A method for preparing epichlorohydrin and its catalyst

Abstract

This invention proposes a method for preparing epichlorohydrin and its catalyst, belonging to the field of organic chemistry. Using hydrogen peroxide and allyl chloride as raw materials, epichlorohydrin is produced through a reaction under the action of a catalyst. The catalyst is a layered metal oxide / Al₂O₃ / SiO₂ microsphere supported on K and Mo, and its surface is modified with phytic acid and β-cyclodextrin. The preparation method of this invention is simple, operates under mild conditions, and can occur under normal pressure. The catalyst has high activity, can be used for multiple catalytic reactions, and exhibits high reactant conversion with few byproducts, achieving a conversion rate of over 90%.

Description

Technical Field

[0001] This invention relates to the field of organic chemistry, specifically to a method for preparing epichlorohydrin and its catalyst. Background Technology

[0002] Epichlorohydrin, also known as epichlorohydrin, with the chemical name 3-chloro-1,2-epoxypropane, is an important organic chemical raw material and synthetic intermediate. Among epoxy compounds, epichlorohydrin ranks third in production volume, after ethylene oxide and propylene oxide. Epichlorohydrin can be used as a solvent for cellulose esters, resins, and cellulose ethers, and is also a raw material for the production of surfactants, pharmaceuticals, pesticides, coatings, adhesives, ion exchange resins, plasticizers, glycerol derivatives, and glycidyl derivatives. Various epoxy resins prepared from epichlorohydrin and bisphenol A possess strong adhesion, low shrinkage, chemical resistance, and good stability, and are widely used in coatings, adhesives, reinforcing materials, and casting materials. Chlorohydrin rubber, produced from epichlorohydrin, is a new type of rubber. It does not easily swell in common solvents and exhibits significant flexibility (superior to nitrile rubber, chloroprene rubber, and butyl rubber) at low temperatures without plasticizers.

[0003] As an important organic chemical raw material and fine chemical product, epichlorohydrin is widely used in chemical, light industry, pharmaceutical, and electronics industries. Currently, there are three main methods for producing epichlorohydrin: the high-temperature chlorination process using propylene as raw material, the propylene acetate process, and the glycerol process using glycerol as raw material. The high-temperature chlorination process, first successfully developed and industrialized by Shell in the United States in 1948, is the classic method for producing epichlorohydrin. Currently, over 90% of the world's epichlorohydrin is produced using this method. However, this process has drawbacks: the chlorine gas from the raw material severely corrodes equipment; it requires high purity propylene and high-quality reactor materials; it consumes a large amount of energy and chlorine; it produces many byproducts; the product yield is low (approximately 70%); and it generates a large volume of wastewater containing calcium chloride and organic chlorides, resulting in high treatment costs, easy coking, and a short decoking cycle. To address these shortcomings, new methods for preparing epichlorohydrin have been developed.

[0004] Chinese invention patent CN102453006B discloses a method for the direct epoxidation of allyl chloride to epichlorohydrin. In this method, in the presence of a quaternary ammonium phosphate additive, an excess of allyl chloride relative to the oxidant reacts with hydrogen peroxide as the oxidant under reflux conditions in the presence of a quaternary ammonium phosphate catalyst (phosphotungstic heteropoly acid quaternary ammonium salt) to directly generate epichlorohydrin. The catalyst is dissolved in the reaction solution during the reaction and precipitates after the reaction. However, there are problems with incomplete dissolution and precipitation of the catalyst, which directly affects the catalyst activity and recovery rate.

[0005] Chinese invention patent CN101747297B discloses a method for the continuous production of epichlorohydrin. This method includes introducing 3-chloropropene, hydrogen peroxide, and a solvent into multiple fixed-bed reactors containing titanium-silicon molecular sieve catalysts, causing an epoxidation reaction between 3-chloropropene and hydrogen peroxide. The epoxidation reaction is then stopped in at least one fixed-bed reactor to regenerate the catalyst. During catalyst regeneration in any one reactor, an epoxidation reaction occurs in at least one of the other reactors. However, this method uses hydrogen peroxide as the oxidant. Since hydrogen peroxide decomposes at high temperatures, the utilization rate of the raw materials decreases, and the decomposition of hydrogen peroxide produces oxygen, which poses an explosion hazard when mixed with chloropropene. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing epichlorohydrin and its catalyst. The preparation method is simple, the conditions are mild, the reaction can occur under normal pressure, the catalyst has high activity, can be catalyzed multiple times, the reactant conversion rate is high, the by-products are few, and the conversion rate reaches more than 90%.

