Preparation method of environment-friendly and efficient sulfamic acid

Abstract

This invention proposes an environmentally friendly and efficient method for preparing aminosulfonic acid, belonging to the field of chemical technology. It includes: (1) sulfonation reaction; (2) crude product filtration; (3) dissolution and crystallization; and (4) drying and packaging. The reaction process of this invention features mild reaction conditions, short reaction time, and a yield exceeding 97%. The process, using fuming sulfuric acid and urea at a lower temperature, significantly reduces polluting components in the waste gas. It has many advantages, including simple operation, low cost, high yield, and greater environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, specifically to an environmentally friendly and efficient method for preparing aminosulfonic acid. Background Technology

[0002] Sulfamic acid, a derivative of sulfuric acid and commonly known as solid sulfuric acid, is also a post-development product of urea. It is widely used in various industrial equipment manufacturing for metals and ceramics, as well as in civilian cleaning agents, oil well treatment and cleaning agents, electroplating agents, electrochemical polishing agents, etching agents, sulfonating agents for the dye, pharmaceutical, and pigment industries, dyeing agents, high-grade bleaching agents, flame retardants for fibers and paper, softeners, resin crosslinking accelerators, herbicides, anti-bacterial agents, and standard analytical reagents. Derivatives developed from sulfamic acid have significant advantages in pharmaceuticals, pesticides, and electrochemistry. In recent years, food additives and pharmaceutical intermediates produced from sulfamic acid have been widely used in the food and pharmaceutical industries, leading to increasingly widespread demand for sulfamic acid in both domestic and international markets.

[0003] The continuous process for producing aminosulfonic acid using urea as raw material mainly consists of steps such as synthesis, dilution and crude product separation, crude product dissolution, refining, drying, and packaging. The synthesis step is further divided into continuous and batch processes. In the batch process, fuming sulfuric acid is first placed in a synthesis reactor, cooling water is turned on, and urea is added to the reactor in a certain proportion at a specific temperature. After the addition is complete, the temperature is gradually increased to the reaction temperature. After the reaction is complete, the temperature is maintained for a certain period of time before proceeding to the dilution step. The ratio of fuming sulfuric acid to urea in the batch process is significantly lower than that in the continuous process, but it requires more skilled operators. The continuous process, on the other hand, is relatively stable and conducive to automated production. Currently, most large-scale aminosulfonic acid production enterprises adopt the continuous process.

[0004] The continuous process involves adding urea and fuming sulfuric acid to a first synthesis reactor at a specific temperature and ratio for a preliminary reaction, followed by overflow into a second synthesis reactor for further reaction. The fully reacted material is then cooled and enters a dilution process. However, one of the main drawbacks of this method is the large-scale emission of waste gas, which contains significant amounts of acidic substances such as SO2 gas and SO3 powder, causing substantial pollution to the surrounding environment. Summary of the Invention

[0005] The purpose of this invention is to propose an environmentally friendly and efficient method for preparing aminosulfonic acid. The reaction conditions are mild, the reaction time is short, and the yield can reach over 97%. The process of synthesizing aminosulfonic acid using fuming sulfuric acid and urea at a lower temperature significantly reduces polluting components in the waste gas. It has many advantages such as simple operation, low cost, high yield, and greater environmental friendliness.

[0006] The technical solution of this invention is implemented as follows: This invention provides an environmentally friendly and efficient method for preparing aminosulfonic acid, characterized by comprising: (1) Sulfonation reaction: Mix urea with fuming sulfuric acid and control the reaction temperature to not exceed 70°C. Before the addition of urea is finished, use the heat of reaction to raise the temperature to 80-85°C. After the addition of urea is finished, stir and mix evenly, stop stirring, keep the temperature for reaction, and discharge the waste gas generated by the reaction after being purified by a purifying agent. (2) Crude product filtration: The temperature of the reaction system is reduced to 40-50℃, the material is discharged, filtered, and a solid crude product is obtained; (3) Dissolution and crystallization: Mix the crude solid product with the mother liquor, heat to dissolve, flash evaporate the gas and condense it, use the condensate as the mother liquor, cool and crystallize, filter, wash, and obtain aminosulfonic acid crystals; (4) Drying and packaging: The aminosulfonic acid crystals are dried and cooled to obtain the finished product.

[0007] As a further improvement of the present invention, the stirring and mixing time in step (1) is 5-10 min, and the heat preservation reaction time is 1-3 h.

[0008] As a further improvement of the present invention, the heating and melting temperature in step (3) is 60-65°C.

