High-sulfur capacity hierarchical porous structure desulfurizer and preparation method thereof

Abstract

The application discloses a high-sulfur capacity hierarchical porous structure desulfurizer and a preparation method thereof, and belongs to the technical field of gas purification materials. The hierarchical porous alumina carrier is obtained by an in-situ hydrothermal growth method, and then the active components and catalytic additives, such as Zn, Cu, Ce, Mg, La and metal oxides, are highly dispersedly loaded in the hierarchical pores by using a complex co-precipitation method, and the desulfurizer is obtained after being dried and formed by calcination. The application has the advantages that the hierarchical porous structure greatly promotes the reaction mass transfer and provides abundant active site loading space; and the synergistic effect of the multiple additives effectively improves the sulfuration reaction activity and the anti-sintering capacity. The desulfurizer prepared by the method has excellent performances such as high sulfur capacity, fast reaction speed, high mechanical strength and good stability, and is particularly suitable for high-precision deep removal of hydrogen sulfide in gas such as synthetic gas and natural gas.

Description

Technical Field

[0001] This invention belongs to the field of gas purification technology and relates to a method for preparing a high-sulfur-capacity desulfurizer with a hierarchical porous structure by combining in-situ hydrothermal treatment, impregnation and co-precipitation. Specifically, it is a high-sulfur-capacity hierarchical porous desulfurizer and its preparation method. Background Technology

[0002] Hydrogen sulfide is commonly found in natural gas, syngas, and refinery tail gas. It not only corrodes equipment and pipelines but also poisons catalysts and pollutes the environment. Therefore, developing high-performance desulfurizing agents is of great significance.

[0003] Existing zinc oxide desulfurizers generally suffer from problems such as low sulfur capacity, high diffusion mass transfer resistance, insufficient dispersion of active components, and low utilization rate. The main reason is that the pore structure of traditional desulfurizers is often dominated by micropores, and their distribution is uniform, which is not conducive to the internal diffusion of reactant molecules. As a result, the desulfurization reaction mostly occurs on the surface of the desulfurizer, and the internal active components cannot be fully utilized.

[0004] Currently, patent publication number "CN 120054657 A" discloses a zinc oxide-cerium oxide desulfurizing agent, which uses ammonium carbonate as a pore-forming agent and polyferric sulfate as a settling agent to construct a large- and small-pore composite structure to improve sulfur capacity at high space velocities. However, this method still relies primarily on precipitation, and the dispersibility of its active components is limited by the precipitation process. Furthermore, it does not address the fine construction of multi-level pores in the carrier itself. Patent publication number "CN 117563413 A" focuses on low-temperature flue gas desulfurization, improving desulfurization efficiency and stability at room temperature by introducing SBA-15 mesoporous molecular sieves and complex modified bentonite agents and stabilizing agents. This approach has complex components, a lengthy preparation process, and high costs. Moreover, its high strength, high sulfur capacity, and high space velocity performance are not design priorities, making it difficult to apply to high-pressure, high-space-velocity industrial raw gas purification scenarios. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a method for preparing a desulfurizing agent that is simple to prepare, has high sulfur capacity, good mechanical strength, and highly dispersed active components. The desulfurizing agent prepared by this method is particularly suitable for the high-precision deep removal of hydrogen sulfide from gases such as syngas and natural gas.

[0006] To achieve the above-mentioned objectives, the specific technical solution of the present invention is as follows:

[0007] A high-sulfur-capacity hierarchical porous desulfurizer is disclosed. The desulfurizer uses macroporous alumina microspheres as the core framework, and nanosheet structures are grown on the surface of the microspheres to form interconnected macroporous-mesoporous hierarchical channels. The active component ZnO and the auxiliary agents CuO, CeO2, MgO and La2O3 are highly dispersed in the hierarchical channels in the form of nanocrystals.

[0008] A method for preparing a high-sulfur-capacity hierarchical porous desulfurizer involves in-situ hydrothermal modification of macroporous alumina to construct a nanostructure on its surface, forming a hierarchical porous carrier that combines a macroporous framework and a mesoporous shell, and then loading the active components through impregnation and complexation-coprecipitation methods.

