A heteropoly acid catalyst for preparing 2-chloro-epoxypropane and application thereof

Abstract

This invention discloses a method for preparing a heteropolyacid catalyst for the preparation of 2-chloro-propylene oxide. The catalyst obtained by this method, in conjunction with hydrogen peroxide, epoxidizes 2-chloropropylene at 30°C-50°C to prepare 2-chloro-propylene oxide. The catalyst is a heteropolyacid with a C2... m H n N x Z a M b O y Here, m is 64-120, n is 127-325, x is 2-8, y is 5-94, a is 1-2, b is 1-18, Z is one of Si or P, and M is one of Nb, Mo, W, or Ta; the concentration of hydrogen peroxide is 20%-50%. This method operates under mild conditions, requires no additional substances, and produces a catalyst with good dispersibility, high stability, and easy recovery. This catalyst preparation method is simple, exhibits excellent performance in the production of 2-chloro-propylene oxide, and operates under relatively mild conditions, making it of great industrial application value.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of improved catalyst preparation technology, in particular to a preparation method of a heteropoly acid catalyst for preparing 2-chloro-epoxypropane and application thereof. BACKGROUND

[0002] Epoxy compounds are a kind of organic intermediates with high value in industry and commerce. Different epoxy compounds can be used as raw materials to prepare important materials such as epoxy resins, rubbers and the like with different functions, and 2-chloro-epoxypropane can be used to prepare high-performance polymer materials. There are relatively many methods for preparing epoxy compounds, such as chlorohydrination method, co-oxidation method, hydrogen peroxide method and cumene hydroperoxide method.

[0003] The chlorohydrination method is one of the methods with the largest production of epoxy organic compounds in industrial production at present, which uses chlorine, olefin and alkali to obtain epoxy organic compounds, and the whole process includes three steps. First, chlorine reacts with water to generate hypochlorous acid, then hypochlorous acid reacts with olefin to obtain chlorohydrin, and finally chlorohydrin reacts with alkali to remove chlorine and hydrogen to obtain epoxy organic compounds. The method needs to use chlorine as raw material, which will cause harm to the environment and human body; and the reaction of water and chlorine not only produces hypochlorous acid, but also produces hydrochloric acid, so the atomic utilization rate is low; at the same time, due to the generation of hydrochloric acid, a large amount of acidic wastewater is produced, which increases the water treatment cost.

[0004] The co-oxidation method includes ethylbenzene co-oxidation method (PO / SM) and isobutane co-oxidation method (PO / MTBE), which respectively perform co-oxidation reaction of ethylbenzene or isobutane and olefin to obtain styrene or tert-butyl alcohol, and simultaneously produce epoxy organic compounds. The method can simultaneously obtain styrene or tert-butyl alcohol which is widely used in industry, but the product and the co-product need to be separated subsequently, which increases the post-treatment cost.

[0005] The cumene hydroperoxide method uses cumene hydroperoxide to directly epoxidize olefin to obtain epoxy organic compounds. The method has high selectivity, needs to use cumene hydroperoxide, and α,α-dimethylbenzyl alcohol is generated in the reaction process, which is recovered, hydrogenated and reduced to isopropylbenzene, oxidized to cumene hydroperoxide, and finally added to the reaction again. The production cost is high, and there is a certain safety hazard. Patent CN105272941A discloses a preparation method of epoxypropane, and the principle is the cumene hydroperoxide method. Although the yield is high, the method needs to input a large amount of olefin raw material, and in order to save raw materials, the olefin raw material needs to be recovered and purified, which has high cost.

[0006] The hydrogen peroxide process utilizes hydrogen peroxide to directly epoxidize olefins, yielding epoxide compounds. This method offers high selectivity, and the reaction directly produces water, making it environmentally friendly. Furthermore, the reaction conditions are relatively mild, making it suitable for industrial production. However, its drawbacks include technical instability and stringent requirements for catalysts. AV Sulimov et al. (Reference: Sulimov AV, Danov SM, Ovcharova AV, et al. Physicochemical relationships of the synthesis of epoxy compounds[J]. Russian Journal of Applied Chemistry, 2015, 88: 89-96.) used titanium silicate molecular sieves as catalysts and methanol as solvents to epoxidize propylene, allyl alcohol, and propylene chloride, achieving high yields. However, this reaction requires periodic combustion regeneration of the catalyst in industrial applications. Patent CN 103459378A uses titanium silicate molecular sieves as catalysts, alcohols, and non-reactive co-solvents as solvents, while simultaneously mixing iron ions into the olefin feedstock to epoxidize propylene compounds, yielding epoxidized products. Compared to the previous method, this method does not require periodic combustion regeneration of the catalyst, but it does require cleaning with a regeneration cleaning solution. Additionally, the addition of iron ions during the reaction increases costs to some extent.