[0007] The technical solution of this invention is implemented as follows:

[0008] This invention provides a method for preparing epichlorohydrin, using hydrogen peroxide and allyl chloride as raw materials, reacting them under the action of a catalyst to generate epichlorohydrin. The catalyst is a catalyst supported on layered metal oxide / Al2O3 / SiO2 microspheres, loaded with K and Mo, and modified with phytic acid and β-cyclodextrin on its surface.

[0009] As a further improvement of the present invention, the mass ratio of hydrogen peroxide to allyl chloride is 0.02-0.2:1.

[0010] As a further improvement of the present invention, the reaction temperature is 70-80°C and the reaction time is 1-5 hours.

[0011] As a further improvement of the present invention, the catalyst is prepared by the following method:

[0012] S1. Preparation of porous Al2O3 / SiO2 microspheres: Alkyl orthosilicate and aluminum isopropoxide were dissolved in ethanol, a pore-forming agent, ammonia and water were added, the mixture was stirred and reacted, centrifuged, washed, dried and calcined to obtain porous Al2O3 / SiO2 microspheres.

[0013] S2. Deposition of layered metal oxides: Zinc nitrate, iron nitrate, and nickel nitrate were dissolved in water, an alkaline solution was added dropwise, porous Al2O3 / SiO2 microspheres were added, the mixture was heated to crystallize, filtered, washed, dried, and calcined to obtain layered metal oxide / Al2O3 / SiO2 microspheres.

[0014] S3. Impregnation: Potassium carbonate and ammonium molybdate are dissolved in water to prepare an impregnation solution. Layered metal oxide / Al2O3 / SiO2 microspheres are added, and the solvent is evaporated to obtain a mixture.

[0015] S4. Calcination: The mixture is calcined to obtain K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres;

[0016] S5. Catalyst preparation: K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres, phytic acid, β-cyclodextrin, and potassium dihydrogen phosphate were added to water, subjected to hydrothermal reaction, filtered, washed, and dried to obtain the catalyst.

[0017] As a further improvement of the present invention, the alkyl orthosilicate in step S1 is methyl orthosilicate or ethyl orthosilicate, the mass ratio of the alkyl orthosilicate, aluminum isopropoxide, pore-forming agent, ammonia and water is 12-15:7-10:2-3:5-7:10-12, the stirring reaction time is 7-10 h, the calcination temperature is 400-500 °C and the time is 2-4 h, and the pore-forming agent is hexadecyltrimethylammonium bromide.

[0018] As a further improvement of the present invention, the mass ratio of zinc nitrate, iron nitrate, nickel nitrate, and Al2O3 / SiO2 microspheres in step S2 is 3-4:5-7:1-2:10; the pH value of the solution is adjusted to 7-7.5 by adding alkaline solution; the temperature for heating and crystallization is 85-95℃ and the time is 20-40 min; the temperature for calcination is 600-700℃ and the time is 2-4 h; and the alkaline solution is a 0.5-1 mol / L NaOH or KOH solution.

[0019] As a further improvement of the present invention, the mass ratio of potassium carbonate, ammonium molybdate and layered metal oxide / Al2O3 / SiO2 microspheres in step S3 is 3-5:7-10:13-17.

[0020] As a further improvement of the present invention, the roasting temperature in step S4 is 600-800℃ and the time is 1-3h.

[0021] As a further improvement of the present invention, the mass ratio of K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres, phytic acid, β-cyclodextrin and potassium dihydrogen phosphate in step S5 is 10:3-5:5-7:0.2-0.5, the hydrothermal reaction temperature is 130-160℃, and the time is 8-10h.

[0022] This invention further protects the above-mentioned catalyst, the preparation method of which includes the following steps:

[0023] S1. Preparation of porous Al2O3 / SiO2 microspheres: 12-15 parts by weight of alkyl orthosilicate and 7-10 parts by weight of aluminum isopropoxide were dissolved in ethanol, and 2-3 parts by weight of pore-forming agent, 5-7 parts by weight of ammonia and 10-12 parts by weight of water were added. The mixture was stirred and reacted for 7-10 h, centrifuged, washed, dried and calcined at 400-500℃ for 2-4 h to obtain porous Al2O3 / SiO2 microspheres.