[0009] Specifically, the following steps are included:

[0010] (1) Carrier pretreatment: The macroporous alumina microspheres were soaked in dilute nitric acid solution, washed until neutral, and dried to obtain the acid-washed macroporous alumina carrier;

[0011] (2) Preparation and adjustment of aluminum sol: Dissolve aluminum nitrate nonahydrate in deionized water, stir to form a clear solution, and then adjust the pH value with alkaline solution to obtain aluminum sol;

[0012] (3) Growth in the original hot water: The acid-washed alumina carrier obtained in step (1) is mixed with the adjusted aluminum sol obtained in step (2) and placed in a hydrothermal reactor for hydrothermal reaction. After the reaction is completed, the product is cooled, washed and dried to obtain a graded porous carrier precursor.

[0013] (4) The graded porous carrier precursor obtained in step (3) is placed in a muffle furnace for calcination to obtain a graded porous carrier.

[0014] (5) Preparation of mixed salt-complexing agent solution: Dissolve citric acid and nitrates of zinc, copper, cerium, magnesium and lanthanum in deionized water to form a mixed salt solution.

[0015] (6) Impregnation and coprecipitation: The graded porous carrier precursor obtained in step (3) is impregnated in the mixed salt solution obtained in step (4), and then a sodium carbonate precipitant solution is added dropwise to the system under stirring to carry out a coprecipitation reaction, followed by aging;

[0016] (7) Post-processing: The product aged in step (5) is washed, dried and calcined;

[0017] (8) Molding: After roasting, the material is mixed with binder and water, then dried and roasted to obtain the finished desulfurizer.

[0018] Furthermore, in step (2) of the preparation method of a high sulfur capacity graded porous structure desulfurizer, the alkaline solution is ammonia water, urea solution or sodium hydroxide solution; its pH value is adjusted to 4.5 to 5.5, preferably adjusted to 5.0.

[0019] Furthermore, in step (3) of the preparation method of a high sulfur capacity graded porous structure desulfurizer, the temperature of the hydrothermal reaction is 120-160℃, the reaction time is 8-12 hours, and the preferred temperature is 140℃.

[0020] Furthermore, in step (4) of the preparation method of a high sulfur capacity graded porous structure desulfurizer, the calcination process is as follows: the temperature is increased to 500-600℃ at a rate of 1-2℃ / min and kept constant for 3-5 hours.

[0021] Furthermore, in step (5) of the preparation method of a high sulfur capacity graded porous structure desulfurizer, the molar percentage of each metal element is: Zn 60-80%, Cu 5-15%, Ce 5-10%, Mg 2-8%, La 2-8%; the ratio of the amount of citric acid added to the total molar amount of metal elements is (1.0-1.5):1.

[0022] Furthermore, in step (6) of the preparation method of a high sulfur capacity graded porous structure desulfurizer, the temperature of the coprecipitation reaction is 60-70℃, the pH value is controlled at 7.5-8.5, and the aging time is 1-3 hours.

[0023] Furthermore, in step (7) of the preparation method of a high sulfur capacity graded porous structure desulfurizer, the calcination procedure is as follows: the temperature is increased to 400-500℃ at a rate of 2-5℃ / min and kept constant for 3-5 hours.

[0024] Furthermore, in step 8 of the preparation method of a high-sulfur-capacity graded porous desulfurizer, the binder is guar gum powder, and its addition amount is in a mass ratio of 0.05-0.1:1 to the calcined material. The calcination procedure is as follows: heating to 450℃ at a rate of 2℃ / min and calcining for 2 hours.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] (i) This invention directly grows a mesoporous shell on commercial macroporous alumina using an in-situ hydrothermal method, successfully constructing a hierarchical pore structure of "macropore-mesopore", resulting in rapid mass transfer and highly dispersed active sites, which greatly reduces internal diffusion resistance and improves the mass transfer efficiency and high sulfur capacity of the reactant gas.

[0027] (ii) The preparation method has a clear process, mild conditions, and readily available raw materials. It does not require complex templates or expensive equipment and has good prospects for industrial production.

[0028] (III) The desulfurizing agent prepared by the method of the present invention has excellent properties such as high sulfur capacity, fast reaction speed, high mechanical strength and good stability, and is suitable for removing hydrogen sulfide from natural gas, syngas, biogas or refinery gas. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] In this invention, some conventional operating equipment, devices and components have been omitted or only briefly described.

[0033] Unless otherwise specified in the examples, the conditions shall be performed according to the standard conditions or the conditions recommended by the manufacturer.

