Iron-based desulfurizer and method for preparing the same

Abstract

The application relates to the technical field of desulfurizers, and particularly discloses an iron-based desulfurizer and a preparation method thereof. The preparation method of the iron-based desulfurizer comprises the following steps: S1: mixing iron salt, ferrous salt, manganese salt and zinc salt in water in a molar ratio of (1.2-2.0):1:(0.05-0.08):(0.03-0.05), heating to 35-45 DEG C, blowing in air, adding an alkali solution, reacting for 20-30 min, and controlling the final pH of the reaction to be 8.0-8.5, then performing solid-liquid separation, washing, drying, and obtaining a precursor; and S2: uniformly mixing the precursor, a composite pore-forming agent, a binder and an oxygen storage agent, shaping, drying at 80-115 DEG C, and obtaining the iron-based desulfurizer; the composite pore-forming agent comprises ammonium bicarbonate and ammonium acetate. The iron-based desulfurizer prepared according to the application has high sulfur capacity and regeneration cycle retention rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of desulfurizers, and more particularly to an iron-based desulfurizer and a preparation method thereof. BACKGROUND

[0002] Coal gas is an important industrial fuel and chemical raw material, and its purification treatment is crucial for the stable operation of subsequent processes, equipment protection and environmental protection. Hydrogen sulfide in coal gas is a common harmful impurity, which not only has toxicity and corrosiveness, can seriously corrode pipelines, instruments and production equipment, but also can cause catalyst poisoning and deactivation in subsequent sections, and may cause sulfur oxide emission pollution. Therefore, efficient removal of hydrogen sulfide in coal gas is a key link in the coal gas purification process.

[0003] At present, the commonly used desulfurization methods in industry can be divided into two categories: dry desulfurization and wet desulfurization. Among them, the dry desulfurization process is simple, has high desulfurization precision, and can be operated at normal temperature or medium temperature, especially suitable for fine desulfurization of medium and low sulfur content coal gas. Among various dry desulfurizers, iron-based desulfurizers have been studied and applied more due to the easy availability of raw materials, lower cost, and renewability. However, in practical application, it is found that the existing iron-based desulfurizers still have some room for improvement. For example, the breakthrough sulfur capacity of some products is still difficult to meet the increasingly stringent fine desulfurization requirements; at the same time, its mechanical strength, anti-pulverization ability and activity stability after regeneration also need to be improved. These factors limit its more economical and efficient application to some extent.

[0004] The patent application file with publication number CN115814801A discloses a preparation method of an iron-based desulfurizer, which comprises: uniformly mixing iron salt, calcium powder, alkali metal and binder, extruding and molding, and drying to obtain a catalyst precursor; and treating the obtained catalyst precursor under the condition of high-temperature water vapor mixed gas for 2-12 hours to obtain a finished catalyst.

[0005] In this technical solution, the components are first physically mixed, and then treated with high-temperature water vapor mixed gas. Although this is beneficial to molding and improving strength, it also leads to uneven dispersion of active components in the carrier, which are often wrapped or aggregated, making it difficult to form rich and highly exposed active sites. This significantly reduces the effective contact area between the active phase and hydrogen sulfide gas, and reduces the number of effective active centers in unit volume. Therefore, although the mechanical strength is high, the reaction efficiency is limited, resulting in low overall sulfur capacity. SUMMARY

[0006] In order to solve the problems of poor dispersion of active components and low sulfur capacity of existing iron-based desulfurizers, the present application provides an iron-based desulfurizer and a preparation method thereof.

[0007] In a first aspect, the application provides a preparation method of an iron-based desulfurizer, which adopts the following technical scheme:

[0008] A preparation method of an iron-based desulfurizer, comprising the following steps:

[0009] S1: mixing iron salt, ferrous salt, manganese salt and zinc salt in water in a molar ratio of (1.2-2.0):1:(0.05-0.08):(0.03-0.05), heating to 35-45℃, blowing in air, adding an alkali solution, reacting for 20-30 min, and controlling the final pH of the reaction to be 8.0-8.5, solid-liquid separation, washing, drying, and obtaining a precursor;

[0010] S2: uniformly mixing the precursor, a composite pore-forming agent, a binder and an oxygen storage agent, shaping, and drying at 80-115℃ to obtain an iron-based desulfurizer;

[0011] The composite pore-forming agent comprises ammonium bicarbonate and ammonium acetate.

