A catalyst for preparing epsilon-caprolactone by cyclohexanone hydrogen peroxide oxidation and a preparation method and application thereof

Abstract

The application discloses a catalyst for preparing epsilon-caprolactone through cyclohexanone hydrogen peroxide oxidation, and has a structure of MgZn (x) -Ti-SBA-15 (y) The catalyst has Ti-SBA-15 as a carrier, and the molar ratio of Si to Ti is 10-100:1, wherein Mg and Zn are active components, the molar ratio of Mg to Zn is 0.5-4:1, and the mass ratio of MgO, ZnO to Ti-SBA-15 in the catalyst is 0.05-0.6. The catalyst provided by the application can improve the conversion rate and selectivity of cyclohexanone by adjusting the ratio of Mg and Zn in the active metal, and the catalyst is easy to separate under mild reaction conditions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of molecular sieve catalyst preparation, and particularly relates to a catalyst for preparing epsilon-caprolactone by oxidizing cyclohexanone with hydrogen peroxide as well as a preparation method and application thereof. BACKGROUND

[0002] Polycaprolactone is a kind of degradable material with excellent performance, good mechanical properties and biocompatibility, and is an important biomedical material. Its application fields include tissue engineering, wound repair, drug delivery, catering packaging and the like. Polycaprolactone is mainly prepared by ring-opening polymerization of epsilon-caprolactone monomer.

[0003] As an important monomer of polycaprolactone, epsilon-caprolactone can be prepared by baeyer-villiger oxidation of cyclohexanone. The oxidant attacks the carbon of the carbonyl group of cyclohexanone to form a criegee intermediate, and then the intermediate rearranges to form epsilon-caprolactone. Industrially, peroxo acid is usually used as the oxidant. However, peroxo acid is very expensive and unstable, which can easily cause explosion and has poor safety. In addition, peroxo acid can also cause excessive oxidation to produce by-products such as adipic acid and hydroxyhexanoic acid. The by-product acid can also cause ring-opening polymerization of epsilon-caprolactone, which pollutes the environment. Therefore, it is necessary to use a more environmentally friendly and safe oxidant. The by-product of hydrogen peroxide oxidation is water, so using hydrogen peroxide as an oxidant is a more environmentally friendly, green and safe choice. However, the oxidation ability of hydrogen peroxide is not as good as that of peroxo acid, so a catalyst is needed to improve the reaction efficiency.

[0004] A variety of heterogeneous catalysts have been used to catalyze the preparation of epsilon-caprolactone by oxidizing cyclohexanone with hydrogen peroxide. Corma et al. first reported Sn-beta zeolite as a catalyst for the B-V oxidation of cyclohexanone (Nature 412 (2001) 423-425). With 35% hydrogen peroxide as the oxidant and methyl tert-butyl ether and dioxane as the solvent, the catalyst showed 98% selectivity for epsilon-caprolactone, but the conversion rate was only 52%.

[0005] Zhang et al. prepared Sn-aniline complexes to catalyze the B-V oxidation of cyclohexanone (Chinese Chemical Letters 18 (2007) 4-6). With 30% hydrogen peroxide as the oxidant and dioxane as the solvent, the conversion rate of 2-adamantanone was 94%, and the selectivity of the corresponding lactone was 90%. When the substrate was cyclohexanone, the selectivity of epsilon-caprolactone reached 100%, but the conversion rate was only 30%, and the yield of the corresponding epsilon-caprolactone was only 30%.

[0006] J. Olszówka et al. used natural minerals such as magnesite containing Mg and Ca as catalysts (Appl. Catal. A 509 (2016) 52-65), acetonitrile as solvent, 30% hydrogen peroxide as oxidant, to catalyze the oxidation of cyclohexanone, and the selectivity of ε-caprolactone can reach 100%, but the conversion rate of cyclohexanone is low, and the final yield is only 40%.

[0007] Meng Qingrun synthesized Sn-Beta molecular sieve aerosol and studied its catalytic performance in the Baeyer-villiger oxidation reaction of ketones (Aerosol-assisted synthesis of Sn-Beta molecular sieve and its catalytic performance in Baeyer-villiger oxidation reaction, doctoral dissertation, Dalian University of Technology, 2020), when cyclohexanone was used as the substrate, 30% hydrogen peroxide was used as the oxidant, and dioxane was used as the solvent, the selectivity of ε-caprolactone was more than 80%, but the conversion rate was only 30%.

[0008] Luo et al. used NHPI as catalyst to directly generate hydrogen peroxide by aerobic oxidation of benzyl alcohol, and then carried out Baeyer-villiger oxidation of cyclohexanone on Sn-Beta zeolite by one-pot in-situ hydrogen peroxide, when the amount of in-situ hydrogen peroxide was 0.72 equivalent, the selectivity of ε-caprolactone was 94.8%, but the conversion rate of cyclohexanone was 39.2% (Green Chemical Engineering 2 (2021) 294-300).

[0009] Studies have shown that Zn acts as a Lewis acid in organic reactions to activate the C=X (X is a heteroatom such as O, N) bond to accept nucleophilic attack, and Mg has potential catalytic ability in the hydrogen peroxide / nitrile compound system.

