Iron oxyhydroxide desulfurization catalyst prepared from titanium dioxide by-product copperas and preparation method thereof

Abstract

The invention relates to an iron oxyhydroxide desulfurization catalyst prepared by utilizing a titanium dioxide byproduct copperas and a preparation method thereof, and belongs to the technical field of catalysts, the preparation method of the iron oxyhydroxide desulfurization catalyst prepared by utilizing the titanium dioxide byproduct copperas comprises two steps of preparing iron oxyhydroxide and preparing the iron oxyhydroxide desulfurization catalyst; the breakthrough sulfur capacity of the iron oxyhydroxide desulfurization catalyst prepared from the titanium dioxide by-product copperas is 40.1-43.4%.

Description

Technical Field

[0001] The present invention relates to a hydroxyl iron oxide desulfurization catalyst prepared from by - product green vitriol of titanium dioxide and a preparation method thereof, belonging to the technical field of catalysts. Background Art

[0002] Sulfides are generated in many occasions in industrial production. For example, in the production process of using coal or petroleum to produce chemical raw materials, as well as in the waste water or waste gas discharged from ordinary industrial production, there are a lot of sulfur - containing substances, and they mainly exist in the form of hydrogen sulfide. Hydrogen sulfide is highly toxic, which not only affects human health, but also causes serious problems in industrial application scenarios such as pipelines, equipment, and catalysts. Therefore, industrial desulfurizers, especially high - performance desulfurizers dedicated to hydrogen sulfide removal, have always been a hot product in key research and development in the industrial field.

[0003] Hydroxyl iron oxide desulfurization is a traditional gas purification method with relatively mature technology. Its resources are rich and the price is low. It has a very high theoretical breakthrough sulfur capacity (54.12%) at room temperature. Therefore, hydroxyl iron oxide has been widely used in the field of room - temperature desulfurization. The raw materials for preparing hydroxyl iron oxide are mainly ferrous salts, such as ferrous chloride, ferrous nitrate, ferrous sulfate, etc. Among them, the hydroxyl iron oxide prepared from ferrous sulfate heptahydrate has relatively high desulfurization performance. According to the disclosed laboratory data, the breakthrough sulfur capacity of the hydroxyl iron oxide synthesized from ferrous sulfate heptahydrate can reach 51.38%. The dosage of desulfurizer is very large. At present, in order to obtain ferrous sulfate heptahydrate with lower cost, the industrial circle has focused on the research and development of by - product green vitriol of titanium dioxide. Because for every 1 ton of titanium dioxide produced, 3 - 4 tons of by - product green vitriol are generated, and the content of ferrous sulfate heptahydrate in green vitriol is more than 80%. More advantageously, the by - product of titanium dioxide contains TiO 2+ , Mn 2+ , Mg 2+ , Al 3+ and other impurities, which have no adverse effect on the desulfurization reaction. Also, because the production capacity of titanium dioxide is in the million - ton level, using by - product green vitriol of titanium dioxide to prepare hydroxyl iron oxide has the significant advantages of rich raw materials, low price, and no need for purification treatment.

[0004] Although the preparation of iron oxyhydroxide using the by-product green vitriol of titanium dioxide can turn waste into treasure and achieve the resource utilization of solid waste, the desulfurization performance of the iron oxyhydroxide prepared from the by-product green vitriol of titanium dioxide is not ideal at present. For example, Chinese Patent CN114768837A discloses an iron oxyhydroxide desulfurization catalyst prepared from the by-product green vitriol of titanium dioxide and its preparation method. The catalyst is composed of the following components by mass percentage: 25-35% of iron oxyhydroxide, 55-65% of calcium sulfate dihydrate, and 4-20% of others; the preparation method is: mixing and grinding the by-product green vitriol of titanium dioxide with industrial calcium hydroxide, extruding, and then naturally drying. The iron oxyhydroxide desulfurization catalyst prepared by this invention takes the iron oxyhydroxide synthesized from the by-product green vitriol of titanium dioxide as the main component, and calcium sulfate dihydrate and others as the remaining components, realizing the full utilization of the by-product green vitriol of titanium dioxide and reducing the raw material cost. However, the highest breakthrough sulfur capacity of the iron oxyhydroxide desulfurization catalyst obtained by this patent is only 16.2%, far lower than the theoretical breakthrough sulfur capacity of iron oxyhydroxide and the actual breakthrough sulfur capacity that can be achieved in the laboratory.

