A bifunctional aluminum-based desulfurizer and a preparation method thereof

Abstract

The application discloses a bifunctional aluminum-based desulfurizer and a preparation method thereof, and belongs to the technical field of environmental protection catalysts and energy gas purification. The preparation method comprises the following steps: mixing a supported aluminum-based catalyst, an alkali modifier and a solvent, then kneading, and adding a binder, a binding aid and a pore-expanding agent in sequence in the kneading process to obtain mixed kneaded materials; performing shaping treatment on the mixed kneaded materials to obtain a columnar aluminum-based catalyst precursor; performing vacuum drying on the columnar aluminum-based catalyst precursor to obtain a shaped aluminum-based catalyst precursor; and performing calcination on the shaped aluminum-based catalyst precursor in sequence under air atmosphere and ammonia gas atmosphere. The bifunctional aluminum-based desulfurizer has a COS removal efficiency of 100% under normal temperature to 180 DEG C and normal pressure to 8.0 MPa, the purified gas does not contain H2S, COS and H2S can be synchronously and deeply removed, and the bifunctional aluminum-based desulfurizer has high stability and sulfur poisoning resistance.

Description

Technical Field

[0001] This invention relates to the field of environmental protection catalysts and energy gas purification technology, and in particular to a bifunctional aluminum-based desulfurizer and its preparation method. Background Technology

[0002] Natural gas, as a high-quality, efficient, green, and clean low-carbon energy source, produces no solid waste upon complete combustion after purification, and its carbon dioxide emissions are significantly lower than those of other fossil fuels such as coal and oil. It occupies a core position in my country's energy structure transformation towards a cleaner and lower-carbon model. my country is rich in sulfur-containing gas fields, with those containing 2%–4% hydrogen sulfide (H2S) accounting for 60% of the country's total natural gas production. While the reserves of this type of sulfur-containing natural gas are considerable, its development and utilization face numerous challenges. Due to the high toxicity and corrosiveness of H2S, it poses serious safety hazards throughout the entire process of drilling, gas extraction, transmission, and end-use, while also damaging equipment and polluting the environment. Therefore, sulfur-containing natural gas must undergo rigorous purification and desulfurization treatment before it can be used commercially. Furthermore, converting the removed H2S into economically valuable sulfur resources, achieving resource recovery and efficient utilization of sulfur resources, is also key to improving the economic benefits of sulfur-containing natural gas development.

[0003] Currently, the traditional industrial natural gas desulfurization process mainly uses the amine method. This process can effectively remove H2S, carbon dioxide (CO2), and a small amount of organic sulfur from natural gas, meeting the minimum quality requirements for basic commercial natural gas. However, it has significant limitations. The chemical solvents used (such as methyldiethanolamine, MDEA) have low removal efficiency for organic sulfur, typically not exceeding 30%, making it difficult to meet higher purification standards. When the organic sulfur content in natural gas is high, the mainstream treatment process in the industry is the physicochemical solvent method. Although this method can improve the organic sulfur removal effect to some extent, it has poor selectivity and easily causes adsorption loss of effective components in natural gas, thereby reducing the recovery rate of commercial gas and increasing production costs. From a thermodynamic equilibrium perspective, the physicochemical solvent system can theoretically achieve an organic sulfur removal rate of over 95%. However, in actual industrial applications, due to limitations in operating parameters such as mass transfer efficiency, gas-liquid ratio, and contact time within the absorption tower, it is difficult for the gas-liquid contact to reach a thermodynamic equilibrium state, resulting in an organic sulfur removal rate far lower than the theoretical level, failing to meet the requirements for deep purification. With the rapid development of my country's economy and society, the demand for natural gas continues to rise. The country has imposed stricter requirements on the quality of natural gas products to meet the needs of end-users and increasingly stringent environmental standards. The national standard "Natural Gas" (GB 17820-2018) clearly stipulates that the H2S content in commercial natural gas must be <6mg / m³. 3 Total sulfur content <20mg / m³ 3Natural gas that does not meet this standard is strictly prohibited from entering long-distance pipelines. Therefore, deep desulfurization has become a core prerequisite and technical bottleneck for the commercialization of sulfur-containing natural gas.

[0004] Among the various components affecting the total sulfur content of commercial natural gas, carbonyl sulfide (COS) is a key limiting component, and its removal efficiency directly determines whether natural gas can meet national standards. Currently, COS removal methods are mainly divided into two categories: wet and dry methods. Wet methods primarily use liquid-phase absorption, but due to the inherently low chemical reactivity of COS, this method struggles to achieve the required fine desulfurization. Furthermore, the absorbent is prone to failure, subsequent treatment is difficult, and secondary pollution is easily generated, severely limiting its application. Dry methods, on the other hand, utilize adsorbents or catalysts to achieve deep COS removal through adsorption or chemical reactions, meeting the requirements for deep natural gas purification. These methods mainly include four technical pathways: adsorption, catalytic hydrolysis, hydrogenation reduction, and oxidation. Compared to other dry methods, catalytic hydrolysis converts COS into more easily removed H2S. It can achieve efficient COS conversion and removal under low-temperature conditions (≤100℃), offering significant advantages such as high conversion efficiency, low reaction temperature, no need for hydrogen source consumption, and no harmful byproducts. Therefore, it is currently the preferred process for deep COS removal from natural gas.