[0010] In recent years, a variety of metals have been loaded into various carriers to prepare heterogeneous catalysts for B-V oxidation of cyclohexanone, but most of them have low selectivity or conversion rate, and the final yield of ε-caprolactone is not high, and Mg and Zn loaded into Ti-SBA-15 for catalyzing the oxidation of cyclohexanone with hydrogen peroxide to prepare ε-caprolactone have not been reported. SUMMARY

[0011] The purpose of the present application is to provide a catalyst for the oxidation of cyclohexanone with hydrogen peroxide to prepare ε-caprolactone, to solve the technical problems of low selectivity and low yield in the preparation of ε-caprolactone by the previous peroxide oxidation method.

[0012] Another purpose of the present application is to provide a preparation method of the catalyst for the oxidation of cyclohexanone with hydrogen peroxide to prepare ε-caprolactone.

[0013] Still another purpose of the present application is to provide an application of the catalyst in the oxidation of cyclohexanone with hydrogen peroxide to prepare ε-caprolactone.

[0014] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0015] In a first aspect, the present application provides a catalyst for preparing epsilon-caprolactone by cyclohexanone hydrogen peroxide oxidation, which has a structure of MgZn (x) -Ti-SBA-15 (y) wherein x represents the molar ratio of Mg / Zn in the catalyst, and y represents the mass ratio of MgO, ZnO to Ti-SBA-15 in the catalyst.

[0016] The catalyst prepared by the present application has a structure of MgZn (x) -Ti-SBA-15 (y) The catalyst has a carrier of Ti-SBA-15, a molar ratio of Si to Ti of 10-100:1 (preferably 10:1, 20:1, 40:1), Mg and Zn as active components, a molar ratio of Mg to Zn of 0.5-4:1 (preferably 0.5:1, 1:1, 2:1, 3:1, 4:1), and a mass ratio of MgO, ZnO to Ti-SBA-15 of 0.05-0.6 (preferably 0.1, 0.2, 0.24, 0.3, 0.32, 0.41, 0.49).

[0017] In a second aspect, the present application provides a preparation method of the catalyst, which comprises the following steps:

[0018] Firstly, disperse Ti-SBA-15 in deionized water to make its concentration 0.01-1 g / ml (preferably 0.04 g / ml), and stir for 10-60 min (preferably 30 min);

[0019] Dissolve Mg salt and Zn salt with a molar ratio of 0.5-4:1 (preferably 0.5:1, 1:1, 2:1, 3:1, 4:1) in deionized water to obtain solution A;

[0020] The mass ratio of Ti-SBA-15 to Mg salt is 0.5-4:1 (preferably 0.5:1, 0.67:1, 0.87:1, 1:1, 1.43:1, 2:1, 2.63:1);

[0021] Add solution A to the deionized water in which Ti-SBA-15 is dispersed, and stir for 10-60 min (preferably 15 min);

[0022] The Mg salt is selected from magnesium nitrate hexahydrate and magnesium chloride;

[0023] The Zn salt is selected from zinc nitrate hexahydrate and zinc chloride;

[0024] Second step, the alkaline reagent is added dropwise to the solution obtained in the first step under the condition of temperature 20-30℃ (preferably 25℃), the dropping of the alkaline reagent is stopped when the pH value is 9-11 (preferably 10), and the stirring is continued under the condition of temperature 20-30℃ (preferably 25℃) for 1-24h (preferably 24h);

[0025] The alkaline reagent is selected from sodium hydroxide and ammonia.

[0026] Third step, the solid is separated by centrifugation, the precipitate is washed with deionized water until neutral, the solid is dehydrated and dried, and is ground into fine powder, and is calcined to obtain the catalyst.

[0027] The calcination temperature is 500-600℃ (preferably 550℃), and the time is 1-8h (preferably 5h).

[0028] The preparation method of the Ti-SBA-15 comprises the following steps:

[0029] P123 is dissolved in hydrochloric acid solution with pH<1 to obtain a concentration of 0.01-1g / ml (preferably 0.043g / ml) under the condition of temperature 20-40℃ (preferably 35℃), and is stirred for 1-4h (preferably 2h), and a mixed solution of tetraethyl silicate (TEOS) and titanium-containing compound with a molar ratio of 10-100:1 (preferably 10:1, 20:1, 40:1) is added dropwise under stirring to obtain a molar ratio of Si to Ti of 10-100:1 (preferably 10:1, 20:1, 40:1), and is stirred for 10-60min (preferably 30min), and is left to react for 1-24h (preferably 24h) under the condition of temperature 20-40℃ (preferably 35℃), and is crystallized for 1-24h (preferably 24h) under the condition of temperature 70-90℃ (preferably 80℃), and the solid is separated, and is calcined to obtain Ti-SBA-15, and the mass ratio of MgO, ZnO to Ti-SBA-15 in the catalyst is 0.05-0.6 (preferably 0.1, 0.2, 0.24, 0.3, 0.32, 0.41, 0.49);

[0030] The titanium-containing compound is selected from tetraethyl titanate (TEOT), tetra-n-butyl titanate (TBOT) and titanium tetraisopropoxide (TPOT).

[0031] The calcination temperature is 500-600℃ (preferably 550℃), the time is 1-8h (preferably 5h), and the temperature rising rate is 10℃ per minute from 30℃.

[0032] In the third aspect of the present application, the catalyst is used in the preparation of ε-caprolactone by the oxidation of cyclohexanone with hydrogen peroxide.

