Solid desulfurizer, preparation method and application thereof

Abstract

The application provides a solid desulfurizer, a preparation method and application, and belongs to the technical field of desulfurizers. The application is prepared by taking iron ions and manganese ions as a bimetallic center, complexing with a benzoic acid organic ligand, adding alpha-cyclodextrin to build a binary metal organic framework, and calcining under a protective atmosphere. The bimetallic molar ratio is 1-15:1, the total amount of the bimetallic and the alpha-cyclodextrin molar ratio is 1:0.1-0.5, and the ligand and the iron ion molar ratio is 2-4:1. The desulfurizer realizes deep removal of hydrogen sulfide by means of the synergistic effect of physical adsorption, chemical adsorption and catalytic oxidation, the sulfur capacity reaches 5.3-6.9 mmol / g, and the desulfurizer can be regenerated by blowing hot inert gas at 160-200 DEG C, the retention rate is more than 84% after three times of regeneration, and the desulfurizer is suitable for desulfurization of industrial gases such as natural gas and biogas, and has the advantages of high efficiency, stability and environmental protection.

Description

Technical Field

[0001] This invention relates to the field of desulfurizing agent technology, and in particular to a solid desulfurizing agent, its preparation method, and its application. Background Technology

[0002] In industrial sectors such as natural gas and biogas, hydrogen sulfide (H2S) poses a significant hazard, corroding equipment, poisoning catalysts, and polluting the environment, making its removal an urgent necessity.

[0003] Current mainstream wet desulfurization equipment is complex and energy-intensive, while dry desulfurization lacks precision, is difficult to regenerate, and is prone to secondary pollution. Although single metal-organic frameworks are used for desulfurization, they suffer from poor stability, limited adsorption capacity, low selectivity, and poor regeneration performance. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a solid desulfurizing agent. Using iron and manganese ions as bimetallic centers, it complexes with benzoic acid-based organic ligands to construct a synergistic binary metal-organic framework. Precise addition of α-cyclodextrin achieves uniform bimetallic dispersion, inhibits metal ion hydrolysis, and preserves adsorption micropores. Further calcination in a tubular furnace under a protective atmosphere enhances framework stability and the formation of the MnFe2O4 spinel active structure. Through the synergistic effects of physical adsorption, chemical adsorption, and catalytic oxidation, deep removal of hydrogen sulfide is achieved. After adsorption saturation, it can be efficiently regenerated by purging with a thermal inert gas. This agent combines high sulfur capacity, high stability, and environmental friendliness and economy, effectively overcoming the pain points of existing wet desulfurization equipment (complexity, high energy consumption) and dry desulfurization (insufficient precision, difficult regeneration).

[0005] One objective of this invention is to provide a method for preparing a solid desulfurizing agent, comprising the following steps:

[0006] Benzoic acid-based organic ligands were dissolved in an organic solvent to obtain solution 1;

[0007] Iron salt, manganese salt and α-cyclodextrin were dissolved in water to obtain solution 2;

[0008] Solution 2 was added to solution 1, and after mixing and reacting, the mixture was centrifuged, washed, and dried to obtain precursor M.

[0009] The precursor M was calcined under a protective atmosphere to obtain a solid desulfurizing agent.

[0010] Preferably, the benzoic acid-based organic ligand includes one or more of isophthalic acid, phthalic acid, terephthalic acid, or 5-hydroxyisophthalic acid.

[0011] Preferably, the molar ratio of iron ions in the iron salt to manganese ions in the manganese salt is (1-15):1.

[0012] Preferably, the molar ratio of the benzoic acid-based organic ligand to the iron ion is (2-4):1.

[0013] Preferably, the molar ratio of the sum of the iron ions in the iron salt and the manganese ions in the manganese salt to the molar ratio of the α-cyclodextrin is 1:(0.1–0.5:).

[0014] Preferably, the iron salt includes ferric chloride hexahydrate, ferric nitrate nonahydrate, ferric sulfate nonahydrate, or anhydrous ferric chloride;

[0015] The manganese salts include manganese chloride tetrahydrate, manganese nitrate hexahydrate, manganese sulfate monohydrate, or anhydrous manganese chloride.

[0016] Preferably, the calcination is carried out in a tube furnace for 1.5-3 hours.

[0017] Preferably, the organic solvent includes N,N One or more of dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, or methanol.

[0018] The second objective of this invention is to provide a solid desulfurizing agent prepared by the preparation method described above.

[0019] The third objective of this invention is to provide an application of the solid desulfurizing agent as described above, wherein the desulfurizing agent is used to remove hydrogen sulfide from industrial gases;

[0020] The industrial gas is selected from at least one of natural gas, biogas, refinery gas, chemical synthesis gas, and coal-fired flue gas.

[0021] Preferably, after the solid desulfurizer is saturated with adsorption, it is regenerated by purging with a thermal inert gas; the conditions for purging with the thermal inert gas are: temperature 160-200℃, time 3-5h, and the thermal inert gas is high-purity nitrogen.

[0022] The beneficial effects of this invention are:

[0023] This invention uses Fe 3+ -Mn 2+ A synergistic system is constructed with bimetals as the core, Fe 3+ Establishing a stable binary metal-organic framework provides solid structural support for desulfurization. 2+It exhibits highly efficient catalytic oxidation activity, converting adsorbed hydrogen sulfide into elemental sulfur, overcoming the capacity limitations of single physical adsorption. Combined with the complexing and dispersing effect of α-cyclodextrin, the bimetallic compounds are uniformly distributed within the framework, preventing agglomeration and obscuring of active sites. Simultaneously, α-cyclodextrin inhibits metal ion hydrolysis, reducing amorphous hydroxide impurities and ensuring precursor purity. Ultimately, the desulfurizer achieves a sulfur capacity of 5.3-6.9 mmol / g, with a sulfur capacity retention rate maintained at 84%-88% after three regenerations, significantly superior to single-metal systems or traditional desulfurizers.

[0024] The tubular furnace calcination process ensures the formation of an effective active structure in the desulfurizer. The protective atmosphere prevents metal ion oxidation, and the high-temperature environment strengthens the coordination bonds between ligands and metal ions, constructing a robust three-dimensional framework. This framework supports the micropores left after the thermal decomposition of α-cyclodextrin and enhances the hydrothermal stability and mechanical strength of the desulfurizer, making it resistant to the moisture environment of industrial gases. The micropores formed after the decomposition of α-cyclodextrin complement the pores of the binary framework, constructing a multi-level pore structure. This increases adsorption sites and ensures smooth mass transfer, preventing framework collapse or loss of active sites during use and extending the service life of the desulfurizer.

