Preparation method of modified titanium silicon catalyst and its application in catalyzing olefin epoxidation reaction

Abstract

The present invention discloses a method for preparing a modified titanium silicon catalyst and its application in catalyzing the epoxidation of olefins. The present invention first modifies Ti-TUD-1 with an alkaline solution, then performs a secondary modification on it with a fluoride-containing solution, and finally obtains a modified titanium silicon catalyst by silanization treatment. The modification measures of the present invention can increase the pore size of the catalyst, improve the hydrophobicity of the catalyst surface, and reduce the contact restriction between the reaction substrate and the catalytic active center; more tetracoordinate titanium is produced, thereby improving the catalytic activity. The catalyst prepared by this method further improves the catalytic performance in the epoxidation reaction of olefins with alkyl hydrogen peroxide solution, and has good industrial application prospects.

Description

Technical Field

[0001] The present invention relates to a method for preparing a titanium silicon catalyst, in particular to a method for preparing a modified titanium silicon catalyst and application of the catalyst in catalyzing olefin epoxidation reactions. Background Art

[0002] Epoxides, as important intermediates in the synthesis of fine chemicals and pharmaceuticals, are widely used in pharmaceuticals, surfactants, polymers, and other related industries. They are a particularly important and versatile product. Currently, the main processes for preparing epoxy compounds include the chlorohydrin method, direct oxidation with hydrogen peroxide, and co-oxidation. The co-oxidation method uses alkyl hydroperoxide as an oxygen source to epoxidize olefins. This process effectively avoids the equipment corrosion caused by the chlorohydrin method, is economical and environmentally friendly, and is safer than the direct oxidation with hydrogen peroxide. Its share of production capacity has also been gradually increasing, and its development prospects are promising.

[0003] For epoxidation reactions, the quality of the catalyst is one of the key factors affecting the reaction effect. In the epoxidation process, catalysts can be roughly divided into homogeneous catalysts and heterogeneous catalysts. The amount of homogeneous catalyst used is small, the degree of mixing with the reaction solution is high, and it has high catalytic activity, but it is not easy to separate and recycle, which affects the quality of the product, thereby generating additional costs. Heterogeneous catalysts can effectively avoid this deficiency and have relatively good catalytic activity during the catalytic reaction. Among them, titanium-based catalysts are widely studied and have high catalytic activity and selectivity in the epoxidation reaction of olefins and organic peroxides. Titanium silicate molecular sieve, as one of the heterogeneous catalysts, has good catalytic activity for the selective oxidation of olefins and is often used as a catalyst for the selective oxidation of olefins to prepare epoxides.

[0004] Titanium-containing catalysts include microporous catalysts such as TS-1, Ti-Beta, Ti-MOR, and Ti-MWW, as well as mesoporous catalysts such as Ti-MCM-41, Ti-SBA-15, Ti-HMS, and composite pore catalysts. TS-1 is the most extensively studied and thoroughly studied of these microporous catalysts, with its synthesis method disclosed in U.S. Patent No. 4,410,501. However, TS-1 suffers from harsh preparation conditions, long cycles, high costs, and a small pore size. This results in poor catalytic performance in the epoxidation of macromolecular olefins with alkyl hydroperoxides as the oxygen source, limiting its application.

[0005] In 1920, the American company Mobil Corporation developed the M41S series of mesoporous materials, primarily MCM-41, marking a new chapter in the development of mesoporous materials. Mesoporous titanium silicate catalysts possess large pore size, pore volume, and specific surface area. These catalysts reduce the diffusion resistance between pores during catalytic macromolecular reactions, allowing reactant molecules to diffuse more easily into the pores and contact the catalytic active sites, while products also diffuse more easily out of the pores. This makes them suitable for diffusion-limited macromolecular reactions. J.C. Jansen, for the first time, used a non-surfactant as a template to create the foamy, amorphous, three-dimensional mesoporous material TUD-1. Compared to other mesoporous materials (such as SBA-15), TUD-1 offers advantages in terms of low preparation cost, adjustable pore size, high specific surface area, high hydrothermal stability, and excellent mechanical stability. The center of the TUD-1 mesoporous material is a silicon-oxygen tetrahedral skeleton, which has low activity in many reactions, so it is necessary to create active centers in the skeleton. Currently, different M-TUD-1 catalysts (M=Fe, Co, Ni, Ti, Cr) have been prepared by a one-step synthesis method. Among them, Ti-TUD-1 is applied to the catalytic olefin epoxidation system and has high catalytic activity.

