An energy-saving composite desulfurizing agent and its production process

Abstract

This invention provides an energy-saving composite desulfurizing agent and its production process, belonging to the field of gas purification technology. The process includes the following steps: Step S1, preparing a spray-drying slurry using deionized water, CTAB, PMMA nanosphere emulsion, tannic acid, ferric nitrate nonahydrate, zinc salt, ferric nitrate nonahydrate, cerium salt, zirconium salt, manganese salt, and boehmite; Step S2, spray drying and calcining to obtain an intermediate; Step S3, impregnating and mixing the intermediate with a LiCl / KCl mixed salt solution, drying, and calcining to obtain the energy-saving composite desulfurizing agent. This invention achieves efficient desulfurization and reduced energy consumption with the energy-saving composite desulfurizing agent.

Description

Technical Field

[0001] This invention relates to the field of gas purification technology, specifically to an energy-saving composite desulfurizing agent and its production process. Background Technology

[0002] Existing flue gas or industrial tail gas desulfurization methods mainly include wet methods (such as limestone-gypsum method), semi-dry methods (spray drying absorption), dry injection methods (sodium bicarbonate, quicklime, etc.), and solid adsorption / catalytic oxidation methods (activated coke, activated carbon, metal oxide beds, etc.). These processes generally face challenges in industrial applications due to high energy consumption, material costs, or byproduct treatment: wet systems require circulating slurry, flue gas reheating, or corrosion protection systems, and have high water consumption and pump / fan power consumption; dry / semi-dry methods have limited utilization of alkaline absorbents and high dust loads, often requiring increased reaction temperatures or dosages to meet ultra-low emission requirements; while metal oxide bed desulfurizers have fast reaction rates, the multi-metal active components are difficult to disperse uniformly on the carrier, easily leading to sintering and deactivation during roasting or operation. Furthermore, traditional granulation / extrusion processes have high internal diffusion resistance, resulting in reduced utilization of active sites and increased pressure drop.

[0003] The main defects of the existing technology are: (1) Insufficient SO2 removal efficiency in the low-temperature zone (e.g., the downstream temperature zone of the dust collector / denitrification device), often requiring the flue gas to be heated to maintain the reaction rate, resulting in additional energy consumption; (2) Single active components are not effective against complex flue gas components (O2, H2O, NO). x (3) In the preparation of multi-metal synergistic systems, metal salts and carrier particles are prone to local enrichment, resulting in insufficient contactable active sites and increased material usage. (4) The preparation of some highly active materials depends on high-temperature solid-phase reaction or multiple high-temperature calcination, resulting in high production energy consumption and poor scale-up stability.

[0004] Therefore, there is a need to provide an energy-saving composite desulfurizing agent and its production process to solve the problems existing in the above-mentioned prior art. Summary of the Invention

[0005] In view of this, the present invention provides an energy-saving composite desulfurizing agent and its production process, which can achieve the purpose of efficient desulfurization and reduced energy consumption.

[0006] To achieve the above objectives, the present invention provides a production process for an energy-saving composite desulfurizing agent, comprising the following steps:

[0007] Step S1: Add CTAB to deionized water and stir to dissolve. Add PMMA nanosphere emulsion and continue stirring. Add tannic acid and ferric nitrate nonahydrate and stir to dissolve. Then add zinc salt, ferric nitrate nonahydrate, cerium salt, zirconium salt and manganese salt and stir until dissolved. Add boehmite in batches, disperse ultrasonically, add ammonia water dropwise to adjust pH, age, filter, wash, disperse, and obtain slurry for spray drying.

[0008] Step S2: Spray drying is performed using a spray drying slurry to obtain precursor microsphere powder, which is then calcined in an air atmosphere to obtain an intermediate.

[0009] Step S3: The intermediate is impregnated and mixed with a LiCl / KCl mixed salt solution, dried, and calcined to obtain an energy-saving composite desulfurizing agent.

[0010] Tannic acid and Fe in ferric nitrate nonahydrate 3+ The formation of a polyphenol-metal coordination network and the gradual construction of a coordination layer on the surface of pseudoboehmite and PMMA (polymethyl methacrylate) nanospheres facilitate the provision of a relatively uniform in-situ immobilization and dispersion environment for multi-metal components such as Zn, Fe, Ce, Zr, and Mn. Combined with pH adjustment and aging treatment with ammonia, the metal ions can form multi-metal hydroxyl / oxyhydroxyl precursors more stably, reducing local enrichment, premature precipitation, and agglomeration caused by differences in hydrolysis rates. This is beneficial for improving the dispersion degree, interfacial contact opportunities, and synergistic effects of the active components of the composite oxide after calcination, and provides a better foundation for the adsorption, conversion, and fixation of sulfur oxides in the subsequent desulfurization process.