[0033] By adopting the technical scheme, the application has the following advantages and beneficial effects:

[0034] The catalyst provided by the application has the advantages of simple preparation process, simple system, excellent selective catalytic effect for preparing epsilon-caprolactone by catalyzing the oxidation of cyclohexanone by hydrogen peroxide, and the conversion rate can be improved while the selectivity is ensured by adjusting the ratio of Mg / Zn metals, and the carrier Ti-SBA-15 of the catalyst provides more catalytic active sites by introducing Mg and Zn, thereby improving the catalytic capacity. The simple implementation method of the application has strong potential in industrial application.

[0035] The catalyst provided by the application can improve the conversion rate and selectivity of cyclohexanone by adjusting the ratio of Mg and Zn in the active metal, and the catalyst is easy to separate. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is the infrared spectrum of the catalysts of examples 6, 7 and 8.

[0037] Figure 2 is the infrared spectrum of the catalysts of examples 1, 3, 4 and 5.

[0038] Figure 3 is the infrared spectrum of the catalysts of examples 9 and 10.

[0039] Figure 4 is the scanning electron microscope image of Ti-SBA-15 (a), MgZn3-TiSBA-15 (b), MgZn3-TiSBA-15 (c) and MgZn3-TiSBA-15 (d) in examples 6, 7 and 8. 0.1 0.2 0.3

[0040] Figure 5 is the scanning electron microscope image of Ti-SBA-15 (a), Ti-SBA-15 (b), MgZn3-Ti-SBA-15 (c) and MgZn3-Ti-SBA-15 (d) in examples 8 and 9. (Si / Ti＝20) (Si / Ti＝40) (Si / Ti＝20) (Si / Ti＝40) DETAILED DESCRIPTION

[0041] In order to more clearly illustrate the application, the application will be further described below in combination with preferred examples. Those skilled in the art should understand that the specific description below is illustrative rather than limiting, and should not limit the protection scope of the application.

[0042] Example 1​​​​​​​

[0043] MgZn (4) -Ti-SBA-15 (0.49) The preparation method comprises the following steps:

[0044] Dissolve 10 g of P123 in 232 ml of hydrochloric acid solution with pH < 1, and stir for two hours until complete dissolution at a temperature of 35 ℃. Add 10 g of tetraethyl orthosilicate (TEOS) and 1.09 g of tetraethyl orthotitanate (TEOT) dropwise into the solution with a constant pressure dropping funnel under stirring, so that the molar ratio of Si / Ti is 10:1. Stir for 30 minutes, and then let the solution stand for reaction for 24 h at a temperature of 35 ℃. Crystallize for 24 h at a temperature of 80 ℃. Separate the solid, and then heat the solid from 30 ℃ to 550 ℃ at a rate of 10 ℃ per minute in an oven muffle furnace. Calcine the solid at a temperature of 550 ℃ for 5 h to remove the template agent, thereby obtaining Ti-SBA-15 (Si / Ti = 10 / 1).

[0045] In the first step, disperse 1 g of Ti-SBA-15 in 25 ml of deionized water, and stir for 30 min. Dissolve 8 mmol of magnesium nitrate hexahydrate (2.0512 g) and 2 mmol of zinc nitrate hexahydrate (0.595 g) in 15 ml of deionized water to obtain solution A. Add solution A to the deionized water in which Ti-SBA-15 is dispersed, and stir for 15 min. The mass ratio of Ti-SBA-15 to Mg salt is 1:2.

[0046] Mg and Zn exist in the form of oxides after calcination. According to the preparation of the catalyst, 8 mmol of magnesium nitrate hexahydrate and 2 mmol of zinc nitrate hexahydrate are used. Therefore, 8 mmol of MgO and 2 mmol of ZnO should be present in the catalyst after calcination, and the mass of the two oxides is 0.008 mol*40.304 g / mol (molar mass of magnesium oxide) + 0.002 mol*81.406 g / mol (molar mass of zinc oxide) = 0.485244 g, which is approximately equal to 0.49. The mass of the carrier Ti-SBA-15 is 1 g, so y = 0.49.

[0047] In the second step, add ammonia water dropwise and slowly to the solution obtained in the first step under vigorous stirring at a temperature of 25 ℃. Monitor the pH value, and stop adding ammonia water when the pH value is 10. Continue stirring at a temperature of 25 ℃ for 24 h.

[0048] In the third step, centrifugally separate the solid, wash the precipitate with 100 ml of deionized water until neutral, and then dehydrate and dry the solid in a single-tube vacuum oven or at 70 ℃. Grind the solid into fine powder, and then calcine the powder at a temperature of 550 ℃ for 5 h, thereby obtaining the catalyst MgZn (4) -Ti-SBA-15 (0.49) .

[0049] Example 2

[0050] MgZn (3) -Ti-SBA-15 (0.41) The preparation method of MgZn-Ti-SBA-15 includes the following steps:

[0051] Dissolve 10 g P123 in 232 ml hydrochloric acid solution with pH < 1, stir for two hours until completely dissolved at 35℃, add 10 g tetraethyl orthosilicate (TEOS), 1.09 g tetraethyl orthotitanate (TEOT) dropwise with a constant pressure dropping funnel under stirring to make the molar ratio of Si / Ti = 10:1, stir for 30 minutes, stand for reaction for 24 h at 35℃, crystallize for 24 h at 80℃, separate the solid, remove the template agent by calcination at 550℃ for 5 h in an oven muffle furnace with temperature rising from 30℃ to 550℃ at 10℃ per minute, and obtain Ti-SBA-15 (Si / Ti = 10 / 1).