[0025] This invention's desulfurizing agent is in solid form, requiring no complex supporting equipment, simplifying operation, and requiring minimal space, thus reducing industrial application costs. Compared to the drawbacks of traditional dry desulfurization methods, such as difficult regeneration and the potential for secondary pollution, this desulfurizing agent can be regenerated through purging with a 160-200℃ hot inert gas. The regeneration conditions are mild, energy consumption is low, and no harmful waste is generated during the regeneration process, meeting environmental protection requirements. The specific structure of the binary metal-organic framework, combined with the micropores reserved by α-cyclodextrin, gives the desulfurizing agent a highly selective adsorption capacity for hydrogen sulfide in industrial gases. It can precisely remove hydrogen sulfide from various industrial gases, including natural gas, biogas, and refinery gas, without affecting other effective components in the gas. During the desulfurization process, physical adsorption, chemical adsorption, and catalytic oxidation occur synergistically, achieving deep removal of hydrogen sulfide. This meets the stringent requirements of industrial production for gas purification, effectively avoiding problems such as hydrogen sulfide corrosion of equipment and catalyst poisoning, ensuring the safe and stable operation of industrial production. Attached Figure Description

[0026] Figure 1 The image is a scanning electron microscope (SEM) analysis image of Example 2;

[0027] Figure 2 The images show the X-ray diffraction patterns of Example 2 and Comparative Example 1. Detailed Implementation

[0028] The present application will now be described in further detail with reference to embodiments. In the following description, certain specific details are included to provide a comprehensive understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments can be implemented without employing one or more of these specific details, but using other methods, components, materials, etc. Unless otherwise required by the present invention, the terms "comprising" and "including" should be interpreted in an open-ended, inclusive sense, meaning "including but not limited to". Throughout this specification, "an embodiment," "an embodiment," "a preferred embodiment," or "some embodiments" means that at least one embodiment includes a specific reference element, structure, or feature related to that embodiment. Therefore, the phrases "in an embodiment," "in an embodiment," "in a preferred embodiment," or "in some embodiments" appearing in different places throughout the specification do not necessarily all refer to the same embodiment. Furthermore, specific elements, structures, or features may be combined in one or more embodiments in any suitable manner.

[0029] According to a first aspect of the present invention, a method for preparing a solid desulfurizing agent is provided, comprising the following steps:

[0030] Benzoic acid-based organic ligands were dissolved in an organic solvent to obtain solution 1;

[0031] Iron salt, manganese salt and α-cyclodextrin were dissolved in water to obtain solution 2;

[0032] Solution 2 was added to solution 1, and after mixing and reacting, the mixture was centrifuged, washed, and dried to obtain precursor M.

[0033] The precursor M was calcined under a protective atmosphere to obtain a solid desulfurizing agent.

[0034] In this invention, solution 1 is prepared by dissolving benzoic acid-based organic ligands in an organic solvent because benzoic acid-based organic ligands contain multiple carboxyl groups and require complete dissolution to efficiently coordinate with metal ions. Benzoic acid-based organic ligands exhibit good solubility in organic solvents such as N,N-dimethylformamide and dimethyl sulfoxide, avoiding the problem of uneven dissolution caused by direct mixing with aqueous metal salt solutions. Pre-dissolving the ligands also creates a uniform environment for subsequent coordination reactions with metal ions, ensuring the uniformity of the binary metal-organic framework structure and laying the foundation for the stable performance of the desulfurizer.

[0035] Solution 2 was prepared by dissolving iron and manganese salts in water and adding α-cyclodextrin. The core principle is to utilize the unique structure and function of α-cyclodextrin. Iron and manganese salts are readily soluble in water, forming a homogeneous aqueous solution of metal ions. α-cyclodextrin can form complexes with iron and manganese ions, reducing the concentration of free metal ions and preventing metal aggregation due to rapid coordination at excessively high local concentrations during subsequent mixing. This improves the uniformity of bimetallic distribution within the framework. Simultaneously, the complexing effect of α-cyclodextrin can also inhibit Fe... 3+ / Mn 2+ Hydrolysis reduces the formation of impurities such as amorphous hydroxides, ensuring the purity of the precursor.

[0036] Solution 2 is added to solution 1, followed by mixing, centrifugation, washing, and drying to obtain precursor M. This is because the mixing process allows the ligands to fully contact the metal ions and undergo coordination reactions, forming a binary metal-organic framework precursor. Centrifugation quickly separates the solid products generated during the reaction, washing removes unreacted ligands, metal salts, and other impurities, and drying removes moisture and residual solvents from the product, preventing these impurities from affecting the structure and activity of the desulfurizer during subsequent calcination and ensuring the purity and integrity of precursor M.

[0037] The precursor M is calcined under a protective atmosphere to obtain a solid desulfurizer because calcination promotes the decomposition of organic ligands in the precursor, forming a stable binary metal-organic framework structure. The protective atmosphere prevents the precursor from being oxidized at high temperatures, avoiding changes in the valence state of metal ions that could affect desulfurization activity. Simultaneously, α-cyclodextrin decomposes into small molecules such as CO2 and H2O during calcination, leaving no residual impurities and leaving micropores in the desulfurizer that match its own cavity size, increasing adsorption sites and enhancing the adsorption capacity for sulfides. Appropriate calcination conditions also allow for sufficient coordination of metal ions, further improving the structural stability and catalytic activity of the desulfurizer, ensuring it possesses both high sulfur capacity and renewability.

[0038] In a preferred embodiment of the present invention, the molar ratio of iron ions in the iron salt to manganese ions in the manganese salt is (1-15):1.

[0039] In this invention, the (1-15):1 ratio allows the framework-building function of iron ions and the catalytic oxidation function of manganese ions to complement each other, while α-cyclodextrin further enhances this synergistic effect. In aqueous solution, α-cyclodextrin forms complexes with iron and manganese ions, significantly reducing the concentration of free metal ions and preventing aggregation due to rapid coordination caused by excessively high local concentrations. Within this ratio range, iron ions can fully construct a complete framework, and manganese ions can ensure a sufficient number of catalytic sites. α-cyclodextrin, by slowly releasing metal ions, ensures uniform coordination between the two metals and the ligands, greatly improving the uniformity of the bimetallic distribution in the MOF precursor and preventing the aggregation of a certain metal that might obscure active sites due to improper ratios. Simultaneously, the complexing effect of α-cyclodextrin can also inhibit Fe... 3+ / Mn 2+ The hydrolysis of iron ions and the (1-15):1 ratio can reduce the hydrolysis tendency of metal ions. The synergy of the two can minimize the formation of amorphous Fe(OH)3, Mn(OH)2 and other impurities, ensuring the purity of the precursor. This ratio range complements the micropore regulation effect of α-cyclodextrin. After thermal decomposition, α-cyclodextrin leaves micropores that match its own cavity, providing sufficient sites for sulfide adsorption. However, the effectiveness of the micropores depends on the integrity of the framework structure. When iron ions and manganese ions are in a (1-15):1 ratio, the framework structure is stable, the micropores left by α-cyclodextrin can be completely preserved, and the uniformly dispersed iron ion coordination sites and manganese ion catalytic sites can form an adsorption-catalytic synergy with the micropores. After the micropores adsorb H2S, it is quickly transferred to the adjacent active sites. Manganese ions catalyze its oxidation to elemental sulfur, while iron ions are fixed through chemical adsorption, which greatly improves the sulfur capacity. If the ratio deviates from this range, the framework collapse will lead to micropore failure, or insufficient catalytic sites will prevent the efficient conversion of H2S adsorbed by the micropores. Even if α-cyclodextrin can provide micropores, it will be difficult to improve the desulfurization efficiency.

