Catalyst for preparing epsilon-caprolactone through cyclohexanone hydrogen peroxide oxidation as well as preparation method and application of catalyst

Abstract

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

Description

Technical Field

[0001] The invention belongs to the technical field of molecular sieve catalyst preparation, and specifically relates to a catalyst for preparing epsilon-caprolactone by oxidizing cyclohexanone with hydrogen peroxide, and a preparation method and application thereof. Background Art

[0002] Polycaprolactone is a biodegradable material with excellent performance, good mechanical properties and biocompatibility. It is an important biomedical material. Its application areas include tissue engineering, wound repair, drug delivery, catering packaging, etc. Polycaprolactone is mainly prepared by ring-opening polymerization of ε-caprolactone monomer.

[0003] As an important monomer of polycaprolactone, ε-caprolactone can be prepared by Baeyer-Villiger oxidation of cyclohexanone. The oxidant forms a criegee intermediate by attacking the carbon on the carbonyl group of cyclohexanone, and then the intermediate is rearranged to generate ε-caprolactone. Peroxy acid is usually used as an oxidant in industry, but the cost of peroxy acid is very high, and it is unstable and easy to cause explosion, poor safety, and excessive oxidation will produce by-products such as adipic acid and hydroxycaproic acid. The by-product acid produced is also easy to cause the ring-opening polymerization of ε-caprolactone, which pollutes the environment. Therefore, it is very necessary to use a more environmentally friendly and safe oxidant, and the by-product is water when using hydrogen peroxide oxidation, so using hydrogen peroxide as an oxidant is a more environmentally friendly, green and safe choice. However, the oxidizing ability of hydrogen peroxide is not as good as that of peroxy acid, so it is necessary to improve the reaction efficiency by a catalyst.

[0004] A variety of heterogeneous catalysts have been used to catalyze the oxidation of cyclohexanone with hydrogen peroxide to prepare ε-caprolactone. Corma et al. first reported Sn-β zeolite as a catalyst for the BV oxidation of cyclohexanone (Nature 412 (2001) 423–425). Using 35% hydrogen peroxide as an oxidant and methyl tert-butyl ether and dioxane as solvents, they showed 98% selectivity for ε-caprolactone, but the conversion rate was only 52%.

[0005] Zhang et al. prepared a Sn-aniline complex to catalyze the oxidation of cyclic ketone BV (Chinese Chemical Letters 18(2007)4–6). Using 30% hydrogen peroxide as the oxidant and dioxane as the solvent, the reaction was carried out with a conversion rate of 94% for 2-adamantanone and a selectivity of 90% for the corresponding lactone. When the substrate was cyclohexanone, the selectivity for ε-caprolactone reached 100%, but the conversion rate was only 30%, and the corresponding yield of ε-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, and 30% hydrogen peroxide as oxidant to catalytically oxidize cyclohexanone. 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 an aerosol of Sn-Beta molecular sieve and studied its catalytic performance in the Baeyer-villiger oxidation reaction of ketones (Aerosol-assisted synthesis of Sn-Beta molecular sieves and study of their catalytic performance in the Baeyer-villiger oxidation reaction, PhD 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 for ε-caprolactone exceeded 80%, but the conversion rate was only 30%.

[0008] Luo et al. directly generated hydrogen peroxide by aerobic oxidation of benzyl alcohol under NHPI catalysis, and carried out Bayer-Villiger oxidation of cyclohexanone by one-pot in situ hydrogen peroxide on Sn-Beta zeolite. When the amount of in situ hydrogen peroxide was 0.72 equivalents, 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, as a Lewis acid, activates C=X (X is a heteroatom such as O, N, etc.) bonds in organic reactions to accept attacks by nucleophiles, and Mg exhibits potential catalytic ability in hydrogen peroxide / nitrile compound systems.

[0010] In recent years, a variety of metals have been loaded into various carriers to prepare heterogeneous catalysts for catalyzing the BV oxidation reaction of cyclohexanone. However, most of them have low selectivity or conversion rate, and the final yield of ε-caprolactone is not high. There are no reports on Mg and Zn being loaded into Ti-SBA-15 to catalyze the hydrogen peroxide oxidation of cyclohexanone to prepare ε-caprolactone. Summary of the invention

[0011] The purpose of the present invention is to provide a catalyst for preparing ε-caprolactone by oxidizing cyclohexanone with hydrogen peroxide, so as to solve the technical problems of low selectivity and low yield of preparing ε-caprolactone by the previous hydrogen peroxide oxidation method.