[0024] S2. Deposition of layered metal oxides: Dissolve 3-4 parts by weight of zinc nitrate, 5-7 parts by weight of iron nitrate, and 1-2 parts by weight of nickel nitrate in water. Adjust the pH of the solution to 7-7.5 by adding 0.5-1 mol / L NaOH or KOH solution. Add 10 parts by weight of Al2O3 / SiO2 microspheres, heat to 85-95℃, crystallize for 20-40 min, filter, wash, dry, and calcine at 600-700℃ for 2-4 h to obtain layered metal oxide / Al2O3 / SiO2 microspheres.

[0025] S3. Impregnation: Dissolve 3-5 parts by weight of potassium carbonate and 7-10 parts by weight of ammonium molybdate in water to prepare an impregnation solution, add 13-17 parts by weight of layered metal oxide / Al2O3 / SiO2 microspheres, evaporate the solvent to obtain a mixture;

[0026] S4. Calcination: The mixture is calcined at 600-800℃ for 1-3 hours to obtain K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres;

[0027] S5. Preparation of catalyst: 10 parts by weight of K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres, 3-5 parts by weight of phytic acid, 5-7 parts by weight of β-cyclodextrin, and 0.2-0.5 parts by weight of potassium dihydrogen phosphate were added to water and hydrothermally reacted at 130-160℃ for 8-10 h. The mixture was then filtered, washed, and dried to obtain the catalyst.

[0028] The present invention has the following beneficial effects:

[0029] Molybdenum (Mo) is a group VI transition metal with incomplete N and O electron shell distribution, making it easier for it to donate and accept electrons. Therefore, Mo has multiple variable valences, resulting in excellent catalytic performance. In this invention, Mo metal exhibits good catalytic activity, and the addition of K has a synergistic catalytic effect.

[0030] This invention uses porous Al2O3 / SiO2 microspheres as one of the supports. When γ-Al2O3 is used alone as a support, it easily reacts with the precursor, affecting the catalytic activity. Therefore, by using a composite oxide as a support, the prepared Al2O3 / SiO2 microspheres can maintain the structural advantage of the large specific surface area of ​​γ-Al2O3 while inhibiting the contact between the precursor and γ-Al2O3, thus better exerting catalytic activity. Furthermore, the surface deposition of ZnNiFe layered metal oxides increases the specific surface area of ​​the catalyst, which helps to improve the loading of K and Mo. On the other hand, the metals Zn, Ni, and Fe have a good promoting effect on the catalytic effect, improving the conversion rate of the reaction.

[0031] This invention further involves surface loading of phytic acid and β-cyclodextrin, and the synthetic route is as follows:

[0032]

[0033] The cavities of phytic acid and β-cyclodextrin facilitate the contact between hydrogen peroxide and allyl chloride with the catalyst, promoting their in-situ reaction, improving catalytic activity, and increasing the reaction conversion rate. This allows the present invention to achieve good conversion efficiency at lower temperatures and at room temperature, with a conversion rate of over 90%.

[0034] The preparation method of this invention is simple, the conditions are mild, the reaction can occur under normal pressure, the catalyst has high activity and can be catalyzed multiple times, the reactant conversion rate is high, the by-products are few, and the conversion rate reaches more than 90%. Detailed Implementation

[0035] 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.

[0036] Example 1

[0037] This embodiment provides a catalyst, the preparation method of which includes the following steps:

[0038] S1. Preparation of porous Al2O3 / SiO2 microspheres: 12g of methyl orthosilicate and 7g of aluminum isopropoxide were dissolved in 100mL of ethanol, 2g of cetyltrimethylammonium bromide, 5g of ammonia and 10g of water were added, the mixture was stirred and reacted for 7h, centrifuged, washed, dried and calcined at 400℃ for 2h to obtain porous Al2O3 / SiO2 microspheres;

[0039] S2. Deposition of layered metal oxides: Dissolve 3g zinc nitrate, 5g iron nitrate, and 1g nickel nitrate in 200mL of water, add 0.5mol / L NaOH solution to adjust the pH of the solution to 7, add 10g porous Al2O3 / SiO2 microspheres, heat to 85℃, crystallize for 20min, filter, wash, dry, and calcine at 600℃ for 2h to obtain layered metal oxide / Al2O3 / SiO2 microspheres;

