A method for catalytic epoxidation of olefins by in-situ synthesis of hydrogen peroxide from hydrogen and oxygen

Abstract

A green synthesis technology for the in-situ synthesis of hydrogen peroxide catalyzing the epoxidation of macromolecular olefins via hydrogen and oxygen is disclosed. This technology involves synthesizing a bimetallic-supported titanium-silicon molecular sieve catalyst with specific large pore sizes and rich in defective titanium sites (Ti-OH). The bimetallic sites are targeted to the vicinity of these defective titanium sites, allowing hydrogen peroxide synthesized on the metal surface via catalytic hydrogen and oxygen transfer directly to these titanium sites on the titanium-silicon molecular sieve surface. This enables in-situ epoxidation of macromolecular olefins using hydrogen peroxide. This technology improves upon the safety issues of liquid-phase hydrogen peroxide storage and transportation in traditional macromolecular olefin epoxidation processes, enabling the direct epoxidation of macromolecular olefins using hydrogen and oxygen.

Description

Technical Field

[0001] This application relates to a method for the epoxidation of macromolecular olefins, specifically, to a catalyst synthesis method for the epoxidation of macromolecular olefins catalyzed by in-situ synthesis of hydrogen peroxide from hydrogen and oxygen. Background Technology

[0002] The petrochemical and chemical product markets continue to show a trend towards high-end and specialized demand, creating an urgent need to develop differentiated, high-value products. As a comonomer for producing high-value-added polyethylene, 1-hexene has wide applications in polymer materials, fine chemicals, and pharmaceuticals, and is an important organic synthesis intermediate, primarily used as a comonomer for producing high-value-added polyethylene. Ample raw material sources have laid the foundation for extending the downstream industrial chain of 1-hexene; the resulting challenge is the urgent need to develop high-value-added downstream products of 1-hexene.

[0003] Epoxides are the third largest class of olefin derivatives and an important chemical intermediate, widely used in the production of diols, polyethers, polyurethanes, surfactants, bactericides, plasticizers, and other chemical products. They are also important pharmaceutical intermediates. 1,2-Epoxyhexane is a high-value-added chemical intermediate that can be used as a medical sterilization material in special applications. Utilizing its active terminal groups, it can also be used to synthesize novel polyurethane elastomers, highly oil-soluble polyether lubricants, cationic lipid polymers (for mRNA self-assembled tumor vaccines), nonionic surfactants, and demulsifiers, among other high-end chemicals. Its hydrolysis product, 1,2-hexanediol, is an important medical intermediate with excellent ozone resistance and antibacterial effects, widely used in high-end cosmetic moisturizers and dispersants for high-grade inks.

[0004] Currently, the TS-1 / H2O2 catalytic system is widely used in the epoxidation reaction of macromolecular liquid phase olefins. However, due to the instability of H2O2 oxidant, acid and halide stabilizers are usually added during storage and transportation. However, these stabilizers reduce catalyst stability, corrode the reactor and reduce reactor life, and increase the cost of improving product purity.

[0005] Therefore, developing a catalyst and process for in-situ efficient generation of H2O2 and direct catalysis of 1-hexene epoxidation would greatly improve traditional liquid-phase H2O2 catalytic systems. Chinese Patent Application Publication No. CN1226241A discloses an epoxidation reaction of olefins with oxygen in the presence of hydrogen and a catalyst, such as the preparation of propylene oxide from propylene. In that application, the TS-1 support, with its interconnected, approximately cylindrical 10-cyclic pores with a diameter of about 0.5 nm, is difficult to effectively oxidize large olefin molecules to alkylene oxides. Based on this, this application is hereby filed. Summary of the Invention

[0006] One objective of this application is to provide a method for the direct preparation of epoxides from macromolecular olefins (e.g., 1-hexene) and oxygen. By preparing a suitable catalyst, macromolecular olefins can be efficiently prepared into epoxides, thereby improving the conversion rate of olefins and the selectivity of epoxides.

[0007] Specifically, a method for preparing epoxides from olefins includes reacting olefins, oxygen, and hydrogen in the presence of a catalyst to generate epoxides, wherein the olefins are olefins with four or more carbon atoms, and the catalyst includes a metal and a titanium-silicon molecular sieve, wherein the metal includes one or a mixture of any two or more metals such as Au, Pd, Ir, Sn, Ni, and Zn.

[0008] This synthesis technique utilizes hydrogen and oxygen catalytic epoxidation of macromolecular olefins. Without introducing liquid hydrogen peroxide, hydrogen peroxide is synthesized in situ via the in-situ catalysis of hydrogen and oxygen by a metal active component on the catalyst surface. Because the metal active component is located near titanium sites, the hydrogen peroxide further migrates to these active titanium sites on the support surface. Furthermore, the presence of specific mesopores (approximately 2 nm) in TS-1 or TS-2 allows macromolecular olefins to diffuse to the titanium active sites and react with the surface hydrogen peroxide, thereby catalyzing the in-situ formation of the corresponding epoxide compounds from the macromolecular olefins. Attached Figure Description

[0009] Figure 1 UV-Vis image of titanium-silicon molecular sieve in Example 1

[0010] Figure 2 XRD pattern of titanium-silicon molecular sieve in Example 1

[0011] Figure 3 TEM image of titanium-silicon molecular sieve in Example 1

[0012] Figure 4 Nitrogen adsorption-desorption curves and pore size distribution of titanium-silicon molecular sieves in Example 1

[0013] Figure 5 XRD pattern of titanium-silicon molecular sieve in Example 2

[0014] Figure 6 SEM image of titanium-silicon molecular sieve in Example 2 Detailed Implementation

[0015] The method for preparing epoxides according to this application is described in further detail below. This does not limit the scope of protection of this application, which is defined by the claims. Certain specific details disclosed provide a comprehensive understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments can be implemented using other materials, etc., without employing one or more of these specific details.

