Preparation method of high-pore-volume calcium-based particulate desulfurizer

Abstract

The present application relates to the technical field of desulfurizer, and particularly relates to a preparation method of high-pore-volume calcium-based granular desulfurizer. The method comprises the following steps: (1) preparing carboxymethyl cellulose loaded with calcium carbonate; (2) modifying the cellulose by polyethylene glycol grafting; (3) introducing zinc acetate solution to prepare modified cellulose; (4) mixing calcium carbonate powder, modified cellulose and the like to prepare slurry; (5) adopting fluidized bed granulation to form granules; and (6) preparing high-pore-volume calcium-based desulfurizer under optimized calcination process. The desulfurizer is modified by cellulose functionalization, polyethylene glycol grafting and zinc ion introduction to optimize pore structure and enhance mechanical strength, and finally the desulfurizer with high pore volume, high mechanical strength and excellent cycle stability is obtained, which is suitable for removal of hydrogen sulfide in industrial waste gas and natural gas, and has good industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of desulfurizing agent technology, and in particular to a method for preparing a high-porosity calcium-based particulate desulfurizing agent. Background Technology

[0002] With the acceleration of industrialization, the widespread use of fossil fuels has led to increasingly serious sulfide pollution problems. Hydrogen sulfide (H2S), a common sulfur-containing compound, is not only highly corrosive and toxic, but also poses a serious threat to the environment and human health. Therefore, how to efficiently remove hydrogen sulfide from industrial waste gas and natural gas has become an important research topic in the fields of environmental protection and energy purification. Calcium-based desulfurizers have attracted much attention due to their abundant resources, low cost, and excellent environmental performance. However, traditional calcium-based desulfurizers have many problems in practical applications, such as insufficiently developed pore structure, inadequate mechanical strength, and poor recyclability, which limit their widespread application in industry.

[0003] Currently, calcium-based desulfurizers are mainly prepared through physical mixing, chemical modification, and high-temperature calcination. Traditional preparation methods typically use a single calcium-based compound as a raw material, and produce the desulfurizer through simple granulation and calcination processes. However, calcium-based desulfurizers prepared by this method often suffer from low pore volume and limited specific surface area, making it difficult to meet the requirements for efficient hydrogen sulfide adsorption. Furthermore, calcium-based desulfurizers are prone to particle breakage and pore collapse during use, leading to a significant decrease in mechanical strength and cycle stability. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for preparing a high-porosity calcium-based particulate desulfurizer, so as to provide a calcium-based desulfurizer with high porosity, high mechanical strength and excellent cycle stability.

[0005] To achieve the above objectives, the present invention provides a method for preparing a high-porosity calcium-based particulate desulfurizer, comprising the following steps:

[0006] (1) Add calcium chloride and sodium carboxymethyl cellulose to deionized water, stir at room temperature for 50-70 min, then add sodium carbonate aqueous solution with a concentration of 8-12 wt%, stir at room temperature for 20-40 min, purify, and obtain carboxymethyl cellulose loaded with calcium carbonate.

[0007] (2) Add carboxymethyl cellulose loaded with calcium carbonate to cyclohexane, stir for 15-25 min, then add polyethylene glycol monomethyl ether and p-toluenesulfonic acid, heat to 80-90℃, reflux and stir for 5-7 h, purify to obtain polyethylene glycol grafted cellulose.

[0008] (3) Polyethylene glycol grafted cellulose was added to a 4-6 wt% zinc acetate aqueous solution, stirred at room temperature for 60-84 h, and purified to obtain modified cellulose;

[0009] (4) Add calcium carbonate powder, modified cellulose and sodium carboxymethyl cellulose to deionized water and stir for 10-20 minutes to obtain a slurry;

[0010] (5) The slurry is granulated by fluidized bed to obtain particles with a particle size D50 of 1.3-1.8 mm;

[0011] (6) The microparticles are placed in a muffle furnace and calcined to obtain a high-porosity calcium-based desulfurizer.

[0012] Preferably, the degree of substitution of sodium carboxymethyl cellulose in step (1) is 0.8-0.9.

[0013] Preferably, in step (1), the weight ratio of calcium chloride, sodium carboxymethyl cellulose, deionized water and sodium carbonate aqueous solution is 30-50:120-180:1000-1500:400-600.