[0005] Currently, commercially available organic sulfur hydrolysis catalysts used in industry mainly include aluminum-based, titanium-based, zirconium-based, and carbon-based types. However, in actual production conditions of sulfur-containing natural gas, natural gas typically has high water content and high H2S content. Under these conditions, such commercial catalysts are prone to problems such as loss of active components, catalyst deactivation, and rapid decline in catalytic efficiency. Their COS catalytic hydrolysis effect is significantly limited, making it difficult to consistently meet the quality requirements for deep desulfurization and commercialization of natural gas. Simultaneously, the mechanical properties of desulfurizing agents need to be balanced for industrial applications. Therefore, developing molded desulfurizing agents with high catalytic activity, high water resistance, high sulfur resistance, and satisfactory mechanical properties has become a key technological breakthrough for overcoming the bottlenecks in deep natural gas desulfurization technology, improving natural gas purification efficiency, increasing commercial gas recovery rate, and promoting the efficient development and utilization of sulfur-containing natural gas resources. This has significant industrial application value and practical significance.

[0006] CN116020466A discloses a "COS conversion catalyst and its preparation method and method for recovering sulfur from natural gas". This technical solution uses an aluminum source, a pore-expanding agent, and a binder as starting components, and obtains an alumina support through mixing, drying, and calcination. Subsequently, by impregnating with alkali metal salt and nickel salt solutions, followed by drying and calcination, a composite desulfurizing agent simultaneously loaded with sodium oxide / potassium oxide and nickel oxide is successfully prepared. This desulfurizing agent has a volume hourly space velocity (VHSV) of 1000~5000 h⁻¹. -1Under reaction temperatures of 105-150℃, the highest desulfurization efficiency can reach 99.7%, demonstrating the potential for efficient desulfurization under low-temperature conditions. However, this process suffers from technical bottlenecks such as a lengthy preparation process and the need for external hydrogen supply, which to some extent limits its widespread application in practical industrial scenarios.

[0007] CN117414809B discloses "an organosulfur hydrolysis catalyst, its preparation method, and its application." This method involves preparing boehmite via a carbonization process, in which a water-soluble titanium-containing compound and a surfactant are added, and titanium-containing boehmite is obtained through a CO2 carbonization process. Finally, the titanium-containing boehmite is shaped to obtain the organosulfur hydrolysis catalyst. The catalyst's organosulfur hydrolysis activity conditions are: reaction temperature 320℃ and space velocity 5000 h⁻¹. -1 Although this catalyst can be used for the catalytic hydrolysis of CS2, its application in the catalytic hydrolysis of COS is not covered. Furthermore, the reaction temperature is relatively high, and the preparation process of the catalyst by carbonization requires continuous adjustment of the CO2 flow rate to change the solution pH, making the preparation process quite cumbersome.

[0008] CN121927427A discloses "a desulfurizing agent and its preparation method." The method involves amination modification of xanthan gum, followed by mixing it with nanocellulose, and then preparing a slurry with a metal salt solution containing Fe, Zn, and Ca. The precursor is obtained through bidirectional temperature gradient freeze casting and freeze-drying. Finally, the precursor is activated by calcination under programmed temperature control to obtain a columnar desulfurizing agent. This desulfurizing agent exhibits high sulfur capacity and mechanical strength, but it is only suitable for removing H2S from industrial gases.

[0009] In summary, existing patents address the problems of low service life, low selectivity of desulfurization products, poor resistance to sulfur poisoning, and low mechanical properties in natural gas organic sulfur hydrolysis catalysts. These solutions generally focus on improving catalyst adsorption performance and catalytic desulfurization efficiency, but they also suffer from complex preparation processes, high reaction temperatures required for the catalyst, low desulfurization precision, and short desulfurization life, which are not conducive to industrial production and application. Summary of the Invention

[0010] To address the aforementioned technical problems, this invention provides a bifunctional aluminum-based desulfurizer that can efficiently remove COS and H2S from natural gas, and also exhibits high selectivity for desulfurization products, resistance to sulfur poisoning, and long service life.

[0011] The further technical problem to be solved by the present invention is to provide a method for preparing a bifunctional aluminum-based desulfurizing agent.

[0012] To achieve the above objectives, the present invention adopts the following technical solution:

[0013] A method for preparing a bifunctional aluminum-based desulfurizer includes the following steps:

[0014] S1: The supported aluminum-based catalyst, alkali modifier, and solvent are mixed and kneaded. During the kneading process, a binder, a binding aid, and a pore-expanding agent are added sequentially to obtain a mixed kneaded material. The mixed kneaded material is shaped to obtain a columnar aluminum-based catalyst precursor. The columnar aluminum-based catalyst precursor is vacuum dried to obtain a shaped aluminum-based catalyst precursor. The mass ratio of the supported aluminum-based catalyst, alkali modifier, and solvent is 100:1~20:35~65; the mass ratio of the supported aluminum-based catalyst, binder, binding aid, and pore-expanding agent is 100:5~25:1~15:1~5.

[0015] S2: The shaped aluminum-based catalyst precursor is calcined in air atmosphere; the air calcination temperature is 500~900℃ and the air calcination time is 30~120min.

[0016] S3: The air-calcined shaped aluminum-based catalyst precursor is calcined in an ammonia atmosphere to obtain a bifunctional aluminum-based desulfurizer; the ammonia calcination temperature is 300~700℃ and the ammonia calcination time is 30~240min.