[0007] However, among the methods for preparing 2-chloro-propylene oxide, there is no method for the epoxidation of 2-chloropropene; only the chlorination reaction of propylene oxide yields 2-chloro-propylene oxide. This method was proposed by Krosley et al. (Reference: Krosley KW, Gleicher GJ, Clapp G E. Radical reactions of epoxides. Chlorine-atomabstraction from alpha- and beta-chloro epoxides by the triphenyltin radical [J]. The Journal of Organic Chemistry, 1992, 57(3): 840-844.). It uses tert-butyl hypochlorite and light to convert 2-chloropropene to 2-chloro-propylene oxide at 0°C. The yield of this reaction is low, only 75%, and there are many side reactions, resulting in poor selectivity.

[0008] Therefore, it is necessary to design a catalyst that can be used for the epoxidation reaction of 2-chloropropylene to prepare 2-chloro-epoxypropane, while reducing the cost of purification and cleaning the catalyst in the post-reaction treatment, and ensuring that the conversion rate and yield remain at a high level after 1000 hours of operation.

[0009] A heterogeneous catalyst with high activity, easy regeneration, low cost, and long cycle time was prepared for the epoxidation of 2-chloropropylene to produce 2-chloro-epoxypropane. Summary of the Invention

[0010] A method for preparing a heteropolyacid catalyst for the preparation of 2-chloro-epoxypropane, the catalyst having a composition of C m H n N x Z a M b O y The catalyst obtained by this method, in conjunction with hydrogen peroxide, epoxidizes 2-chloropropene at 30℃-50℃ to yield 2-chloro-epoxypropane. The catalyst preparation method involves the following three steps:

[0011] Step 1: Prepare a 0.5 mol / L aqueous solution of 10-20 mmol soluble Z salt, denoted as solution A; prepare a 2 mol / L aqueous solution of 100-120 mmol soluble M salt by adding water, then add 10 ml of 4 mol / L hydrochloric acid or hydrobromic acid in three batches, 3 minutes apart, while stirring vigorously to obtain solution B; pour solution A into solution B, then stir to mix well and adjust the pH to 4-7, preferably to 5, by adding 4 mol / L hydrochloric acid or hydrobromic acid dropwise. -6, stir continuously for 0.5h-3h, preferably 1h-2h; then add 2000-2400mmol of soluble halide, stir for 5min-24h, preferably 15min-18h, and filter out the solid; then add the solid to 200ml of water, filter out the water-insoluble solid, add 0.2mol of soluble halide to the filtrate, and filter again; wash the solid sequentially with 2mol / L of the same soluble halide solution as before and deionized water, and dry at room temperature to obtain solid C.

[0012] Step 2: Take 6 mmol of solid C obtained in Step 1 and dissolve it in 300 ml of deionized water (if insoluble matter is present, remove it by filtration). Add alkaline solution to adjust the pH to 8-10, preferably 9-9.5; then stir for 10-60 min, preferably 15-30 min. Next, add 2.5 mol of soluble halide and continuously add alkaline solution to adjust the pH to 8-10, preferably 9-9.5; then filter to obtain the precipitate, and wash the solid successively with 2 mol / L of the previously prepared halide solution and deionized water. After drying at room temperature, obtain solid D.

[0013] Step 3: Take 5.1 mmol of the solid D obtained in Step 2 and dissolve it in 250 ml of 30% hydrogen peroxide solution; then add a solution containing 6 mmol of alkyl ammonium halide and 50 ml of alcohol solvent, stir vigorously in a water bath at 30℃-50℃ for 1 h-6 h, and then filter, preferably at 40℃-45℃ for 3 h-5 h; wash the solid twice with 50 ml of water at 30℃-50℃, 25 ml of alcohol solvent, and 25 ml of diethyl ether, respectively; finally, vacuum dry at 30℃-50℃ for 8 h-24 h to obtain the final catalyst E, preferably at 40℃-45℃ for 12 h-18 h.

[0014] Here, Z represents one of Si or P, M represents one of Nb, Mo, W, or Ta, m is 64-120, n is 127-325, x is 2-8, y is 5-94, a is 1-2, and b is 1-18. Soluble Z salts are one of silicates or phosphates. Silicates include sodium silicate, potassium silicate, lithium silicate, and ammonium silicate; phosphates include sodium monohydrogen phosphate, sodium dihydrogen phosphate, sodium phosphate, potassium monohydrogen phosphate, potassium dihydrogen phosphate, potassium phosphate, ammonium monohydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, and lithium dihydrogen phosphate. Soluble M salts are one of niobates, molybdates, tungstates, and tantalates. Niobates include sodium niobate and potassium niobate; molybdates include sodium molybdate, potassium molybdate, and ammonium molybdate; tungstates include sodium tungstate, potassium tungstate, and ammonium tungstate; and tantalates include sodium tantalate, potassium tantalate, and ammonium tantalate. Soluble halides are one or more of sodium chloride, potassium chloride, ammonium chloride, sodium bromide, potassium bromide, and ammonium bromide. Alkaline solutions include one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate. Alkyl ammonium halides include, but are not limited to, (C...) m H 2m+1 )4NX、(C n H 2n+1 The solvent is one or more of the following: 2(CH3)2NX, where m is 4-10, n is 8-18, and X is Cl or Br. The alcohol solvent includes, but is not limited to, one or more of the following: methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol. The final catalyst contains Z and M at mass fractions of 0.53%-6.74% and 10.11%-61.96%, respectively, preferably 1%-5% and 15%-40%.