[0014] Preferably, in step (2), the weight ratio of carboxymethyl cellulose loaded with calcium carbonate, cyclohexane, polyethylene glycol monomethyl ether, and p-toluenesulfonic acid is 120-180:600-1000:40-60:5-10.

[0015] Preferably, the weight-average molecular weight of polyethylene glycol monomethyl ether in step (2) is 3000-5000.

[0016] Preferably, in step (3), the weight ratio of polyethylene glycol grafted cellulose to zinc acetate aqueous solution is 150-250:300-800.

[0017] Preferably, in step (4), the weight ratio of calcium carbonate powder, modified cellulose, sodium carboxymethyl cellulose and deionized water is 300-500:80-120:8-12:150-250.

[0018] Preferably, the calcium carbonate powder in step (4) has a mesh size of 200-400.

[0019] Preferably, in step (5), the nozzle diameter of the fluidized bed granulation is 0.7-0.9 mm, the fluidizing gas velocity is 0.6-1 m / s, the inlet air temperature is 55-65℃, the outlet air temperature is 35-40℃, the atomization pressure is 0.2-0.3 MPa, and the bottom spray height is 80-120 mm.

[0020] Preferably, in step (6), the calcination is carried out in a nitrogen atmosphere, with the temperature increased to 430-480°C at a rate of 4-6°C / min and held for 0.8-1.2h, then increased to 830-880°C at a rate of 1-3°C / min and held for 1.5-2.5h, followed by cooling down in the furnace.

[0021] The beneficial effects of this invention are:

[0022] This invention utilizes a composite modification of cellulose and calcium-based compounds, combined with an optimized calcination process, to prepare a calcium-based desulfurizer exhibiting high pore volume, high mechanical strength, and excellent cycle stability. This desulfurizer demonstrates significant advantages in several aspects. First, through functionalization of cellulose and loading with calcium-based compounds, a porous material with a rich pore structure is formed after calcination. The introduction of this porous structure not only significantly increases the specific surface area of ​​the material but also provides more active sites for the adsorption and reaction of hydrogen sulfide, thereby enhancing the adsorption capacity and reactivity of the desulfurizer.

[0023] Secondly, this invention further optimizes the pore structure and framework stability of the material through polyethylene glycol grafting modification. During calcination, polyethylene glycol undergoes thermal decomposition and cross-linking reactions to form a stable pore network structure, while simultaneously introducing more active sites onto the material surface, significantly improving the overall performance of the desulfurizer. Furthermore, the polyethylene glycol grafting method exhibits higher stability compared to physical mixing, effectively avoiding pore structure inhomogeneity and migration during calcination, thereby further enhancing the porosity and stability of the material.

[0024] Furthermore, this invention, through the introduction of zinc ions, forms a composite interface during high-temperature calcination, further enhancing the material's mechanical strength and cycle stability. The coordination structure of zinc ions transforms into a composite interface at high temperatures, creating a "pinning effect" that significantly improves the compressive strength of the particles. Simultaneously, zinc ions also promote the graphitization transformation of the carbon layers in the framework, thereby further enhancing the material's mechanical properties. This optimized structural design results in minimal performance degradation of the desulfurizer during multiple desulfurization-regeneration cycles, exhibiting excellent stability.

[0025] In summary, the calcium-based desulfurizer prepared by this invention exhibits significant advantages in desulfurization efficiency, mechanical strength, and cycle stability, and has broad prospects for industrial application. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0027] Example 1:

[0028] (1) Add 30g of calcium chloride and 120g of sodium carboxymethyl cellulose (degree of substitution 0.85) to 1000g of deionized water, stir at room temperature for 50min, then add 400g of sodium carbonate aqueous solution with a concentration of 8wt%, stir at room temperature for 20min, centrifuge, wash with deionized water 3 times, and vacuum dry to obtain calcium carbonate-loaded carboxymethyl cellulose.

[0029] (2) Add 120g of calcium carbonate-loaded carboxymethyl cellulose to 600g of cyclohexane, stir for 15min, then add 40g of polyethylene glycol monomethyl ether (weight average molecular weight of 3000) and 5g of p-toluenesulfonic acid, heat to 80℃, reflux and stir for 5h, cool down, centrifuge, wash with ethanol 3 times, and vacuum dry to obtain polyethylene glycol grafted cellulose.