[0006] Titanium-silicon catalysts used in olefin epoxidation reactions primarily exist in three forms: framework tetracoordinated titanium species, highly coordinated titanium species, amorphous titanium species, and non-framework titanium species. The coordination state of the titanium species directly influences the catalyst's performance. The presence of non-framework titanium can cover some active sites, blocking pores and restricting reactant diffusion. Framework highly coordinated titanium species and amorphous titanium species (Ti-O-Ti) possess strong acidity, which can lead to inefficient decomposition of some oxygen sources and ring opening of the epoxide product, thereby reducing catalytic activity. Modifying the coordination state of the titanium species to create more active sites, increase the catalyst's hydrophobicity, and reduce its surface acidity are currently hot topics of research. Common modification methods include salt modification, acid modification, base modification, fluorination modification, and silanization. Base modification can etch the molecular sieve, creating cavities within the zeolite that facilitate substrate diffusion and improve the catalyst's catalytic activity. Chinese invention CN102502690A mentions that the use of inorganic bases and organic bases to modify TS-1 respectively can simultaneously improve the catalytic performance of TS-1 in gas-phase and liquid-phase propylene epoxidation reactions. Chinese invention CN103539149A uses an organic alkaline solution to modify titanium silicate molecular sieves. This modification process reduces or even eliminates non-framework titanium, and the catalytic epoxidation activity of the modified molecular sieve is improved. Chinese invention CN1358570A mentions that the use of inorganic bases and organic bases to modify conventionally synthesized TS-2 by high-temperature secondary crystallization. After modification, the TS-2 molecular sieve has a hollow structure or a larger pore system, which is conducive to molecular diffusion in the reaction and improves the catalytic performance of the catalyst. Chinese invention CN101591024A mentions that the use of fluorine-containing acidic compounds to impregnate different titanium silicate molecular sieves effectively removes non-framework titanium, adjusts the hydrophilicity and hydrophobicity of the molecular sieve surface, and significantly improves the catalytic performance of the molecular sieve. The present invention performs post-treatment modification on Ti-TUD-1 through alkali modification, secondary fluorination modification and liquid phase silanization in sequence, and applies the modified catalyst to the reaction system of olefin and alkyl hydroperoxide epoxidation, hoping to further improve the utilization rate of oxygen source and the yield of epoxy product. Summary of the Invention

[0007] The present invention provides a method for preparing a modified titanium silicon catalyst, and uses the catalyst for catalyzing olefin epoxidation reactions. The preparation process of the present invention comprises four steps: in-situ synthesis of a Ti-TUD-1 mesoporous material, alkali modification, fluorine modification, and liquid-phase silanization. Ti-TUD-1 is first modified by treating it with an alkaline solution, then dissolved in a fluorine-containing modifying solution for a secondary modification treatment, and finally subjected to silanization treatment to obtain a modified titanium silicon catalyst. The resulting catalyst is used in the epoxidation reaction of olefins with an alkyl hydroperoxide solution, and its catalytic effect is improved compared to that of the unmodified catalyst.

[0008] The object of the present invention is achieved in the following manner:

[0009] A method for preparing a modified mesoporous titanium silicalite catalyst comprises the following steps performed in sequence:

[0010] (1) The in situ synthesized Ti-TUD-1 mesoporous material, the alkaline compound and water are uniformly mixed to obtain a mixed solution A;

[0011] (2) aging, washing, and drying the mixed solution A obtained in step (1) to obtain powder a;

[0012] (3) uniformly mixing the powder a obtained in step (2), the fluorine-containing compound, and the solvent to obtain a mixed solution B;

[0013] (4) aging, washing, drying, and calcining the mixed solution B obtained in step (3) to obtain powder b;

[0014] (5) The powder b obtained in step (4) is subjected to silanization treatment to obtain a modified titanium silicon catalyst.