[0017] In step S1, the vacuum drying temperature is 60~95℃ and the vacuum drying time is 0.5~6h; the alkali modifier is one or more of KOH, NaOH, KHCO3, NaHCO3, K2CO3, and Na2CO3.

[0018] In step S1, the binder is a mixture of boehmite and aluminum nitrate, with a mass ratio of boehmite to aluminum nitrate of 100:1~10.

[0019] In step S1, the adhesive is one of PAN, PVP, PMMA, or PVA.

[0020] In step S1, the pore-expanding agent is one of KHCO3, NaHCO3, K2CO3, and Na2CO3.

[0021] The solvent in step S1 is one of deionized water, anhydrous ethanol, and DMF.

[0022] When the adhesive is PAN or PMMA, the solvent is anhydrous ethanol or DMF.

[0023] In step S3, the ammonia atmosphere is a mixture of ammonia and nitrogen with a volume fraction of 0.01-0.5%.

[0024] The supported aluminum-based catalyst is an aluminum-based catalyst supported with an active metal, and the supported aluminum-based catalyst is prepared by the following method:

[0025] An aluminum-based oxide precursor and an active metal salt precursor are added to deionized water and stirred to form a suspension A. Then, ammonia water is added to suspension A and stirred to obtain suspension B. Suspension B is then placed in a hydrothermal reactor and subjected to hydrothermal reaction at 105-140℃ for 8-24 hours to obtain suspension C. The solid obtained after filtering suspension C is dried at 85-105℃ for 9-16 hours to obtain a solid. Finally, the dried solid is calcined at 450-850℃ for 0.5-4 hours to obtain a supported aluminum-based catalyst.

[0026] The mass ratio of the active metal salt precursor to the aluminum-based oxide precursor is 5~80:100; the amount of ammonia added is the amount required to bring the pH of suspension B to 7.5~8.5.

[0027] The aluminum-based oxide precursor is one of Al2O3, ZnAlOx, CeAlOx, and CuAlOx, and the active metal salt precursor is one or more of the active metal soluble salts, wherein the active metal is one or more of Fe, Cu, Ni, Co, Zr, La, or Ce.

[0028] A bifunctional aluminum-based desulfurizer is prepared using the above-mentioned method for preparing bifunctional aluminum-based desulfurizers; the surface of the bifunctional aluminum-based desulfurizer has alkaline activation sites, oxygen vacancy sites and active metal-nitrogen bonds.

[0029] The beneficial effects of this invention are as follows:

[0030] (1) The bifunctional aluminum-based desulfurizer of the present invention catalytically hydrolyzes COS into H2S through the active metal oxides, alkaline activation sites and metal-nitrogen bonds formed by nitrogen doping on the surface of the desulfurizer. Under the action of the active oxygen groups on the surface of the desulfurizer, H2S is selectively oxidized into elemental sulfur and H2S is avoided from being over-oxidized into sulfate species. The COS removal efficiency reaches 100% at room temperature ~180℃ and atmospheric pressure ~8.0MPa, and the purified gas does not contain H2S. It can simultaneously and deeply remove COS and H2S, and has high stability and anti-sulfur poisoning performance.

[0031] (2) The bifunctional aluminum-based desulfurizer of the present invention simultaneously applies alkali modification and nitrogen doping to the molded desulfurizer, achieving simultaneous improvement in desulfurization performance and mechanical properties. In the preparation process of conventional desulfurization materials, molding is usually carried out first, followed by modification, which leads to the destruction of the structure and mechanical stability of the desulfurization material; while modification is carried out first, followed by molding, which leads to a significant reduction in the desulfurization performance of the desulfurization material. The present invention balances desulfurization performance and mechanical properties by simultaneously performing alkali modification during the molding process and improving the desulfurizer performance through subsequent nitrogen doping, which is conducive to realizing industrial application. Alkali metals can enhance the adsorption capacity of organic sulfur and hydrolysis product H2S, while promoting the dissociation of H2O molecules into hydroxyl groups on the catalyst surface, providing favorable conditions for the smooth progress of the hydrolysis reaction. Nitrogen doping can construct oxygen defect vacancies and metal-nitrogen bonds. The synergistic effect of the two can regulate the type of surface oxygen species, significantly improve the efficiency of H2S being selectively oxidized to elemental sulfur by surface oxygen species, and reduce the probability of metal oxides being converted into sulfides by H2S, thereby extending the catalyst's service life and improving its resistance to sulfur poisoning. The synergistic effect of binders and binding aids improves the mechanical properties of the desulfurizer, and the pore-expanding agent avoids the clogging effect of alkali modifiers on the pore structure during the molding process, while also playing a secondary pore-expanding role.

[0032] (3) The preparation method of the bifunctional aluminum-based desulfurizer of the present invention is green, simple, and easy to industrialize. The present invention uses ZnAlOx as a support and inexpensive metal salts as precursors, and prepares a supported catalyst through co-precipitation, calcination, alkali modification, and ammonia calcination processes. Compared with catalysts prepared using hydrotalcite-like or titanium-based supports, this process has a shorter preparation cycle and lower production cost; compared with conventional impregnation and sol-gel methods, this process can precisely control the catalyst particle size and surface metal dispersion. The prepared desulfurizer has excellent catalytic stability and high desulfurization efficiency, and has broad industrial application prospects. Attached Figure Description

[0033] Figure 1 The COS removal efficiency and H2S concentration in the purified gas of the desulfurizing agents prepared in Examples 1-7 and Comparative Examples 1-5 of this invention are shown. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0035] In the following examples and comparative examples, the desulfurization performance of the desulfurizing agent can be represented by the COS removal rate and the H2S concentration in the purified gas, and the mechanical properties of the desulfurizing agent can be represented by the lateral pressure resistance.