[0015] Before the reaction begins, 2-chloropropene, catalyst, and solvent are added to a pressure-resistant bottle, while the water bath temperature is controlled at around 0°C, and nitrogen is introduced as a protective gas. Then, the temperature is raised to 30°C-50°C, preferably 40°C-45°C. After that, hydrogen peroxide with a content of 20%-50%, preferably 30%-40%, is added dropwise. The hydrogen peroxide is added dropwise over 20 min-60 min, preferably 30 min-35 min. After the addition is complete, the reaction continues for 0.5 h-8 h, preferably 1 h-5 h. The molar ratio of 2-chloropropene to hydrogen peroxide to catalyst is 2-6:1:0.02, preferably 3-4:1:0.02; the mass ratio of 2-chloropropene to solvent in the reaction is 1:3-18, preferably 1:5-15; the nitrogen gas is one of industrial nitrogen, pure nitrogen, and high-purity nitrogen, preferably high-purity nitrogen; the reaction pressure is 0.1MPa-0.3MPa, preferably 0.15MPa-0.2MPa; the solvent in the reaction is one or more of methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, acetonitrile, tert-butanol, tert-amyl alcohol, 1,4-dioxane, tetrahydrofuran, 1,2-dichloroethane, toluene, o-xylene, m-xylene, p-xylene, mesitylene, etc.

[0016] This method operates under mild conditions, requires no additional substances, and produces a catalyst with good dispersibility, high stability, and easy recovery. The catalyst preparation method is simple, exhibits excellent performance in the production of 2-chloro-propylene oxide, and operates under relatively mild conditions, making it highly valuable for industrial applications.

[0017] Advantages of this invention:

[0018] The catalyst described in this invention can minimize the increase in catalyst regeneration costs. The catalyst can be recycled for 1000 hours to maintain a yield and selectivity of no less than 80%, and the post-processing cost of the obtained product is low. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to specific embodiments. The scope of protection of the present invention includes, but is not limited to, the following embodiments. Any modifications to the details and form of the technical solution of the present invention without departing from the meaning and scope of this application shall fall within the scope of protection of the present invention.

[0020] Example 1

[0021] Catalyst preparation:

[0022] The first step involves preparing a 0.5 mol / L aqueous solution of 20 mmol sodium silicate, denoted as solution A1. Then, 120 mmol sodium tungstate is dissolved in water to prepare a 2 mol / L aqueous solution. This solution is then added in three batches of 10 ml of 4 mol / L hydrochloric acid (divided into three equal volumes), with each addition occurring 3 minutes apart, accompanied by vigorous stirring, to obtain solution B1. Solution A1 is poured into solution B1, and the mixture is stirred until homogeneous. The pH is adjusted to 5.5 by adding 4 mol / L hydrochloric acid dropwise, and stirring is continued for 2 hours. Next, 2400 mmol of sodium chloride is added, followed by stirring for 30 minutes, and the solid is filtered out. The solid is then added to 200 ml of water, and the water-insoluble solid is filtered out. 0.2 mol of sodium chloride solid is added to the filtrate, and the mixture is filtered again. The solid is washed sequentially with 2 mol / L sodium chloride solution and deionized water. The filtrate and washings are collected and dried at room temperature to obtain solid C1.

[0023] In the second step, 6 mmol of C1 was dissolved in 300 ml of deionized water. After filtration to remove insoluble matter, 1 mol / L sodium carbonate solution was added to adjust the pH to 9. The mixture was then stirred for 15 min. Next, 2.5 mol of sodium chloride solid was added, and 1 mol / L sodium carbonate solution was continuously added dropwise to adjust the pH to 9. The precipitate was then obtained by suction filtration and washed with 2 mol / L sodium chloride solution and deionized water, respectively. After drying at room temperature, solid D1 was obtained.

