A desulfurizing agent for improving purification degree of decarburization vent gas and a preparation method thereof
By preparing acid-modified halloysite-supported ZnS and MnO open-cell foamed ceramics and combining them with iron oxide, the problem of poor H2S treatment effect in decarbonization venting was solved, realizing the application of a high-efficiency and long-life desulfurizer.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIANGYANG ZEDONG CHEM GRP CO LTD
- Filing Date
- 2023-05-31
- Publication Date
- 2026-07-31
AI Technical Summary
Existing decarbonization methods have poor H2S treatment effects in the released air. Activated carbon has low sulfur capacity and a short service life, failing to meet environmental standards. Iron oxide desulfurizers have low precision and are difficult to regenerate, impacting the environment and safety.
Open-cell foamed ceramics were prepared by loading ZnS and MnO with acid-modified halloysite, and mixing with calcite, diatomite, and silicon carbide. Iron oxide was loaded to form a porous structure, which promoted the H2S reaction and allowed for wet regeneration.
It improves desulfurization precision and intensity, extends service life, enhances H2S removal efficiency, avoids pore blockage, and achieves efficient H2S purification and good regenerability in desulfurization.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of desulfurizing agent technology, and specifically relates to a desulfurizing agent that improves the air purification efficiency after decarbonization and its preparation method. Background Technology
[0002] In the ammonia production process, the shift gas undergoes desulfurization, with the H2S content controlled below 15 mg / m3. This shift gas is then sent to the decarbonization station, where CO2 and H2S are removed simultaneously. The exhaust air from the decarbonization process contains trace amounts of H2S, which is currently typically absorbed by activated carbon. However, activated carbon has a sulfur capacity of only 5%, a short service life (usually around one year), and poor treatment efficiency, failing to meet the "Odor Pollutant Emission Standard." Because H2S is heavier than air, it does not easily diffuse and settle under low atmospheric pressure and calm weather conditions, resulting in a noticeable H2S odor around the decarbonization site, severely impacting the surrounding environment.
[0003] Iron oxide desulfurizer is a common dry desulfurizer. H2S molecules diffuse to the surface of hydrated iron oxide, dissolve in the water film on its surface, and dissociate into H2S. - and S 2- Ions, subsequently, the generated HS - and S 2- Ions and lattice oxygen (OH) in water and iron oxide - It reacts with O2, replacing it with iron sulfide and ferrous sulfide. Furthermore, the iron oxide desulfurizer can be regenerated through the reaction of oxygen and water. During the reaction, sulfide ions are replaced by oxide ions, generating elemental S, which can be recycled. Iron oxide desulfurizers have advantages such as good desulfurization reactivity, low price, and the ability to be regenerated with air at low temperatures, making them a widely used desulfurizer. However, they also have a series of problems, including low desulfurization precision, poor strength, poor safety of the FeS product, and the generation of a large amount of reaction heat during the desulfurization process, leading to uncontrolled bed temperature. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing a desulfurizing agent that improves the air purification efficiency after decarbonization, which has the effects of high desulfurization accuracy, high strength, mild reaction, and long service life.
[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a method for preparing a desulfurizing agent that improves the air purification efficiency after decarbonization, characterized by comprising the following steps: S1. Acid-modified halloysite is loaded with ZnS by vacuum negative pressure method to obtain ZnS-modified halloysite; S2. Mix ZnS-modified halloysite, MnO, calcite, diatomite and silicon carbide and place them in a ball mill. Add water to the ball mill and wet mill for 30-60 minutes. Dry, granulate and sinter the wet-milled and uniformly mixed slurry. After sintering, open-cell foamed ceramic particles are obtained. S3. Iron oxide is loaded onto the open-cell foamed ceramic particles using a co-precipitation method to obtain an iron oxide-loaded open-cell foamed ceramic desulfurizer.
[0006] A further provision of the present invention is that step S1 includes: preparing a 2-3 mol / L hydrochloric acid solution, mixing halloysite with the hydrochloric acid solution, stirring evenly at 60-80°C, ultrasonically treating for 30-60 minutes, filtering, drying, and grinding into powder after the reaction is completed to obtain acid-modified halloysite powder.