[0036] Example 1

[0037] This invention provides a method for preparing a bifunctional aluminum-based desulfurizer, specifically comprising the following steps:

[0038] (1) Add 2g Al2O3 and 0.1g Cu(NO3)2 to deionized water and stir to form suspension A. Then add ammonia water (mass concentration of 25%, the same below) to suspension A and continue stirring. Adjust the pH to 7.7 to obtain suspension B. Then place suspension B in a hydrothermal reactor and perform hydrothermal reaction at 105℃ for 12h to obtain suspension C. Then filter the solid of suspension C and dry it at 85℃ for 12h to obtain solid. Finally, calcine the dried solid at 750℃ for 3.5h to obtain supported aluminum-based catalyst.

[0039] (2) Mix 2g of supported aluminum-based catalyst, 0.02g of NaOH and 0.7g of deionized water and knead for 60min. During the kneading process, add 0.38g of boehmite, 0.038g of aluminum nitrate, 0.02g of PVP and 0.1g of NaHCO3 in sequence to obtain a mixed kneading material. Then, extrude the mixed kneading material through an extrusion molding machine to obtain a columnar aluminum-based catalyst precursor. After vacuum drying at 65℃ for 6h, obtain the shaped aluminum-based catalyst precursor.

[0040] (3) The shaped aluminum-based catalyst precursor was placed in a tube furnace and calcined at 500°C for 60 min in an air atmosphere.

[0041] (4) The air-calcined aluminum-based catalyst precursor is placed in a mixture of ammonia and nitrogen with a volume fraction of 0.01% (flow rate of 40 mL / min) and calcined at 500°C for 240 min to obtain bifunctional aluminum-based desulfurizer I.

[0042] Example 2

[0043] This invention provides a method for preparing a bifunctional aluminum-based desulfurizer, specifically comprising the following steps:

[0044] (1) Add 2g ZnAlOx and 1.2g Ni(NO3)2 to deionized water and stir to form suspension A. Then add ammonia water to suspension A and continue stirring to adjust the pH to 7.5 to obtain suspension B. Then place suspension B in a hydrothermal reactor and perform a hydrothermal reaction at 115℃ for 16h to obtain suspension C. Then filter the solid of suspension C and dry it at 105℃ for 9h to obtain solid. Finally, calcine the dried solid at 850℃ for 2h to obtain a supported aluminum-based catalyst.

[0045] (2) 2g of supported aluminum-based catalyst, 0.2g of KOH and 1g of DMF were mixed and kneaded for 90min. During the kneading process, 0.46g of boehmite, 0.04g of aluminum nitrate, 0.3g of PAN and 0.08g of KHCO3 were added in sequence to obtain a mixed kneading material. The mixed kneading material was then extruded through an extrusion molding machine to obtain a columnar aluminum-based catalyst precursor. After vacuum drying at 90℃ for 4h, the shaped aluminum-based catalyst precursor was obtained.

[0046] (3) The shaped aluminum-based catalyst precursor was placed in a tube furnace and calcined at 700°C for 120 min in an air atmosphere.

[0047] (4) The air-calcined shaped aluminum-based catalyst precursor is placed under a mixture of ammonia and nitrogen with a volume fraction of 0.02% (flow rate of 40 mL / min) and calcined at 700°C for 50 min to obtain bifunctional aluminum-based desulfurizer II.

[0048] Example 3

[0049] This invention provides a method for preparing a bifunctional aluminum-based desulfurizer, specifically comprising the following steps:

[0050] (1) 2g CeAlOx and 1.6g Fe(NO3)3 were added to deionized water and stirred to form suspension A. Then ammonia water was added to suspension A and stirred to adjust the pH to 8.2 to obtain suspension B. Suspension B was then placed in a hydrothermal reactor and subjected to hydrothermal reaction at 130℃ for 24h to obtain suspension C. The solid after filtering suspension C was dried at 90℃ for 16h to obtain solid. Finally, the dried solid was calcined at 450℃ for 2.5h to obtain supported aluminum-based catalyst.

[0051] (2) 2g of supported aluminum-based catalyst, 0.4g of KHCO3 and 1.3g of anhydrous ethanol were mixed and kneaded for 180min. During the kneading process, 0.095g of boehmite, 0.005g of aluminum nitrate, 0.1g of PMMA and 0.02g of K2CO3 were added in sequence to obtain a mixed kneading material. The mixed kneading material was then extruded through an extrusion molding machine to obtain a columnar aluminum-based catalyst precursor. After vacuum drying at 95℃ for 3h, the shaped aluminum-based catalyst precursor was obtained.

[0052] (3) The shaped aluminum-based catalyst precursor was placed in a tube furnace and calcined at 850°C for 90 min in an air atmosphere.

[0053] (4) The air-calcined shaped aluminum-based catalyst precursor is placed in a mixture of ammonia and nitrogen with a volume fraction of 0.5% (flow rate of 40 mL / min) and calcined at 450°C for 80 min to obtain bifunctional aluminum-based desulfurizer III.

