Iron-based desulfurizer and preparation method thereof

Abstract

The invention relates to the technical field of desulfurizing agents, and particularly discloses an iron-based desulfurizing agent and a preparation method thereof. The preparation method comprises the following steps: S1, mixing ferric salt, ferrous salt, manganese salt and zinc salt in water according to a molar ratio of (1.2-2.0): 1: (0.05-0.08): (0.03-0.05), heating to 35-45 DEG C, blowing air, adding an alkali solution, reacting for 20-30 minutes, controlling the pH value of the reaction endpoint to be 8.0-8.5, and carrying out solid-liquid separation, washing and drying to obtain a precursor; s2, uniformly mixing the precursor, a composite pore-foaming agent, a binder and an oxygen storage agent, molding, and drying at 80-115 DEG C to obtain an iron-based desulfurizer; the composite pore-foaming agent comprises ammonium bicarbonate and ammonium acetate. The iron-based desulfurizing agent prepared by the invention has relatively high sulfur capacity and regeneration cycle retention rate.

Description

Technical Field

[0001] This application relates to the technical field of desulfurizing agents, and more specifically, to an iron-based desulfurizing agent and its preparation method. Background Technology

[0002] As an important industrial fuel and chemical feedstock, coal gas purification is crucial for the stable operation of subsequent processes, equipment protection, and environmental protection. Hydrogen sulfide in coal gas is a common acidic and harmful impurity. It is not only toxic and corrosive, severely corroding pipelines, instruments, and production equipment, but it can also lead to catalyst poisoning and deactivation in subsequent processes and potentially cause sulfur oxide emissions. Therefore, efficient removal of hydrogen sulfide from coal gas is a key step in the coal gas purification process.

[0003] Currently, commonly used industrial desulfurization methods can be divided into two main categories: dry desulfurization and wet desulfurization. Dry desulfurization, with its simple process and high desulfurization precision, can operate at ambient or medium temperatures, making it particularly suitable for the fine desulfurization of medium- and low-sulfur content coal gas. Among various dry desulfurizing agents, iron-based desulfurizing agents have received considerable research and application due to their readily available raw materials, low cost, and renewability. However, practical applications have revealed some areas for improvement in existing iron-based desulfurizing agents. For example, the sulfur penetration capacity of some products still falls short of increasingly stringent fine desulfurization requirements; simultaneously, their mechanical strength, resistance to pulverization, and post-regeneration activity stability need further improvement. These factors, to some extent, limit their more economical and efficient application.

[0004] Patent application CN115814801A discloses a method for preparing an iron-based desulfurizing agent, comprising: mixing iron salt, calcium powder, alkali metal and binder evenly, extruding and molding, and drying to obtain a catalyst precursor; and treating the obtained catalyst precursor under high temperature water vapor mixed gas for 2 to 12 hours to obtain the finished catalyst.

[0005] In this technical solution, the components are first physically mixed and then treated with a high-temperature steam mixture. While this is beneficial for molding and improving strength, it also leads to uneven dispersion of the active components in the carrier. Many components are encapsulated or aggregated, making it difficult to form abundant and highly exposed active sites. This significantly reduces the effective contact area between the active phase and hydrogen sulfide gas and decreases the number of effective active centers per unit volume. Therefore, despite the high mechanical strength, the reaction efficiency is limited, resulting in a low overall sulfur capacity. Summary of the Invention

[0006] To address the issues of poor dispersibility and low sulfur capacity of existing iron-based desulfurizers, this application provides an iron-based desulfurizer and its preparation method.

[0007] In a first aspect, this application provides a method for preparing an iron-based desulfurizing agent, employing the following technical solution: A method for preparing an iron-based desulfurizing agent includes the following steps: S1: Iron salt, ferrous salt, manganese salt and zinc salt are mixed in water in a molar ratio of (1.2~2.0):1:(0.05~0.08):(0.03~0.05), heated to 35~45℃, air is bubbled in, an alkaline solution is added, and the reaction is carried out for 20~30 min. The pH at the end of the reaction is controlled at 8.0~8.5. The solid and liquid are separated, washed and dried to obtain the precursor. S2: Mix the precursor, composite pore-forming agent, binder and oxygen storage agent evenly, shape them, and dry them at 80~115℃ to obtain iron-based desulfurizer. The composite porogen includes ammonium bicarbonate and ammonium acetate.

