Reusable iron oxyhydroxide desulfurizer and preparation method thereof

Abstract

The invention relates to the technical field of desulfurizing agents, in particular to a reusable iron oxyhydroxide desulfurizing agent and a preparation method thereof. The problem that the activity of a traditional material is reduced due to sulfate accumulation and compact layer formation in a vulcanization-regeneration cycle is solved. The preparation method comprises the following steps: dissolving ferric nitrate and urea, adjusting the pH value to 1.8, and adding cerous nitrate and citric acid; heating, introducing zirconium oxynitrate, controlling the pH value at 3.7-3.9 for 2-3 hours, heating to 7.2, adding samarium nitrate and zirconium acetylacetonate, aging, and mixing with bentonite and ammonium bicarbonate for molding; and finally, carrying out segmented activation in a nitrogen and low-oxygen mixed atmosphere. The desulfurizer has high specific surface area and pore volume, the breakthrough sulfur capacity reaches 148-160mgS / g, the 10-time circulating sulfur capacity retention rate is 88-91%, and the desulfurizer is high in particle compressive strength, low in abrasion rate and suitable for the industrial desulfurization process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of desulfurizer, and particularly relates to a reusable hydroxyl ferric oxide desulfurizer and a preparation method thereof. BACKGROUND

[0002] The hydroxyl ferric oxide desulfurizer is widely used in the purification process of natural gas, synthetic gas and other hydrogen sulfide-containing gases. It converts hydrogen sulfide into iron sulfide or ferrous sulfide through chemical adsorption, and is regenerated into active hydroxyl ferric oxide structure in an oxygen-containing atmosphere. However, the traditional hydroxyl ferric oxide material has inherent limitations in the regeneration process: the sulfide product is easy to generate thermodynamically stable sulfate species during oxidation regeneration. Such sulfates are difficult to decompose under low-temperature regeneration conditions, gradually accumulate in the pore and active surface, block the gas diffusion path and cover the active sites, resulting in a continuous decrease in the effective sulfur capacity of the desulfurizer.

[0003] Especially under high-frequency intermittent or continuous regeneration conditions, the hydroxyl ferric oxide lattice repeatedly experiences volume changes during sulfidation-oxidation, which easily causes stress concentration and micro-crack propagation in the particle interior, further aggravating the embedding and retention of sulfates. In addition, excessive local oxygen concentration or temperature fluctuations during the regeneration process promote the formation of a dense sulfide layer, which hinders the diffusion of oxygen to the interior and the migration of sulfide products to the outside, making the regeneration reaction limited to the surface layer, and the deep sulfide cannot be effectively converted, accelerating the overall deactivation of the desulfurizer.

[0004] To improve the regeneration performance, the prior art attempts to improve the redox buffer capacity by doping rare earths (such as cerium) or to enhance the structural stability by modifying with metal oxides such as zirconium and aluminum. However, single-component modification often has difficulty in simultaneously solving multiple challenges such as sulfate accumulation, dense layer inhibition and long-term mass transfer stability: for example, although cerium doping can promote the oxidation of surface sulfides, excessive cerium introduction may cause lattice distortion and reduce the density of iron active sites; and although inorganic zirconium coating can strengthen the skeleton, it may weaken the diffusion efficiency of gas molecules in the pore. Therefore, developing a hydroxyl ferric oxide desulfurizer that can optimize the regeneration performance from nucleation regulation, interface modification to activation path design has become a technical difficulty that needs to be broken through in the field. SUMMARY

[0005] Therefore, the present application aims to provide a reusable hydroxyl ferric oxide desulfurizer and a preparation method thereof, so as to solve the problem that the existing hydroxyl ferric oxide desulfurizer is easy to cause passivation of active sites and significant attenuation of regeneration efficiency due to accumulation of sulfates and formation of a dense sulfide layer in the sulfidation-regeneration cycle, and is difficult to balance high sulfur capacity and long-period cyclic stability.