[0040] The molar ratio of (1-15):1 is the optimal balance range between the iron ion framework construction and the manganese ion catalytic activity. α-Cyclodextrin solves the problems of agglomeration and impurity generation that may occur in bimetals within this ratio range by complexing dispersion, inhibiting hydrolysis, and reserving micropores. This maximizes the synergistic effect of bimetals and ultimately achieves the core goals of stable desulfurizer structure, high sulfur capacity, and renewability.

[0041] In this invention, the molar ratio of iron ions to manganese ions is, for example, 15:1, 14:1, 13:1, 12:1, 11:1, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1 or 1:1.

[0042] In a preferred embodiment of the present invention, the molar ratio of iron ions to manganese ions is 4:1.

[0043] In a preferred embodiment of the present invention, the molar ratio of the benzoic acid-based organic ligand to the iron ion is (2-4):1.

[0044] In this invention, the common coordination number of iron ions is 6, while benzoic acid-based organic ligands are bidentate ligands, each providing two coordination sites. The molar ratio of (2-4):1 allows the ligands to provide exactly 4-8 coordination sites, which can basically meet the coordination requirements of iron ions, ensuring that iron ions and ligands form stable coordination bonds to construct a three-dimensional framework, while reserving some coordination sites for binding with manganese ions, creating conditions for the uniform dispersion of the bimetallic compound within the framework, and avoiding the aggregation of a single metal due to insufficient coordination, thus avoiding waste of active sites.

[0045] This ratio effectively avoids structural defects caused by insufficient or excessive ligands. If the molar ratio of ligand to iron ions is less than 2:1, insufficient ligands will lead to unsaturated coordination of iron ions, easily forming easily aggregated intermediates, damaging the integrity of the binary metal-organic framework, and increasing the risk of metal ion loss, thus reducing the hydrothermal stability and service life of the desulfurizer. If the molar ratio is greater than 4:1, excessive ligands cannot fully participate in coordination and will exist in a free state. Before subsequent calcination, they may block the framework channels or form unstable complexes with iron ions, which can easily lead to the collapse of the framework during calcination and affect the structural stability of the desulfurizer.

[0046] A ratio of (2-4):1 achieves a balance between physical adsorption and catalytic activity. The rigid benzene ring structure of benzoic acid-based organic ligands can regulate the pore size and specific surface area of ​​the metal-organic framework. At this ratio, the framework exhibits well-developed pores and a sufficient specific surface area, providing ample physical adsorption sites for H2S and a smooth mass transfer channel for the catalytic reaction. Furthermore, a proper ratio of ligand to iron ions ensures uniform dispersion of iron ions and their formation of synergistic active sites with manganese ions. This allows the catalytic oxidation function of manganese ions to fully cooperate with the adsorption and fixation function of iron ions, significantly improving sulfur capacity and desulfurization accuracy, and avoiding uneven distribution of active sites or functional failure due to improper ligand ratios.

[0047] In a preferred embodiment of the present invention, the molar ratio of the sum of the iron ions in the iron salt and the manganese ions in the manganese salt to the molar ratio of the α-cyclodextrin is 1:(0.1–0.5:).

[0048] In this invention, from the perspective of metal ion complexation and dispersion, this ratio allows α-cyclodextrin to fully exert its complexing effect. α-Cyclodextrin interacts with Fe through its own hydroxyl groups, ether bonds, and other groups. 3+ Mn 2+The formation of complexes reduces the concentration of free metal ions in solution 2, preventing agglomeration due to rapid coordination caused by excessively high local concentrations when added to solution 1. If the molar ratio of α-cyclodextrin is less than 0.1:1, i.e., insufficient dosage, its complexing ability is limited and cannot cover most of the metal ions. Excessive free metal ions will still lead to bimetallic aggregation, disrupting the uniformity of distribution and masking some active sites. However, when the ratio is between 0.1 and 0.5:1, α-cyclodextrin can form a reasonable complex ratio with the total amount of bimetal, effectively reducing the concentration of free ions and slowly releasing metal ions under the influence of the polarity difference at the two-phase interface, ensuring uniform coordination with benzoic acid ligands and guaranteeing the uniform dispersion of bimetal in the MOF precursor.

[0049] From the perspective of inhibiting metal ion hydrolysis and reducing impurity formation, this ratio can achieve precise control of hydrolysis inhibition. Fe 3+ Mn 2+ Hydrolysis is easily conducted in aqueous solutions, generating amorphous Fe(OH)3, Mn(OH)2, and other impurities, affecting the purity of the precursor and the performance of the desulfurizer. The complexation effect of α-cyclodextrin can encapsulate metal ions, blocking the hydrolysis reaction. A ratio of 1:(0.1–0.5) ensures sufficient complexation coverage of α-cyclodextrin, effectively inhibiting the hydrolysis tendency of most metal ions. If the proportion of α-cyclodextrin is too low, the hydrolysis inhibition effect is insufficient, and the amount of impurities generated increases; if the proportion is higher than 0.5:1, excessive α-cyclodextrin will over-encapsulate metal ions, hindering their coordination reaction with benzoic acid ligands, leading to incomplete binary metal-organic framework construction, structural defects, and affecting the stability and activity of the desulfurizer.

[0050] From the perspective of micropore construction and framework compatibility after thermal decomposition, this ratio can balance adsorption sites and structural stability. The thermal decomposition products of α-cyclodextrin are small molecules such as CO2 and H2O, with no residual impurities, and leave micropores that match their own cavity size, providing additional sites for sulfide adsorption. At a ratio of 1:(0.1–0.5), the amount of α-cyclodextrin ensures that the number of micropores formed after decomposition is moderate and uniformly distributed, and that the micropore size complements the pore structure of the binary metal-organic framework. This avoids insufficient adsorption sites due to too few micropores, and also prevents the mechanical strength and structural integrity of the framework from being compromised by too many or too large micropores. If α-cyclodextrin is excessive, the micropore density after thermal decomposition will be too high, potentially leading to a loose and easily collapsed framework, reducing the durability of the desulfurizer in industrial applications. If the amount is insufficient, the micropore gain will be limited, failing to fully enhance the adsorption capacity for sulfides such as H2S and SO2.

[0051] Furthermore, this ratio range can also accommodate the molar ratio of iron ions to manganese ions in the range of (1–15):1. Regardless of how the internal ratio of the bimetal is adjusted, the total number of moles and the 1:(0.1–0.5) ratio of α-cyclodextrin ensure that the function of α-cyclodextrin is not affected by the change in the bimetal ratio, and it always stably performs its complexing, dispersing, and hydrolysis-inhibiting functions. This ensures that the desulfurizers prepared under different bimetal ratios have a consistent high-performance foundation, and maximizes the combination of the synergistic effect of bimetal and the auxiliary function of α-cyclodextrin.

[0052] In a preferred embodiment of the present invention, the organic solvent includes N,N One or more of dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, or methanol.

[0053] In this invention, the organic solvent is, for example, N,N Dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, methanol, N,N-dimethylformamide and dimethyl sulfoxide, N,N-dimethylformamide and N-methylpyrrolidone, N,N-dimethylformamide and methanol, dimethyl sulfoxide and N-methylpyrrolidone, dimethyl sulfoxide and methanol, or a combination of N-methylpyrrolidone and methanol.