[0034] In this application, all percentages not explicitly stated represent volume percentage, i.e., v / v.

[0035] Example 1:

[0036] A method for preparing a high-sulfur-capacity graded porous desulfurizer includes the following steps:

[0037] Take 50g of macroporous alumina microspheres with an average pore size of 50nm, soak them in 500ml of 2wt% nitric acid solution for 2h, wash them with deionized water until the pH of the filtrate is 6-7, and dry them in an oven at 100℃ for 10h to obtain the acid-washed alumina carrier.

[0038] Weigh 56.3 g of Al(NO3)3·9H2O and dissolve it in 300 mL of deionized water. Stir magnetically to form a clear solution. Add dilute ammonia dropwise to adjust the pH to 5.0 to obtain aluminum sol.

[0039] The acid-washed alumina support was added to the alumina sol and transferred to a 500ml hydrothermal reactor. The reaction was carried out at 140℃ for 10h. After cooling and filtration, the mixture was washed three times with deionized water and dried in an oven at 100℃ for 10h to obtain a hierarchical porous support precursor.

[0040] The obtained hierarchical porous support precursor was placed in a muffle furnace and heated to 500℃ at a rate of 1-2℃ / min, and held at that temperature for 3.5 hours to obtain the hierarchical porous support.

[0041] Weigh out 34.68 g of citric acid, 31.24 g of Zn(NO3)2·6H2O, 2.90 g of Cu(NO3)2·3H2O, 5.21 g of Ce(NO3)3·6H2O, 2.69 g of Mg(NO3)2·6H2O, and 4.55 g of La(NO3)3·6H2O, and dissolve them in 400 ml of deionized water. Stir until clear to obtain a mixed salt solution.

[0042] Weigh 79.5g of anhydrous sodium carbonate and dissolve it in 500ml of distilled water, stirring until the solution is clear.

[0043] Adjust the water bath temperature to 65℃, pour the mixed salt solution into the water bath, and then add the graded porous carrier precursor to the salt solution for 2 hours of soaking. While continuously stirring, slowly add 1.5 mol / L Na₂CO₃ solution dropwise using a peristaltic pump to co-precipitate until the pH value in the water bath reaches 7.5-8.0, at which point precipitation is complete. Aging is then carried out at 65℃ with stirring for 2 hours.

[0044] The aged product was filtered and washed four times with distilled water at 60°C. After washing, it was placed in an oven and dried at 110°C for 12 hours.

[0045] The dried material was placed in a muffle furnace and heated to 450°C at a rate of 3°C / min for 4 hours. After cooling, it was removed.

[0046] Weigh 60g of the above powdered material, add 3.00g of guar gum powder, and slowly add deionized water to mix and knead until a uniform paste with good plasticity is formed. Then, use a twin-screw extruder to extrude the paste through a die with a 3.0 mm orifice to obtain cylindrical strips with a diameter of approximately 3 mm. Dry the obtained strips at 110℃ for 6 hours, and then calcine them in a muffle furnace at a temperature increased to 450℃ at 2℃ / min for 2 hours to obtain desulfurizer A.

[0047] Example 2:

[0048] A method for preparing a high-sulfur-capacity graded porous desulfurizer includes the following steps:

[0049] Take 50g of macroporous alumina microspheres with an average pore size of 50nm, soak them in 500ml of 2wt% nitric acid solution for 2h, wash them with deionized water until the pH of the filtrate is 6-7, and dry them in an oven at 100℃ for 10h to obtain the acid-washed alumina carrier.

[0050] Weigh 56.3 g of Al(NO3)3·9H2O and dissolve it in 300 mL of deionized water. Stir magnetically to form a clear solution. Add dilute ammonia dropwise to adjust the pH to 5.0 to obtain aluminum sol.

[0051] The acid-washed alumina support was added to the alumina sol and transferred to a 500ml hydrothermal reactor. The reaction was carried out at 140℃ for 10h. After cooling and filtration, the mixture was washed three times with deionized water and dried in an oven at 100℃ for 10h to obtain a hierarchical porous support precursor.

[0052] The obtained hierarchical porous support precursor was placed in a muffle furnace and heated to 500℃ at a rate of 1-2℃ / min, and held at that temperature for 3.5 hours to obtain the hierarchical porous support.