[0040] S3. Impregnation: Dissolve 3g of potassium carbonate and 7g of ammonium molybdate in 150mL of water to prepare an impregnation solution, add 13g of layered metal oxide / Al2O3 / SiO2 microspheres, evaporate the solvent to obtain a mixture;

[0041] S4. Calcination: The mixture was calcined at 600℃ for 1 hour to obtain K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres;

[0042] S5. Preparation of catalyst: 10g K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres, 3g phytic acid, 5g β-cyclodextrin and 0.2g potassium dihydrogen phosphate were added to 200mL of water and hydrothermally reacted at 130℃ for 8h. After filtration, washing and drying, the catalyst was obtained.

[0043] Example 2

[0044] This embodiment provides a catalyst, the preparation method of which includes the following steps:

[0045] S1. Preparation of porous Al2O3 / SiO2 microspheres: 15g of tetraethyl orthosilicate and 10g of aluminum isopropoxide were dissolved in 100mL of ethanol, 3g of cetyltrimethylammonium bromide, 7g of ammonia and 12g of water were added, the mixture was stirred and reacted for 10h, centrifuged, washed, dried and calcined at 500℃ for 4h to obtain porous Al2O3 / SiO2 microspheres;

[0046] S2. Deposition of layered metal oxides: 4g zinc nitrate, 7g iron nitrate and 2g nickel nitrate were dissolved in 200mL of water, and 1mol / L KOH solution was added dropwise to adjust the pH of the solution to 7.5. 10g of porous Al2O3 / SiO2 microspheres were added, heated to 95℃, crystallized for 40min, filtered, washed, dried and calcined at 700℃ for 4h to obtain layered metal oxide / Al2O3 / SiO2 microspheres;

[0047] S3. Impregnation: Dissolve 5g of potassium carbonate and 10g of ammonium molybdate in 150mL of water to prepare an impregnation solution, add 17g of layered metal oxide / Al2O3 / SiO2 microspheres, evaporate the solvent, and obtain a mixture;

[0048] S4. Calcination: The mixture was calcined at 800℃ for 3 hours to obtain K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres;

[0049] S5. Preparation of catalyst: 10g K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres, 5g phytic acid, 7g β-cyclodextrin and 0.5g potassium dihydrogen phosphate were added to 200mL of water and hydrothermally reacted at 160℃ for 10h. After filtration, washing and drying, the catalyst was obtained.

[0050] Example 3

[0051] This embodiment provides a catalyst, the preparation method of which includes the following steps:

[0052] S1. Preparation of porous Al2O3 / SiO2 microspheres: 13g of tetraethyl orthosilicate and 8g of aluminum isopropoxide were dissolved in 100mL of ethanol, and 2.5g of cetyltrimethylammonium bromide, 6g of ammonia and 11g of water were added. The mixture was stirred and reacted for 8h, centrifuged, washed, dried and calcined at 450℃ for 3h to obtain porous Al2O3 / SiO2 microspheres.

[0053] S2. Deposition of layered metal oxides: Dissolve 3.5g zinc nitrate, 6g iron nitrate, and 1.5g nickel nitrate in 200mL of water, add 0.7mol / L KOH solution to adjust the pH of the solution to 7.5, add 10g porous Al2O3 / SiO2 microspheres, heat to 90℃, crystallize for 30min, filter, wash, dry, and calcine at 650℃ for 3h to obtain layered metal oxide / Al2O3 / SiO2 microspheres;

[0054] S3. Impregnation: Dissolve 4g of potassium carbonate and 8g of ammonium molybdate in 150mL of water to prepare an impregnation solution, add 15g of layered metal oxide / Al2O3 / SiO2 microspheres, evaporate the solvent to obtain a mixture;

[0055] S4. Calcination: The mixture was calcined at 650℃ for 2 hours to obtain K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres;

[0056] S5. Preparation of catalyst: 10g K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres, 4g phytic acid, 6g β-cyclodextrin and 0.3g potassium dihydrogen phosphate were added to 200mL of water and hydrothermally reacted at 145℃ for 9h. After filtration, washing and drying, the catalyst was obtained.

[0057] Comparative Example 1

[0058] The difference from Example 3 is that tetraethyl orthosilicate was not added in step S1.