[0008] In this technical solution, by controlling the molar ratio of ferric salts to ferrous salts and co-precipitating them in a low-oxygen atmosphere, ferrous ions are controlled to oxidize, thereby directionally synthesizing fine-grained and uniformly dispersed iron hydroxyl oxide. During this process, manganese and zinc ions precipitate simultaneously, uniformly mixing with iron ions at the atomic / ionic scale in the early stages of precipitation to form a composite (hydroxy)oxide phase. This composite effect effectively inhibits excessive growth of iron hydroxyl oxide grains, increases the specific surface area of ​​the material, and enhances the structural stability of its framework, ultimately obtaining a composite precursor with an ideal microstructure.

[0009] In the molding stage, a composite pore-forming agent and binder are introduced. After drying, ammonium bicarbonate and ammonium acetate decompose stepwise, constructing a well-developed and interconnected hierarchical pore structure within the desulfurizer. This significantly improves gas mass transfer efficiency and imparts sufficient mechanical strength to the particles. Furthermore, the added cerium-zirconium composite oxide acts as an oxygen storage and release component. During the regeneration stage, it regulates oxygen storage and release, promoting a gentler and more thorough conversion of iron sulfide species into active iron (hydroxy) oxides. It also inhibits active phase sintering and grain coarsening caused by localized over-oxidation or thermal effects, effectively delaying structural degradation of the active component during multiple cycles and improving regeneration stability. The entire process system integrates active phase structure regulation, hierarchical pore construction, and regeneration performance enhancement, ultimately producing a high-performance iron-based desulfurizer with high specific surface area, porous hydroxy iron oxide as the active component, and manganese and zinc elements uniformly dispersed within it.

[0010] Preferably, the volume fraction of oxygen in the air is 5% to 8%.

[0011] Preferably, in step S2, the drying process is carried out using a segmented drying process.

[0012] More preferably, in step S2, during the drying process, dry air is introduced.

[0013] Preferably, the mass ratio of the precursor, composite pore-forming agent, binder and oxygen storage agent is 100:(10~20):(10~15):(5~15).

[0014] Preferably, the oxygen storage agent is a cerium-zirconium composite oxide.

[0015] Preferably, the preparation method of the cerium-zirconium composite oxide includes the following steps: Cerium salt and zirconium salt were added to water at a molar ratio of (0.6~0.8):(0.2~0.4), mixed evenly, and the pH was adjusted to 9.5~10.5. After precipitation reaction at 50~60℃ for 1.5~2h, the mixture was transferred to a reaction vessel, heated to 120~150℃, and hydrothermally crystallized for 4~6h. After solid-liquid separation, washing, drying, calcination, and cooling, cerium-zirconium composite oxide was obtained.

[0016] Preferably, the roasting temperature is 500~600℃ and the time is 2~3h.

[0017] In this technical solution, cerium and zirconium salts are mixed at a specific molar ratio and co-precipitated under alkaline conditions, achieving preliminary homogeneous mixing of cerium and zirconium elements at the molecular level. Subsequent hydrothermal crystallization promotes the transformation of the amorphous precipitate into a cerium-zirconium composite oxide precursor with higher crystallinity and more uniform composition. This structure is beneficial for improving the phase stability of the final product. The final calcination process removes residual hydroxyl groups and water of crystallization, further consolidating the formation of the cerium-zirconium composite oxide with a stable crystal structure and high oxygen storage and release capacity.

[0018] Preferably, after adjusting the pH, a surfactant comprising 3% to 5% of the total mass of cerium salt and zirconium salt is added.

[0019] Preferably, the surfactant is polyethylene glycol 4000 or Tween 80.

[0020] In this technical solution, surfactants help to regulate the particle morphology and dispersibility of the precipitated products, which is beneficial for obtaining a final product with suitable specific surface area and particle morphology in the subsequent calcination step, thereby providing a structural basis for the oxygen storage material to perform its stable function.

[0021] Preferably, the iron-based desulfurizer is impregnated with an alkaline solution before use, the alkaline solution including ammonia, organic amine and water.

[0022] More preferably, before use, the iron-based desulfurizing agent is immersed in an alkaline solution, mixed for 2-3 hours, and then subjected to solid-liquid separation, washing, and drying.