[0016] Unless the context requires otherwise, the terms "comprising" and "including" in the specification and claims shall be understood as open-ended and inclusive, meaning "including, but not limited to".

[0017] The terms "implementation," "an implementation," "another implementation," or "certain implementations" used in this specification refer to specific features, structures, or characteristics described in relation to the implementation, which are included in at least one implementation. Therefore, "implementation," "an implementation," "another implementation," or "certain implementations" do not necessarily all refer to the same implementation. Furthermore, specific features, structures, or characteristics can be combined in any way within one or more implementations. Each feature disclosed in this specification can be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the disclosed features are merely general examples of equivalent or similar features.

[0018] Definition of ultraviolet light: Ultraviolet light is the general term for radiation with wavelengths of 10-400 nm in the electromagnetic spectrum.

[0019] Definition of macromolecular olefins: Macromolecular olefins in this application include olefins with four or more carbon atoms. For example: 1-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 3-hexene, octene, etc.

[0020] In existing propylene gas-phase epoxidation processes, the internal active sites of the titanium silicate molecular sieve catalyst (TS-1 or TS-2, e.g., TS-1: 0.55 nm) can be fully utilized due to the smaller molecular dynamic diameter (0.3 nm) of propylene compared to the pore size of the TS-1 or TS-2 titanium silicate molecular sieve catalyst (e.g., TS-1: 0.55 nm), and the ability to diffuse product molecules out of the pores. However, for large olefins, such as 1-hexene, the molecular dynamic diameter is 0.6 nm, which is larger than the 0.55 nm pore size of conventional titanium silicate molecular sieves, making it difficult to access and utilize the internal active sites. Therefore, achieving catalysts and processes that can couple molecular sieve pore design with in-situ efficient catalytic hydrogen-oxygen to H2O2 generation and direct catalytic epoxidation of large olefins presents a significant challenge.

[0021] This application discloses a method for preparing epoxides from olefins, comprising reacting olefins, oxygen, and hydrogen in the presence of a catalyst to generate epoxides, wherein the olefins are olefins with four or more carbon atoms, and the catalyst comprises a metal and a titanium-silicon molecular sieve, wherein the metal comprises one or a mixture of any two or more of the following metals: Au, Pd, Ir, Sn, Ni, and Zn.

[0022] The method for preparing the catalyst includes:

[0023] (1) Water, organic template agent, silicon source, titanium source and mesoporous regulator are directly mixed to obtain mixed solution I.

[0024] (2) Mixed solution I was reacted under ultraviolet light for a period of time to obtain mixed solution II;

[0025] (3) Crystallize the mixed solution II, cool, centrifuge, dry, and calcine the crystallized solution to obtain a titanium silicon molecular sieve without non-framework titanium.

[0026] (4) A solution containing the active metal component is impregnated onto a titanium-silicon molecular sieve, and after drying and reduction, a catalyst is obtained.

[0027] In some embodiments, the mesoporous agent includes n-octyltrimethylammonium bromide (C8), decaalkyltrimethylammonium bromide (C10), dodecyltrimethylammonium bromide (C12), and hexadecyltrimethylammonium bromide (C16).

[0028] The molar ratio of silicon source, organic template agent, titanium source, and mesoporous agent is 1:(0.1-0.8):(0.01-0.3):(0.01-0.2).

[0029] In some embodiments, the molar ratio of silicon source, organic template agent, titanium source, and mesoporous agent is 1:0.5:0.06:0.15.

[0030] Definition of silicon source: The silicon source in this application is selected from water-soluble or water-soluble silicon-containing compounds, usually referring to tetraethyl orthosilicate and silica sol.

[0031] Titanium source definition: The titanium source in this application is selected from water-soluble or water-soluble titanium-containing compounds. These include tetrabutyl titanate, tetraethyl titanate, tetraisopropyl titanate, titanium trichloride, and titanium tetrachloride.

[0032] Organic template agents include, for example, ethylenediamine, tetraethylammonium hydroxide, n-butylamine, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapropylammonium bromide, or tetrabutylammonium bromide.

[0033] In titanium-silicon molecular sieve crystals, excessively large pore sizes reduce the contact opportunities between olefin molecules and active titanium sites within the pores, while excessively small pore sizes prevent olefin molecules from entering and exiting the molecular sieve pores for reaction. Therefore, preferably, the mesoporous agent includes n-octyltrimethylammonium bromide (C8), decaalkyltrimethylammonium bromide (C10), dodecyltrimethylammonium bromide (C12), and hexadecyltrimethylammonium bromide (C16). By using the above-mentioned different mesoporous agents, the length of the carbon chain of the mesoporous agent can be continuously controlled according to the kinetic diameter of the macromolecular olefin. While adjusting the pore size, the above-mentioned mesoporous agents promote the effective formation of surface defect titanium sites (Ti-OH, such as tetracoordinated titanium Ti(OSi)3OH and hexacoordinated titanium Ti(OSi)2(H2O)2(OH)2) during crystallization. These titanium sites interact with the metal precursor through surface hydroxyl groups, thereby effectively improving the spatial placement of the metal precursor.