[0053] Weigh out 34.68 g of citric acid, 33.47 g of Zn(NO3)2·6H2O, 3.62 g of Cu(NO3)2·3H2O, 3.26 g of Ce(NO3)3·6H2O, 1.92 g of Mg(NO3)2·6H2O, and 3.25 g of La(NO3)3·6H2O in sequence, and dissolve them in 400 ml of deionized water. Stir until clear to obtain a mixed salt solution.

[0054] Weigh 79.5g of anhydrous sodium carbonate and dissolve it in 500ml of distilled water, stirring until the solution is clear.

[0055] Pour the mixed salt solution into a water bath at 65°C. Add the graded porous carrier precursor to the salt solution and immerse for 2 hours. While stirring continuously, slowly add 1.5 mol / L Na₂CO₃ solution dropwise using a peristaltic pump to co-precipitate until the pH value in the water bath reaches 7.5-8.0, at which point precipitation is complete. Aging is then carried out at 65°C with stirring for 2 hours.

[0056] The aged product was filtered and washed four times with distilled water at 60°C. After washing, it was placed in an oven and dried at 110°C for 12 hours.

[0057] The dried material was placed in a muffle furnace and heated to 450°C at a rate of 3°C / min for 4 hours. After cooling, it was removed.

[0058] Weigh 60g of the above powdered material, add 3.00g of guar gum powder, and slowly add deionized water to mix and knead until a uniform paste with good plasticity is formed. Then, use a twin-screw extruder to extrude the paste through a die with a 3.0 mm orifice to obtain cylindrical strips with a diameter of approximately 3 mm. Dry the obtained strips at 110℃ for 6 hours, and then calcine them in a muffle furnace at a temperature increased to 450℃ at 2℃ / min for 2 hours to obtain desulfurizer B.

[0059] Example 3:

[0060] A method for preparing a high-sulfur-capacity graded porous desulfurizer includes the following steps:

[0061] Take 50g of macroporous alumina microspheres with an average pore size of 50nm, soak them in 500ml of 2wt% nitric acid solution for 2h, wash them with deionized water until the pH of the filtrate is 6-7, and dry them in an oven at 100℃ for 10h to obtain the acid-washed alumina carrier.

[0062] Weigh 56.3 g of Al(NO3)3·9H2O and dissolve it in 300 mL of deionized water. Stir magnetically to form a clear solution. Add dilute ammonia dropwise to adjust the pH to 5.0 to obtain aluminum sol.

[0063] The acid-washed alumina support was added to the alumina sol and transferred to a 500ml hydrothermal reactor. The reaction was carried out at 140℃ for 10h. After cooling and filtration, the mixture was washed three times with deionized water and dried in an oven at 100℃ for 10h to obtain a hierarchical porous support precursor.

[0064] The obtained hierarchical porous support precursor was placed in a muffle furnace and heated to 500℃ at a rate of 1-2℃ / min, and held at that temperature for 3.5 hours to obtain the hierarchical porous support.

[0065] Weigh out 34.68 g of citric acid, 31.24 g of Zn(NO3)2·6H2O, 2.90 g of Cu(NO3)2·3H2O, 5.21 g of Ce(NO3)3·6H2O, 2.69 g of Mg(NO3)2·6H2O, and 4.55 g of La(NO3)3·6H2O, and dissolve them in 400 ml of deionized water. Stir until clear to obtain a mixed salt solution.

[0066] Weigh 79.5g of anhydrous sodium carbonate and dissolve it in 500ml of distilled water, stirring until the solution is clear.

[0067] Pour the mixed salt solution into a water bath at 65°C. Add the graded porous carrier precursor to the salt solution and immerse for 2 hours. While stirring continuously, slowly add 1.5 mol / L Na₂CO₃ solution dropwise using a peristaltic pump to co-precipitate until the pH value in the water bath reaches 7.5-8.0, at which point precipitation is complete. Aging is then carried out at 65°C with stirring for 2 hours.

[0068] The aged product was filtered and washed four times with distilled water at 60°C. After washing, it was placed in an oven and dried at 110°C for 12 hours.

[0069] The dried material is placed in a muffle furnace and heated to 500°C at a rate of 3°C / min for 3 hours, then cooled and removed.