[0015] Furthermore, in step (1), the alkaline compound is one or more of sodium hydroxide, sodium carbonate, ammonia water, ethyl acetate, diethanolamine, triethanolamine, tetraethylammonium hydroxide, tetramethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide, and the amount ratio of Ti-TUD-1, alkaline compound and H2O is 100 g: (0.01~2) mol: (5~250) mol.

[0016] Furthermore, in step (2), the aging temperature is 10-65°C, and the time is 12-72 hours; the drying temperature is 65-150°C, and the time is 3-48 hours.

[0017] Furthermore, in step (3), the fluorine-containing compound is one or more of sodium fluoride, hexafluorotitanic acid, ammonium fluoride, and ammonium fluorosilicate, the solvent is one or more of nitric acid, methanol, water, and cyclohexane, and the mass ratio of Ti-TUD-1, methanol, and ammonium fluoride is 1:(10~120):(0.05~20).

[0018] Furthermore, in step (4), the aging temperature is 10-65°C, and the time is 12-72 hours; the drying temperature is 65-150°C, and the time is 3-48 hours; and the calcination temperature is 400-800°C, and the time is 2-18 hours.

[0019] Furthermore, the method for synthesizing Ti-TUD-1 mesoporous material refers to the in situ synthesis method in the reference Preparation of TitaniumModified TUD-1 Catalysts for Propylene Epoxidation (https: / / doi.org / 10.1007 / s10562-017-2030-8): ethyl orthosilicate, triethanolamine, tetraethylammonium hydroxide, butyl titanate, and water are mixed and stirred at room temperature to form a homogeneous solution, and then aged, dried, heat treated, and calcined to obtain Ti-TUD-1 mesoporous material.

[0020] The modified catalyst obtained by the above preparation method is used in the co-oxidation reaction of olefins and alkyl hydroperoxide solution in the presence of a solvent, with a reaction temperature of 70-180°C, a reaction time of 0.5-5 hours, a reaction pressure of 0.1-4 MPa, a mass fraction of the catalyst in the reaction solution of 0.5%-6%, a mass fraction of the alkyl hydroperoxide in the solvent of 5%-40%, and a molar ratio of olefin to alkyl hydroperoxide of (0.5-30):1.

[0021] Furthermore, the alkyl hydroperoxide is mixed with a solvent and added to the catalytic reaction in the form of a solution, wherein the alkyl hydroperoxide is cumene hydroperoxide, cyclohexyl hydroperoxide, tert-butyl hydroperoxide or ethylbenzene hydroperoxide; the solvent is cumene, cyclohexane, tert-butyl alcohol or ethylbenzene; and the olefin is C3~C 10 of chain or cyclic alkenes.

[0022] The alkali modification, fluorine modification and liquid phase silanization in the above preparation method must be carried out in sequence. If the sequence is adjusted, the modification effect will be worse, or no modification effect will be produced, and the modification may even reduce the reaction effect.

[0023] The beneficial effects of the present invention are as follows:

[0024] (1) The present invention modifies the mesoporous Ti-TUD-1 material, which has a high specific surface area and hydrothermal stability, and an adjustable pore size. At the same time, the synthesis of the material is relatively simple and low-cost. It has high activity in catalyzing the reaction of olefin molecules with different kinetic diameters and alkyl hydroperoxides, and has good prospects for industrial application.

[0025] (2) The present invention adopts a multi-step modification method to post-treat the Ti-TUD-1 mesoporous material. Since Ti-TUD-1 is an amorphous material, its amorphous mesoporous structure is basically not destroyed after modification, and the pore size is increased, which reduces the diffusion restriction of the catalyst pores on the macromolecular reaction substrate and improves the utilization rate of the oxygen source.

