阅读说明：本技术 含钛介孔分子筛催化烯烃环氧化反应的方法 (Method for catalyzing olefin epoxidation reaction by titanium-containing mesoporous molecular sieve ) 是由 夏长久 林民 彭欣欣 朱斌 舒兴田 于 2019-10-29 设计创作，主要内容包括：本发明涉及烯烃环氧化反应领域,公开了一种含钛介孔分子筛催化烯烃环氧化反应的方法,该方法包括：在烯烃环氧化条件下,将烯烃、氧化剂以及任选地溶剂与含钛介孔分子筛接触；其中,所述含钛介孔分子筛包括：介孔分子筛、氟元素和钛元素,钛元素、氟元素和介孔分子筛的摩尔比为1：(0.1-10)：(10-100),其中,介孔分子筛以SiO-2计。由实施例的结果可知,在本发明提供的烯烃环氧化反应中,反应物转化率和目标产物选择性高,其中,环己烯转化率最高为99％,过氧化氢利用率最高为99％,反应产物环氧环己烷和环己二醇选择性总和最高为97％,效果显著。(The invention relates to the field of olefin epoxidation reaction, and discloses a method for catalyzing olefin epoxidation reaction by a titanium-containing mesoporous molecular sieve, which comprises the following steps: contacting an olefin, an oxidant, and optionally a solvent, with a titanium-containing mesoporous molecular sieve under olefin epoxidation conditions; wherein, the titanium-containing mesoporous molecular sieve comprises: the molecular sieve comprises a mesoporous molecular sieve, fluorine and titanium, wherein the molar ratio of the titanium to the fluorine to the mesoporous molecular sieve is 1: (0.1-10): (10-100), wherein the mesoporous molecular sieve is SiO 2 And (6) counting. As can be seen from the results of the examples, in the epoxidation reaction of an olefin provided by the present invention, the reactionThe conversion rate of a reactant and the selectivity of a target product are high, wherein the conversion rate of cyclohexene is 99% at most, the utilization rate of hydrogen peroxide is 99% at most, the sum of the selectivities of epoxy cyclohexane and cyclohexanediol which are reaction products is 97% at most, and the effect is remarkable.)

1. A method for catalyzing olefin epoxidation reaction by titanium-containing mesoporous molecular sieve comprises the following steps:

contacting an olefin, an oxidant, and optionally a solvent, with a titanium-containing mesoporous molecular sieve under olefin epoxidation conditions; wherein, the titanium-containing mesoporous molecular sieve comprises: the molecular sieve comprises a mesoporous molecular sieve, fluorine and titanium, wherein the molar ratio of the titanium to the fluorine to the mesoporous molecular sieve is 1: (0.1-10): (10-100), wherein the mesoporous molecular sieve is SiO₂And (6) counting.

2. The process according to claim 1, wherein the olefin is an alkene and/or a cycloalkene;

preferably, the olefin is C₃-C₁₈More preferably C₃-C₁₀The olefin of (a);

further preferably, the olefin is selected from at least one of propylene, butene and cyclohexene.

3. The method of claim 1, wherein the oxidizing agent is hydrogen peroxide;

preferably, the solvent is selected from water, C₁-C₆Alcohol of (1), C₃-C₈Ketone and C₂-C₆One or more of (a) nitrile(s).

4. The process according to any one of claims 1 to 3, wherein the catalyst to olefin mass ratio is 1:1 to 100, preferably 1: 2-20, more preferably 1: 7-20 parts of;

preferably, the molar ratio of olefin to oxidant is from 0.01 to 100: 1, more preferably 0.1 to 10: 1, more preferably 0.3 to 3: 1;

preferably, the mass ratio of the olefin to the solvent is 1 to 100: 100.

5. the process of any of claims 1-4, wherein the conditions of the olefin epoxidation conditions comprise: the temperature is 20-200 ℃, the pressure is 0.1-1MPa, and the reaction time is 0.1-16 hours;

preferably, the temperature is 30-100 ℃, the pressure is 0.1-0.8MPa, and the reaction time is 0.3-8 hours.

6. The method according to any one of claims 1 to 5, wherein the titanium-containing mesoporous molecular sieve has a molar ratio of titanium element, fluorine element and mesoporous molecular sieve of 1: (0.2-5): (40-75);

preferably, the mesoporous molecular sieve is selected from at least one of SBA-15, MCM-41, MCM-48, HMS, KIT-6 and MSU, more preferably SBA-15;

preferably, the titanium-containing mesoporous molecular sieve has a characteristic peak at the wavelength of 220-230nm as characterized by UV-Vis.