[0009] As a further improvement of the present invention, the purifying agent is activated carbon or a modified purifying agent, and the preparation method of the modified purifying agent is as follows: S1. Preparation of composite metal MOFs: Zinc acetate, cobalt nitrate, and cerium nitrate were dissolved in water, 2-methylimidazole was added, the mixture was stirred at room temperature, centrifuged, washed, and dried to obtain composite metal MOFs; S2. Preparation of porphyrin-Cu-HOF: 5,15-bis(p-methylbenzoate)porphyrin and copper nitrate were dissolved in N,N-dimethylformamide, hydrochloric acid was added, the mixture was stirred and mixed evenly, heated and reacted, centrifuged, washed and dried to obtain porphyrin-Cu-HOF; S3. Preparation of cyclodextrin-Ni-MOF: Mono-6-O-amino-β-cyclodextrin and nickel nitrate were dissolved in N,N-dimethylformamide, acetic acid was added, the mixture was stirred and mixed evenly, heated and reacted, centrifuged, washed and dried to obtain cyclodextrin-Ni-MOF; S4. Mixing: The composite metal MOFs, porphyrin-Cu-HOF, and cyclodextrin-Ni-MOF are mixed, inert gas is introduced, and plasma-assisted ball milling is performed to obtain a mixture; S5. Preparation of purifying agent: Dissolve the ionic liquid in ethanol, add the mixture, stir and mix evenly, remove the solvent under reduced pressure to obtain the purifying agent.

[0010] As a further improvement of the present invention, the mass ratio of zinc acetate, cobalt nitrate, cerium nitrate and 2-methylimidazole in step S1 is 1-1.5:1.2-1.5:0.2-0.4:8-10, and the stirring reaction time at room temperature is 5-7 hours.

[0011] As a further improvement of the present invention, the mass ratio of 5,15-bis(p-methylbenzoate)porphyrin and copper nitrate in step S2 is 2-4:1.4-1.9, and the heating reaction temperature is 75-85℃ for 44-52h.

[0012] As a further improvement of the present invention, the mass ratio of mono-6-O-amino-β-cyclodextrin to nickel nitrate in step S3 is 15-17:3-4, the heating reaction temperature is 100-120℃, and the time is 68-76h.

[0013] As a further improvement of the present invention, the mass ratio of the composite metal MOFs, porphyrin-Cu-HOF, and cyclodextrin-Ni-MOF in step S4 is 10:6-8:2-4, the ball milling time is 10-12 h, and the power supply parameters of the plasma are a discharge voltage of 20-25 kV and a discharge frequency of 10-15 kHz.

[0014] As a further improvement of the present invention, the ionic liquid in step S5 is 1-butyl-3-methylimidazolium tetrafluoroborate or 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, and the mass ratio of the ionic liquid to the mixture is 1-2:4-6.

[0015] This invention involves reacting urea with fuming sulfuric acid, and the reaction process is as follows: (1) Urea reacts with sulfur trioxide in fuming sulfuric acid to produce ureasulfonic acid. (NH₂)₂CO + SO₃ → NH₂CONHSO₃H (2) Urea sulfonic acid reacts further with sulfuric acid to produce aminosulfonic acid. NH2CONHSO3H+H2SO4→2NH2SO3H+CO2 The reaction process is conducted under mild conditions (temperature not exceeding 80℃) and with a short reaction time (within 3 hours), achieving a yield of over 97%. Excessive temperature accelerates the escape of SO3, which is unstable at high temperatures or when exposed to moisture, easily decomposing into SO2. Insufficient reaction time hinders the conversion of ureasulfonic acid to aminosulfonic acid. The process using fuming sulfuric acid and urea at lower temperatures offers numerous advantages, including simple operation, low cost, and high yield.

[0016] However, during the reaction process, a large amount of CO2 waste gas mixed with SO2 and SO3 is easily generated. Direct emission into the atmosphere can easily cause pollution. Too high CO2 emissions can easily cause the greenhouse effect, and SO2 and SO3 emissions can easily cause acid rain. Therefore, it is necessary to purify it.

[0017] The modified purifiers used in this invention first employ MOFs constructed with three different metal ions (Zn, Co, and Ce), possessing more metal defect sites and Lewis acid sites, which enhances the adsorption efficiency for SO3. This invention also prepares porphyrin-Cu-HOF and cyclodextrin-Ni-MOF to construct HOFs and MOFs containing multiple polar groups, introducing abundant hydrogen bonding sites and electrostatic interaction sites to enhance the adsorption of SO2 and SO3. Introducing metal ions into HOFs forms hybrid structures, improving the framework's stability and porosity. Through the formation of unique physical structures, the adsorption capacity for gases is enhanced.