[0012] Another object of the present invention is to provide a method for preparing the catalyst for preparing ε-caprolactone by oxidizing cyclohexanone with hydrogen peroxide.

[0013] Another object of the present invention is to provide an application of the catalyst in the preparation of ε-caprolactone by oxidation of cyclohexanone with hydrogen peroxide.

[0014] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0015] In the first aspect of the present invention, there is provided a catalyst for preparing ε-caprolactone by oxidation of cyclohexanone with hydrogen peroxide, the structure of which 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 and Ti-SBA-15 in the catalyst.

[0016] The catalyst prepared by the present invention is MgZn (x) -Ti-SBA-15 (y) , Ti-SBA-15 is used as a carrier, the molar ratio of Si to Ti is 10-100:1 (preferably 10:1, 20:1, 40:1), wherein Mg and Zn are active ingredients, the molar ratio of Mg to Zn is 0.5-4:1 (preferably 0.5:1, 1:1, 2:1, 3:1, 4:1), and the mass ratio of MgO, ZnO and 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).

[0017] The second aspect of the present invention provides a method for preparing the catalyst, comprising the following steps:

[0018] The first step is to disperse Ti-SBA-15 in deionized water to a concentration of 0.01 to 1 g / ml (preferably 0.04 g / ml) and stir for 10 to 60 min (preferably 30 min);

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

[0020] The mass ratio of Ti-SBA-15 to Mg salt is 0.5 to 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 to 60 minutes (preferably 15 minutes);

[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] Step 2: add the alkaline reagent dropwise to the solution obtained in the first step at a temperature of 20 to 30° C. (preferably 25° C.), stop adding the alkaline reagent dropwise when the pH value is 9 to 11 (preferably 10), and continue stirring at a temperature of 20 to 30° C. (preferably 25° C.) for 1 to 24 hours (preferably 24 hours);

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

[0026] The third step is to separate the solid by centrifugation, wash the precipitate with deionized water until it is neutral, dehydrate and dry the solid, grind it into fine powder, and calcine it to obtain the catalyst.

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

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

[0029] P123 is dissolved in a hydrochloric acid solution with a pH value less than 1 to a concentration of 0.01 to 1 g / ml (preferably 0.043 g / ml), and the mixture is stirred for 1 to 4 hours (preferably 2 hours) at a temperature of 20 to 40° C. (preferably 35° C.). A mixed solution of tetraethyl silicate (TEOS) and a titanium-containing compound at a molar ratio of 10 to 100:1 (preferably 10:1, 20:1, 40:1) is added dropwise under stirring to make the molar ratio of Si to Ti 10 to 100:1 (preferably 10:1, 20:1, 40:1), and stirred. 10 to 60 minutes (preferably 30 minutes), at a temperature of 20 to 40° C. (preferably 35° C.), standing for reaction for 1 to 24 hours (preferably 24 hours), at a temperature of 70 to 90° C. (preferably 80° C.) for crystallization for 1 to 24 hours (preferably 24 hours), separating the solid, and calcining to obtain Ti-SBA-15, wherein the mass ratio of MgO, ZnO and Ti-SBA-15 in the catalyst is 0.05 to 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), tetrabutyl titanate (TBOT), and titanium tetraisopropoxide (TPOT).

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

[0032] The third aspect of the present invention provides a use of the catalyst in the preparation of ε-caprolactone by oxidation of cyclohexanone with hydrogen peroxide.

[0033] Due to the adoption of the above technical solution, the present invention has the following advantages and beneficial effects:

[0034] The catalyst preparation process provided by the present invention is easy to operate and has a simple system. It is used for catalyzing the oxidation of cyclohexanone with hydrogen peroxide to prepare ε-caprolactone and exhibits excellent selective catalytic effect. By adjusting the ratio of Mg / Zn metal, the conversion rate can be improved while ensuring high selectivity. The carrier Ti-SBA-15 of the catalyst provides more catalytic active sites due to the introduction of Mg and Zn, thereby improving its catalytic ability. The simple implementation method of the present invention makes it have strong potential in industrial-scale application.