[0011] The synergistic effect of CTAB, PMMA nanospheres, and spray drying sphericalization facilitates the formation of multi-level porous spherical particles with hollow characteristics. CTAB helps form and connect mesoporous channels, PMMA, after pre-calcination removal, helps leave hollow cavities and larger pores, and spray drying helps obtain microspheres with relatively concentrated particle size distribution, good sphericity, and excellent packing uniformity. This results in a porous structure that combines macroporous mass transfer, mesoporous diffusion, and skeletal support. This structure typically shortens the diffusion path of gases such as SO2 within the particles, reduces mass transfer resistance and bed operating pressure drop, and also considers particle strength, wear resistance, and applicability to fixed-bed packing.

[0012] The use of LiCl / KCl mixed salt impregnation, combined with calcination and subsequent desalting treatment, is beneficial for promoting the formation, adjustment, and dispersion of active components such as Zn-Fe at lower calcination temperatures, and to a certain extent improves the surface state and pore structure of the material. Among them, the mixed salt system can provide favorable conditions for solid-phase diffusion and interface reconstruction during calcination. After washing away soluble salts with water, more unobstructed pores can be obtained and the exposure of active sites can be increased. This is conducive to the synergistic effect between Ce-Zr system, Mn component and Zn / Fe sites, which in turn helps to improve the low-temperature desulfurization performance, sulfur capacity and recycling stability of desulfurizer, while taking into account the energy consumption control and material structure stability of the preparation process.

[0013] Preferably, the solid content of the PMMA nanosphere emulsion is 10-30 wt%; the average particle size of the PMMA nanospheres is 50-500 nm.

[0014] When the PMMA solid content and particle size are within the specified range, it is beneficial to form appropriate hollow cavities and macropore sizes, thereby enabling the desulfurizer to balance diffusion performance, particle strength, and bed pressure drop.

[0015] Preferably, the zinc salt is zinc nitrate hexahydrate, the cerium salt is cerium nitrate hexahydrate, the zircon salt is zirconium oxynitrate, and the manganese salt is manganese nitrate tetrahydrate; the pseudoboehmite is added in 2-6 batches.

[0016] Preferably, the spray drying slurry comprises the following components in parts by weight: 2500 parts deionized water, 5-25 parts CTAB, 110-135 parts PMMA nanosphere emulsion, 1-3 parts tannic acid, 0.8-1.8 parts ferric nitrate nonahydrate, 297-298 parts zinc nitrate hexahydrate, 99-100 parts ferric nitrate nonahydrate, 10-11 parts cerium nitrate hexahydrate, 6.6-6.7 parts zirconium oxynitrate, 3.1-3.2 parts manganese nitrate tetrahydrate, and 100 parts pseudoboehmite.

[0017] Preferably, in step S1, the concentration of ammonia is 20-30 wt%; the aging time is 60-180 min; and the washing is performed 2-5 times with deionized water at 40-80℃.

[0018] It facilitates the hydroxylation deposition of multi-metal components and precursor network rearrangement in a milder and more controllable manner, and promotes the removal of soluble byproducts and residual nitrates; it can reduce the risk of abnormal precipitation, pore blockage and collapse during subsequent calcination, and helps maintain the integrity of particle morphology and the stability of pore structure.

[0019] Preferably, in step S2, the spray drying adopts centrifugal atomization, the rotation speed of the atomizing disc is 10000-14000 rpm, the inlet air temperature is 200-240℃, the outlet air temperature is 100-120℃, and the feed rate is 20-40 mL / min.

[0020] When the atomizing disc rotation speed, inlet and outlet air temperature and feed rate are matched together, the rapid formation of droplets, uniform internal desolvation and complete particle formation can be achieved. This helps the slurry form precursor microspheres with a narrow particle size distribution and high sphericity, which helps to reduce the flow deviation and pressure drop fluctuations during subsequent bed filling and improves the adaptability to engineering applications.

[0021] Preferably, in step S2, the heating rate of calcination is 1-5℃ / min, and the temperature is 300-400℃.

[0022] Preferably, in step S3, the mass ratio of LiCl / KCl is (0.5-1.2):1; and the mass fraction of the mixed salt in the mixed salt solution is 10-30 wt%.