[0034] In step (4), the pH of the solution containing the active metal component is adjusted to be lower than the value at which the corresponding metal precipitates and higher than the value at which the corresponding noble metal ligand is gradually replaced, so as to ensure that there is a strong charge interaction between the metal charge and the titanium site of the support, thereby ensuring that the metal particles can be uniformly dispersed on the surface of the mesoporous titanium silicate molecular sieve.

[0035] In some embodiments, in step (4), the solution containing the active metal component impregnated onto the titanium-silicon molecular sieve has a pH of 5.0-8.0. More preferably, the pH is 7.0-7.6.

[0036] In some embodiments, in step (4), the pH of the solution containing the active metal component impregnated onto the titanium-silicon molecular sieve is approximately 7.3.

[0037] The titanium-silicon molecular sieve prepared in this application is produced by mixing the above-mentioned raw materials in a specific ratio and then undergoing subsequent processes such as ultraviolet light, crystallization, and calcination. This process effectively generates surface defect titanium sites (Ti-OH, such as tetracoordinated titanium Ti(OSi)3OH and hexacoordinated titanium Ti(OSi)2(H2O)2(OH)2) on the structure of the titanium-silicon molecular sieve. Then, in a solution containing active metal with a pH value of 5.0-8.0, especially in the range of 7.0-7.6, during the loading process, metal elements are more likely to settle near the titanium sites, but the surface titanium species are not covered.

[0038] In some embodiments, the active component loaded on the titanium silicon molecule is any two metal elements selected from Au, Pd, Ir, Sn, Ni, and Zn.

[0039] By adjusting the pH of a solution containing an active metal component, the hydrolysis kinetics of different metal precursors can be modulated, achieving co-regulation of the size and charge of two different metal precursors. Excessive hydrolysis leads to increased metal-hydroxyl coordination, resulting in precipitation, while insufficient hydrolysis reduces metal-hydroxyl coordination, thus inhibiting the charge interaction between surface titanium sites and metal hydroxyl compounds. Utilizing the charge interaction between specific precursors and support titanium sites, targeted placement of metal sites on titanium sites is achieved. After drying and reduction, a bimetallic targeted supported titanium-silicon molecular sieve catalyst material is obtained. In particular, for dual active components Au and Pd, or Au and Zn, or Pd and Zn, targeted placement near the framework titanium sites is more advantageous.

[0040] In some embodiments, the active components supported on the titanium silicon molecules are two metal elements, Au and Pd. Preferably, the molar ratio of Au to Pd is 1:(0.5-2.0). More preferably, the molar ratio of Au to Pd is approximately 1:1.

[0041] In some embodiments, the active components supported on the titanium silicon molecules are two metal elements, Au and Zn. Preferably, the molar ratio of Au to Zn is 1:(0.5-2.5). More preferably, the molar ratio of Au to Zn is about 1:2.

[0042] In some embodiments, the active components supported on the titanium silicon molecules are two metal elements, Pd and Zn. Preferably, the molar ratio of Pd to Zn is 1:(0.5-2.5). More preferably, the molar ratio of Pd to Zn is about 1:1.5.

[0043] In some embodiments, the content of the active component metal element supported on the titanium-silicon molecules is 0.1-2 wt%. The loading amount refers to the percentage of the mass of the metal element relative to the mass of the catalyst.

[0044] Solutions containing Au, Pd, Ir, Sn, Ni, and Zn metals include: metal chlorides, acetylacetonates, acetate compounds, or nitrate compounds. Examples include: chloroauric acid, gold acetate, chloropalladium acid, palladium acetate, zinc nitrate, and zinc sulfate.

[0045] As in step (1), after the five solutions are directly mixed, the rapid hydrolysis rate of titanium means that a short stirring time is not conducive to thorough mixing of the solutions, while a long stirring time will generate a large amount of non-framework titanium. Therefore, the stirring time should be shorter than the time required for the generation of a large amount of non-framework titanium, while ensuring thorough mixing of the solutions.

[0046] In some embodiments, the reaction stirring time in step (1) is 0.01-0.5 h; more preferably, the reaction stirring time is 0.1-0.2 h.

[0047] As in step (1), the reaction stirring temperature after mixing the five solutions should be higher than the freezing point of the mixture and lower than the decomposition temperature of the organic template agent.

[0048] In some embodiments, the mixing temperature is above 0°C and below 100°C; more preferably, the mixing temperature is above 10°C and below 35°C.

[0049] As in step (2), the reaction stirring time should be higher than the minimum time required for the hydroxyl radicals generated by ultraviolet radiation to decompose the titanium and silicon sources, and lower than the time required for the titanium and silicon monomers to undergo self-polymerization.

[0050] In some embodiments, the stirring time is 0.01-24 h. More preferably, the stirring time is 0.03-0.2 h.

[0051] In some implementations, such as in step (2), the ultraviolet radiation used to generate hydroxyl radicals should have an intensity greater than 10W.

[0052] In some implementations, such as step (2), the ultraviolet radiation power is 100-1000W.

[0053] In some implementations, such as step (2), the ultraviolet radiation power is 500-1000W.

[0054] In some embodiments, such as in step (3), the crystallization temperature should be higher than the molecular sieve growth temperature and lower than the tolerance temperature of the molecular sieve skeleton; preferably, the crystallization temperature should be higher than 100°C and lower than 200°C; more preferably, the crystallization temperature should be higher than 140°C and lower than 180°C.

[0055] In some implementations, such as in step (3), preferably, the crystallization method is rotational crystallization.