[0018] Metal ions in composite metal MOFs, Cu in porphyrin-Cu-HOF 2+ Ni in cyclodextrin-Ni-MOF 2+ All of these molecules have electron-deficient centers, allowing them to form coordinate bonds with SO2 and SO3, achieving strong chemisorption. The large π bond of the porphyrin ring, the amino group of cyclodextrin, and the imidazole cations of ionic liquids can supplement chemisorption sites through hydrogen bonding, electrostatic interactions, and binding. The cavity size of β-cyclodextrin matches that of SO2 molecules, enabling preferential adsorption and eliminating large molecular interference gases with mismatched sizes.

[0019] High-energy ball milling with plasma assistance achieves high-efficiency preparation of nano-mixtures by bombarding the powder surface with high-pulse discharge plasma coupled with high-pulse plasma. This creates more defect sites on the material surface, while making the three porous materials more uniformly mixed and improving the adsorption reaction rate.

[0020] The present invention has the following beneficial effects: 1. The modified purifying agent used in this invention adsorbs SO2 and SO3 in the waste gas, thereby greatly purifying the polluting components in the waste gas, improving the environmental protection performance, and enabling the discharged waste gas to meet the standard requirements.

[0021] 2. The purifying agent prepared by the present invention can also be reversibly desorbed by heating, depressurization, and inert gas purging. After desorption, the material skeleton and active sites are not easily damaged, so the purifying agent can be reused, thereby reducing production costs. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A flowchart illustrating the preparation process of environmentally friendly and efficient aminosulfonic acid. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Preparation Example 1: Modified Purifying Agent The preparation method is as follows: S1. Preparation of composite metal MOFs: 1g zinc acetate, 1.2g cobalt nitrate and 0.2g cerium nitrate were dissolved in 100mL water, 8g 2-methylimidazole was added, the mixture was stirred at room temperature for 5h, centrifuged, washed and dried to obtain composite metal MOFs; S2. Preparation of porphyrin-Cu-HOF: 0.2 g of 5,15-bis(p-methylbenzoate)porphyrin and 0.14 g of copper nitrate were dissolved in 200 mL of N,N-dimethylformamide, 20 mL of 3 mol / L hydrochloric acid was added, the mixture was stirred for 30 min, heated to 75 °C, and reacted for 44 h. After centrifugation, washing, and drying, porphyrin-Cu-HOF was obtained. S3. Preparation of cyclodextrin-Ni-MOF: 1.5 g of mono-6-O-amino-β-cyclodextrin and 0.3 g of nickel nitrate were dissolved in 200 mL of N,N-dimethylformamide, 40 mL of acetic acid was added, the mixture was stirred for 30 min, heated to 100 °C, and reacted for 68 h. After centrifugation, washing and drying, cyclodextrin-Ni-MOF was obtained. S4. Mixing: Mix 1g of composite metal MOFs, 0.6g of porphyrin-Cu-HOF and 0.2g of cyclodextrin-Ni-MOF, introduce nitrogen gas, and perform plasma-assisted ball milling for 10h. The power supply parameters of the plasma are discharge voltage 20kV and discharge frequency 10kHz to obtain the mixture. S5. Preparation of purifying agent: Dissolve 0.1g of 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate in 100mL of ethanol, add 0.4g of the mixture, stir and mix for 30min, remove the solvent by rotary evaporation under reduced pressure to obtain the purifying agent.

[0026] Preparation Example 2: Modified Purifying Agent The preparation method is as follows: S1. Preparation of composite metal MOFs: 1.5g zinc acetate, 1.5g cobalt nitrate and 0.4g cerium nitrate were dissolved in 100mL of water, 10g 2-methylimidazole was added, the mixture was stirred at room temperature for 7h, centrifuged, washed and dried to obtain composite metal MOFs; S2. Preparation of porphyrin-Cu-HOF: 0.4 g of 5,15-bis(p-methylbenzoate)porphyrin and 0.19 g of copper nitrate were dissolved in 200 mL of N,N-dimethylformamide, 20 mL of 3 mol / L hydrochloric acid was added, the mixture was stirred for 30 min, heated to 85 °C, and reacted for 52 h. After centrifugation, washing, and drying, porphyrin-Cu-HOF was obtained. S3. Preparation of cyclodextrin-Ni-MOF: 1.7 g of mono-6-O-amino-β-cyclodextrin and 0.4 g of nickel nitrate were dissolved in 200 mL of N,N-dimethylformamide, 40 mL of acetic acid was added, the mixture was stirred for 30 min, heated to 120 °C, and reacted for 76 h. After centrifugation, washing and drying, cyclodextrin-Ni-MOF was obtained. S4. Mixing: Mix 1g of composite metal MOFs, 0.8g of porphyrin-Cu-HOF and 0.4g of cyclodextrin-Ni-MOF, introduce nitrogen gas, and perform plasma-assisted ball milling for 12h. The power supply parameters of the plasma are discharge voltage 25kV and discharge frequency 15kHz to obtain the mixture. S5. Preparation of purifying agent: Dissolve 0.2g of 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate in 100mL of ethanol, add 0.6g of the mixture, stir and mix for 30min, remove the solvent by rotary evaporation under reduced pressure to obtain the purifying agent.