[0007] A further setting of the present invention is as follows: the acid-modified halloysite powder is mixed with ZnS solution, and then the mixture is placed in a vacuum dryer and kept under vacuum for 30-60 minutes. The vacuum dryer valve is opened to release the air. The vacuuming and venting process is repeated 3-5 times. After the load is completed, the mixture is centrifuged, precipitated, washed with dilute hydrochloric acid, dried and ground into powder to obtain ZnS-modified halloysite.
[0008] A further provision of the present invention is that step S2 includes 60-70 parts of modified halloysite, 10-15 parts of calcite, 15-20 parts of diatomite, and 0.3-0.5 parts of silicon carbide.
[0009] A further provision of the present invention is that step S2 further includes 2 to 5 parts of MnO.
[0010] A further provision of the present invention is that step S3 includes: preparing an aqueous solution of FeCl3·6H2O, adding open-cell foamed ceramic particles to the solution and stirring thoroughly, ultrasonically treating the mixed solution for 30-60 minutes, then adding KOH solution to the solution while stirring, aging the mixture of open-cell foamed ceramic and precipitate suspension at a constant temperature of 60°C for 2-3 hours, and then filtering, washing, drying, and sintering to obtain open-cell foamed ceramic particles loaded with iron oxide.
[0011] The beneficial effects of this invention are: 1. Halloysite nanotubes (HNTs) are a natural nanotube-shaped silicate clay mineral found in nature. They are mainly composed of micron-sized hollow tubular structures. Halloysite is mixed with calcite, diatomaceous earth, and silicon carbide to prepare open-cell foamed ceramic particles. The open-cell foamed ceramic has many interconnected pores inside. The porous foamed ceramic sintered with halloysite also has a large number of micropores on the surface of the pore walls, resulting in a large specific surface area. Iron oxide catalyst is loaded on the surface and in the internal pores of the open-cell foamed ceramic, which can fully disperse the iron oxide and thus fully expose the active sites for the reaction of iron oxide with H2S, which is beneficial to improving the desulfurization accuracy of iron oxide.
[0012] 2. The open-cell foamed ceramic containing malachite also contains MnO. On the one hand, an appropriate amount of MnO loading provides more oxygen vacancies and surface hydroxyl groups for the desulfurizing agent, promoting the desulfurization reaction. Because Mn... 2+ A higher oxidation potential energy facilitates the forward reaction of H2S to elemental sulfur. On the other hand, the presence of Mn ions can interfere with the formation of iron oxide crystals. Mn ions embedding into the iron oxide crystals alters the crystal structure, resulting in smaller crystal particles. This allows the iron oxide to form a thinner desulfurizing agent layer on the surface of the open-cell foamed ceramic, maintaining a relatively large pore size even after loading with iron oxide, which is beneficial for the flow of H2S gas and increases the H2S removal efficiency. H2S combines with iron oxide to form FeS, thereby achieving the purpose of H2S removal. The desulfurizing agent in this application can be placed in water and regenerated using O2 bubbling. During catalyst regeneration, FeS is oxidized to elemental sulfur. Because the iron oxide layer in the open-cell foamed ceramic is thin, the generated elemental sulfur layer is also thin, preventing pore blockage of the desulfurizing agent and increasing its service life.