[0030] (3) Add 150g of polyethylene glycol grafted cellulose to 300g of 4wt% zinc acetate aqueous solution, stir at room temperature for 60h, centrifuge, wash with deionized water 3 times, and vacuum dry to obtain modified cellulose.

[0031] (4) Add 300g of calcium carbonate powder (325 mesh), 80g of modified cellulose and 8g of sodium carboxymethyl cellulose to 150g of deionized water and stir at 250rpm for 10min to obtain a slurry.

[0032] (5) The slurry was granulated by fluidized bed with a nozzle diameter of 0.7 mm, a fluidizing gas velocity of 0.6 m / s, an inlet air temperature of 55 ℃, an outlet air temperature of 35 ℃, an atomization pressure of 0.2 MPa, and a bottom spray height of 80 mm to obtain particles with a particle size D50 of 1.3 mm.

[0033] (6) The particles were placed in a muffle furnace and heated to 430°C at a rate of 4°C / min under a nitrogen atmosphere. The temperature was held for 0.8 h, then increased to 830°C at a rate of 1°C / min and held for 1.5 h. The temperature was then lowered with the furnace to obtain a high-porosity calcium-based desulfurizer.

[0034] Example 2:

[0035] (1) Add 40g of calcium chloride and 150g of sodium carboxymethyl cellulose (degree of substitution 0.85) to 1200g of deionized water, stir at room temperature for 60min, then add 500g of sodium carbonate aqueous solution with a concentration of 10wt%, stir at room temperature for 30min, centrifuge, wash 3 times with deionized water, and vacuum dry to obtain calcium carbonate-loaded carboxymethyl cellulose.

[0036] (2) Add 150g of calcium carbonate-loaded carboxymethyl cellulose to 800g of cyclohexane, stir for 20min, then add 50g of polyethylene glycol monomethyl ether (weight average molecular weight of 4000) and 7.5g of p-toluenesulfonic acid, heat to 85℃, reflux and stir for 6h, cool, centrifuge, wash 3 times with ethanol, and vacuum dry to obtain polyethylene glycol grafted cellulose;

[0037] (3) Add 200g of polyethylene glycol grafted cellulose to 500g of 5wt% zinc acetate aqueous solution, stir at room temperature for 72h, centrifuge, wash with deionized water 3 times, and vacuum dry to obtain modified cellulose.

[0038] (4) Add 400g of calcium carbonate powder (325 mesh), 100g of modified cellulose and 10g of sodium carboxymethyl cellulose to 200g of deionized water and stir at 300rpm for 15min to obtain a slurry.

[0039] (5) The slurry was granulated by fluidized bed with a nozzle diameter of 0.8 mm, a fluidizing gas velocity of 0.8 m / s, an inlet air temperature of 60 ℃, an outlet air temperature of 38 ℃, an atomization pressure of 0.25 MPa, and a bottom spray height of 100 mm to obtain particles with a particle size D50 of 1.5 mm.

[0040] (6) The particles are placed in a muffle furnace and heated to 450°C at a rate of 5°C / min under a nitrogen atmosphere. The temperature is held for 1 hour, then heated to 850°C at a rate of 2°C / min and held for 2 hours. The temperature is then lowered with the furnace to obtain a high-porosity calcium-based desulfurizer.

[0041] Example 3:

[0042] (1) Add 50g of calcium chloride and 180g of sodium carboxymethyl cellulose (degree of substitution 0.85) to 1500g of deionized water, stir at room temperature for 70min, then add 600g of sodium carbonate aqueous solution with a concentration of 12wt%, stir at room temperature for 40min, centrifuge, wash with deionized water 3 times, and vacuum dry to obtain calcium carbonate-loaded carboxymethyl cellulose.

[0043] (2) Add 180g of calcium carbonate-loaded carboxymethyl cellulose to 1000g of cyclohexane, stir for 25min, then add 60g of polyethylene glycol monomethyl ether (weight average molecular weight of 5000) and 10g of p-toluenesulfonic acid, heat to 90℃, reflux and stir for 7h, cool down, centrifuge, wash 3 times with ethanol, and vacuum dry to obtain polyethylene glycol grafted cellulose.

[0044] (3) Add 250g of polyethylene glycol grafted cellulose to 800g of 6wt% zinc acetate aqueous solution, stir at room temperature for 84h, centrifuge, wash with deionized water 3 times, and vacuum dry to obtain modified cellulose.