7. The method of claim 6, wherein the titanium-containing mesoporous molecular sieve is prepared by a method comprising:

(1) mixing a titanium source, a fluorine source and a silicon source to obtain a first material;

(2) mixing the first material with a mesoporous molecular sieve to obtain a second material;

(3) aging the second material;

(4) and drying and roasting the aged product.

8. The method of claim 6, wherein the titanium source is selected from TiCl₄、TiOSO₄、TiCl₃、TiF₄、H₂TiF₆And (NH)₄)₂TiF₆At least one of;

preferably, the fluorine source is selected from NH₄F. At least one of NaF, KF, and HF;

preferably, the silicon source is an organic silicon source and/or an inorganic silicon source;

further preferably, the silicon source is selected from H₂SiF₆、SiF₄、SiCl₄、(NH₄)₂SiF₆And ethyl orthosilicate.

9. The method of claim 7, wherein the molar ratio of the titanium source, the fluorine source, and the silicon source is 1: (0.1-10): (0.1-10), preferably 1: (0.2-5): (0.2-5), wherein the silicon source is SiO₂Counting;

preferably, the molar ratio of the titanium source to the mesoporous molecular sieve is 1: (10-100), more preferably 1: (20-60), wherein the mesoporous molecular sieve is SiO₂And (6) counting.

10. The method of claim 7, wherein the aging conditions of step (3) comprise: under the condition of stirring, the aging temperature is 20-100 ℃, and the aging time is 0.5-24 h;

preferably, the aging conditions include: aging at 20-80 deg.C for 0.5-18 h;

further preferably, the aging conditions include: aging at 25-70 deg.C for 1-12 h;

preferably, the calcination in step (4) is carried out at a temperature of 350-880 ℃, preferably 350-700 ℃, more preferably 400-600 ℃.

11. The method of claim 7, wherein the method further comprises: introducing acid to adjust the pH in the step (2); preferably, the acid is introduced in an amount such that the pH of the second material is 2-7, more preferably 3-6.5.

Technical Field

The invention relates to the field of olefin epoxidation, in particular to a method for catalyzing olefin epoxidation by a titanium-containing mesoporous molecular sieve.

Background

Corresponding epoxy products prepared by olefin epoxidation reaction have important positions in organic synthesis, medicine, pesticide, fine chemical preparation and the like. For example, epoxycyclohexane has a very active epoxy group in its molecular structure, so that it can react with amine, phenol, alcohol, carboxylic acid, etc. to produce a series of high value-added compounds, for example, it can be synthesized by using it as raw material: the pesticide is propargite; unsaturated resin with high hardness, high temperature resistance and acid and alkali resistance; novel, highly efficient photosensitive coatings and photosensitive adhesives; a crown ether; a polycarbonate; important fine chemicals are adipaldehyde, etc. In addition, the epoxy resin reactive diluent is an organic solvent with strong dissolving capacity and can be used as an epoxy resin reactive diluent.

The propylene oxide is mainly used for producing polyether polyol, propylene glycol, various nonionic surfactants and the like, wherein the polyether polyol is an important raw material for producing polyurethane foam, heat insulation materials, elastomers, adhesives, coatings and the like, and the various nonionic surfactants are widely applied to industries such as petroleum, chemical engineering, pesticides, textile, daily chemicals and the like. Meanwhile, propylene oxide is also an important basic chemical raw material. Propylene oxide is an important derivative of propylene, with about 7% of propylene being used for propylene oxide production each year. The production process mainly comprises a chlorohydrination method, a co-oxidation method (also called an indirect oxidation method) and a direct oxidation method. The predominant commercial processes for the worldwide production of propylene oxide today are the chlorohydrination process and the co-oxidation process, which in turn is divided into the ethylbenzene co-oxidation process and the isobutane co-oxidation process. In recent years, a cumene oxidation process and a hydrogen peroxide direct oxidation process have been successfully developed and successively realized for industrial production, and a direct oxidation process using oxygen as an oxidizing agent is also under development. The chlorohydrination process mainly comprises chlorohydrination of propylene, saponification of lime milk and product refining, and is characterized by mature production process, large elasticity of operation load, good selectivity and low requirement for the purity of the raw material propylene, thereby improving the safety of production and reducing construction investment. Because the investment of fixed assets is less, the product cost is lower, and the product has stronger cost competitiveness. The worldwide production of propylene oxide is now about 40% of the chlorohydrin process.