[0012] In the technical scheme, by controlling the molar ratio of iron salt and ferrous salt and performing co-precipitation in an atmosphere of low-oxygen-content air, the ferrous ions are controllably oxidized, so that iron oxyhydroxide with small crystal grains and uniform dispersion is directionally synthesized. In this process, manganese ions and zinc ions are simultaneously precipitated and uniformly mixed with iron ions in the early stage of precipitation, i.e. on the atomic / ion scale, to form a composite (oxy)hydroxide phase. The composite effect can effectively inhibit the excessive growth of iron oxyhydroxide crystal grains, improve the specific surface area of the material, and enhance the structural stability of the skeleton, so that a composite precursor with ideal micro-morphology is finally obtained.

[0013] In the shaping stage, the composite pore-forming agent and the binder are introduced, and after drying, the ammonium bicarbonate and the ammonium acetate are stepwise decomposed to build through and developed multi-level pores in the desulfurizer, significantly improving the gas mass transfer efficiency and giving the particles sufficient mechanical strength. In addition, the added cerium-zirconium composite oxide as an oxygen storage and release component promotes the more moderate and complete conversion of iron sulfide species into active iron (oxy)hydroxide in the regeneration stage by regulating the storage and release of oxygen, and inhibits the sintering and grain coarsening of the active phase due to local excessive oxidation or thermal effect, effectively delaying the structural degradation of the active component in multiple cycles and improving the regeneration stability. The whole process system integrates the structure regulation of the active phase, the construction of multi-level pores and the performance enhancement of regeneration, and finally obtains a high-performance iron-based desulfurizer with high specific surface area and porous iron oxyhydroxide as the active main body, and manganese and zinc elements uniformly compounded in a highly dispersed form.

[0014] Preferably, the volume fraction of oxygen in the air is 5%-8%.

[0015] Preferably, in step S2, the drying is performed by using a staged drying process.

[0016] Further preferably, in the step S2, dry air is introduced during the drying.

[0017] Preferably, the mass ratio of the precursor, the composite pore-forming agent, the binder and the oxygen storage agent is 100:(10~20):(10~15):(5~15).

[0018] Preferably, the oxygen storage agent is a cerium-zirconium composite oxide.

[0019] Preferably, the preparation method of the cerium-zirconium composite oxide comprises the following steps:

[0020] cerium salt and zirconium salt are added into water in a molar ratio of (0.6~0.8):(0.2~0.4), mixed uniformly, the pH is adjusted to 9.5~10.5, and then the precipitation reaction is carried out at 50~60℃ for 1.5~2h, and then the reaction kettle is transferred, the temperature is raised to 120~150℃, and then the hydrothermal crystallization is carried out for 4~6h, and then the solid-liquid separation is carried out, and then the washing, drying and calcination are carried out, and then the cerium-zirconium composite oxide is obtained after cooling.

[0021] Preferably, the calcination temperature is 500~600℃, and the calcination time is 2~3h.

[0022] In the technical solution, the cerium salt and the zirconium salt are mixed in a specific molar ratio and co-precipitated under alkaline conditions, which realizes the preliminary uniform mixing of cerium and zirconium elements at the molecular level. The subsequent hydrothermal crystallization treatment promotes the transformation of the amorphous precipitate into a cerium-zirconium composite oxide precursor with higher crystallinity and uniform composition, which is beneficial to improving the phase stability of the final product. The final calcination process not only removes residual hydroxyl groups and crystal water, but also further consolidates the formation of cerium-zirconium composite oxide with stable crystal structure and high oxygen storage and release capacity.

[0023] Preferably, after adjusting the pH, a surfactant is added, and the mass of the surfactant accounts for 3%~5% of the total mass of the cerium salt and the zirconium salt.

[0024] Preferably, the surfactant is polyethylene glycol 4000 or Tween 80.

[0025] In the technical solution, the surfactant helps to regulate the particle morphology and dispersibility of the precipitate, which is beneficial to obtaining a final product with appropriate specific surface area and particle morphology in the subsequent calcination step, thereby providing a structural basis for the stable function of the oxygen storage material.