[0052] Firstly, disperse 1 g Ti-SBA-15 in 25 ml deionized water and stir for 30 min, dissolve 6 mmol magnesium nitrate hexahydrate (1.5384 g) and 2 mmol zinc nitrate hexahydrate (0.595 g) in 15 ml deionized water to obtain solution A, add solution A to the deionized water in which Ti-SBA-15 is dispersed, and stir for 15 min. The mass ratio of Ti-SBA-15 to Mg salt is 2:3.

[0053] Secondly, add ammonia water dropwise and slowly under vigorous stirring to the solution obtained in the first step at 25℃, monitor the pH value, stop adding ammonia water when the pH value is 10, and continue stirring at 25℃ for 24 h.

[0054] Thirdly, centrifuge the solid, wash the precipitate to neutral with 100 ml deionized water, dehydrate and dry the solid with a single-row tube, grind into fine powder, and calcine at 550℃ for 5 h to obtain the catalyst MgZn-Ti-SBA-15. (3) -Ti-SBA-15 (0.41) .

[0055] Example 3

[0056] MgZn (2) -Ti-SBA-15 (0.32) The preparation method of MgZn-Ti-SBA-15 includes the following steps:

[0057] Dissolve 10 g of P123 in 232 ml of hydrochloric acid solution with pH < 1, stirring for two hours at a temperature of 35 °C until complete dissolution, add 10 g of tetraethyl orthosilicate (TEOS) and 1.09 g of tetraethyl orthotitanate (TEOT) dropwise with a constant pressure dropping funnel under stirring, so that the Si / Ti molar ratio = 10:1, stirring for 30 minutes, leaving to react at a temperature of 35 °C for 24 h, crystallization at a temperature of 80 °C for 24 h, separation of the solid, calcination at a temperature of 550 °C for 5 h to remove the template by increasing the temperature from 30 °C to 550 °C at 10 °C per minute in an oven muffle, to obtain Ti-SBA-15 (Si / Ti = 10 / 1).

[0058] First step, disperse 1 g of Ti-SBA-15 in 25 ml of deionized water, stirring for 30 min, dissolve 4 mmol of magnesium nitrate hexahydrate (1.0256 g) and 2 mmol of zinc nitrate hexahydrate (0.595 g) in 15 ml of deionized water to obtain solution A, add solution A to the Ti-SBA-15 dispersion in deionized water, stirring for 15 min. The mass ratio of Ti-SBA-15 to Mg salt is 1:1.

[0059] Second step, add ammonia to the solution obtained in the first step dropwise and slowly under vigorous stirring at a temperature of 25 °C, monitor the pH value, stop adding ammonia when the pH value is 10, continue stirring at a temperature of 25 °C for 24 h.

[0060] Third step, centrifuge the solid, wash the precipitate with 100 ml of deionized water until neutral, dry the solid by single-tube dehydration, grind into fine powder, calcine at a temperature of 550 °C for 5 h to obtain the catalyst MgZn (2) -Ti-SBA-15 (0.32) .

[0061] Example 4

[0062] MgZn (1) -Ti-SBA-15 (0.24) The preparation method of the catalyst MgZn

[0063] Dissolve 10 g of P123 in 232 ml of hydrochloric acid solution with pH < 1, stirring for 2 hours at 35 °C until complete dissolution, add 10 g of tetraethyl orthosilicate (TEOS), 1.09 g of tetraethyl orthotitanate (TEOT) dropwise with a constant pressure dropping funnel under stirring to obtain a Si / Ti molar ratio = 10:1, stir for 30 minutes, let it react at 35 °C for 24 h, crystallize at 80 °C for 24 h, separate the solid, calcine at 550 °C for 5 h to remove the template by increasing the temperature from 30 °C to 550 °C at 10 °C per minute in an oven muffle, to obtain Ti-SBA-15 (Si / Ti = 10 / 1).

[0064] First step, disperse 1 g of Ti-SBA-15 in 25 ml of deionized water, stir for 30 min, dissolve 2 mmol of magnesium nitrate hexahydrate (0.5128 g) and 2 mmol of zinc nitrate hexahydrate (0.595 g) in 15 ml of deionized water to obtain solution A, add solution A to the Ti-SBA-15 dispersion in deionized water, stir for 15 min. The mass ratio of Ti-SBA-15 to Mg salt is 2:1.

[0065] Second step, add ammonia dropwise and slowly under vigorous stirring to the solution obtained in the first step at 25 °C, monitor the pH value, stop adding ammonia when the pH value is 10, continue stirring at 25 °C for 24 h.

[0066] Third step, centrifuge the solid, wash the precipitate with 100 ml of deionized water until neutral, dry the solid by single-tube dehydration, grind it into fine powder, calcine at 550 °C for 5 h to obtain the catalyst MgZn (1) -Ti-SBA-15 (0.24) .