The chlorohydrin method has the defects of large water resource consumption, generation of a large amount of wastewater and waste residues, 40-50 tons of saponification wastewater containing chloride and more than 2 tons of waste residues when 1 ton of propylene oxide is produced, high temperature, high pH value, high chlorine content, high COD content and high suspended matter content, and is difficult to treat. Meanwhile, the chlorohydrin method also consumes a large amount of chlorine and lime raw materials with high energy consumption, chlorine and calcium are discharged in waste water and waste residues, and hypochlorous acid generated in the production process has serious corrosion to equipment. The co-oxidation method has the disadvantages of long process flow, various raw materials, high propylene purity requirement, high process operation under higher pressure, high equipment cost and high construction investment due to the adoption of alloy steel as the equipment material. Meanwhile, in the production of the propylene oxide by the co-oxidation method, the propylene oxide is only a coproduct with low yield, 2.2-2.5 tons of styrene or 2.3 tons of tert-butyl alcohol are co-produced for each ton of propylene oxide, and the mutual restriction factors of raw material sources and product sales are large and need to be properly solved.

The cumene oxidation process is actually an improvement over the co-oxidation process, and differs from the co-oxidation process mainly in that cumene is used instead of ethylbenzene, and is recycled without co-production. Because the process does not need auxiliary equipment required by co-production of styrene, the investment cost of the device is about 1/3 lower than that of the co-oxidation method, and corrosion-resistant equipment required by the chlorohydrin method process using chlorine gas is not required. The hydrogen peroxide direct oxidation method (HPPO method) is a new process for preparing propylene oxide by catalyzing and epoxidizing propylene with hydrogen peroxide (hydrogen peroxide), only generates propylene oxide and water in the production process, has simple process flow, high product yield, no other co-products and basically no pollution, and belongs to an environment-friendly clean production system. The direct hydrogen peroxide oxidation process is currently developed and industrially popularized by Degussa in conjunction with Uhde, dow chemical and BASF, respectively.

At present, although the titanium-containing molecular sieve material is used for catalyzing the epoxidation reaction of micromolecule olefin or cycloolefin by a hydrogen peroxide direct oxidation method, the existing microporous titanium-containing material has a plurality of defects for catalyzing the epoxidation reaction of larger olefin molecules due to the influence of molecular diffusion, so that the development of a new titanium-containing Ti-SBA-15 molecular sieve with a larger pore diameter has important significance.

Disclosure of Invention

The invention aims to overcome the defects of the prior art that a titanium-containing material has a plurality of defects for catalyzing the epoxidation reaction of larger olefin molecules, and provides a method for catalyzing the epoxidation reaction of olefin by using a titanium-containing mesoporous molecular sieve.

In order to achieve the above object, the present invention provides a method for catalyzing olefin epoxidation reaction by titanium-containing mesoporous molecular sieve, which comprises:

contacting an olefin, an oxidant, and optionally a solvent, with a titanium-containing mesoporous molecular sieve under olefin epoxidation conditions; wherein, the titanium-containing mesoporous molecular sieve comprises: the molecular sieve comprises a mesoporous molecular sieve, fluorine and titanium, wherein the molar ratio of the titanium to the fluorine to the mesoporous molecular sieve is 1: (0.1-10): (10-100), wherein the mesoporous molecular sieve is SiO₂And (6) counting.

Preferably, the titanium-containing mesoporous molecular sieve has a characteristic peak at the wavelength of 220-230nm as characterized by UV-Vis.

Preferably, the preparation method of the titanium-containing mesoporous molecular sieve comprises the following steps:

(1) mixing a titanium source, a fluorine source and a silicon source to obtain a first material;

(2) mixing the first material with a mesoporous molecular sieve to obtain a second material;

(3) aging the second material;

(4) and drying and roasting the aged product.

The method for catalyzing the olefin epoxidation reaction by the titanium-containing mesoporous molecular sieve is clean and efficient, has few byproducts, can realize the epoxidation reaction of olefin or cycloolefin with larger molecular weight, and has remarkable economic benefit and social benefit. The titanium-containing mesoporous molecular sieve has high activity and high effective utilization rate of hydrogen peroxide, and is favorable for obtaining high catalytic reaction rate and product selectivity. The results of the examples show that in the olefin epoxidation reaction provided by the invention, the conversion rate of the reactant and the selectivity of the target product are high, wherein the conversion rate of cyclohexene is 99% at most, the utilization rate of hydrogen peroxide is 99% at most, the sum of the selectivities of the epoxycyclohexane and cyclohexanediol as the reaction products is 97% at most, and the effect is remarkable.