[0026] Preferably, before use, the iron-based desulfurizer is treated by impregnation with an alkaline solution, and the alkaline solution comprises ammonia water, organic amine and water.

[0027] Further preferably, before use, the iron-based desulfurizer is impregnated in an alkaline solution, mixed for 2~3h, solid-liquid separated, washed and dried.

[0028] Preferably, the mass fraction of ammonia water in the alkaline solution is 10% to 15%, and the mass fraction of the organic amine is 5% to 10%.

[0029] Preferably, the organic amine is at least one of ethylenediamine and triethanolamine.

[0030] In the technical solution, the alkaline sites are introduced on the surface and in the pores of the desulfurizer through the impregnation treatment of the alkaline solution. This helps to strengthen the initial chemical adsorption of the 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.

[0031] Preferably, the binder is attapulgite.

[0032] Preferably, the binder is a modified binder, and the modified binder is attapulgite co-modified by an alkaline (earth) metal and an organic complexing agent.

[0033] Preferably, the preparation method of the modified binder comprises the following steps:

[0034] The attapulgite, the alkaline or alkaline earth metal salt, the organic complexing agent, and water are uniformly mixed, heated to 55 to 65℃, mixed for 1.5 to 2h, solid-liquid separated, aged for 18 to 24h, dried, and crushed to obtain the modified binder.

[0035] Preferably, the organic complexing agent is any one of citric acid, citrate, or tartrate.

[0036] Further preferably, the organic complexing agent is sodium citrate or sodium tartrate.

[0037] Preferably, the alkaline or alkaline earth metal salt is MgCl2 or KCl.

[0038] Preferably, the mass ratio of the attapulgite, the alkaline or alkaline earth metal salt, the organic complexing agent, and water is 100:(10 to 15):(3 to 5):(200 to 260).

[0039] In the technical solution, the modified binder is treated by the alkaline or alkaline earth metal salt and the organic complexing agent to significantly enhance the mechanical strength and structural integrity of the particles, and its good dispersibility is conducive to maintaining the porous structure of the active precursor formed. In a second aspect, the application provides an iron-based desulfurizer prepared by the above preparation method.

[0040] In the technical solution, the desulfurizer takes high specific surface area and porous iron oxyhydroxide as an active main body, and manganese and zinc elements are in a uniform composite form formed by co-precipitation of a precursor. After the composite precursor is mixed with a composite pore-forming agent, a binder and an oxygen storage agent to form granules, and then dried and pore-formed, a developed multi-stage pore structure is constructed inside the granules. The final product has high sulfur breakthrough capacity, excellent mechanical strength and good regeneration stability, and is suitable for fine desulfurization of medium and low sulfur coal gas.

[0041] In summary, the present application has the following beneficial effects:

[0042] The present application realizes directional generation of iron oxyhydroxide and regulation of nanoscale high dispersion structure through a co-precipitation process under a low-oxygen-content air atmosphere; synchronous precipitation of manganese and zinc ions further refines the crystal grains, increases the specific surface area, and increases the accessibility of active sites, which helps to improve the sulfur breakthrough capacity; the constructed multi-stage pore structure is beneficial to mass transfer of reaction gas, and improves the efficiency of desulfurization reaction; the oxygen storage and release function of cerium-zirconium composite oxide can efficiently promote regeneration of the desulfurizer, delay structural collapse of the active components, and prolong the service life. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 The XRD pattern of the iron-based desulfurizer prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0044] The present application is further described below in conjunction with examples.

[0045] The raw materials of the examples and comparative examples of the present application are all ordinary commercial products except for special indications.

[0046] Preparation Examples 1-3 of cerium-zirconium composite oxide

[0047] Preparation Example 1

[0048] The preparation method of the cerium-zirconium composite oxide of the present preparation example comprises the following steps:

[0049] Cerium nitrate hexahydrate and zirconyl nitrate were added to deionized water in a molar ratio of 0.8:0.2 to prepare a mixed salt solution with a total concentration of metal cations of 1.0 mol / L. Under stirring, 10% ammonia water was slowly added to adjust the pH to 9.5. After 2h of precipitation reaction at 50℃, the slurry was transferred to a reaction kettle, heated to 120℃, and hydrothermally crystallized for 6h. After centrifugal separation, the slurry was washed with deionized water for 3 times, and vacuum dried at 110℃ until constant weight. Then, the slurry was transferred to a muffle furnace, heated to 500℃ at a heating rate of 5℃ / min, and calcined for 3h. After furnace cooling to room temperature, the cerium-zirconium composite oxide was obtained.

