Copper-based adsorbent based on Lewis acid regulation as well as preparation method and application of copper-based adsorbent

Abstract

The invention relates to a copper-based adsorbent based on Lewis acid regulation, which is prepared by the following steps: adding aluminum isopropoxide into an ethanol solution containing P123 and concentrated nitric acid to form a dispersion solution, evaporating and drying, and carrying out heat treatment at 550-750 DEG C to obtain an alumina carrier rich in Lewis acid sites; and dropwise adding a mixed metal salt aqueous solution of copper and zinc and a sodium carbonate aqueous solution into the water suspension of the alumina carrier for deposition and precipitation reaction to obtain an adsorbent precursor, and roasting to obtain the adsorbent. Through the interaction of the copper active component in the adsorbent and the Lewis acid site on the alumina carrier, the adsorption and activation of the adsorbent on thiophene are enhanced, and the more efficient ultra-deep removal effect of thiophene in coke oven gas is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of coke oven gas purification, and relates to a desulfurization adsorbent for coke oven gas, in particular to an adsorbent for ultra-deep removal of sulfur-containing compound thiophene in coke oven gas. Background Art

[0002] Coke oven gas is a high-quality raw material gas resource, which is used for the synthesis of various raw materials, realizing the effective utilization of coke oven gas. Among them, synthesizing natural gas through methanation reaction is one of its important utilization ways.

[0003] Coke oven gas not only contains components such as H2, CH4, CO, and CO2, but also contains complex sulfur components, including inorganic sulfur (H2S) and various complex organic sulfurs (CS2, COS, RSH, C4H4S, etc.). Among them, inorganic sulfur and most organic sulfurs are relatively easy to remove, while thiophene is the most difficult to remove.

[0004] However, ppmv-level thiophene sulfide in coke oven gas will cause the poisoning and inactivation of the methanation reaction catalyst, shortening its service life, and severely restricting its subsequent utilization. Therefore, it is of great significance to develop an excellent thiophene desulfurization adsorbent before the methanation reaction.

[0005] CN 112138625A discloses an adsorption desulfurization agent for ultra-deep removal of thiophene in coke oven gas and its preparation method, which introduces Al2O3, NiO, and ZrO2 into the copper-zinc binary system. Through the synergistic effect of metal promoters on the copper-zinc binary system, the surface area of the adsorbent is increased, thereby improving its desulfurization activity, and the breakthrough sulfur capacity reaches 24.4 mg / g. However, on the one hand, the raw materials nickel nitrate and zirconium nitrate required by this method are relatively high in cost, 30,000 yuan / ton and 35,000 yuan / ton respectively; on the other hand, they belong to dangerous chemicals, with relatively high transportation and storage risks; the preparation cost of the adsorbent is relatively high, and it is difficult to meet the requirements of large-scale industrial applications.

[0006] Furthermore, CN 115254006A discloses a desulfurization adsorbent for ultra-deep removal of thiophene in coke oven gas and its preparation method, which further introduces pseudo-boehmite, NiO, and ZrO2 into the copper-zinc binary system. Using pseudo-boehmite as the raw material for the alumina carrier, by increasing the content of pseudo-boehmite and reducing the content of zirconia, the desulfurization performance of the adsorbent is greatly improved and the cost is reduced. However, this adsorbent still has the problem of low sulfur capacity (the breakthrough sulfur capacity is 37.91 mg / g), and at the same time, the raw materials nickel nitrate and zirconium nitrate used in the preparation process of the adsorbent still do not fall out of the category of dangerous chemicals, and the cost is still relatively high. Summary of the Invention

[0007] The object of the present invention is to provide a Lewis acid-regulated copper-based adsorbent and a preparation method thereof. By selecting a suitable heat treatment temperature to regulate the Lewis acid sites of the alumina support, and then loading the metal active components, precise regulation of the content and distribution of the Lewis acid sites is achieved, effectively improving the desulfurization performance of the regulated copper-based adsorbent.

[0008] To achieve the above object, the present invention provides a Lewis acid-regulated copper-based adsorbent, which first prepares an alumina support rich in Lewis acid sites by an evaporation-induced self-assembly method, and then drops an aqueous solution of a mixed metal salt of copper and zinc and an aqueous solution of sodium carbonate into the aqueous suspension of the above alumina support to carry out a deposition precipitation reaction to obtain an adsorbent precursor, and the adsorbent obtained after calcination.