[0005] It can be seen that the iron oxyhydroxide desulfurization catalyst prepared from the by-product green vitriol of titanium dioxide has extremely high industrial application value, but the prominent problem of low breakthrough sulfur capacity still needs to be solved to be more suitable for large-scale low-cost applications in the industrial field. Summary of the Invention

[0006] Aiming at the deficiencies of the above-mentioned existing technologies, the present invention provides an iron oxyhydroxide desulfurization catalyst prepared from the by-product green vitriol of titanium dioxide and its preparation method, achieving the following invention objectives: preparing an iron oxyhydroxide desulfurization catalyst with a very high breakthrough sulfur capacity at room temperature by using the by-product green vitriol of titanium dioxide.

[0007] To achieve the above invention objectives, the present invention adopts the following technical solutions: An iron oxyhydroxide desulfurization catalyst prepared from the by-product green vitriol of titanium dioxide and its preparation method, the breakthrough sulfur capacity of the iron oxyhydroxide desulfurization catalyst prepared from the by-product green vitriol of titanium dioxide is 40.1-43.4%; The preparation method of the iron oxyhydroxide desulfurization catalyst prepared from the by-product green vitriol of titanium dioxide includes two steps: preparing iron oxyhydroxide and preparing the iron oxyhydroxide desulfurization catalyst. The following is a further improvement of the above technical solution:

[0008] Step 1, Prepare iron oxyhydroxide Put by-product green vitriol of titanium dioxide and deionized water into a reaction kettle. Under the protection of nitrogen, stir and dissolve. After complete dissolution, add a composite precipitant dropwise, and control the pH of the solution in the kettle to be 6 - 7.8. After the addition of the composite precipitant is completed, then add a peroxide. At the same time, switch nitrogen to air, continuously introduce air and stir to carry out an oxidation reaction. When the color of the solution in the kettle no longer changes, stop introducing air and stirring, discharge and filter by suction. After the filter cake is washed and dried, iron oxyhydroxide is obtained; The composite precipitant is obtained by mixing and dissolving a diamine substance, a quaternary ammonium base, and deionized water; The diamine substance is a mixture composed of one or both of 2-hydroxyethylamine and ethylenediamine in any mass ratio; The quaternary ammonium base is one or a mixture composed of any two in any mass ratio or any two or more in any mass ratio among tetramethylammonium hydroxide, tetraethylammonium hydroxide, hexamethylenediamine hydroxide, tetrabutylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylphosphonium hydroxide; The peroxide is one or a mixture composed of any two in any mass ratio or any two or more in any mass ratio among calcium peroxide, magnesium peroxide, potassium peroxide, sodium peroxide, and zinc peroxide; The mass ratio of the diamine substance, the quaternary ammonium base, and deionized water is 7 - 19:5 - 30:90 - 250; The mass ratio of the by-product green vitriol of titanium dioxide, deionized water, the composite precipitant, and the peroxide is 50 - 120:160 - 390:25 - 80:1 - 6; During the continuous introduction of air and stirring, the air flow rate is 40 - 100 L / h, and the stirring rate is 500 - 900 revolutions per minute; For the washing, wash with deionized water until the pH value of the washing liquid is neutral; For the drying, dry at 80 - 100 °C for 7 - 13 hours.