Drawings

FIG. 1 shows the UV-Vis characterization spectra of Ti-SBA-15 mesoporous molecular sieve C-1 prepared in preparation example 1 and Ti-SBA-15 mesoporous molecular sieve X prepared in preparation comparative example 1.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The invention provides a method for catalyzing olefin epoxidation reaction by titanium-containing mesoporous molecular sieve, which comprises the following steps:

contacting an olefin, an oxidant, and optionally a solvent, with a titanium-containing mesoporous molecular sieve under olefin epoxidation conditions; wherein, the titanium-containing mesoporous molecular sieve comprises: mesoporous molecular sieve, fluorine element, titaniumThe mol ratio of the elements, the fluorine elements and the mesoporous molecular sieve is 1: (0.1-10): (10-100), wherein the mesoporous molecular sieve is SiO₂And (6) counting.

According to the invention, the olefin may be an alkene, a cycloalkene or a mixture of both.

According to the invention, preferably, the olefin is C₃-C₁₈Preferably C₃-C₁₀The olefin of (1).

Hereinafter, some terms in the present invention will be explained in detail:

said "C₃-C₁₈The "olefin" of (a) means an olefin having a total number of carbon atoms of 3 to 18, and includes a linear olefin, a branched olefin and a cyclic olefin, and specifically, for example, a linear olefin, a branched olefin or a cyclic olefin having a total number of carbon atoms of 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18.

According to a preferred embodiment of the present invention, the olefin is at least one selected from the group consisting of propylene, butene and cyclohexene, and is more preferably cyclohexene. The method provided by the invention is particularly suitable for the oxidation of cyclohexene, and has higher reaction activity and selectivity.

In the present invention, the oxidizing agent is selected from a wide range as long as the object of the present invention can be achieved. Preferably, the oxidizing agent is hydrogen peroxide. Further preferably, the oxidizing agent is aqueous hydrogen peroxide (hydrogen peroxide). Due to the unstable property of the high-concentration hydrogen peroxide, potential safety hazards exist in the processes of production, storage, transportation and use, and the cost is high. More preferably, the oxidant is hydrogen peroxide with the concentration of 10-60 wt%.

According to the method for the olefin epoxidation reaction provided by the invention, the optional solvent means that the solvent can be introduced or not introduced when the olefin and the oxidant are contacted with the titanium-containing mesoporous molecular sieve. Preferably, a solvent is introduced in the above-mentioned contacting.

The solvent used in the process for the epoxidation of an olefin is not particularly limited in the present invention, and preferably, the solvent is selected from the group consisting of water and C₁-C₆Alcohol of (2)、C₃-C₆Ketone and C₂-C₆One or more of (a) nitrile(s). In the present invention, the term "C" is used₁-C₆The alcohol of (1) represents an alcohol having a total number of carbon atoms of 1 to 6, including a linear alcohol, a branched alcohol or a cyclic alcohol, and the "C" is₃-C₆The "ketone" of (a) represents a ketone having a total number of carbon atoms of 3 to 6, including a straight chain ketone, a branched chain ketone or a cyclic ketone, and the "C" is₂-C₆The "nitrile" of (a) means a nitrile having a total number of carbon atoms of 2 to 6, and includes a straight chain nitrile, a branched chain ketone or a cyclic nitrile. Further preferably, the solvent is selected from at least one of water, methanol, ethanol, acetonitrile, propionitrile, acetone, t-butanol, n-propanol, isopropanol and sec-butanol.

In the present invention, the amount of the catalyst is selected from a wide range, and preferably, the mass ratio of the catalyst to the olefin is 1:1 to 100, preferably 1: 2-20, more preferably 1: 7-20.

In the present invention, the amount of the oxidant is selected from a wide range, and preferably, the molar ratio of the olefin to the oxidant is 0.01 to 100: 1, more preferably 0.1 to 10: 1, more preferably 0.3 to 3: 1.

in the present invention, the amount of the solvent is selected from a wide range, and preferably, the mass ratio of the olefin to the solvent is 1 to 100: 100, more preferably 1 to 20: 100.

according to the present invention, preferably, the conditions of the olefin epoxidation conditions comprise: the temperature is 20-200 ℃, the pressure is 0.1-1MPa, and the reaction time is 0.1-16 h.

Further preferably, the conditions of the olefin epoxidation conditions comprise: the temperature is 30-100 ℃, the pressure is 0.1-0.8MPa, and the reaction time is 0.3-8 hours. In this preferred case, the epoxidation of the olefin is more advantageously carried out.

