Green dimethyl sulfate production process based on sulfur trioxide purification
High-purity sulfur trioxide was prepared by sulfonating molecular sieves. Combined with step-by-step esterification reaction and low-temperature distillation, the safety and efficiency issues in the production of dimethyl sulfate were solved, and green production was achieved.
Patent Information
- Application Number
- CN202511064442.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-31
- Publication Date
- 2025-11-07
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of preparation of organic chemical raw material dimethyl sulfate, and particularly relates to a dimethyl sulfate green production process based on sulfur trioxide purification. BACKGROUND
[0002] Dimethyl sulfate is a colorless or slightly yellowish, slightly onion-scented, flammable liquid chemical product, slightly soluble in water, soluble in ethanol, diethyl ether, acetone and the like. Dimethyl sulfate is a good methylating agent and is widely used in the fields of chemical industry, medicine, pesticide and perfume, and is a production raw material of dimethyl sulfoxide, caffeine, vanillin, aminopyrine, trimethoprim and acetamiprid. There are many synthesis methods of dimethyl sulfate, such as sodium salt method, direct reaction of anhydrous sulfuric acid and methanol, dimethyl ether and sulfur trioxide synthesis method, chlorosulfonic acid synthesis method, hydrogen methyl sulfate method and the like. It is a colorless or slightly yellowish, slightly onion-scented, flammable liquid chemical product, slightly soluble in water, soluble in ethanol, diethyl ether, acetone and the like. Dimethyl sulfate is a good methylating agent, and there are many synthesis methods. At the same time, dimethyl sulfate is also a potential carcinogen, which enters the human body through inhalation and skin contact, is harmful to the respiratory system, skin and digestive system and has strong corrosive property. It reacts violently with water and many common solvents to produce toxic gases. In order to ensure the safe and stable production of dimethyl sulfate, automatic control needs to be applied to chemical production, so as to reduce the risk, ensure the safety of production and improve the production efficiency.
[0003] In summary, the high toxicity and high environmental risk of dimethyl sulfate make its green production become the core challenge for the sustainable development of the industry. SUMMARY
[0004] The purpose of the present application is to provide a dimethyl sulfate green production process based on sulfur trioxide purification, which prepares high-purity purified sulfur trioxide by using sulfonated molecular sieves, removes impurities, performs a step-by-step esterification reaction in two stages, does not need to use a catalyst, uses sulfonated molecular sieves for dynamic dehydration, and finally completes the dimethyl sulfate green production process through low-temperature rectification.
[0005] The purpose of the present application can be achieved by the following technical solutions: A dimethyl sulfate green production process based on sulfur trioxide purification, comprising the following steps: The sulfonated molecular sieve powder is loaded into a 3-5A grade molecular sieve tower, and industrial grade sulfur trioxide with a purity of 98-99% is introduced into the molecular sieve tower to remove heavy metal impurities by crystallization separation at-15 to-10°C to obtain purified sulfur trioxide; methanol and purified sulfur trioxide are added to a reaction kettle, stirred at 40-50°C and 500-600 r / min for 30-40 min, then methanol is added again, heated to 60-70°C, and the reaction is continued for 2-3 h, then the sulfonated molecular sieve powder is added for in-situ dehydration, and the stirring is continued for 1-2 h to reduce the moisture content to 0.03-0.05%, and dimethyl sulfate is obtained by vacuum rectification at a pressure of 50-80 KPa, thus completing a green production process of dimethyl sulfate based on sulfur trioxide purification.
[0006] Further, the amount ratio of methanol, sulfonated molecular sieve powder and purified sulfur trioxide is 90-110 mL:38-42 g:2-3 g.
[0007] Further, the specific preparation steps of the sulfonated molecular sieve powder are as follows: Chitosan, 3-mercaptopropyltrimethoxysilane and ethanol are added to a reaction kettle, stirred at 60-70°C and 500-600 r / min for 1-2 h, filtered, the filter cake is washed with deionized water for 2-4 times, vacuum dried at 60-70°C for 1-2 h to obtain a mercapto-coated layer; the mercapto-coated layer, molecular sieve precursor powder and hydrogen peroxide solution with a mass fraction of 20-30% are added to a reaction kettle, stirred at 20-25°C and 500-600 r / min for 1-2 h, then 0.5M sodium hydroxide solution is added to pH 9, filtered, the filter cake is washed with deionized water and ethanol for 2-4 times, vacuum dried at 60-70°C for 1-2 h, and the product is transferred to a muffle furnace, calcined at 500-600°C for 2-3 h under nitrogen protection to obtain the sulfonated molecular sieve powder.