[0056] In step (3), the calcination method should be performed at a temperature higher than the decomposition temperature of the template agent and lower than the tolerance temperature of the molecular sieve skeleton, and the heating rate should also be lower than the tolerance heating rate of the molecular sieve skeleton. The calcination time should also be lower than the tolerance calcination time of the molecular sieve skeleton.

[0057] In some embodiments, in step (3), the heating rate during calcination is 1-10℃ / min, the calcination temperature is 500-700℃, and the calcination time is 4-8h.

[0058] Preferably, in step (3), the heating rate during calcination is 4-6℃ / min, the calcination temperature is 550-600℃, and the calcination time is 5-7h.

[0059] The reduction process in step (4) includes calcining the dried solid material in a reducing agent atmosphere. The reducing agent may include, for example, a hydrogen gas mixture with a hydrogen volume content of approximately 1%.

[0060] The roasting temperature is controlled at 300-400℃. Preferably, roasting is carried out at 300-400℃ for 3.5-5 hours.

[0061] In the method for preparing epoxides in this application, for macromolecular olefins, such as 1-hexene, it is also possible to couple molecular sieve channel design and in-situ efficient catalytic generation of H2O2 from hydrogen and oxygen, and directly catalyze the epoxidation of macromolecular olefins. Correspondingly, the conversion rate of olefins and the selectivity of epoxides are both increased.

[0062] The macromolecular olefin is preferably a mono-olefin or diene with 6 or more carbon atoms, such as 1-hexene, 2-hexene, 3-hexene, octene, etc. More preferably, it is C6-C. 10 olefins.

[0063] In some embodiments, the reaction temperature is 50-100°C. Preferably, the reaction temperature is about 80°C.

[0064] In the reaction system, oxygen can be replaced by other oxygen-containing molecules, such as air.

[0065] In some embodiments, the volume ratio of hydrogen to oxygen is 1:6 to 1:1, and preferably, the volume ratio of hydrogen to oxygen is 1:1.

[0066] At normal temperature and pressure, the flow rate ratio (mL / min) of oxygen (gaseous) to olefins (liquid) is (1000-4000):1.

[0067] Preferably, the oxygen to olefin flow rate ratio (mL / min) is 3500:1.

[0068] The ambient temperature is approximately 25°C, and the ambient pressure is 101 kPa.

[0069] In the reaction system, nitrogen and other gases need to be added to dilute the hydrogen content. Preferably, the nitrogen content is greater than or equal to 50%.

[0070] The selectivity for the oxidation of macromolecular olefins to prepare epoxides in this application is over 90%, and the conversion rate is over 20%.

[0071] In addition, the hydrogen utilization rate is high in the macromolecular olefin oxidation to epoxide alkane system of this application.

[0072] The method for preparing epoxides from macromolecular olefins of this application is further illustrated below with reference to specific embodiments.

[0073] Example 1

[0074] Synthesis of metal-supported titanium-silicon molecular sieves

[0075] Take 15g of tetrapropylammonium hydroxide (25wt%), add 5g of water, 0.8052g of tetrabutyl titanate, 10g of tetraethyl orthosilicate, and 2g of hexadecyltrimethylammonium bromide. Stir at 30℃ for half an hour, then under 1000W ultraviolet light for approximately 4 hours. Then, place the solution in a crystallization vessel and crystallize at 170℃ for 50 hours. After removal, cool, centrifuge, dry at 80℃, and calcine at 550℃ for 8 hours. Dissolve 0.009g of chloroauric acid and 0.011g of potassium chloropalladate in 4.5mL of water. Adjust the pH of the mixed solution to 7.3 using sodium carbonate, then add deionized water to bring the volume to 5mL. Impregnate 0.4mL of the above metal solution onto 0.5g of titanium-silicon molecular sieve, vacuum dry at room temperature, and then reduce at 400℃ for 4 hours in an H2 / Ar (1% hydrogen by volume) atmosphere to obtain a bimetallic supported titanium-silicon molecular sieve catalyst.

[0076] Ultraviolet (UV) analysis was performed on the metal-free titanium-silicon molecular sieve prepared in this embodiment (see attached figure). Figure 1 X-ray powder diffraction analysis (see attached) Figure 2 ) and transmission electron microscopy analysis (see attached) Figure 3 ).exist Figure 1 The peak at 260 nm represents the abundance of defective titanium sites (Ti-OH) in the titanium-silicon molecular sieve. Figure 2 XRD and attachment Figure 3 TEM images show that the titanium silicate molecular sieve exhibits a typical MFI crystal structure. Furthermore, nitrogen physical adsorption-desorption curves and pore size distribution indicate (attached) Figure 4 As shown, this titanium-silicon molecular sieve has a specific mesoporous pore size (~2 nm). This specific defective titanium site facilitates the directional placement of metals, and the pore size of 2 nm also facilitates the diffusion, desorption, and reaction of reactant and product molecules within the pores.

[0077] Example 2

[0078] Synthesis of metal-supported titanium-silicon molecular sieves

[0079] Take 15g of tetrapropylammonium hydroxide (25wt%), add 5g of water, 0.8052g of tetrabutyl titanate, 7.5g of silica sol (25wt%), and 2g of dodecyltrimethylammonium bromide. Stir at 30℃ for half an hour, then under 1000W ultraviolet light for approximately 4 hours. Then, place the solution in a crystallization vessel and crystallize at 170℃ for 50 hours. After removal, cool, centrifuge, dry at 80℃, and calcine at 550℃ for 8 hours. This yields a molecular sieve free of non-framework titanium. Dissolve 0.009g of chloroauric acid and 0.011g of potassium chloropalladate in 4.5mL of water. Adjust the pH of the mixed solution to 7.3 using sodium carbonate, then add deionized water to bring the volume to 5mL. Take 0.4 mL of the above metal solution and immerse it on 0.5 g of titanium-silicon molecular sieve. Dry it under vacuum at room temperature, and then reduce it at 400 °C for 4 h in an H2 / Ar (hydrogen volume content 1%) atmosphere to obtain a bimetallic supported titanium-silicon molecular sieve catalyst.