[0054] In a preferred embodiment of the present invention, the iron salts include ferric chloride hexahydrate, ferric nitrate nonahydrate, ferric sulfate nonahydrate, or anhydrous ferric chloride; the manganese salts include manganese chloride tetrahydrate, manganese nitrate hexahydrate, manganese sulfate monohydrate, or anhydrous manganese chloride.

[0055] In this invention, the iron salt is, for example, ferric chloride hexahydrate, ferric nitrate nonahydrate, ferric sulfate nonahydrate, anhydrous ferric chloride, ferric chloride hexahydrate and ferric nitrate nonahydrate, ferric chloride hexahydrate and ferric sulfate nonahydrate, ferric chloride hexahydrate and anhydrous ferric chloride, ferric nitrate nonahydrate and ferric sulfate nonahydrate, ferric nitrate nonahydrate and anhydrous ferric chloride, ferric sulfate nonahydrate and anhydrous ferric chloride, ferric chloride hexahydrate, ferric nitrate nonahydrate and ferric sulfate nonahydrate, ferric chloride hexahydrate, ferric nitrate nonahydrate and anhydrous ferric chloride, ferric chloride hexahydrate, ferric sulfate nonahydrate and anhydrous ferric chloride, or a combination of ferric nitrate nonahydrate, ferric sulfate nonahydrate and anhydrous ferric chloride.

[0056] Manganese salts include, for example, manganese chloride tetrahydrate, manganese nitrate hexahydrate, manganese sulfate monohydrate, anhydrous manganese chloride, manganese chloride tetrahydrate and manganese nitrate hexahydrate, manganese chloride tetrahydrate and manganese sulfate monohydrate, manganese chloride tetrahydrate and anhydrous manganese chloride, manganese nitrate hexahydrate and manganese sulfate monohydrate, manganese nitrate hexahydrate and anhydrous manganese chloride, manganese sulfate monohydrate and anhydrous manganese chloride, manganese chloride tetrahydrate, manganese nitrate hexahydrate and manganese sulfate monohydrate, manganese chloride tetrahydrate, manganese nitrate hexahydrate and anhydrous manganese chloride, manganese chloride tetrahydrate, manganese sulfate monohydrate and anhydrous manganese chloride, or combinations of manganese nitrate hexahydrate, manganese sulfate monohydrate and anhydrous manganese chloride.

[0057] In a preferred embodiment of the present invention, calcination is carried out in a tube furnace for 1.5-3 hours.

[0058] In this invention, a tubular furnace is chosen for calcination because it can precisely control the temperature field and protective atmosphere, avoiding local overheating of the precursor or incomplete decomposition of ligands. Simultaneously, it isolates the metal ions from air to prevent oxidation, ensuring the directional generation of active oxides. Its stable isothermal zone can also meet the multi-step conversion requirements of the precursor, balancing laboratory-scale testing with industrial production, ensuring stable performance of different batches of desulfurizer. Calcination is a prerequisite for α-cyclodextrin to exert its subsequent effects. In solution, α-cyclodextrin achieves uniform dispersion of metal ions and inhibits hydrolysis through complexation, but it itself needs complete decomposition through calcination—its thermal decomposition products are small molecules such as CO2 and H2O without residue. This avoids organic residue contamination of the desulfurizer and leaves micropores matching its own cavity size after decomposition, providing additional adsorption sites for sulfides such as H2S. Without calcination, α-cyclodextrin will coat the surface of metal ions, hindering further coordination with benzoic acid ligands and preventing the formation of microporous structures, thus limiting its adsorption capacity.

[0059] The spinel structure of MnFe2O4 requires Fe 3+ With Mn 2+ At high temperatures, a redox reaction occurs and the precursor is formed through directional coordination, while Fe in the precursor... 3+ With Mn 2+Although pre-dispersed with α-cyclodextrin, calcination is still required to provide reaction energy to overcome interfacial resistance and achieve uniform contact and crystallization. The spinel structure of MnFe2O4 serves as the core catalytic active center, capable of catalytically oxidizing adsorbed H2S to elemental sulfur, overcoming the capacity limitations of single physical adsorption. Uncalcined precursors cannot form this active structure, resulting in a significant decrease in desulfurization efficiency. The coordination bonds between benzoic acid ligands and metal ions in the precursor need to be further strengthened at high temperatures to form a robust three-dimensional framework. This framework supports the micropores left after α-cyclodextrin decomposition, preventing their collapse, and also improves the hydrothermal stability and mechanical strength of the desulfurizer, making it more resistant to the moisture environment of industrial gases. Simultaneously, calcination removes residual solvents, unreacted trace ligands, and other impurities from the precursor, ensuring the purity of the active sites in the spinel structure of MnFe2O4 and preventing impurities from obscuring or interfering with the catalytic reaction.

[0060] The complete decomposition of α-cyclodextrin requires a certain amount of time. If it takes less than 1.5 hours, the decomposition is incomplete, and the residual organic matter will clog the micropores or encapsulate the active sites of the spinel structure of MnFe2O4. At the same time, the undecomposed α-cyclodextrin will hinder the Fe... 3+ With Mn 2+ The diffusion of MnFe2O4 leads to insufficient MnFe2O4 formation, low crystallinity, and limited catalytic activity. Directional crystallization of MnFe2O4 also requires more than 1.5 hours to complete, ensuring the formation of a complete spinel structure and avoiding catalytic site defects due to incomplete reaction. Three hours is the upper limit to avoid over-reaction. If the calcination time exceeds 3 hours, the high temperature will cause the binary metal-organic framework to shrink or even collapse, and the micropores formed after the decomposition of α-cyclodextrin will be destroyed due to the loss of framework support, resulting in a reduction of adsorption sites. Simultaneously, excessive high temperature will cause excessive growth and aggregation of MnFe2O4 particles, obscuring their catalytic active sites and weakening the synergistic effect of micropore adsorption and catalytic oxidation. Furthermore, prolonged calcination may also cause side reactions between trace carbon species remaining from the decomposition of α-cyclodextrin and metal ions, affecting the purity of the desulfurizer. The 1.5-3 hour range allows for a precise match between the micropore gain of α-cyclodextrin and the catalytic activity of MnFe2O4. Within this timeframe, the micropores formed by the decomposition of α-cyclodextrin complement the pore structure of the binary framework itself, constructing a hierarchical pore system. Simultaneously, MnFe2O4 is uniformly anchored around the micropores, forming an integrated adsorption-catalysis structure. After H2S is adsorbed by the micropores, it is rapidly transferred to the adjacent MnFe2O4 active centers, catalyzing its oxidation to elemental sulfur.

[0061] According to a third aspect of the present invention, a solid desulfurizer prepared by the preparation method described above is provided.

[0062] According to a third aspect of the invention, an application of a solid desulfurizing agent is provided, said desulfurizing agent being used to remove hydrogen sulfide from industrial gases;

[0063] The industrial gas is selected from at least one of natural gas, biogas, refinery gas, chemical synthesis gas, and coal-fired flue gas.

[0064] In a preferred embodiment of the present invention, after the solid desulfurizer is saturated with adsorption, it is regenerated by purging with a thermal inert gas; the conditions for purging with the thermal inert gas are: temperature 160-200℃, time 3-5h, and the thermal inert gas is high-purity nitrogen.