[0027] Preparation Example 3: Modified Purifying Agent The preparation method is as follows: S1. Preparation of composite metal MOFs: 1.2g zinc acetate, 1.3g cobalt nitrate and 0.3g cerium nitrate were dissolved in 100mL water, 9g 2-methylimidazole was added, the mixture was stirred at room temperature for 6h, centrifuged, washed and dried to obtain composite metal MOFs; S2. Preparation of porphyrin-Cu-HOF: 0.3 g of 5,15-bis(p-methylbenzoate)porphyrin and 0.17 g of copper nitrate were dissolved in 200 mL of N,N-dimethylformamide, 20 mL of 3 mol / L hydrochloric acid was added, the mixture was stirred for 30 min, heated to 80 °C, and reacted for 48 h. After centrifugation, washing, and drying, porphyrin-Cu-HOF was obtained. S3. Preparation of cyclodextrin-Ni-MOF: 1.6 g of mono-6-O-amino-β-cyclodextrin and 0.35 g of nickel nitrate were dissolved in 200 mL of N,N-dimethylformamide, 40 mL of acetic acid was added, the mixture was stirred for 30 min, heated to 110 °C, and reacted for 72 h. After centrifugation, washing and drying, cyclodextrin-Ni-MOF was obtained. S4. Mixing: Mix 1g of composite metal MOFs, 0.7g of porphyrin-Cu-HOF and 0.3g of cyclodextrin-Ni-MOF, introduce nitrogen gas, and perform plasma-assisted ball milling for 11h. The power supply parameters of the plasma are discharge voltage 22kV and discharge frequency 12kHz to obtain the mixture. S5. Preparation of purifying agent: Dissolve 0.15g of 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate in 100mL of ethanol, add 0.5g of the mixture, stir and mix for 30min, remove the solvent by rotary evaporation under reduced pressure to obtain the purifying agent.

[0028] Comparative Preparation Example 1 The difference from preparation example 3 is that no composite metal MOFs were added in step S4.

[0029] Specifically as follows: S1. Preparation of porphyrin-Cu-HOF: 0.3 g of 5,15-bis(p-methylbenzoate)porphyrin and 0.17 g of copper nitrate were dissolved in 200 mL of N,N-dimethylformamide, 20 mL of 3 mol / L hydrochloric acid was added, the mixture was stirred for 30 min, heated to 80 °C, and reacted for 48 h. After centrifugation, washing, and drying, porphyrin-Cu-HOF was obtained. S2. Preparation of cyclodextrin-Ni-MOF: 1.6 g of mono-6-O-amino-β-cyclodextrin and 0.35 g of nickel nitrate were dissolved in 200 mL of N,N-dimethylformamide, 40 mL of acetic acid was added, the mixture was stirred for 30 min, heated to 110 °C, and reacted for 72 h. After centrifugation, washing and drying, cyclodextrin-Ni-MOF was obtained. S3. Mixing: Mix 0.7g porphyrin-Cu-HOF and 0.3g cyclodextrin-Ni-MOF, introduce nitrogen gas, and perform plasma-assisted ball milling for 11h. The power supply parameters of the plasma are discharge voltage 22kV and discharge frequency 12kHz to obtain the mixture. S4. Preparation of purifying agent: Dissolve 0.15g of 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate in 100mL of ethanol, add 0.5g of the mixture, stir and mix for 30min, remove the solvent by rotary evaporation under reduced pressure to obtain the purifying agent.

[0030] Comparative Preparation Example 2 The difference from Preparation Example 3 is that porphyrin-Cu-HOF was not added in step S4.

