Supported heteropoly acid catalysts, their preparation and process for preparing styrene oxide

Abstract

The invention discloses a synthesis method of epoxy styrene. The method adopts a heterogeneous catalytic process, uses styrene as raw material, uses graphene and metal oxide as precursor loaded heteropoly acid as catalyst, uses mixed phosphate as additive, uses organic solvent as condition, uses hydrogen peroxide as oxidant to directly generate epoxy styrene; after the reaction is completed, the reaction liquid is cooled, the solid catalyst in the reaction liquid is recovered by filtration or centrifugation and the like and is recycled. The composition of the composite catalyst is CoMn a Mg b O c / GS-PW12; the value range of a is 0.5-2; the value range of b is 0.1-0.8; c is the proportion of oxygen atoms required to meet the oxidation state of metal. The reaction method is simple, the cost is low, the reaction can be carried out at normal pressure, the catalyst has good catalytic activity, the service life is long, the recovery is easy, the recovery rate is high, the energy consumption is low, the environment is friendly, and the reaction yield is as high as 90% or more.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemical industry, and designs a supported polyoxometalate catalyst for catalytic oxidation synthesis of organic epoxides. BACKGROUND

[0002] Epoxystyrene is an important fine chemical product, as an important organic synthesis intermediate, it is widely used in the synthesis of levamisole hydrochloride, beta-phenylethanol, ultraviolet absorber and epoxy resin diluent, etc. At present, the methods of styrene epoxidation mainly include halogen alcohol epoxidation, inorganic acid salt epoxidation, organic peroxo acid epoxidation, alkyl hydroperoxide epoxidation, hydrogen peroxide epoxidation, air or oxygen epoxidation, etc. These methods can be used in industry.

[0003] Among them, the halogen alcohol process flow is complex, a large amount of wastewater is produced in the production process, causing environmental pollution, and seriously corroding the equipment. The oxidizing agent in the inorganic acid salt epoxidation method also has pollution problems, so their wide application is also limited. Most of the organic peracids have the defects of poor stability, easy decomposition, and must be refrigerated, and have the disadvantages of high price, long reaction period and high reaction temperature, which limit its marketization. The conversion rate of styrene and the yield of epoxystyrene in the alkyl hydroperoxide epoxidation method are low. Oxygen or air as oxidant, the reaction product is water, no pollution, is a very green oxidant, and its price is very low, therefore, oxygen as oxidant has been widely used, and has many applications in styrene epoxidation. However, the reaction needs to be carried out under pressure, which has certain safety hidden dangers and complex operation. When low concentration hydrogen peroxide (30%) is used as oxidant, water is the only by-product after reaction, which is a very promising oxidant, so many researchers choose it as the ideal oxidant for styrene epoxidation.

[0004] Polyoxometalate is a relatively effective catalyst for cyclohexene epoxidation, but this catalyst is often difficult to recover in liquid phase reaction, increasing the production cost. The POM catalyst after immobilization usually has the advantages of easy separation and recovery, so choosing a suitable carrier to load POM has become the focus of research at home and abroad. Patent CN202010792689.1 discloses a supported polyacid catalyst for styrene epoxidation reaction, but the yield of epoxystyrene is low, and air is continuously introduced during the reaction, so the reaction operation is complex; patent CN202211003599.5 discloses an Ag / SiC catalyst for styrene epoxidation reaction, which needs to be carried out under high pressure, and the reaction conditions are harsh. Patent CN201811202423.6 discloses a catalyst for styrene epoxidation reaction, which has high conversion rate of styrene and high yield of epoxystyrene, but the mass ratio of hydrogen peroxide to styrene is too large. SUMMARY

[0005] The present application overcomes the above shortcomings, and a heteropoly acid catalyst with metal oxide and graphene as carriers is prepared to complete the epoxidation reaction of styrene at normal pressure, and the conversion rate of styrene and the selectivity of epoxystyrene are high, and the amount of styrene is less. The specific scheme is as follows:

[0006] The multi-phase catalytic oxidation of styrene process is adopted, styrene is used as raw material, 30% hydrogen peroxide is used as oxidant, one of 1, 2-dichloroethane, dichloromethane, DMF and acetonitrile is used as solvent, the multi-acid with graphene and metal oxide as carrier is used as catalyst, and the mixed phosphate is used as additive, and the epoxystyrene can be obtained by reaction at normal pressure, and the catalyst can be recycled after the reaction is completed. The reaction process is simple, the amount of styrene is less, and the product is easy to separate.