[0067] Example 5

[0068] MgZn (0.5) -Ti-SBA-15 (0.41) The preparation method of the catalyst MgZn

[0069] Dissolve 10 g of P123 in 232 ml of hydrochloric acid solution with pH < 1, stirring for 2 hours at 35 °C until complete dissolution, add 10 g of tetraethyl orthosilicate (TEOS), 1.09 g of tetraethyl orthotitanate (TEOT) dropwise with a constant pressure dropping funnel under stirring to make the Si / Ti molar ratio = 10:1, stirring for 30 minutes, standing for 24 h at 35 °C, crystallization for 24 h at 80 °C, separating the solid, calcination for 5 h at 550 °C to remove the template agent by increasing the temperature from 30 °C to 550 °C at 10 °C per minute in an oven muffle, to obtain Ti-SBA-15 (Si / Ti = 10 / 1).

[0070] First step, disperse 1 g of Ti-SBA-15 in 25 ml of deionized water, stirring for 30 min, dissolve magnesium nitrate hexahydrate (2 mmol, 0.5128 g), zinc nitrate hexahydrate (4 mmol, 1.19 g) in 15 ml of deionized water to obtain solution A, add solution A to the dispersed Ti-SBA-15 in deionized water, stirring for 15 min. The mass ratio of Ti-SBA-15 to Mg salt is 2:1.

[0071] Second step, add ammonia water dropwise and slowly under vigorous stirring to the solution obtained in the first step at 25 °C, monitor the pH value, stop adding ammonia water when the pH value is 10, continue stirring at 25 °C for 24 h.

[0072] Third step, centrifugal separation of the solid, wash the precipitate to neutral with 100 ml of deionized water, dry the solid with a single row tube, grind into fine powder, calcine for 5 h at 550 °C to obtain the catalyst MgZn (0.5) -Ti-SBA-15 (0.41) .

[0073] Example 6

[0074] MgZn (3) -Ti-SBA-15 (0.3) The preparation method of the catalyst MgZn

[0075] Dissolve 10 g of P123 in 232 ml of hydrochloric acid solution with pH < 1, stirring for 2 hours at 35 °C until complete dissolution, add 10 g of tetraethyl orthosilicate (TEOS) and 1.09 g of tetraethyl orthotitanate (TEOT) dropwise with a constant pressure dropping funnel under stirring, so that the Si / Ti molar ratio = 10:1, stirring for 30 minutes, standing for 24 h at 35 °C, crystallization for 24 h at 80 °C, separation of the solid, calcination for 5 h at 550 °C to remove the template agent by increasing the temperature from 30 °C to 550 °C at 10 °C per minute in an oven muffle, to obtain Ti-SBA-15 (Si / Ti = 10 / 1).

[0076] First step, disperse 1 g of Ti-SBA-15 in 25 ml of deionized water, stirring for 30 min, dissolve 4.5 mmol of magnesium nitrate hexahydrate (1.1538 g) and 1.5 mmol of zinc nitrate hexahydrate (0.4463 g) in 15 ml of deionized water to obtain solution A, add solution A to the Ti-SBA-15 dispersion in deionized water, stirring for 15 min. The mass ratio of Ti-SBA-15 to Mg salt is 1:1.15.

[0077] Second step, add ammonia water dropwise and slowly under vigorous stirring to the solution obtained in the first step at 25 °C, monitor the pH value, stop adding ammonia water when the pH value is 10, continue stirring at 25 °C for 24 h.

[0078] Third step, centrifuge the solid, wash the precipitate with 100 ml of deionized water until neutral, dry the solid by single-tube dehydration, grind into fine powder, calcine at 550 °C for 5 h to obtain the catalyst MgZn (3) -Ti-SBA-15 (0.3) .

[0079] Example 7

[0080] MgZn (3) -Ti-SBA-15 (0.2) The preparation method of the catalyst MgZn

[0081] Dissolve 10 g of P123 in 232 ml of hydrochloric acid solution with pH < 1, stirring for 2 hours at 35 °C until complete dissolution, add 10 g of tetraethyl orthosilicate (TEOS), 1.09 g of tetraethyl orthotitanate (TEOT) dropwise with a constant pressure dropping funnel under stirring to make the Si / Ti molar ratio = 10:1, stirring for 30 minutes, standing for 24 h at 35 °C, crystallization for 24 h at 80 °C, separating the solid, calcination for 5 h at 550 °C to remove the template agent by increasing the temperature from 30 °C to 550 °C at 10 °C per minute in an oven muffle, to obtain Ti-SBA-15 (Si / Ti = 10 / 1).

[0082] First step, disperse 1 g of Ti-SBA-15 in 25 ml of deionized water, stirring for 30 min, dissolve magnesium nitrate hexahydrate (3 mmol, 0.7692 g), zinc nitrate hexahydrate (1 mmol, 0.2975 g) in 15 ml of deionized water to obtain solution A, add solution A to the dispersed Ti-SBA-15 in deionized water, stirring for 15 min. The mass ratio of Ti-SBA-15 to Mg salt is 10:7.

[0083] Second step, add ammonia water dropwise and slowly under vigorous stirring to the solution obtained in the first step at 25 °C, monitor the pH value, stop adding ammonia water when the pH value is 10, continue stirring at 25 °C for 24 h.

[0084] Third step, centrifugal separation of the solid, wash the precipitate to neutral with 100 ml of deionized water, dry the solid with a single row tube, grind into fine powder, calcine for 5 h at 550 °C to obtain the catalyst MgZn (3) -Ti-SBA-15 (0.2) .