[0024] In the third step, 5.1 mmol of D1 was dissolved in 250 ml of 30% hydrogen peroxide solution; then, 50 ml of ethanol solution containing 6 mmol of tetrabutylammonium chloride was added, and the mixture was stirred vigorously in a water bath at 40°C for 3 hours before filtration. The solid was washed twice with 50 ml of water at 40°C, 25 ml of ethanol, and 25 ml of diethyl ether, respectively; finally, it was vacuum dried at 40°C for 12 hours to obtain the final catalyst E1. Atomic absorption spectroscopy analysis showed that the mass fractions of silicon and tungsten in catalyst E1 were 3.18% and 31.22%, respectively.

[0025] Comparative Example 1

[0026] The first two steps of catalyst preparation (process and conditions) were the same as in Example 1. The difference was that the third step of catalyst preparation was omitted, yielding only D1. Atomic absorption spectroscopy analysis revealed that the mass fractions of silicon and tungsten in catalyst D1 were 1.66% and 65.11%, respectively.

[0027] Comparative Example 2

[0028] The first step of catalyst preparation (process and conditions) was the same as in Example 1. The difference was that the second and third steps of catalyst preparation were omitted, yielding only C1. Atomic absorption spectroscopy analysis revealed that the mass fractions of silicon and tungsten in catalyst C1 were 1.80% and 64.77%, respectively.

[0029] Comparative Example 3

[0030] The catalyst preparation (process and conditions) was the same as in Example 1, except that in the third step of catalyst preparation, "then add 50 ml of ethanol solution containing 6 mmol tetrabutylammonium chloride" was replaced with "then add 50 ml of ethanol solution containing 6 mmol tetramethylammonium chloride". The resulting catalyst was designated E1-3. Atomic absorption spectroscopy analysis showed that the mass fractions of silicon and tungsten in catalyst E1-3 were 4.45% and 43.68%, respectively.

[0031] Comparative Example 4

[0032] The first step of catalyst preparation (process and conditions) is the same as in Example 1. The difference is that the first step of catalyst preparation, which previously stated "First, 20 mmol of sodium silicate is prepared into a 0.5 mol / L aqueous solution, denoted as solution A1; 120 mmol of sodium tungstate is prepared into a 2 mol / L aqueous solution after adding water; then 2 ml of 4 mol / L hydrochloric acid is added in three batches, each 3 minutes apart, with vigorous stirring to obtain solution B1," is replaced with "First, 20 mmol of potassium silicate is prepared into a 0.5 mol / L aqueous solution, denoted as solution A1-4; 120 mmol of potassium chromate is prepared into a 2 mol / L aqueous solution after adding water; then 2 ml of 4 mol / L hydrochloric acid is added in three batches, each 3 minutes apart, with vigorous stirring to obtain solution B1-4." The remaining preparation steps are the same as in Example 1. However, no solid precipitates after the addition of sodium chloride in the first step, thus the final catalyst cannot be obtained.

[0033] Comparative Example 5

[0034] The catalyst preparation (process and conditions) was the same as in Example 1, except that the first step in catalyst preparation, "firstly, 20 mmol of sodium silicate was prepared into a 0.5 mol / L aqueous solution, denoted as solution A1", was replaced with "firstly, 20 mmol of sodium sulfate was prepared into a 0.5 mol / L aqueous solution, denoted as solution A1-5". The remaining preparation steps were the same as in Example 1. The final catalyst was denoted as E1-5. Atomic absorption spectroscopy analysis showed that the mass fractions of sulfur and tungsten in catalyst E1-5 were 3.61% and 31.08%, respectively.

[0035] Example 2

[0036] First, 10 mmol of sodium dihydrogen phosphate was prepared into a 0.5 mol / L aqueous solution, denoted as solution A2. 100 mmol of sodium molybdate was prepared into a 2 mol / L aqueous solution by adding water. Then, 10 ml of 4 mol / L hydrochloric acid (divided into three equal volumes) was added in three batches, each 3 minutes apart, with vigorous stirring, to obtain solution B2. Solution A2 was poured into solution B2, and the mixture was stirred until homogeneous. The pH was adjusted to 5.5 by adding 4 mol / L hydrochloric acid dropwise, and stirring was continued for 1.5 hours. Then, 2000 mmol of potassium chloride was added, and the mixture was stirred for 45 minutes, followed by filtration to obtain the solid. Next, the solid was added to 200 ml of water, and the water-insoluble solid was filtered out. 0.2 mol of potassium chloride was added to the filtrate, and the mixture was filtered again. The solid was washed successively with 2 mol / L potassium chloride solution and deionized water. The filtrate and washings were collected and dried at room temperature to obtain solid C2.

[0037] In the second step, 6 mmol of C2 was dissolved in 300 ml of deionized water. After filtration to remove insoluble matter, 1 mol / L potassium carbonate solution was added to adjust the pH to 9. The mixture was then stirred for 20 min. Next, 2.5 mol of potassium chloride was added, and 1 mol / L potassium carbonate solution was continuously added dropwise to adjust the pH to 9. The precipitate was then obtained by suction filtration and washed with 2 mol / L potassium chloride solution and deionized water, respectively. After drying at room temperature, solid D2 was obtained.