[0007] The amount of catalyst is 0.01-0.1 times of the mass of hydrogen peroxide.

[0008] The mass of the mixed phosphate additive is 0.005-0.01 times of the mass of the catalyst.

[0009] The mass ratio of hydrogen peroxide to styrene is 1.09-2.18:1 (molar ratio is 1-2:1).

[0010] The mass ratio of solvent to styrene is 2-5:1

[0011] The reaction temperature is controlled at 30-80℃, and the reaction time is controlled at 3-9h.

[0012] The mass concentration of hydrogen peroxide is 30%.

[0013] The conversion rate of styrene is greater than 95%, the yield of epoxystyrene is greater than 95%, the conversion rate of styrene is greater than 90% after the catalyst is recycled, and the yield of epoxystyrene is greater than 95%.

[0014] After the reaction is completed, the catalyst is recovered by suction filtration or centrifugation method and reused.

[0015] The process is simple, the ratio of raw material to oxidant is low, the production cost is effectively reduced, the energy consumption is low, the environment is friendly, the catalyst is easy to recover, and the product is easy to separate and purify.

[0016] The reaction method is simple, the cost is low, the reaction can be carried out at normal pressure, the catalyst has good catalytic activity, the service life is long, the recovery is easy and the recovery rate is high, the energy consumption is low, the environment is friendly, and the reaction yield is as high as 90% or more. DETAILED DESCRIPTION

[0017] The present application will be further described in detail by the following examples, but the present application is not limited to this scheme

[0018] Example 1

[0019] Take 50g graphite powder, use Hummers method (reference [1] Hummers WS, Offeman RE. Preparation of graphitic oxide [J]. J Am Chem Soc, 1958, 25 (80): 1334-1339. The following examples are the same) to make graphite oxide A, take 29.1g of cobalt nitrate hexahydrate, 16.9g of manganese sulfate monohydrate and 5.12g of magnesium nitrate hexahydrate dissolved in 200mL of 5% mass concentration dilute nitric acid solution, stirring and dissolving, stirring at 50℃ for 12h, to get solution B. Slowly add graphite oxide A to solution B, stir for 5h, to get mixed solution C. Spray drying at 280℃, get catalyst precursor, then reduce the graphite oxide by low temperature plasma discharge method (reference [2] D.C. Wei, Y.Q. Liu, Y. Wang, H.L. Zhang, L.P. Huang and G. Yu. Synthesis of N-Doped Graphene by Chemical Vapor Deposition and Its Electrical Properties [J]. Nano Lett. 2009, 9: 1752-1758. The following examples are the same). Put the catalyst into the atmosphere furnace, calcine at 500℃ for 4h to get catalyst precursor D. Dissolve 10g phosphotungstic acid in 200mL water to form solution E, immerse precursor D in solution E for 5h, filter and dry to get catalyst A, its composition is CoMn1Mg 0.2 O 2.2 / GS-PW12

[0020] Example 2

[0021] Take 60g graphite powder, use Hummers method to make graphite oxide A, take 29.1g of cobalt nitrate hexahydrate, 8.45g of manganese sulfate monohydrate and 10.24g of magnesium nitrate hexahydrate dissolved in 200mL of 8% mass concentration dilute nitric acid solution, stirring and dissolving, stirring at 60℃ for 20h, to get solution B. Slowly add A to B, stir for 8h, to get mixed solution C. Spray drying at 250℃, get catalyst precursor, then reduce the graphite oxide by low temperature plasma discharge method. Put the catalyst into the atmosphere furnace, calcine at 600℃ for 5h to get catalyst precursor D. Dissolve 7g phosphotungstic acid in 200mL water to form solution E, immerse D in E for 8h, filter and dry to get catalyst B, its composition is CoMn 0.5 Mg 0.11 O1.61 / GS-PW12