[0031] Specifically as follows: S1. Preparation of composite metal MOFs: 1.2g zinc acetate, 1.3g cobalt nitrate and 0.3g cerium nitrate were dissolved in 100mL water, 9g 2-methylimidazole was added, the mixture was stirred at room temperature for 6h, centrifuged, washed and dried to obtain composite metal MOFs; S2. Preparation of cyclodextrin-Ni-MOF: 1.6 g of mono-6-O-amino-β-cyclodextrin and 0.35 g of nickel nitrate were dissolved in 200 mL of N,N-dimethylformamide, 40 mL of acetic acid was added, the mixture was stirred for 30 min, heated to 110 °C, and reacted for 72 h. After centrifugation, washing and drying, cyclodextrin-Ni-MOF was obtained. S3. Mixing: Mix 1g of composite metal MOFs and 0.3g of cyclodextrin-Ni-MOF, introduce nitrogen gas, and perform plasma-assisted ball milling for 11h. The power supply parameters of the plasma are discharge voltage 22kV and discharge frequency 12kHz to obtain the mixture. S4. Preparation of purifying agent: Dissolve 0.15g of 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate in 100mL of ethanol, add 0.5g of the mixture, stir and mix for 30min, remove the solvent by rotary evaporation under reduced pressure to obtain the purifying agent.

[0032] Comparative preparation example 3 The difference from Preparation Example 3 is that cyclodextrin-Ni-MOF was not added in step S4.

[0033] Specifically as follows: S1. Preparation of composite metal MOFs: 1.2g zinc acetate, 1.3g cobalt nitrate and 0.3g cerium nitrate were dissolved in 100mL water, 9g 2-methylimidazole was added, the mixture was stirred at room temperature for 6h, centrifuged, washed and dried to obtain composite metal MOFs; S2. Preparation of porphyrin-Cu-HOF: 0.3 g of 5,15-bis(p-methylbenzoate)porphyrin and 0.17 g of copper nitrate were dissolved in 200 mL of N,N-dimethylformamide, 20 mL of 3 mol / L hydrochloric acid was added, the mixture was stirred for 30 min, heated to 80 °C, and reacted for 48 h. After centrifugation, washing, and drying, porphyrin-Cu-HOF was obtained. S3. Mixing: 1g of composite metal MOFs and 0.7g of porphyrin-Cu-HOF were mixed, nitrogen gas was introduced, and plasma-assisted ball milling was performed for 11h. The power supply parameters of the plasma were discharge voltage 22kV and discharge frequency 12kHz to obtain the mixture. S4. Preparation of purifying agent: Dissolve 0.15g of 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate in 100mL of ethanol, add 0.5g of the mixture, stir and mix for 30min, remove the solvent by rotary evaporation under reduced pressure to obtain the purifying agent.

[0034] Comparative preparation example 4 The difference from preparation example 3 is that plasma treatment was not used in step S4.

[0035] Specifically as follows: S1. Preparation of composite metal MOFs: 1.2g zinc acetate, 1.3g cobalt nitrate and 0.3g cerium nitrate were dissolved in 100mL water, 9g 2-methylimidazole was added, the mixture was stirred at room temperature for 6h, centrifuged, washed and dried to obtain composite metal MOFs; S2. Preparation of porphyrin-Cu-HOF: 0.3 g of 5,15-bis(p-methylbenzoate)porphyrin and 0.17 g of copper nitrate were dissolved in 200 mL of N,N-dimethylformamide, 20 mL of 3 mol / L hydrochloric acid was added, the mixture was stirred for 30 min, heated to 80 °C, and reacted for 48 h. After centrifugation, washing, and drying, porphyrin-Cu-HOF was obtained. S3. Preparation of cyclodextrin-Ni-MOF: 1.6 g of mono-6-O-amino-β-cyclodextrin and 0.35 g of nickel nitrate were dissolved in 200 mL of N,N-dimethylformamide, 40 mL of acetic acid was added, the mixture was stirred for 30 min, heated to 110 °C, and reacted for 72 h. After centrifugation, washing and drying, cyclodextrin-Ni-MOF was obtained. S4. Mixing: Mix 1g of composite metal MOFs, 0.7g of porphyrin-Cu-HOF and 0.3g of cyclodextrin-Ni-MOF, and ball mill for 11h to obtain a mixture; S5. Preparation of purifying agent: Dissolve 0.15g of 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate in 100mL of ethanol, add 0.5g of the mixture, stir and mix for 30min, remove the solvent by rotary evaporation under reduced pressure to obtain the purifying agent.

[0036] Comparative preparation example 5 The difference from preparation example 3 is that step S5 was not performed.