[0008] Further, the amount ratio of chitosan, 3-mercaptopropyltrimethoxysilane and ethanol is 60-70 g:120-200 mL:300-400 mL.
[0009] Further, the amount ratio of the mercapto-coated layer, molecular sieve precursor powder and hydrogen peroxide solution is 40-50 g:20-30 g:300-400 mL.
[0010] Further, the specific preparation steps of the molecular sieve precursor powder are as follows: 5-hydroxyisophthalic acid, calcium-based diatomite and deionized water are added into a reaction kettle, sodium dodecyl sulfate is dissolved in 100-120 mL of 70-80 wt% ethanol solution and then added into the reaction kettle, stirring is carried out at 120-130 DEG C and 400-500 r / min for 1-2 h, magnesium chloride is added into the reaction kettle, and the reaction is continuously stirred for 4-5 h, then filtration is carried out, the filter cake is washed with deionized water and anhydrous ethanol for 2-4 times respectively, and vacuum drying is carried out at 60-70 DEG C for 1-2 h, so as to obtain the molecular sieve precursor powder.
[0011] Further, the amount ratio of 5-hydroxyisophthalic acid, calcium-based diatomite, deionized water, sodium dodecyl sulfate, ethanol solution and magnesium chloride is 50-60 g:40-50 g:1-2 L:5-7 g:40-50 g.
[0012] Further, the specific preparation steps of the calcium-based diatomite are as follows: A sodium bicarbonate solution with a mass fraction of 10-15% and diatomite are added into a reaction kettle, vacuum impregnation is carried out at 20-25 DEG C and 500-600 r / min for 2-3 h, then a calcium chloride solution with a mass fraction of 40-50% is added, and the reaction is continuously carried out for 1-2 h, then filtration is carried out, the filter cake is washed with deionized water and anhydrous ethanol for 2-4 times respectively, and vacuum drying is carried out at 60-70 DEG C for 1-2 h, so as to obtain the calcium-based diatomite.
[0013] Further, the amount ratio of the sodium bicarbonate solution, diatomite and calcium chloride solution is 100-120 mL:50-60 g:120-140 mL.
[0014] The beneficial effects of the present application are as follows: 1. The present application provides a green production process of dimethyl sulfate based on sulfur trioxide purification, high-purity purified sulfur trioxide is prepared by using sulfonated molecular sieve, impurities are removed, and then two-stage stepwise esterification reaction is carried out, without the use of catalyst, and dynamic dehydration is carried out by using sulfonated molecular sieve, and finally low-temperature rectification is carried out to complete the green production process of dimethyl sulfate.
[0015] 2. The sulfonated molecular sieve powder of the present application is obtained by the reaction of the hydroxyl groups of chitosan with the silane groups generated by the hydrolysis of 3-mercaptopropyl trimethoxysilane, a sulfonated chitosan coating layer is obtained, the molecular sieve precursor is coated, and then carbonization is carried out to obtain sulfonated molecular sieve with multi-level pores, because of the existence of multi-level pores and the dissociation of sulfonic acid groups in the solution, permanent negative charged surface sites are formed, which can adsorb and remove positively charged heavy metal ions, so as to obtain high-purity purified sulfur trioxide, and ensure the green production of dimethyl sulfate. DETAILED DESCRIPTION
[0016] The technical solutions in the embodiments of the present application will be clearly and completely described below with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.
[0017] Embodiment 1: A green production process of dimethyl sulfate based on sulfur trioxide purification, comprising the following steps: S1: 100 mL of 10% sodium bicarbonate solution and 50 g of diatomite are added into a reaction kettle, vacuum impregnation is carried out at 20 ℃ and 500 r / min for 2 h, then 120 mL of 40% calcium chloride solution is added, and reaction is continued for 1 h, filtration is carried out, the filter cake is washed with deionized water and anhydrous ethanol for 2 times respectively, and vacuum drying is carried out at 60 ℃ for 1 h to obtain calcium-based diatomite.