According to the present invention, preferably, the mesoporous molecular sieve is selected from at least one of SBA-15, MCM-41, MCM-48, HMS, KIT-6 and MSU, more preferably SBA-15. The adoption of the optimal selection mode is more beneficial to improving the catalytic performance of the titanium-containing mesoporous molecular sieve.

According to the invention, XRF method can be adopted to measure the molar ratio of titanium element, fluorine element and mesoporous molecular sieve.

Preferably, the titanium-containing mesoporous molecular sieve has a characteristic peak at the wavelength of 220-230nm as characterized by UV-Vis. The characteristic peak indicates that the metallic titanium element in the titanium-containing mesoporous molecular sieve of the invention has a specific occurrence state. The molecular sieve adopting the preferred embodiment has better reaction performance for catalyzing olefin epoxidation reaction.

In the invention, the mesoporous molecular sieve can be obtained by commercial products or can be prepared by the existing method.

According to a preferred embodiment of the present invention, the molar ratio of the metallic titanium element, the fluorine element and the mesoporous molecular sieve is 1: (0.2-5): (40-75). In such a preferable ratio, it is more advantageous to increase the reaction conversion rate and the product selectivity.

According to the olefin epoxidation method provided by the invention, the aim of the invention can be achieved only by adopting the titanium-containing mesoporous molecular sieve, the selection range of the preparation method of the titanium-containing mesoporous molecular sieve is wide, and preferably, the preparation method of the titanium-containing mesoporous molecular sieve comprises the following steps:

(1) mixing a titanium source, a fluorine source and a silicon source to obtain a first material;

(2) mixing the first material with a mesoporous molecular sieve to obtain a second material;

(3) aging the second material;

(4) and drying and roasting the aged product.

The titanium source can be selected from a wide range as long as the titanium source can provide metallic titanium, such as a titanium-containing soluble salt. Preferably, the titanium source is selected from TiCl₄、TiOSO₄、TiCl₃、TiF₄、H₂TiF₆And (NH)₄)₂TiF₆At least one of (1).

In the present invention, the fluorine source may be selected from a wide range as long as it can provide fluorine, for example, hydrofluoric acid and/or a fluorine-containing soluble salt. Preferably, the fluorine source is selected from NH₄F. At least one of NaF, KF and HF.

In the present invention, the term "soluble" means that the solvent can be dissolved directly or dissolved in a solvent under the action of a cosolvent.

The silicon source selection range of the invention is wider, and the silicon source can be various silicon sources which are conventionally used in the field. Specifically, the silicon source is an organic silicon source and/or an inorganic silicon source. Preferably, the silicon source is selected from H₂SiF₆、SiF₄、SiCl₄、(NH₄)₂SiF₆And ethyl orthosilicate. The preferred embodiment is more beneficial to improving the performance of the prepared molecular sieve for catalyzing olefin epoxidation reaction.

According to the present invention, the fluorine source and the silicon source may be introduced in the form of a solution (e.g., an aqueous solution).

According to the invention, the mixing process in step (1) may optionally further include a solvent, if the titanium source, the fluorine source and the silicon source can satisfy the requirement of uniform mixing, i.e. the solvent does not need to be introduced, and the solvent (preferably water) needs to be introduced otherwise. In the present invention, the amount of the solvent to be introduced is not particularly limited, and may be appropriately selected depending on the amounts of the titanium source, the fluorine source and the silicon source to be introduced, as long as the requirement of sufficient mixing can be satisfied.

According to a preferred embodiment of the present invention, the step (1) comprises: and mixing a titanium source, a fluorine source, a solvent and a silicon source to obtain the first material.

In the present invention, the mixing in the step (1) is not particularly limited, and may be performed under stirring conditions or ultrasonic conditions. Preferably, the mixing in step (1) is carried out under ultrasound, which is more favorable for material mixing.

According to a specific embodiment of the present invention, the titanium source, the fluorine source and the mesoporous molecular sieve are used in such amounts that the molar ratio of the titanium element, the fluorine element and the mesoporous molecular sieve in the obtained titanium-containing mesoporous molecular sieve is 1: (0.1-10): (10-100), preferably 1: (0.2-5): (40-75). It should be noted that, if the titanium source and the silicon source contain F element during the preparation process, which can provide part of F element, the amount of the fluorine source can be reduced accordingly. The skilled person will know how to select the titanium source, the fluorine source and the ratio of the amount of mesoporous molecular sieve based on the above disclosure.

According to the present invention, it is preferable that the molar ratio of the titanium source, the fluorine source and the silicon source is 1: (0.1-10): (0.1-10), preferably 1: (0.2-5): (0.2-5), wherein the silicon source is SiO₂And (6) counting.