[0037] Specifically as follows: S1. Preparation of composite metal MOFs: 1.2g zinc acetate, 1.3g cobalt nitrate and 0.3g cerium nitrate were dissolved in 100mL water, 9g 2-methylimidazole was added, the mixture was stirred at room temperature for 6h, centrifuged, washed and dried to obtain composite metal MOFs; S2. Preparation of porphyrin-Cu-HOF: 0.3 g of 5,15-bis(p-methylbenzoate)porphyrin and 0.17 g of copper nitrate were dissolved in 200 mL of N,N-dimethylformamide, 20 mL of 3 mol / L hydrochloric acid was added, the mixture was stirred for 30 min, heated to 80 °C, and reacted for 48 h. After centrifugation, washing, and drying, porphyrin-Cu-HOF was obtained. S3. Preparation of cyclodextrin-Ni-MOF: 1.6 g of mono-6-O-amino-β-cyclodextrin and 0.35 g of nickel nitrate were dissolved in 200 mL of N,N-dimethylformamide, 40 mL of acetic acid was added, the mixture was stirred for 30 min, heated to 110 °C, and reacted for 72 h. After centrifugation, washing and drying, cyclodextrin-Ni-MOF was obtained. S4. Mixing: Mix 1g of composite metal MOFs, 0.7g of porphyrin-Cu-HOF and 0.3g of cyclodextrin-Ni-MOF, introduce nitrogen gas, and perform plasma-assisted ball milling for 11h. The power supply parameters of the plasma are discharge voltage 22kV and discharge frequency 12kHz. The resulting mixture is the purifying agent.

[0038] Preparation Example 1 The specific surface area of ​​the purifying agents prepared in Preparation Examples 1-3 and Comparative Preparation Examples 1-5 was determined using a 3-FLEX 3500 multi-station high-throughput gas adsorption analyzer. The results are shown in Table 1.

[0039] Table 1

[0040] As can be seen from the table above, the purifying agents prepared in Examples 1-3 of the present invention have a large specific surface area.

[0041] Example 1 This embodiment provides an environmentally friendly and efficient method for preparing aminosulfonic acid, including the following steps: (1) Sulfonation reaction like Figure 1The urea in ton bags is manually unpacked and stored in a urea silo via a bucket elevator. A high-level metering tank for fuming sulfuric acid is installed, equipped with an automatic metering device for fuming sulfuric acid. Fuming sulfuric acid from the metering tank is added to the sulfonation reactor in one go, and stirring is started. Urea from the urea silo is added to the designated urea conveying and agitating metering hopper on the sulfonation reactor via a tubular chain conveyor. The stirring speed is controlled by a frequency converter to control the urea addition rate. When the material temperature in the sulfonation reactor reaches approximately 65°C, the cooling water in the sulfonation reactor jacket is opened to the maximum, and the urea addition rate is adjusted to maintain the material temperature in the sulfonation reactor below 70°C. The amount of urea added is measured by cumulative weight loss until all the material is added according to the material ratio. Near the end of the urea addition, the temperature of the material in the reactor is raised to 85°C using the heat of reaction. After the urea is added, stirring continues for 5 minutes, the cooling water is turned off, stirring is stopped, and the temperature is maintained for two hours. The waste gas generated by the reaction is adsorbed and purified for 20 minutes using the purifying agent prepared in Example 1, then tested, and discharged only after meeting the standards. The ratio of urea to fuming sulfuric acid is 1:6.2.

[0042] (2) Crude product filtration After the sulfonation reactor has been kept at a constant temperature for two hours, the stirring and cooling water are turned on to cool the material inside the reactor to below 45°C. Washing water is then added for dilution, with the cooling water flow set to maximum. The valve controls the rate of addition of washing water to maintain the material temperature inside the reactor below 70°C. Once a certain amount of washing water has been added, the material temperature begins to drop, at which point the addition of washing water is stopped. Under stirring and circulating water cooling, the material temperature is lowered to below 45°C. The pneumatic PTFE-lined ball valve at the bottom of the reactor is opened, and the material flows along the bottom discharge pipe into the crude slurry underground tank. It is buffered in the tank under stirring, forming the crude slurry. After discharge, the pneumatic PTFE-lined ball valve at the bottom of the reactor is closed, the circulating cooling water is stopped, and the sulfonation reactor enters the next operating cycle.