[0009] Step 2: Prepare an iron oxyhydroxide desulfurization catalyst Put iron oxyhydroxide, an activity promoter, calcium-based bentonite, sodium carboxymethylcellulose, and deionized water into a double planetary mixer. After stirring and dispersing into a paste, transfer it to an extruder to extrude long strip-shaped particles, and then obtain a strip-shaped iron oxyhydroxide desulfurization catalyst after drying; The activity promoter is a mixture composed of one or both of copper bismuthate and sodium bismuthate in any mass ratio; The mass ratio of iron oxyhydroxide, the activity promoter, calcium-based bentonite, sodium carboxymethylcellulose, and deionized water is 40 - 90:5 - 13:90 - 240:4 - 10:25 - 50; For the stirring and dispersion, the stirring rate is 100 - 150 revolutions per minute, and the dispersion rate is 5000 - 9000 revolutions per minute; For the long strip particles, the cross-sectional diameter is 2 - 6 mm, and the length is 8 - 20 mm; For the drying, the drying temperature is 50 - 65 °C, and the drying time is 25 - 44 hours.

[0010] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses a quaternary ammonium base and a diamine substance to form a composite precipitant. The composite precipitant formed by combining these two substances can not only accurately control the pH fluctuation range of the reaction system, providing a stable pH fluctuation range for the uniform precipitation of iron ions, but also form a certain degree of complexation and adsorption effect with iron ions, accelerating the precipitation rate of iron ions, making its particle size smaller and more uniform. This will also promote the development of its particle size towards the nanoscale, ultimately promoting a significant increase in the specific surface area of iron oxyhydroxide; 2. The present invention uses peroxide and air, two oxidizing substances, to rapidly and fully oxidize the iron ion precipitate. The oxygen free radicals generated by the decomposition of peroxide in water will greatly enhance the oxidizing property brought by the oxygen in the air. The oxygen free radicals generated by peroxide cooperate with the oxygen in the air, and the superimposed strong oxidation effect of the two will promote the efficiency and uniformity of the oxidation reaction in the system, and then finer iron oxyhydroxide with a particle size reaching the nanoscale will be obtained, ultimately ensuring the specific surface area and high catalytic activity of iron oxyhydroxide, that is, maximizing the breakthrough sulfur capacity of the catalyst; 3. The copper bismuthate and sodium bismuthate added in the present invention, as the activity promoters of the iron oxyhydroxide desulfurization catalyst, may form a composite oxide with iron oxyhydroxide. This composite oxide has a certain promoting effect on the ability of iron oxyhydroxide to bind sulfur elements, thereby improving the desulfurization reaction activity and ultimately increasing the breakthrough sulfur capacity of the iron oxyhydroxide desulfurizer; 4. The iron oxyhydroxide desulfurization catalyst prepared from the by-product ferrous sulfate heptahydrate of titanium dioxide obtained in the present invention has a breakthrough sulfur capacity of 40.1 - 43.4%. Description of the Drawings

[0011] Figure 1 It is a scanning electron microscope photograph of the iron oxyhydroxide obtained in step 1 of Example 1 with its surface magnified 10,000 times; Figure 2 It is a scanning electron microscope photograph of the iron oxyhydroxide obtained in step 1 of Example 1 with its surface magnified 50,000 times. Detailed Embodiments

[0012] The preferred embodiments of the present invention will be described below. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0013] Example 1: A preparation method of a hydroxyl iron oxide desulfurization catalyst prepared from by - product green vitriol of titanium dioxide Step 1: Preparation of hydroxyl iron oxide Put the by - product green vitriol of titanium dioxide and deionized water into a reaction kettle. Under nitrogen protection, stir and dissolve. After complete dissolution, add a composite precipitant dropwise, and control the pH of the solution in the kettle at 6.8. After the composite precipitant is added dropwise, then add a peroxide. At the same time, switch nitrogen to air, continuously introduce air and stir to carry out an oxidation reaction. When the color of the solution in the kettle no longer changes, stop introducing air and stirring, discharge and filter. The filtered product is then washed and dried to obtain hydroxyl iron oxide; The composite precipitant is obtained by mixing and dissolving a diamine substance, a quaternary ammonium base, and deionized water; The diamine substance is 2 - hydroxyethylamine; The quaternary ammonium base is tetramethylammonium hydroxide; The peroxide is calcium peroxide; The mass ratio of the diamine substance, the quaternary ammonium base, and deionized water is 11:20:180; The mass ratio of the by - product green vitriol of titanium dioxide, deionized water, the composite precipitant, and the peroxide is 90:300:60:5; When continuously introducing air and stirring, the air flow rate is 55 L / h, and the stirring rate is 800 revolutions per minute; For the washing, wash with deionized water until the pH value of the washing liquid is neutral; For the drying, dry at 90 °C for 11 hours.