According to the method provided by the invention, the selection of the mesoporous molecular sieve is as described above, and details are not repeated here.

According to the present invention, preferably, the molar ratio of the titanium source to the mesoporous molecular sieve is 1: (10-100), more preferably 1: (20-60), wherein the mesoporous molecular sieve is SiO₂And (6) counting.

In the present invention, the mixing in the step (2) is not particularly limited, and may be performed under stirring conditions as long as the mesoporous molecular sieve and the first material are uniformly mixed.

According to the present invention, preferably, the aging conditions of step (3) include: aging at 20-100 deg.C for 0.5-24 hr; in order to further optimize the aging effect, it is preferable that the aging in step (3) is performed under stirring conditions. The stirring is preferably carried out using a magnetic stirrer.

Preferably, the aging conditions include: the aging temperature is 20-80 ℃, and the aging time is 0.5-18 h.

Further preferably, the aging conditions include: the aging temperature is 25-70 ℃, and the aging time is 1-12 h. Under the preferable condition, the prepared titanium-containing mesoporous molecular sieve is used for catalyzing olefin epoxidation reaction, and high material conversion rate and product selectivity can be obtained.

According to an embodiment of the present invention, the method may further include: filtering and washing the aged product to obtain an aged product before the drying in the step (4). The filtration and washing are all operations well known to those skilled in the art, and the present invention is not particularly limited.

The conditions for the drying in step (4) are particularly limited in the present invention, and may be those well known to those skilled in the art. For example, the drying conditions may include: the temperature is 80-180 ℃ and the time is 1-20 hours.

Preferably, the calcination in step (4) is carried out at a temperature of 300-880 ℃, preferably 300-700 ℃, more preferably 400-600 ℃. The selection range of the roasting time is wide, and the roasting time is preferably 1 to 10 hours, more preferably 2 to 6 hours.

According to the present invention, preferably, the method further comprises: introducing acid to adjust the pH in the step (2). It should be noted that, under this preferred scheme, the pH of the material to be aged (the second material) can be adjusted, which is more beneficial to improving the catalytic performance of the prepared molecular sieve.

The acid may be various acids conventionally used in the art as long as it can function to adjust the pH, and for example, the acid may be at least one of nitric acid, hydrochloric acid, acetic acid, and carbonic acid.

In the traditional preparation method, under the acidic condition, the hydrolysis rate of the titanium source is greater than that of the silicon source, and the titanium source is hydrolyzed into TiO before being combined with the mesoporous molecular sieve₂Resulting in failure to insert into the molecular sieve framework. The titanium-containing mesoporous molecular sieve provided under the optimal condition of the invention overcomes the defects, the addition of the fluorine source influences the occurrence state of the metal titanium atoms, the formation of chemical bonds between the metal titanium atoms and the oxygen atoms is reduced, and TiO is avoided₂And (4) generating. The method of the invention is more beneficial to the direct synthesis of the titanium-containing mesoporous molecular sieve, the efficiency of inserting the metal titanium into the framework of the molecular sieve is high, and the molecular sieve has better catalytic performance when being used for olefin epoxidation reaction.

Preferably, the pH of the second material is 1 to 7, more preferably 3 to 6.5. In the preferable condition, the conversion rate and the product selectivity of the titanium-containing mesoporous molecular sieve are improved.

The present invention will be described in detail below by way of examples.

The reagents used in the following examples are all commercially available chemically pure reagents.

Hydrochloric acid, silicon tetrachloride, Tetraethoxysilane (TEOS), titanium trichloride and titanium tetrachloride are analytically pure and purchased from chemical reagents of national medicine group, Inc.;

the SBA-15 mesoporous molecular sieve is produced by Hunan Jianchang petrochemical company; MCM-41, HMS, KIT-6 and MCM-48 all-silicon mesoporous molecular sieves were synthesized according to the monograph (Zhao Dongyuan et al, ordered mesoporous molecular sieve materials [ M ]. higher education publishers, 2012).

The UV-Vis characterization map of the titanium-containing mesoporous molecular sieve prepared in the preparation example is obtained by characterizing an instrument with the model number of UV-visble550 purchased from JASCO company; the molar ratio of the metallic titanium element, the fluorine element and the mesoporous molecular sieve is measured by an XRF method.

The room temperature refers to 25 ℃ without special limitation; the pressures are all in absolute terms.

In the following preparation examples, the silicon source and the molecular sieve are both used in SiO₂And (6) counting.