[0070] Weigh 60g of the above powdered material, add 3.00g of guar gum powder, and slowly add deionized water to mix and knead until a uniform paste with good plasticity is formed. Then, use a twin-screw extruder to extrude the paste through a die with a 3.0 mm orifice to obtain cylindrical strips with a diameter of approximately 3 mm. Dry the obtained strips at 110℃ for 6 hours, and then calcine them in a muffle furnace at a temperature increased to 450℃ at 2℃ / min for 2 hours to obtain desulfurizing agent C.

[0071] Comparative Example 1

[0072] A method for preparing a traditional zinc oxide desulfurizing agent includes the following steps:

[0073] Take 50g of macroporous alumina microspheres with an average pore size of 50nm, soak them in 500ml of 2wt% nitric acid solution for 2h, wash them with deionized water until the pH of the filtrate is 6-7, and dry them in an oven at 100℃ for 10h to obtain the acid-washed carrier.

[0074] Weigh out 31.24 g of Zn(NO3)2·6H2O, 2.90 g of Cu(NO3)2·3H2O, 5.21 g of Ce(NO3)3·6H2O, 2.69 g of Mg(NO3)2·6H2O, and 4.55 g of La(NO3)3·6H2O, and dissolve them sequentially in 45 ml of deionized water, stirring until clear. A mixed salt solution is obtained.

[0075] The prepared solution is added dropwise and evenly to the prepared alumina support using a dropper. The support is continuously rolled or stirred during the addition process until no liquid remains.

[0076] The impregnated wet sample was sealed and allowed to age at room temperature for 12 hours. Then it was transferred to a drying oven and dried at 110°C for 12 hours.

[0077] The dried material was placed in a muffle furnace and heated to 450°C at a rate of 3°C / min for 4 hours.

[0078] Weigh 50g of the above powdered material, add 2.50g of guar gum powder, and slowly add deionized water to mix and knead until a uniform paste with good plasticity is formed. Then, use a twin-screw extruder to extrude the paste through a die with a 3.0 mm orifice to obtain cylindrical strips with a diameter of approximately 3 mm. Dry the obtained strips at 110℃ for 6 hours, and then calcine them in a muffle furnace at a temperature increased to 450℃ at 2℃ / min for 2 hours to obtain control sample D.

[0079] Comparative Example 2

[0080] A method for preparing a hierarchical porous desulfurizing agent includes the following steps:

[0081] Weigh 56.3 g of Al(NO3)3·9H2O and dissolve it in 300 mL of deionized water. Stir magnetically to form a clear solution. Add dilute ammonia dropwise to adjust the pH to 5.0 to obtain aluminum sol.

[0082] 50g of macroporous alumina microspheres with an average pore size of 50nm were added to the alumina sol and transferred to a 500ml hydrothermal reactor. The reaction was carried out at 140℃ for 10h. After cooling and filtration, the microspheres were washed three times with deionized water and dried in an oven at 100℃ for 10h to obtain a hierarchical porous carrier precursor.

[0083] The obtained hierarchical porous support precursor was placed in a muffle furnace and heated to 500℃ at a rate of 1-2℃ / min, and held at that temperature for 3.5 hours to obtain the hierarchical porous support.

[0084] Weigh out 34.68 g of citric acid, 31.24 g of Zn(NO3)2·6H2O, 2.90 g of Cu(NO3)2·3H2O, 5.21 g of Ce(NO3)3·6H2O, 2.69 g of Mg(NO3)2·6H2O, and 4.55 g of La(NO3)3·6H2O, and dissolve them sequentially in 400 ml of deionized water, stirring until clear. A mixed salt solution is obtained.

[0085] Weigh 79.5g of anhydrous sodium carbonate and dissolve it in 500ml of distilled water, stirring until the solution is clear.

[0086] Adjust the water bath temperature to 65℃, pour the mixed salt solution into the water bath, and then add the graded porous carrier precursor to the salt solution for 2 hours of soaking. While continuously stirring, slowly add 1.5 mol / L Na₂CO₃ solution dropwise using a peristaltic pump to co-precipitate until the pH value in the water bath reaches 7.5-8.0, at which point precipitation is complete. Aging is then carried out at 65℃ with stirring for 2 hours.

[0087] The aged product was filtered and washed four times with distilled water at 60°C. After washing, it was placed in an oven and dried at 110°C for 12 hours.

[0088] The dried material was placed in a muffle furnace and heated to 450°C at a rate of 3°C / min for 4 hours. After cooling, it was removed.