[0026] (3) Before hydrophobicity modification, the modified catalyst of the present invention was found to have a higher hydrophobicity than Ti-TUD-1. After silanization treatment, the hydrophobicity of the catalyst surface was further increased. At the same time, the organic silane groups on its surface also made it easier for olefins and alkyl hydroperoxide molecules to be approached and adsorbed, thereby improving the catalytic performance.

[0027] (4) Compared with the unmodified Ti-TUD-1, the catalytic performance of F-Ti-TUD-1(S) prepared by the present invention is improved. For example, when applied to the reaction system of propylene and cyclohexyl hydroperoxide, the conversion rate of cyclohexyl hydroperoxide is increased by 8% to 9%, and the selectivity of epoxy products is increased by 10% to 12%.

[0028] In view of the above four points, the catalyst prepared by the modification method provided by the present invention has relatively simple preparation steps and low preparation cost. In the catalytic epoxidation reaction of olefins with alkyl hydroperoxide solution, the catalytic performance is further improved, and it has good industrial application prospects. DETAILED DESCRIPTION

[0029] The present invention is further described below with reference to specific examples. The following examples are merely illustrative and the present invention is not limited thereto.

[0030] Example 1

[0031] 1) Preparation of Ti-TUD-1 mesoporous material: 35.12 g of tetraethyl silicate was added dropwise to 29.69 g of tetraethylammonium hydroxide under stirring, and the mixture was stirred. 1.19 g of tetrabutyl titanate was added dropwise to 25.06 g of triethanolamine under stirring, and the mixture was stirred. The two mixtures were combined and rapidly stirred for 1 hour. 11.03 g of water was then added and stirred for 0.5 hour to form a homogeneous solution of Ti-TUD-1. The homogeneous solution was then aged at room temperature in the dark for 48 hours, dried in a drying oven at 100°C for 24 hours, ground, and heat treated at 180°C in a homogeneous reactor for 8 hours. Finally, it was calcined at 600°C in a muffle furnace for 10 hours to obtain the Ti-TUD-1 mesoporous material.

[0032] 2) Alkali modification: Weigh 1.20 g of tetraethylammonium hydroxide and dissolve it in 72.0 g of water, stir and mix thoroughly. Then dissolve 4.0 g of Ti-TUD-1 in the above solution and stir and mix thoroughly. Aging at room temperature in the dark for 48 h; filtering and washing; and drying at 100°C for 12 h to obtain Ti-TUD-1(a).

[0033] 3) Fluorine modification: Dissolve 0.32 g of ammonium fluoride in 40.0 g of methanol solution and mix well. Then dissolve Ti-TUD-1(a) in the above solution and mix well. Aging at room temperature for 48 h; filtration and washing; drying at 100 °C for 12 h; calcination at 600 °C for 4 h to obtain F-Ti-TUD-1(b).

[0034] 4) Silanization: Disperse 3.00 g of the above-mentioned F-Ti-TUD-1(b) in 50.00 g of toluene. Add 1.5 g of hexamethyldisilazane (HMDS) to the suspension and reflux with stirring at 110°C for 5 h. After cooling, filter the mixture, wash three times with 50 mL of toluene, and finally dry it in a vacuum oven at 110°C for 12 h to obtain the modified catalyst F-Ti-TUD-1(c).

[0035] Example 2

[0036] According to the operating process of Example 1, the difference from Example 1 is:

[0037] 1) In the alkaline modification step, aging was performed at 25°C for 24 h; filtration and washing were performed; and drying was performed at 110°C for 10 h to obtain F-Ti-TUD-1(d).

[0038] 2) In the fluorine modification step, aging was performed at 25°C for 12 h; filtration and washing were performed; drying was performed at 80°C for 10 h; and calcination was performed at 500°C for 4 h to obtain F-Ti-TUD-1(e).

[0039] 3) The same silanization treatment was performed to obtain F-Ti-TUD-1(f).

[0040] Example 3

[0041] The preparation of Ti-TUD-1 mesoporous material is the same as that in Example 1, and the modification steps are as follows.