[0054] Example 4

[0055] This invention provides a method for preparing a bifunctional aluminum-based desulfurizer, specifically comprising the following steps:

[0056] (1) Add 2g CuAlOx and 0.8g Ce(NO3)3 to deionized water and stir to form suspension A. Then add ammonia water to suspension A and continue stirring to adjust the pH to 8.5 to obtain suspension B. Then place suspension B in a hydrothermal reactor and perform a hydrothermal reaction at 120℃ for 18h to obtain suspension C. Then filter the solid of suspension C and dry it at 100℃ for 14h to obtain solid. Finally, calcine the dried solid at 550℃ for 0.5h to obtain a supported aluminum-based catalyst.

[0057] (2) 2g of supported aluminum-based catalyst, 0.15g of NaHCO3 and 0.75g of deionized water were mixed and kneaded for 120min. During the kneading process, 0.3g of boehmite, 0.003g of aluminum nitrate, 0.05g of PVA and 0.05g of Na2CO3 were added in sequence to obtain a mixed kneading material. The mixed kneading material was then extruded through an extrusion molding machine to obtain a columnar aluminum-based catalyst precursor. After vacuum drying at 70℃ for 0.5h, the shaped aluminum-based catalyst precursor was obtained.

[0058] (3) The shaped aluminum-based catalyst precursor was placed in a tube furnace and calcined at 600°C for 30 min in an air atmosphere.

[0059] (4) The air-calcined aluminum-based catalyst precursor is placed in a mixture of ammonia and nitrogen with a volume fraction of 0.25% (flow rate of 40 mL / min) and calcined at 300°C for 30 min to obtain bifunctional aluminum-based desulfurizer IV.

[0060] Example 5

[0061] This invention provides a method for preparing a bifunctional aluminum-based desulfurizer, specifically comprising the following steps:

[0062] (1) Add 2g ZnAlOx and 1g La(NO3)3 to deionized water and stir to form suspension A. Then add ammonia water to suspension A and continue stirring to adjust the pH to 7.9 to obtain suspension B. Then place suspension B in a hydrothermal reactor and perform hydrothermal reaction at 140℃ for 8h to obtain suspension C. Then filter the solid of suspension C and dry it at 95℃ for 15h to obtain solid. Finally, calcine the dried solid at 600℃ for 1.5h to obtain supported aluminum-based catalyst.

[0063] (2) Mix 2g of supported aluminum-based catalyst, 0.2g of KOH, 0.1g of K2CO3 and 1.1g of DMF and knead for 150min. During the kneading process, add 0.4g of boehmite, 0.02g of aluminum nitrate, 0.04g of PMMA and 0.06g of KHCO3 in sequence to obtain a mixed kneading material. Then, extrude the mixed kneading material through an extrusion molding machine to obtain a columnar aluminum-based catalyst precursor. After vacuum drying at 60℃ for 2h, obtain the shaped aluminum-based catalyst precursor.

[0064] (3) The shaped aluminum-based catalyst precursor was placed in a tube furnace and calcined at 900°C for 45 min in an air atmosphere.

[0065] (4) The air-calcined shaped aluminum-based catalyst precursor is placed in a mixture of ammonia and nitrogen with a volume fraction of 0.06% (flow rate of 40 mL / min) and calcined at 600°C for 120 min to obtain bifunctional aluminum-based desulfurizer V.

[0066] Example 6

[0067] This invention provides a method for preparing a bifunctional aluminum-based desulfurizer, specifically comprising the following steps:

[0068] (1) 2g Al2O3, 0.8g Co(NO3)2 and 0.5g Ce(NO3)3 were added to deionized water and stirred to form suspension A. Then ammonia water was added to suspension A and stirred to adjust the pH to 8.0 to obtain suspension B. Suspension B was then placed in a hydrothermal reactor and hydrothermally reacted at 125℃ for 15h to obtain suspension C. The solid after filtering suspension C was dried at 90℃ for 10h to obtain solid. Finally, the dried solid was calcined at 500℃ for 3h to obtain supported aluminum-based catalyst.

[0069] (2) Mix 2g of supported aluminum-based catalyst, 0.12g of NaOH, 0.08g of NaHCO3 and 0.95g of deionized water and knead for 75min. During the kneading process, add 0.3g of boehmite, 0.009g of aluminum nitrate, 0.15g of PVA and 0.08g of Na2CO3 in sequence to obtain a mixed kneading material. Then, extrude the mixed kneading material through an extrusion molding machine to obtain a columnar aluminum-based catalyst precursor. After vacuum drying at 80℃ for 2.5h, obtain the shaped aluminum-based catalyst precursor.

[0070] (3) The shaped aluminum-based catalyst precursor was placed in a tube furnace and calcined at 550°C for 70 min in an air atmosphere.

[0071] (4) The air-calcined shaped aluminum-based catalyst precursor is placed in a mixture of ammonia and nitrogen with a volume fraction of 0.2% (flow rate of 40 mL / min) and calcined at 550°C for 150 min to obtain bifunctional aluminum-based desulfurizer VI.