[0023] Preferably, the alkaline solution contains 10% to 15% ammonia by mass and 5% to 10% organic amine by mass.

[0024] Preferably, the organic amine is at least one of ethylenediamine and triethanolamine.

[0025] In this technical solution, alkaline sites are introduced into the surface and pores of the desulfurizer through alkaline solution impregnation. This helps to enhance the initial chemical adsorption of acidic H2S molecules, optimize the reaction interface environment, and thus improve the reaction efficiency and deep desulfurization accuracy of the desulfurizer in the initial stage of operation.

[0026] Preferably, the binder is attapulgite.

[0027] Preferably, the binder is a modified binder, which is attapulgite co-modified with alkali (earth) metals and organic complexing agents.

[0028] Preferably, the method for preparing the modified adhesive includes the following steps: Mix attapulgite, alkali metal salt or alkaline earth metal salt, organic complexing agent and water evenly, heat to 55~65℃, mix for 1.5~2h, separate solid and liquid, age for 18~24h, dry, pulverize to obtain modified binder.

[0029] Preferably, the organic complexing agent is any one of citric acid, citrate, or tartrate.

[0030] More preferably, the organic complexing agent is sodium citrate or sodium tartrate.

[0031] Preferably, the alkali metal salt or alkaline earth metal salt is MgCl2 or KCl.

[0032] Preferably, the mass ratio of the attapulgite clay, alkali metal salt or alkaline earth metal salt, organic complexing agent and water is 100:(10~15):(3~5):(200~260).

[0033] In this technical solution, the modified binder is treated with alkali metal salts or alkaline earth metal salts and organic complexing agents to significantly enhance the mechanical strength and structural integrity of the particles. Simultaneously, its good dispersibility helps maintain the porous structure already formed by the active precursor. Secondly, this application provides an iron-based desulfurizing agent prepared using the above method.

[0034] In this technical solution, the desulfurizing agent uses high-specific-surface-area, porous iron hydroxyl oxide as the active component, in which manganese and zinc elements exist in a uniform composite form formed by the co-precipitation of precursors. After being mixed with a composite pore-forming agent, binder, and oxygen storage agent and granulated, this composite precursor undergoes drying and pore-forming treatment, constructing a well-developed, multi-level porous structure within the particles. The final product possesses high sulfur penetration capacity, excellent mechanical strength, and good regeneration stability, making it suitable for the fine desulfurization process of medium- and low-sulfur coal gas.

[0035] In summary, this application has the following beneficial effects: This application achieves the directional generation of ferric hydroxide and the control of its highly dispersed nanoscale structure through a co-precipitation process in a low-oxygen-content air atmosphere. The simultaneous precipitation of manganese and zinc ions further refines the grains, increases the specific surface area, and enhances the accessibility of active sites, which helps to improve the sulfur penetration capacity. The constructed hierarchical porous structure facilitates the mass transfer of reactant gases, thereby improving the efficiency of the desulfurization reaction. The oxygen storage and release function of the cerium-zirconium composite oxide can efficiently promote the regeneration of the desulfurizer, delay the structural collapse of the active components, and extend its service life. Attached Figure Description

[0036] Figure 1 The image shows the XRD pattern of the iron-based desulfurizer prepared in Example 1 of this application. Detailed Implementation

[0037] The present application will be further described in detail below with reference to the embodiments.

[0038] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.

[0039] Preparation Examples 1-3: Cerium-Zirconium Composite Oxides Preparation Example 1 The preparation method of the cerium-zirconium composite oxide in this example includes the following steps: Cerium nitrate hexahydrate and zirconium oxynitrate were added to deionized water at a molar ratio of 0.8:0.2 to prepare a mixed salt solution with a total concentration of 1.0 mol / L for each metal cation. Under stirring, 10% ammonia water was slowly added dropwise to adjust the pH to 9.5. After precipitation reaction at 50℃ for 2 hours, the slurry was transferred to a reaction vessel, heated to 120℃, and hydrothermally crystallized for 6 hours. After centrifugation, the mixture was washed three times with deionized water, vacuum dried at 110℃ to constant weight, transferred to a muffle furnace, heated to 500℃ at a heating rate of 5℃ / min, calcined for 3 hours, and cooled to room temperature with the furnace to obtain cerium-zirconium composite oxide.