Preparation example 1

(1) Mixing a metal titanium source, a fluorine source and a silicon source in an ultrasonic environment to form a colorless transparent solution;

(2) adding the colorless transparent solution into a suspension containing the SBA-15 molecular sieve which is continuously stirred, and then adding 0.1mol/L hydrochloric acid to adjust the pH value to 6.1-6.2; the dosage proportion and the types of the metal titanium source, the fluorine source, the silicon source and the mesoporous molecular sieve are listed in table 1;

(3) continuously stirring and aging the suspension obtained in the step (2) for 2 hours at the temperature of 40 ℃;

(4) and (4) sequentially filtering and washing the product obtained in the step (3) to obtain an aged product, drying at 120 ℃ for 4 hours, and roasting at 550 ℃ for 3 hours to obtain the Ti-SBA-15 mesoporous molecular sieve C-1.

FIG. 1 shows a UV-Vis characterization spectrum of Ti-SBA-15 mesoporous molecular sieve C-1, and it can be seen from FIG. 1 that the molecular sieve has a characteristic peak at a wavelength of 220-230 nm. The characteristic peak positions of the titanium-containing mesoporous molecular sieve are characterized by UV-Vis and are listed in Table 2.

Preparation examples 2 to 10

Titanium-containing mesoporous molecular sieves C-2 to C-10 were prepared according to the method of preparation example 1, except that the ratios and kinds of the metal titanium source, fluorine source, silicon source and mesoporous molecular sieve used in step (1) and the aging conditions in step (3) were different, and the specific conditions of each preparation example are listed in Table 1.

The characteristic peak positions of the titanium-containing mesoporous molecular sieves C-2 to C-10, the molar ratios of the titanium metal element, the fluorine element and the mesoporous molecular sieves are shown in Table 2.

TABLE 1

TABLE 2

Preparation of comparative example 1

The Ti-SBA-15 mesoporous molecular sieve material is directly synthesized according to the method reported in the Applied Catalysis A, General,2004,273(1-2), 185-191. TEOS and titanium trichloride are respectively used as a silicon source and a metal titanium source, a triblock copolymer P123 (molecular weight is 5800) is used as a structure directing agent, a concentrated hydrochloric acid aqueous solution is used as an acid source, and the specific synthesis steps are as follows:

(1) 2g P123 was dissolved in 60ml of hydrochloric acid solution at pH 5;

(2) after 4.25g of tetraethyl orthosilicate (TEOS) had been prehydrolyzed at 40 ℃ for a period of time, 0.02g of TiCl was added to the acidic solution with vigorous stirring₃Mixing with 2ml hydrogen peroxide solution, and stirring for 24 hours;

(3) the resulting mixture was statically aged at 60 ℃ for 24 hours;

(4) the resulting aged product was recovered, washed, and dried at 100 ℃ overnight. Calcining for 6h at 550 ℃ in the air to obtain the Ti-SBA-15 mesoporous molecular sieve X.

FIG. 1 shows a UV-Vis characterization spectrum of Ti-SBA-15 mesoporous molecular sieve X, and it can be seen from FIG. 1 that the molecular sieve has no characteristic peak at the wavelength of 220-230 nm. The characteristic peak positions of the Ti-SBA-15 mesoporous molecular sieve X are represented by UV-Vis in Table 2.

Preparation of comparative example 2

Ti-MCM-41 was synthesized by microwave hydrothermal method according to the method reported in Journal of Environmental Sciences,2016,44: 76-87. Cationic surfactant Cetyl Trimethyl Ammonium Bromide (CTAB) is used as template agent. Titanium isopropoxide and sodium silicate (Na)₂SiO₃) The method is used as a metal titanium source and a silicon source respectively, and comprises the following specific synthetic steps:

(1) 4.25g CTAB and 5.32g Na were added₂SiO₃Dissolving the two solutions in 30mL and 15mL of deionized water respectively, mixing the two solutions, and then stirring vigorously for 30 minutes at room temperature;

(2) adding 0.45g of titanium isopropoxide into the mixture, stirring for 180min, and adjusting the pH value of the mixed solution to 9.5-10.0 by using 0.1mol/L hydrochloric acid;

(3) heating the mixed solution at 100 ℃ for 180 minutes under the 120W microwave hydrothermal condition, then washing with deionized water and drying;

(4) and sintering the obtained product at 823K for 6 hours to obtain the Ti-MCM-41 molecular sieve Y.

The characteristic peak positions of Ti-MCM-41 molecular sieve Y are shown in Table 2 by the characterization of UV-Vis.