[0013] 3. The inner and outer surfaces of halloysites (HNTs) have different chemical compositions. The inner surface and tube ends are distributed with aluminum hydroxyl groups, which are positively charged, while the outer surface is mainly composed of siloxanes, which are negatively charged. Due to defects such as vacancies, it also contains a certain number of silanol groups. Acid treatment of halloysite can wash away part of the alumina layer inside the tube, increasing the inner diameter of the halloysite tube without destroying its intact tubular structure. This is beneficial for loading ZnS inside the halloysite tube. Loading ZnS using a vacuum negative pressure method allows ZnS to be loaded inside the halloysite tube wall. ZnS has an adsorption effect on elemental sulfur. During the desulfurizer regeneration process, FeS reacts with water and oxygen to generate iron oxide and elemental sulfur. The generated elemental sulfur can migrate to the halloysite tube wall under the attraction of ZnS, thereby re-exposing the active components of iron oxide. This ensures that the regenerated desulfurizer still maintains good desulfurization performance and can increase the number of regeneration cycles. Detailed Implementation
[0014] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Example 1
[0015] A method for preparing a desulfurizing agent that improves the air purification efficiency after decarbonization includes the following steps: S1. Prepare a 2 mol / L hydrochloric acid solution. Mix halloysite with a 3 mol / L hydrochloric acid solution and stir evenly at 80℃. Then, treat with ultrasound for 30 min. After the reaction, filter, dry, and grind into powder to obtain acid-modified halloysite powder. Mix the acid-modified halloysite powder with a 1 mol / L ZnS solution. The ZnS solution is prepared by mixing a 10 mol / L ZnSO4 solution with a 10 mol / L Na2S solution as a stabilizer. The volume ratio of ZnSO4 solution to Na2S solution is 1:50. Then, place the mixture in a vacuum dryer and maintain a vacuum state for 60 min. Open the valve of the vacuum dryer to vent. Repeat the vacuuming and venting process 5 times. After the loading is completed, centrifuge the mixture, precipitate, wash with a large amount of distilled water and then wash with dilute hydrochloric acid to remove ZnS outside the halloysite nanotubes. After drying, grind into powder to obtain ZnS-modified halloysite. S2. Mix 60 parts of modified halloysite, 15 parts of calcite, 15 parts of diatomite, 5 parts of MnO and 0.3 parts of silicon carbide and place them in a ball mill. Add water to the ball mill and wet grind for 60 minutes. Dry, granulate and sinter the wet-milled and uniformly mixed slurry. After sintering, open-cell foamed ceramic particles are obtained. S3. Prepare a 0.1 mol / L FeCl3·6H2O aqueous solution, add the open-cell foamed ceramic particles to the solution and stir thoroughly. Sonicate the mixed solution for 30 min, and then add a 1 mol / L KOH solution to the solution while stirring. Age the mixture of open-cell foamed ceramic and precipitate suspension at a constant temperature of 60℃ for 3 h, and then filter, wash, dry and sinter to obtain open-cell foamed ceramic particles loaded with iron oxide. Example 2
[0016] A method for preparing a desulfurizing agent that improves the air purification efficiency after decarbonization includes the following steps: S1. Prepare a 3 mol / L hydrochloric acid solution. Mix halloysite with the 3 mol / L hydrochloric acid solution and stir evenly at 60℃. Then, treat with ultrasound for 60 min. After the reaction, filter, dry, and grind into powder to obtain acid-modified halloysite powder. Mix the acid-modified halloysite powder with a 1 mol / L ZnS solution. The ZnS solution is prepared by mixing a 10 mol / L ZnSO4 solution with a 10 mol / L Na2S solution as a stabilizer. The volume ratio of ZnSO4 solution to Na2S solution is 1:50. Then, place the mixture in a vacuum dryer and maintain a vacuum state for 30 min. Open the valve of the vacuum dryer to vent. Repeat the vacuuming and venting process 3 times. After the loading is completed, centrifuge the mixture, precipitate, wash with a large amount of distilled water and then wash with dilute hydrochloric acid to remove ZnS outside the halloysite nanotubes. After drying, grind into powder to obtain ZnS-modified halloysite. S2. Mix 70 parts of modified halloysite, 10 parts of calcite, 20 parts of diatomite, 2 parts of MnO and 0.5 parts of silicon carbide and place them in a ball mill. Add water to the ball mill and wet grind for 30 minutes. Dry, granulate and sinter the wet-milled and uniformly mixed slurry. After sintering, open-cell foamed ceramic particles are obtained. S3. Prepare a 0.1 mol / L FeCl3·6H2O aqueous solution, add the open-cell foamed ceramic particles to the solution and stir thoroughly. Sonicate the mixed solution for 60 min, and then add a 1 mol / L KOH solution to the solution while stirring. Age the mixture of open-cell foamed ceramic and precipitate suspension at a constant temperature of 60℃ for 2 h, and then filter, wash, dry and sinter to obtain open-cell foamed ceramic particles loaded with iron oxide. Example 3