[0009] Among them, the alumina support rich in Lewis acid sites is an alumina support obtained by adding aluminum isopropoxide to an ethanol solution containing P123 and concentrated nitric acid to form a dispersion solution, evaporating and drying, and then heat treating at 550-750 °C.

[0010] For the Lewis acid-regulated copper-based adsorbent provided by the present invention, through the interaction between the copper active component in the adsorbent and the Lewis acid sites on the alumina support, the adsorption and activation of thiophene by the adsorbent are enhanced, and a more efficient ultra-depth removal effect of thiophene in coke oven gas is achieved.

[0011] Furthermore, the present invention also provides a preparation method of the Lewis acid-regulated copper-based adsorbent, which specifically includes: S1. Add P123 and concentrated nitric acid to ethanol to form a uniform dispersion solution, and then add aluminum isopropoxide and stir evenly to obtain a mixed solution; S2. After evaporating and drying the mixed solution, heat it to 550-750 °C for heat treatment, and obtain an alumina support through evaporation-induced self-assembly; S3. Prepare an aqueous solution of a mixed metal salt with a copper salt and a zinc salt, and prepare an aqueous solution of a carbonate with a precipitating agent carbonate; S4. Prepare an aqueous suspension of the alumina support, and drop the aqueous solution of the mixed metal salt and the aqueous solution of sodium carbonate into it in a synchronous manner to carry out a deposition precipitation reaction; S5. Dry the reaction product to obtain an adsorbent precursor, and obtain a copper-based adsorbent after calcination in an air atmosphere.

[0012] Among them, specifically, the time for heat treatment to prepare the alumina support is preferably 3-9 h.

[0013] The present invention first prepares a light yellow alumina support by an evaporation-induced self-assembly method, which is amorphous or γ-alumina, with a pore diameter of 2-10 nm and a specific surface area of 70-85 m 2 / g, with strong Lewis acid characteristics.

[0014] Furthermore, the dosage of the alumina support for the deposition precipitation reaction in the present invention is 1-3% of the mass of the metal salt.

[0015] Specifically, in the present invention, the mixed metal salt aqueous solution and the sodium carbonate aqueous solution are synchronously dropped into the aqueous suspension of the alumina support at a dropping rate of 2-5 mL / min to promote the uniform progress of the deposition precipitation reaction.

[0016] More specifically, the present invention preferably controls the dropping rate of the sodium carbonate aqueous solution to be 1.2-1.5 times that of the mixed metal salt aqueous solution, and at the same time controls the pH value of the reaction system to be maintained at 7.4-7.6 during the deposition precipitation reaction.

[0017] More specifically, the deposition precipitation reaction in the present invention is preferably carried out at a reaction temperature of 75-80 °C.

[0018] In the preparation method of the copper-based adsorbent of the present invention, an aging treatment process of the deposition precipitation reaction product may also be included. Specifically, the reaction product is further heated to 80-90 °C for aging treatment for 2-4 h.

[0019] Specifically, it is preferably to dry the deposition precipitation reaction product at 60-120 °C for 10-48 h to prepare an adsorbent precursor.

[0020] More specifically, the present invention preferably calcines the adsorbent precursor in an air atmosphere at 350-400 °C for 3-6 h to prepare the copper-based adsorbent.

[0021] The copper-based adsorbent prepared by the present invention can be used as a desulfurization adsorbent for ultra-deep removal of thiophene in coke oven gas.

[0022] After the copper-based adsorbent prepared by the present invention is reduced in a hydrogen atmosphere in a fixed-bed device, a simulated coke oven gas containing a certain concentration of thiophene is introduced for desulfurization treatment. It is detected that the breakthrough time of the prepared copper-based adsorbent is greater than 300 min, and the breakthrough sulfur capacity is not less than 40 mg / g.

[0023] The present invention effectively improves the adsorption performance of the prepared copper-based adsorbent by simply regulating the Lewis acid sites of the alumina support during the preparation process. The prepared adsorbent not only has high adsorption selectivity and adsorption capacity for sulfides, but also has a relatively simple preparation process and low production cost. Description of the Drawings

[0024] Figure 1 is the nitrogen adsorption and desorption curve of the alumina support prepared in each example and comparative example of the present invention.