[0080] The unloaded metal titanium-silicon molecular sieve prepared in this embodiment was analyzed by XRD and SEM, as follows: Figure 5 and 6 This indicates that titanium silicate molecular sieves have a typical MFI crystal structure.

[0081] Example 3

[0082] Synthesis of metal-supported titanium-silicon molecular sieves

[0083] Take 15g of tetrapropylammonium hydroxide (25wt%), add 5g of water, 0.5398g of tetraethyl titanate, 7.5g of silica sol (25wt%), and 2g of cetyltrimethylammonium bromide. Stir at 30℃ for half an hour, then under 1000W ultraviolet light for approximately 4 hours. Then, place the solution in a crystallization vessel and crystallize at 170℃ for 50 hours. After removal, cool, centrifuge, dry at 80℃, and calcine at 550℃ for 8 hours. This yields a molecular sieve free of non-framework titanium. Dissolve 0.009g of chloroauric acid and 0.011g of potassium chloropalladate in 4.5mL of water. Adjust the pH of the mixed solution to 7.3 using sodium carbonate, then add deionized water to bring the volume to 5mL. Take 0.4 mL of the above metal solution and immerse it on 0.5 g of titanium-silicon molecular sieve. Dry it under vacuum at room temperature, and then reduce it at 400 °C for 4 h in an H2 / Ar (hydrogen volume content 1%) atmosphere to obtain a bimetallic supported titanium-silicon molecular sieve catalyst.

[0084] Example 4

[0085] Synthesis of metal-supported titanium-silicon molecular sieves

[0086] Take 17g of tetrabutylammonium hydroxide (25wt%), add 5g of water, 0.8052g of tetrabutyl titanate, 10g of tetraethyl orthosilicate, and 2g of dodecyltrimethylammonium bromide. Stir at 30℃ for half an hour, then under 1000W ultraviolet radiation for approximately 4 hours. Then, place the solution in a crystallization vessel and crystallize at 170℃ for 50 hours. After removal, cool, centrifuge, dry at 80℃, and calcine at 550℃ for 8 hours. Dissolve 0.009g of chloroauric acid and 0.011g of potassium chloropalladate in 4.5mL of water. Adjust the pH of the mixed solution to 7.3 using sodium carbonate, then add deionized water to bring the volume to 5mL. Impregnate 0.4mL of the above metal solution onto 0.5g of titanium-silicon molecular sieve, vacuum dry at room temperature, and reduce at 400℃ for 4 hours in an H2 / Ar (1% hydrogen by volume) atmosphere to obtain a bimetallic supported titanium-silicon molecular sieve catalyst.

[0087] Example 5

[0088] Synthesis of metal-supported titanium-silicon molecular sieves

[0089] Take 15g of tetrapropylammonium hydroxide (25wt%), add 5g of water, 0.8052g of tetrabutyl titanate, 10g of tetraethyl orthosilicate, and 2g of hexadecyltrimethylammonium bromide. Stir at 30℃ for half an hour, then under 1000W ultraviolet radiation for approximately 4 hours. Then, place the solution in a crystallization vessel and crystallize at 170℃ for 50 hours. After removal, cool, centrifuge, dry at 80℃, and calcine at 550℃ for 8 hours. Dissolve 0.011g of potassium chloropalladate and 0.014g of chloroplatinic acid in 4.5mL of water. Adjust the pH of the mixed solution to 7.3 using sodium carbonate, then add deionized water to bring the volume to 5mL. Impregnate 0.4mL of the above metal solution onto 0.5g of titanium-silicon molecular sieve, vacuum dry at room temperature, and reduce at 400℃ for 4 hours in an H2 / Ar (1% hydrogen by volume) atmosphere to obtain a bimetallic supported titanium-silicon molecular sieve catalyst.

[0090] Example 6

[0091] Synthesis of metal-supported titanium-silicon molecular sieves

[0092] Take 15g of tetrapropylammonium hydroxide (25wt%), add 5g of water, 0.8052g of tetrabutyl titanate, 10g of tetraethyl orthosilicate, and 2g of dodecyltrimethylammonium bromide. Stir at 30℃ for half an hour, then under 1000W ultraviolet light for approximately 4 hours. Then, place the solution in a crystallization vessel and crystallize at 170℃ for 50 hours. After removal, cool, centrifuge, dry at 80℃, and calcine at 550℃ for 8 hours. Dissolve 0.011g of potassium chloropalladate and 0.008g of zinc nitrate in 4.5mL of water. Adjust the pH of the mixed solution to 7.3 using sodium carbonate, then add deionized water to bring the volume to 5mL. Impregnate 0.4mL of the above metal solution onto 0.5g of titanium-silicon molecular sieve, vacuum dry at room temperature, and reduce at 400℃ for 4 hours in an H2 / Ar (1% hydrogen by volume) atmosphere to obtain a bimetallic supported titanium-silicon molecular sieve catalyst.