[0050] Preparation Example 2

[0051] The preparation method of the cerium-zirconium composite oxide of the present preparation example comprises the following steps:

[0052] The cerium nitrate hexahydrate and zirconyl nitrate are added into deionized water in a molar ratio of 0.6:0.4, and 5% of the total mass of the cerium nitrate hexahydrate and the zirconyl nitrate is added as Tween 80 to prepare a mixed salt solution with a total concentration of metal cations of 1.0 mol / L, under stirring, 10% ammonia water is slowly added dropwise to adjust the pH to 10.5, and after precipitation reaction at 60℃ for 1.5 h, the slurry is transferred into a reaction kettle, heated to 150℃, and hydrothermally crystallized for 4 h, centrifuged, washed with deionized water for 3 times, vacuum dried at 110℃ to constant weight, transferred into a muffle furnace, heated to 600℃ at a heating rate of 5℃ / min, calcined for 2 h, and cooled to room temperature in the furnace to obtain the cerium-zirconium composite oxide.

[0053] Preparation Example 3

[0054] The preparation method of the cerium-zirconium composite oxide of the present preparation example comprises the following steps:

[0055] The cerium nitrate hexahydrate and zirconyl nitrate are added into deionized water in a molar ratio of 0.6:0.4, and 5% of the total mass of the cerium nitrate hexahydrate and the zirconyl nitrate is added as Tween 80 to prepare a mixed salt solution with a total concentration of metal cations of 1.0 mol / L, under stirring, 10% ammonia water is slowly added dropwise to adjust the pH to 10.5, and after precipitation reaction at 60℃ for 1.5 h, the slurry is transferred into a reaction kettle, heated to 150℃, and hydrothermally crystallized for 4 h, centrifuged, washed with deionized water for 3 times, vacuum dried at 110℃ to constant weight, transferred into a muffle furnace, heated to 600℃ at a heating rate of 5℃ / min, calcined for 2 h, and cooled to room temperature in the furnace to obtain the cerium-zirconium composite oxide.

[0056] Example 1

[0057] The preparation method of the iron-based desulfurizer of the present example comprises the following steps:

[0058] S1: The ferric nitrate nonahydrate, ferrous nitrate, manganese nitrate hexahydrate, and zinc nitrate hexahydrate are mixed in deionized water in a molar ratio of 1.2:1:0.05:0.03 to prepare a mixed salt solution with a total concentration of metal cations of 1.0 mol / L, heated to 35℃, and then 6% low-oxygen air is blown in at a rate of 0.1 L / min, under stirring, 15% ammonia water solution is slowly added dropwise, the dropping rate is controlled to slowly increase the pH of the system to 8.0 within 25 min, the blowing rate of the low-oxygen air is adjusted to 0.3 L / min, and the reaction is continued at this pH for 25 min, and then the reaction slurry is filtered, washed with deionized water, and dried at 90℃ for 1 h, and then ground through a 100-mesh standard sieve to obtain a precursor;

[0059] S2: After the precursor, the composite pore-forming agent, the attapulgite and the cerium-zirconium composite oxide obtained in Preparation Example 1 obtained in S1 were weighed according to a mass ratio of 100:10:10:5, they were placed in a high-speed mixer and mixed for 10 min, then a proper amount of deionized water was sprayed, extrusion molding was performed, and after granulation, they were transferred into a drying oven, dry air was introduced at a flow rate of 0.3 L / min, and programmed temperature rising drying was performed: the temperature was raised to 80 ℃ at a rate of 1 ℃ / min, and then the temperature was raised to 115 ℃ at a rate of 1 ℃ / min, and the temperature was maintained for 1 h, to obtain the iron-based desulfurizer.

[0060] The composite pore-forming agent comprises ammonium bicarbonate and ammonium acetate, and the mass ratio of ammonium bicarbonate to ammonium acetate is 1:1.