[0018] S2: 50 g of 5-hydroxyisophthalic acid, 40 g of calcium-based diatomite and 1 L of deionized water are added into a reaction kettle, 5 g of sodium hexadecyl sulfate is dissolved in 100 mL of 70 wt% ethanol solution and then added into the reaction kettle, stirring is carried out at 120 ℃ and 400 r / min for 1 h, 40 g of magnesium chloride is added into the reaction kettle, and stirring reaction is continued for 4 h, filtration is carried out, the filter cake is washed with deionized water and anhydrous ethanol for 2 times respectively, and vacuum drying is carried out at 60 ℃ for 1 h to obtain a molecular sieve precursor powder.
[0019] S3: 60 g of chitosan, 120 mL of 3-mercaptopropyltrimethoxysilane and 300 mL of ethanol are added into a reaction kettle, stirring is carried out at 60 ℃ and 500 r / min for 1 h, filtration is carried out, the filter cake is washed with deionized water for 2 times, and vacuum drying is carried out at 60 ℃ for 1 h to obtain a mercapto-coated layer; 40 g of the mercapto-coated layer, 20 g of the molecular sieve precursor powder and 300 mL of 20% hydrogen peroxide solution are added into a reaction kettle, stirring reaction is carried out at 20 ℃ and 500 r / min for 1 h, then 0.5 M sodium hydroxide solution is added until the pH value is 9, filtration is carried out, the filter cake is washed with deionized water and ethanol for 2 times, vacuum drying is carried out at 60 ℃ for 1 h, the product is transferred into a muffle furnace, calcination is carried out at 500 ℃ for 2 h under nitrogen protection to obtain a sulfonated molecular sieve powder.
[0020] S4: The sulfonated molecular sieve powder is loaded into a 3A molecular sieve tower, and industrial-grade sulfur trioxide with a purity of 98% is introduced into the molecular sieve tower to remove heavy metal impurities by crystallization separation at -15°C to obtain purified sulfur trioxide; 50 mL of methanol and 38 g of purified sulfur trioxide are added to the reaction kettle, stirred at 40°C and 500 r / min for 30 min, then 40 mL of methanol is added, heated to 60°C, and continues to react for 2 h, then 2 g of sulfonated molecular sieve powder is added for in-situ dehydration, continues to stir for 1 h, the water content is reduced to 0.03%, and the pressure is reduced to 50 KPa to obtain dimethyl sulfate by vacuum rectification, completing a green production process of dimethyl sulfate based on sulfur trioxide purification.
[0021] Example 2: A green production process of dimethyl sulfate based on sulfur trioxide purification, comprising the following steps: S1: 110 mL of a sodium bicarbonate solution with a mass fraction of 12.5% and 55 g of diatomite are added to the reaction kettle, vacuum impregnated at 22.5°C and 550 r / min for 2.5 h, then 130 mL of a calcium chloride solution with a mass fraction of 45% is added, and continues to react for 1.5 h, then filtered, the filter cake is washed with deionized water and anhydrous ethanol for 3 times respectively, and vacuum dried at 65°C for 1.5 h to obtain calcium-based diatomite.
[0022] S2: 55 g of 5-hydroxyisophthalic acid, 45 g of calcium-based diatomite, and 1.5 L of deionized water are added to the reaction kettle, 6 g of sodium hexadecyl sulfate is dissolved in 110 mL of 75 wt% ethanol solution and then added to the reaction kettle, stirred at 125°C and 450 r / min for 1.5 h, 45 g of magnesium chloride is added to the reaction kettle, and continues to stir for 4.5 h, then filtered, the filter cake is washed with deionized water and anhydrous ethanol for 3 times respectively, and vacuum dried at 65°C for 1.5 h to obtain molecular sieve precursor powder.