[0072] Example 7

[0073] This invention provides a method for preparing a bifunctional aluminum-based desulfurizer, specifically comprising the following steps:

[0074] (1) 2g Al2O3, 0.4g ZrOCl2 and 1.2g La(NO3)3 were added to deionized water and stirred to form suspension A. Then ammonia water was added to suspension A and stirred to adjust the pH to 8.4 to obtain suspension B. Suspension B was placed in a hydrothermal reactor and hydrothermally reacted at 110℃ for 20h to obtain suspension C. The solid after filtering suspension C was dried at 105℃ for 13h to obtain solid. Finally, the dried solid was calcined at 800℃ for 4h to obtain supported aluminum-based catalyst.

[0075] (2) 2g of supported aluminum-based catalyst, 0.1g of Na2CO3 and 0.7g of DMF were mixed and kneaded for 115min. During the kneading process, 0.15g of boehmite, 0.005g of aluminum nitrate, 0.2g of PAN and 0.03g of NaHCO3 were added in sequence to obtain a mixed kneading material. The mixed kneading material was then extruded through an extrusion molding machine to obtain a columnar aluminum-based catalyst precursor. After vacuum drying at 85℃ for 1h, the shaped aluminum-based catalyst precursor was obtained.

[0076] (3) The shaped aluminum-based catalyst precursor was placed in a tube furnace and calcined at 850°C for 75 min in an air atmosphere.

[0077] (4) The air-calcined shaped aluminum-based catalyst precursor is placed in a mixture of ammonia and nitrogen with a volume fraction of 0.35% (flow rate of 40 mL / min) and calcined at 550°C for 180 min to obtain bifunctional aluminum-based desulfurizer VII.

[0078] Comparative Example 1 (without adhesive)

[0079] Specifically, the steps include the following:

[0080] (1) Add 2g Al2O3 and 0.1g Cu(NO3)2 to deionized water and stir to form suspension A. Then add ammonia water (mass concentration of 25%, the same below) to suspension A and continue stirring. Adjust the pH to 7.7 to obtain suspension B. Then place suspension B in a hydrothermal reactor and perform hydrothermal reaction at 105℃ for 12h to obtain suspension C. Then filter the solid of suspension C and dry it at 85℃ for 12h to obtain solid. Finally, calcine the dried solid at 750℃ for 3.5h to obtain supported aluminum-based catalyst.

[0081] (2) Mix 2g of supported aluminum-based catalyst, 0.02g of NaOH and 0.7g of deionized water and knead for 60min. During the kneading process, add 0.02g of PVP and 0.1g of NaHCO3 in sequence to obtain a mixed kneading material. Then, extrude the mixed kneading material through an extrusion molding machine to obtain a columnar aluminum-based catalyst precursor. After vacuum drying at 65℃ for 6h, obtain the shaped aluminum-based catalyst precursor.

[0082] (3) The shaped aluminum-based catalyst precursor was placed in a tube furnace and calcined at 500°C for 60 min in an air atmosphere, and then calcined at 500°C for 240 min in a mixed gas of ammonia and nitrogen with a volume fraction of 0.01% (flow rate of 40 mL / min) to obtain the comparative catalyst D1.

[0083] Comparative Example 2 (without adhesive additives)

[0084] Specifically, the steps include the following:

[0085] (1) Add 2g Al2O3 and 0.1g Cu(NO3)2 to deionized water and stir to form suspension A. Then add ammonia water (mass concentration of 25%, the same below) to suspension A and continue stirring. Adjust the pH to 7.7 to obtain suspension B. Then place suspension B in a hydrothermal reactor and perform hydrothermal reaction at 105℃ for 12h to obtain suspension C. Then filter the solid of suspension C and dry it at 85℃ for 12h to obtain solid. Finally, calcine the dried solid at 750℃ for 3.5h to obtain supported aluminum-based catalyst.

[0086] (2) Mix 2g of supported aluminum-based catalyst, 0.02g of NaOH and 0.7g of deionized water and knead for 60min. During the kneading process, add 0.38g of boehmite, 0.038g of aluminum nitrate and 0.1g of NaHCO3 in sequence to obtain a mixed kneading material. Then, extrude the mixed kneading material through an extrusion molding machine to obtain a columnar aluminum-based catalyst precursor. After vacuum drying at 65℃ for 6h, obtain the shaped aluminum-based catalyst precursor.

[0087] (3) The shaped aluminum-based catalyst precursor was placed in a tube furnace and calcined at 500°C for 60 min in an air atmosphere, and then calcined at 500°C for 240 min in a mixed gas of ammonia and nitrogen with a volume fraction of 0.01% (flow rate of 40 mL / min) to obtain the comparative catalyst D2.

[0088] Comparative Example 3 (without pore expander)

[0089] Specifically, the steps include the following:

[0090] (1) Add 2g Al2O3 and 0.1g Cu(NO3)2 to deionized water and stir to form suspension A. Then add ammonia water (mass concentration of 25%, the same below) to suspension A and continue stirring. Adjust the pH to 7.7 to obtain suspension B. Then place suspension B in a hydrothermal reactor and perform hydrothermal reaction at 105℃ for 12h to obtain suspension C. Then filter the solid of suspension C and dry it at 85℃ for 12h to obtain solid. Finally, calcine the dried solid at 750℃ for 3.5h to obtain supported aluminum-based catalyst.