[0023] The LiCl / KCl mixed salt system can provide a suitable ion migration environment, which helps to increase the number of low-temperature active sites and avoids the severe grain growth and pore structure loss caused by simple high-temperature calcination.

[0024] Preferably, in step S3, the drying temperature is 90-130℃ and the time is 3-8h; the calcination heating rate is 1-5℃ / min and the temperature is 450-550℃.

[0025] To achieve the above objectives, the present invention also provides an energy-saving composite desulfurizer prepared by the above-mentioned production process of the energy-saving composite desulfurizer.

[0026] The energy-saving composite desulfurizer prepared using the production process of this invention can achieve efficient desulfurization and reduce energy consumption.

[0027] The above-described technical solution of the present invention has at least the following beneficial effects:

[0028] By combining polyphenol-metal coordination in-situ immobilization, CTAB / PMMA synergistic pore formation, spray drying spherical formation, and LiCl / KCl mixed salt activation-two-stage calcination, spherical microsphere desulfurizers with more uniform active phase dispersion, better pore connectivity, higher mechanical strength, and better low-temperature desulfurization activity can be obtained at a relatively low preparation temperature. This achieves a balance between low-temperature high-efficiency desulfurization, lower bed pressure drop, better hydrothermal stability, and energy-saving effects in both preparation and operation. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0030] Example 1

[0031] Add 2500 mL of deionized water to the reactor, heat to 45 °C and stir. Add 5 g of CTAB (0.2 wt% of the deionized water mass) and dissolve it completely. Then add 120 g of PMMA nanosphere emulsion, in which the emulsion solid content is 18 wt% and the average particle size of PMMA nanospheres is 220 nm. Continue stirring for 30 min. Next, 2.0 g of tannic acid and 1.2 g of ferric nitrate nonahydrate for forming a polyphenol-iron coordination network were added; then 297 g of zinc nitrate hexahydrate, 100 g of ferric nitrate nonahydrate as an active metal source, 10.3 g of cerium nitrate hexahydrate, 6.6 g of zirconium oxynitrate, and 3.1 g of manganese nitrate tetrahydrate were added sequentially and stirred until completely dissolved; finally, 100 g of boehmite (dry basis) was added to the system in two portions and ultrasonically dispersed in a water bath for 28 min. Ammonia solution with a concentration of 24 wt% was added dropwise to adjust the pH of the system to 8.3, and aging was continued for 90 min; after aging, the system was filtered by pressure, and the resulting filter cake was washed three times with deionized water at 55℃. The washed filter cake was added to 750 mL of deionized water and dispersed at 1500 rpm for 30 min to obtain a slurry for spray drying.

[0032] The slurry was spray-dried, with the centrifugal atomizing disc speed controlled at 11200 rpm, the inlet air temperature at 215℃, the outlet air temperature at 108℃, and the feed rate at 20 mL / min, to obtain precursor microsphere powder. The precursor microspheres were placed in an air atmosphere, heated to 340℃ at a rate of 2℃ / min and held at that temperature for 100 min, and then cooled to room temperature to obtain an intermediate.

[0033] The above intermediate was impregnated and mixed with a mixed salt solution of LiCl / KCl mass ratio of 0.9:1 and a mixed salt mass fraction of 18wt%. After impregnation, it was dried at 105℃ for 5 hours. Subsequently, the temperature was increased to 485℃ at 2℃ / min and held for 120 minutes. After cooling, it was washed to remove salt and then dried at 105℃ for 12 hours to obtain an energy-saving composite desulfurizing agent.

[0034] Example 2

[0035] Add 2500 mL of deionized water to the reactor, heat to 45 °C and stir, add 15 g of CTAB (0.6 wt% of the deionized water) and dissolve it; then add 135 g of PMMA nanosphere emulsion, wherein the emulsion solid content is 10 wt% and the average particle size of PMMA nanospheres is 500 nm, and continue stirring for 30 min. Next, 1.0 g of tannic acid and 0.8 g of ferric nitrate nonahydrate for forming a polyphenol-iron coordination network were added; then 298 g of zinc nitrate hexahydrate, 99 g of ferric nitrate nonahydrate as an active metal source, 11 g of cerium nitrate hexahydrate, 6.7 g of zirconium oxynitrate, and 3.2 g of manganese nitrate tetrahydrate were added sequentially and stirred until completely dissolved; finally, 100 g of boehmite (dry basis) was added to the system in four portions, and the mixture was ultrasonically dispersed in a water bath for 32 min. Ammonia solution with a concentration of 22 wt% was added dropwise to adjust the pH of the system to 8.8, and the mixture was aged for another 150 min. After aging, the mixture was filtered by pressure, and the resulting filter cake was washed five times with deionized water at 45 °C. The washed filter cake was added to 800 mL of deionized water and dispersed at 1500 rpm for 30 min to obtain a slurry for spray drying.