[0023] S3: 65 g of chitosan, 160 mL of 3-mercaptopropyltrimethoxysilane, and 350 mL of ethanol are added to the reaction kettle, stirred at 65°C and 550 r / min for 1.5 h, filtered, the filter cake is washed with deionized water for 3 times, and vacuum dried at 65°C for 1.5 h to obtain a mercapto-coated layer; 45 g of the mercapto-coated layer, 25 g of the molecular sieve precursor powder, and 350 mL of a hydrogen peroxide solution with a mass fraction of 25% are added to the reaction kettle, stirred at 22.5°C and 550 r / min for 1.5 h, then a 0.5 M sodium hydroxide solution is added to adjust the pH value to 9, filtered, the filter cake is washed with deionized water and ethanol for 3 times, and vacuum dried at 65°C for 1.5 h, then the product is transferred to a muffle furnace, calcined at 550°C for 2.5 h under nitrogen protection to obtain sulfonated molecular sieve powder.
[0024] S4: The sulfonated molecular sieve powder is loaded into a 4A molecular sieve tower, and industrial-grade sulfur trioxide with a purity of 98.5% is introduced into the molecular sieve tower to remove heavy metal impurities by crystallization separation at -12.5°C to obtain purified sulfur trioxide; 55 mL of methanol and 40 g of purified sulfur trioxide are added to the reaction kettle, stirred at 45°C and 550 r / min for 35 min, then 45 mL of methanol is added, heated to 65°C, and reacted for another 2.5 h, then 2.5 g of sulfonated molecular sieve powder is added for in-situ dehydration, and stirred for another 1.5 h to reduce the water content to 0.04%, and then distilled under reduced pressure at a pressure of 65 KPa to obtain dimethyl sulfate, thus completing a green production process of dimethyl sulfate based on sulfur trioxide purification.
[0025] Example 3: A green production process of dimethyl sulfate based on sulfur trioxide purification, comprising the following steps: S1: 120 mL of a 15% mass fraction sodium bicarbonate solution and 60 g of diatomite are added to the reaction kettle, vacuum impregnated at 25°C and 600 r / min for 3 h, then 140 mL of a 50% mass fraction calcium chloride solution is added, and the reaction is continued for 2 h, then filtered, the filter cake is washed with deionized water and anhydrous ethanol for 4 times respectively, and vacuum dried at 70°C for 2 h to obtain calcium-based diatomite.
[0026] S2: 60 g of 5-hydroxyisophthalic acid, 50 g of calcium-based diatomite, and 2 L of deionized water are added to the reaction kettle, 7 g of sodium hexadecyl sulfate is dissolved in 120 mL of 80 wt% ethanol solution and then added to the reaction kettle, stirred at 130°C and 500 r / min for 2 h, 50 g of magnesium chloride is added to the reaction kettle, and the stirring reaction is continued for 5 h, then filtered, the filter cake is washed with deionized water and anhydrous ethanol for 4 times respectively, and vacuum dried at 70°C for 2 h to obtain molecular sieve precursor powder.
[0027] S3: 70 g of chitosan, 200 mL of 3-mercaptopropyltrimethoxysilane, and 400 mL of ethanol are added to the reaction kettle, stirred at 70°C and 600 r / min for 2 h, filtered, the filter cake is washed with deionized water for 4 times, and vacuum dried at 70°C for 2 h to obtain a mercapto-coated layer; 50 g of the mercapto-coated layer, 30 g of the molecular sieve precursor powder, and 400 mL of a 30% mass fraction hydrogen peroxide solution are added to the reaction kettle, stirred at 25°C and 600 r / min for 2 h, then a 0.5 M sodium hydroxide solution is added to adjust the pH value to 9, filtered, the filter cake is washed with deionized water and ethanol for 4 times, vacuum dried at 70°C for 2 h, and the product is transferred to a muffle furnace, calcined at 600°C for 3 h under nitrogen protection to obtain sulfonated molecular sieve powder.