[0038] In the third step, 5.1 mmol of D2 was dissolved in 250 ml of 30% hydrogen peroxide solution; then, 50 ml of methanol solution containing 6 mmol of tetrapentylammonium chloride was added, and the mixture was stirred vigorously in a water bath at 50°C for 4 hours before filtration. The solid was washed twice with 50 ml of water at 50°C, 25 ml of methanol, and 25 ml of diethyl ether, respectively; finally, it was dried under vacuum at 40°C for 15 hours to obtain the final catalyst E2. Atomic absorption spectroscopy analysis showed that the mass fractions of phosphorus and molybdenum in catalyst E2 were 1.99% and 18.55%, respectively.

[0039] Example 3

[0040] The catalyst preparation (process and conditions) was the same as in Example 2, except that in the third step of catalyst preparation, "then add 50 ml of methanol solution containing 6 mmol tetrapentylammonium chloride" was replaced with "then add 50 ml of ethanol solution containing 6 mmol dioctyldimethylammonium chloride". The final catalyst was designated E3. Atomic absorption spectroscopy analysis showed that the mass fractions of phosphorus and molybdenum in catalyst E3 were 2.11% and 19.61%, respectively.

[0041] Example 4

[0042] The catalyst preparation (process and conditions) was the same as in Example 1. The difference was that the first step in catalyst preparation, "First, 20 mmol of sodium silicate was prepared into a 0.5 mol / L aqueous solution, denoted as solution A1; 120 mmol of sodium tungstate was prepared into a 2 mol / L aqueous solution after adding water, and then 2 ml of 4 mol / L hydrochloric acid was added in three batches, each 3 minutes apart, with vigorous stirring to obtain solution B1," was replaced with "First, 10 mmol of potassium silicate was prepared into a 0.5 mol / L aqueous solution, denoted as solution A4; 110 mmol of sodium tungstate was prepared into a 2 mol / L aqueous solution after adding water, and then 2 ml of 4 mol / L hydrochloric acid was added in three batches, each 3 minutes apart, with vigorous stirring to obtain solution B4." The remaining preparation steps were the same as in Example 1. The final catalyst was denoted as E4. Atomic absorption spectroscopy analysis showed that the mass fractions of silicon and tungsten in catalyst E4 were 2.08% and 40.94%, respectively.

[0043] Example 5

[0044] The catalyst preparation (process and conditions) was the same as in Example 4, except that in the third step of catalyst preparation, "then add 50 ml of methanol solution containing 6 mmol tetrapentylammonium chloride" was replaced with "then add 50 ml of n-butanol solution containing 6 mmol dioctadecyldimethylammonium chloride". The remaining preparation steps were the same as in Example 1. The final catalyst was designated E5. Atomic absorption spectroscopy analysis showed that the mass fractions of silicon and tungsten in catalyst E5 were 1.11% and 21.76%, respectively.

[0045] Example 6

[0046] First, 10 mmol of sodium phosphate was prepared into a 0.5 mol / L aqueous solution, denoted as solution A6. 100 mmol of sodium niobate was prepared into a 2 mol / L aqueous solution by adding water. Then, 10 ml of 4 mol / L hydrobromic acid (divided into three equal volumes) was added in three batches, each 3 minutes apart, with vigorous stirring, to obtain solution B6. Solution A6 was poured into solution B6, and the mixture was stirred until homogeneous. The pH was adjusted to 5.5 by adding 4 mol / L hydrobromic acid dropwise, and stirring was continued for 1 hour. Then, 2000 mmol of sodium bromide was added, and the mixture was stirred for 60 minutes, and the solid was filtered out. Next, the solid was added to 200 ml of water, and the water-insoluble solid was filtered out. 0.2 mol of sodium bromide was added to the filtrate, and the mixture was filtered again. The solid was washed successively with 2 mol / L potassium chloride solution and deionized water. The filtrate and washings were collected and dried at room temperature to obtain solid C6.

[0047] In the second step, 30g of C6 was dissolved in 300ml of deionized water. After filtration to remove insoluble matter, 0.1mol / L sodium hydroxide solution was added to adjust the pH to 9. The mixture was then stirred for 20min. Next, 2.5mol of sodium bromide was added, and 0.1mol / L sodium hydroxide solution was continuously added dropwise to adjust the pH to 9. The precipitate was then obtained by suction filtration and washed with 2mol / L sodium bromide solution and deionized water, respectively. After drying at room temperature, solid D6 was obtained.