[0065] Example 1

[0066] Preparation of solution 1: Weigh 4.0 mmol of terephthalic acid and dissolve it in a mixed solvent of 30 mL of N,N-dimethylformamide (DMF) and 10 mL of methanol. Stir until completely dissolved to obtain solution 1.

[0067] Preparation of Solution 2: Weigh 1.875 mmol of ferric chloride hexahydrate (Fe3+) 3+ ) and 0.125 mmol manganese chloride tetrahydrate (Mn 2+ Add 0.4 mmol of α-cyclodextrin, dissolve in 10 mL of deionized water, and stir until clear to obtain solution 2 (Fe). 3+ :Mn 2+ =15:1 (the molar ratio of terephthalic acid to iron ions is 2.1:1).

[0068] Mixed reaction and precursor preparation: Under 300W ultrasonic conditions, solution 2 was added dropwise to solution 1, and the ultrasonic reaction was continued for 2 hours after the addition was completed; then the mixture was centrifuged at 3000 rpm for 10 minutes, the precipitate was collected, washed 3 times with deionized water, and dried in a 30℃ oven for 12 hours to obtain precursor M.

[0069] Preparation of desulfurizing agent by calcination: The precursor M is placed in a tube furnace and heated to 400-450℃ at 5℃ / min under a high-purity nitrogen protective atmosphere. It is calcined for 1.5h and then naturally cooled to obtain a solid desulfurizing agent.

[0070] Example 2

[0071] Preparation of solution 1: Weigh 4.0 mmol of terephthalic acid, dissolve it in 40 mL of LDM, and stir until completely dissolved to obtain solution 1;

[0072] Preparation of Solution 2: Weigh 1.6 mmol of ferric chloride hexahydrate and 0.4 mmol of manganese chloride tetrahydrate, add 0.5 mmol of α-cyclodextrin, dissolve in 10 mL of deionized water, and stir until clear to obtain Solution 2 (Fe 3+ :Mn 2+ =4:1 (the molar ratio of terephthalic acid to iron ions is 2.5:1).

[0073] Mixed reaction and precursor preparation: Under 300W ultrasonic conditions, solution 2 was added dropwise to solution 1, and the ultrasonic reaction was continued for 2 hours after the addition was completed; then the mixture was centrifuged at 3000 rpm for 10 minutes, the precipitate was collected, washed 3 times with deionized water, and dried in a 30℃ oven for 12 hours to obtain precursor M.

[0074] Preparation of desulfurizing agent by calcination: The precursor M is placed in a tube furnace and heated to 400-450℃ at 5℃ / min under a high-purity nitrogen protective atmosphere. After calcination for 2 hours, the solid desulfurizing agent is obtained after natural cooling.

[0075] Example 3

[0076] Preparation of Solution 1: Weigh 4.0 mmol of isophthalic acid and dissolve it in a mixed solvent of 20 mL of dimethyl sulfoxide (DMSO) and 20 mL of N-methylpyrrolidone (NMP). Stir until completely dissolved to obtain Solution 1.

[0077] Preparation of Solution 2: Weigh 1.71 mmol of ferric nitrate nonahydrate and 0.21 mmol of manganese nitrate hexahydrate, add 0.6 mmol of α-cyclodextrin, dissolve in 10 mL of deionized water, and stir until clear to obtain Solution 2 (Fe 3+ :Mn 2+ =8:1 (the molar ratio of isophthalic acid to iron ions is 2.3:1).

[0078] Mixed reaction and precursor preparation: Under 300W ultrasonic conditions, solution 2 was added dropwise to solution 1, and the ultrasonic reaction was continued for 2 hours after the addition was completed; then the mixture was centrifuged at 3000 rpm for 10 minutes, the precipitate was collected, washed 3 times with deionized water, and dried in a 30℃ oven for 12 hours to obtain precursor M.

[0079] Preparation of desulfurizing agent by calcination: The precursor M is placed in a tube furnace and heated to 400-450℃ at 5℃ / min under a high-purity nitrogen protective atmosphere. It is calcined for 2.5h and then naturally cooled to obtain a solid desulfurizing agent.

[0080] Example 4

[0081] Preparation of solution 1: Weigh 4.0 mmol of phthalic acid, dissolve it in 40 mL of NMP, and stir until completely dissolved to obtain solution 1;

[0082] Preparation of Solution 2: Weigh 1.0 mmol of anhydrous ferric chloride and 1.0 mmol of manganese sulfate monohydrate, add 1.0 mmol of α-cyclodextrin, dissolve in 10 mL of deionized water, and stir until clear to obtain Solution 2 (Fe 3+ :Mn 2+ =1:1 (the molar ratio of phthalic acid to iron ions is 4:1).

[0083] Mixed reaction and precursor preparation: Under 300W ultrasonic conditions, solution 2 was added dropwise to solution 1, and the ultrasonic reaction was continued for 2 hours after the addition was completed; then the mixture was centrifuged at 3000 rpm for 10 minutes, the precipitate was collected, washed 3 times with deionized water, and dried in a 30℃ oven for 12 hours to obtain precursor M.

[0084] Preparation of desulfurizing agent by calcination: The precursor M is placed in a tube furnace and heated to 400-450℃ at 5℃ / min under a high-purity nitrogen protective atmosphere. After calcination for 3 hours, the solid desulfurizing agent is obtained after natural cooling.

[0085] Example 5

[0086] Preparation of solution 1: Weigh 4.0 mmol of 5-hydroxyisophthalic acid, dissolve it in 40 mL of DMSO, and stir until completely dissolved to obtain solution 1;

[0087] Preparation of Solution 2: Weigh 1.6 mmol of ferric sulfate nonahydrate and 0.4 mmol of anhydrous manganese chloride, add 0.3 mmol of α-cyclodextrin, dissolve in 10 mL of deionized water, and stir until clear to obtain Solution 2 (Fe 3+ :Mn 2+ =4:1 (the molar ratio of 5-hydroxyisophthalic acid to iron ions is 2.5:1).

[0088] Mixed reaction and precursor preparation: Under 300W ultrasonic conditions, solution 2 was added dropwise to solution 1, and the ultrasonic reaction was continued for 2 hours after the addition was completed; then the mixture was centrifuged at 3000 rpm for 10 minutes, the precipitate was collected, washed 3 times with deionized water, and dried in a 30℃ oven for 12 hours to obtain precursor M.

[0089] Preparation of desulfurizing agent by calcination: The precursor M is placed in a tube furnace and heated to 400-450℃ at 5℃ / min under a high-purity nitrogen protective atmosphere. After calcination for 2 hours, the solid desulfurizing agent is obtained after natural cooling.

[0090] Example 6

[0091] Preparation of solution 1: Weigh 4.0 mmol of terephthalic acid and dissolve it in a mixed solvent of 20 mL of DMF and 20 mL of DMSO. Stir until completely dissolved to obtain solution 1.

[0092] Preparation of Solution 2: Weigh 0.9 mmol ferric chloride hexahydrate and 0.6 mmol ferric nitrate nonahydrate (total 1.5 mmol Fe) 3 + ), along with 0.25 mmol manganese chloride tetrahydrate and 0.25 mmol manganese nitrate hexahydrate (total 0.5 mmol Mn), 2+Add 0.2 mmol of α-cyclodextrin, dissolve together in 10 mL of deionized water, and stir until clear to obtain solution 2 (Fe). 3+ :Mn 2+ =3:1 (the molar ratio of terephthalic acid to iron ions is 2.7:1).