[0040] Preparation Example 2 The preparation method of the cerium-zirconium composite oxide in this example includes the following steps: Cerium nitrate hexahydrate and zirconium oxynitrate were added to deionized water at a molar ratio of 0.6:0.4, followed by the addition of Tween 80 at 5% of the total mass of the two compounds, to prepare a mixed salt solution with a total metal cation concentration of 1.0 mol / L. Ammonia solution with a mass fraction of 10% was slowly added dropwise under stirring to adjust the pH to 10.5. After precipitation at 60°C for 1.5 h, the slurry was transferred to a reaction vessel, heated to 150°C, and hydrothermally crystallized for 4 h. After centrifugation, the mixture was washed three times with deionized water, vacuum dried at 110°C to constant weight, transferred to a muffle furnace, heated to 600°C at a rate of 5°C / min, calcined for 2 h, and then cooled to room temperature in the furnace to obtain cerium-zirconium composite oxide.

[0041] Preparation Example 3 The preparation method of the cerium-zirconium composite oxide in this example includes the following steps: Cerium nitrate hexahydrate and zirconium oxynitrate were added to deionized water at a molar ratio of 0.7:0.3, followed by the addition of polyethylene glycol 4000 at 3% of the total mass of cerium nitrate hexahydrate and zirconium oxynitrate, to prepare a mixed salt solution with a total concentration of 1.0 mol / L for each metal cation. Ammonia solution with a mass fraction of 10% was slowly added dropwise under stirring to adjust the pH to 10.0. After precipitation at 55°C for 2 hours, the slurry was transferred to a reaction vessel, heated to 140°C, and hydrothermally crystallized for 5 hours. After centrifugation, the mixture was washed three times with deionized water, vacuum dried at 110°C to constant weight, transferred to a muffle furnace, heated to 550°C at a rate of 5°C / min, and calcined for 2.5 hours. The mixture was then cooled to room temperature in the furnace to obtain cerium-zirconium composite oxide.

[0042] Example 1 The preparation method of the iron-based desulfurizing agent in this embodiment includes the following steps: S1: Ferric nitrate nonahydrate, ferrous nitrate, manganese nitrate hexahydrate, and zinc nitrate hexahydrate were mixed in deionized water at a molar ratio of 1.2:1:0.05:0.03 to prepare a mixed salt solution with a total concentration of 1.0 mol / L of each metal cation. The solution was heated to 35°C, and oxygen-deficient air with a volume fraction of 6% was bubbled in at a rate of 0.1 L / min. Under stirring, ammonia solution with a mass fraction of 15% was slowly added dropwise, and the dropping rate was controlled so that the pH of the system slowly rose to 8.0 within 25 min. The rate of bubbling in the oxygen-deficient air was adjusted to 0.3 L / min, and the reaction was continued at this pH for 25 min. The reaction slurry was filtered by pressure, washed with deionized water, dried at 90°C for 1 h, and ground through a 100-mesh standard sieve to obtain the precursor. S2: Weigh the precursor obtained from S1, the composite pore-forming agent, attapulgite, and the cerium-zirconium composite oxide obtained from Preparation Example 1 in a mass ratio of 100:10:10:5, place them in a high-speed mixer, mix for 10 min, then spray in an appropriate amount of deionized water, extrude into shape, cut into pellets, transfer to a drying oven, and pass dry air through at 0.3 L / min for programmed temperature drying: heat to 80℃ at 1℃ / min, hold for 1 h, then continue to heat to 115℃ at a heating rate of 1℃ / min, and dry for 1 h to obtain the iron-based desulfurizing agent.

[0043] The composite porogen includes ammonium bicarbonate and ammonium acetate, with a mass ratio of 1:1.