[0048] In the third step, 15g of D6 was dissolved in 250ml of 30% hydrogen peroxide solution; then, 50ml of n-butanol solution containing 6mmol of didecyldimethylammonium bromide was added, and the mixture was stirred vigorously in a water bath at 40℃ for 4 hours before filtration. The solid was washed twice with 50ml of water at 40℃, 25ml of n-butanol, and 25ml of diethyl ether, respectively; finally, it was vacuum dried at 40℃ for 16 hours to obtain the final catalyst E6. Atomic absorption spectroscopy analysis showed that the mass fractions of phosphorus and niobium in catalyst E6 were 1.49% and 19.21%, respectively.

[0049] Example 7

[0050] The catalyst preparation (process and conditions) was the same as in Example 6, except that in the third step of catalyst preparation, "then add 50 ml of n-butanol solution containing 6 mmol of didecyldimethylammonium bromide" was replaced with "then add 50 ml of ethanol solution containing 6 mmol of didodecyldimethylammonium bromide". The remaining preparation steps were the same as in Example 6. The final catalyst was designated E7. The mass fractions of phosphorus and niobium in catalyst E7 were 1.37% and 17.58%, respectively.

[0051] Example 8

[0052] First, 10 mmol of sodium silicate was prepared into a 0.5 mol / L aqueous solution, denoted as solution A8. 100 mmol of sodium niobate was prepared into a 2 mol / L aqueous solution by adding water. Then, 10 ml of 4 mol / L hydrobromic acid (divided into three equal volumes) was added in three batches, each 3 minutes apart, with vigorous stirring, to obtain solution B8. Solution A8 was poured into solution B8, and the mixture was stirred until homogeneous. The pH was adjusted to 5.5 by adding 4 mol / L hydrobromic acid dropwise, and stirring was continued for 1 hour. Then, 2000 mmol of sodium bromide was added, and the mixture was stirred for 60 minutes, and the solid was filtered out. Next, the solid was added to 200 ml of water, and the water-insoluble solid was filtered out. 0.2 mol of sodium bromide was added to the filtrate, and the mixture was filtered again. The solid was washed successively with 2 mol / L potassium chloride solution and deionized water. The filtrate and washings were collected and dried at room temperature to obtain solid C8.

[0053] In the second step, 30g of C8 was dissolved in 300ml of deionized water. After filtration to remove insoluble matter, 0.1mol / L sodium hydroxide solution was added to adjust the pH to 9. The mixture was then stirred for 20min. Next, 2.5mol of sodium bromide was added, and 0.1mol / L sodium hydroxide solution was continuously added dropwise to adjust the pH to 9. The precipitate was then obtained by suction filtration and washed with 2mol / L sodium bromide solution and deionized water, respectively. After drying at room temperature, solid D8 was obtained.

[0054] In the third step, 15g of D8 was dissolved in 250ml of 30% hydrogen peroxide solution; then, 50ml of n-butanol solution containing 6mmol of didecyldimethylammonium bromide was added, and the mixture was stirred vigorously in a water bath at 40℃ for 4 hours before filtration. The solid was washed twice with 50ml of water at 40℃, 25ml of n-butanol, and 25ml of diethyl ether, respectively; finally, it was vacuum dried at 40℃ for 16 hours to obtain the final catalyst E8. Atomic absorption spectroscopy analysis showed that the mass fractions of silicon and niobium in catalyst E8 were 1.64% and 23.25%, respectively.

[0055] Example 9

[0056] The catalyst preparation (process and conditions) was the same as in Example 8, except that in the third step of catalyst preparation, "then add 50 ml of n-butanol solution containing 6 mmol of didecyldimethylammonium bromide" was replaced with "then add 50 ml of tert-butanol solution containing 6 mmol of didodecyldimethylammonium bromide". The remaining preparation steps were the same as in Example 6. The final catalyst was designated E9. Atomic absorption spectroscopy analysis showed that the mass fractions of silicon and niobium in catalyst E9 were 1.49% and 21.18%, respectively.

[0057] Example 10

[0058] The catalyst preparation (process and conditions) was the same as in Example 1. The difference was that the first step in catalyst preparation, "First, 20 mmol of sodium silicate was prepared into a 0.5 mol / L aqueous solution, denoted as solution A1; 120 mmol of sodium tungstate was prepared into a 2 mol / L aqueous solution after adding water, and then 10 ml of 4 mol / L hydrochloric acid (divided into 3 equal volumes) was added in three batches, each 3 minutes apart, with vigorous stirring to obtain solution B1," was replaced with "First, 10 mmol of sodium silicate was prepared into a 0.5 mol / L aqueous solution, denoted as solution A10; 80 mmol of sodium tantalate was prepared into a 2 mol / L aqueous solution after adding water, and then 2 ml of 4 mol / L hydrochloric acid (divided into 3 equal volumes) was added in three batches, each 3 minutes apart, with vigorous stirring to obtain solution B10." The remaining preparation steps were the same as in Example 1. The final catalyst was denoted as E10. Atomic absorption spectroscopy analysis showed that the mass fractions of silicon and tantalum in catalyst E10 were 1.75% and 33.78%, respectively.