[0059] Specifically as follows:

[0060] S1. Preparation of porous Al2O3 microspheres: 21g of aluminum isopropoxide was dissolved in 100mL of ethanol, and 2.5g of cetyltrimethylammonium bromide, 6g of ammonia and 11g of water were added. The mixture was stirred and reacted for 8h, centrifuged, washed, dried and calcined at 450℃ for 3h to obtain porous Al2O3 microspheres.

[0061] Comparative Example 2

[0062] The difference from Example 3 is that cetyltrimethylammonium bromide was not added in step S1.

[0063] Specifically as follows:

[0064] Preparation of Al2O3 / SiO2 microspheres: 13g of tetraethyl orthosilicate and 8g of aluminum isopropoxide were dissolved in 100mL of ethanol, 6g of ammonia and 11g of water were added, the mixture was stirred for 8h, centrifuged, washed, dried and calcined at 450℃ for 3h to obtain Al2O3 / SiO2 microspheres.

[0065] Comparative Example 3

[0066] The difference from Example 3 is that step S2 was not performed.

[0067] Specifically as follows:

[0068] S1. Preparation of porous Al2O3 / SiO2 microspheres: 13g of tetraethyl orthosilicate and 8g of aluminum isopropoxide were dissolved in 100mL of ethanol, and 2.5g of cetyltrimethylammonium bromide, 6g of ammonia and 11g of water were added. The mixture was stirred and reacted for 8h, centrifuged, washed, dried and calcined at 450℃ for 3h to obtain porous Al2O3 / SiO2 microspheres.

[0069] S2. Impregnation: Dissolve 4g of potassium carbonate and 8g of ammonium molybdate in 150mL of water to prepare an impregnation solution, add 15g of porous Al2O3 / SiO2 microspheres, evaporate the solvent to obtain a mixture;

[0070] S3. Calcination: The mixture was calcined at 650℃ for 2 hours to obtain K / Mo-Al2O3 / SiO2 microspheres;

[0071] S4. Preparation of catalyst: 10g K / Mo-Al2O3 / SiO2 microspheres, 4g phytic acid, 6g β-cyclodextrin and 0.3g potassium dihydrogen phosphate were added to 200mL of water and hydrothermally reacted at 145℃ for 9h. After filtration, washing and drying, the catalyst was obtained.

[0072] Comparative Example 4

[0073] The difference from Example 3 is that potassium carbonate was not added in step S3.

[0074] Specifically as follows:

[0075] S3. Impregnation: Dissolve 12g of ammonium molybdate in 150mL of water to prepare an impregnation solution, add 15g of layered metal oxide / Al2O3 / SiO2 microspheres, evaporate the solvent, and obtain a mixture.

[0076] Comparative Example 5

[0077] The difference from Example 3 is that step S5 was not performed.

[0078] Specifically as follows:

[0079] S1. Preparation of porous Al2O3 / SiO2 microspheres: 13g of tetraethyl orthosilicate and 8g of aluminum isopropoxide were dissolved in 100mL of ethanol, and 2.5g of cetyltrimethylammonium bromide, 6g of ammonia and 11g of water were added. The mixture was stirred and reacted for 8h, centrifuged, washed, dried and calcined at 450℃ for 3h to obtain porous Al2O3 / SiO2 microspheres.

[0080] S2. Deposition of layered metal oxides: Dissolve 3.5g zinc nitrate, 6g iron nitrate, and 1.5g nickel nitrate in 200mL of water, add 0.7mol / L KOH solution to adjust the pH of the solution to 7.5, add 10g porous Al2O3 / SiO2 microspheres, heat to 90℃, crystallize for 30min, filter, wash, dry, and calcine at 650℃ for 3h to obtain layered metal oxide / Al2O3 / SiO2 microspheres;

[0081] S3. Impregnation: Dissolve 4g of potassium carbonate and 8g of ammonium molybdate in 150mL of water to prepare an impregnation solution, add 15g of layered metal oxide / Al2O3 / SiO2 microspheres, evaporate the solvent to obtain a mixture;

[0082] S4. Calcination: The mixture is calcined at 650℃ for 2 hours to obtain K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres, which are the catalyst.

[0083] Test Example 1

[0084] The specific surface area and total pore volume of the catalysts for preparing diethyltoluenediamine prepared in Examples 1-3 and Comparative Examples 1-5 were determined using a multi-station high-throughput gas adsorption analyzer.