[0028] S4: The sulfonated molecular sieve powder is loaded into a 5A molecular sieve tower, and industrial-grade sulfur trioxide with a purity of 99% is introduced into the molecular sieve tower, and heavy metal impurities are removed by crystallization separation at -10 DEG C to obtain purified sulfur trioxide; 60 mL of methanol and 42 g of purified sulfur trioxide are added to a reaction kettle, stirred at 50 DEG C and 600 r / min for 40 min, then 50 mL of methanol is added, heated to 70 DEG C, and continues to react for 3 h, then 3 g of sulfonated molecular sieve powder is added for in-situ dehydration, and continues to stir for 2 h to reduce the water content to 0.05%, and then the dimethyl sulfate is obtained by vacuum rectification under a pressure of 80 KPa, thereby completing a green production process of dimethyl sulfate based on purification of sulfur trioxide.
[0029] Comparative Example 1: On the basis of Example 3, the calcium-based diatomite in step S2 is replaced by diatomite in step S1, and the remaining steps are unchanged, to obtain dimethyl sulfate.
[0030] Comparative Example 2: On the basis of Example 3, the molecular sieve precursor powder in step S3 is replaced by calcium-based diatomite in step S1 without step S2 treatment, and the remaining steps are unchanged, to obtain dimethyl sulfate.
[0031] Comparative Example 3: On the basis of Example 3, the sulfonated molecular sieve powder in step S4 is replaced by the molecular sieve precursor powder in step S2 without step S3 treatment, and the remaining steps are unchanged, to obtain dimethyl sulfate.
[0032] The dimethyl sulfates obtained in Examples 1-3 and Comparative Examples 1-3 are subjected to performance testing, the test method for sulfur trioxide content is GBT23855-2018 liquid sulfur trioxide, and the metal ion content is detected by inductively coupled plasma mass spectrometry (ICP-MS, ThermoX-7 series), as shown in Table 1: Table 1 Item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Sulfur trioxide content (%) 99.993 99.995 99.997 90.223 85.356 87.669 Metallic impurities (ug / g) 1.5 1.3 1.1 3.2 2.5 2.8 Dimethyl sulfate yield (%) 98.23 98.75 99.12 88.37 82.69 84.34 As can be seen from Table 1, the dimethyl sulfate prepared by the process has low metal impurities, high dimethyl sulfate yield and high sulfur trioxide content, indicating that the process provided by the application has high production efficiency for producing dimethyl sulfate and less heavy metal impurities in the production process.
[0033] The calcium-based diatomite in Comparative Example 1 is replaced by diatomite in step S1, the calcium-based diatomite is modified by calcium ions, the surface charge distribution and pore structure are optimized, the electrostatic attraction and ion exchange capacity for heavy metal ions are enhanced, the ordinary diatomite is not modified by calcium, mainly relies on physical adsorption, and the adsorption capacity for heavy metals is reduced, the calcium-based diatomite is impregnated by calcium chloride solution, the calcium ions in the diatomite skeleton form a cross-linked structure with the silicon-oxygen bond, the hardness is improved, and the ordinary diatomite has low hardness and is easy to break.
[0034] In the comparative example 2, the molecular sieve precursor powder is replaced by calcium-based diatomite, and a uniform magnesium metal microporous framework is formed by hydrothermal synthesis, which provides precise molecular sieve channels for subsequent sulfonation. The specific surface area, porosity and overall strength of the calcium-based bentonite are improved after the organic component is carbonized during calcination of the precursor powder.
[0035] In the comparative example 3, the sulfonated molecular sieve powder is replaced by the molecular sieve precursor powder. The core function of the sulfonated molecular sieve depends on the surface-modified sulfonic acid groups, which provide strong acid sites and enhance the ion exchange function of heavy metals. The molecular sieve precursor powder has not been subjected to sulfonation treatment and lacks sulfonic acid groups, resulting in a reduced density of acid sites. The sulfonic acid groups in the sulfonated molecular sieve can precisely adsorb specific ions, while the precursor powder only relies on unmodified channels for physical adsorption, resulting in a lower removal effect of heavy metals.
[0036] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, which can be understood by those of ordinary skill in the art.