[0025] Figure 2 It is the pore size distribution diagram of the alumina carriers prepared in each embodiment and comparative example of the present invention.

[0026] Figure 3 It is the nitrogen adsorption - desorption curve of the copper - based adsorbents prepared in each embodiment and comparative example of the present invention.

[0027] Figure 4 It is the pore size distribution diagram of the copper - based adsorbents prepared in each embodiment and comparative example of the present invention.

[0028] Figure 5 It is the XRD spectrum of the alumina carriers prepared in each embodiment and comparative example of the present invention.

[0029] Figure 6 It is the in - situ diffuse reflectance infrared spectrum of NH3 of the alumina carriers prepared in each embodiment and comparative example of the present invention.

[0030] Figure 7 It is the in - situ diffuse reflectance infrared spectrum of NH3 and the corresponding intensity diagram of the copper - based adsorbents prepared in each embodiment and comparative example of the present invention.

[0031] Figure 8 It is the breakthrough time curve of thiophene by the copper - based adsorbents prepared in each embodiment and comparative example of the present invention.

[0032] Figure 9 It is the breakthrough adsorption amount of thiophene by the copper - based adsorbents prepared in each embodiment and comparative example of the present invention. Embodiment

[0033] The following further describes in detail the specific embodiments of the present invention in conjunction with the drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, so that those skilled in the art can fully understand and utilize the present invention well.

[0034] However, the present invention can be implemented in many other ways different from those described in the following examples, and those skilled in the art can also make similar improvements without departing from the connotation of the present invention. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0035] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art. The terms used in the specification of the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0036] The term "and / or" used in the present invention includes any and all combinations of one or more of the related listed items.

[0037] The terms "multiple", "diverse", "multiple times", "multiple groups", etc. used in the present invention, unless otherwise specified, refer to a quantity greater than or equal to 2; "above" includes the number itself, for example, "two or more" includes two, three or more.

[0038] The term "preferred" used in the present invention is only for describing embodiments or examples with better effects and does not constitute a limitation on the protection scope of the present invention.

[0039] For the production processes, experimental methods or detection methods involved in the embodiments of the present invention, unless otherwise specified, they are all conventional methods in the prior art, and their names and / or abbreviations are all conventional names in the art and are very clear and definite in the relevant application fields. Those skilled in the art can understand the conventional process steps according to the names and apply the corresponding equipment, in accordance with the conventional conditions or the conditions recommended by the manufacturer, or refer to the experimental methods known in the art for implementation.

[0040] For the various instruments, equipment, raw materials or reagents used in the embodiments of the present invention, there are no special restrictions on the sources. They are all conventional products that can be obtained through regular commercial channels, and can also be prepared according to the conventional methods well-known to those skilled in the art.

[0041] In the following embodiments of the present invention, through the following specific methods, first, an alumina support is prepared by an evaporation-induced self-assembly method, and then the Lewis acid-regulated copper-based adsorbent is prepared by a deposition-precipitation method.

[0042] First, an alumina support is prepared by an evaporation-induced self-assembly method:

[0043] P123 and concentrated nitric acid are added to a certain amount of ethanol and stirred to form a uniformly dispersed solution, then aluminum isopropoxide is added and stirred continuously. Then the mixed solution is dried to obtain a pale yellow product. Finally, the obtained product is heated to 550-750 °C for heat treatment, and an alumina support rich in Lewis acid sites can be prepared.

[0044] In the following specific embodiments, preferably, the obtained product is heat-treated for 3-9 h.

[0045] In the following specific embodiments, preferably, the prepared alumina support is dispersed in water with a volume 150-200 times that of the alumina support to form a water suspension for preparing the adsorbent.

[0046] Secondly, a copper-based adsorbent is prepared by a deposition-precipitation method:

[0047] Prepare an aqueous solution of mixed metal salts with copper salts and zinc salts, and an aqueous solution of carbonate as the precipitant. According to the mass ratio of alumina support to metal salts being 1 - 3%, simultaneously drip the aqueous solution of mixed metal salts and the aqueous solution of sodium carbonate into the aqueous suspension of alumina support for deposition precipitation reaction. After the reaction product is aged, it is dried to obtain the adsorbent precursor, and then calcined to obtain the adsorbent for ultra-deep removal of thiophene in coke oven gas.