[0089] Weigh 60g of the above powdered material, add 3.00g of guar gum powder, and slowly add deionized water to mix and knead until a uniform paste with good plasticity is formed. Then, use a twin-screw extruder to extrude the paste through a die with a 3.0 mm orifice to obtain cylindrical strips with a diameter of approximately 3 mm. Dry the obtained strips at 110℃ for 6 hours, and then calcine them in a muffle furnace at a temperature increased to 450℃ at 2℃ / min for 2 hours. This yields control sample E.

[0090] Comparative Example 3

[0091] A method for preparing a hierarchical porous desulfurizing agent includes the following steps:

[0092] Take 50g of macroporous alumina microspheres with an average pore size of 50nm, soak them in 500ml of 2wt% nitric acid solution for 2h, wash them with deionized water until the pH of the filtrate is 6-7, and dry them in an oven at 100℃ for 10h to obtain the acid-washed carrier.

[0093] Weigh 56.3 g of Al(NO3)3·9H2O and dissolve it in 300 mL of deionized water. Stir magnetically to form a clear solution. Add dilute ammonia dropwise to adjust the pH to 5.0 to obtain aluminum sol.

[0094] The acid-washed carrier was added to the aluminum sol and transferred to a 500ml hydrothermal reactor. The reaction was carried out at 140℃ for 10h. After cooling and filtration, the carrier was washed three times with deionized water and dried in an oven at 100℃ for 10h to obtain a hierarchical porous carrier precursor.

[0095] The obtained hierarchical porous support precursor was placed in a muffle furnace and heated to 500℃ at a rate of 1-2℃ / min, and held at that temperature for 3.5 hours to obtain the hierarchical porous support.

[0096] Weigh out 31.24 g of Zn(NO3)2·6H2O, 2.90 g of Cu(NO3)2·3H2O, 5.21 g of Ce(NO3)3·6H2O, 2.69 g of Mg(NO3)2·6H2O, and 4.55 g of La(NO3)3·6H2O, and dissolve them sequentially in 400 ml of deionized water, stirring until clear. A mixed salt solution is obtained.

[0097] Weigh 79.5g of anhydrous sodium carbonate and dissolve it in 500ml of distilled water, stirring until the solution is clear.

[0098] Adjust the water bath temperature to 65℃, pour the mixed salt solution into the water bath, and then add the graded porous carrier precursor to the salt solution for 2 hours of soaking. While continuously stirring, slowly add 1.5 mol / L Na₂CO₃ solution dropwise using a peristaltic pump to co-precipitate until the pH value in the water bath reaches 7.5-8.0, at which point precipitation is complete. Aging is then carried out at 65℃ with stirring for 2 hours.

[0099] The aged product was filtered and washed four times with distilled water at 60°C. After washing, it was placed in an oven and dried at 110°C for 12 hours.

[0100] The dried material was placed in a muffle furnace and heated to 450°C at a rate of 3°C / min for 4 hours. After cooling, it was removed.

[0101] Weigh 60g of the above powdered material, add 3.00g of guar gum powder, and slowly add deionized water to mix and knead until a uniform paste with good plasticity is formed. Then, use a twin-screw extruder to extrude the paste through a die with a 3.0 mm orifice to obtain cylindrical strips with a diameter of approximately 3 mm. Dry the obtained strips at 110℃ for 6 hours, and then calcine them in a muffle furnace at a temperature increased to 450℃ at 2℃ / min for 2 hours. This yields control sample F.

[0102] Desulfurizer evaluation

[0103] This embodiment provides the activity determination of the desulfurizing agent of the present invention, specifically as follows:

[0104] Desulfurizing agent loading: The desulfurizing agents prepared in each of Examples 1-3 and Comparative Examples 1-3 are crushed into 0.85-1.18mm particles, and 2ml is weighed and loaded into a Φ11*1.5mm stainless steel reaction tube.

[0105] Raw material gas composition and sulfur capacity determination: The raw material composition (v / v%) is shown in Table 1.

[0106]

[0107] The test conditions are shown in Table 2:

[0108]

[0109] The results of specific surface area measurement and desulfurization performance test are shown in Table 3:

[0110]

[0111] The test results show that the desulfurizers (A, B, C) prepared using the method of this invention have significantly higher specific surface areas than the comparative desulfurizers (D, E, F), and their sulfur penetration capacity is increased by more than 60%. This fully demonstrates that the high specific surface area of ​​this invention originates from a complete hierarchical porous structure, and its high sulfur capacity originates from the synergistic effect of high specific surface area and highly dispersed active components. It also proves that the three-step process of acid washing, hydrothermal mesoporous construction, and complexation co-precipitation is indispensable.