[0006] In order to achieve the above purpose, the present application provides a preparation method of a reusable hydroxyl ferric oxide desulfurizer, comprising the following steps: (1) Dissolve ferric nitrate nonahydrate and urea in deionized water, add ammonia water solution dropwise to adjust pH to 1.8 to obtain a ferric source-urea solution; then add cerium nitrate hexahydrate solution and citric acid monohydrate solution, and adjust pH to 1.8, and then heat to 85°C and keep constant temperature for 20-40 min; (2) Add zirconyl nitrate dihydrate solution to the system obtained in step (1), heat to 90°C and keep constant temperature, and allow urea to decompose slowly with pH rising; when pH reaches 3.8 for the first time, start timing and control pH at 3.7-3.9 for 2-3 h, and then continue to raise pH to 7.2; at pH 7.2, add samarium nitrate hexahydrate solution, and drop acetylacetone zirconium precursor solution under the condition of maintaining pH at 7.2, and after the dropping is completed, age at 90°C for 4-5 h; cool, filter, wash, dry, crush and sieve to obtain modified hydroxyl iron oxide precursor powder; (3) Mix the modified hydroxyl iron oxide precursor powder with bentonite and ammonium bicarbonate, and knead into shape with water, extrude into strips and dry to obtain shaped particles; (4) Heat the shaped particles to 230°C under nitrogen atmosphere and keep constant temperature for 3 h, then heat to 260°C under oxygen / nitrogen mixed gas atmosphere and keep constant temperature for 2-4 h, and finally cool to room temperature under nitrogen atmosphere to obtain reusable hydroxyl iron oxide desulfurizer.

[0007] Preferably, in step (1), the mass ratio of ferric nitrate nonahydrate, urea, deionized water, cerium nitrate hexahydrate solution and citric acid monohydrate solution is 3600:2200:9000:1200-1260:1080-1120; the mass ratio of cerium nitrate hexahydrate to deionized water in the cerium nitrate hexahydrate solution is 200-260:1000; and the mass ratio of citric acid monohydrate to deionized water in the citric acid monohydrate solution is 280-320:800.

[0008] Preferably, in step (1), the pH adjustment uses ammonia water solution with a mass fraction of 5%.

[0009] Preferably, based on 3600 mass parts of ferric nitrate nonahydrate, the amount of zirconyl nitrate dihydrate solution is 340-360, and the mass ratio of zirconyl nitrate dihydrate to deionized water in the zirconyl nitrate dihydrate solution is 42-60:300; the amount of samarium nitrate hexahydrate solution is 480-500, and the mass ratio of samarium nitrate hexahydrate to deionized water in the samarium nitrate hexahydrate solution is 80-100:400.

[0010] Preferably, based on 3600 mass parts of ferric nitrate nonahydrate, the amount of acetylacetone zirconium precursor solution is 540-560, and the mass ratio of acetylacetone zirconium, ethanol and deionized water in the acetylacetone zirconium precursor solution is 40-60:300:200.

[0011] Preferably, in step (2), when the pH is controlled at 3.7-3.9: when the pH is below 3.7, add a 5% ammonia solution; when the pH is above 3.9, add a 5% nitric acid solution to adjust the pH.

[0012] Preferably, in step (3), the mass ratio of modified iron hydroxyl oxide precursor powder, bentonite, ammonium bicarbonate and deionized water is 950:120-150:180-220:500.

[0013] Preferably, in step (3), the diameter of the extruded strip is 3.5-4.0 mm, the cutting length is 6-8 mm, the drying temperature is 105℃, and the drying time is 8 h.

[0014] Preferably, in step (4), the nitrogen flow rate is 2000 mL / min and the heating rate is 2 °C / min; the oxygen volume fraction in the oxygen / nitrogen mixture is 1 vol%-2 vol%.

[0015] Furthermore, the present invention provides a reusable iron hydroxyl oxide desulfurizer, which is obtained by a method for preparing a reusable iron hydroxyl oxide desulfurizer.

[0016] The beneficial effects of this invention are: This invention utilizes the synergistic effect of cerium doping and citric acid complexation to construct a precursor structure with open channels and high specific surface area during the hydroxyl oxide nucleation stage. This effectively enhances the diffusion rate of hydrogen sulfide molecules within the material and the utilization rate of the reaction interface, significantly improving the initial desulfurization efficiency.

[0017] Introducing zirconium oxynitrate during the weakly acidic nucleation window allows its hydrolysis products to form a stable zirconium-oxygen-iron bond network with the newly formed hydroxyl groups of iron oxyhydroxide. This inhibits the excessive sintering of iron species and the formation of a dense sulfide layer during sulfidation, making the sulfide products more easily contacted and converted by oxygen, thus improving the reversibility of the regeneration reaction.