[0093] Example 7

[0094] Synthesis of metal-supported titanium-silicon molecular sieves

[0095] Take 15g of tetrapropylammonium hydroxide (25wt%), add 5g of water, 0.8052g of tetrabutyl titanate, 10g of tetraethyl orthosilicate, and 2g of hexadecyltrimethylammonium bromide. Stir at 30℃ for half an hour, then under 1000W ultraviolet light for approximately 4 hours. Then, place the solution in a crystallization vessel and crystallize at 170℃ for 50 hours. After removal, cool, centrifuge, dry at 80℃, and calcine at 550℃ for 8 hours. Dissolve 0.009g of chloroauric acid and 0.011g of potassium chloropalladate in 4.5mL of water respectively. Adjust the pH of the mixed solutions to 7.3 using sodium carbonate, then add deionized water to bring the volume to 5mL. Impregnate 0.4mL of the above chloroauric acid metal solution onto 0.5g of titanium-silicon molecular sieve and vacuum dry at room temperature. Subsequently, 0.4 mL of the potassium chloropalladium metal solution was impregnated onto 0.5 g of titanium-silicon molecular sieve, dried under vacuum at room temperature, and reduced at 400 °C for 4 h in an H2 / Ar (hydrogen volume content 1%) atmosphere to obtain the bimetallic supported titanium-silicon molecular sieve catalyst.

[0096] Example 8

[0097] Synthesis of metal-supported titanium-silicon molecular sieves

[0098] Take 15g of tetrapropylammonium hydroxide (25wt%), add 5g of water, 0.8052g of tetrabutyl titanate, 10g of tetraethyl orthosilicate, and 2g of dodecyltrimethylammonium bromide. Stir at 30℃ for half an hour, then under 1000W ultraviolet light for approximately 4 hours. Then, place the solution in a crystallization vessel and crystallize at 170℃ for 50 hours. After removal, cool, centrifuge, dry at 80℃, and calcine at 550℃ for 8 hours. Dissolve 0.009g of chloroauric acid and 0.008g of zinc nitrate separately in 4.5mL of water. Adjust the pH of the mixed solutions to 7.3 using sodium carbonate, then add deionized water to bring the volume to 5mL. Impregnate 0.4mL of the above chloroauric acid metal solution onto 0.5g of titanium-silicon molecular sieve and vacuum dry at room temperature. Subsequently, 0.4 mL of the zinc nitrate metal solution was impregnated onto 0.5 g of titanium-silicon molecular sieve, dried under vacuum at room temperature, and reduced at 400 °C for 4 h in an H2 / Ar (hydrogen volume content 1%) atmosphere to obtain the bimetallic supported titanium-silicon molecular sieve catalyst.

[0099] Comparative Example 1

[0100] Synthesis of metal-supported titanium-silicon molecular sieves (Au-Pd metal placement without targeted regulation)

[0101] Take 15g of tetrapropylammonium hydroxide (25wt%), add 5g of water, 0.8052g of tetrabutyl titanate, 10g of tetraethyl orthosilicate, and 2g of hexadecyltrimethylammonium bromide. Stir at 30℃ for half an hour, then under 1000W ultraviolet light for approximately 4 hours. Then, place the solution in a crystallization vessel and crystallize at 170℃ for 50 hours. After removal, cool, centrifuge, dry at 80℃, and calcine at 550℃ for 8 hours. Dissolve 0.009g of chloroauric acid and 0.011g of potassium chloropalladate in 4.5mL of water, then add deionized water to bring the volume to 5mL. Impregnate 0.4mL of the above metal solution onto 0.5g of titanium-silicon molecular sieve, vacuum dry at room temperature, and reduce at 400℃ for 4 hours in an H2 / Ar (1% hydrogen by volume) atmosphere to obtain a bimetallic supported titanium-silicon molecular sieve catalyst.

[0102] Comparative Example 2

[0103] Synthesis of metal-supported titanium-silicon molecular sieves (Au-Zn metal placement without targeted regulation)

[0104] Take 15g of tetrapropylammonium hydroxide (25wt%), add 5g of water, 0.8052g of tetrabutyl titanate, and 10g of tetraethyl orthosilicate. Stir at 30℃ for half an hour, then add 2g of hexadecyltrimethylammonium bromide. Then, under 1000W ultraviolet light irradiation, crystallize for approximately 4 hours. Next, place the solution in a crystallization vessel and crystallize at 170℃ for 50 hours. After removal, cool, centrifuge, dry at 80℃, and calcine at 550℃ for 8 hours. Dissolve 0.009g of chloroauric acid and 0.008g of zinc nitrate separately in 4.5mL of water, then add deionized water to bring the volume to 5mL. Impregnate 0.4mL of the above chloroauric acid metal solution onto 0.5g of titanium-silicon molecular sieve and vacuum dry at room temperature. Subsequently, 0.4 mL of the zinc nitrate metal solution was impregnated onto 0.5 g of titanium-silicon molecular sieve, dried under vacuum at room temperature, and reduced at 400 °C for 4 h in an H2 / Ar (hydrogen volume content 1%) atmosphere to obtain the bimetallic supported titanium-silicon molecular sieve catalyst.

[0105] Comparative Example 3

[0106] Synthesis of metal-supported titanium silicate molecular sieves (metal-free species)

[0107] Take 15g of tetrapropylammonium hydroxide (25wt%), add 5g of water, 0.8052g of tetrabutyl titanate, 10g of tetraethyl orthosilicate, and 2g of hexadecyltrimethylammonium bromide. Stir at 30℃ for half an hour, then under 1000W ultraviolet light irradiation for approximately 4 hours. Then, place the solution in a crystallization vessel and crystallize at 170℃ for 50 hours. After removal, cool, centrifuge, dry at 80℃, and calcine at 550℃ for 8 hours to obtain the titanium-silicon molecular sieve catalyst.