[0022] Example 3

[0023] Take 60 g of graphite powder, use Hummers method to make graphite oxide A, take 58.2 g of cobalt nitrate hexahydrate, 50.7 g of manganese sulfate monohydrate and 25.6 g of magnesium nitrate hexahydrate, dissolve in 400 mL of 10% mass concentration dilute nitric acid solution, stir to dissolve, stir at 80℃ for 15 h, get solution B. Slowly add A to B, stir for 7 h, get mixed solution C. Spray drying at 300℃, get catalyst precursor, then reduce the graphite oxide by low temperature plasma discharge method. Put the catalyst into the atmosphere furnace, calcine at 550℃ for 4 h to get catalyst precursor D. Dissolve 7 g of phosphotungstic acid in 200 mL of water to form solution E, immerse D in E for 10 h, filter, dry to get catalyst C, the composition is CoMn 1.5 Mg 0.5 O3 / GS-PW12

[0024] Example 4

[0025] In a 250 mL three-necked flask, add DMF 70 g, 0.3 g of catalyst (catalyst prepared in examples 1-3 respectively), 0.15 g of auxiliary mixed phosphate (molar ratio of disodium hydrogen phosphate and sodium dihydrogen phosphate = 1:1) and 27 g of styrene (analytical pure), drop 30 g of 30% mass fraction H2O2 with constant pressure dropping funnel, react at 30℃ for 9 h, after the reaction liquid is cooled to room temperature, centrifuge to recover the catalyst, the liquid is layered in a separatory funnel, and the pure product is obtained by vacuum distillation, and quantified by gas chromatography.

[0026] Catalyst Styrene conversion (%) Epoxystyrene selectivity (%) Example 1 >99 95.3 Example 2 >99 96.6 Example 3 >99 95.2

[0027] Example 5

[0028] In a 250 mL three-necked flask, add DMF 140 g, 0.65 g of catalyst (catalyst prepared in examples 1-3 respectively), 0.35 g of auxiliary mixed phosphate (molar ratio of disodium hydrogen phosphate and sodium dihydrogen phosphate = 1:1) and 33 g of styrene (analytical pure), drop 40 g of 30% mass fraction H2O2 with constant pressure dropping funnel, react at 50℃ for 5 h, after the reaction liquid is cooled to room temperature, centrifuge to recover the catalyst, the liquid is layered in a separatory funnel, and the pure product is obtained by vacuum distillation, and quantified by gas chromatography.

[0029] Catalyst Styrene conversion (%) Epoxystyrene selectivity (%) Example 1 >98 97.0 Example 2 >99 98.4 Example 3 >99 97.7

[0030] Example 6

[0031] In a 250 mL three-necked flask, 1,2-dichloroethane 150 g, 0.6 g of catalyst (catalyst prepared in Examples 1-3, respectively), 0.3 g of auxiliary mixed phosphate salt (molar ratio of sodium hydrogen phosphate and sodium dihydrogen phosphate = 1:1) and 33 g of styrene (analytical pure) were added, and 40 g of H2O2 having a mass percentage of 30% was added dropwise using a constant pressure dropping funnel, and the reaction was performed at 50°C for 4 h. After the reaction solution was cooled to room temperature, the catalyst was recovered by centrifugation, the liquid was separated in a separatory funnel, and the pure product was obtained by distillation under reduced pressure. The amount of the product was quantified by gas chromatography.

[0032] Catalyst Styrene conversion (%) Epoxystyrene selectivity (%) Example 1 >99.9 99.5 Example 2 >99 98.5 Example 3 >99 98.2

[0033] Example 7

[0034] In a 250 mL three-necked flask, 1,2-dichloroethane 100 g, 0.7 g of catalyst (catalyst prepared in Examples 1-3, respectively), 0.25 g of auxiliary mixed phosphate salt (molar ratio of sodium hydrogen phosphate and sodium dihydrogen phosphate = 1:1) and 30 g of styrene (analytical pure) were added, and 40 g of H2O2 having a mass percentage of 30% was added dropwise using a constant pressure dropping funnel, and the reaction was performed at 40°C for 8 h. After the reaction solution was cooled to room temperature, the catalyst was recovered by centrifugation, the liquid was separated in a separatory funnel, and the pure product was obtained by distillation under reduced pressure. The amount of the product was quantified by gas chromatography.