[0018] The introduction of samarium components couples with the cerium interface, inducing the formation of defect structures rich in oxygen vacancies, enhancing the interfacial oxygen migration rate and redox buffering capacity, reducing the sulfate formation energy barrier, and promoting the efficient conversion of sulfides into elemental sulfur or desorbable sulfur oxides during the regeneration stage, thereby slowing down the passivation of active sites.

[0019] Zirconium acetylacetonate is slowly hydrolyzed in an alkaline environment and directionally deposited on the particle surface as a nano-scale zirconium oxide dispersion phase, forming a porous protective layer and strengthening the bonding strength between particles. This not only protects the internal active phase from airflow erosion but also maintains the structural integrity of the pores during long-term circulation, ensuring mass transfer stability.

[0020] The two-stage activation process removes residual volatile components in an inert atmosphere and then performs mild pre-oxidation in a low-oxygen atmosphere to keep the cerium-samarium interface units in a suitable oxidation state, avoiding lattice sintering or premature sulfate formation caused by high temperature and high oxygen, and pre-setting an efficient conversion path for the subsequent actual regeneration process.

[0021] The synergistic molding strategy of bentonite and ammonium bicarbonate endows the particles with excellent plasticity during the extrusion process. The thermal decomposition of ammonium bicarbonate to create pores and the layer bonding of bentonite work together to form a molded body with both high mechanical strength and well-developed mesoporous structure, which can meet the needs of industrial scenarios such as fixed bed filling and airflow impact. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0023] The bentonite used in this embodiment and comparative example is Sigma-Aldrich product number 285234.

[0024] Example 1: Step S1: Add 9000g of deionized water to the stirred reactor, start mechanical stirring at 400rpm and control the temperature inside the reactor at 25℃, add 3600g of ferric nitrate nonahydrate in batches until completely dissolved, add 2200g of urea again and stir for 30min, then add 5% ammonia solution dropwise to stabilize the pH at 1.8 to obtain an iron source-urea solution; adjust the stirring of the reactor to 450rpm, add a cerium nitrate hexahydrate solution prepared by 1000g of deionized water and 200g of cerium nitrate hexahydrate at 25℃, then add a citric acid monohydrate solution prepared by 800g of deionized water and 280g of citric acid monohydrate, then add 5% ammonia solution dropwise to stabilize the pH at 1.8 again, then raise the temperature to 85℃ at 1℃ / min and stir at a constant temperature for 30min; Step S2: Continue adding a zirconium oxynitrate dihydrate solution prepared from 300g deionized water and 42g zirconium oxynitrate dihydrate to the reactor from Step S1. Then, raise the temperature to 90℃ and maintain this temperature. Utilize the thermal decomposition of urea to slowly raise the pH. Start timing when the pH first reaches 3.8 and maintain the pH between 3.7 and 3.9 for 2 hours. If the pH is below 3.7, add a 5% ammonia solution dropwise; if the pH is above 3.9, add a 5% nitric acid solution dropwise to correct it. After completion, continue stirring at 90℃ and 450rpm, allowing the pH to rise naturally to 7.2. If the pH is above 7.3, add a 5% nitric acid solution dropwise to correct it. Then, add 40g of urea solution to the reactor. A samarium hexahydrate solution was prepared by mixing 0g of deionized water with 80g of samarium hexahydrate and stirring for 30min. Then, 40g of zirconium acetylacetonate was added to a mixed solvent of 300g of ethanol and 200g of deionized water and stirred at 60℃ to form a homogeneous precursor solution. This precursor solution was then added dropwise to the reactor over 40min, while simultaneously adding a 5% (w / w) ammonia solution to maintain the pH at 7.2. After the addition was completed, the reactor was aged at 90℃ for 4h (with reflux during this period). The reactor was then allowed to cool naturally to 40℃ and heating was stopped. The mixture was filtered to obtain a wet filter cake, which was then washed three times with deionized water and once with ethanol. After drying at 110℃ for 12h, the cake was pulverized and passed through a 60-mesh sieve to obtain the modified iron hydroxyl oxide precursor powder. Step S3: Add 950g of modified iron hydroxyl oxide precursor powder, 120g of bentonite, and 180g of ammonium bicarbonate to the kneader in sequence and dry mix for 5 minutes. Then add 500g of deionized water and wet mix for 15 minutes to form an extrudable plastic mud. After sealing and standing for 60 minutes, the mud is extruded into strips with a diameter of 3.5mm and cut into 6mm lengths. Finally, dry at 105℃ for 8 hours to obtain shaped granules. Step S4: Take the shaped granules and load them into the tube furnace reaction tube. Introduce nitrogen and set the flow rate to 2000 mL / min. Heat the gas to 230°C at 2°C / min and hold it at that temperature for 3 hours. Then, switch to a mixed gas (2 vol% oxygen + 98 vol% nitrogen) at a total flow rate of 2000 mL / min and heat the gas to 260°C and hold it at that temperature for 2 hours. After that, switch back to nitrogen and allow it to cool naturally to room temperature to obtain a reusable hydroxyl iron oxide desulfurizing agent.