Claims
1. A green production process of dimethyl sulfate based on sulfur trioxide purification, characterized in that, It comprises the following steps: The sulfonated molecular sieve powder is loaded into a 3-5A grade molecular sieve tower, and industrial grade sulfur trioxide with a purity of 98-99% is introduced into the molecular sieve tower to remove heavy metal impurities by crystallization separation at-15 to-10℃ to obtain purified sulfur trioxide; methanol and purified sulfur trioxide are added to a reaction kettle, stirred at 40-50℃ and 500-600r / min for 30-40min, then methanol is added again, heated to 60-70℃, and continue to react for 2-3h, then add sulfonated molecular sieve powder for in-situ dehydration, continue to stir for 1-2h, reduce the water content to 0.03-0.05%, and distill under reduced pressure at a pressure of 50-80KPa to obtain dimethyl sulfate, thus completing a green production process of dimethyl sulfate based on sulfur trioxide purification.
2. A green process for the production of dimethyl sulfate based on sulfur trioxide purification according to claim 1, characterized in that, The amount ratio of the methanol, sulfonated molecular sieve powder and purified sulfur trioxide is 90-110mL:38-42g:2-3g.
3. A green process for the production of dimethyl sulfate based on sulfur trioxide purification according to claim 1, characterized in that, The specific preparation steps of the sulfonated molecular sieve powder are as follows: Chitosan, 3-mercaptopropyltrimethoxysilane and ethanol are added to a reaction kettle, stirred at 60-70℃ and 500-600r / min for 1-2h, filtered and washed, and vacuum dried to obtain a mercapto-coated layer; The mercapto-coated layer, molecular sieve precursor powder and 20-30wt% hydrogen peroxide solution are added to a reaction kettle, stirred at 20-25℃ and 500-600r / min for 1-2h, then 0.5M sodium hydroxide solution is added to adjust the pH value to 9, filtered, washed, vacuum dried, and the product is transferred to a muffle furnace, calcined at 500-600℃ for 2-3h under nitrogen protection to obtain the sulfonated molecular sieve powder.
4. A green process for the production of dimethyl sulfate based on sulfur trioxide purification according to claim 3, characterized in that, The amount ratio of the chitosan, 3-mercaptopropyltrimethoxysilane and ethanol is 60-70g:120-200mL:300-400mL.
5. A green process for the production of dimethyl sulfate based on sulfur trioxide purification according to claim 3, characterized in that, The amount ratio of the mercapto-coated layer, molecular sieve precursor powder and hydrogen peroxide solution is 40-50g:20-30g:300-400mL.
6. A green process for the production of dimethyl sulfate based on sulfur trioxide purification according to claim 3, characterized in that, The specific preparation steps of the molecular sieve precursor powder are as follows: 5-Hydroxyisophthalic acid, calcium-based diatomite and deionized water are added to a reaction kettle, sodium dodecyl sulfate is dissolved in 100-120mL 70-80wt% ethanol solution and then added to the reaction kettle, stirred at 120-130℃ and 400-500r / min for 1-2h, magnesium chloride is added to the reaction kettle, and continue to stir for 4-5h, then filtered, washed, and vacuum dried to obtain the molecular sieve precursor powder.
7. A green process for the production of dimethyl sulfate based on sulfur trioxide purification according to claim 6, characterized in that, The amount ratio of the 5-hydroxyisophthalic acid, calcium-based diatomite, deionized water, sodium dodecyl sulfate, ethanol solution and magnesium chloride is 50-60g:40-50g:1-2L:5-7g:40-50g.
8. A green process for the production of dimethyl sulfate based on sulfur trioxide purification according to claim 6, characterized in that, The specific preparation steps of the calcium-based diatomite are as follows: The sodium bicarbonate solution with a mass fraction of 10-15% and diatomite are added into a reaction kettle, vacuum impregnated at 20-25 DEG C and 500-600 r / min for 2-3 h, then the calcium chloride solution with a mass fraction of 40-50% is added, and the reaction is continued for 1-2 h, then filtration is carried out, the filter cake is washed with deionized water and anhydrous ethanol for 2-4 times respectively, and vacuum drying is carried out at 60-70 DEG C for 1-2 h to obtain calcium-based diatomite.
9. A green process for the production of dimethyl sulfate based on sulfur trioxide purification according to claim 8, characterized in that, The sodium bicarbonate solution, diatomite and calcium chloride solution are used in a ratio of 100-120 mL: 50-60 g: 120-140 mL.