[0044] Example 2 The preparation method of the iron-based desulfurizing agent in this embodiment includes the following steps: S1: Ferric nitrate nonahydrate, ferrous nitrate, manganese nitrate hexahydrate, and zinc nitrate hexahydrate were mixed in deionized water at a molar ratio of 2.0:1:0.08:0.05 to prepare a mixed salt solution with a total concentration of 1.0 mol / L for each metal cation. The solution was heated to 45°C, and oxygen-deficient air with a volume fraction of 5% was bubbled in at a rate of 0.1 L / min. Under stirring, ammonia solution with a mass fraction of 15% was slowly added dropwise, and the dropping rate was controlled so that the pH of the system slowly rose to 8.0 within 25 min. The bubble rate of oxygen-deficient air was adjusted to 0.3 L / min, and the reaction was continued at this pH for 20 min. The reaction slurry was filtered by pressure, washed with deionized water, dried at 90°C for 1 h, and ground through a 100-mesh standard sieve to obtain the precursor. S2: Weigh the precursor obtained from S1, the composite pore-forming agent, the attapulgite clay, and the cerium-zirconium composite oxide obtained from Preparation Example 2 in a mass ratio of 100:20:15:15. Place them in a high-speed mixer and mix for 10 min. Then spray in an appropriate amount of deionized water, extrude into shape, cut into pellets, transfer to a drying oven, and pass dry air through at 0.3 L / min for programmed temperature drying: heat up to 80°C at 1°C / min, hold for 1 h, and then continue to heat up to 115°C at a heating rate of 1°C / min and dry for 1 h to obtain the iron-based desulfurizing agent.

[0045] The composite porogen includes ammonium bicarbonate and ammonium acetate, with a mass ratio of 1:1.

[0046] Example 3 The preparation method of the iron-based desulfurizing agent in this embodiment includes the following steps: S1: Ferric nitrate nonahydrate, ferrous nitrate, manganese nitrate hexahydrate, and zinc nitrate hexahydrate were mixed in deionized water at a molar ratio of 1.5:1:0.07:0.04 to prepare a mixed salt solution with a total concentration of 1.0 mol / L for each metal cation. The solution was heated to 40°C, and oxygen-deficient air with an oxygen volume fraction of 8% was bubbled in at a rate of 0.1 L / min. Under stirring, ammonia solution with a mass fraction of 15% was slowly added dropwise, and the dropping rate was controlled so that the pH of the system slowly rose to 8.5 within 25 min. The bubbling rate of oxygen-deficient air was adjusted to 0.3 L / min, and the reaction was continued at this pH for 30 min. The reaction slurry was filtered by pressure, washed with deionized water, dried at 90°C for 1 h, and ground through a 100-mesh standard sieve to obtain the precursor. S2: Weigh the precursor obtained from S1, the composite pore-forming agent, attapulgite clay, and the cerium-zirconium composite oxide obtained in Preparation Example 3 according to a mass ratio of 100:15:12:10. Place them in a high-speed mixer and mix for 10 min. Then spray in an appropriate amount of deionized water, extrude into shape, cut into pellets, transfer to a drying oven, and pass dry air through at 0.3 L / min for programmed temperature drying: heat up to 80°C at 1°C / min, hold for 1 h, and then continue to heat up to 115°C at a heating rate of 1°C / min and dry for 1 h to obtain an iron-based desulfurizing agent.

[0047] The composite porogen includes ammonium bicarbonate and ammonium acetate, with a mass ratio of 1:1.

[0048] Example 4 The difference between this embodiment and embodiment 3 is as follows: Before using iron-based desulfurizers, the following pretreatment steps are also required: The iron-based desulfurizer from Example 3 was immersed in an alkaline solution with a solid-liquid ratio of 1g:5mL. The mixture was stirred at 200rpm for 3 hours, filtered, rinsed twice with deionized water, and dried at 90℃ for 1 hour to obtain the final product.

[0049] The alkaline solution includes ammonia, ethylenediamine, and deionized water, with the ammonia having a mass fraction of 10% and the ethylenediamine having a mass fraction of 5%.

[0050] Everything else is the same as in Example 3.

[0051] Example 5 The difference between this embodiment and embodiment 3 is as follows: Before using iron-based desulfurizers, the following pretreatment steps are also required: The iron-based desulfurizer from Example 3 was immersed in an alkaline solution with a solid-liquid ratio of 1g:5mL. The mixture was stirred at 200rpm for 2 hours, filtered, rinsed twice with deionized water, and dried at 90℃ for 1 hour to obtain the final product.

[0052] The alkaline solution includes ammonia, ethylenediamine, triethanolamine, and deionized water, with the mass fraction of ammonia being 15%, ethylenediamine being 5%, and triethanolamine being 5%.

[0053] Everything else is the same as in Example 3.