[0035] The catalyst provided by the invention can improve the conversion rate and selectivity of cyclohexanone by adjusting the ratio of Mg and Zn in the active metals, and the reaction conditions are mild and the catalyst is easy to separate. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is the infrared spectra of the catalysts of Examples 6, 7 and 8.

[0037] Figure 2 It is the infrared spectra of the catalysts of Examples 1, 3, 4 and 5.

[0038] Figure 3 It is the infrared spectra of the catalysts of Examples 9 and 10.

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

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

[0041] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0042] Example 1

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

[0044] Dissolve 10g P123 in 232ml hydrochloric acid solution with pH<1, stir for two hours at 35°C until completely dissolved, add 10g tetraethyl silicate (TEOS) and 1.09g tetraethyl titanate (TEOT) dropwise with a constant pressure dropping funnel while stirring, so that the Si / Ti molar ratio is 10:1, stir for 30 minutes, let the reaction stand at 35°C for 24h, crystallize at 80°C for 24h, separate the solid, and heat from 30°C to 550°C at 10°C per minute in an oven-type muffle furnace, calcine at 550°C for 5h to remove the template to obtain Ti-SBA-15 (Si / Ti=10 / 1).

[0045] In the first step, 1g Ti-SBA-15 was dispersed in 25ml deionized water and stirred for 30min. Magnesium nitrate hexahydrate (8mmol, 2.0512g) and zinc nitrate hexahydrate (2mmol, 0.595g) were fully dissolved in 15ml deionized water to obtain solution A. Solution A was added to the deionized water in which Ti-SBA-15 was dispersed and stirred for 15min. The mass ratio of Ti-SBA-15 to Mg salt was 1:2.

[0046] Mg and Zn exist in the form of oxides after calcination. When preparing the catalyst, magnesium nitrate hexahydrate is 8 mmol and zinc nitrate hexahydrate is 2 mmol. Then, after calcination, the catalyst should contain 8 mmol MgO and 2 mmol ZnO. The mass of the catalyst 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, at a temperature of 25°C, slowly and dropwise add ammonia water to the solution obtained in the first step under vigorous stirring, monitor the pH value, and stop adding ammonia water when the pH value reaches 10, and continue stirring at a temperature of 25°C for 24 hours.

[0048] The third step is to separate the solid by centrifugation, wash the precipitate with 100 ml of deionized water until it is neutral, dehydrate and dry the solid with a single-row tube or a vacuum oven at 70°C, grind it into fine powder, and calcine it at 550°C for 5 hours to obtain the catalyst MgZn (4) -Ti-SBA-15 (0.49) .

[0049] Example 2

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

[0051] Dissolve 10g P123 in 232ml hydrochloric acid solution with pH<1, stir for two hours at 35°C until completely dissolved, add 10g tetraethyl silicate (TEOS) and 1.09g tetraethyl titanate (TEOT) dropwise with a constant pressure dropping funnel while stirring, so that the Si / Ti molar ratio is 10:1, stir for 30 minutes, let the reaction stand at 35°C for 24h, crystallize at 80°C for 24h, separate the solid, and heat from 30°C to 550°C at 10°C per minute in an oven-type muffle furnace, calcine at 550°C for 5h to remove the template to obtain Ti-SBA-15 (Si / Ti=10 / 1).

[0052] In the first step, 1g Ti-SBA-15 was dispersed in 25ml deionized water and stirred for 30min. Magnesium nitrate hexahydrate (6mmol, 1.5384g) and zinc nitrate hexahydrate (2mmol, 0.595g) were fully dissolved in 15ml deionized water to obtain solution A. Solution A was added to the deionized water in which Ti-SBA-15 was dispersed and stirred for 15min. The mass ratio of Ti-SBA-15 to Mg salt was 2:3.

[0053] In the second step, at a temperature of 25°C, slowly and dropwise add ammonia water to the solution obtained in the first step under vigorous stirring, monitor the pH value, and stop adding ammonia water when the pH value reaches 10, and continue stirring at a temperature of 25°C for 24 hours.

[0054] The third step is to separate the solid by centrifugation, wash the precipitate with 100 ml of deionized water until it is neutral, dehydrate and dry the solid with a single-row tube, grind it into fine powder, and calcine it at 550 ° C for 5 h to obtain the catalyst MgZn (3) -Ti-SBA-15 (0.41) .