[0035] Catalyst Styrene conversion (%) Epoxystyrene selectivity (%) Example 1 >99 95.3 Example 2 >99 98.1 Example 3 >99 98.1

[0036] Example 8

[0037] In a 250 mL three-necked flask, 1,2-dichloroethane 120 g, 0.7 g of catalyst (catalyst prepared in Examples 1-3, respectively), 0.26 g of auxiliary mixed phosphate salt (molar ratio of sodium hydrogen phosphate and sodium dihydrogen phosphate = 1:1) and 30 g of styrene (analytical pure) were added, and 40 g of H2O2 having a mass percentage of 30% was added dropwise using a constant pressure dropping funnel, and the reaction was performed at 55°C for 5 h. After the reaction solution was cooled to room temperature, the catalyst was recovered by centrifugation, the liquid was separated in a separatory funnel, and the pure product was obtained by distillation under reduced pressure. The amount of the product was quantified by gas chromatography.

[0038] Catalyst Styrene conversion (%) Epoxystyrene selectivity (%) Example 1 >97 95.7 Example 2 >99 98.7 Example 3 100 99.5

[0039] Example 9

[0040] In a 250 mL three-necked flask, dichloromethane 50 g, 0.7 g of catalyst (catalyst prepared in Examples 1-3, respectively), 0.26 g of mixed phosphate assistant (molar ratio of sodium hydrogen phosphate and sodium dihydrogen phosphate = 1:1) and 20 g of styrene (analytical pure) were added, and 40 g of H2O2 (30% by mass) was added dropwise using a constant pressure dropping funnel, and the reaction was carried out at 60°C for 4 h. After the reaction solution was cooled to room temperature, the catalyst was recovered by centrifugation, the liquid was separated in a separating funnel, and the pure product was obtained by distillation under reduced pressure. The amount of the product was quantified by gas chromatography.

[0041] Catalyst Styrene conversion (%) Epoxystyrene selectivity (%) Example 1 >99 98.9 Example 2 >98 97.9 Example 3 >99 96.8

[0042] Example 10

[0043] In a 250 mL three-necked flask, dichloromethane 50 g, 1.2 g of catalyst (catalyst prepared in Examples 1-3, respectively), 0.3 g of mixed phosphate assistant (molar ratio of sodium hydrogen phosphate and sodium dihydrogen phosphate = 1:1) and 25 g of styrene (analytical pure) were added, and 40 g of H2O2 (30% by mass) was added dropwise using a constant pressure dropping funnel, and the reaction was carried out at 65°C for 3 h. After the reaction solution was cooled to room temperature, the catalyst was recovered by centrifugation, the liquid was separated in a separating funnel, and the pure product was obtained by distillation under reduced pressure. The amount of the product was quantified by gas chromatography.

[0044] Catalyst Styrene conversion (%) Epoxystyrene selectivity (%) Example 1 100 95.9 Example 2 >99 97.4 Example 3 >99 99.0

[0045] Example 11

[0046] The catalyst in Example 7 was recovered, and in a 250 mL three-necked flask, dichloromethane 50 g, 5% of the catalyst (catalyst prepared in Examples 1-3, respectively) was added, 0.3 g of mixed phosphate assistant (molar ratio of sodium hydrogen phosphate and sodium dihydrogen phosphate = 1:1) and 25 g of styrene (analytical pure) were added, and 40 g of H2O2 (30% by mass) was added dropwise using a constant pressure dropping funnel, and the reaction was carried out at 65°C for 3 h. After the reaction solution was cooled to room temperature, the catalyst was recovered by centrifugation, the liquid was separated in a separating funnel, and the pure product was obtained by distillation under reduced pressure. The amount of the product was quantified by gas chromatography.