[0025] Example 2: The difference from Example 1 is as follows: in step S1, the amount of cerium nitrate hexahydrate was adjusted from 200g to 260g, and the amount of citric acid monohydrate was adjusted from 280g to 320g; in step S2, the amount of zirconium oxynitrate dihydrate was adjusted from 42g to 55g, samarium nitrate hexahydrate was adjusted from 80g to 100g, and zirconium acetylacetonate was adjusted from 40g to 60g; after the addition, the aging time at 90°C was adjusted from 4h to 5h; the other conditions are the same as in Example 1.

[0026] Example 3: The difference from Example 1 is as follows: in step S1, the amount of cerium nitrate hexahydrate was adjusted from 200g to 240g, and the amount of citric acid monohydrate was adjusted from 280g to 300g; in step S2, the amount of zirconium oxynitrate dihydrate was adjusted from 42g to 60g, and the pH was controlled at 3.7-3.9 for 2 hours was adjusted to be controlled at 3.7-3.9 for 3 hours, the amount of samarium nitrate hexahydrate was adjusted from 80g to 90g, the amount of zirconium acetylacetonate was adjusted from 40g to 50g, and the aging time at 90°C after the addition was adjusted from 4 hours to 5 hours; the other conditions are the same as in Example 1.

[0027] Example 4: The difference from Example 1 is that: in step S2, the amount of zirconium acetylacetonate was adjusted from 40g to 60g, and the addition to the reactor was changed from 40min to 60min; in step S3, the amount of ammonium bicarbonate was adjusted from 180g to 220g; the other conditions were the same as in Example 1.

[0028] Comparative Example 1: The difference from Example 1 is that in step S1, the cerium nitrate hexahydrate solution prepared by 1000g of deionized water and 200g of cerium nitrate hexahydrate is not added, and the other conditions are the same as in Example 1.

[0029] Comparative Example 2: The difference from Example 1 is that the citric acid monohydrate solution prepared by 800g of deionized water and 280g of citric acid monohydrate is not added in step S1, and the other conditions are the same as in Example 1.

[0030] Comparative Example 3: The difference from Example 1 is that in step S2, the zirconium oxynitrate dihydrate solution prepared by 300g of deionized water and 42g of zirconium oxynitrate dihydrate is not added immediately after step S1. Instead, the zirconium oxynitrate dihydrate solution is added after the pH naturally rises to 7.2 and stabilizes. Then, a 5% (w / w) ammonia solution is added dropwise to maintain the pH at 7.2 before continuing the subsequent steps. The other conditions are the same as in Example 1.

[0031] Comparative Example 4: The difference from Example 1 is that in step S2, the samarium hexahydrate solution prepared by 400g of deionized water and 80g of samarium hexahydrate is not added, and the other conditions are the same as in Example 1.

[0032] Comparative Example 5: The difference from Example 1 is that zirconium acetylacetonate and its precursor solution are not added in step S2, and the corresponding dropwise addition operation is not performed. The other conditions are the same as in Example 1.

[0033] Comparative Example 6: The difference from Example 1 is that in step S4, after heating to 230°C and holding the temperature for 3 hours under a nitrogen atmosphere, the mixture is not switched to a mixed gas. Instead, nitrogen is continued to be introduced at a total flow rate of 2000 mL / min and the temperature is raised to 260°C and held for 2 hours. The other conditions are the same as in Example 1.