[0055] Example 3

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

[0057] Dissolve 10g P123 in 232ml hydrochloric acid solution with pH<1, stir for two hours at 35°C until completely dissolved, add 10g tetraethyl silicate (TEOS) and 1.09g tetraethyl titanate (TEOT) dropwise with a constant pressure dropping funnel while stirring, so that the Si / Ti molar ratio is 10:1, stir for 30 minutes, let the reaction stand at 35°C for 24h, crystallize at 80°C for 24h, separate the solid, and heat from 30°C to 550°C at 10°C per minute in an oven-type muffle furnace, calcine at 550°C for 5h to remove the template to obtain Ti-SBA-15 (Si / Ti=10 / 1).

[0058] In the first step, 1g Ti-SBA-15 was dispersed in 25ml deionized water and stirred for 30min. Magnesium nitrate hexahydrate (4mmol, 1.0256g) and zinc nitrate hexahydrate (2mmol, 0.595g) were fully dissolved in 15ml deionized water to obtain solution A. Solution A was added to the deionized water in which Ti-SBA-15 was dispersed and stirred for 15min. The mass ratio of Ti-SBA-15 to Mg salt was 1:1.

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

[0060] The third step is to separate the solid by centrifugation, wash the precipitate with 100 ml of deionized water until it is neutral, dehydrate and dry the solid with a single-row tube, grind it into fine powder, and calcine it at 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 comprises the following steps:

[0063] Dissolve 10g P123 in 232ml hydrochloric acid solution with pH<1, stir for two hours at 35°C until completely dissolved, add 10g tetraethyl silicate (TEOS) and 1.09g tetraethyl titanate (TEOT) dropwise with a constant pressure dropping funnel while stirring, so that the Si / Ti molar ratio is 10:1, stir for 30 minutes, let the reaction stand at 35°C for 24h, crystallize at 80°C for 24h, separate the solid, and heat from 30°C to 550°C at 10°C per minute in an oven-type muffle furnace, calcine at 550°C for 5h to remove the template to obtain Ti-SBA-15 (Si / Ti=10 / 1).

[0064] In the first step, 1g Ti-SBA-15 was dispersed in 25ml deionized water and stirred for 30min. Magnesium nitrate hexahydrate (2mmol, 0.5128g) and zinc nitrate hexahydrate (2mmol, 0.595g) were fully dissolved in 15ml deionized water to obtain solution A. Solution A was added to the deionized water in which Ti-SBA-15 was dispersed and stirred for 15min. The mass ratio of Ti-SBA-15 to Mg salt was 2:1.

[0065] In the second step, at a temperature of 25°C, slowly and dropwise add ammonia water to the solution obtained in the first step under vigorous stirring, monitor the pH value, and stop adding ammonia water when the pH value reaches 10, and continue stirring at a temperature of 25°C for 24 hours.

[0066] The third step is to separate the solid by centrifugation, wash the precipitate with 100 ml of deionized water until it is neutral, dehydrate and dry the solid with a single-row tube, grind it into fine powder, and calcine it 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 comprises the following steps:

[0069] Dissolve 10g P123 in 232ml hydrochloric acid solution with pH<1, stir for two hours at 35°C until completely dissolved, add 10g tetraethyl silicate (TEOS) and 1.09g tetraethyl titanate (TEOT) dropwise with a constant pressure dropping funnel while stirring, so that the Si / Ti molar ratio is 10:1, stir for 30 minutes, let the reaction stand at 35°C for 24h, crystallize at 80°C for 24h, separate the solid, and heat from 30°C to 550°C at 10°C per minute in an oven-type muffle furnace, calcine at 550°C for 5h to remove the template to obtain Ti-SBA-15 (Si / Ti=10 / 1).

[0070] In the first step, 1g Ti-SBA-15 was dispersed in 25ml deionized water and stirred for 30min. Magnesium nitrate hexahydrate (2mmol, 0.5128g) and zinc nitrate hexahydrate (4mmol, 1.19g) were fully dissolved in 15ml deionized water to obtain solution A. Solution A was added to the deionized water in which Ti-SBA-15 was dispersed and stirred for 15min. The mass ratio of Ti-SBA-15 to Mg salt was 2:1.