[0059] Example 11

[0060] The catalysts and raw materials obtained in Examples 1-10 and Comparative Examples 1-5 were added to the reaction flasks according to the following addition methods:

[0061] Before the reaction began, 2.5 mmol of 2-chloropropene, 10 mmol of catalyst, and 2 mL of ethyl acetate were added to the reaction flask. The water bath temperature was maintained at approximately 0-1 °C. After sealing, high-purity nitrogen was introduced as a protective gas, and the pressure was increased to 0.2 MPa. The temperature was then raised to 40 °C. 51 mL of 30% hydrogen peroxide was then added dropwise, completing the addition after 30 min. The reaction continued for another 2 h. The resulting mixture was filtered and allowed to stand until the aqueous and oil phases clearly separated. The oil phase was separated, and anhydrous calcium chloride was added and stirred for 30 min. The resulting anhydrous oil phase was then obtained by centrifugation. Finally, the selectivity and yield of 2-chloro-propylene oxide were determined by gas chromatography. The filtered solid catalyst was washed with methanol, dried, and then subjected to a cycling test. The experimental results are shown in the table below.

[0062]

[0063]

[0064] Note: "-" indicates that it has not been tested or cannot be tested.

[0065] The results show that the heteropolyacid catalyst plays a major role in this reaction. In the reaction, the addition of hydrogen peroxide causes the catalyst to first react with hydrogen peroxide to form a peroxide heteropolyacid ligand, which then epoxidizes 2-chloropropene to 2-chloro-epoxypropane, lowering the required activation energy and allowing the reaction to proceed rapidly. Simultaneously, the catalyst is relatively stable, achieving a yield and selectivity of over 80% for 1000 consecutive hours.

Claims

1. A heteropolyacid catalyst for the preparation of 2-chloro-epoxypropane, having a composition of C2... m H n N x Z a M b O y Z is selected from one or two of Si and P, and M is one or more of Nb, Mo, W, and Ta. m is 40-160 (preferably 64-120), n is 112-360 (preferably 127-325), x is 1-10 (preferably 2-8), a is 0.1-5 (preferably 1-2), b is 0.1-30 (preferably 1-18), and the value of y satisfies the oxygen atom ratio required for the valence state of the preceding element (preferably y is 3-120 (more preferably 5-94)). The preparation method of its catalyst consists of three steps: The first step is as follows: First, prepare a 0.01-1 mol / L (preferably 0.1-0.8 mol / L) aqueous solution of 10-20 mmol of soluble Z salt, denoted as solution A; prepare a 0.1-5 mol / L (preferably 1-3 mol / L) aqueous solution of 100-120 mmol of soluble M salt after adding water, then add 2-20 mL (preferably 5-16 mL) of 1-6 mol / L (preferably 2-5 mol / L) hydrochloric acid and / or hydrobromic acid in 2-5 portions, with each addition spaced 0.5-5 min (preferably 1-4 min) apart, while stirring, to obtain solution B; mix solution A and solution B, then stir until homogeneous and pass through a purging station. Adjust the pH to 4-7, preferably 5-6, by adding dropwise 0.1-5 mol / L (preferably 1-3 mol / L) hydrochloric acid and / or hydrobromic acid, and continue stirring for 0.5-3 h, preferably 1-2 h; then add 2000-2400 mmol of soluble halide, and stir for 5 min-24 h, preferably 15 min-18 h, and filter out the solid; then add the solid to 30-500 mL (preferably 50-300 mL) of water, filter out the water-insoluble solid, add 0.01-1 mol / L (preferably 0.1-0.5 mol / L) of soluble halide to the filtrate, and filter again; wash the solid sequentially with 30-500 mL of the same 0.1-10 mol / L (preferably 1-5 mol / L) soluble halide solution and deionized water, collect the filtrate and washings, and dry at room temperature to obtain solid C; The second step is as follows: Take 3-50 mmol (preferably 5-30 mmol) of solid C obtained in the first step and dissolve it in 50-800 mL (preferably 100-500 mL) of deionized water. (If there are insoluble substances, filter to remove them.) Add an alkaline solution to adjust the pH to 8-10, preferably 9-9.

5. Then stir for 10-60 min, preferably 15-30 min. Next, add 0.1-8 mol (preferably 1-5 mol) of soluble halide solid and continuously add an alkaline solution to adjust the pH to 8-10, preferably 9-9.