[0048] In the following specific examples, it is preferred to dissolve copper salts and zinc salts in water to prepare an aqueous solution of mixed metal salts with a total concentration of copper and zinc ions of 0.3 mol / L.

[0049] In the following specific examples, it is preferred to dissolve the precipitant carbonate in water to prepare an aqueous solution of sodium carbonate with a concentration of 0.3 mol / L.

[0050] In the following specific examples, it is preferred to control the dropping rate of the solution at 2 - 5 mL / min. More preferably, control the dropping rate so that the dropping rate of the aqueous solution of sodium carbonate is 1.2 - 1.5 times that of the aqueous solution of mixed metal salts, and control the pH value of the reaction system at 7.4 - 7.6.

[0051] In the following specific examples, the reaction temperature of the deposition precipitation reaction is preferably 75 - 80 °C, and the stirring speed is controlled at 1000 - 1300 revolutions per minute during the reaction process.

[0052] In the following specific examples, the reaction product is further heated to 80 - 90 °C and aged for 2 - 4 h.

[0053] In the following specific examples, the reaction product is dried at 60 - 120 °C for 10 - 48 h to prepare the adsorbent precursor.

[0054] In the following specific examples, the adsorbent precursor is calcined in an air atmosphere at a heating rate of 5 - 8 °C / min to 350 - 400 °C for 3 - 6 h to obtain the copper-based adsorbent for removing thiophene.

[0055] Unless otherwise specified, for the dosage of raw material components, temperature, time and other measurement parameters involved in the embodiments of the present invention, there may be slight deviations within the weighing or measurement accuracy range, and acceptable deviations caused by instrument test accuracy or operation accuracy are allowed. Example

[0056] Example 1

[0057] Prepare the alumina support by the evaporation-induced self-assembly method:

[0058] Add 10 g of P123 and 15 mL of concentrated nitric acid to 200 mL of ethanol, stir to form a uniformly dispersed solution, then add 20.4 g of aluminum isopropoxide, and continue stirring to obtain a mixed solution.

[0059] Dry the mixed solution to obtain a pale yellow sample, heat it to 550 °C and perform heat treatment for 6 h to prepare an alumina support, denoted as A-1.

[0060] Prepare a copper-based adsorbent by the coprecipitation method:

[0061] Weigh 7.248 g of copper nitrate trihydrate and 8.925 g of zinc nitrate hexahydrate, dissolve them in 200 mL of deionized water to prepare a mixed metal salt solution.

[0062] Weigh 9.533 g of anhydrous sodium carbonate, dissolve it in 300 mL of deionized water to prepare a sodium carbonate solution.

[0063] Add 0.306 g of the alumina support A-1 to a reaction vessel containing 50 mL of deionized water, and stir for 15 min to form an alumina suspension.

[0064] Heat the alumina suspension to 75 °C, and while maintaining a stirring speed of 1000 rpm, add the above-mentioned mixed metal salt solution and sodium carbonate solution dropwise to the suspension for reaction. During the dropping process, control the dropping rate of the sodium carbonate solution to be 1.2 times that of the mixed metal salt solution, and keep the pH value of the reaction solution at 7.4.

[0065] After the dropping is completed, raise the temperature of the reaction product to 80 °C and age for 2 h, cool to room temperature, filter by suction, wash the filter cake with deionized water 3 - 6 times, and dry at 110 °C for 12 h to obtain an adsorbent precursor.

[0066] Place the dried adsorbent precursor in a tube furnace, heat it to 350 °C at a rate of 3 °C / min, and calcine it in an air atmosphere for 4 h to prepare a copper-based adsorbent, denoted as CZA-1.

[0067] Example 2

[0068] Prepare an alumina support by the evaporation-induced self-assembly method:

[0069] Add 10 g of P123 and 15 mL of concentrated nitric acid to 200 mL of ethanol, stir to form a uniformly dispersed solution, then add 20.4 g of aluminum isopropoxide, and continue stirring to obtain a mixed solution.