[0071] In the second step, at a temperature of 25°C, slowly and dropwise add ammonia water to the solution obtained in the first step under vigorous stirring, monitor the pH value, and stop adding ammonia water when the pH value reaches 10, and continue stirring at a temperature of 25°C for 24 hours.

[0072] The third step is to separate the solid by centrifugation, wash the precipitate with 100 ml of deionized water until it is neutral, dehydrate and dry the solid with a single-row tube, grind it into fine powder, and calcine it at 550 ° C for 5 h 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 comprises the following steps:

[0075] Dissolve 10g P123 in 232ml hydrochloric acid solution with pH<1, stir for two hours at 35°C until completely dissolved, add 10g tetraethyl silicate (TEOS) and 1.09g tetraethyl titanate (TEOT) dropwise with a constant pressure dropping funnel while stirring, so that the Si / Ti molar ratio is 10:1, stir for 30 minutes, let the reaction stand at 35°C for 24h, crystallize at 80°C for 24h, separate the solid, and heat from 30°C to 550°C at 10°C per minute in an oven-type muffle furnace, calcine at 550°C for 5h to remove the template to obtain Ti-SBA-15 (Si / Ti=10 / 1).

[0076] In the first step, 1g Ti-SBA-15 was dispersed in 25ml deionized water and stirred for 30min. Magnesium nitrate hexahydrate (4.5mmol, 1.1538g) and zinc nitrate hexahydrate (1.5mmol, 0.4463g) were fully dissolved in 15ml deionized water to obtain solution A. Solution A was added to the deionized water in which Ti-SBA-15 was dispersed and stirred for 15min. The mass ratio of Ti-SBA-15 to Mg salt was 1:1.15.

[0077] In the second step, at a temperature of 25°C, slowly and dropwise add ammonia water to the solution obtained in the first step under vigorous stirring, monitor the pH value, and stop adding ammonia water when the pH value reaches 10, and continue stirring at a temperature of 25°C for 24 hours.

[0078] The third step is to separate the solid by centrifugation, wash the precipitate with 100 ml of deionized water until it is neutral, dehydrate and dry the solid with a single-row tube, grind it into fine powder, and calcine it 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 comprises the following steps:

[0081] Dissolve 10g P123 in 232ml hydrochloric acid solution with pH<1, stir for two hours at 35°C until completely dissolved, add 10g tetraethyl silicate (TEOS) and 1.09g tetraethyl titanate (TEOT) dropwise with a constant pressure dropping funnel while stirring, so that the Si / Ti molar ratio is 10:1, stir for 30 minutes, let the reaction stand at 35°C for 24h, crystallize at 80°C for 24h, separate the solid, and heat from 30°C to 550°C at 10°C per minute in an oven-type muffle furnace, calcine at 550°C for 5h to remove the template to obtain Ti-SBA-15 (Si / Ti=10 / 1).

[0082] In the first step, 1g Ti-SBA-15 was dispersed in 25ml deionized water and stirred for 30min. Magnesium nitrate hexahydrate (3mmol, 0.7692g) and zinc nitrate hexahydrate (1mmol, 0.2975g) were fully dissolved in 15ml deionized water to obtain solution A. Solution A was added to the deionized water in which Ti-SBA-15 was dispersed and stirred for 15min. The mass ratio of Ti-SBA-15 to Mg salt was 10:7.

[0083] In the second step, at a temperature of 25°C, slowly and dropwise add ammonia water to the solution obtained in the first step under vigorous stirring, monitor the pH value, and stop adding ammonia water when the pH value reaches 10, and continue stirring at a temperature of 25°C for 24 hours.

[0084] The third step is to separate the solid by centrifugation, wash the precipitate with 100 ml of deionized water until it is neutral, dehydrate and dry the solid with a single-row tube, grind it into fine powder, and calcine it at 550 ° C for 5 h 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 comprises the following steps:

[0087] Dissolve 10g P123 in 232ml hydrochloric acid solution with pH<1, stir for two hours at 35°C until completely dissolved, add 10g tetraethyl silicate (TEOS) and 1.09g tetraethyl titanate (TEOT) dropwise with a constant pressure dropping funnel while stirring, so that the Si / Ti molar ratio is 10:1, stir for 30 minutes, let the reaction stand at 35°C for 24h, crystallize at 80°C for 24h, separate the solid, and heat from 30°C to 550°C at 10°C per minute in an oven-type muffle furnace, calcine at 550°C for 5h to remove the template to obtain Ti-SBA-15 (Si / Ti=10 / 1).