[0047] Catalyst Styrene conversion (%) Epoxystyrene selectivity (%) Example 1 >99 97.9 Example 2 >99 98.7 Example 3 >99 96.6

[0048] Example 12

[0049] The catalyst in Example 8 was recovered and recycled. In a 250 mL three-necked flask, 50 g of dichloromethane was added, 5% catalyst (the catalyst prepared in Examples 1-3, respectively) was added, 0.3 g of auxiliary mixed phosphate (molar ratio of disodium hydrogen phosphate and sodium dihydrogen phosphate = 1:1) and 25 g of styrene (analytical pure) were added, 240 g of 30% mass fraction H2O was added dropwise by constant pressure dropping funnel, and the reaction was carried out at 65°C for 3 h. After the reaction liquid was cooled to room temperature, the catalyst was recovered by centrifugation, the liquid was separated in a separatory funnel, and the pure product was obtained by distillation under reduced pressure. After 5 cycles, the product was quantified by gas chromatography.

[0050] Catalyst Styrene conversion (%) Epoxystyrene selectivity (%) Example 1 >95 96.9 Example 2 >90 97.3 Example 3 Catalyst Styrene conversion (%) Epoxystyrene selectivity (%) Example 1 Example 2 Example 3 Catalyst Styrene conversion (%) Epoxystyrene selectivity (%) Example 1 Example 2 Example 3 >90 96.8

[0051] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A supported heteropolyacid catalyst, characterized in that The catalyst includes the following elements: CoMn a Mg b O c / GS-PW12: a and b are the molar specific gravity of metal Mn and Mg, respectively; The value range of a is 0.5-2; The value range of b is 0.1-0.8; c is the ratio of oxygen atoms required to satisfy the metal oxidation state; The weight content of GS graphene in the catalyst is 40-70%, and the mass content of PW12 is 5-10%.

2. The catalyst according to claim 1, characterized in that The value range of b is 0.2-0.

8.

3. A method for synthesizing the catalyst according to claim 1, characterized in that: a. Graphite flakes are prepared into graphite oxide A using the Hummers method; b. Disperse or dissolve the desired metal precursor salt in a dilute nitric acid aqueous solution with a mass concentration of 1-10%, stir evenly, and stir at 40-90 ° C for 10-24h to obtain solution B; c. Add solution A to solution B and stir for 2-12 hours to obtain mixed solution C; d. spray drying at 250-300 ° C to obtain a catalyst precursor; e. using plasma discharge to reduce graphite oxide in the precursor to graphene; f. The catalyst was placed in an atmosphere furnace and calcined at 400-900 ° C for 3-10 h to obtain a catalyst precursor D; g. The phosphotungstic acid PW12 was dissolved in water to form a solution E; h. Immerse catalyst precursor D in solution E for 3-12 hours, filter, and dry to obtain the catalyst.

4. A method for preparing styrene oxide using the supported heteropolyacid catalyst according to claim 1, comprising: Styrene is directly oxidized to styrene oxide in the presence of a catalyst and a mixed phosphate auxiliary agent, using one or more organic solvents selected from 1,2-dichloroethane, dichloromethane, DMF, and acetonitrile as solvents and hydrogen peroxide as an oxidant. After the reaction is completed, the reaction liquid is cooled, and the solid catalyst in the reaction liquid is recovered by filtration or centrifugation and recycled.

5. The method for preparing styrene oxide according to claim 4, wherein: The amount of catalyst used is 0.01~0.1 times the mass of hydrogen peroxide.

6. The method for preparing styrene oxide according to claim 4, wherein: The mass of the additive mixed phosphate is 0.005~0.01 times the mass of the catalyst; The mixed phosphate is disodium hydrogen phosphate and sodium dihydrogen phosphate, and the molar ratio thereof is 1:

1.

7. The method for preparing styrene oxide according to claim 4, wherein: The molar ratio of hydrogen peroxide to styrene is 1-2:1, and the mass concentration of hydrogen peroxide is 25-35%.

8. The method for preparing styrene oxide according to claim 4, wherein: The mass ratio of solvent to styrene is 2-5:

1.

9. The method for preparing styrene oxide according to claim 4, wherein: The reaction temperature is controlled at 30-80°C, and the reaction time is controlled at 3-9 h.

10. The method for preparing styrene oxide according to claim 4, wherein: After the reaction is completed, the solid catalyst in the reaction liquid is recovered by filtration or centrifugation and then recycled; The conversion rate of styrene is greater than 95%, the yield of styrene oxide is greater than 95%, the conversion rate of styrene recycled after catalyst recovery is greater than 90%, and the yield of styrene oxide is greater than 95%.