[0043] The coarse slurry from the underground tank is pumped by a vertical fiberglass pump to a high-level buffer tank with agitation before the vacuum belt filter. The flow rate is controlled by an electrically operated PTFE-lined ball valve at the bottom of the tank, allowing the slurry to flow steadily into the feed distributor at the vacuum belt filter inlet for solid-liquid separation. The balance between the pump input to the high-level buffer tank and the amount of slurry flowing into the belt filter from the high-level buffer tank is maintained. The coarse slurry flows into the filter, and the liquid discharged from the first drain tank is dilute acid, which flows into a two-stage dilute acid settling tank. The cleaner dilute acid is pumped into a dilute acid storage tank. After the dilute acid filtration section, a mother liquor pipe is installed to spray mother liquor, which washes the filter cake, displacing the sulfuric acid. The mother liquor acid concentration increases to approximately 30%, becoming wash water, which is discharged from the second and third drain tanks and flows into two underground wash water tanks. The cleaner wash water is pumped into the sulfonation section for dilution. The precipitated material in the settling tank is periodically cleaned and returned to the coarse slurry underground tank for reuse.

[0044] (3) Dissolution and crystallization The crude solid obtained by vacuum belt filter filtration and washing falls into the dissolving slurry tank, where mother liquor is added simultaneously. Under stirring, a uniform crude solid slurry is formed. The density of the crude solid slurry is controlled so that the crude solid can be completely dissolved at a temperature not exceeding 65°C. The crude solid slurry is pumped into an enamel-lined dissolving kettle, and steam is introduced into the outer jacket of the kettle to completely dissolve the crude solid slurry into a transparent liquid in the shortest possible time at a material temperature not exceeding 65°C. If the temperature at which the crude solid completely dissolves is too low or too high, it can be adjusted by adding solid crude solid or mother liquor and water. The steam valve is closed, and the electric PTFE-lined ball valve at the bottom of the dissolving kettle is slowly opened. The completely dissolved crude solution flows by gravity into the dissolving buffer tank through the guide pipe at the bottom of the dissolving kettle. It is then quantitatively pumped into the flash tank, and the discharge from the flash tank is pumped into the crystallization tank by a transfer pump. The crystallization tank has a circulating water jacket, where the dissolving solution is cooled and crystallized. The crystallized aminosulfonic acid crystals flow into the thickener along with the mother liquor. The gas extracted from the flash tank is condensed by the condenser, and the condensate enters the mother liquor tank for dissolving the crude product and washing the crude product after filtration.

[0045] (4) Drying and packaging The finished product drying adopts vibrating fluidized bed technology, which uses superheated steam generated by the waste heat of the sulfuric acid plant production system as a heat source. The air is heated to about 150°C through a finned radiator and then blower is sent into the vibrating fluidized bed.

[0046] The centrifuge discharges the material into the pre-drying hopper, where it is quantitatively conveyed into the vibrating fluidized bed by a variable frequency auger. The aminosulfonic acid crystals contain approximately 5% free water and disperse within the fluidized bed due to airflow and vibration, exhibiting a jumping and boiling state. In the fluidized bed drying section, surface moisture is carried away by hot air. In the fluidized bed cooling section, the crystal temperature is reduced to below 40°C. After passing through the fluidized bed, the aminosulfonic acid crystals directly enter a vibrating screen, where larger particles and binders are separated. The finished aminosulfonic acid is then conveyed to the finished product silo by an elevator. Testing shows an aminosulfonic acid yield >97%, and it is quantitatively packaged and stored according to the national chemical industry standard packaging requirements for aminosulfonic acid.

[0047] During the drying and cooling process of aminosulfonic acid crystals, the fine crystals float in the air due to air blowing in and exhaust by the fan, generating waste gas. After being treated by a cyclone dust collector and a bag filter, the exhaust gas is discharged into the atmosphere. The collected fine particles are recycled and packaged in the finished product warehouse for storage.

[0048] Example 2 The difference from Example 1 is that the purifying agent was prepared in Preparation Example 2.

[0049] Example 3 The difference from Example 1 is that the purifying agent was prepared by Preparation Example 3.

[0050] Comparative Example 1 The difference from Example 1 is that the purifying agent was prepared by Comparative Preparation Example 1.

[0051] Comparative Example 2 The difference from Example 1 is that the purifying agent was prepared from Comparative Preparation Example 2.

[0052] Comparative Example 3 The difference from Example 1 is that the purifying agent was prepared from Comparative Preparation Example 3.

[0053] Comparative Example 4 The difference from Example 1 is that the purifying agent was prepared by Comparative Preparation Example 4.

[0054] Comparative Example 5 The difference from Example 1 is that the purifying agent was prepared from Comparative Preparation Example 5.

[0055] Test Example 2 The exhaust gases from Examples 1-3 and Comparative Examples 1-5 after treatment with the purifying agent were tested, and the results are shown in Table 2.

[0056] Table 2

[0057] As can be seen from the table above, the SO2 and SO3 content in the exhaust gas after purification treatment in Examples 1-3 of the present invention is significantly reduced.