[0091] (2) Mix 2g of supported aluminum-based catalyst, 0.02g of NaOH and 0.7g of deionized water and knead for 60min. During the kneading process, add 0.38g of boehmite, 0.038g of aluminum nitrate and 0.02g of PVP in sequence to obtain a mixed kneading material. Then, extrude the mixed kneading material through an extrusion molding machine to obtain a columnar aluminum-based catalyst precursor. After vacuum drying at 65℃ for 6h, obtain the shaped aluminum-based catalyst precursor.

[0092] (3) The shaped aluminum-based catalyst precursor was placed in a tube furnace and calcined at 500°C for 60 min in an air atmosphere, and then calcined at 500°C for 240 min in a mixed gas of ammonia and nitrogen with a volume fraction of 0.01% (flow rate of 40 mL / min) to obtain the comparative catalyst D3.

[0093] Comparative Example 4 (without air roasting)

[0094] Specifically, the steps include the following:

[0095] (1) Add 2g Al2O3 and 0.1g Cu(NO3)2 to deionized water and stir to form suspension A. Then add ammonia water (mass concentration of 25%, the same below) to suspension A and continue stirring. Adjust the pH to 7.7 to obtain suspension B. Then place suspension B in a hydrothermal reactor and perform hydrothermal reaction at 105℃ for 12h to obtain suspension C. Then filter the solid of suspension C and dry it at 85℃ for 12h to obtain solid. Finally, calcine the dried solid at 750℃ for 3.5h to obtain supported aluminum-based catalyst.

[0096] (2) Mix 2g of supported aluminum-based catalyst, 0.02g of NaOH and 0.7g of deionized water and knead for 60min. During the kneading process, add 0.38g of boehmite, 0.038g of aluminum nitrate, 0.02g of PVP and 0.1g of NaHCO3 in sequence to obtain a mixed kneading material. Then, extrude the mixed kneading material through an extrusion molding machine to obtain a columnar aluminum-based catalyst precursor. After vacuum drying at 65℃ for 6h, obtain the shaped aluminum-based catalyst precursor.

[0097] (3) The shaped aluminum-based catalyst precursor was placed in a tube furnace and calcined at 500°C for 240 min under a mixture of ammonia and nitrogen with a volume fraction of 0.01% (flow rate of 40 mL / min) to obtain the comparative catalyst D4.

[0098] Comparative Example 5 (without ammonia roasting)

[0099] Specifically, the steps include the following:

[0100] (1) Add 2g Al2O3 and 0.1g Cu(NO3)2 to deionized water and stir to form suspension A. Then add ammonia water (mass concentration of 25%, the same below) to suspension A and continue stirring. Adjust the pH to 7.7 to obtain suspension B. Then place suspension B in a hydrothermal reactor and perform hydrothermal reaction at 105℃ for 12h to obtain suspension C. Then filter the solid of suspension C and dry it at 85℃ for 12h to obtain solid. Finally, calcine the dried solid at 750℃ for 3.5h to obtain supported aluminum-based catalyst.

[0101] (2) Mix 2g of supported aluminum-based catalyst, 0.02g of NaOH and 0.7g of deionized water and knead for 60min. During the kneading process, add 0.38g of boehmite, 0.038g of aluminum nitrate, 0.02g of PVP and 0.1g of NaHCO3 in sequence to obtain a mixed kneading material. Then, extrude the mixed kneading material through an extrusion molding machine to obtain a columnar aluminum-based catalyst precursor. After vacuum drying at 65℃ for 6h, obtain the shaped aluminum-based catalyst precursor.

[0102] (3) The shaped aluminum-based catalyst precursor was placed in a tube furnace and calcined at 500°C for 60 min in an air atmosphere to obtain the comparative catalyst D5.

[0103] The activity test of the desulfurizing agent was carried out in a fixed-bed quartz reactor under the following conditions: COS concentration 300 ppm, space velocity 10000 h⁻¹. -1 The reaction temperature was 70℃. The COS removal rate and H2S concentration in the purified gas of the desulfurizing agents prepared in Examples 1-7 and Comparative Examples 1-5 are shown in the table below. Figure 1 The corresponding removal times for 100% COS and 100% H2S are shown in Table 1.

[0104] Table 1. 100% desulfurization time of the desulfurizing agents prepared in Examples 1-7 and Comparative Examples 1-5

[0105]

[0106] From Table 1 and Figure 1 As can be seen from the above, the desulfurization performance of the desulfurizers prepared in Examples 1-7 is far superior to that of Comparative Examples 1-5. Under the above reaction conditions, they can achieve 100% desulfurization efficiency, which indicates that the bifunctional aluminum-based desulfurizer prepared in this invention has a significant effect on the removal of COS and H2S.

[0107] The results of the lateral pressure resistance of the desulfurizing agents prepared in Examples 1-7 and Comparative Examples 1-5 are shown in Table 2.

[0108] Table 2. Lateral compressive strength of the desulfurizing agents prepared in Examples 1-7 and Comparative Examples 1-5

[0109]

[0110] As can be seen from Table 2, the mechanical strength of the desulfurizer prepared by this invention also meets the requirements of actual industrial applications (≥40N / cm).