[0061] Example 2

[0062] The preparation method of the iron-based desulfurizer of the present example comprises the following steps:

[0063] S1: Iron 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 metal cations of 1.0 mol / L, the solution was heated to 45 ℃, low-oxygen air with an oxygen volume fraction of 5% was introduced at a rate of 0.1 L / min, and under stirring, a 15% ammonia water solution was slowly added dropwise, the dropwise adding rate was controlled to slowly increase the pH of the system to 8.0 within 25 min, the introduction rate of the low-oxygen air was adjusted to 0.3 L / min, and the reaction was continued at this pH for 20 min, the reaction slurry was filtered under pressure, washed with deionized water, dried at 90 ℃ for 1 h, and ground through a 100-mesh standard sieve to obtain a precursor;

[0064] S2: After the precursor, the composite pore-forming agent, the attapulgite and the cerium-zirconium composite oxide obtained in Preparation Example 2 obtained in S1 were weighed according to a mass ratio of 100:20:15:15, they were placed in a high-speed mixer and mixed for 10 min, then a proper amount of deionized water was sprayed, extrusion molding was performed, and after granulation, they were transferred into a drying oven, dry air was introduced at a flow rate of 0.3 L / min, and programmed temperature rising drying was performed: the temperature was raised to 80 ℃ at a rate of 1 ℃ / min, and then the temperature was raised to 115 ℃ at a rate of 1 ℃ / min, and the temperature was maintained for 1 h, to obtain the iron-based desulfurizer.

[0065] The composite pore-forming agent comprises ammonium bicarbonate and ammonium acetate, and the mass ratio of ammonium bicarbonate to ammonium acetate is 1:1.

[0066] Example 3

[0067] The preparation method of the iron-based desulfurizer of the present example comprises the following steps:

[0068] S1: Iron nitrate nonahydrate, ferrous nitrate, manganese nitrate hexahydrate and zinc nitrate hexahydrate were mixed in deionized water in a molar ratio of 1.5:1:0.07:0.04 to prepare a mixed salt solution with a total concentration of metal cations of 1.0 mol / L, and the solution was heated to 40℃. Low-oxygen air with an oxygen volume fraction of 8% was first introduced at a rate of 0.1 L / min, and ammonia water with a mass fraction of 15% was slowly added dropwise under stirring. The dropwise rate was controlled to slowly increase the pH of the system to 8.5 within 25 min. The introduction rate of low-oxygen air was adjusted to 0.3 L / min, and the reaction was continued at this pH for 30 min. The reaction slurry was filtered, washed with deionized water, dried at 90℃ for 1 h, ground to pass through a 100-mesh standard sieve, and the precursor was obtained.

[0069] S2: The precursor obtained in S1, the composite pore-forming agent, the attapulgite and the cerium-zirconium composite oxide obtained in Preparation Example 3 were weighed in a mass ratio of 100:15:12:10, placed in a high-speed mixer, mixed for 10 min, then sprayed with an appropriate amount of deionized water, extruded and molded, cut into particles, and then transferred to a drying oven. Dry air was introduced at a rate of 0.3 L / min for programmed temperature drying: the temperature was increased to 80℃ at a rate of 1℃ / min and maintained for 1 h, then the temperature was increased to 115℃ at a rate of 1℃ / min and maintained for 1 h, and the iron-based desulfurizer was obtained.

[0070] The composite pore-forming agent comprises ammonium bicarbonate and ammonium acetate, and the mass ratio of ammonium bicarbonate to ammonium acetate is 1:1.

[0071] Example 4

[0072] The difference between this example and Example 3 is that:

[0073] Before use, the iron-based desulfurizer also undergoes the following pretreatment steps:

[0074] The iron-based desulfurizer in Example 3 was immersed in an alkaline solution at a solid-liquid ratio of 1 g:5 mL, stirred at a speed of 200 rpm for 3 h, filtered, washed twice with deionized water, and dried at 90℃ for 1 h to obtain the product.

[0075] The alkaline solution comprises ammonia water, ethylenediamine and deionized water, the mass fraction of ammonia water is 10%, and the mass fraction of ethylenediamine is 5%.

[0076] The other steps are the same as in Example 3.