[0045] (4) Add 500g of calcium carbonate powder (325 mesh), 120g of modified cellulose and 12g of sodium carboxymethyl cellulose to 250g of deionized water and stir at 350rpm for 20min to obtain a slurry.

[0046] (5) The slurry was granulated by fluidized bed with a nozzle diameter of 0.9 mm, a fluidizing gas velocity of 1 m / s, an inlet air temperature of 65 ℃, an outlet air temperature of 40 ℃, an atomization pressure of 0.3 MPa, and a bottom spray height of 120 mm to obtain particles with a particle size D50 of 1.8 mm.

[0047] (6) The particles were placed in a muffle furnace and heated to 480°C at a rate of 6°C / min under a nitrogen atmosphere. The temperature was held for 1.2 h, then increased to 880°C at a rate of 3°C / min and held for 2.5 h. The temperature was then lowered with the furnace to obtain a high-porosity calcium-based desulfurizer.

[0048] Comparative Example 1:

[0049] The difference between Comparative Example 1 and Example 2 is that the calcium carbonate-loaded carboxymethyl cellulose in step (2) is replaced with sodium carboxymethyl cellulose (degree of substitution 0.85);

[0050] The specific steps are as follows:

[0051] (1) Add 150g sodium carboxymethyl cellulose (degree of substitution 0.85) to 800g cyclohexane, stir for 20min, then add 50g polyethylene glycol monomethyl ether (weight average molecular weight 4000) and 7.5g p-toluenesulfonic acid, heat to 85℃, reflux and stir for 6h, cool, centrifuge, wash 3 times with ethanol, and vacuum dry to obtain polyethylene glycol grafted cellulose;

[0052] (2) Add 200g of polyethylene glycol grafted cellulose to 500g of 5wt% zinc acetate aqueous solution, stir at room temperature for 72h, centrifuge, wash with deionized water 3 times, and vacuum dry to obtain modified cellulose.

[0053] (3) Add 400g of calcium carbonate powder (325 mesh), 100g of modified cellulose and 10g of sodium carboxymethyl cellulose to 200g of deionized water and stir at 300rpm for 15min to obtain a slurry.

[0054] (4) The slurry was granulated by fluidized bed with a nozzle diameter of 0.8 mm, a fluidizing gas velocity of 0.8 m / s, an inlet air temperature of 60 ℃, an outlet air temperature of 38 ℃, an atomization pressure of 0.25 MPa, and a bottom spray height of 100 mm to obtain particles with a particle size D50 of 1.5 mm.

[0055] (5) The particles are placed in a muffle furnace and heated to 450°C at a rate of 5°C / min under a nitrogen atmosphere. The temperature is held for 1 hour, then heated to 850°C at a rate of 2°C / min and held for 2 hours. The temperature is then lowered with the furnace to obtain a calcium-based desulfurizer.

[0056] Comparative Example 2:

[0057] The difference between Comparative Example 2 and Example 2 is that the polyethylene glycol grafted cellulose in step (3) is replaced with carboxymethyl cellulose loaded with calcium carbonate;

[0058] The specific steps are as follows:

[0059] (1) Add 40g of calcium chloride and 150g of sodium carboxymethyl cellulose (degree of substitution 0.85) to 1200g of deionized water, stir at room temperature for 60min, then add 500g of sodium carbonate aqueous solution with a concentration of 10wt%, stir at room temperature for 30min, centrifuge, wash 3 times with deionized water, and vacuum dry to obtain calcium carbonate-loaded carboxymethyl cellulose.

[0060] (2) 200g of calcium carbonate-loaded carboxymethyl cellulose was added to 500g of 5wt% zinc acetate aqueous solution, stirred at room temperature for 72h, centrifuged, washed 3 times with deionized water, and vacuum dried to obtain modified cellulose.

[0061] (3) Add 400g of calcium carbonate powder (325 mesh), 100g of modified cellulose and 10g of sodium carboxymethyl cellulose to 200g of deionized water and stir at 300rpm for 15min to obtain a slurry.

[0062] (4) The slurry was granulated by fluidized bed with a nozzle diameter of 0.8 mm, a fluidizing gas velocity of 0.8 m / s, an inlet air temperature of 60 ℃, an outlet air temperature of 38 ℃, an atomization pressure of 0.25 MPa, and a bottom spray height of 100 mm to obtain particles with a particle size D50 of 1.5 mm.