[0054] Example 6 The difference between this embodiment and embodiment 3 is as follows: The adhesive is a modified adhesive, and the preparation method of the modified adhesive includes the following steps: Attapulgite clay, MgCl2, sodium citrate, and deionized water were added to a reactor in a mass ratio of 100:10:3:200. The mixture was stirred at 500 rpm for 1 hour, heated to 55°C, and mixed for another 2 hours. After pressing and filtration to obtain a wet filter cake, the cake was aged at 25°C for 24 hours, transferred to a drying oven, and dried at 80°C to constant weight. The cake was then ground and passed through a 200-mesh standard sieve to obtain the modified binder.

[0055] Everything else is the same as in Example 3.

[0056] Example 7 The difference between this embodiment and embodiment 5 is as follows: The adhesive is a modified adhesive, and the preparation method of the modified adhesive includes the following steps: Attapulgite, KCl, sodium tartrate, and deionized water were added to a reactor in a mass ratio of 100:15:5:260. The mixture was stirred at 500 rpm for 1 hour, heated to 65°C, and mixed for another 1.5 hours. After pressing and filtration to obtain a wet filter cake, the cake was aged at 25°C for 18 hours, transferred to a drying oven, and dried at 80°C to constant weight. The cake was then ground and passed through a 200-mesh standard sieve to obtain the modified binder.

[0057] The rest is the same as in Example 5.

[0058] Comparative Example 1 The difference between this comparative example and Example 1 is as follows: No cerium-zirconium composite oxide was added; Everything else is the same as in Example 1.

[0059] Comparative Example 2 The difference between this comparative example and Example 1 is as follows: S1: Ferric nitrate nonahydrate, manganese nitrate hexahydrate, and zinc nitrate hexahydrate were mixed in deionized water at a molar ratio of 2.2:0.05:0.03 to prepare a mixed salt solution with a total concentration of 1.0 mol / L for each metal cation. The solution was heated to 35°C, and oxygen-deficient air with a volume fraction of 6% was bubbled in at a rate of 0.1 L / min. Under stirring, ammonia solution with a mass fraction of 15% was slowly added dropwise, and the dropping rate was controlled so that the pH of the system slowly rose to 8.0 within 25 min. The rate of bubbling in the oxygen-deficient air was adjusted to 0.3 L / min, and the reaction was continued at this pH for 25 min. The reaction slurry was filtered by pressure, washed with deionized water, dried at 90°C for 1 h, and ground through a 100-mesh standard sieve to obtain the precursor. Everything else is the same as in Example 1.

[0060] Comparative Example 3 The difference between this comparative example and Example 1 is as follows: S1: Ferric nitrate nonahydrate, ferrous nitrate, and zinc nitrate hexahydrate were mixed in deionized water at a molar ratio of 1.2:1:0.03 to prepare a mixed salt solution with a total concentration of 1.0 mol / L for each metal cation. The solution was heated to 35°C, and oxygen-deficient air with a volume fraction of 6% was bubbled in at a rate of 0.1 L / min. Under stirring, ammonia solution with a mass fraction of 15% was slowly added dropwise, and the dropping rate was controlled so that the pH of the system slowly rose to 8.0 within 25 min. The rate of bubbling in the oxygen-deficient air was adjusted to 0.3 L / min, and the reaction was continued at this pH for 25 min. The reaction slurry was filtered by pressure, washed with deionized water, dried at 90°C for 1 h, and ground through a 100-mesh standard sieve to obtain the precursor. Everything else is the same as in Example 1.

[0061] Comparative Example 4 The difference between this comparative example and Example 1 is as follows: S1: Ferric nitrate nonahydrate and ferrous nitrate were mixed in deionized water at a molar ratio of 1.2:1 to prepare a mixed salt solution with a total concentration of 1.0 mol / L of each metal cation. The solution was heated to 35°C. Oxygen-free air with a volume fraction of 6% was bubbled in at a rate of 0.1 L / min. Under stirring, ammonia solution with a mass fraction of 15% was slowly added dropwise. The dropping rate was controlled so that the pH of the system slowly rose to 8.0 within 25 min. The bubble rate of oxygen-free air was adjusted to 0.3 L / min, and the reaction was continued at this pH for 25 min. The reaction slurry was filtered by pressure, washed with deionized water, dried at 90°C for 1 h, and ground through a 100-mesh standard sieve to obtain the precursor. Everything else is the same as in Example 1.