[0077] Example 5

[0078] The difference between this example and Example 3 is that:

[0079] Before use, the iron-based desulfurizer also undergoes the following pretreatment steps:

[0080] The iron-based desulfurizer in Example 3 was immersed in an alkaline solution with a solid-liquid ratio of 1 g:5 mL, mixed at a rotation speed of 200 rpm for 2 h, filtered, washed with deionized water twice, and dried at 90℃ for 1 h to obtain the product.

[0081] The alkaline solution comprises ammonia water, ethylenediamine, triethanolamine and deionized water, the mass fraction of ammonia water is 15%, the mass fraction of ethylenediamine is 5%, and the mass fraction of triethanolamine is 5%.

[0082] The other steps are the same as those in Example 3.

[0083] Example 6

[0084] The difference between this example and Example 3 is that:

[0085] The binder is a modified binder, and the preparation method of the modified binder comprises the following steps:

[0086] Palygorskite, MgCl2, sodium citrate and deionized water were added to the reactor in a mass ratio of 100:10:3:200, mixed at 500 rpm for 1 h, and then the temperature was raised to 55℃ and the mixing was continued for 2 h. After the wet filter cake was obtained by pressure filtration, it was aged at 25℃ for 24 h, transferred into a drying oven, dried at 80℃ to constant weight, ground and then passed through a 200-mesh standard sieve to obtain the modified binder.

[0087] The other steps are the same as those in Example 3.

[0088] Example 7

[0089] The difference between this example and Example 5 is that:

[0090] The binder is a modified binder, and the preparation method of the modified binder comprises the following steps:

[0091] Palygorskite, KCl, sodium tartrate and deionized water were added to the reactor in a mass ratio of 100:15:5:260, mixed at 500 rpm for 1 h, and then the temperature was raised to 65℃ and the mixing was continued for 1.5 h. After the wet filter cake was obtained by pressure filtration, it was aged at 25℃ for 18 h, transferred into a drying oven, dried at 80℃ to constant weight, ground and then passed through a 200-mesh standard sieve to obtain the modified binder.

[0092] The other steps are the same as those in Example 5.

[0093] Comparative Example 1

[0094] The difference between this comparative example and Example 1 is that:

[0095] No cerium-zirconium composite oxide was added;

[0096] The other steps are the same as those in Example 1.

[0097] Comparative Example 2

[0098] The difference between this comparative example and Example 1 is that:

[0099] S1: Iron 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 metal cations of 1.0 mol / L, and the temperature was raised to 35°C. Low-oxygen air with an oxygen volume fraction of 6% was first blown in at a rate of 0.1 L / min, and under stirring, a 15% ammonia water solution was slowly added dropwise. The dropwise rate was controlled to slowly raise the pH of the system to 8.0 within 25 min. The blowing rate of the low-oxygen air was adjusted to 0.3 L / min, and the reaction was continued at this pH for 25 min. The reaction slurry was filtered under pressure, washed with deionized water, dried at 90°C for 1 h, ground through a 100-mesh standard sieve, and the precursor was obtained.

[0100] The rest is the same as in Example 1.

[0101] Comparative Example 3

[0102] The difference between this comparative example and Example 1 is that:

[0103] S1: Iron 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 metal cations of 1.0 mol / L, and the temperature was raised to 35°C. Low-oxygen air with an oxygen volume fraction of 6% was first blown in at a rate of 0.1 L / min, and under stirring, a 15% ammonia water solution was slowly added dropwise. The dropwise rate was controlled to slowly raise the pH of the system to 8.0 within 25 min. The blowing rate of the low-oxygen air was adjusted to 0.3 L / min, and the reaction was continued at this pH for 25 min. The reaction slurry was filtered under pressure, washed with deionized water, dried at 90°C for 1 h, ground through a 100-mesh standard sieve, and the precursor was obtained.

[0104] The rest is the same as in Example 1.

[0105] Comparative Example 4

[0106] The difference between this comparative example and Example 1 is that:

[0107] S1: Iron nitrate nonahydrate and ferrous nitrate were mixed in deionized water in a molar ratio of 1.2:1 to prepare a mixed salt solution with a total concentration of metal cations of 1.0 mol / L, and the solution was heated to 35°C. Low-oxygen air with an oxygen volume fraction of 6% was first introduced at a rate of 0.1 L / min. While stirring, a 15% ammonia water solution was slowly added dropwise, and the dropwise rate was controlled to slowly increase the pH of the system to 8.0 within 25 min. The introduction rate of the low-oxygen air was adjusted to 0.3 L / min, and the reaction was continued at this pH for 25 min. The reaction slurry was filtered under pressure, washed with deionized water, dried at 90°C for 1 h, ground to pass through a 100-mesh standard sieve, and the precursor was obtained;

[0108] Other same as example 1.