[0088] In the first step, 1g Ti-SBA-15 was dispersed in 25ml deionized water and stirred for 30min. Magnesium nitrate hexahydrate (1.5mmol, 0.3846g) and zinc nitrate hexahydrate (0.5mmol, 0.1487g) were fully dissolved in 15ml deionized water to obtain solution A. Solution A was added to the deionized water in which Ti-SBA-15 was dispersed and stirred for 15min. The mass ratio of Ti-SBA-15 to Mg salt was 1:0.38.

[0089] In the second step, at a temperature of 25°C, slowly and dropwise add ammonia water to the solution obtained in the first step under vigorous stirring, monitor the pH value, and stop adding ammonia water when the pH value reaches 10, and continue stirring at a temperature of 25°C for 24 hours.

[0090] The third step is to separate the solid by centrifugation, wash the precipitate with 100 ml of deionized water until it is neutral, dehydrate and dry the solid with a single-row tube, grind it into fine powder, and calcine it at 550 ° C for 5 h 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 (Si / Ti=20 / 1) comprises the following steps:

[0093] Dissolve 10g P123 in 232ml hydrochloric acid solution with pH<1, stir for two hours at 35°C until completely dissolved, add 10g tetraethyl silicate (TEOS) and 0.545g tetraethyl titanate (TEOT) dropwise with a constant pressure dropping funnel while stirring, so that the Si / Ti molar ratio is 20:1, stir for 30 minutes, let the reaction stand at 35°C for 24h, crystallize at 80°C for 24h, separate the solid, and heat from 30°C to 550°C at 10°C per minute in an oven-type muffle furnace, calcine at 550°C for 5h to remove the template to obtain Ti-SBA-15 (Si / Ti=20 / 1).

[0094] In the first step, 1g Ti-SBA-15 (Si / Ti=20 / 1) was dispersed in 25ml deionized water and stirred for 30min. Magnesium nitrate hexahydrate (4.5mmol, 1.1538g) and zinc nitrate hexahydrate (1.5mmol, 0.4463g) were fully dissolved in 15ml deionized water to obtain solution A. Solution A was added to the deionized water in which Ti-SBA-15 was dispersed and stirred for 15min. The mass ratio of Ti-SBA-15 (Si / Ti=20 / 1) to Mg salt was 1:1.15.

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

[0096] The third step is to separate the solid by centrifugation, wash the precipitate with 100 ml of deionized water until it is neutral, dehydrate and dry the solid with a single-row tube, grind it into fine powder, and calcine it at 550 ° C for 5 h to obtain the catalyst MgZn (3) -Ti-SBA-15 (0.3) .

[0097] Example 10

[0098] MgZn (3) -Ti-SBA-15 (0.3) The preparation method of (Si / Ti=40 / 1) comprises the following steps:

[0099] Dissolve 10g P123 in 232ml hydrochloric acid solution with pH<1, stir for two hours at 35°C until completely dissolved, add 10g tetraethyl silicate (TEOS) and 0.2725g tetraethyl titanate (TEOT) dropwise with a constant pressure dropping funnel while stirring, so that the Si / Ti molar ratio is 40:1, stir for 30 minutes, let the reaction stand at 35°C for 24h, crystallize at 80°C for 24h, separate the solid, and heat from 30°C to 550°C at 10°C per minute in an oven-type muffle furnace, calcine at 550°C for 5h to remove the template to obtain Ti-SBA-15 (Si / Ti=40 / 1).

[0100] In the first step, 1 g of Ti-SBA-15 (Si / Ti = 40 / 1) was dispersed in 25 ml of deionized water and stirred for 30 min. Magnesium nitrate hexahydrate (4.5 mmol, 1.1538 g) and zinc nitrate hexahydrate (1.5 mmol, 0.4463 g) were fully dissolved in 15 ml of deionized water to obtain solution A. Solution A was added to the deionized water in which Ti-SBA-15 was dispersed and stirred for 15 min. The mass ratio of Ti-SBA-15 (Si / Ti = 40 / 1) to Mg salt was 1:1.15.