5. Then filter to obtain a precipitate and wash the solid sequentially with 0.1-10 mol / L (preferably 1-5 mol / L) of the previously prepared halide solution and deionized water. After drying at room temperature, solid D is obtained. The third step is as follows: Take 0.1-10 mmol (preferably 1-8 mmol) of the solid D obtained in the second step and dissolve it in 50-800 mL (preferably 100-500 mL) of 5%-50% (preferably 10%-40%) hydrogen peroxide aqueous solution; then add a solution containing 0.1-10 mmol (preferably 1-8 mmol) of alkyl ammonium halide and 10-100 mL (preferably 30-80 mL) of alcohol solvent, and stir at 30℃-50℃ for 1 minute. After 6 hours (preferably 40℃-45℃, 3 hours-5 hours), the solid was filtered. The solid was then washed sequentially with 10-100 ml (preferably 30-80 mL) of water at 30℃-50℃, 10-50 ml (preferably 20-30 mL) of alcohol solvent, and 10-50 ml (preferably 20-30 mL) of diethyl ether. Finally, the solid was vacuum dried at 30℃-50℃ for 8 hours-24 hours (preferably 40℃-45℃, 12 hours-18 hours) to obtain the final catalyst E.

2. The catalyst preparation method according to claim 1, characterized in that, The soluble Z salt is one or more of silicates and phosphates; wherein the silicate is one or more of sodium silicate, potassium silicate, lithium silicate, and ammonium silicate; and the phosphate is one or more of sodium monohydrogen phosphate, sodium dihydrogen phosphate, sodium phosphate, potassium monohydrogen phosphate, potassium dihydrogen phosphate, potassium phosphate, ammonium monohydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, and lithium dihydrogen phosphate.

3. The catalyst preparation method according to claim 1, characterized in that, The soluble M salt is one or more of niobate, molybdate, tungstate, and tantalate; Niobates include one or two of sodium niobate, potassium niobate, etc.; molybdates include one or two or more of sodium molybate, potassium molybate, ammonium molybate, etc.; tungstates include one or two or more of sodium tungstate, potassium tungstate, ammonium tungstate, etc.; tantalates include one or two or more of sodium tantalate, potassium tantalate, ammonium tantalate, etc.

4. The catalyst preparation method according to claim 1, characterized in that, The soluble halide is one or more of sodium chloride, potassium chloride, ammonium chloride, sodium bromide, potassium bromide, and ammonium bromide.

5. The catalyst preparation method according to claim 1, characterized in that, The alkaline solution comprises one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate, with a mass concentration of 0.01-10 mol / L (preferably 0.1-5 mol / L). The alkyl ammonium halide includes, but is not limited to, (C) m H 2m+1 )4NX、(C n H 2n+1 One or more of the following: )2(CH3)2NX, where m is a positive integer from 4 to 10, n is a positive integer from 8 to 18, and X is one or two of Cl or Br; The alcohol solvents include, but are not limited to, one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, etc.

6. The preparation method according to claim 1, characterized in that, The mass fractions of Z and M in the catalyst are 0.53%-6.74% and 10.11%-61.96%, respectively, preferably 1%-5% and 15%-40%.

7. The application of a catalyst according to any one of claims 1-6, characterized in that: Under the combined action of the catalyst and hydrogen peroxide, 2-chloropropene can be epoxidized at 30℃-50℃ to obtain 2-chloro-epoxypropane.

8. The application of the catalyst according to claim 7, characterized in that, Before the reaction begins, 2-chloropropene, catalyst, and solvent are added to a container, while the temperature is controlled at 0-4℃ (preferably 0-2℃), and nitrogen is introduced as a protective gas. Then the temperature is raised to 30℃-50℃, preferably 40℃-45℃. After that, hydrogen peroxide with a mass content of 20%-50%, preferably 30%-40%, is added dropwise. The hydrogen peroxide is added dropwise over 20min-60min, preferably 30min-35min. After the addition is complete, the reaction continues for 0.5h-8h, preferably 1h-5h.

9. The application according to claim 7, characterized in that, In the reaction, the molar ratio of 2-chloropropene to hydrogen peroxide to catalyst is 2-6:1:0.02, preferably 3-4:1:0.02; In the reaction, the mass ratio of 2-chloropropene to solvent is 1:3-18, preferably 1:5-15; The nitrogen gas is one or more of industrial nitrogen, pure nitrogen, and high-purity nitrogen, with high-purity nitrogen being preferred. The reaction pressure is 0.1MPa-0.3MPa, preferably 0.15MPa-0.2MPa.

10. The application of the catalyst according to claim 7, characterized in that, The solvent for the reaction is one or more of the following: methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, acetonitrile, tert-butanol, tert-amyl alcohol, 1,4-dioxane, tetrahydrofuran, 1,2-dichloroethane, toluene, o-xylene, m-xylene, p-xylene, mesitylene, etc.

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