[0014] Step 2: Preparation of hydroxyl iron oxide desulfurization catalyst Put hydroxyl iron oxide, an activity promoter, calcium - based bentonite, sodium carboxymethyl cellulose, and deionized water into a double - planetary mixer. After stirring and dispersing into a paste, transfer it to an extruder to extrude long - strip particles, and then dry to obtain strip - shaped hydroxyl iron oxide desulfurization catalyst; The activity promoter is copper bismuthate; The mass ratio of hydroxyl iron oxide, the activity promoter, calcium - based bentonite, sodium carboxymethyl cellulose, and deionized water is 70:11:150:7:40; For the stirring and dispersing, the stirring rate is 120 revolutions per minute, and the dispersion rate is 8000 revolutions per minute; For the long - strip particles, the cross - sectional diameter is 5 mm and the length is 18 mm; For the drying, the drying temperature is 60°C and the drying time is 35 hours.

[0015] Example 2: A preparation method of a hydroxyl iron oxide desulfurization catalyst prepared from by - product green vitriol of titanium dioxide Step 1: Preparation of hydroxyl iron oxide Put the by - product green vitriol of titanium dioxide and deionized water into a reaction kettle. Under nitrogen protection, stir and dissolve. After complete dissolution, add a composite precipitant dropwise, and control the pH of the solution in the kettle at 6. After the addition of the composite precipitant is completed, then add a peroxide, and at the same time switch nitrogen to air, continuously introduce air and stir to carry out an oxidation reaction. When the color of the solution in the kettle no longer changes, stop introducing air and stirring, discharge and filter. The filtered product is washed and dried to obtain hydroxyl iron oxide; The composite precipitant is obtained by mixing and dissolving a diamine substance, a quaternary ammonium base, and deionized water; The diamine substance is ethylenediamine; The quaternary ammonium base is tetraethylammonium hydroxide; The peroxide is magnesium peroxide; The mass ratio of the diamine substance, the quaternary ammonium base, and deionized water is 7:5:90; The mass ratio of the by - product green vitriol of titanium dioxide, deionized water, the composite precipitant, and the peroxide is 50:160:25:1; For the continuous introduction of air and stirring, the air flow rate is 40 L / h and the stirring rate is 500 revolutions per minute; For the washing, wash with deionized water until the pH value of the washing liquid is neutral; For the drying, dry at 80°C for 7 hours.

[0016] Step 2: Preparation of hydroxyl iron oxide desulfurization catalyst Put hydroxyl iron oxide, an activity promoter, calcium - based bentonite, sodium carboxymethylcellulose, and deionized water into a double - planetary mixer. After stirring and dispersing into a paste, transfer it to an extruder to extrude long - strip particles, and then dry to obtain strip - shaped hydroxyl iron oxide desulfurization catalyst; The activity promoter is sodium bismuthate; The mass ratio of hydroxyl iron oxide, the activity promoter, calcium - based bentonite, sodium carboxymethylcellulose, and deionized water is 40:5:90:4:25; For the stirring and dispersing, the stirring rate is 100 revolutions per minute and the dispersion rate is 5000 revolutions per minute; For the long - strip particles, the cross - sectional diameter is 2 mm and the length is 8 mm; For the drying, the drying temperature is 50°C and the drying time is 25 hours.