[0042] 1) Alkali modification: Weigh 0.72 g of tetraethylammonium hydroxide and dissolve it in 72.0 g of water, stir and mix thoroughly. Then dissolve 4.0 g of Ti-TUD-1 in the above solution and stir and mix thoroughly. Aging at room temperature in the dark for 12 h was performed. Filter and wash the product, and dry it at 150°C for 8 h to obtain Ti-TUD-1 (g).

[0043] 2) Fluorine modification: Dissolve 0.19 g of ammonium fluoride in 60.0 g of methanol solution and mix well. Then dissolve Ti-TUD-1(g) in the above solution and mix well. Aging at room temperature for 24 h; filtration and washing; drying at 120°C for 6 h; and calcination at 550°C for 4 h to obtain F-Ti-TUD-1(h).

[0044] 3) Silanization: Disperse 2.00 g of the above-mentioned F-Ti-TUD-1(h) in 50.00 g of toluene. Add 1.03 g of hexamethyldisilazane (HMDS) to the suspension and reflux with stirring at 100°C for 3 h. After cooling, filter and wash three times with 50 mL of toluene. Finally, dry in a vacuum oven at 110°C for 12 h to obtain the modified catalyst F-Ti-TUD-1(i).

[0045] The cyclohexane oxidation liquid used in the following Examples 4 to 7 and Comparative Examples 1 to 3 comprises the following components in percentage by mass: 69.53% cyclohexane, 14.77% cyclohexyl hydroperoxide, 5.70% cyclohexanone, 2.00% cyclohexanol, 1.46% acid, and 6.54% ester.

[0046] Example 4

[0047] The catalyst prepared in Example 1 was used in the epoxidation of propylene with cyclohexyl hydroperoxide solution in a batch reactor. A rotor was added to the reactor, followed by 0.8 g of catalyst and 20.02 g of cyclohexane oxidizing solution. After sealing the reactor, 12.5 g of liquid propylene was added via a horizontal flow pump. The reaction was carried out at 90°C under its own pressure for 2 hours. After the reaction, the reactor was cooled to below 10°C in an ice-water bath. The reactor outlet valve was opened, and the released gas was absorbed by cyclohexane and then vented. The reaction solution was mixed with the cyclohexane tail aspirate for analysis.

[0048] Example 5

[0049] The catalyst prepared in Example 2 was used in the epoxidation of propylene with cyclohexyl hydroperoxide solution under the same reaction conditions as in Example 4.

[0050] Example 6

[0051] The catalyst prepared in Example 3 was used in the epoxidation of propylene with cyclohexyl hydroperoxide solution. The reaction conditions were the same as those in Example 4.

[0052] The iodine titration method was used to analyze the content of cyclohexyl hydroperoxide before and after the reaction. The gas chromatography internal standard method was used to analyze the content of propylene oxide, cyclohexanol, and cyclohexanone generated by the reaction. The calculation results are shown in Table 1.

[0053] Table 1 Epoxidation reaction results catalyzed by different catalysts

[0054]

[0055] Example 7

[0056] The catalyst prepared in Example 1 was used for the epoxidation of propylene and cumene hydrogen peroxide solution in an intermittent reactor. A rotor, 0.59g of catalyst, and 20.01g of 15.0wt% cumene hydrogen peroxide solution were added to the reactor in sequence. The reactor was sealed for leak detection and then filled with 9.1g of liquid propylene. The reactor was placed in an oil bath for reaction and reacted at 90°C for 2h under its own pressure. After the reaction was completed, the reactor was placed in ice water and cooled to below 10°C. Unreacted propylene was released through an exhaust valve and absorbed with cumene before being emptied. The reaction solution was mixed with the cumene tail liquid for detection and analysis.

[0057] Example 8

[0058] The catalyst prepared in Example 2 was used in the epoxidation of propylene with cumene hydroperoxide solution under the same reaction conditions as in Example 8.

[0059] Example 9

[0060] The catalyst prepared in Example 3 was used in the epoxidation of propylene with cumene hydroperoxide solution. The reaction conditions were the same as those in Example 8.

[0061] The iodine titration method was used to analyze the content of cumene hydroperoxide before and after the reaction, and the gas chromatography internal standard method was used to analyze the content of propylene oxide generated by the reaction. The calculation results are shown in Table 2.