[0070] Dry the mixed solution to obtain a pale yellow sample, heat it to 650 °C and perform heat treatment for 6 h to prepare an alumina support, denoted as A-2.

[0071] Prepare a copper-based adsorbent by the coprecipitation method:

[0072] Weigh 7.248 g of copper nitrate trihydrate and 8.925 g of zinc nitrate hexahydrate, dissolve them in 200 mL of deionized water, and prepare a mixed metal salt solution.

[0073] Weigh 9.533 g of anhydrous sodium carbonate, dissolve it in 300 mL of deionized water, and prepare a sodium carbonate solution.

[0074] Add 0.306 g of alumina support A-2 to a reaction vessel containing 50 mL of deionized water, and stir for 15 min to form an alumina suspension.

[0075] Heat the alumina suspension to 75 °C, and while maintaining a stirring speed of 1000 rpm, add the above-mentioned mixed metal salt solution and sodium carbonate solution dropwise to the suspension for reaction. During the dropping process, control the dropping rate of the sodium carbonate solution to be 1.2 times that of the mixed metal salt solution, and keep the pH value of the reaction solution at 7.4.

[0076] After the dropping is completed, raise the temperature of the reaction product to 80 °C and age for 2 h, cool to room temperature, perform suction filtration, wash the filter cake with deionized water 3 - 6 times, and dry at 110 °C for 12 h to obtain the adsorbent precursor.

[0077] Place the dried adsorbent precursor in a tubular furnace, heat it to 350 °C at a rate of 3 °C / min, and calcine it in an air atmosphere for 4 h to prepare a copper-based adsorbent, denoted as CZA-2.

[0078] Example 3

[0079] Prepare an alumina support by the evaporation-induced self-assembly method:

[0080] Add 10 g of P123 and 15 mL of concentrated nitric acid to 200 mL of ethanol, stir to form a uniformly dispersed solution, and then add 20.4 g of aluminum isopropoxide and continue stirring to obtain a mixed solution.

[0081] Dry the mixed solution to obtain a pale yellow sample, heat it to 750 °C and perform heat treatment for 6 h to prepare an alumina support, denoted as A-3.

[0082] Prepare a copper-based adsorbent by the co-precipitation method:

[0083] Weigh 7.248 g of copper nitrate trihydrate and 8.925 g of zinc nitrate hexahydrate, dissolve them in 200 mL of deionized water, and prepare a mixed metal salt solution.

[0084] Weigh 9.533 g of anhydrous sodium carbonate, dissolve it in 300 mL of deionized water, and prepare a sodium carbonate solution.

[0085] Add 0.306 g of alumina support A-3 to a reaction vessel containing 50 mL of deionized water, and stir for 15 min to form an alumina suspension.

[0086] Heat the alumina suspension to 75 °C, and while maintaining a stirring speed of 1000 rpm, add the above mixed metal salt solution and sodium carbonate solution dropwise to the suspension for reaction. During the dropping process, control the dropping rate of the sodium carbonate solution to be 1.2 times that of the mixed metal salt solution, and maintain the pH value of the reaction solution at 7.4.

[0087] After the dropping is complete, raise the temperature of the reaction product to 80 °C and age for 2 h, cool to room temperature, filter by suction, wash the filter cake with deionized water 3 - 6 times, and dry at 110 °C for 12 h to obtain the adsorbent precursor.

[0088] Place the dried adsorbent precursor in a tubular furnace, heat it to 350 °C at a rate of 3 °C / min, and calcine in an air atmosphere for 4 h to prepare a copper-based adsorbent, denoted as CZA-3.

[0089] Comparative Example 1

[0090] Prepare an alumina support by the evaporation-induced self-assembly method:

[0091] Add 10 g of P123 and 15 mL of concentrated nitric acid to 200 mL of ethanol, stir to form a uniformly dispersed solution, and then add 20.4 g of aluminum isopropoxide and continue stirring to obtain a mixed solution.

[0092] Dry the mixed solution to obtain a pale yellow sample, heat it to 450 °C and perform heat treatment for 6 h to prepare an alumina support, denoted as A-4.