[0036] The slurry was spray-dried, with the centrifugal atomizing disc speed controlled at 12000 rpm, the inlet air temperature at 230℃, the outlet air temperature at 110℃, and the feed rate at 28 mL / min, to obtain precursor microsphere powder. The obtained precursor microspheres were placed in an air atmosphere and heated to 360℃ at a rate of 3℃ / min and held at that temperature for 120 min to complete the first stage of calcination.

[0037] The intermediate after the first stage of calcination was impregnated and mixed with a mixed salt solution of LiCl / KCl mass ratio of 0.7:1 and a mixed salt mass fraction of 20wt%. After impregnation, it was dried at 110℃ for 5h. Subsequently, the temperature was increased to 500℃ at 3℃ / min and held for 130min. After cooling, it was washed to remove salt and then dried at 110℃ for 11h to obtain an energy-saving composite desulfurizing agent.

[0038] Example 3

[0039] Add 2500 mL of deionized water to the reactor, heat to 45 °C and stir, add 14 g of CTAB (0.56 wt% of the deionized water) to dissolve it; then add 110 g of PMMA nanosphere emulsion, in which the emulsion solid content is 30 wt% and the average particle size of PMMA nanospheres is 120 nm, and continue stirring for 30 min. Next, 1.4 g of tannic acid and 1.0 g of ferric nitrate nonahydrate for forming a polyphenol-iron coordination network were added; then 297.5 g of zinc nitrate hexahydrate, 99.8 g of ferric nitrate nonahydrate as an active metal source, 10 g of cerium nitrate hexahydrate, 6.6 g of zirconium oxynitrate, and 3.1 g of manganese nitrate tetrahydrate were added sequentially and stirred until completely dissolved; finally, 100 g of boehmite (dry basis) was added to the system in 5 portions, and the mixture was ultrasonically dispersed in a water bath for 20 min. Ammonia solution with a concentration of 20 wt% was added dropwise to adjust the pH of the system to 8.0, and the mixture was aged for another 120 min. After aging, the mixture was filtered by pressure, and the resulting filter cake was washed three times with deionized water at 60 °C. The washed filter cake was added to 700 mL of deionized water and dispersed at 1500 rpm for 30 min to obtain a slurry for spray drying.

[0040] The slurry was spray-dried, with the centrifugal atomizing disc speed controlled at 13000 rpm, the inlet air temperature at 205℃, the outlet air temperature at 112℃, and the feed rate at 24 mL / min, to obtain precursor microsphere powder. The obtained precursor microspheres were placed in an air atmosphere and heated to 380℃ at a rate of 1℃ / min and held at that temperature for 150 min to complete the first stage of calcination.

[0041] The intermediate after the first stage of calcination was impregnated and mixed with a mixed salt solution of LiCl / KCl mass ratio of 1.0:1 and a mixed salt mass fraction of 28 wt%. After impregnation, it was dried at 100℃ for 4 h. Subsequently, the temperature was increased to 470℃ at 4℃ / min and held for 150 min. After cooling, it was washed to remove salt and then dried at 95℃ for 14 h to obtain an energy-saving composite desulfurizing agent.

[0042] Example 4

[0043] Add 2500 mL of deionized water to the reactor, heat to 45 °C and stir. Add 20 g of CTAB (0.8 wt% of the deionized water) and dissolve it. Then add 128 g of PMMA nanosphere emulsion, in which the emulsion solid content is 22 wt% and the average particle size of PMMA nanospheres is 50 nm. Continue stirring for 30 min. Next, 3.0 g of tannic acid and 1.8 g of ferric nitrate nonahydrate for forming a polyphenol-iron coordination network were added; then 298 g of zinc nitrate hexahydrate, 100 g of ferric nitrate nonahydrate as an active metal source, 10.8 g of cerium nitrate hexahydrate, 6.7 g of zirconium oxynitrate, and 3.2 g of manganese nitrate tetrahydrate were added sequentially and stirred until completely dissolved; finally, 100 g of boehmite (dry basis) was added to the system in three portions, and the mixture was ultrasonically dispersed in a water bath for 35 min. Ammonia solution with a concentration of 26 wt% was added dropwise to adjust the pH of the system to 8.5, and the mixture was aged for another 60 min. After aging, the mixture was filtered by pressure, and the resulting filter cake was washed twice with deionized water at 80 °C. The washed filter cake was added to 800 mL of deionized water and dispersed at 1500 rpm for 30 min to obtain a slurry for spray drying.