[0062] Table 2 Epoxidation results of different catalysts

[0063]

[0064] Comparative Example 1

[0065] The operating process of Example 1 is followed, but the difference from Example 1 is that the prepared Ti-TUD-1 mesoporous material is directly silanized without alkali modification and fluorine modification to obtain Ti-TUD-1(S).

[0066] The reaction conditions were the same as in Example 4, namely, unmodified Ti-TUD-1(S) catalyst was used in the epoxidation of propylene with cyclohexyl hydroperoxide solution in a batch reactor. 0.8 g of catalyst was added to the reactor, followed by 20.02 ml of cyclohexane oxidizing solution. After sealing the reactor, 12.5 g of liquid propylene was added and the reaction was carried out at 90°C under its own pressure for 2 h. After the reaction was completed, the reactor was placed in an ice-water bath and cooled to below 10°C. The reactor outlet valve was opened, and the released gas was absorbed by cyclohexane and then vented. The reaction solution was mixed with the cyclohexane tail aspirate for analysis and detection.

[0067] Comparative Example 2

[0068] Take 0.2g of ammonium fluoride and dissolve it in 80.0g of methanol solution and mix well. Then dissolve 4.0g of Ti-TUD-1 in the above solution and mix and stir; age at room temperature in the dark for 48h; filter and wash until neutral; dry at 100℃ for 24h; calcine at 600℃ for 4h, and finally perform silanization to obtain F-Ti-TUD-1(S).

[0069] The F-Ti-TUD-1(S) prepared by one-step fluorine modification was used in the epoxidation reaction of propylene with cyclohexyl hydroperoxide solution according to the reaction conditions of Comparative Example 1, and its various indicators were further tested and analyzed.

[0070] Comparative Example 3

[0071] Take 1.20g of tetraethylammonium hydroxide and dissolve it in 72.0g of water, stir and mix, then dissolve 4.0g of Ti-TUD-1 in the above solution, mix and stir; age in the dark at room temperature for 24h; filter and wash until neutral; dry at 100℃ for 12h; calcine at 600℃ for 4h, and finally silanize to obtain catalyst Ti-TUD-1(j).

[0072] The Ti-TUD-1(j) prepared by alkali modification was used in the epoxidation reaction of propylene with cyclohexyl hydroperoxide solution according to the reaction conditions of Comparative Example 1, and its various indicators were further tested and analyzed.

[0073] Comparative Example 4

[0074] The preparation of Ti-TUD-1 mesoporous material is the same as that in Example 1, and the modification steps are as follows.

[0075] 1) Fluorine modification: Dissolve 0.32g of ammonium fluoride in 40.0g of methanol solution and mix well. Then dissolve 4.0g of Ti-TUD-1(g) in the above solution and mix well. Aging at room temperature for 48h. Filter and wash until neutral. Dry at 100℃ for 12h to obtain F-Ti-TUD-1(k).

[0076] 2) Alkali modification: Weigh 1.20 g of tetraethylammonium hydroxide and dissolve it in 72.0 g of water, stir to mix, then dissolve Ti-TUD-1 in the above solution, mix and stir; age at room temperature in the dark for 48 h; filter and wash until neutral; dry at 100 ° C for 12 h; calcine at 600 ° C for 4 h to obtain F-Ti-TUD-1 (l).

[0077] 3) The silanization treatment was the same as in Example 1 to obtain F-Ti-TUD-1(m).

[0078] F-Ti-TUD-1(l) prepared by fluorine modification followed by alkali modification was used in the epoxidation reaction of propylene with cyclohexyl hydroperoxide solution according to the reaction conditions of Comparative Example 1, and its various indicators were further tested and analyzed.

