Double-titanium-site high-performance epoxidation catalyst as well as preparation method and application thereof

Abstract

The invention discloses a double-titanium-site high-performance epoxidation catalyst as well as a preparation method and application thereof. The catalyst is prepared by a method comprising the following steps: (1) mixing a template agent and formate in a solvent to obtain a template solution; (2) adding a titanium source, so that formate adsorbs a pair of titanium cores to form a Ti (III)-Ti (IV) double-titanium core precursor; (3) adding a silicon source, and crystallizing by a hydrothermal method, so that titanium grows in a double-core structure; and (4) washing and roasting to obtain the double-titanium core molecular sieve catalyst.

Description

Technical Field

[0001] The present invention relates to the field of catalysts, and in particular to a catalyst, a preparation method and application thereof. Background Art

[0002] Epichlorohydrin (ECH), also known as epichlorohydrin, is an important organic raw material commonly used in the production of industrial products such as glycerol, epoxy resin, and epichlorohydrin rubber. Its annual output has been growing steadily and has high economic value. The main methods for producing epichlorohydrin in traditional industries include the glycerol method, the propylene high-temperature chlorination method, and the allyl alcohol method. However, these methods have the disadvantages of high cost, complex process, and low atomic economy. The three wastes produced by them can also cause serious environmental pollution. Therefore, it is of great practical significance to develop a green, efficient, and highly economical method for synthesizing epichlorohydrin.

[0003] In view of the above problems, the preparation of epichlorohydrin by hydrogen peroxide has the advantages of simple process and low cost. Its raw material hydrogen peroxide will only produce water after the epoxidation reaction, which is superior in terms of green environmental protection. At present, the catalysts developed for catalytic hydrogen peroxide epoxidation to epichlorohydrin mainly include molecular sieve catalysts, molybdenum catalysts and tungsten heteropolyacid catalysts. Among them, TS-1 molecular sieve is a mature olefin epoxidation catalyst. Its annual output of catalytic production of propylene oxide reaches 10,000 tons. It also has excellent catalytic effect and selectivity for the preparation of epichlorohydrin by hydrogen peroxide. The high catalytic activity of TS-1 comes from its unique Ti-Ti binuclear site. The synergistic effect between the two titanium atoms enables the epoxidation reaction of olefins to proceed through a reaction pathway with lower activation energy. Among them, the key oxygen transfer transition state is similar to the epoxidation reaction of olefins by peroxyacids (Nature, volume 586, pages 708–713 (2020)). Constructing more dual titanium core sites is the key to improving the reaction performance of the catalyst.

[0004] CN 112375047B reported the use of self-made TS-1 titanium silicon molecular sieve catalyst to catalyze the epoxidation of 3-chloropropylene with hydrogen peroxide to produce epichlorohydrin. The hydrogen peroxide conversion rate can reach 99.2%, and the epichlorohydrin selectivity can reach 98.9%, but there are still disadvantages such as low reaction space velocity and many types of by-products.

[0005] Therefore, it is of great significance to develop a new and improved catalyst. Summary of the invention

[0006] The purpose of the present application is to provide a molecular sieve catalyst with double titanium sites. The catalyst can reduce the activation energy of the epoxidation reaction, accelerate the reaction rate, and can produce epichlorohydrin in large quantities at a faster space velocity. At the same time, since the residence time of the raw material in the reactor is shortened, the content of alkenyl ether by-products is greatly reduced, reducing the subsequent separation cost.

[0007] On the one hand, the present application provides a molecular sieve catalyst, which is prepared by a method comprising the following steps:

[0008] (1) mixing a template agent and a formate in a solvent to obtain a template solution;

[0009] (2) adding a titanium source so that formate adsorbs a pair of titanium cores to form a Ti(III)-Ti(IV) dual titanium core precursor;

[0010] (3) Adding silicon source and hydrothermal crystallization to grow titanium with a dual-core structure;

[0011] (4) washing and calcining to obtain a double titanium core molecular sieve catalyst.

[0012] On the other hand, the present application provides a method for preparing a molecular sieve catalyst, the method comprising the following steps:

[0013] (1) mixing a template agent and a formate in a solvent to obtain a template solution;

[0014] (2) adding a titanium source so that formate adsorbs a pair of titanium cores to form a Ti(III)-Ti(IV) dual titanium core precursor;

[0015] (3) Adding silicon source and hydrothermal crystallization to grow titanium with a dual-core structure;

[0016] (4) washing and calcining to obtain a double titanium core molecular sieve catalyst.

[0017] In another aspect, the present application provides a method for preparing epichlorohydrin by epoxidizing allyl chloride, the method comprising reacting allyl chloride, hydrogen peroxide, a solvent and the molecular sieve catalyst according to the present disclosure.

[0018] In one embodiment of the present invention, the molar ratio of hydrogen peroxide to allyl chloride is 1:1-1:4.

[0019] In one embodiment of the present invention, the reaction temperature is 15-40°C.

[0020] In another aspect, the present application provides a use of the molecular sieve catalyst described in the present application in catalyzing the epoxidation of 3-chloropropylene with hydrogen peroxide to produce epichlorohydrin.