[0093] Mixed reaction and precursor preparation: Under 300W ultrasonic conditions, solution 2 was added dropwise to solution 1, and the ultrasonic reaction was continued for 2 hours after the addition was completed; then the mixture was centrifuged at 3000 rpm for 10 minutes, the precipitate was collected, washed 3 times with deionized water, and dried in a 30℃ oven for 12 hours to obtain precursor M.

[0094] Preparation of desulfurizing agent by calcination: The precursor M is placed in a tube furnace and heated to 400-450℃ at 5℃ / min under a high-purity nitrogen protective atmosphere. After calcination for 2 hours, the solid desulfurizing agent is obtained after natural cooling.

[0095] Example 7

[0096] Preparation of solution 1: Weigh 4.0 mmol of terephthalic acid (ligand to iron ion molar ratio 2:1), dissolve it in 30 mL of N,N-dimethylformamide (DMF), and stir until completely dissolved to obtain solution 1;

[0097] Preparation of Solution 2: Weigh 1.818 mmol of ferric nitrate nonahydrate and 0.182 mmol of manganese nitrate hexahydrate (Fe 3+ :Mn 2+ =10:1), add 0.2 mmol of α-cyclodextrin (total molar ratio of bimetallic metal to α-cyclodextrin = 1:0.1), dissolve together in 10 mL of deionized water, stir until clear, to obtain solution 2;

[0098] Mixed reaction and precursor preparation: Under 300W ultrasonic conditions, solution 2 was added dropwise to solution 1, and the ultrasonic reaction was continued for 2 hours after the addition was completed; then the mixture was centrifuged at 3000 rpm for 10 minutes, the precipitate was collected, washed 3 times with deionized water, and dried in a 30℃ oven for 12 hours to obtain precursor M.

[0099] Preparation of desulfurizing agent by calcination: The precursor M is placed in a tube furnace and heated to 400-450℃ at 5℃ / min under a high-purity nitrogen protective atmosphere. After calcination for 2 hours, the solid desulfurizing agent is obtained after natural cooling.

[0100] Example 8

[0101] Preparation of solution 1: Weigh 6.0 mmol of isophthalic acid (ligand to iron ion molar ratio 3:1), dissolve it in a mixed solvent of 20 mL LDM and 20 mL dimethyl sulfoxide (DMSO), and stir until completely dissolved to obtain solution 1;

[0102] Preparation of Solution 2: Weigh 1.714 mmol of ferric chloride hexahydrate and 0.286 mmol of manganese chloride tetrahydrate (Fe 3+ :Mn 2+ =6:1), add 0.6 mmol of α-cyclodextrin (total molar ratio of bimetallic metal to α-cyclodextrin = 1:0.3), dissolve together in 10 mL of deionized water, stir until clear, to obtain solution 2;

[0103] Mixed reaction and precursor preparation: Same as step 3 in Example 7;

[0104] Preparation of desulfurizing agent by calcination: Same as step 4 in Example 7 (calcination time 2h).

[0105] Example 9

[0106] Preparation of solution 1: Weigh 7.0 mmol of 5-hydroxyisophthalic acid (ligand to iron ion molar ratio 3.5:1), dissolve it in a mixed solvent of 30 mL N-methylpyrrolidone (NMP) and 10 mL methanol, and stir until completely dissolved to obtain solution 1;

[0107] Preparation of Solution 2: Weigh 1.846 mmol of anhydrous ferric chloride and 0.154 mmol of anhydrous manganese chloride (Fe3+). 3+ :Mn 2+ =12:1), add 1.0 mmol of α-cyclodextrin (total molar ratio of bimetallic metal to α-cyclodextrin = 1:0.5), dissolve together in 10 mL of deionized water, stir until clear, to obtain solution 2;

[0108] Mixed reaction and precursor preparation: Same as step 3 in Example 7;

[0109] Preparation of desulfurizing agent by calcination: Same as step 4 in Example 7 (calcination time 2.5h).

[0110] Example 10

[0111] Preparation of solution 1: Weigh 8.0 mmol of phthalic acid (ligand to iron ion molar ratio 4:1), dissolve it in 40 mL of methanol (single organic solvent), and stir until completely dissolved (ultrasonic dissolution for 30 min) to obtain solution 1;

[0112] Preparation of Solution 2: Weigh 1.667 mmol of ferric sulfate nonahydrate and 0.333 mmol of manganese sulfate monohydrate (Fe). 3+ :Mn 2+ =5:1), add 0.4 mmol of α-cyclodextrin (total molar ratio of bimetallic metal to α-cyclodextrin = 1:0.2), dissolve together in 10 mL of deionized water, stir until clear, to obtain solution 2;

[0113] Mixed reaction and precursor preparation: Same as step 3 in Example 7;

[0114] Preparation of desulfurizing agent by calcination: Same as step 4 in Example 7 (calcination time 2h).

[0115] Comparative Example 1

[0116] Preparation of solution 1: Weigh 4.0 mmol of terephthalic acid, dissolve it in 40 mL of LDM, and stir until completely dissolved to obtain solution 1;

[0117] Preparation of solution 2: Weigh 2.0 mmol of ferric chloride hexahydrate, dissolve it in 10 mL of deionized water, and stir until clear to obtain solution 2;

[0118] Mixed reaction and precursor preparation: Under 300W ultrasonic conditions, solution 2 was added dropwise to solution 1, and the ultrasonic reaction was continued for 2 hours after the addition was completed; then the mixture was centrifuged at 3000 rpm for 10 minutes, the precipitate was collected, washed 3 times with deionized water, and dried in a 30℃ oven for 12 hours to obtain precursor M.

[0119] Preparation of desulfurizing agent by calcination: The precursor M is placed in a tube furnace and heated to 400-450℃ at 5℃ / min under a high-purity nitrogen protective atmosphere. After calcination for 2 hours, the solid desulfurizing agent is obtained after natural cooling.

[0120] Comparative Example 2

[0121] Preparation of solution 1: Weigh 4.0 mmol of terephthalic acid, dissolve it in 40 mL of LDM, and stir until completely dissolved to obtain solution 1;

[0122] Preparation of solution 2: Weigh 2.0 mmol of manganese chloride tetrahydrate, dissolve it in 10 mL of deionized water, and stir until clear to obtain solution 2;

[0123] Mixed reaction and precursor preparation: Under 300W ultrasonic conditions, solution 2 was added dropwise to solution 1, and the ultrasonic reaction was continued for 2 hours after the addition was completed; then the mixture was centrifuged at 3000 rpm for 10 minutes, the precipitate was collected, washed 3 times with deionized water, and dried in a 30℃ oven for 12 hours to obtain precursor M.

[0124] Preparation of desulfurizing agent by calcination: The precursor M is placed in a tube furnace and heated to 400-450℃ at 5℃ / min under a high-purity nitrogen protective atmosphere. After calcination for 2 hours, the solid desulfurizing agent is obtained after natural cooling.