[0017] A method for preparing a desulfurizing agent that improves the air purification efficiency after decarbonization includes the following steps: S1. Mix 70 parts halloysite, 10 parts calcite, 20 parts diatomite, 2 parts MnO and 0.5 parts silicon carbide and place them in a ball mill. Add water to the ball mill and wet grind for 30 minutes. Dry, granulate and sinter the wet-milled and uniformly mixed slurry. After sintering, open-cell foamed ceramic particles are obtained. S2. Prepare a 0.1 mol / L FeCl3·6H2O aqueous solution, add the open-cell foamed ceramic particles to the solution and stir thoroughly. Sonicate the mixed solution for 60 min, and then add a 1 mol / L KOH solution to the solution while stirring. The mixture of open-cell foamed ceramic and precipitate suspension is aged at a constant temperature of 60℃ for 2 h. Then, filter, wash, dry and sinter to obtain open-cell foamed ceramic particles loaded with iron oxide. Example 4
[0018] A method for preparing a desulfurizing agent that improves the air purification efficiency after decarbonization includes the following steps: S1. Prepare a 3 mol / L hydrochloric acid solution. Mix halloysite with the 3 mol / L hydrochloric acid solution and stir evenly at 60℃. Then, treat with ultrasound for 60 min. After the reaction, filter, dry, and grind into powder to obtain acid-modified halloysite powder. Mix the acid-modified halloysite powder with a 1 mol / L ZnS solution. The ZnS solution is prepared by mixing a 10 mol / L ZnSO4 solution with a 10 mol / L Na2S solution as a stabilizer. The volume ratio of ZnSO4 solution to Na2S solution is 1:50. Then, place the mixture in a vacuum dryer and maintain a vacuum state for 30 min. Open the valve of the vacuum dryer to vent. Repeat the vacuuming and venting process 3 times. After the loading is completed, centrifuge the mixture, precipitate, wash with a large amount of distilled water and then wash with dilute hydrochloric acid to remove ZnS outside the halloysite nanotubes. After drying, grind into powder to obtain ZnS-modified halloysite. S2. Mix 70 parts of modified halloysite, 10 parts of calcite, 20 parts of diatomite and 0.5 parts of silicon carbide and place them in a ball mill. Add water to the ball mill and wet mill for 30 minutes. Dry, granulate and sinter the wet-milled and uniformly mixed slurry. After sintering, open-cell foamed ceramic particles are obtained. S3. Prepare a 0.1 mol / L FeCl3·6H2O aqueous solution, add the open-cell foamed ceramic particles to the solution and stir thoroughly. Sonicate the mixed solution for 60 min, and then add a 1 mol / L KOH solution to the solution while stirring. Age the mixture of open-cell foamed ceramic and precipitate suspension at a constant temperature of 60℃ for 2 h, and then filter, wash, dry and sinter to obtain open-cell foamed ceramic particles loaded with iron oxide. Example 5
[0019] A method for preparing a desulfurizing agent that improves the air purification efficiency after decarbonization includes the following steps: S1. Prepare a 3 mol / L hydrochloric acid solution. Mix halloysite with the 3 mol / L hydrochloric acid solution and stir evenly at 60℃. Then, treat with ultrasound for 60 min. After the reaction, filter, dry, and grind into powder to obtain acid-modified halloysite powder. Mix the acid-modified halloysite powder with a 1 mol / L ZnS solution. The ZnS solution is prepared by mixing a 10 mol / L ZnSO4 solution with a 10 mol / L Na2S solution as a stabilizer. The volume ratio of ZnSO4 solution to Na2S solution is 1:50. Then, place the mixture in a vacuum dryer and maintain a vacuum state for 30 min. Open the valve of the vacuum dryer to vent. Repeat the vacuuming and venting process 3 times. After the loading is completed, centrifuge the mixture, precipitate, wash with a large amount of distilled water and then wash with dilute hydrochloric acid to remove ZnS outside the halloysite nanotubes. After drying, grind into powder to obtain ZnS-modified halloysite. S2. Prepare a 0.1 mol / L FeCl3·6H2O aqueous solution, add ZnS modified malachite to the solution and stir thoroughly. Sonicate the mixed solution for 60 min, and then add 1 mol / L KOH solution to the solution while stirring. The mixture of open-cell foamed ceramic and precipitate suspension is aged at a constant temperature of 60℃ for 2 h. Then, filter, wash, dry and sinter to obtain malachite loaded with iron oxide.
[0020] Comparative Example Pure iron oxide is used as the desulfurizing agent.
[0021] Test data The desulfurizing agents in Examples 1-5 and the comparative example were tested using a fixed-bed dynamic adsorption device as described in Ji Ke's "Study on the Desulfurization and Regeneration Performance of Iron-Based Desulfurizing Agents at Room Temperature". The desulfurizing agent's ability to finely desulfurize H2S gas was tested. 0.1 ppm was taken as the breakthrough point of H2S in the outlet gas, and the amount of H2S adsorbed by the desulfurizing agent when the outlet gas reaches the breakthrough point was used as the evaluation index of the desulfurizing agent's desulfurization performance.