[0108] Comparative Example 4

[0109] Synthesis of metal-supported pure silica molecular sieves (titanium-free species)

[0110] Take 15g of tetrapropylammonium hydroxide (25wt%), add 5g of water, 10g of tetraethyl orthosilicate, and 2g of hexadecyltrimethylammonium bromide. Stir at 30℃ for half an hour, then under 1000W ultraviolet light for approximately 4 hours. Then, place the solution in a crystallization vessel and crystallize at 170℃ for 50 hours. After removal, cool, centrifuge, dry at 80℃, and calcine at 550℃ for 8 hours. Dissolve 0.009g of chloroauric acid and 0.011g of potassium chloropalladate in 4.5mL of water. Adjust the pH of the mixed solution to 7.3 using sodium carbonate, then add deionized water to bring the volume to 5mL. Impregnate 0.4mL of the above metal solution onto 0.5g of pure silicon molecular sieve, vacuum dry at room temperature, and reduce at 400℃ for 4 hours in an H2 / Ar (1% hydrogen by volume) atmosphere to obtain a bimetallic supported pure silicon molecular sieve catalyst.

[0111] Comparative Example 5

[0112] Synthesis of metal-supported titanium-silicon molecular sieves (without directed regulation of titanium species)

[0113] Take 15g of tetrapropylammonium hydroxide (25wt%), add 5g of water, 0.8052g of tetrabutyl titanate, 10g of tetraethyl orthosilicate, and 2g of hexadecyltrimethylammonium bromide. Stir at 30℃ for half an hour, then under visible light for approximately 4 hours. Place the solution in a crystallization vessel and crystallize at 170℃ for 50 hours. After removal, cool, centrifuge, dry at 80℃, and calcine at 550℃ for 8 hours. Dissolve 0.009g of chloroauric acid and 0.011g of potassium chloropalladate in 4.5mL of water. Adjust the pH of the mixed solution to 7.3 using sodium carbonate, then add deionized water to bring the volume to 5mL. Impregnate 0.4mL of the above metal solution onto 0.5g of titanium-silicon molecular sieve, vacuum dry at room temperature, and reduce at 400℃ for 4 hours in an H2 / Ar (1% hydrogen by volume) atmosphere to obtain a bimetallic supported titanium-silicon molecular sieve catalyst.

[0114] Comparative Example 6

[0115] Synthesis of metal-supported titanium-silicon molecular sieves (without directional control of pore size)

[0116] Take 15g of tetrapropylammonium hydroxide (25wt%), add 5g of water, 0.8052g of tetrabutyl titanate, and 10g of tetraethyl orthosilicate. Stir at 30℃ for half an hour, then under 1000W ultraviolet radiation for approximately 4 hours. Then, place the solution in a crystallization vessel and crystallize at 170℃ for 50 hours. After removal, cool, centrifuge, dry at 80℃, and calcine at 550℃ for 8 hours. Dissolve 0.009g of chloroauric acid and 0.011g of potassium chloropalladate in 4.5mL of water. Adjust the pH of the mixed solution to 7.3 using sodium carbonate, then add deionized water to bring the volume to 5mL. Impregnate 0.4mL of the above metal solution onto 0.5g of titanium-silicon molecular sieve, vacuum dry at room temperature, and reduce at 400℃ for 4 hours in an H2 / Ar (1% hydrogen by volume) atmosphere to obtain the bimetallic supported titanium-silicon molecular sieve catalyst.

[0117] Experimental Example 1

[0118] This experimental example presents the reaction results of the titanium-containing molecular sieves synthesized in Examples 1-8 after metal loading in the hydrogen-oxygen catalytic epoxidation of 1-butene, 1-hexene, cyclohexene, and 1-octene, as well as the reaction results of the catalysts prepared in Comparative Examples 1-6 in the epoxidation of 1-butene, 1-hexene, cyclohexene, and 1-octene, as shown in Tables 1-4. The reaction conditions included: the epoxidation reaction of macromolecular olefins (1-butene, 1-hexene, cyclohexene, and 1-octene) was carried out in a fixed bed at atmospheric pressure. The catalysts provided above in this invention were used for the reaction, and the reaction gas composition was: hydrogen / oxygen / nitrogen = 1.5 / 1.5 / 7 (volume ratio), with a space velocity of 14000 ml / h. -1g Cat The reaction temperature was 80℃, the olefin flow rate was 0.01mL / min, the catalyst size was 40-100 mesh, and the gas produced in the reaction was analyzed by gas chromatography.

[0119] In Table 1-4, the hydrogen utilization rate refers to the efficiency of converting hydrogen into hydrogen peroxide and using the hydrogen peroxide to oxidize olefins. The feedstock conversion rate refers to the percentage of feedstock that undergoes the reaction relative to the total amount of feedstock. The selectivity of the target product is the percentage of the target product among all products.