[0063] (5) The particles are placed in a muffle furnace and heated to 450°C at a rate of 5°C / min under a nitrogen atmosphere. The temperature is held for 1 hour, then heated to 850°C at a rate of 2°C / min and held for 2 hours. The temperature is then lowered with the furnace to obtain a calcium-based desulfurizer.

[0064] Comparative Example 3:

[0065] The difference between Comparative Example 3 and Example 2 is that the modified cellulose in step (4) is replaced with polyethylene glycol grafted cellulose;

[0066] The specific steps are as follows:

[0067] (1) Add 40g of calcium chloride and 150g of sodium carboxymethyl cellulose (degree of substitution 0.85) to 1200g of deionized water, stir at room temperature for 60min, then add 500g of sodium carbonate aqueous solution with a concentration of 10wt%, stir at room temperature for 30min, centrifuge, wash 3 times with deionized water, and vacuum dry to obtain calcium carbonate-loaded carboxymethyl cellulose.

[0068] (2) Add 150g of calcium carbonate-loaded carboxymethyl cellulose to 800g of cyclohexane, stir for 20min, then add 50g of polyethylene glycol monomethyl ether (weight average molecular weight of 4000) and 7.5g of p-toluenesulfonic acid, heat to 85℃, reflux and stir for 6h, cool, centrifuge, wash 3 times with ethanol, and vacuum dry to obtain polyethylene glycol grafted cellulose;

[0069] (3) Add 400g of calcium carbonate powder (325 mesh), 100g of polyethylene glycol grafted cellulose and 10g of sodium carboxymethyl cellulose to 200g of deionized water and stir at 300rpm for 15min to obtain a slurry.

[0070] (4) The slurry was granulated by fluidized bed with a nozzle diameter of 0.8 mm, a fluidizing gas velocity of 0.8 m / s, an inlet air temperature of 60 ℃, an outlet air temperature of 38 ℃, an atomization pressure of 0.25 MPa, and a bottom spray height of 100 mm to obtain particles with a particle size D50 of 1.5 mm.

[0071] (5) The particles are placed in a muffle furnace and heated to 450°C at a rate of 5°C / min under a nitrogen atmosphere. The temperature is held for 1 hour, then heated to 850°C at a rate of 2°C / min and held for 2 hours. The temperature is then lowered with the furnace to obtain a calcium-based desulfurizer.

[0072] Comparative Example 4:

[0073] The difference between Comparative Example 4 and Example 2 is that: the polyethylene glycol grafted cellulose in step (3) is replaced with carboxymethyl cellulose loaded with calcium carbonate; the amount of modified cellulose added in step (4) is modified to 75g, and 25g of polyethylene glycol (weight average molecular weight of 4000) is added.

[0074] The specific steps are as follows:

[0075] (1) Add 40g of calcium chloride and 150g of sodium carboxymethyl cellulose (degree of substitution 0.85) to 1200g of deionized water, stir at room temperature for 60min, then add 500g of sodium carbonate aqueous solution with a concentration of 10wt%, stir at room temperature for 30min, centrifuge, wash 3 times with deionized water, and vacuum dry to obtain calcium carbonate-loaded carboxymethyl cellulose.

[0076] (2) 200g of calcium carbonate-loaded carboxymethyl cellulose was added to 500g of 5wt% zinc acetate aqueous solution, stirred at room temperature for 72h, centrifuged, washed 3 times with deionized water, and vacuum dried to obtain modified cellulose.

[0077] (3) Add 400g of calcium carbonate powder (325 mesh), 75g of modified cellulose, 25g of polyethylene glycol (weight average molecular weight of 4000) and 10g of sodium carboxymethyl cellulose to 200g of deionized water and stir at 300rpm for 15min to obtain a slurry.

[0078] (4) The slurry was granulated by fluidized bed with a nozzle diameter of 0.8 mm, a fluidizing gas velocity of 0.8 m / s, an inlet air temperature of 60 ℃, an outlet air temperature of 38 ℃, an atomization pressure of 0.25 MPa, and a bottom spray height of 100 mm to obtain particles with a particle size D50 of 1.5 mm.