[0101] In the second step, at a temperature of 25°C, slowly and dropwise add ammonia water to the solution obtained in the first step under vigorous stirring, monitor the pH value, and stop adding ammonia water when the pH value reaches 10, and continue stirring at a temperature of 25°C for 24 hours.

[0102] The third step is to separate the solid by centrifugation, wash the precipitate with 100 ml of deionized water until it is neutral, dehydrate and dry the solid with a single-row tube, grind it into fine powder, and calcine it at 550 ° C for 5 h to obtain the catalyst MgZn (3) -Ti-SBA-15 (0.3) .

[0103] The infrared spectrum of the catalyst prepared in the example is shown in Figure 1 , Figure 2 , Figure 3 As shown, Figure 1 It is the infrared spectra of the catalysts of Examples 6, 7 and 8. Figure 2 It is the infrared spectra of the catalysts of Examples 1, 3, 4 and 5. Figure 3 The infrared spectra of the catalysts of Examples 9 and 10 are shown in Figure 1. After the addition of Ti and the loading of Mg and Zn, the infrared spectra at 960 cm -1 The corresponding Si-OH vibration peak intensity is significantly reduced or disappears, indicating the combination of Mg, Zn, Ti and Si-OH. Figure 4 , Figure 5 As shown, Figure 4 Examples 6, 7, and 8 are Ti-SBA-15 (a), MgZn3-TiSBA-15 0.1 (b), MgZn3-TiSBA-15 0.2 (c), MgZn3-TiSBA-15 0.3 (d) Schematic diagram of the scanning electron microscope image. Figure 5 It is Ti-SBA-15 in Examples 8 and 9. (Si / Ti＝20) (a) Ti-SBA-15 (Si / Ti＝40) (b), MgZn3-Ti-SBA-15 (Si / Ti＝20) (c), MgZn3-Ti-SBA-15 (Si / Ti＝40) (d) Schematic diagram of the scanning electron microscope image. As can be seen from the figure, the catalyst has a spherical appearance. The Ti-SBA-15 microspheres without Mg and Zn loading have a smooth spherical surface. After loading, many irregular particles appear on the surface of the microspheres. These particles are MgO and ZnO formed on the surface, indicating that Mg and Zn are successfully loaded on the carrier surface.

[0104] Application Example 1

[0105] Evaluation reaction of the catalytic effect of the catalyst prepared in the embodiment of the present invention on the oxidation of cyclohexanone with hydrogen peroxide

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

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

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

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

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

[0111] The catalysts prepared in Examples 1 to 10 were used to catalyze the oxidation of cyclohexanone with hydrogen peroxide to prepare ε-caprolactone. The reaction results were all data after the reaction reached a steady state. The results are shown in Table 1:

[0112] Table 1 Catalytic effect of catalysts with different MgZn metal ratios

[0113] catalyst Conversion rate Selectivity Yield Example 1 <![CDATA[MgZn4-Ti-SBA-15 (0.49) ]]> 68.47％ 60.98％ 41.75％ Example 2 <![CDATA[MgZn3-Ti-SBA-15 (0.41) ]]> 84.49％ 96.73％ 81.73％ Example 3 <![CDATA[MgZn2-Ti-SBA-15 (0.32) ]]> 69.19％ 69.26％ 47.92％ Example 4 <![CDATA[MgZn1-Ti-SBA-15 (0.24) ]]> 71.41％ 60.50％ 43.20％ Example 5 <![CDATA[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 rate Selectivity Yield Example 2 <![CDATA[MgZn3-Ti-SBA-15 (0.41) ]]> 84.49％ 96.73％ 81.73％ Example 6 <![CDATA[MgZn3-Ti-SBA-15 (0.3) ]]> 90.93％ 92.55％ 84.15％ Example 7 <![CDATA[MgZn3-Ti-SBA-15 (0.2) ]]> 82.39％ 97.12％ 80.01％ Example 8 <![CDATA[MgZn3-Ti-SBA-15 (0.1) ]]> 80.47％ 90.55％ 72.87％