[0112] In summary, this invention successfully provides a method for preparing a desulfurizing agent with high sulfur capacity, high activity, and easy promotion, which has good prospects for industrial application.

[0113] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

[0114] This background section is provided to generally present the context of the invention. The work of the currently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither expressly nor impliedly acknowledged as prior art to the invention.

Claims

1. A method for preparing a high-sulfur-capacity, graded porous desulfurizing agent, characterized in that, This desulfurizing agent uses zinc oxide as the active component. It is produced by in-situ hydrothermal modification of macroporous alumina to establish a nanostructure on its surface, forming a hierarchical porous carrier with both a macroporous framework and a mesoporous shell. The desulfurizing agent is then obtained through precipitation. The specific steps include: (1) Carrier pretreatment: The macroporous alumina microspheres were soaked in dilute nitric acid solution, then washed until neutral, and then dried to obtain the acid-washed alumina carrier; (2) Preparation and adjustment of aluminum sol: Dissolve aluminum nitrate nonahydrate in deionized water, stir to form a clear solution, and then adjust the pH value of the solution with alkaline solution to obtain aluminum sol; (3) In-situ hydrothermal growth: The alumina support obtained by acid washing in step (1) is mixed with the aluminum sol obtained in step (2), and then placed together in a hydrothermal reactor for hydrothermal reaction. After the reaction is completed, the product is cooled, washed and dried to obtain a graded porous support precursor. (4) The graded porous carrier precursor obtained in step (3) is placed in a muffle furnace for calcination to obtain a graded porous carrier. (5) Preparation of mixed salt-complexing agent solution: Dissolve citric acid and nitrates of zinc, copper, cerium, magnesium and lanthanum in deionized water to form a mixed salt solution; (6) Impregnation and coprecipitation: The graded porous carrier obtained in step (4) is impregnated in the mixed salt solution obtained in step (5), and then sodium carbonate precipitant solution is added dropwise to the system. During this process, the system is stirred continuously and a coprecipitation reaction is carried out, followed by aging. (7) Post-processing: The product aged in step (6) is washed, dried and calcined; (8) Molding: Add binder and water to the material after roasting in step (7) and extrude it into strips, then dry and roast it to obtain the finished desulfurizer.

2. The preparation method according to claim 1, characterized in that: In step (2), the alkaline solution used is ammonia water, urea solution or sodium hydroxide solution; the pH value of the solution is adjusted to 4-7.

3. The preparation method according to claim 1, characterized in that: In step (3), the temperature of the hydrothermal reaction is 120-180℃ and the reaction time is 8-12 hours.

4. The preparation method according to claim 1, characterized in that, The roasting procedure in step (4) is as follows: the temperature is increased to 500-600℃ at a rate of 1-2℃ / min and kept constant for 3-5 hours.

5. The preparation method according to claim 1, characterized in that, In step (5), the ratio of the amount of citric acid added to the total amount of metal elements is 1.0-1.5:1, based on the total molar amount of metal elements; the molar percentage of each metal element in the mixed salt solution is: Zn 60-80%, Cu 5-15%, Ce 5-10%, Mg 2-8%, La 2-8%.

6. The preparation method according to claim 1, characterized in that, In step (6), the temperature of the co-precipitation reaction is 60-70℃, and the pH value is controlled at 7.0-9.5; the aging time is 0.2-3 hours.

7. The preparation method according to claim 1, characterized in that, The roasting procedure in step (7) is as follows: the temperature is increased to 400-500℃ at a rate of 2-5℃ / min and kept constant for 2-5 hours.

8. The preparation method according to claim 1, characterized in that, The binder mentioned in step (8) is guar gum powder, and the ratio of its addition amount to the mass of the material after roasting in step (7) is 0.05-0.1:1; the roasting procedure is to heat to 450℃ at a rate of 2℃ / min and roast for 2 hours.

9. A high-sulfur-capacity, graded porous desulfurizer prepared by the method according to any one of claims 1 to 8.

10. The application of the high sulfur capacity graded porous structure desulfurizer according to claim 9 in the removal of hydrogen sulfide from natural gas, syngas, biogas or refinery gas.

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