[0079] (5) The particles are placed in a muffle furnace and heated to 450°C at a rate of 5°C / min under a nitrogen atmosphere. The temperature is held for 1 hour, then heated to 850°C at a rate of 2°C / min and held for 2 hours. The temperature is then lowered with the furnace to obtain a calcium-based desulfurizer.

[0080] Performance testing:

[0081] Desulfurization efficiency test: According to GB / T 19208-2008, 5.00g of sample was loaded into a fixed-bed reactor with a diameter of 20mm. Under constant temperature conditions of 25±1℃, a nitrogen mixture containing 5000ppm hydrogen sulfide was introduced at a flow rate of 200mL / min. The concentration of hydrogen sulfide in the inlet and outlet gases of the reactor was determined by iodometric titration (GB / T 11060.1-2010). The test was stopped when the outlet concentration reached 50% of the inlet concentration. The breakthrough time was recorded and the sulfur capacity (g sulfur / 100g desulfurizer) was calculated. The results are shown in Table 1.

[0082] Pore ​​volume test: The total pore volume was measured using a mercury porosimeter within a pressure range of 0.1-400 MPa. The results are shown in Table 1.

[0083] Mechanical strength test: 30 samples were randomly selected and a universal testing machine was used to test the compressive strength of a single particle at a rate of 0.5 mm / min. The maximum load when the particle broke was recorded and the average compressive strength (N / particle) was calculated. The results are shown in Table 1.

[0084] Regeneration performance test: The desulfurized saturated sample was placed in a tube furnace and regenerated for 2 hours in a nitrogen mixed atmosphere with oxygen concentration of 3% at 450℃. The desulfurization-regeneration cycle was repeated 5 times. After 5 cycles, the sulfur capacity retention rate and mechanical strength were measured. The regeneration gas flow rate was controlled at 100 mL / min and the heating rate was set at 5℃ / min. The results are shown in Table 1.

[0085] Table 1 Performance Test Results

[0086]

[0087] Data Analysis:

[0088] As can be seen from the data in Examples 1-3 of Table 1, the high-porosity calcium-based desulfurizer prepared by this invention exhibits significant advantages in terms of comprehensive performance. Its large pore volume indicates that the material has a high specific surface area and abundant pore structure, which helps to improve the desulfurizer's adsorption capacity and reactivity for hydrogen sulfide. Simultaneously, the material has high compressive strength, indicating excellent mechanical properties, enabling it to withstand certain external forces in practical applications without easily breaking, thus extending its service life. Furthermore, after multiple desulfurization-regeneration cycles, both the sulfur capacity retention rate and mechanical strength retention rate are high, indicating that the desulfurizer exhibits minimal performance degradation during repeated use, demonstrating good stability and regeneration performance.

[0089] As can be seen from the data in Table 1 for Example 2 and Comparative Example 1, the desulfurizer of Example 2 exhibits superior performance in terms of breakthrough time, sulfur capacity, pore volume, and cycle performance compared to Comparative Example 1. This may be related to the introduction of carboxymethyl cellulose loaded with calcium carbonate during the preparation process. This material forms a porous structure with multiple active sites during the later calcination process, thereby enhancing the adsorption capacity and reactivity of the desulfurizer.

[0090] As can be seen from the data in Table 1 for Example 2 and Comparative Example 2, the desulfurizer in Example 2 is superior to that in Comparative Example 2 in terms of desulfurization performance and cycle stability. This may be because during the calcination process, polyethylene glycol-grafted cellulose may form a more stable porous network structure through thermal decomposition and cross-linking reactions, while introducing more active sites on the material surface, thereby significantly improving desulfurization efficiency and pore stability. In contrast, Comparative Example 2 did not use polyethylene glycol-grafted cellulose, which may have resulted in insufficient formation of the pore structure during calcination, thus limiting the performance improvement of the desulfurizer.

[0091] As can be seen from the data in Table 1 for Example 2 and Comparative Example 3, the desulfurizer of Example 2 is superior to that of Comparative Example 2 in terms of decompression resistance and cycle stability. This may be because the zinc coordination structure on the cellulose molecular chain transforms into a ZnO-CaO composite interface at high temperature, forming a "pinning effect" that significantly improves mechanical strength. Furthermore, zinc further promotes the transformation of the carbon layer in the skeleton to graphitization, further enhancing mechanical strength. In contrast, Comparative Example 3 uses unmodified polyethylene glycol-grafted cellulose, which lacks the interfacial strengthening and catalytic effects of zinc ions during calcination, resulting in weaker internal bonding forces within the particles. The skeleton collapses during the regeneration cycle, thus affecting cycle stability.