[0017] Example 3: Preparation Method of Hydroxy Iron Oxide Desulfurization Catalyst Prepared from By-Product Ferrous Sulfate of Titanium Dioxide Step 1: Preparation of hydroxy iron oxide Put the by-product ferrous sulfate of titanium dioxide and deionized water into a reaction kettle. Under nitrogen protection, stir and dissolve. After complete dissolution, add a composite precipitant dropwise, and control the pH of the solution in the kettle at 7.8. After the addition of the composite precipitant is completed, add a peroxide, and at the same time switch the nitrogen to air, continuously introduce air and stir to carry out an oxidation reaction. When the color of the solution in the kettle no longer changes, stop the introduction of air and stirring, discharge and filter. The filtrate is washed and dried to obtain hydroxy iron oxide; The composite precipitant is obtained by mixing and dissolving a diamine substance, a quaternary ammonium base, and deionized water; The diamine substance is 2-hydroxyethylamine; The quaternary ammonium base is hexamethylenediammonium hydroxide; The peroxide is potassium peroxide; The mass ratio of the diamine substance, the quaternary ammonium base, and deionized water is 19:30:250; The mass ratio of the by-product ferrous sulfate of titanium dioxide, deionized water, the composite precipitant, and the peroxide is 120:390:80:6; During the continuous introduction of air and stirring, the air flow rate is 100 L / h, and the stirring rate is 900 revolutions per minute; For the washing, wash with deionized water until the pH value of the washing liquid is neutral; For the drying, dry at 100 °C for 13 hours.

[0018] Step 2: Preparation of hydroxy iron oxide desulfurization catalyst Put hydroxy iron oxide, an activity promoter, calcium-based bentonite, sodium carboxymethylcellulose, and deionized water into a double planetary mixer. After stirring and dispersing into a paste, transfer it to an extruder to extrude long strip-shaped particles, and then dry to obtain strip-shaped hydroxy iron oxide desulfurization catalyst; The activity promoter is copper bismuthate; The mass ratio of hydroxy iron oxide, the activity promoter, calcium-based bentonite, sodium carboxymethylcellulose, and deionized water is 90:13:240:10:50; For the stirring and dispersing, the stirring rate is 150 revolutions per minute, and the dispersing rate is 9000 revolutions per minute; For the long strip-shaped particles, the cross-sectional diameter is 6 mm and the length is 20 mm; For the drying, the drying temperature is 65 °C and the drying time is 44 hours.

[0019] Example 4: Preparation Method of Hydroxy Iron Oxide Desulfurization Catalyst Prepared from By-Product Ferrous Sulfate of Titanium Dioxide Step 1: Prepare iron oxyhydroxide The quaternary ammonium base is tetrabutylammonium hydroxide; The peroxide is sodium peroxide; Other operations are the same as those in Example 1; The operation of Step 2 is the same as that in Example 1.

[0020] Example 5: A preparation method of an iron oxyhydroxide desulfurization catalyst prepared from by - product ferrous sulfate of titanium dioxide Step 1: Prepare iron oxyhydroxide The quaternary ammonium base is tetrapropylammonium hydroxide; The peroxide is zinc peroxide; Other operations are the same as those in Example 1; The operation of Step 2 is the same as that in Example 1.

[0021] Example 6: A preparation method of an iron oxyhydroxide desulfurization catalyst prepared from by - product ferrous sulfate of titanium dioxide Step 1: Prepare iron oxyhydroxide The quaternary ammonium base is tetrabutylphosphonium hydroxide; Other operations are the same as those in Example 1; The operation of Step 2 is the same as that in Example 1. Comparative Example 1: Based on Example 1, in Step 1 of preparing iron oxyhydroxide, replace the composite precipitant with ammonia water. The specific operation is as follows:

[0022] Step 1: Prepare iron oxyhydroxide Replace the composite precipitant with ammonia water, and other operations are the same as those in Example 1; The operation of Step 2 is the same as that in Example 1. Comparative Example 2: Based on Example 1, in Step 1 of preparing iron oxyhydroxide, do not add peroxide. The specific operation is as follows:

[0023] Step 1: Prepare iron oxyhydroxide Do not add peroxide, and other operations are the same as those in Example 1; The operation of Step 2 is the same as that in Example 1. Comparative Example 3: Based on Example 1, in Step 2 of preparing the iron oxyhydroxide desulfurization catalyst, replace 11 parts of the activity promoter with 11 parts of iron oxyhydroxide. The specific operation is as follows:

[0024] The operation of Step 1 is the same as that in Example 1; Step 2: Prepare the iron oxyhydroxide desulfurization catalyst Replace 11 parts of the activity promoter with 11 parts of iron oxyhydroxide, and other operations are the same as those in Example 1.