[0062] Comparative Example 5 The difference between this comparative example and Example 1 is as follows: S2: Weigh the precursor obtained from S1, ammonium bicarbonate, attapulgite, and cerium-zirconium composite oxide obtained from Preparation Example 1 in a mass ratio of 100:10:10:5, place them in a high-speed mixer, mix for 10 min, then spray in an appropriate amount of deionized water, extrude into shape, cut into pellets, transfer to a drying oven, and pass dry air through at 0.3 L / min for programmed temperature drying: heat to 80℃ at 1℃ / min, hold for 2 h, then continue to heat to 115℃ at a heating rate of 1℃ / min, and dry for 1 h to obtain an iron-based desulfurizing agent.

[0063] Everything else is the same as in Example 1.

[0064] Performance testing (1) Sample pretreatment: Before testing, the iron-based desulfurizers prepared in Examples 1-7 and Comparative Examples 1-5 were placed in a forced-air drying oven and dried at 80°C for 30 min. Then, they were placed in a desiccator and cooled to room temperature for later use. (2) Specific surface area and pore structure analysis: The specific surface area and porosity were measured using a specific surface area and porosity analyzer at liquid nitrogen temperature (77K). Before the test, the sample was degassed under vacuum at 50℃ for 4h. The test results are shown in Table 1. (3) Mechanical strength test: The radial crushing force of each particle was measured using a particle strength tester. The results are expressed as average crushing force. The tested particles were uniformly selected as Ф4mm×15mm. The test results are shown in Table 1. (4) Desulfurization performance evaluation: Dynamic breakthrough experiments were conducted using a micro fixed-bed reactor, and the tests were divided into two groups: Basic performance testing: Simulated feed gas composition (volume fraction): hydrogen sulfide concentration 100 ppm, water vapor 1%, the remainder nitrogen, space velocity 1000 h⁻¹ -1 The test temperature was 80℃. The breakthrough endpoint was defined as the H2S concentration at the reactor outlet reaching 1ppm twice consecutively. The breakthrough sulfur capacity was calculated, and the test results are shown in Table 1. Industrial simulation test: Simulated feed gas composition (volume fraction): hydrogen sulfide concentration 100 ppm, carbon monoxide 20%, carbon dioxide 10%, hydrogen 2%, water vapor 1%, the remainder is nitrogen, space velocity 1000 h⁻¹ -1 The test temperature was 80℃. The breakthrough endpoint was defined as the H2S concentration at the reactor outlet reaching 1ppm twice consecutively. The breakthrough sulfur capacity was calculated, and the test results are shown in Table 1. (5) Regeneration cycle stability test: The desulfurizing agent that has completed the 80℃ industrial simulated desulfurization test and achieved breakthrough was purged in a nitrogen atmosphere for 30 min, and then switched to a regeneration atmosphere (oxygen volume fraction of 5%, water vapor volume fraction of 5%, and the remainder nitrogen). The temperature was increased to 260℃ at a programmed rate of 2℃ / min. The outlet O2 concentration was restored to the inlet level, and it was confirmed that no byproducts such as SO2 were generated in the outlet gas. Based on the breakthrough sulfur capacity of the first cycle, the sulfur capacity retention rate after the 5th cycle was calculated as the evaluation index of regeneration stability. The test results are shown in Table 1.

[0065] Table 1. Performance test data of iron-based desulfurizers prepared in Examples 1-7 and Comparative Examples 1-5

[0066] The performance test data of the iron-based desulfurizers in Examples 1-3 show that by adjusting the molar ratio of ferric salts to ferrous salts, low-oxygen air, and the pH at the end of the precipitation reaction, and by cooperating with the synergistic effect of a specific ratio of manganese salts and zinc salts, an iron-based desulfurizer with high specific surface area, suitable pore structure, and sufficient mechanical strength can be successfully prepared to meet the performance requirements of basic desulfurization scenarios.

[0067] Combination Figure 1 XRD pattern analysis revealed that a desulfurizing agent precursor with iron hydroxide as the main active phase was successfully prepared under the described low-temperature precipitation and drying process. Its characteristic diffraction peaks were mainly located around 26.7° and 35.2°; the secondary strong peaks at 29.0° and 47.9° corresponded to Ce. 0.8 Zr 0.2 The characteristic crystal planes of O2 solid solution, with their systematic high-angle shift relative to the standard peak of pure CeO2, indicate that Zr 4+ It has been successfully embedded in the CeO2 lattice to form a solid solution, which can effectively suppress grain agglomeration.