[0044] The slurry was spray-dried, with the centrifugal atomizing disc speed controlled at 10,000 rpm, the inlet air temperature at 220℃, the outlet air temperature at 100℃, and the feed rate at 30 mL / min, to obtain precursor microsphere powder. The obtained precursor microspheres were placed in an air atmosphere and heated to 300℃ at a rate of 4℃ / min and held at that temperature for 180 min to complete the first stage of calcination.

[0045] The intermediate after the first stage of calcination was impregnated and mixed with a mixed salt solution of LiCl / KCl mass ratio of 1.2:1 and a mixed salt mass fraction of 10wt%. After impregnation, it was dried at 95℃ for 6 hours. Then, the temperature was increased to 520℃ at 1℃ / min and held for 100 minutes. After cooling, it was washed to remove salt and then dried at 120℃ for 8 hours to obtain an energy-saving composite desulfurizing agent.

[0046] Example 5

[0047] Add 2500 mL of deionized water to the reactor, heat to 45 °C and stir, add 25 g of CTAB (1.0 wt% of the deionized water) and dissolve it; then add 118 g of PMMA nanosphere emulsion, in which the emulsion solid content is 16 wt% and the average particle size of PMMA nanospheres is 180 nm, and continue stirring for 30 min. Next, 1.1 g of tannic acid and 0.9 g of ferric nitrate nonahydrate for forming a polyphenol-iron coordination network were added; then 297 g of zinc nitrate hexahydrate, 99 g of ferric nitrate nonahydrate as an active metal source, 10.2 g of cerium nitrate hexahydrate, 6.6 g of zirconium oxynitrate, and 3.1 g of manganese nitrate tetrahydrate were added sequentially and stirred until completely dissolved; finally, 100 g of boehmite (dry basis) was added to the system in 6 portions, and the mixture was ultrasonically dispersed in a water bath for 24 min. Ammonia solution with a concentration of 28 wt% was added dropwise to adjust the pH of the system to 9.0, and the mixture was aged for another 105 min. After aging, the mixture was filtered by pressure, and the resulting filter cake was washed four times with deionized water at 70 °C. The washed filter cake was then added to 700 mL of deionized water and dispersed at 1500 rpm for 30 min to obtain a slurry for spray drying.

[0048] The slurry was spray-dried, with the centrifugal atomizing disc speed controlled at 13800 rpm, the inlet air temperature at 240℃, the outlet air temperature at 115℃, and the feed rate at 22 mL / min, to obtain precursor microsphere powder. The obtained precursor microspheres were placed in an air atmosphere and heated to 330℃ at a rate of 5℃ / min and held at that temperature for 90 min to complete the first stage of calcination.

[0049] The intermediate after the first stage of calcination was impregnated and mixed with a mixed salt solution of LiCl / KCl mass ratio of 0.5:1 and a mixed salt mass fraction of 24wt%. After impregnation, it was dried at 125℃ for 3 hours. Subsequently, the temperature was increased to 450℃ at 5℃ / min and held for 180 minutes. After cooling, it was washed to remove salt and then dried at 130℃ for 10 hours to obtain an energy-saving composite desulfurizing agent.

[0050] Example 6

[0051] Add 2500 mL of deionized water to the reactor, heat to 45 °C and stir, add 12 g of CTAB (0.48 wt% of the deionized water) to dissolve it; then add 130 g of PMMA nanosphere emulsion, in which the emulsion solid content is 14 wt% and the average particle size of PMMA nanospheres is 400 nm, and continue stirring for 30 min. Next, 2.6 g of tannic acid and 1.6 g of ferric nitrate nonahydrate for forming a polyphenol-iron coordination network were added; then, 297.8 g of zinc nitrate hexahydrate, 100 g of ferric nitrate nonahydrate as an active metal source, 10.9 g of cerium nitrate hexahydrate, 6.7 g of zirconium oxynitrate, and 3.2 g of manganese nitrate tetrahydrate were added sequentially and stirred until completely dissolved; finally, 100 g of boehmite (dry basis) was added to the system in 5 portions, and the mixture was ultrasonically dispersed in a water bath for 40 min. Ammonia solution with a concentration of 30 wt% was added dropwise to adjust the pH of the system to 8.4, and the mixture was aged for another 180 min. After aging, the mixture was filtered by pressure, and the resulting filter cake was washed four times with deionized water at 40 °C. The washed filter cake was added to 825 mL of deionized water and dispersed at 1500 rpm for 30 min to obtain a slurry for spray drying.