Preparation of comparative example 3

Neutral S was used according to the method reported in the Journal of Molecular Catalysis A: Chemical,2015,397:26-35⁰I⁰Synthesizing the HMS-Ti molecular sieve material by a template method. The process is based on a neutral primary amine surfactant S⁰(dodecylamine) with a neutral inorganic precursor I⁰(tetraethoxysilane: TEOS) hydrogen bond and self-assembly, and mesitylene and tetrabutyl orthotitanate are respectively used as Ti⁴⁺Cationic swelling agent and precursor, filtering the product obtained by the reaction and washing the product with distilled water. Then dried at room temperature for 24h and at 100 ℃ for 2h, and then calcined in air at 550 ℃ for 3.5h to obtain the HMS-Ti molecular sieve Z.

The characteristic peak positions of the HMS-Ti molecular sieve Z characterized by UV-Vis are listed in Table 2.

Example 1

This example is used to illustrate the olefin epoxidation reaction catalyzed by the titanium-containing mesoporous molecular sieve provided by the present invention, and the specific steps include:

(1) adding the catalyst C-1 obtained in the preparation example 1, cyclohexene and a solvent methanol into a three-neck flask, and mixing under magnetic stirring to obtain a mixed material; the weight ratio of the catalyst to the cyclohexene to the solvent is 1:20: 100; the specific material ratios and conditions are listed in table 3.

(2) After the temperature is raised to 50 ℃ by electric heating, introducing a 30 wt% aqueous hydrogen peroxide solution into the mixture, wherein the reaction time is 5h, and the molar ratio of cyclohexene to hydrogen peroxide is 1: 1; the reaction temperature was kept at 50 ℃; the specific material ratios and conditions are listed in table 3.

The reactants and the products are analyzed by gas chromatography (Agilent 6890N, HP-5 capillary column 30m 0.25mm 0.25 μm), an internal standard method is adopted for quantification, the content of hydrogen peroxide, cyclohexene oxide and cyclohexanediol in the reaction products is measured, and the data of the hydrogen peroxide utilization rate, the cyclohexene conversion rate and the selectivity of the products cyclohexene oxide and cyclohexanediol are respectively obtained by calculation. The data results are shown in Table 4.

Wherein: the cyclohexene conversion rate is (amount of the raw material cyclohexene substance-amount of the cyclohexene substance remaining after the reaction)/amount of the raw material cyclohexene substance x 100%;

the epoxycyclohexane product selectivity is the amount of epoxycyclohexane substance/(amount of cyclohexene substance as raw material-amount of cyclohexene substance remaining after reaction) × 100%;

the product selectivity of cyclohexanediol is equal to the mass of cyclohexanediol/(the mass of cyclohexene material as the raw material-the mass of cyclohexene material remaining after the reaction) × 100%;

H₂O₂utilization rate ═ initial H₂O₂Amount of substance-remaining H after reaction₂O₂Amount of material)/initial H₂O₂Amount of substance × 100%.

Examples 2 to 18

Following the procedure of example 1, except that the specific material ratios and conditions were varied, the specific material ratios and conditions are shown in Table 3, and the results of the calculated hydrogen peroxide utilization, cyclohexene conversion, and product cyclohexene oxide and cyclohexanediol selectivities are shown in Table 4.

Examples 19 to 27

The procedure of example 1 was followed, except that the catalyst C-1 was replaced with the same amounts of the catalysts C-2 to C-10, respectively. The results of the data on hydrogen peroxide utilization, cyclohexene conversion, product cyclohexene oxide and cyclohexanediol selectivity are presented in table 4.

Comparative examples 1 to 3

The procedure of example 1 was followed except that the catalysts were replaced with X, Y and Z obtained in preparation of comparative examples 1-3, respectively, and the results of the data calculated for hydrogen peroxide utilization, cyclohexanone conversion and cyclohexanone oxime selectivity are shown in Table 4.

TABLE 3

TABLE 4

The method for catalyzing the olefin epoxidation reaction can realize the epoxidation reaction of olefin or cycloolefin with larger molecular weight, and has obvious economic benefit and social benefit. The results of the examples show that when cyclohexene catalytic epoxidation is performed in the method provided by the invention, the conversion rate of the reactant and the selectivity of the target product are higher, wherein the conversion rate of cyclohexene can reach 99% at most, the utilization rate of hydrogen peroxide can reach 99% at most, the sum of the selectivities of cyclohexene oxide and cyclohexanediol which are reaction products can reach 97% at most, and the effect is remarkable.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.