[0109] Comparative example 5

[0110] The difference between this comparative example and example 1 is that:

[0111] S2: The precursor obtained in S1, ammonium bicarbonate, attapulgite, and the cerium-zirconium composite oxide obtained in preparation example 1 were weighed in a mass ratio of 100:10:10:5, placed in a high-speed mixer, mixed for 10 min, then sprayed with an appropriate amount of deionized water, extruded into a shape, cut into particles, and then transferred into a drying oven. Dry air was introduced at a rate of 0.3 L / min, and the temperature was programmed to rise as follows: 1°C / min to 80°C, holding for 2 h, then 1°C / min to 115°C, holding for 1 h, to obtain the iron-based desulfurizer.

[0112] Other same as example 1.

[0113] Performance test

[0114] (1) Sample pretreatment: The iron-based desulfurizers prepared in examples 1-7 and comparative examples 1-5 were placed in a forced air drying oven at 80°C for 30 min before testing, then cooled to room temperature in a desiccator and used as needed.

[0115] (2) Specific surface area and pore structure analysis: The specific surface area and pore structure analyzer was used to measure the specific surface area and pore structure at a liquid nitrogen temperature (77K). The sample was vacuum degassed at 50°C for 4 h before testing. The test results are shown in Table 1.

[0116] (3) Mechanical strength determination: The radial crushing force of each particle was measured using a particle strength tester, and the average crushing force was used as an indicator. The test particles were uniformly selected as Ф4mm x 15mm, and the test results are shown in Table 1.

[0117] (4) Desulfurization performance evaluation: Dynamic breakthrough experiments were conducted using a micro fixed bed reactor. The test was divided into two groups:

[0118] Basic performance test: simulated feed gas composition (volume fraction): hydrogen sulfide concentration 100 ppm, water vapor 1%, the rest is nitrogen, space velocity 1000 h -1 ; the test temperature was 80℃, and the breakthrough endpoint was that the H2S concentration at the outlet of the reactor reached 1 ppm twice in succession, and the breakthrough sulfur capacity was calculated, and the test results are shown in Table 1;

[0119] Industrial simulation test: simulate the composition of the raw material gas (volume fraction): hydrogen sulfide concentration is 100 ppm, carbon monoxide is 20%, carbon dioxide is 10%, hydrogen is 2%, water vapor is 1%, the rest is nitrogen, space velocity is 1000h -1 ; the test temperature was 80℃, and the breakthrough endpoint was that the H2S concentration at the outlet of the reactor reached 1 ppm twice in succession, and the breakthrough sulfur capacity was calculated, and the test results are shown in Table 1;

[0120] (5) Regeneration cycle stability test: the desulfurizer that has completed the 80℃ industrial simulation desulfurization test and breakthrough is purged under nitrogen atmosphere for 30 min, and then switched to a regeneration atmosphere (5% by volume of oxygen, 5% by volume of water vapor, and the rest is nitrogen), and the outlet O2 concentration is restored to the inlet level, and no SO2 and other by-products are generated in the outlet gas. Take the breakthrough sulfur capacity of the first cycle as the basis, calculate the sulfur capacity retention rate after the 5th cycle as the evaluation index of regeneration stability, and the test results are shown in Table 1.

[0121] Table 1 Performance test data of iron-based desulfurizers prepared in Examples 1-7 and Comparative Examples 1-5

[0122]

[0123] From the performance test data of the iron-based desulfurizers in Examples 1-3, it can be seen that by adjusting the molar ratio of iron salt to ferrous salt, low-oxygen air and the end point pH of the precipitation reaction, and at the same time cooperating with the synergistic effect of manganese salt and zinc salt in a certain proportion, an iron-based desulfurizer with high specific surface area, suitable pore structure and sufficient mechanical strength can be successfully prepared, which meets the performance requirements of basic desulfurization scenarios.