[0022] The desulfurizing agents from Examples 1-5 and the comparative example were regenerated four times using a wet regeneration test, and the desulfurization performance of the regenerated desulfurizing agents was then tested. The wet regeneration test involved removing the sulfidated desulfurizing agent from the reaction tube and immediately dispersing it in a container containing 100 mL of water. The regeneration reaction was carried out using O2 bubbling at a flow rate of 500 mL / min for 6 hours. The desulfurizing agent was then dried and backfilled into the fixed-bed dynamic adsorption device for desulfurization.
[0023] Table 1. H2S breakthrough adsorption capacity of desulfurizing agent before and after 4 regenerations
[0024] As shown in Table 1, the desulfurization effect of Examples 1-2 is much greater than that of the comparative example, indicating that the desulfurizer prepared by this invention has a better desulfurization effect. After four regenerations, the desulfurizer still retains more than 50% of its desulfurization effect. In Example 3, the malachite was not modified. The desulfurization effect before four regenerations was slightly lower than that of Example 1-2, but the desulfurization effect after four regenerations was much lower than that of Example 2, indicating that ZnS-modified malachite can significantly improve the regeneration effect of the desulfurizer. In Example 4, no MnO was added, and in Example 5, foamed ceramics were not used. The data in Table 1 show that the desulfurization and regeneration effects of Examples 4 and 5 are both lower than those of Example 2, indicating that adding MnO and preparing malachite into foamed ceramics can improve the desulfurization and regeneration effects.
Claims
1. A method for producing a desulfurizer for improving the purification degree of decarbonized purge gas, characterized by: Includes the following steps: S1. Acid-modified halloysite is loaded with ZnS by vacuum negative pressure method to obtain ZnS-modified halloysite; S2. Mix ZnS-modified halloysite, MnO, calcite, diatomite and silicon carbide and place them in a ball mill. Add water to the ball mill and wet mill for 30-60 minutes. Dry, granulate and sinter the wet-milled and uniformly mixed slurry. After sintering, open-cell foamed ceramic particles are obtained. S3. Iron oxide is loaded onto the open-cell foamed ceramic particles using a co-precipitation method to obtain an iron oxide-loaded open-cell foamed ceramic desulfurizer. The acid-modified halloysite powder is mixed with ZnS solution, and then the mixture is placed in a vacuum dryer and kept under vacuum for 30-60 minutes. The vacuum dryer valve is opened to release the air. The vacuuming and venting process is repeated 3-5 times. After the load is completed, the mixture is centrifuged, precipitated, washed with dilute hydrochloric acid, dried and ground into powder to obtain ZnS-modified halloysite. Step S3 includes: preparing FeCl3·6H2O aqueous solution, adding open-cell foamed ceramic particles to the solution and stirring thoroughly, ultrasonically treating the mixed solution for 30~60 min, then adding KOH solution to the solution while stirring, aging the mixture of open-cell foamed ceramic and precipitate suspension at a constant temperature of 60℃ for 2~3 h, then filtering, washing, drying and sintering to obtain open-cell foamed ceramic particles loaded with iron oxide.
2. The method for preparing a desulfurizing agent to improve the air purification efficiency after decarbonization according to claim 1, characterized in that: Step S1 includes: preparing a 2-3 mol / L hydrochloric acid solution, mixing halloysite with the hydrochloric acid solution, stirring evenly at 60-80℃, ultrasonically treating for 30-60 minutes, filtering, drying, and grinding into powder after the reaction is completed to obtain acid-modified halloysite powder.
3. The method for preparing a desulfurizing agent to improve the air purification efficiency after decarbonization according to claim 1, characterized in that: Step S2 includes 60-70 parts of modified halloysite, 10-15 parts of calcite, 15-20 parts of diatomite, and 0.3-0.5 parts of silicon carbide.
4. The method of claim 3, wherein the desulfurizing agent is prepared by adding the additive to the desulfurizing agent. Step S2 also includes 2 to 5 parts of MnO.
5. A desulfurizer for improving the purification degree of decarbonized purge gas, characterized by: The desulfurizing agent is prepared by any one of claims 1 to 4.