[0093] Prepare a copper-based adsorbent by the coprecipitation method:

[0094] Weigh 7.248 g of copper nitrate trihydrate and 8.925 g of zinc nitrate hexahydrate, dissolve them in 200 mL of deionized water to prepare a mixed metal salt solution.

[0095] Weigh 9.533 g of anhydrous sodium carbonate, dissolve it in 300 mL of deionized water to prepare a sodium carbonate solution.

[0096] Add 0.306 g of alumina support A-4 to a reaction vessel containing 50 mL of deionized water, and stir for 15 min to form an alumina suspension.

[0097] Heat the alumina suspension to 75 °C, and while maintaining a stirring speed of 1000 rpm, add the above mixed metal salt solution and sodium carbonate solution dropwise to the suspension for reaction. During the dropping process, control the dropping rate of the sodium carbonate solution to be 1.2 times that of the mixed metal salt solution, and maintain the pH value of the reaction solution at 7.4.

[0098] After the dropping was completed, the reaction product was heated to 80 °C for aging for 2 h, cooled to room temperature, filtered by suction, and the filter cake was washed with deionized water for 3 to 6 times and dried at 110 °C for 12 h to obtain the adsorbent precursor.

[0099] The dried adsorbent precursor was placed in a tube furnace and heated to 350 °C at a rate of 3 °C / min and calcined in an air atmosphere for 4 h to prepare a copper-based adsorbent, denoted as CZA-4.

[0100] Figure 1 and Figure 2 The nitrogen adsorption-desorption curves and pore size distribution diagrams of the alumina supports prepared in Examples 1 to 3 and Comparative Example 1 at different heat treatment temperatures were respectively given. Figure 3 and Figure 4 were respectively the nitrogen adsorption-desorption curves and pore size distribution diagrams of the copper-based adsorbents prepared in Examples 1 to 3 and Comparative Example 1.

[0101] The test results show that whether it is the alumina support material or the copper-based adsorbent itself, the pore size distribution and specific surface area between each example and the comparative example change little within the experimental range, thus proving that the contribution of the pore structure to the desulfurization performance of the adsorbent can be ignored.

[0102] Figure 5 The XRD patterns of the alumina supports prepared in Examples 1 to 3 and Comparative Example 1 at different heat treatment temperatures were provided. It can be seen that with the increase of the heat treatment temperature, the crystal structure of alumina gradually changes.

[0103] Among them, alumina heat-treated under low-temperature conditions below 650 °C usually exhibits amorphous or low-crystallinity characteristics, and its XRD pattern shows broad and indistinct diffraction peaks, reflecting the disorder of the crystal structure. Due to the lack of long-range ordered arrangement in this structure, there are a large number of unsaturated coordinated aluminum ions (Al 3+ ), and lattice defects on the surface, thus endowing it with high surface activity. Unsaturated Al 3+ ions can serve as typical Lewis acid centers and coordinate with molecules by accepting electron pairs.

[0104] In addition, low-temperature heat treatment helps to retain more surface hydroxyl groups (-OH), and more active Al 3+ sites can also be exposed during their removal process.

[0105] Therefore, the amorphous or low-crystallinity alumina surface can provide abundant Lewis acid sites, which will significantly enhance its adsorption and desulfurization performance.

[0106] As the heat treatment temperature rises to 750°C, the alumina crystal structure gradually transforms into the more thermodynamically stable γ-Al2O3 phase, and the XRD spectrum shows obvious characteristic diffraction peaks at 2θ=19.4°, 31.9°, 37.6°, 39.5°, 45.8°, 60.9° and 67.0°, and the peak shape tends to be sharp and the intensity is significantly enhanced. This phenomenon indicates that the degree of crystallization of the material is significantly improved, the grain size is increased, and the surface disordered structure and defect sites are greatly reduced.

[0107] The Lewis acid sites of alumina mainly come from the unsaturated coordinated Al 3+ ions and other surface defects, and the formation of high crystallinity makes these highly active surface sites tend to be saturated, or buried inside the crystal and not easily exposed, resulting in a significant reduction in the number of surface active sites; in addition, high-temperature heat treatment also promotes the removal of surface hydroxyl groups, further weakening the Lewis acid properties of alumina, thereby reducing its adsorption and desulfurization activity.