[0052] The slurry was spray-dried, with the centrifugal atomizing disc speed controlled at 14000 rpm, the inlet air temperature at 200℃, the outlet air temperature at 120℃, and the feed rate at 40 mL / min, to obtain precursor microsphere powder. The obtained precursor microspheres were placed in an air atmosphere and heated to 400℃ at a rate of 2℃ / min and held for 60 min to complete the first stage of calcination.

[0053] The intermediate after the first stage of calcination was impregnated and mixed with a mixed salt solution of 30 wt% (LiCl / KCl mass ratio of 0.8:1). After impregnation, it was dried at 130℃ for 8 h. Subsequently, the temperature was increased to 550℃ at 2℃ / min and held for 60 min. After cooling, it was washed to remove salt and then dried at 90℃ for 16 h to obtain an energy-saving composite desulfurizing agent.

[0054] Example 7

[0055] Add 2500 mL of deionized water to the reactor, heat to 45 °C and stir, add 18 g of CTAB (0.72 wt% of the deionized water) to dissolve it; then add 125 g of PMMA nanosphere emulsion, in which the emulsion solid content is 26 wt% and the average particle size of PMMA nanospheres is 320 nm, and continue stirring for 30 min. Next, 1.8 g of tannic acid and 1.4 g of ferric nitrate nonahydrate for forming a polyphenol-iron coordination network were added; then 297.2 g of zinc nitrate hexahydrate, 99.6 g of ferric nitrate nonahydrate as an active metal source, 10.5 g of cerium nitrate hexahydrate, 6.6 g of zirconium oxynitrate, and 3.1 g of manganese nitrate tetrahydrate were added sequentially and stirred until completely dissolved; finally, 100 g of boehmite (dry basis) was added to the system in four portions, and the mixture was ultrasonically dispersed in a water bath for 30 min. Ammonia solution with a concentration of 25 wt% was added dropwise to adjust the pH of the system to 8.7, and the mixture was aged for another 135 min. After aging, the mixture was filtered by pressure, and the resulting filter cake was washed three times with deionized water at 65 °C. The washed filter cake was added to 750 mL of deionized water and dispersed at 1500 rpm for 30 min to obtain a slurry for spray drying.

[0056] The slurry was spray-dried, with the centrifugal atomizing disc speed controlled at 12600 rpm, the inlet air temperature at 235℃, the outlet air temperature at 105℃, and the feed rate at 36 mL / min, to obtain precursor microsphere powder. The obtained precursor microspheres were placed in an air atmosphere and heated to 390℃ at a rate of 3℃ / min and held at that temperature for 140 min to complete the first stage of calcination.

[0057] The intermediate after the first stage of calcination was impregnated and mixed with a mixed salt solution of LiCl / KCl mass ratio of 1.1:1 and a mixed salt mass fraction of 16wt%. After impregnation, it was dried at 90℃ for 7 hours. Subsequently, the temperature was increased to 540℃ at 3℃ / min and held for 90 minutes. After cooling, it was washed to remove salt and then dried at 100℃ for 13 hours to obtain an energy-saving composite desulfurizing agent.

[0058] The present invention also includes comparative examples and related experiments.

[0059] Comparative Example 1

[0060] The only difference between Comparative Example 1 and Example 1 is that tannic acid and ferric nitrate nonahydrate are not added. The other components and production process are the same as in Example 1, and an energy-saving composite desulfurizer is prepared.

[0061] Comparative Example 2

[0062] The difference between Comparative Example 2 and Example 1 is that PMMA nanosphere emulsion was not added, but the other components and production process were the same as in Example 1, and an energy-saving composite desulfurizer was prepared.

[0063] Comparative Example 3

[0064] The difference between Comparative Example 3 and Example 1 is that LiCl / KCl mixed salt impregnation and activation were not performed, while the other components and production process were the same as in Example 1, and an energy-saving composite desulfurizer was prepared.

