the mass ratio of the modifier to the diatomaceous earth is (0.1 - 0.2):1; In step S4, the mass ratio of the modified diatomaceous earth to the macroporous oxide is 1:(3 - 5); The macroporous oxide is selected from at least one of macroporous silica, macroporous alumina, macroporous zirconia, macroporous ceria or macroporous lanthanum oxide.

2. The vanadium-based catalyst for the conversion of sulfur trioxide from the cleavage of sulfur dioxide from spent acid according to claim 1, characterized in that, The diatomaceous earth is a diatomite concentrate with a SiO2 content of 90 - 95%.

3. A process for the preparation of a vanadium-based catalyst for the conversion of sulfur dioxide to sulfur trioxide by cleavage of waste acid according to any one of claims 1-2, characterized in that, It includes the following steps: (1) Prepare a mixed solution of a soluble vanadium source solution and potassium sulfite, and then carry out a neutralization reaction of the mixed solution with sulfuric acid to generate an active phase precursor; (2) Mix the active phase precursor obtained in step (1) with the composite support and the promoter active component, roll, extrude into pellets, dry at 100 - 120 °C for 1 - 3 h, and calcine at 400 - 500 °C for 4 - 6 h to obtain a vanadium-based catalyst.

4. The process for preparing a vanadium-based catalyst for the conversion of sulfur trioxide from the cracking of sulfur dioxide in spent acid according to claim 3, characterized in that, The content of the promoter active component in the vanadium-based catalyst is 0.5 - 3 wt%, and the content of the composite support is 5 - 15 wt%.

5. Use of a vanadium-based catalyst for the conversion of sulfur dioxide to sulfur trioxide by spent acid cracking according to any one of claims 1 to 2 or a vanadium-based catalyst for the conversion of sulfur dioxide to sulfur trioxide by spent acid cracking obtained by the production process according to any one of claims 3 to 4, characterized in that, The application relates to a method for catalytically converting sulfur dioxide into sulfur trioxide in a waste acid cracking process, and the catalytic reaction conditions comprise the following: the concentration of the sulfur dioxide gas inlet is 8-12%; the space velocity is 3000-4000h -1 .

Images