[0092] As can be seen from the data in Table 1 for Example 2 and Comparative Example 4, the desulfurizer of Example 2 performs better in terms of sulfur capacity, pore volume, and circulation performance. This may be closely related to the adaptability of the polyethylene glycol grafting modification method to the calcination process. In Comparative Example 4, polyethylene glycol blending was used instead of grafting modification. This physical mixing method may lead to the decomposition or migration of polyethylene glycol during calcination, thereby affecting the uniformity and stability of the pore structure. In contrast, Example 2 fixes polyethylene glycol onto the cellulose backbone through chemical grafting, which may form a more stable cross-linked network structure during calcination, thereby effectively regulating pore development.

[0093] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for preparing a high-porosity calcium-based granular desulfurizing agent, characterized in that, Includes the following steps: (1) Add calcium chloride and sodium carboxymethyl cellulose to deionized water, stir at room temperature for 50-70 min, then add sodium carbonate aqueous solution with a concentration of 8-12 wt%, stir at room temperature for 20-40 min, purify, and obtain carboxymethyl cellulose loaded with calcium carbonate. (2) Add carboxymethyl cellulose loaded with calcium carbonate to cyclohexane, stir for 15-25 min, then add polyethylene glycol monomethyl ether and p-toluenesulfonic acid, heat to 80-90℃, reflux and stir for 5-7 h, purify to obtain polyethylene glycol grafted cellulose. (3) Polyethylene glycol grafted cellulose was added to a 4-6 wt% zinc acetate aqueous solution, stirred at room temperature for 60-84 h, and purified to obtain modified cellulose; (4) Add calcium carbonate powder, modified cellulose and sodium carboxymethyl cellulose to deionized water and stir for 10-20 minutes to obtain a slurry; (5) The slurry is granulated by fluidized bed to obtain particles with a particle size D50 of 1.3-1.8 mm; (6) The microparticles were placed in a muffle furnace and calcined to obtain a high-porosity calcium-based desulfurizer; In step (1), the weight ratio of calcium chloride, sodium carboxymethyl cellulose, deionized water and sodium carbonate aqueous solution is 30-50:120-180:1000-1500:400-600. In step (2), the weight ratio of carboxymethyl cellulose, cyclohexane, polyethylene glycol monomethyl ether and p-toluenesulfonic acid loaded with calcium carbonate is 120-180:600-1000:40-60:5-10. In step (2), the weight-average molecular weight of polyethylene glycol monomethyl ether is 3000-5000; In step (3), the weight ratio of polyethylene glycol grafted cellulose and zinc acetate aqueous solution is 150-250:300-800. In step (4), the weight ratio of calcium carbonate powder, modified cellulose, sodium carboxymethyl cellulose and deionized water is 300-500:80-120:8-12:150-250.

2. The preparation method of the high-porosity calcium-based particulate desulfurizer according to claim 1, characterized in that, The degree of substitution of sodium carboxymethyl cellulose in step (1) is 0.8-0.

9.

3. The preparation method of the high-porosity calcium-based particulate desulfurizer according to claim 1, characterized in that, The calcium carbonate powder in step (4) has a mesh size of 200-400.

4. The preparation method of the high-porosity calcium-based particulate desulfurizer according to claim 1, characterized in that, In step (5), the nozzle diameter of the fluidized bed granulation is 0.7-0.9 mm, the fluidizing gas velocity is 0.6-1 m / s, the inlet air temperature is 55-65℃, the outlet air temperature is 35-40℃, the atomization pressure is 0.2-0.3 MPa, and the bottom spray height is 80-120 mm.

5. The preparation method of the high-porosity calcium-based particulate desulfurizer according to claim 1, characterized in that, In step (6), calcination is carried out under a nitrogen atmosphere, with the temperature increased to 430-480℃ at a rate of 4-6℃ / min and held for 0.8-1.2h, then increased to 830-880℃ at a rate of 1-3℃ / min and held for 1.5-2.5h, followed by cooling down in the furnace.

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