[0125] Comparative Example 3

[0126] Preparation of solution 1: Weigh 4.0 mmol of oxalic acid, dissolve it in 40 mL of DMF, and stir until completely dissolved to obtain solution 1;

[0127] Preparation of Solution 2: Weigh 1.6 mmol of ferric chloride hexahydrate and 0.4 mmol of manganese chloride tetrahydrate, dissolve them in 10 mL of deionized water, and stir until clear to obtain Solution 2 (Fe 3+ :Mn 2+ =4:1).

[0128] Mixed reaction and precursor preparation: Under 300W ultrasonic conditions, solution 2 was added dropwise to solution 1, and the ultrasonic reaction was continued for 2 hours after the addition was completed; then the mixture was centrifuged at 3000 rpm for 10 minutes, the precipitate was collected, washed 3 times with deionized water, and dried in a 30℃ oven for 12 hours to obtain precursor M.

[0129] Preparation of desulfurizing agent by calcination: The precursor M is placed in a tube furnace and heated to 400-450℃ at 5℃ / min under a high-purity nitrogen protective atmosphere. After calcination for 2 hours, the solid desulfurizing agent is obtained after natural cooling.

[0130] Comparative Example 4

[0131] Preparation of solution 1: Weigh 4.0 mmol of terephthalic acid, dissolve it in 40 mL of LDM, and stir until completely dissolved to obtain solution 1;

[0132] Preparation of Solution 2: Weigh 0.67 mmol ferric chloride hexahydrate and 1.33 mmol manganese chloride tetrahydrate, dissolve them in 10 mL of deionized water, and stir until clear to obtain Solution 2 (Fe 3+ :Mn 2+ =0.5:1).

[0133] Mixed reaction and precursor preparation: Under 300W ultrasonic conditions, solution 2 was added dropwise to solution 1, and the ultrasonic reaction was continued for 2 hours after the addition was completed; then the mixture was centrifuged at 3000 rpm for 10 minutes, the precipitate was collected, washed 3 times with deionized water, and dried in a 30℃ oven for 12 hours to obtain precursor M.

[0134] Preparation of desulfurizing agent by calcination: The precursor M is placed in a tube furnace and heated to 400-450℃ at 5℃ / min under a high-purity nitrogen protective atmosphere. After calcination for 2 hours, the solid desulfurizing agent is obtained after natural cooling.

[0135] Comparative Example 5

[0136] Preparation of solution 1: Weigh 4.0 mmol of terephthalic acid, dissolve it in 40 mL of LDM, and stir until completely dissolved to obtain solution 1;

[0137] Preparation of solution 2: Weigh 0.8 mmol of ferric chloride hexahydrate and 0.2 mmol of manganese chloride tetrahydrate, dissolve them in 10 mL of deionized water, and stir until clear to obtain solution 2 (the molar ratio of terephthalic acid to ferric ions is 5:1).

[0138] Mixed reaction and precursor preparation: Under 300W ultrasonic conditions, solution 2 was added dropwise to solution 1, and the ultrasonic reaction was continued for 2 hours after the addition was completed; then the mixture was centrifuged at 3000 rpm for 10 minutes, the precipitate was collected, washed 3 times with deionized water, and dried in a 30℃ oven for 12 hours to obtain precursor M.

[0139] Preparation of desulfurizing agent by calcination: The precursor M is placed in a tube furnace and heated to 400-450℃ at 5℃ / min under a high-purity nitrogen protective atmosphere. After calcination for 2 hours, the solid desulfurizing agent is obtained after natural cooling.

[0140] Comparative Example 6

[0141] Preparation without solution 1: Prepare an aqueous solution of metal salt directly without adding benzoic acid-based organic ligands;

[0142] Preparation of solution 2: Weigh 1.6 mmol ferric chloride hexahydrate and 0.4 mmol manganese chloride tetrahydrate, dissolve them in 10 mL of deionized water, and stir until clear to obtain solution 2 (no ligands, unable to form metal-organic frameworks).

[0143] Processing steps: Centrifuge solution 2 at 3000 rpm for 10 min (no reaction mixing step), collect the precipitate, wash it 3 times with deionized water, and dry it in a 30℃ oven for 12 h to obtain a solid;

[0144] Calcination treatment: The above solid is placed in a tube furnace and heated to 400-450℃ at a rate of 5℃ / min under a high-purity nitrogen protective atmosphere. It is calcined for 2 hours and then naturally cooled to obtain the solid.

[0145] Comparative Example 7

[0146] Preparation of solution 1: Weigh 4.0 mmol of terephthalic acid (ligand to iron ion molar ratio 2.5:1), dissolve it in 40 mL of LDM, and stir until completely dissolved to obtain solution 1;

[0147] Preparation of Solution 2: Weigh 1.6 mmol of ferric chloride hexahydrate and 0.4 mmol of manganese chloride tetrahydrate (Fe 3+ :Mn 2+ =4:1), add 0.1 mmol of α-cyclodextrin (total molar ratio of bimetallic metal to α-cyclodextrin = 1:0.05), dissolve together in 10 mL of deionized water, stir until clear, to obtain solution 2;

[0148] Mixed reaction and precursor preparation: Same as step 3 in Example 7;

[0149] Preparation of desulfurizing agent by calcination: Same as step 4 in Example 7.

[0150] Comparative Example 8

[0151] Preparation of solution 1: Same as step 1 of Comparative Example 7;

[0152] Preparation of Solution 2: Weigh 1.6 mmol of ferric chloride hexahydrate and 0.4 mmol of manganese chloride tetrahydrate (Fe 3+ :Mn 2+ =4:1), add 1.2 mmol of α-cyclodextrin (total molar ratio of bimetallic metal to α-cyclodextrin = 1:0.6), dissolve together in 10 mL of deionized water, stir until clear, to obtain solution 2;

[0153] Mixed reaction and precursor preparation: Same as step 3 in Example 7;

[0154] Preparation of desulfurizing agent by calcination: Same as step 4 in Example 7.

[0155] Comparative Example 9

[0156] Preparation of solution 1: Same as step 1 in Example 2;

[0157] Preparation of solution 2: Same as step 2 in Example 2;

[0158] Mixed reaction and precursor preparation: Same as step 3 in Example 2;

[0159] Preparation of desulfurizing agent by calcination: The precursor M is placed in a tube furnace and heated to 400-450℃ at 5℃ / min under a high-purity nitrogen protective atmosphere. After calcination for 1 hour, the solid desulfurizing agent is obtained after natural cooling.

[0160] Comparative Example 10

[0161] Preparation of solutions 1-3: Same as steps 1-3 in Example 2;

[0162] Preparation of desulfurizing agent by calcination: calcination time 4h, other conditions are the same as in Example 2.

[0163] Comparative Example 11

[0164] Preparation of solution 1: Weigh 3.0 mmol of terephthalic acid (ligand to iron ion molar ratio 1.5:1), dissolve it in 40 mL of LDM, and stir until completely dissolved to obtain solution 1;

[0165] Preparation of solution 2: Weigh 2.0 mmol of ferric chloride hexahydrate, dissolve it in 10 mL of deionized water, and stir until clear to obtain solution 2;

[0166] Mixed reaction and precursor preparation: Same as step 3 in Example 7;

[0167] Preparation of desulfurizing agent by calcination: Same as step 4 in Example 7.