[0085] The results are shown in Table 1.

[0086] Table 1

[0087] Group <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[Total pore volume (cm 3 / g)]]> Example 1 844.1 0.711 Example 2 845.9 0.712 Example 3 847.8 0.715 Comparative Example 1 821.5 0.689 Comparative Example 2 774.5 0.612 Comparative Example 3 721.9 0.578 Comparative Example 4 831.2 0.704 Comparative Example 5 815.7 0.694

[0088] As can be seen from the table above, the catalysts prepared in Examples 1-3 of this invention have a large specific surface area and total pore volume.

[0089] Example 4

[0090] This embodiment provides a method for preparing epichlorohydrin, using hydrogen peroxide and allyl chloride as raw materials, wherein the mass ratio of hydrogen peroxide to allyl chloride is 0.1:1, and under the action of the catalyst obtained in Example 1, the amount of catalyst added is 5 wt% of allyl chloride, and the reaction is carried out at 70°C for 5 h to generate epichlorohydrin.

[0091] Example 5

[0092] This embodiment provides a method for preparing epichlorohydrin, using hydrogen peroxide and allyl chloride as raw materials, wherein the mass ratio of hydrogen peroxide to allyl chloride is 0.1:1, and under the action of the catalyst obtained in Example 2, the amount of catalyst added is 5 wt% of allyl chloride, and the reaction is carried out at 80°C for 5 h to generate epichlorohydrin.

[0093] Example 6

[0094] This embodiment provides a method for preparing epichlorohydrin, using hydrogen peroxide and allyl chloride as raw materials, wherein the mass ratio of hydrogen peroxide to allyl chloride is 0.1:1, and under the action of the catalyst obtained in Example 3, the amount of catalyst added is 5 wt% of allyl chloride, and the reaction is carried out at 75°C for 5 h to generate epichlorohydrin.

[0095] Comparative Example 6

[0096] The difference from Example 6 is that the catalyst was prepared from Comparative Example 1.

[0097] Comparative Example 7

[0098] The difference from Example 6 is that the catalyst was prepared from Comparative Example 2.

[0099] Comparative Example 8

[0100] The difference from Example 6 is that the catalyst was prepared from Comparative Example 3.

[0101] Comparative Example 9

[0102] The difference from Example 6 is that the catalyst was prepared from Comparative Example 4.

[0103] Comparative Example 10

[0104] The difference from Example 6 is that the catalyst was prepared from Comparative Example 5.

[0105] Test Example 2

[0106] The reactions of Examples 4-6 and Comparative Examples 6-10 were evaluated, and the results are shown in Table 2.

[0107] Table 2

[0108] Group Hydrogen peroxide conversion rate (%) Selectivity of epichlorohydrin (%) Example 4 95.9 99.4 Example 5 96.2 99.5 Example 6 96.7 99.8 Comparative Example 6 91.1 92.8 Comparative Example 7 92.7 94.2 Comparative Example 8 86.5 90.8 Comparative Example 9 89.3 91.4 Comparative Example 10 90.2 88.7

[0109] As can be seen from the table above, the reaction methods in Examples 4-6 of this invention have a high conversion rate of hydrogen peroxide and a high selectivity for epichlorohydrin.

[0110] 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 epichlorohydrin, using hydrogen peroxide and allyl chloride as raw materials, characterized in that, Under the action of a catalyst, epichlorohydrin is generated. The catalyst is a catalyst supported on layered metal oxide / Al2O3 / SiO2 microspheres, loaded with K and Mo, and modified with phytic acid and β-cyclodextrin on the surface. The catalyst is prepared as follows: S1. Preparation of porous Al2O3 / SiO2 microspheres: Alkyl orthosilicate and aluminum isopropoxide were dissolved in ethanol, a pore-forming agent, ammonia and water were added, the mixture was stirred and reacted, centrifuged, washed, dried and calcined to obtain porous Al2O3 / SiO2 microspheres; S2. Deposition of layered metal oxides: Zinc nitrate, iron nitrate, and nickel nitrate were dissolved in water, an alkaline solution was added dropwise, porous Al2O3 / SiO2 microspheres were added, the mixture was heated to crystallize, filtered, washed, dried, and calcined to obtain layered metal oxide / Al2O3 / SiO2 microspheres; S3. Impregnation: Dissolve potassium carbonate and ammonium molybdate in water to prepare an impregnation solution, add layered metal oxide / Al2O3 / SiO2 microspheres, evaporate the solvent to obtain a mixture; S4. Calcination: The mixture is calcined to obtain K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres; S5. Catalyst preparation: K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres, phytic acid, β-cyclodextrin, and potassium dihydrogen phosphate were added to water, subjected to hydrothermal reaction, filtered, washed, and dried to obtain the catalyst.