[0085] Example 8

[0086] MgZn (3) -Ti-SBA-15 (0.1) The preparation method of the catalyst MgZn

[0087] Dissolve 10 g of P123 in 232 ml of hydrochloric acid solution with pH < 1, stirring for 2 hours at 35 °C until complete dissolution, add 10 g of tetraethyl orthosilicate (TEOS) and 1.09 g of tetraethyl orthotitanate (TEOT) dropwise with a constant pressure dropping funnel under stirring to obtain a Si / Ti molar ratio = 10:1, stirring for 30 minutes, leaving to react for 24 h at 35 °C, crystallizing for 24 h at 80 °C, separating the solid, calcining for 5 h at 550 °C to remove the template agent by increasing the temperature from 30 °C to 550 °C at 10 °C per minute in an oven muffle, to obtain Ti-SBA-15 (Si / Ti = 10 / 1).

[0088] First step, disperse 1 g of Ti-SBA-15 in 25 ml of deionized water, stirring for 30 min, dissolve 1.5 mmol of magnesium nitrate hexahydrate (0.3846 g) and 0.5 mmol of zinc nitrate hexahydrate (0.1487 g) in 15 ml of deionized water to obtain solution A, add solution A to the Ti-SBA-15 dispersion in deionized water, stirring for 15 min. The mass ratio of Ti-SBA-15 to Mg salt is 1:0.38.

[0089] Second step, add ammonia to the solution obtained in the first step dropwise and slowly under vigorous stirring at 25 °C, monitor the pH value, stop adding ammonia when the pH value is 10, continue stirring for 24 h at 25 °C.

[0090] Third step, centrifuge the solid, wash the precipitate with 100 ml of deionized water until neutral, dry the solid by single-tube dehydration, grind into fine powder, calcine for 5 h at 550 °C to obtain the catalyst MgZn (3) -Ti-SBA-15 (0.1) .

[0091] Example 9

[0092] MgZn (3) -Ti-SBA-15 (0.3) The preparation method of the catalyst MgZn

[0093] Dissolve 10 g of P123 in 232 ml of hydrochloric acid solution with pH < 1, stirring for 2 hours until complete dissolution at a temperature of 35 °C, add 10 g of tetraethyl orthosilicate (TEOS) and 0.545 g of tetraethyl orthotitanate (TEOT) dropwise with a constant pressure dropping funnel under stirring for 30 minutes, so that the Si / Ti molar ratio = 20:1, let it react for 24 h at rest at a temperature of 35 °C, crystallize for 24 h at a temperature of 80 °C, separate the solid, calcine it at a temperature of 550 °C for 5 h in an oven muffle, increasing the temperature from 30 °C to 550 °C at 10 °C per minute, to remove the template, obtaining Ti-SBA-15 (Si / Ti = 20 / 1).

[0094] First step, disperse 1 g of Ti-SBA-15 (Si / Ti = 20 / 1) in 25 ml of deionized water, stirring for 30 min, dissolve magnesium nitrate hexahydrate (4.5 mmol, 1.1538 g) and zinc nitrate hexahydrate (1.5 mmol, 0.4463 g) in 15 ml of deionized water to obtain solution A, add solution A to the deionized water in which Ti-SBA-15 is dispersed, stirring for 15 min. The mass ratio of Ti-SBA-15 (Si / Ti = 20 / 1) to Mg salt is 1:1.15;

[0095] Second step, add ammonia water dropwise and slowly under vigorous stirring to the solution obtained in the first step at a temperature of 25 °C, monitoring the pH value, stop adding ammonia water when the pH value is 10, continue stirring for 24 h at a temperature of 25 °C.

[0096] Third step, centrifuge the solid, wash the precipitate with 100 ml of deionized water until neutral, dry the solid with a single-tube dehydration dryer, grind it into fine powder, calcine it at a temperature of 550 °C for 5 h, obtaining the catalyst MgZn (3) -Ti-SBA-15 (0.3) .

[0097] Example 10

[0098] MgZn (3) -Ti-SBA-15 (0.3) The method for preparing MgZn

[0099] Dissolve 10 g P123 in 232 ml hydrochloric acid solution with pH < 1, stirring for 2 hours at 35℃ until complete dissolution, add 10 g tetraethyl orthosilicate (TEOS), 0.2725 g tetraethyl orthotitanate (TEOT) dropwise with a constant pressure dropping funnel under stirring for 30 minutes, so that the molar ratio of Si / Ti = 40:1, let it stand for 24 hours at 35℃, crystallize for 24 hours at 80℃, separate the solid, heat from 30℃ to 550℃ at 10℃ per minute in an oven muffle furnace, calcine for 5 hours at 550℃ to remove the template, to obtain Ti-SBA-15 (Si / Ti = 40 / 1).

[0100] First step, disperse 1 g Ti-SBA-15 (Si / Ti = 40 / 1) in 25 ml deionized water, stirring for 30 min, dissolve magnesium nitrate hexahydrate (4.5 mmol, 1.1538 g), zinc nitrate hexahydrate (1.5 mmol, 0.4463 g) in 15 ml deionized water to obtain solution A, add solution A to the dispersed Ti-SBA-15 in deionized water, stirring for 15 min. The mass ratio of Ti-SBA-15 (Si / Ti = 40 / 1) to Mg salt is 1:1.15.

[0101] Second step, add ammonia water dropwise and slowly under vigorous stirring to the solution obtained in the first step at 25℃, monitor the pH value, stop adding ammonia water when the pH value is 10, continue stirring for 24 hours at 25℃.