[0168] Performance testing

[0169] The materials prepared in the examples and comparative examples were ground, and 0.5 g of each 40-60 mesh particle was packed into a fixed-bed adsorption tube. The simulated natural gas composition was 94% CH4, 5% CO2, and 1% H2S (volume fraction), with a gas hourly space velocity of 2000 h⁻¹. - ¹, At a temperature of 50℃ and a pressure of 1.0MPa, the outlet H2S concentration was monitored to the breakthrough (1ppm) using an online gas chromatograph and sulfur chemiluminescence detector, and the breakthrough sulfur capacity was measured.

[0170] The desulfurizing agent saturated in the examples and comparative examples was removed and purged with high-purity nitrogen at 180°C for 4 hours to remove water vapor and some volatile sulfur species from the pores. The regenerated material underwent a second round of desulfurization testing. After three adsorption-regeneration cycles, the sulfur capacity retention rate was measured. Sulfur capacity retention rate (%) = (sulfur capacity after the third regeneration / initial sulfur capacity) × 100%.

[0171] The test results are shown in Table 1:

[0172]

[0173] The bimetallic synergistic system is the core foundation for desulfurizers to achieve high sulfur capacity and high regeneration stability. Fe³ + It possesses stable framework construction capabilities, enabling the construction of robust binary metal-organic framework structures to provide structural support for desulfurization; Mn 2+ It possesses excellent catalytic oxidation activity, efficiently converting adsorbed hydrogen sulfide into elemental sulfur, overcoming the capacity limitations of single physical adsorption. The synergistic effect of both allows the desulfurizer to simultaneously possess physical adsorption, chemical adsorption, and catalytic oxidation functions. This is the key reason why the sulfur capacity in the examples generally reaches 5.3 to 6.9 mmol / g, and the sulfur capacity retention rate remains at 84% to 88% after three regenerations. In contrast, the comparative examples using a single iron system or a single manganese system have a sulfur capacity of only 1.8 to 2.5 mmol / g and a retention rate of less than 60%, fully demonstrating the irreplaceable nature of bimetallic synergy.

[0174] The precise addition of α-cyclodextrin is a key aid in improving system performance. Its synergistic ratio with bimetals and ligands directly determines the structural integrity and activity efficiency of the desulfurizer. α-Cyclodextrin can form complexes with iron and manganese ions, effectively reducing the concentration of free metal ions in the solution and preventing metal agglomeration during subsequent coordination, allowing the bimetal to be uniformly dispersed within the framework. Simultaneously, it inhibits metal ion hydrolysis, reduces the formation of impurities such as amorphous hydroxides, and ensures precursor purity. During calcination, α-cyclodextrin decomposes into residue-free small molecules, leaving micropores that match its own cavity size. These micropores complement the binary metal-organic framework, significantly increasing adsorption sites. The desulfurizer performs optimally when the ratio of α-cyclodextrin to the total amount of bimetal is within the compliant range of 1:0.1 to 1:0.5. Once the ratio is below 0.1 or above 0.5, the sulfur capacity drops sharply to 2.8 to 3.1 mmol / g, with a retention rate of only 52% to 56%, and the adsorption-catalysis synergistic effect is completely lost.

[0175] Calcination is essential for the formation of an effective active structure in desulfurizers, and its temperature and time control directly affect the final performance. The protective atmosphere provided by the tubular furnace prevents the precursor from being oxidized and avoids changes in the valence state of metal ions affecting desulfurization activity. During calcination, the coordination bonds between benzoic acid-based organic ligands and metal ions are strengthened, forming a robust three-dimensional framework that supports the micropores left after the decomposition of α-cyclodextrin and improves the hydrothermal stability and mechanical strength of the desulfurizer. Simultaneously, calcination provides sufficient energy for the formation of the MnFe₂O₄ spinel structure by iron and manganese ions, which is the core active center for the catalytic oxidation of hydrogen sulfide. A calcination time of 1.5 to 3 hours is optimal. Less than 1.5 hours leads to incomplete decomposition of α-cyclodextrin, low crystallinity of MnFe₂O₄, and a sulfur capacity of only 2.2 mmol / g; more than 3 hours causes framework collapse, micropore destruction, a decrease in sulfur capacity to 2.4 mmol / g, and a significant reduction in both catalytic activity and adsorption capacity.

[0176] The synergistic effect of these three components, along with the parameter range defined in the claims, constitutes the technical advantage of this invention. Compliance with the following parameters—an iron-manganese ratio of 1:1 to 15:1, a ligand-to-iron ion ratio of 2:1 to 4:1, a calcination time of 1.5 to 3 hours, and regeneration conditions of 160 to 200°C for 3 to 5 hours—ensures the efficient coordination of bimetallic synergy, α-cyclodextrin assistance, and the calcination process. This synergistic system addresses the pain points of existing wet desulfurization equipment (complexity, high energy consumption) and dry desulfurization (insufficient precision, difficult regeneration)—allowing the desulfurizing agent to possess high sulfur capacity, high regeneration stability, and the ability to deeply remove hydrogen sulfide. It is particularly suitable for the desulfurization treatment of industrial gases such as natural gas and biogas, and has significant industrial application value.

[0177] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a solid desulfurizing agent, characterized in that, Includes the following steps: Benzoic acid-based organic ligands were dissolved in an organic solvent to obtain solution 1; Iron salt, manganese salt and α-cyclodextrin were dissolved in water to obtain solution 2; Solution 2 was added to solution 1, and after mixing and reacting, the mixture was centrifuged, washed, and dried to obtain precursor M. Precursor M was calcined under a protective atmosphere to obtain a solid desulfurizing agent; The molar ratio of iron ions in the iron salt to manganese ions in the manganese salt is (1-15):1; The molar ratio of the benzoic acid-based organic ligand to the iron ion is (2-4):1; The molar ratio of the sum of the iron ions in the iron salt and the manganese ions in the manganese salt to the molar ratio of the α-cyclodextrin is 1:(0.1–0.5). The calcination is carried out in a tube furnace, with the temperature increased at 5℃ / min to 400-450℃, and calcined for 1.5-3 hours.

2. The preparation method according to claim 1, characterized in that, The benzoic acid-based organic ligands include one or more of isophthalic acid, phthalic acid, terephthalic acid, or 5-hydroxyisophthalic acid.

3. The preparation method according to claim 1, characterized in that, The iron salts include ferric chloride hexahydrate, ferric nitrate nonahydrate, ferric sulfate nonahydrate, or anhydrous ferric chloride. The manganese salts include manganese chloride tetrahydrate, manganese nitrate hexahydrate, manganese sulfate monohydrate, or anhydrous manganese chloride.

4. A solid desulfurizer prepared by the preparation method according to any one of claims 1-3.

5. The application of the solid desulfurizing agent as described in claim 4, characterized in that, The desulfurizing agent is used to remove hydrogen sulfide from industrial gases; The industrial gas is selected from at least one of natural gas, biogas, refinery gas, chemical synthesis gas, and coal-fired flue gas.

6. The application as described in claim 5, characterized in that, After the solid desulfurizing agent is saturated with adsorption, it is regenerated by purging with a thermal inert gas. The conditions for purging with the thermal inert gas are: temperature 160-200℃, time 3-5h, and the thermal inert gas is high-purity nitrogen.

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