[0025] Performance test: The hydroxyl iron oxide desulfurization catalysts prepared from by - product melanterite of titanium dioxide in Examples 1, 2, 3, 4, 5, 6 and Comparative Examples 1, 2, 3 were loaded into a fixed - bed reactor of a hard quartz tube with a diameter of φ10mm×200mm (diameter×length). Quartz sand was filled at both the upper and lower ends of the catalyst. Under normal temperature, normal pressure and a gas hourly space velocity of 1000h -1 conditions, the desulfurization activity test of the catalyst was carried out to investigate the breakthrough sulfur capacity of the hydroxyl iron oxide desulfurization catalyst. The H2S content at the outlet of the desulfurization reactor was analyzed by an Agilent GC 7890A chromatograph and a H2S rapid detection tube. The condition for testing the breakthrough sulfur capacity was that the volume fraction of H2S in the inlet feed gas was 1.0%. When the volume fraction of H2S at the outlet exceeded 0.5 ppm, it was considered to have broken through, and the desulfurization performance test was stopped. The breakthrough sulfur capacity was calculated according to the following formula: W = V×C 硫化氢 ×32.06÷[22.41×(100 - C 硫化氢 )×m]×100 In the above formula: C 硫化氢 — the numerical value of the volume fraction of hydrogen sulfide gas in the hydrogen sulfide standard gas, unit %; V — the numerical value of the volume of the hydrogen sulfide standard gas passing through, unit L; 32.06 — the molar mass of sulfur element, unit g / mol; m — the mass of the hydroxyl iron oxide desulfurization catalyst sample, unit g; 22.41 — the numerical value of the molar volume of an ideal gas under standard conditions, unit L / mol; The test results are shown in Table 1: Table 1

[0026] As can be seen from the test data in Table 1, the breakthrough sulfur capacity of Examples 1-6 is all above 40%, which indicates that the iron oxyhydroxide desulfurization catalyst prepared from the by-product green vitriol of titanium dioxide in the present invention has a very high breakthrough sulfur capacity; in Comparative Example 1, the composite precipitant was replaced with ammonia water, and the breakthrough sulfur capacity of Comparative Example 1 decreased to 24.7%, which indicates that the composite precipitant can provide a more stable pH fluctuation range compared with ammonia water, which is more conducive to the rapid formation of iron ions into precipitates, making the particle size of the precipitates smaller, which is beneficial to obtaining iron oxyhydroxide with a larger specific surface area and better catalytic performance during the subsequent oxidation process; in Comparative Example 2, no peroxide was added, and the breakthrough sulfur capacity of Comparative Example 2 decreased to 22.4%, which indicates that the peroxide can effectively promote the oxidation of alkaline precipitates and promote the rapid formation of iron oxyhydroxide, thereby obtaining iron oxyhydroxide with a larger specific surface area and higher catalytic activity; in Comparative Example 3, no activity promoter was added, and the breakthrough sulfur capacity of Comparative Example 3 decreased to 26.9%, which indicates that the activity promoter can greatly improve the catalytic activity of iron oxyhydroxide. The activity promoter, namely copper bismuthate or sodium bismuthate, may form a composite oxide with iron oxyhydroxide during the drying process. This composite oxide has a certain promoting effect on the ability of iron oxyhydroxide to bind sulfur elements, thereby improving the desulfurization reaction activity and ultimately increasing the breakthrough sulfur capacity of the iron oxyhydroxide desulfurizer.

[0027] Attached Figure 1 and attached Figure 2 are the scanning electron microscope photos of the iron oxyhydroxide obtained in Step 1 of Example 1, with the surface magnified 10,000 times and 50,000 times respectively. Attached Figure 1 and attached Figure 2 it can be seen that the iron oxyhydroxide is in the shape of strip-like thin flakes, with a thickness in the nanoscale and a length basically in the micron level. This indicates that the iron oxyhydroxide obtained in the present invention has the size of a nanomaterial in a certain dimension, so its specific surface area is very large, and thus it exhibits very excellent desulfurization performance.