[0065] Performance testing

[0066] (1) Low-temperature desulfurization performance test

[0067] The samples obtained from Examples 1-7 and Comparative Examples 1-3 were crushed and sieved to a size of 0.5-1.0 mm, and then packed into a quartz fixed-bed reactor at a loading volume of 10 mL, maintaining a consistent bed height. Simulated flue gas was prepared using N2 as the balancing gas, with the following composition: SO2 volume fraction of 2000 × 10⁻⁶. -6 The volume fraction of O2 is 6 vol%, the volume fraction of H2O is 8 vol%, and the balance is N2; the volume hourly space velocity is controlled at 6000 h⁻¹. -1 The test temperature was 150℃. The inlet and outlet SO2 concentrations were recorded, and the initial SO2 removal rate, the average removal rate over 120 minutes, and the breakthrough time were calculated. Breakthrough was defined as the outlet SO2 concentration reaching 10% of the inlet concentration. Sulfur capacity was calculated as the amount of sulfur absorbed per unit mass of sample, based on the cumulative SO2 removed before breakthrough. The test results are shown in Table 1.

[0068] Table 1. Test results of low-temperature desulfurization performance

[0069]

[0070] As shown in Table 1 above, the energy-saving composite desulfurizer prepared in Comparative Example 1, compared with Example 1, exhibits significantly lower initial SO2 removal rate, average removal rate over 120 minutes, breakthrough time, and sulfur capacity. This indicates that the tannic acid-Fe 3+ The coordination network is beneficial to enhancing the effective action of the active components, thereby improving the desulfurization reaction efficiency and enhancing the low-temperature desulfurization performance. Compared with Example 1, the energy-saving composite desulfurizer prepared in Comparative Example 2 also showed a significant decrease in various desulfurization performance characteristics, indicating that the synergistic pore formation of PMMA nanosphere emulsion and CTAB helps to form a hollow hierarchical porous structure, reducing diffusion resistance, thereby improving the contact efficiency between the reactant gas and the active sites, and enhancing the desulfurization rate and sulfur capacity. Compared with Example 1, the energy-saving composite desulfurizer prepared in Comparative Example 3 showed varying degrees of decrease in initial SO2 removal rate, average removal rate at 120 min, breakthrough time, and sulfur capacity, indicating that LiCl / KCl mixed salt wetting and activation helps to increase the number of low-temperature active sites, thereby further improving desulfurization efficiency and sulfur absorption capacity. The test results of Examples 1-7 show that the energy-saving composite desulfurizers prepared by this scheme all have superior low-temperature desulfurization performance, demonstrating that the present invention can achieve the goal of efficient desulfurization and reduced energy consumption.

[0071] (2) Structural and bed performance testing

[0072] The specific surface area and total pore volume of the samples were tested using the nitrogen adsorption-desorption method; the compressive strength of a single particle was determined using a particle strength tester, with 20 particles tested in parallel for each sample and the average value taken; under the same particle size and packing conditions as the low-temperature desulfurization test, N2 with an apparent gas velocity of 0.8 m / s was introduced, and the bed pressure drop was measured. The test results are shown in Table 2.

[0073] Table 2. Test results of structure and bed performance

[0074]

[0075] As shown in Table 2 above, compared with Example 1, the energy-saving composite desulfurizer prepared in Comparative Example 1 has a lower specific surface area, total pore volume, and single-particle compressive strength, and a higher bed pressure drop, indicating that tannic acid-Fe 3+ Coordination networks help suppress the migration and local enrichment of polymetallic salts during drying and calcination, reducing agglomeration and pore blockage, thereby improving the structural uniformity of the material while maintaining particle strength. Compared with Example 1, the energy-saving composite desulfurizer prepared in Comparative Example 2 has a significantly reduced total pore volume and a significantly increased bed pressure drop, indicating that the synergistic pore-forming effect of PMMA nanosphere emulsion and CTAB can promote the formation of interconnected mesopores and hollow / macropore structures, thereby reducing bed mass transfer resistance and improving filling performance. Compared with Example 1, the energy-saving composite desulfurizer prepared in Comparative Example 3 has a certain degree of decrease in specific surface area, total pore volume, and single-particle compressive strength, indicating that LiCl / KCl mixed salt wetting and activation helps to inhibit grain growth and reduce pore structure loss while increasing active sites.

[0076] (3) Hydrothermal aging stability test

[0077] The samples obtained in Examples 1-7 and Comparative Examples 1-3 were aged continuously at 160°C for 12 hours in an N2 atmosphere containing 10 vol% H2O and 6 vol% O2. After aging, the tests were repeated under the same conditions as the low-temperature desulfurization performance test. The initial SO2 removal rate and breakthrough time after aging were recorded, and the sulfur capacity retention rate was calculated. The test results are shown in Table 3.