[0034] Performance testing: Specific surface area and pore structure: Specific surface area and pore structure were determined according to GB / T 19587-2017. After grinding each sample, 0.30 g was weighed and placed in a sample tube. The sample was degassed under vacuum at 200℃ for 6 h. Nitrogen adsorption was used, and the measurement temperature was 77 K. The relative pressure P / P0 range was 0.05-0.30 for BET fitting. The total pore volume was calculated using the BJH method.

[0035] Breakthrough sulfur capacity: A fixed-bed breakthrough evaluation device was constructed according to HG / T 4354-2012, with a packing volume of 50.0 g, a bed inner diameter of 25 mm, a bed height of 100 mm, a test temperature of 30℃, a total inlet flow rate of 1000 mL / min, and an inlet gas composition of 0.20 vol% hydrogen sulfide, 1.0 vol% oxygen, and the remainder nitrogen, with an inlet pressure of 0.10 MPa. An online hydrogen sulfide analyzer was used to continuously monitor the outlet hydrogen sulfide volume fraction, with a sampling period of 10 s. The breakthrough point was defined as when the outlet hydrogen sulfide volume fraction reached 0.02 vol%. When the breakthrough point was reached, the gas intake was stopped and the breakthrough time was recorded. The (inlet hydrogen sulfide volume fraction - outlet hydrogen sulfide volume fraction) was converted into the molar amount of hydrogen sulfide removed per unit time according to the ideal gas law, multiplied by the sulfur molar mass of 32.06 g / mol, integrated over time, and finally divided by the sample mass to obtain the breakthrough sulfur capacity (mgS / g).

[0036] Cyclic regeneration performance: Cyclic regeneration was evaluated on a fixed-bed device. The sulfidation stage conditions were consistent with the breakthrough sulfur capacity test, and the breakthrough endpoint for each cycle was defined as the outlet hydrogen sulfide volume fraction reaching 0.02 vol%. In the regeneration stage of each cycle, a mixed gas (2 vol% oxygen + 98 vol% nitrogen) was used with a total flow rate of 1000 mL / min and a heating rate of 2℃ / min to 260℃, which was then held at the temperature for 2 hours. The gas flow rate was then switched to nitrogen at 1000 mL / min and allowed to cool naturally to room temperature before starting the next cycle. Ten cycles were performed consecutively, and the breakthrough sulfur capacity for the first and tenth cycles was calculated. The sulfur capacity retention rate (%) was calculated as the ratio of the breakthrough sulfur capacity of the tenth cycle to the breakthrough sulfur capacity of the first cycle × 100%.

[0037] Particle compressive strength and abrasion rate: The particle compressive strength was tested according to GB / T 44750-2024. Thirty whole particles from each sample were taken and crushed using a crushing force tester at a loading speed of 1 mm / min. The crushing force of each particle was recorded and the arithmetic mean was taken as the compressive strength (N / particle). The abrasion rate was tested according to HG / T 2976-2011. 50.0 g of the sample dried at 105℃ for 2 h was weighed and placed in the grinding cylinder of the abrasion tester. The inner diameter of the grinding cylinder was 120 mm, the length was 150 mm, and there was one inner baffle (length 150 mm, height 18 mm). The rotation speed was 60 r / min and the rotation time was 30 min. After the test, the sample was taken out and the mass of fine powder produced by abrasion was weighed according to the standard sieve. The abrasion rate (%) was calculated.

[0038] Table 1 Performance Test Results

[0039] Data Analysis: As can be seen from the data in Table 1, the reusable ferric hydroxide desulfurizer prepared by this invention maintains a high level in terms of specific surface area and total pore volume. The sulfur penetration capacity shows an increasing trend with the synergistic introduction of cerium nitrate hexahydrate, citric acid monohydrate, zirconium oxynitrate dihydrate, and samarium nitrate hexahydrate. Furthermore, it maintains a high sulfur capacity retention rate after recycling. This may be because: citric acid monohydrate has a complexing effect on the ferric nitrate nonahydrate and urea system under acidic conditions, promoting a finer formation of the generated ferric hydroxide precursor and the formation of a more developed pore structure; zirconium oxynitrate dihydrate participates in hydrolysis and deposition in the weakly acidic region, which is beneficial for constructing a more stable inorganic structure and reducing the clogging of pores by sulfurization products; and the addition of zirconium acetylacetonate and samarium nitrate hexahydrate in the alkaline stage further regulates the chemical environment of the particle surface, making it easier for the formed particles to recover their active centers when in contact with oxygen during the regeneration stage. At the same time, the pore-forming effect of ammonium bicarbonate and the toughening effect of bentonite work together to enable the material to achieve high reaction efficiency while maintaining low wear and good particle compressive strength, making it suitable for long-term operation in fixed beds.