[0028] The above is only the preferred specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A preparation method of a hydroxyl iron oxide desulfurization catalyst prepared by using by - product green vitriol of titanium dioxide, characterized in that: The preparation method of the hydroxyl iron oxide desulfurization catalyst prepared by using by - product green vitriol of titanium dioxide includes two steps: preparing hydroxyl iron oxide and preparing the hydroxyl iron oxide desulfurization catalyst; For the preparation of hydroxyl iron oxide, put by - product green vitriol of titanium dioxide and deionized water into a reaction kettle. Under nitrogen protection, stir and dissolve. After complete dissolution, dropwise add a composite precipitant, control the pH of the solution in the kettle at 6 - 7.

8. After the composite precipitant is added dropwise, then add a peroxide. At the same time, switch nitrogen to air, continuously introduce air and stir to carry out an oxidation reaction. When the color of the solution in the kettle no longer changes, stop introducing air and stirring, discharge and filter. The filtered product is then washed and dried to obtain hydroxyl iron oxide; The composite precipitant is obtained by mixing and dissolving a diamine substance, a quaternary ammonium base and deionized water; For the preparation of the hydroxyl iron oxide desulfurization catalyst, put hydroxyl iron oxide, an activity promoter, calcium - based bentonite, sodium carboxymethyl cellulose and deionized water into a double - planetary mixer, stir and disperse into a paste, then transfer it to an extruder to extrude long - strip particles, and then dry to obtain a strip - shaped hydroxyl iron oxide desulfurization catalyst; The activity promoter is a mixture composed of one or both of copper bismuthate and sodium bismuthate in any mass ratio.

2. The preparation method of the hydroxyl iron oxide desulfurization catalyst prepared by using by - product green vitriol of titanium dioxide according to claim 1, characterized in that: The diamine substance is a mixture composed of one or both of 2 - hydroxyethylamine and ethylenediamine in any mass ratio; The quaternary ammonium base is one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, hexamethylenediamine hydroxide, tetrabutylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylphosphonium hydroxide or a mixture composed of any two in any mass ratio or any two or more in any mass ratio; The peroxide is one of calcium peroxide, magnesium peroxide, potassium peroxide, sodium peroxide, zinc peroxide or a mixture composed of any two in any mass ratio or any two or more in any mass ratio.

3. The preparation method of the hydroxyl iron oxide desulfurization catalyst prepared by using by - product green vitriol of titanium dioxide according to claim 1, characterized in that: The mass ratio of the diamine substance, the quaternary ammonium base and deionized water is 7 - 19:5 - 30:90 - 250; The mass ratio of the by - product green vitriol of titanium dioxide, deionized water, the composite precipitant and the peroxide is 50 - 120:160 - 390:25 - 80:1 - 6.

4. The preparation method of the hydroxyl iron oxide desulfurization catalyst prepared by using by - product green vitriol of titanium dioxide according to claim 1, characterized in that: The mass ratio of the hydroxyl iron oxide, the activity promoter, calcium - based bentonite, sodium carboxymethyl cellulose and deionized water is 40 - 90:5 - 13:90 - 240:4 - 10:25 - 50.

5. The preparation method of the hydroxyl iron oxide desulfurization catalyst prepared by using by - product green vitriol of titanium dioxide according to claim 1, characterized in that: For the stirring and dispersion, the stirring rate is 100 - 150 revolutions per minute, and the dispersion rate is 5000 - 9000 revolutions per minute; For the long strip-shaped particles, the cross-sectional diameter is 2 - 6 mm, and the length is 8 - 20 mm; For the drying, the drying temperature is 50 - 65 °C, and the drying time is 25 - 44 hours.

6. The hydroxyl iron oxide desulfurization catalyst prepared from the by-product green vitriol of titanium dioxide using the preparation method according to any one of claims 1 - 5, wherein: For the hydroxyl iron oxide desulfurization catalyst prepared from the by-product green vitriol of titanium dioxide, the breakthrough sulfur capacity is 40.1 - 43.4%.

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