[0102] Third step, centrifuge the solid, wash the precipitate to neutral with 100 ml deionized water, dehydrate the solid with a single row tube, grind into fine powder, calcine for 5 hours at 550℃ to obtain the catalyst MgZn (3) -Ti-SBA-15 (0.3) .

[0103] The infrared spectrum of the catalyst prepared in the examples is shown in Figure 1 、 Figure 2 、 Figure 3 , Figure 1 which is the infrared spectrum of the catalysts of examples 6, 7, 8. Figure 2 which is the infrared spectrum of the catalysts of examples 1, 3, 4, 5. Figure 3 which is the infrared spectrum of the catalysts of examples 9, 10. After the incorporation of Ti and the loading of Mg, Zn, the intensity of the Si-OH vibration peak corresponding to 960 cm -1 in the infrared spectrum decreases significantly or disappears, indicating the combination of Mg, Zn, Ti with Si-OH. The scanning electron microscope images of examples 6, 7, 8, 9, 10 are shown in Figure 4 ,Figure 5 As shown, Figure 4 is Ti-SBA-15(a), MgZn3-TiSBA-15 0.1 (b), MgZn3-TiSBA-15 0.2 (c), MgZn3-TiSBA-15 0.3 (d) of Example 6, 7, 8. Figure 5 is Ti-SBA-15(a), Ti-SBA-15 (Si / Ti＝20) (b), MgZn3-Ti-SBA-15 (Si / Ti＝40) (c), MgZn3-Ti-SBA-15 (Si / Ti＝20) (d) of Example 8, 9. (Si / Ti＝40) (d) of Example 8, 9. As can be seen from the figure, the catalyst appears as a sphere, the Ti-SBA-15 microspheres without Mg and Zn loading appear as a sphere with smooth surface, and the microspheres after loading appear many irregular particles on the surface, which are MgO and ZnO formed on the surface, indicating that Mg and Zn are successfully loaded on the surface of the carrier.

[0104] Application Example 1

[0105] Evaluation reaction of the catalyst prepared in the examples of the present application on the catalytic effect of hydrogen peroxide oxidation of cyclohexanone

[0106] In a three-necked flask with a serpentine condenser reflux tube, cyclohexanone (2 mmol, 0.19 g), benzonitrile (8 mmol, 0.82 g), 30% mass fraction hydrogen peroxide (the molar amount of hydrogen peroxide is 7.5 mmol, 1.14 g), 2.84 ml acetonitrile, 9.8 mg of the catalyst prepared in the examples of the present application, and 16 mg of sodium bicarbonate were added, and the reaction was carried out at a temperature of 80℃ for 10 h to obtain ε-caprolactone. 100 microliters of the solution before and after the reaction were taken respectively, diluted with ethyl acetate to 10 ml, and used for analysis by Shimadzu GC-2010 gas chromatograph. The initial molar concentration C cyc0 of cyclohexanone was detected, the molar concentration C cyc1 of cyclohexanone at the time of sampling after the reaction, and the molar concentration C ε-cl of ε-caprolactone at the time of sampling after the reaction were detected.

[0107] The corresponding conversion rate, yield, and selectivity were calculated by the following formula:

[0108] The conversion rate of cyclohexanone = (C cyc0 -C cyc1 ) / C cyc0 * 100%;

[0109] The yield of ε-caprolactone = C ε-cl / C cyc0* 100%;

[0110] The selectivity of the product to caprolactone = the conversion rate of ε-caprolactone / cyclohexanone * 100%.

[0111] The catalysts prepared in Examples 1-10 were applied to the catalysis of the oxidation of cyclohexanone by hydrogen peroxide to prepare ε-caprolactone, and the reaction results were all data after the reaction reached a stable state, and the results are shown in Table 1:

[0112] Table 1 Catalytic effect of catalysts with different Mg / Zn metal ratios

[0113] Catalyst Conversion Selectivity Yield Example 1 MgZn4-Ti-SBA-15 (0.49) ]]> 68.47％ 60.98％ 41.75％ Example 2 MgZn3-Ti-SBA-15 (0.41) ]]> 84.49％ 96.73％ 81.73％ Example 3 MgZn2-Ti-SBA-15 (0.32) ]]> 69.19％ 69.26％ 47.92％ Example 4 MgZn1-Ti-SBA-15 (0.24) ]]> 71.41％ 60.50％ 43.20％ Example 5 MgZn 0.5 -Ti-SBA-15 (0.41) ]]> 85.72％ 63.47％ 54.40％

[0114] Table 2 Catalytic effect of different metal oxide / support ratios

[0115] Catalyst Conversion Selectivity Yield Example 2 MgZn3-Ti-SBA-15 (0.41) ]]> 84.49％ 96.73％ 81.73％ Example 6 MgZn3-Ti-SBA-15 (0.3) ]]> 90.93％ 92.55％ 84.15％ Example 7 MgZn3-Ti-SBA-15 (0.2) ]]> 82.39％ 97.12％ 80.01％ Example 8 MgZn3-Ti-SBA-15 (0.1) ]]> 80.47％ 90.55％ 72.87％

[0116] Table 3 Catalytic effect of different support Si / Ti ratios

[0117] Catalyst Conversion Selectivity Yield Example 6 MgZn3-Ti-SBA-15 (0.3) Si / Ti = 10 / 1 90.93％ 92.55％ 84.15％ Example 9 MgZn3-Ti-SBA-15 (0.3) Si / Ti = 20 / 1 81.26％ 91.81％ 74.60％ Example 10 MgZn3-Ti-SBA-15 (0.3) Si / Ti = 40 / 1 77.09％ 91.96％ 70.89％

[0118] In Tables 1-3, the conversion rate refers to the conversion rate of cyclohexanone; the selectivity refers to the selectivity of the product to caprolactone, and the yield refers to the yield of ε-caprolactone.