2. The preparation method according to claim 1, characterized in that, The mass ratio of hydrogen peroxide to allyl chloride is 0.02-0.2:

1.

3. The preparation method according to claim 1, characterized in that, The reaction temperature is 70-80℃, and the reaction time is 1-5 hours.

4. The preparation method according to claim 1, characterized in that, The alkyl orthosilicate mentioned in step S1 is methyl or ethyl orthosilicate. The mass ratio of the alkyl orthosilicate, aluminum isopropoxide, pore-forming agent, ammonia, and water is 12-15:7-10:2-3:5-7:10-12. The stirring reaction time is 7-10 h. The calcination temperature is 400-500 °C and the time is 2-4 h. The pore-forming agent is hexadecyltrimethylammonium bromide.

5. The preparation method according to claim 1, characterized in that, In step S2, the mass ratio of zinc nitrate, iron nitrate, nickel nitrate, and Al2O3 / SiO2 microspheres is 3-4:5-7:1-2:

10. The pH of the solution is adjusted to 7-7.5 by adding alkali solution. The temperature for heating and crystallization is 85-95℃ for 20-40 min. The temperature for calcination is 600-700℃ for 2-4 h. The alkali solution is a 0.5-1 mol / L NaOH or KOH solution.

6. The preparation method according to claim 1, characterized in that, The mass ratio of potassium carbonate, ammonium molybdate, and layered metal oxide / Al2O3 / SiO2 microspheres in step S3 is 3-5:7-10:13-17.

7. The preparation method according to claim 1, characterized in that, The roasting temperature in step S4 is 600-800℃, and the time is 1-3h.

8. The preparation method according to claim 1, characterized in that, In step S5, the mass ratio of K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres, phytic acid, β-cyclodextrin, and potassium dihydrogen phosphate is 10:3-5:5-7:0.2-0.5, and the hydrothermal reaction temperature is 130-160℃ for 8-10 hours.

9. A catalyst used in claim 1, characterized in that, The preparation method includes the following steps: S1. Preparation of porous Al2O3 / SiO2 microspheres: 12-15 parts by weight of alkyl orthosilicate and 7-10 parts by weight of aluminum isopropoxide were dissolved in ethanol, and 2-3 parts by weight of pore-forming agent, 5-7 parts by weight of ammonia and 10-12 parts by weight of water were added. The mixture was stirred and reacted for 7-10 h, centrifuged, washed, dried and calcined at 400-500℃ for 2-4 h to obtain porous Al2O3 / SiO2 microspheres. S2. Deposition of layered metal oxides: Dissolve 3-4 parts by weight of zinc nitrate, 5-7 parts by weight of iron nitrate, and 1-2 parts by weight of nickel nitrate in water, add 0.5-1 mol / L NaOH or KOH solution to adjust the pH of the solution to 7-7.5, add 10 parts by weight of Al2O3 / SiO2 microspheres, heat to 85-95℃, crystallize for 20-40 min, filter, wash, dry, and calcine at 600-700℃ for 2-4 h to obtain layered metal oxide / Al2O3 / SiO2 microspheres; S3. Impregnation: Dissolve 3-5 parts by weight of potassium carbonate and 7-10 parts by weight of ammonium molybdate in water to prepare an impregnation solution, add 13-17 parts by weight of layered metal oxide / Al2O3 / SiO2 microspheres, evaporate the solvent to obtain a mixture; S4. Calcination: The mixture is calcined at 600-800℃ for 1-3 hours to obtain K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres; S5. Preparation of catalyst: 10 parts by weight of K / Mo-layered metal oxide / Al2O3 / SiO2 microspheres, 3-5 parts by weight of phytic acid, 5-7 parts by weight of β-cyclodextrin, and 0.2-0.5 parts by weight of potassium dihydrogen phosphate were added to water and hydrothermally reacted at 130-160℃ for 8-10 h. The mixture was then filtered, washed, and dried to obtain the catalyst.

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