[0108] Although the aluminum oxide has not yet been transformed into a high-crystallinity γ-Al2O3 phase at 650℃, and is still in an amorphous or low-crystallization state, the number of Lewis acid sites has increased significantly compared to the sample heat-treated at 450℃. This phenomenon is mainly attributed to the more thorough dehydration and dehydroxylation process on the aluminum oxide surface at higher heat treatment temperatures, which makes some of the Al2O3 coordinated by hydroxyl or water molecules 3+ ions are exposed to form unsaturated coordinated Al 3+ , thus effectively generating Lewis acid sites. However, the aluminum oxide heat-treated at 450℃ still retains a large number of hydrated hydroxyl structures, and the surface Al 3+ It mostly exists in saturated coordination and is difficult to provide empty orbitals to accept electron pairs, so its Lewis acidity is weak.

[0109] Figure 6 Further, the NH3 in-situ infrared spectra of the alumina carriers prepared at different heat treatment temperatures in Examples 1 to 3 and Comparative Example 1 respectively indicate the differences in Lewis acid sites in the carriers. -1 The adsorption peak at is usually related to the adsorption of ammonia molecules on Lewis acid sites, and is a typical characteristic peak for characterizing Lewis acid sites. Among them, when the alumina carrier A-2 of Example 2 was at 200°C, the number of Lewis acid sites increased significantly, indicating that relatively abundant Lewis acid sites were formed on the carrier surface at this temperature. In contrast, the number of Lewis acid sites of the alumina carrier A-4 of Comparative Example 1 was the lowest.

[0110] and then, Figure 7 The Lewis acid site content of the copper-based adsorbent loaded with copper and zinc was also determined.-1 The adsorption peak corresponds to the asymmetric bending vibration of NH3 molecules, while the adsorption peak at 1200 - 1300 cm -1 is related to the symmetric bending vibration of NH3 molecules, and both are typical characteristic peaks for characterizing Lewis acid sites. It can be clearly seen from the intensity map that the copper-based adsorbent CZA-2 has abundant Lewis acid sites, while the number of Lewis acid sites of the copper-based adsorbent CZA-4 in Comparative Example 1 is the least.

[0111] Application Example 1

[0112] The copper-based adsorbents CZA-1 - CZA-4 prepared in Examples 1 - 3 and Comparative Example 1 were respectively taken and placed in the middle of a fixed-bed reaction device. After being reduced in a hydrogen atmosphere at 200 °C for 3 h, while maintaining the reaction temperature at 200 °C, a simulated coke oven gas containing 300 ppmv thiophene (58% H2, 26% CH4, 8% CO, 3% CO2, 4% N2, 1% O2) was introduced into the fixed-bed reactor for desulfurization reaction.

[0113] The change in the thiophene content at the outlet of the fixed-bed reaction device was monitored online, and the breakthrough time and breakthrough sulfur capacity of each copper-based adsorbent for thiophene were calculated. The results are as Figure 8 and Figure 9 shown.

[0114] Among them, the breakthrough times of CZA-1 - CZA-3 for thiophene are 290 min, 325 min, and 310 min respectively, and the breakthrough sulfur capacities are 41.2 mg / g, 43.3 mg / g, and 40.0 mg / g respectively; however, the breakthrough time and breakthrough sulfur capacity of CZA-4 for thiophene are only 244 min and 38.1 mg / g respectively.

[0115] Figure 8 and Figure 9 show that after treating the alumina support at different heat treatment temperatures and then loading the active components to obtain copper-based adsorbents, their desulfurization activities are different.

[0116] Therefore, by regulating the content of Lewis acid sites in the copper-based adsorbent, it has a significant impact on its activity for removing thiophene, and this phenomenon can be attributed to the key role played by Lewis acid sites in the desulfurization reaction.

[0117] Due to the strong polarity of the sulfur atom in the thiophene molecule, it is easily affected when interacting with the adsorbent. During the adsorption process, the Lewis acid sites can form a coordination interaction with the sulfur atom in the thiophene molecule, thereby enhancing its adsorption ability. This interaction not only improves the adsorption efficiency of thiophene, but also promotes the electron transfer between the thiophene molecule and the surface of the adsorbent, thus providing the necessary electron support for the desulfurization reaction. Especially during the desulfurization process, the Lewis acid sites can effectively promote the cleavage reaction of the C-S bond in the thiophene molecule, and this reaction is the key step for thiophene removal.