[0078] Table 3 Results of hydrothermal aging stability test

[0079]

[0080] As shown in Table 3, compared with Example 1, the initial SO2 removal rate, breakthrough time, and sulfur capacity retention rate of the desulfurizer prepared in Comparative Example 1 after aging were only 82.6%, 101 min, and 80.0%, respectively, which were significantly lower than those of Example 1 (92.1%, 133 min, and 86.9%). This indicates that the desulfurization rate of tannic acid-Fe 3+ The coordination system helps improve the activity retention of the desulfurizer under hydrothermal conditions. Compared with Example 1, the initial SO2 removal rate, breakthrough time and sulfur capacity retention rate of the desulfurizer prepared in Comparative Example 2 after aging were 84.1%, 109 min and 80.8% respectively, which were significantly different from Example 1. This indicates that the hierarchical porous structure helps to alleviate the problems of pore blockage and mass transfer limitation during aging, thereby improving the hydrothermal stability of the desulfurizer. Compared with Example 1, the energy-saving composite desulfurizer prepared in Comparative Example 3 also showed a decrease in the initial SO2 removal rate, breakthrough time and sulfur capacity retention rate after aging. This indicates that LiCl / KCl mixed salt wetting and activation helps to improve the stability of active sites and slow down aging deactivation.

[0081] The above are preferred embodiments of the present invention. Those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A production process for an energy-saving composite desulfurizing agent, characterized in that, Includes the following steps: Step S1: Add CTAB to deionized water and stir to dissolve. Add PMMA nanosphere emulsion and continue stirring. Add tannic acid and ferric nitrate nonahydrate and stir to dissolve. Then add zinc salt, ferric nitrate nonahydrate, cerium salt, zirconium salt and manganese salt and stir until dissolved. Add boehmite in batches, disperse ultrasonically, add ammonia water dropwise to adjust pH, age, filter, wash, disperse, and obtain slurry for spray drying. Step S2: Spray drying is performed using a spray drying slurry to obtain precursor microsphere powder, which is then calcined in air to obtain an intermediate; the calcination heating rate is 1-5℃ / min, and the temperature is 300-400℃. Step S3: The intermediate is impregnated and mixed with a LiCl / KCl mixed salt solution, dried, and calcined to obtain an energy-saving composite desulfurizer; the calcination heating rate is 1-5℃ / min, and the temperature is 450-550℃.

2. The production process of an energy-saving composite desulfurizing agent according to claim 1, characterized in that, The PMMA nanosphere emulsion has a solid content of 10-30 wt% and an average particle size of 50-500 nm.

3. The production process of an energy-saving composite desulfurizing agent according to claim 1, characterized in that, The zinc salt is zinc nitrate hexahydrate, the cerium salt is cerium nitrate hexahydrate, the zircon salt is zirconium oxynitrate, and the manganese salt is manganese nitrate tetrahydrate; boehmite is added in 2-6 batches.

4. The production process of an energy-saving composite desulfurizing agent according to claim 1, characterized in that, The spray-drying slurry comprises the following components in parts by weight: 2500 parts deionized water, 5-25 parts CTAB, 110-135 parts PMMA nanosphere emulsion, 1-3 parts tannic acid, 0.8-1.8 parts ferric nitrate nonahydrate, 297-298 parts zinc nitrate hexahydrate, 99-100 parts ferric nitrate nonahydrate, 10-11 parts cerium nitrate hexahydrate, 6.6-6.7 parts zirconium oxynitrate, 3.1-3.2 parts manganese nitrate tetrahydrate, and 100 parts pseudoboehmite.

5. The production process of an energy-saving composite desulfurizing agent according to claim 1, characterized in that, In step S1, the concentration of ammonia is 20-30 wt%; the aging time is 60-180 min; and the washing is performed 2-5 times with deionized water at 40-80℃.

6. The production process of an energy-saving composite desulfurizing agent according to claim 1, characterized in that, In step S2, the spray drying adopts centrifugal atomization, the rotation speed of the atomizing disc is 10000-14000 rpm, the inlet air temperature is 200-240℃, the outlet air temperature is 100-120℃, and the feed rate is 20-40 mL / min.

7. The production process of an energy-saving composite desulfurizing agent according to claim 1, characterized in that, In step S3, the mass ratio of LiCl / KCl is (0.5-1.2):1; the mass fraction of the mixed salt in the mixed salt solution is 10-30 wt%.

8. The production process of an energy-saving composite desulfurizing agent according to claim 1, characterized in that, In step S3, the drying temperature is 90-130℃ and the time is 3-8 hours.

9. An energy-saving composite desulfurizing agent, characterized in that, It is prepared using the production process of an energy-saving composite desulfurizer as described in any one of claims 1-8.

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