[0120] Table 1 Results of 1-Butene Epoxidation

[0121] Example 1 31.2 95.4 45.7 Example 2 35.7 95.7 43.2 Example 3 35.8 91.5 46.9 Example 4 34.2 92.5 50.4 Example 5 38.5 95.3 47.5 Example 6 33.6 94.6 43.6 Example 7 37.3 93.6 44.8 Example 8 38.5 92.7 44.3 Comparative Example 1 12.4 90.2 10.5 Comparative Example 2 13.2 89.5 9.8 Comparative Example 3 0 0 0 Comparative Example 4 0 0 0 Comparative Example 5 5.3 60.3 4.5 Comparative Example 6 6.6 91.2 3.2

[0122] Table 2 Results of 1-Hexene epoxidation reaction

[0123]

[0124]

[0125] Table 3 Results of cyclohexene epoxidation reaction

[0126] Example 1 25.6 93.5 38.5 Example 2 24.5 94.6 39.5 Example 3 26.7 92.5 36.4 Example 4 25.6 91.5 35.7 Example 5 26.4 93.7 33.6 Example 6 27.8 93.6 36.7 Example 7 24.9 91.8 35.8 Example 8 22.6 96.3 32.6 Comparative Example 1 7.8 88.7 6.9 Comparative Example 2 8.4 84.8 7.3 Comparative Example 3 0 0 0 Comparative Example 4 0 0 0 Comparative Example 5 3.7 64.3 2.2 Comparative Example 6 2.5 90.4 1.8

[0127] Table 4 Results of 1-Octenene Epoxidation

[0128]

[0129]

[0130] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the substantive technical content of the present invention. The substantive technical content of the present invention is broadly defined within the scope of the claims. Any technical entity or method implemented by others that is completely identical to or an equivalent modification of the claims is considered to be covered within the scope of the claims.

Claims

1. A method for preparing epoxides from olefins, comprising reacting an olefin, oxygen, and hydrogen in the presence of a catalyst at a temperature of 50-100°C to produce epoxides, wherein the olefin is an olefin with four or more carbon atoms. in, The catalyst comprises an active metal component and a titanium-silicon molecular sieve, wherein the active metal component comprises a mixture of any two of Au, Pd, and Zn. The molar ratio of Au to Pd metal is 1:(0.5-2.0); or the molar ratio of Au to Zn metal is 1:(0.5-2.5); or The molar ratio of Pd to Zn metal is 1: (0.5-2.5). The method for preparing the catalyst includes: (1) Water, organic template agent, silicon source, titanium source and mesoporous regulator are directly mixed to obtain mixed solution I. The molar ratio of silicon source, organic template agent, titanium source, and mesoporous regulator is 1:(0.1-0.8):(0.01-0.3):(0.01-0.2). Organic template agents include ethylenediamine, tetraethylammonium hydroxide, n-butylamine, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapropylammonium bromide, or tetrabutylammonium bromide. The mesoporous regulator includes n-octyltrimethylammonium bromide, decaalkyltrimethylammonium bromide, dodecyltrimethylammonium bromide, or hexadecyltrimethylammonium bromide; (2) Mixed solution I was reacted under ultraviolet light radiation with a radiation power of 500-1000W for a period of time to obtain mixed solution II; (3) Crystallize the mixed solution II, cool, centrifuge, dry, and calcine the crystallized solution to obtain a titanium silicon molecular sieve without non-framework titanium. (4) A solution containing the active metal component with a pH value of 7.0-7.6 is impregnated onto the titanium silicon molecular sieve, and after drying and reduction, a catalyst is obtained.

2. The method according to claim 1, characterized in that, The molar ratio of silicon source, organic template agent, titanium source, and mesoporous regulator is 1:0.5:0.06:0.

15.

3. The method according to claim 1, characterized in that, Silicon sources include tetraethyl orthosilicate and silica sol; Titanium sources include tetrabutyl titanate, tetraethyl titanate, tetraisopropyl titanate, titanium trichloride, and titanium tetrachloride.

4. The method according to claim 1, characterized in that, In step (4), the solution containing Au, Pd, and Zn metals includes: metal chlorides, acetylacetone compounds, acetate compounds, or nitrate compounds.

5. The method according to any one of claims 1-4, characterized in that, The content of active component metal elements loaded on the titanium-silicon molecular sieve is 0.1-2 wt%.

6. The method according to any one of claims 1-4, characterized in that, In step (1), the reaction stirring time is 0.01-0.5 h.

7. The method according to claim 6, characterized in that, The mixing temperature should be above 0℃ and below 100℃.

8. The method according to claim 6, characterized in that, The mixing temperature should be above 10℃ and below 35℃.

9. The method according to any one of claims 1-4, characterized in that, In step (3), the heating rate during roasting is 1-10 ℃ / min, the roasting temperature is 500-700℃, and the roasting time is 4-8h.

10. The method according to any one of claims 1-4, characterized in that, In step (3), the heating rate during roasting is 4-6 ℃ / min, the roasting temperature is 550-600℃, and the roasting time is 5-7h.

11. The method according to any one of claims 1-4, characterized in that, The reaction temperature for the reaction of olefins, oxygen, and hydrogen in the presence of a catalyst is 80°C.

12. The method according to any one of claims 1-4, characterized in that, The volume ratio of hydrogen to oxygen is 1:6 - 1:

1.

13. The method according to any one of claims 1-4, characterized in that, The volume ratio of hydrogen to oxygen is 1:

1.

14. The method according to any one of claims 1-4, characterized in that, At room temperature and pressure, the flow rate ratio of oxygen to liquid olefins is (1000-4000):

1.

15. The method according to any one of claims 1-4, characterized in that, At room temperature and pressure, the flow rate ratio of oxygen to liquid olefins is 3500:

1.

16. The method according to claim 1, characterized in that, The olefins are monoolefins or dienes with 6 or more carbon atoms.

17. The method according to claim 1, characterized in that, The olefin is C6-C. 10 olefins.

18. The method according to claim 1, characterized in that, The olefins are 1-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 3-hexene, or octene.

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