[0119] As can be seen from the results in Tables 1, 2, and 3, by adjusting the ratio of the two metals in the catalyst, the ratio of the support to the active species, and the silicon / titanium ratio in the support, a higher conversion rate and selectivity can be obtained in the reaction of preparing ε-caprolactone by the oxidation of cyclohexanone by hydrogen peroxide. When the molar ratio of Mg / Zn is 0.5, the conversion rate of cyclohexanone is as high as 85.72%, but the selectivity is only 63.47%. When the molar ratio of Mg / Zn is 3, the highest conversion rate of cyclohexanone is 90.93% and the selectivity is 92.55% (when the mass ratio of MgO, ZnO to the support is 0.3 and the silicon / titanium ratio of the support is 10). The catalyst prepared in the examples is a highly efficient heterogeneous catalyst for preparing ε-caprolactone from cyclohexanone in a hydrogen peroxide system.

[0120] The above description is only the preferred embodiments of the present application and is not intended to limit the present application in any form. Although the present application has been disclosed as above with the preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make some changes or modifications to the above-mentioned technical content without departing from the technical solution range of the present application to make equivalent embodiments with equivalent changes. Any simple modification, equivalent change, and modification made to the above embodiments according to the technical essence of the present application are still within the scope of the present application.

Claims

1. A catalyst for the production of ε-caprolactone by the oxidation of cyclohexanone with hydrogen peroxide, characterized in that, The structure is MgZn (x) -Ti-SBA-15 (y) wherein x represents the molar ratio of Mg / Zn in the catalyst, and y represents the mass ratio of MgO, ZnO to Ti-SBA-15 in the catalyst. The Ti-SBA-15 is used as a carrier, the molar ratio of Si to Ti is 10-100:1, the MgO and ZnO are active components, the molar ratio of Mg to Zn is 3:1, and the mass ratio of MgO, ZnO to Ti-SBA-15 in the catalyst is 0.05-0.

6.

2. A process for the preparation of the catalyst according to claim 1, characterized in that, The method comprises the following steps: In the first step, the Ti-SBA-15 is dispersed in deionized water to have a concentration of 0.01-1 g / ml, and stirred for 10-60 min; The Mg salt and Zn salt with a molar ratio of 3:1 are dissolved in deionized water to obtain solution A; The mass ratio of Ti-SBA-15 to Mg salt is 0.5-4:1; Solution A is added to the deionized water in which the Ti-SBA-15 is dispersed, and stirred for 10-60 min; In the second step, the alkaline reagent is added dropwise to the solution obtained in the first step under the condition that the temperature is 20-30 ℃, and the dropping is stopped when the pH value is monitored to be 9-11, and the stirring is continued for 1-24 h under the condition that the temperature is 20-30 ℃; In the third step, the solid is separated by centrifugation, the precipitate is washed with deionized water until neutral, the solid is dehydrated and dried, ground into fine powder, and calcined to obtain the catalyst.

3. The method of claim 2, wherein the catalyst is prepared by the steps of: The Mg salt is selected from magnesium nitrate hexahydrate and magnesium chloride.

4. The method of claim 2, wherein the catalyst is prepared by the steps of: The Zn salt is selected from zinc nitrate hexahydrate and zinc chloride.

5. The method of claim 2, wherein the catalyst is prepared by the steps of: The alkaline reagent is selected from sodium hydroxide and ammonia.

6. The method of claim 2, wherein the catalyst is prepared by the steps of: The calcination temperature is 500-600 ℃, and the time is 1-8 h.

7. The method of claim 2, wherein the catalyst is prepared by the steps of: The preparation method of the Ti-SBA-15 comprises the following steps: The P123 is dissolved in a hydrochloric acid solution with pH<1 to have a concentration of 0.01-1 g / ml, stirred for 1-4 h under the condition that the temperature is 20-40 ℃, a mixed solution of tetraethyl silicate and titanium-containing compound with a molar ratio of 10-100:1 is added dropwise under stirring to have a molar ratio of Si to Ti of 10-100:1, stirred for 10-60 min, and then reacted for 1-24 h under the condition that the temperature is 20-40 ℃, crystallized for 1-24 h under the condition that the temperature is 70-90 ℃, the solid is separated, and calcined to obtain the Ti-SBA-15, and the mass ratio of MgO, ZnO to Ti-SBA-15 in the catalyst is 0.05-0.6; The titanium-containing compound is selected from tetraethyl titanate, tetra-n-butyl titanate and titanium tetraisopropoxide.

8. The method of claim 7, wherein the catalyst is prepared by a method comprising: In the preparation of the Ti-SBA-15, the calcination temperature is 500-600 ℃, the time is 1-8 h, and the temperature rising rate is 10 ℃ per minute from 30 ℃.

9. The use of the catalyst prepared by the method of any one of claims 2 to 8 in the preparation of ε-caprolactone by the oxidation of cyclohexanone with hydrogen peroxide.

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