[0058] Test Example 3 After the purifying agent in Example 3 was heated and desorbed by nitrogen purging, the experiment in Example 3 was repeated 5 times. The exhaust gas was tested after each purification, and the results are shown in Table 3.

[0059] Table 3

[0060] As can be seen from the table above, the SO2 and SO3 content in the exhaust gas after purification treatment in Example 3 of the present invention is still low, indicating that the purifier still maintains a good purification effect after repeated use.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing environmentally friendly and efficient aminosulfonic acid, characterized in that, include: (1) Sulfonation reaction: Mix urea with fuming sulfuric acid and control the reaction temperature to not exceed 70°C. Before the addition of urea is finished, use the heat of reaction to raise the temperature to 80-85°C. After the addition of urea is finished, stir and mix evenly, stop stirring, keep the temperature for reaction, and discharge the waste gas generated by the reaction after being purified by a purifying agent. (2) Crude product filtration: The temperature of the reaction system is reduced to 40-50℃, the material is discharged, filtered, and a solid crude product is obtained; (3) Dissolution and crystallization: Mix the crude solid product with the mother liquor, heat to dissolve, flash evaporate the gas and condense it, use the condensate as the mother liquor, cool and crystallize, filter, wash, and obtain aminosulfonic acid crystals; (4) Drying and packaging: The aminosulfonic acid crystals are dried and cooled to obtain the finished product.

2. The preparation method according to claim 1, characterized in that, The stirring and mixing time in step (1) is 5-10 min, and the heat preservation reaction time is 1-3 h.

3. The preparation method according to claim 1, characterized in that, The heating and melting temperature in step (3) is 60-65℃.

4. The preparation method according to claim 1, characterized in that, The purifying agent is activated carbon or a modified purifying agent, and the preparation method of the modified purifying agent is as follows: S1. Preparation of composite metal MOFs: Zinc acetate, cobalt nitrate, and cerium nitrate were dissolved in water, 2-methylimidazole was added, the mixture was stirred at room temperature, centrifuged, washed, and dried to obtain composite metal MOFs; S2. Preparation of porphyrin-Cu-HOF: 5,15-bis(p-methylbenzoate)porphyrin and copper nitrate were dissolved in N,N-dimethylformamide, hydrochloric acid was added, the mixture was stirred and mixed evenly, heated and reacted, centrifuged, washed and dried to obtain porphyrin-Cu-HOF; S3. Preparation of cyclodextrin-Ni-MOF: Mono-6-O-amino-β-cyclodextrin and nickel nitrate were dissolved in N,N-dimethylformamide, acetic acid was added, the mixture was stirred and mixed evenly, heated and reacted, centrifuged, washed and dried to obtain cyclodextrin-Ni-MOF; S4. Mixing: The composite metal MOFs, porphyrin-Cu-HOF, and cyclodextrin-Ni-MOF are mixed, inert gas is introduced, and plasma-assisted ball milling is performed to obtain a mixture; S5. Preparation of purifying agent: Dissolve the ionic liquid in ethanol, add the mixture, stir and mix evenly, remove the solvent under reduced pressure to obtain the purifying agent.

5. The preparation method according to claim 4, characterized in that, In step S1, the mass ratio of zinc acetate, cobalt nitrate, cerium nitrate, and 2-methylimidazole is 1-1.5:1.2-1.5:0.2-0.4:8-10, and the stirring reaction at room temperature lasts for 5-7 hours.

6. The preparation method according to claim 4, characterized in that, The mass ratio of 5,15-bis(p-methylbenzoate)porphyrin to copper nitrate in step S2 is 2-4: 1.4-1.9, the heating reaction temperature is 75-85℃, and the time is 44-52h.

7. The preparation method according to claim 4, characterized in that, In step S3, the mass ratio of mono-6-O-amino-β-cyclodextrin to nickel nitrate is 15-17:3-4, the heating reaction temperature is 100-120℃, and the time is 68-76h.

8. The preparation method according to claim 4, characterized in that, In step S4, the mass ratio of the composite metal MOFs, porphyrin-Cu-HOF, and cyclodextrin-Ni-MOF is 10:6-8:2-4, the ball milling time is 10-12 hours, and the power supply parameters of the plasma are a discharge voltage of 20-25 kV and a discharge frequency of 10-15 kHz.

9. The preparation method according to claim 4, characterized in that, The ionic liquid in step S5 is 1-butyl-3-methylimidazolium tetrafluoroborate or 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, and the mass ratio of the ionic liquid to the mixture is 1-2:4-6.

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