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

[0117] catalyst Conversion rate Selectivity Yield Example 6 <![CDATA[MgZn3-Ti-SBA-15 (0.3) If / If=10 / 1]]> 90.93％ 92.55％ 84.15％ Example 9 <![CDATA[MgZn3-Ti-SBA-15 (0.3) If / If=20 / 1]]> 81.26％ 91.81％ 74.60％ Example 10 <![CDATA[MgZn3-Ti-SBA-15 (0.3) If / If=40 / 1]]> 77.09％ 91.96％ 70.89％

[0118] In Tables 1 to 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] It can be seen from the results of Table 1, Table 2 and Table 3 that by adjusting the ratio of the two metals in the catalyst, the ratio of the carrier to the active species, and the silicon-titanium ratio in the carrier, a higher conversion rate and selectivity can be obtained in the reaction of cyclohexanone oxidizing with hydrogen peroxide to prepare ε-caprolactone. When the Mg / Zn molar ratio is 0.5, the conversion rate of cyclohexanone is as high as 85.72%, but the selectivity is low, only 63.47%. When the Mg / Zn molar ratio is 3, under different loading ratios and carrier silicon-titanium ratios, the highest conversion rate of cyclohexanone reaches 90.93%, and the selectivity is 92.55% (when the mass ratio of MgO, ZnO to the carrier is 0.3 and the carrier silicon-titanium ratio is 10). The catalyst prepared in the embodiment of the present invention is an efficient heterogeneous catalyst for preparing ε-caprolactone from cyclohexanone in a hydrogen peroxide system.

[0120] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

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

6.

2. A method for preparing the catalyst according to claim 1, characterized in that: The following steps are involved: The first step is to disperse Ti-SBA-15 in deionized water to a concentration of 0.01 to 1 g / ml and stir for 10 to 60 minutes; Dissolve Mg salt and Zn salt in deionized water at a molar ratio of 0.5 to 4:1 to obtain solution A; The mass ratio of Ti-SBA-15 to Mg salt is 0.5 to 4:1; Add solution A to the deionized water in which Ti-SBA-15 is dispersed and stir for 10 to 60 minutes; Step 2: Add an alkaline reagent dropwise to the solution obtained in Step 1 at a temperature of 20 to 30°C, stop adding the alkaline reagent dropwise when the pH value is 9 to 11, and continue stirring at a temperature of 20 to 30°C for 1 to 24 hours; The third step is to separate the solid by centrifugation, wash the precipitate with deionized water until it is neutral, dehydrate and dry the solid, grind it into fine powder, and calcine it to obtain the catalyst.

3. The method for preparing the catalyst according to claim 2, characterized in that: The Mg salt is selected from magnesium nitrate hexahydrate and magnesium chloride.

4. The method for preparing the catalyst according to claim 2, characterized in that: The Zn salt is selected from zinc nitrate hexahydrate and zinc chloride.

5. The method for preparing the catalyst according to claim 2, characterized in that: The alkaline agent is selected from sodium hydroxide and ammonia water.

6. The method for preparing the catalyst according to claim 2, characterized in that: The calcination temperature is 500-600° C. and the calcination time is 1-8 hours.

7. The method for preparing a catalyst according to claim 2, characterized in that: The preparation method of Ti-SBA-15 comprises the following steps: P123 is dissolved in a hydrochloric acid solution with a pH value less than 1 to make the concentration of 0.01 to 1 g / ml, and stirred for 1 to 4 hours at a temperature of 20 to 40°C. A mixed solution of tetraethyl silicate and a titanium-containing compound with a molar ratio of 10 to 100:1 is added dropwise under stirring to make the molar ratio of Si to Ti 10 to 100:1, and stirred for 10 to 60 minutes. The reaction is allowed to stand for 1 to 24 hours at a temperature of 20 to 40°C, and crystallized for 1 to 24 hours at a temperature of 70 to 90°C, and the solid is separated and calcined to obtain Ti-SBA-15. The mass ratio of MgO, ZnO and Ti-SBA-15 in the catalyst is 0.05 to 0.6; The titanium-containing compound is selected from tetraethyl titanate, tetrabutyl titanate, and titanium tetraisopropoxide.

8. The method for preparing the catalyst according to claim 7, characterized in that: The calcination temperature is 500-600° C., the time is 1-8 hours, the heating rate is 10° C. per minute, and the temperature is increased from 30° C.

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

Images