[0118] In summary, by regulating the quantity and distribution of the Lewis acid sites, the desulfurization activity of the adsorbent can be effectively optimized, thereby significantly improving its performance in the desulfurization of coke oven gas.

[0119] Further research shows that the density and strength of the Lewis acid sites on the surface of the adsorbent directly determine the desulfurization efficiency of the adsorbent in practical applications. Therefore, precisely regulating these sites can not only improve the desulfurization performance, but also expand the application range of the adsorbent, providing a theoretical basis for the optimization of industrial desulfurization technologies.

[0120] In the present invention, by regulating the surface acidic environment through the heat treatment conditions of the alumina support, the quantity and strength of the L acid sites can be effectively adjusted, thereby optimizing the coordination environment of the copper species, improving the dispersion and stability of the active metal, and overall enhancing the desulfurization efficiency of the adsorbent.

[0121] The technical features of the above embodiments of the present invention can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as falling within the scope described in the specification of the present invention.

[0122] The above embodiments represent several relatively specific and detailed implementation manners of the present invention, but should not be construed as limiting the protection scope of the present invention. It should be noted that those of ordinary skill in the art can also make several substitutions, deformations or improvements without departing from the principle and purpose of the present invention, and all should be included in the protection scope of the present invention.

Claims

1. A copper-based adsorbent based on Lewis acid regulation, which is to first prepare an alumina carrier rich in Lewis acid sites by evaporation-induced self-assembly method, then drop a mixed metal salt aqueous solution of copper and zinc and a sodium carbonate aqueous solution into a water suspension of the alumina carrier to perform a deposition precipitation reaction to obtain an adsorbent precursor, and then calcine to obtain an adsorbent, wherein: The alumina carrier rich in Lewis acid sites is prepared by adding aluminum isopropoxide to an ethanol solution containing P123 and concentrated nitric acid to form a dispersed solution, evaporating and drying the solution, and then heat-treating the solution at 550-750°C to obtain the alumina carrier.

2. The method for preparing the copper-based adsorbent based on Lewis acid regulation according to claim 1, comprising: S1, adding P123 and concentrated nitric acid into ethanol to form a uniformly dispersed solution, and then adding aluminum isopropoxide and stirring to obtain a mixed solution; S2, evaporating and drying the mixed solution, heating it to 550-750° C. for heat treatment, and obtaining an alumina carrier by evaporation-induced self-assembly; S3, preparing a mixed metal salt aqueous solution with copper salt and zinc salt, and preparing a carbonate aqueous solution with a precipitant carbonate; S4, preparing an aqueous suspension of an alumina carrier, and simultaneously adding dropwise a mixed metal salt aqueous solution and a sodium carbonate aqueous solution to perform a deposition and precipitation reaction; S5. The reaction product is dried to obtain an adsorbent precursor, and then calcined in an air atmosphere to obtain a copper-based adsorbent.

3. The preparation method according to claim 2, characterized in that Heat treatment time is 3 to 9 hours.

4. The preparation method according to claim 2, characterized in that The amount of alumina carrier is 1 to 3% of the mass of the metal salt.

5. The preparation method according to claim 2, characterized in that Control the dropping speed to 2-5 mL / min.

6. The preparation method according to claim 5, characterized in that The dropping rate of the sodium carbonate aqueous solution is controlled to be 1.2 to 1.5 times of the dropping rate of the mixed metal salt aqueous solution, and the pH value of the system is maintained at 7.4 to 7.

6.

7. The preparation method according to claim 2, characterized in that The deposition precipitation reaction is carried out at 75-80°C.

8. The preparation method according to claim 2, characterized in that The method also includes heating the deposition precipitation reaction product to 80-90° C. and subjecting the product to aging treatment for 2-4 hours.

9. The preparation method according to claim 2, characterized in that The adsorbent precursor is calcined at 350-400° C. in an air atmosphere for 3-6 hours.

10. Use of the copper-based adsorbent regulated by Lewis acid according to claim 1 as a desulfurization adsorbent in the deep removal of thiophene in coke oven gas.

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