[0124] Combined with the XRD pattern analysis Figure 1 , it can be seen that under the low-temperature precipitation and drying process, a desulfurizer precursor with hydroxyl iron oxide as the main active phase is successfully prepared, and the characteristic diffraction peaks are mainly located near 26.7° and 35.2°; the secondary peaks at 29.0° and 47.9° correspond to the characteristic crystal faces of Ce 0.8 Zr 0.2 O2 solid solution, and the systematic high-angle shift of the peaks relative to the standard peaks of pure CeO2 indicates that Zr 4+ has successfully embedded into the CeO2 lattice to form a solid solution, which can effectively inhibit grain agglomeration.

[0125] From the performance test data of the iron-based desulfurizer in Examples 1 and Comparative Examples 1-5, it can be seen that the absence of cerium-zirconium composite oxygen storage agent directly leads to a significant decrease 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 the sulfur capacity and regeneration cycle stability are significantly reduced. In addition, the mechanical strength of the desulfurizer without ferrous salt is reduced; the absence of manganese or the simultaneous absence of manganese and zinc results in a simultaneous decrease in desulfurization activity and regeneration cycle stability.

[0126] From the performance test data of the iron-based desulfurizer in Examples 4-7, it can be seen that the alkali solution impregnation treatment can effectively optimize the distribution of active sites on the surface of the desulfurizer, significantly improving its desulfurization capacity in a simulated industrial complex atmosphere; 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, achieving a synergistic improvement in desulfurization performance and cycle stability.

[0127] The specific embodiments are merely an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, and as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for producing an iron-based desulfurizer, characterized by comprising the steps of: The method comprises the following steps: ​ S1: mixing iron salt, ferrous salt, manganese salt and zinc salt in water in a molar ratio of (1.2-2.0):1:(0.05-0.08):(0.03-0.05), heating to 35-45℃, blowing air, adding alkali solution, reacting for 20-30min, and controlling the pH at the end point of the reaction to be 8.0-8.5, solid-liquid separation, washing, drying, and obtaining a precursor; S2: uniformly mixing the precursor, a composite pore-forming agent, a binder and an oxygen storage agent, shaping, drying at 80-115℃, and obtaining an iron-based desulfurizer; The composite pore-forming agent comprises ammonium bicarbonate and ammonium acetate; The volume fraction of oxygen in the air is 5%-8%.

2. The method for producing a ferrous desulfurizer according to claim 1, characterized by, The mass ratio of the precursor, the composite pore-forming agent, the binder and the oxygen storage agent is 100:(10-20):(10-15):(5-15).

3. The method for producing a ferrous desulfurizer according to claim 1, characterized by, The oxygen storage agent is cerium-zirconium composite oxide.

4. The method for producing a ferrous desulfurizer according to claim 3, characterized by, The preparation method of the cerium-zirconium composite oxide comprises the following steps: adding cerium salt and zirconium salt into water in a molar ratio of (0.6-0.8):(0.2-0.4), uniformly mixing, adjusting the pH to 9.5-10.5, performing precipitation reaction at 50-60℃ for 1.5-2h, transferring into a reaction kettle, heating to 120-150℃, hydrothermal crystallization for 4-6h, solid-liquid separation, washing, drying, calcining, cooling, and obtaining cerium-zirconium composite oxide.

5. The method for producing a ferrous desulfurizer according to claim 4, characterized by, After adjusting the pH, 3%-5% of surfactant based on the total mass of the cerium salt and the zirconium salt is further added.

6. The method of producing a ferrous desulfurizer according to claim 1, characterized by, Before use, the iron-based desulfurizer is treated by impregnation with an alkali solution, and the alkali solution comprises ammonia water, organic amine and water.

7. The method of producing a ferrous desulfurizer according to claim 1, characterized by, The binder is attapulgite.

8. The method of producing a ferrous desulfurizer according to claim 1, characterized by, The binder is a modified binder, and the preparation method of the modified binder comprises the following steps: uniformly mixing attapulgite, alkali metal salt or alkaline earth metal salt, organic complexing agent and water, heating to 55-65℃, mixing for 1.5-2h, solid-liquid separation, aging for 18-24h, drying, and crushing to obtain a modified binder.

9. An iron-based desulfurizer prepared by the method according to any one of claims 1-8.

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