[0111] The bifunctional aluminum-based desulfurizer prepared by this invention comprises an aluminum-based oxide carrier, an active metal oxide component, basic groups, and metal-nitrogen bonds formed by nitrogen doping. This invention utilizes a hydrothermal synthesis method to load the active metal onto the aluminum-based oxide carrier, followed by alkali modification, kneading, air calcination, and ammonia calcination processes to prepare the desulfurizer. The desulfurizer prepared by this method possesses abundant basic and metal active sites, exhibiting strong adsorption and catalytic capabilities. It can not only catalytically hydrolyze COS to H2S at low temperatures but also selectively oxidize H2S to elemental sulfur through the interaction of oxygen vacancies and metal-nitrogen bonds on the desulfurizer surface, achieving deep and precise removal of organic sulfur and its hydrolysis products. The synergistic effect of multiple components on the desulfurizer surface enhances its resistance to water and sulfur poisoning, improving its service life and desulfurization efficiency. The synergistic effect of the binder and bonding aid improves the mechanical properties of the desulfurizer, while the pore-expanding agent prevents the alkali modifier from blocking the pore structure during molding and simultaneously provides secondary pore expansion.

[0112] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention. The above embodiments are provided only for the purpose of describing the present invention and are not intended to limit the present invention. Parts not described in detail in this specification are well-known in the art and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. All equivalent substitutions and modifications made without departing from the spirit and principle of the present invention should be covered within the scope of the present invention.

Claims

1. A method for preparing a bifunctional aluminum-based desulfurizing agent, characterized in that, Includes the following steps: S1: The supported aluminum-based catalyst, alkali modifier and solvent are mixed and kneaded. During the kneading process, a binder, a binding aid and a pore-expanding agent are added in sequence to obtain a mixed kneaded material. The mixed kneaded material is shaped to obtain a columnar aluminum-based catalyst precursor. A shaped aluminum-based catalyst precursor was obtained by vacuum drying of the columnar aluminum-based catalyst precursor; wherein the mass ratio of the supported aluminum-based catalyst, the alkali modifier and the solvent was 100:1~20:35~65; and the mass ratio of the supported aluminum-based catalyst, the binder, the binding aid and the pore expander was 100:5~25:1~15:1~5. S2: The shaped aluminum-based catalyst precursor is calcined in air atmosphere; The air calcination temperature is 500~900℃, and the air calcination time is 30~120min; S3: The air-calcined shaped aluminum-based catalyst precursor is calcined in an ammonia atmosphere to obtain a bifunctional aluminum-based desulfurizer; the ammonia calcination temperature is 300~700℃ and the ammonia calcination time is 30~240min.

2. The preparation method of the bifunctional aluminum-based desulfurizer according to claim 1, characterized in that, The vacuum drying temperature in step S1 is 60~95℃, and the vacuum drying time is 0.5~6h; the alkali modifier is one or more of KOH, NaOH, KHCO3, NaHCO3, K2CO3, and Na2CO3.

3. The preparation method of the bifunctional aluminum-based desulfurizer according to claim 1, characterized in that, The binder in step S1 is a mixture of boehmite and aluminum nitrate, with a mass ratio of boehmite to aluminum nitrate of 100:1~10.

4. The preparation method of the bifunctional aluminum-based desulfurizer according to claim 1, characterized in that, The adhesive in step S1 is one of PAN, PVP, PMMA, or PVA.

5. The preparation method of the bifunctional aluminum-based desulfurizer according to claim 1, characterized in that, The pore-expanding agent in step S1 is one of KHCO3, NaHCO3, K2CO3, and Na2CO3.

6. The preparation method of the bifunctional aluminum-based desulfurizer according to claim 1, characterized in that, The solvent in step S1 is one of deionized water, anhydrous ethanol, or DMF.

7. The preparation method of the bifunctional aluminum-based desulfurizer according to claim 6, characterized in that, When the adhesive is PAN or PMMA, the solvent is anhydrous ethanol or DMF.

8. The preparation method of the bifunctional aluminum-based desulfurizer according to claim 1, characterized in that, The ammonia atmosphere in step S3 is a mixture of ammonia and nitrogen with a volume fraction of 0.01~0.5%.

9. The method for preparing the bifunctional aluminum-based desulfurizer according to any one of claims 1 to 8, characterized in that, The supported aluminum-based catalyst is an aluminum-based catalyst supported with an active metal, and the supported aluminum-based catalyst is prepared by the following method: An aluminum-based oxide precursor and an active metal salt precursor are added to deionized water and stirred to form a suspension A. Then, ammonia water is added to suspension A and stirred to obtain suspension B. Suspension B is then placed in a hydrothermal reactor and subjected to hydrothermal reaction at 105-140℃ for 8-24 hours to obtain suspension C. The solid obtained after filtering suspension C is dried at 85-105℃ for 9-16 hours to obtain a solid. Finally, the dried solid is calcined at 450-850℃ for 0.5-4 hours to obtain a supported aluminum-based catalyst. The mass ratio of the active metal salt precursor to the aluminum-based oxide precursor is 5~80:100; the amount of ammonia added is the amount required to bring the pH of suspension B to 7.5~8.

5. The aluminum-based oxide precursor is one of Al2O3, ZnAlOx, CeAlOx, and CuAlOx, and the active metal salt precursor is one or more of the active metal soluble salts, wherein the active metal is one or more of Fe, Cu, Ni, Co, Zr, La, or Ce.

10. A bifunctional aluminum-based desulfurizer, characterized in that, The bifunctional aluminum-based desulfurizer is prepared by the preparation method of any one of claims 1 to 9; the surface of the bifunctional aluminum-based desulfurizer has alkaline activation sites, oxygen vacancy sites and active metal-nitrogen bonds.

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