[0040] As can be seen from the data in Table 1 for Example 1 and Comparative Example 1, without the addition of cerium nitrate hexahydrate, the breakthrough sulfur capacity and circulating sulfur capacity retention rate of the samples both decreased significantly, while the changes in specific surface area and total pore volume were relatively limited. The main reason for this may be that the cerium component introduced by cerium nitrate hexahydrate can participate in the redox conversion process during desulfurization and regeneration, promoting faster reaction of hydrogen sulfide under oxygen-containing conditions and inhibiting the deep accumulation of sulfides in the pores. When this component is missing, even with the pore-forming effect of citric acid monohydrate and the structural stabilizing effect of zirconium and samarium components, the reaction process is more easily limited by the active centers being covered by sulfide products, leading to a decrease in effective utilization and regeneration reversibility.

[0041] As can be seen from the data in Table 1 for Example 1 and Comparative Example 2, without the addition of citric acid monohydrate, the specific surface area and total pore volume are significantly reduced, and the sulfur penetration capacity decreases accordingly. However, the compressive strength of the particles increases and the wear rate decreases. The main reason for this may be that citric acid monohydrate plays a role in complexing, slow-release, and nucleation regulation of the ferric nitrate nonahydrate system in step S1. Combined with ammonium bicarbonate, it can form a more open pore structure, thereby improving the usable interface for gas diffusion and sulfidation reaction. Without citric acid monohydrate, the particles are denser, and although the mechanical properties are better, the reaction and mass transfer are limited, making it difficult to fully realize the desulfurization efficiency.

[0042] As can be seen from the data in Table 1 for Example 1 and Comparative Example 3, when zirconium oxynitrate dihydrate was not added immediately after step S1 in step S2, but instead added after the system became alkaline, the specific surface area, total pore volume, and sulfur penetration capacity all decreased, and the wear rate increased. The main reason for this may be that if zirconium oxynitrate dihydrate participates in hydrolysis and deposition in a weakly acidic region, it is more likely to co-grow with the iron hydroxide precursor, forming a more uniform zirconium-modified layer and providing support for the pore walls; however, under alkaline conditions, the addition of hydroxides that readily generate zirconium and cause local agglomeration leads to pore blockage and uneven component distribution, thereby weakening the stability of the containment and diffusion channels for sulfide products.

[0043] As can be seen from the data in Table 1 for Examples 1, 4, and 5, the cyclic sulfur capacity retention rate of the samples decreased when either samarium nitrate hexahydrate or zirconium acetylacetonate was missing. Comparative Example 5 also showed a trend of decreased particle compressive strength and increased wear rate. The main reason for this may be that the samarium component introduced by samarium nitrate hexahydrate can regulate the interaction between the iron hydroxyl oxide surface and the zirconium component, making it easier to restore reactivity in the presence of oxygen during the regeneration stage. Meanwhile, zirconium acetylacetonate slowly releases the zirconium source during the alkaline stage, which is beneficial for forming a more continuous zirconium-modified phase on the particle surface and improving the structural integrity of the formed particles. When either is missing, interfacial stability and regeneration reversibility are weakened, making the pore structure decay and active center shielding during the cycling process more pronounced.

[0044] As can be seen from the data in Table 1 for Example 1 and Comparative Example 6, when step S4 involves heating and activation only under a nitrogen atmosphere without switching to an oxygen-containing mixed gas, the breakthrough sulfur capacity and cyclic sulfur capacity retention rate of the samples both decrease significantly, but the specific surface area, total pore volume, and particle mechanical properties do not change much. The main reason for this may be that the oxygen-containing activation process can complete the surface state reforming of iron hydroxyl oxide and cerium, zirconium, and samarium components under relatively mild conditions, making it easier for initial active centers to form and maintain reversibility in the subsequent regeneration stage. Without this activation step, even if an oxygen-containing gas is introduced during the regeneration stage, the recoverability of the active centers inside the material is still limited, leading to accelerated cycle decay.