[0079] The data of Comparative Examples 1-4 are shown in Table 3:

[0080] Table 3 Evaluation of catalytic epoxidation performance of various catalysts

[0081]

[0082] As can be seen from the results of the above examples and comparative examples, compared with unmodified Ti-TUD-1(S), the one-step fluorine-modified F-Ti-TUD-1(S) and the F-Ti-TUD-1(0.05-S) prepared by the present invention showed improved conversion of cyclohexyl hydroperoxide and selectivity for propylene oxide when used in the epoxidation reaction of cyclohexyl hydroperoxide; while the F-Ti-TUD-1(m) prepared by first fluorine modification and then base modification showed significantly reduced conversion of cyclohexyl hydroperoxide and selectivity for propylene oxide when used in the epoxidation reaction of cyclohexyl hydroperoxide and propylene. From the overall results, the catalyst of the present invention achieved the best results.

[0083] In addition, when the same catalyst is applied to propylene-isopropylbenzene hydroperoxide and propylene-cyclohexyl hydroperoxide systems, there is no significant difference in the oxygen source conversion rate, but there is a significant difference in the selectivity of epoxide products. This is related to the volatility of active oxygen in the oxygen source. The active oxygen in isopropylbenzene hydroperoxide is more likely to epoxidize with olefins to form epoxides.

[0084] The above analysis shows that when the catalyst prepared by the present invention is used in the epoxidation system of propylene and cyclohexyl hydroperoxide, the cyclohexyl hydroperoxide conversion rate and propylene oxide selectivity are further improved, and the overall selectivity of alcohols and ketones is also high. Therefore, the catalyst has a wide range of application value in industrial applications and has good application prospects.

Claims

1. A method for preparing a modified titanium silicon catalyst, characterized in that: It consists of the following steps in order: (1) The in situ synthesized Ti-TUD-1 mesoporous material, the alkaline compound and water are uniformly mixed to obtain a mixed solution A; (2) aging, washing, and drying the mixed solution A obtained in step (1) to obtain powder a; (3) uniformly mixing the powder a obtained in step (2), the fluorine-containing compound, and the solvent to obtain a mixed solution B; (4) aging, washing, drying, and calcining the mixed solution B obtained in step (3) to obtain powder b; (5) subjecting the powder b obtained in step (4) to silanization treatment to obtain a modified titanium silicon catalyst; In step (1), the alkaline compound is one or more of sodium hydroxide, sodium carbonate, ammonia water, diethanolamine, triethanolamine, tetraethylammonium hydroxide, tetramethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide, and the amount ratio of Ti-TUD-1, alkaline compound and H2O is 100 g: (0.01~2) g: (5~200) g; In step (2), the aging temperature is 20-65°C, and the time is 12-72 hours; the drying temperature is 65-150°C, and the time is 5-48 hours; The fluorine-containing compound is one or more of sodium fluoride, hexafluorotitanic acid, ammonium fluoride, and ammonium fluorosilicate, and the solvent is one or more of nitric acid, methanol, water, and cyclohexane; In step (4), the aging temperature is 20~65°C, and the time is 12~72h; the drying temperature is 65~150°C, and the time is 5~48h; and the roasting temperature is 400~800°C, and the time is 2~18h.

2. The method for preparing the modified titanium silicon catalyst according to claim 1, wherein The mass ratio of Ti-TUD-1, methanol, and ammonium fluoride is 1:(10~120):(0.05~20).

3. Use of the modified titanium silicon catalyst obtained by the preparation method of the modified titanium silicon catalyst according to claim 1 or 2 in the epoxidation reaction of olefins with alkyl hydroperoxide in the presence of a solvent.

4. The use according to claim 3, characterized in that The alkyl hydroperoxide is cumene hydroperoxide, cyclohexyl hydroperoxide, tert-butyl hydroperoxide or ethylbenzene hydroperoxide; the solvent is cumene, cyclohexane, tert-butyl alcohol or ethylbenzene; the olefin is C3~C 10 of chain or cyclic alkenes.

5. The use according to claim 3, characterized in that The reaction temperature is 70~180°C, the time is 0.5~5h, the reaction pressure is 0.1~4MPa, the mass fraction of the catalyst in the reaction liquid is 0.5%~6%, the mass fraction of the alkyl hydroperoxide in the solvent is 5%~40%, and the molar ratio of olefin to alkyl hydroperoxide is (0.5~30):1.

Images