[0068] The performance test data of the iron-based desulfurizers in Example 1 and Comparative Examples 1-5 show that the absence of cerium-zirconium composite oxygen storage agent directly leads to a significant reduction in the regeneration cycle stability of the desulfurizer; the absence of ferrous salt and the use of a single pore-forming agent result in a relatively small specific surface area and pore volume of the desulfurizer, and a significant reduction in sulfur capacity and regeneration cycle stability. In addition, the mechanical strength of the desulfurizer lacking ferrous salt is reduced; the absence of manganese or the simultaneous absence of manganese and zinc elements leads to a simultaneous decrease in desulfurization activity and regeneration cycle stability.

[0069] As can be seen from the performance test data of the iron-based desulfurizers in Examples 4-7, alkaline solution impregnation treatment can effectively optimize the distribution of active sites on the surface of the desulfurizer and significantly improve its desulfurization capacity in simulated complex industrial atmospheres; the binder modification technology can further enhance the structural integrity and activity retention rate of the desulfurizer after multiple regeneration cycles while maintaining high desulfurization capacity, thereby achieving a synergistic improvement in desulfurization performance and cycle stability.

[0070] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing an iron-based desulfurizing agent, characterized in that, Includes the following steps: S1: Iron salt, ferrous salt, manganese salt and zinc salt are mixed in water in a molar ratio of (1.2~2.0):1:(0.05~0.08):(0.03~0.05), heated to 35~45℃, air is bubbled in, an alkaline solution is added, and the reaction is carried out for 20~30 min. The pH at the end of the reaction is controlled at 8.0~8.

5. The solid and liquid are separated, washed and dried to obtain the precursor. S2: Mix the precursor, composite pore-forming agent, binder and oxygen storage agent evenly, shape them, and dry them at 80~115℃ to obtain iron-based desulfurizer; The composite porogen includes ammonium bicarbonate and ammonium acetate.

2. The method for preparing the iron-based desulfurizing agent according to claim 1, characterized in that, The oxygen volume fraction in the air is 5% to 8%.

3. The method for preparing the iron-based desulfurizing agent according to claim 1, characterized in that, The mass ratio of the precursor, composite porogen, binder and oxygen storage agent is 100:(10~20):(10~15):(5~15).

4. The method for preparing the iron-based desulfurizing agent according to claim 1, characterized in that, The oxygen storage agent is a cerium-zirconium composite oxide.

5. The method for preparing the iron-based desulfurizing agent according to claim 4, characterized in that, The preparation method of the cerium-zirconium composite oxide includes the following steps: Cerium salt and zirconium salt were added to water at a molar ratio of (0.6~0.8):(0.2~0.4), mixed evenly, and the pH was adjusted to 9.5~10.

5. After precipitation reaction at 50~60℃ for 1.5~2h, the mixture was transferred to a reaction vessel, heated to 120~150℃, and hydrothermally crystallized for 4~6h. After solid-liquid separation, washing, drying, calcination, and cooling, cerium-zirconium composite oxide was obtained.

6. The method for preparing the iron-based desulfurizing agent according to claim 5, characterized in that, After adjusting the pH, a surfactant is added, comprising 3% to 5% of the total mass of cerium and zirconium salts.

7. The method for preparing the iron-based desulfurizing agent according to claim 1, characterized in that, Before use, the iron-based desulfurizer is impregnated with an alkaline solution, which includes ammonia, organic amines and water.

8. The method for preparing the iron-based desulfurizing agent according to claim 1, characterized in that, The binder is attapulgite.

9. The method for preparing the iron-based desulfurizing agent according to claim 1, characterized in that, The adhesive is a modified adhesive, and the preparation method of the modified adhesive includes the following steps: Mix attapulgite, alkali metal salt or alkaline earth metal salt, organic complexing agent and water evenly, heat to 55~65℃, mix for 1.5~2h, separate solid and liquid, age for 18~24h, dry, pulverize to obtain modified binder.

10. An iron-based desulfurizing agent prepared by the method of any one of claims 1 to 9.

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