[0045] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for preparing a reusable ferric oxyhydroxide desulfurizer, characterized by, The method comprises the following steps: (1) dissolving ferric nitrate nonahydrate and urea in deionized water, adding ammonia water solution dropwise to adjust pH to 1.8 to obtain an iron source-urea solution; then adding cerium nitrate hexahydrate solution and citric acid monohydrate solution, adjusting pH to 1.8, and then heating to 85℃ and constant temperature stirring for 20-40 min; (2) adding zirconyl nitrate dihydrate solution to the system obtained in step (1), heating to 90℃ and constant temperature, allowing urea to decompose slowly as pH increases; when pH reaches 3.8 for the first time, start timing and control pH at 3.7-3.9 for 2-3 h, then continue to increase pH to 7.2; adding samarium nitrate hexahydrate solution at pH 7.2, and adding zirconium acetylacetone precursor solution dropwise under the condition of maintaining pH at 7.2, aging for 4-5 h at 90℃ after the end of dropwise adding; cooling, filtering, washing, drying, crushing and sieving to obtain modified hydroxyl iron oxide precursor powder; (3) mixing the modified hydroxyl iron oxide precursor powder with bentonite and ammonium bicarbonate, and kneading and shaping with water, then extruding and drying to obtain shaped particles; (4) heating the shaped particles to 230℃ and constant temperature for 3 h under nitrogen atmosphere, then heating to 260℃ and constant temperature for 2-4 h under oxygen / nitrogen mixed gas atmosphere, and finally cooling to room temperature under nitrogen atmosphere to obtain reusable hydroxyl iron oxide desulfurizer.

2. The method of claim 1, wherein the method is characterized by, In step (1), the mass ratio of ferric nitrate nonahydrate, urea, deionized water, cerium nitrate hexahydrate solution and citric acid monohydrate solution is 3600:2200:9000:1200-1260:1080-1120; the mass ratio of cerium nitrate hexahydrate to deionized water in the cerium nitrate hexahydrate solution is 200-260:1000; the mass ratio of citric acid monohydrate to deionized water in the citric acid monohydrate solution is 280-320:

800.

3. The method of claim 1, wherein the method is characterized by: In step (1), the pH adjustment uses ammonia water solution with a mass fraction of 5%.

4. The method of claim 1, wherein the method is characterized by: Taking 3600 mass parts of ferric nitrate nonahydrate as the basis, the amount of zirconyl nitrate dihydrate solution is 340-360, and the mass ratio of zirconyl nitrate dihydrate to deionized water in the zirconyl nitrate dihydrate solution is 42-60:300; the amount of samarium nitrate hexahydrate solution is 480-500, and the mass ratio of samarium nitrate hexahydrate to deionized water in the samarium nitrate hexahydrate solution is 80-100:

400.

5. The method of claim 1, wherein the method is characterized by: Taking 3600 mass parts of ferric nitrate nonahydrate as the basis, the amount of zirconium acetylacetone precursor solution is 540-560 mass parts, and the mass ratio of zirconium acetylacetone, ethanol and deionized water in the zirconium acetylacetone precursor solution is 40-60:300:

200.

6. The method of claim 1, wherein the method is characterized by: In step (2), when pH is controlled at 3.7-3.9: when pH is lower than 3.7, ammonia water solution with a mass fraction of 5% is added dropwise, and when pH is higher than 3.9, nitric acid solution with a mass fraction of 5% is added dropwise to adjust.

7. The method of claim 1, wherein the method is characterized by: In step (3), the mass ratio of modified hydroxyl iron oxide precursor powder, bentonite, ammonium bicarbonate and deionized water is 950:120-150:180-220:

500.

8. The method of claim 1, wherein the method is characterized by: The extruded strip in step (3) has a diameter of 3.5-4.0 mm, a cutting length of 6-8 mm, and a drying temperature of 105°C and a drying time of 8 h.

9. The method of claim 1, wherein the method is characterized by: In step (4), the nitrogen flow rate is 2000 mL / min, the temperature increasing rate is 2°C / min, and the oxygen / nitrogen mixed gas has an oxygen volume fraction of 1 vol%-2 vol%.

10. A reusable ferric oxyhydroxide desulfurizer characterized by, The method for preparing the reusable ferric oxyhydroxide desulfurizer according to any one of claims 1-9.

Images