[0021] The advantages of this application are:

[0022] (1) Compared with the conventional titanium silicon molecular sieve catalyst, the active metal of the synthesized dual titanium core molecular sieve catalyst of the present invention is dispersed more in the form of dual cores. More dual titanium cores can provide more low activation energy reaction sites for the olefin epoxidation reaction, thereby promoting the reaction process and accelerating the reaction rate, and epichlorohydrin can be produced in large quantities at a faster space velocity.

[0023] (2) Since the residence time of the raw materials in the reactor is shortened, the content of alkenyl ether byproducts is greatly reduced, which reduces the subsequent separation cost. For example, the catalyst can accommodate a faster reaction space velocity when catalyzing the epoxidation of 3-chloropropylene with hydrogen peroxide to produce epichlorohydrin, with high reaction conversion rate, good selectivity, and greatly reduced content of alkenyl ether byproducts. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a transmission scanning electron microscope (TSEM) image of catalyst C1 obtained in Example 1. DETAILED DESCRIPTION

[0025] "Scope" disclosed herein is defined in the form of lower limit and upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The scope defined in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a particular parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0026] In this application, unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined with each other to form a new technical solution.

[0027] In this application, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0028] In the present application, unless otherwise specified, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0029] In this application, unless otherwise specified, the terms "include" and "comprising" mentioned herein may be open-ended or closed-ended. For example, the terms "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0030] In the description of this article, it should be noted that, unless otherwise specified, "above" and "below" are inclusive of the number itself, and "several" in "one or several" means two or more.

[0031] In the description herein, unless otherwise specified, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0032] Herein, unless otherwise specified, percentage (%) or part refers to percentage by weight or part by weight relative to the composition.

[0033] Herein, if there is no contrary description, the sum of the contents of the various components in the composition is 100%.

[0034] Herein, if there is no contrary description, the sum of the parts of each component in the composition may be 100 parts by weight.

[0035] In this context, unless otherwise specified, "a combination thereof" means a multi-component mixture of the elements described, for example a mixture of two, three, four and up to the maximum possible multi-component mixture.

[0036] If not specifically stated, the terms "a" or "an" used in the present specification means "at least one".

[0037] Herein, unless otherwise stated, all reactions are carried out at normal temperature and pressure.

[0038] In this document, unless otherwise specified, the terms "TS-1 catalyst" or "TS-1 molecular sieve catalyst" or "TS-1 titanium silicon molecular sieve catalyst" have the same meaning, all of which refer to molecular sieve catalysts used to catalyze the epoxidation reaction of allyl chloride, having a three-dimensional pore structure represented by ZSM-5, and consisting of zigzag channels and elliptical straight channels intersecting therewith.

[0039] As used herein, unless otherwise specified, an "aprotic solvent" is a solvent that cannot donate a proton in a reaction system, including but not limited to acetonitrile, DMF, DMI, DMSO, 1,4-dioxane, tetrahydrofuran, toluene, and the like.

[0040] The present invention develops a molecular sieve catalyst with dual titanium sites. Through hydrogen bonding and other interaction forces, formate is used to locally adsorb two molecules of titanium centers restricted by caged chelating ligands; and a special template is selected to enrich formate on the proton sites of the template, so that the active titanium grows in a binuclear form, thereby constructing more Ti-Ti binuclear sites. The catalyst can reduce the activation energy of the epoxidation reaction, accelerate the reaction rate, and can mass-produce epichlorohydrin at a faster space velocity. At the same time, since the residence time of the raw material in the reactor is shortened, the content of alkenyl ether byproducts is greatly reduced, reducing the subsequent separation cost.

[0041] On the one hand, the present application provides a molecular sieve catalyst, which is prepared by a method comprising the following steps:

[0042] (1) mixing a template agent and a formate in a solvent to obtain a template solution;

[0043] (2) adding a titanium source so that formate adsorbs a pair of titanium cores to form a Ti(III)-Ti(IV) dual titanium core precursor;

[0044] (3) Adding silicon source and hydrothermal crystallization to grow titanium with a dual-core structure;

[0045] (4) washing and calcining to obtain a double titanium core molecular sieve catalyst.

[0046] Step (1) The template and the formate are mixed in a solvent, the purpose of which is to make the formate aggregate on the proton sites of the template to provide adsorption points for the Ti-Ti dual core. Specifically, the template and the formate are mixed in a solvent as follows: the template and the formate are dissolved in water, stirred at a certain temperature for a certain time, and a template solution is obtained.

[0047] Preferably, in step (1), the template is selected from one or more organic amines substituted by one or more hydroxyl groups, quaternary ammonium salts substituted by one or more hydroxyl groups or amino groups. Preferably, the template is selected from one or more C1-C6 organic amines substituted by one or more hydroxyl groups, tetraalkylammonium halide salts substituted by one or more hydroxyl groups or amino groups. More preferably, the template is selected from tris(hydroxyC1-6 alkyl)C1-6 alkylammonium halide, tris(aminoC1-6 alkyl)C1-6 alkylammonium halide, di- (Hydroxy C1-6 alkyl) di-C1-6 alkyl ammonium halide, di-(amino C1-6 alkyl) di-C1-6 alkyl ammonium halide, (hydroxy C1-6 alkyl) tri-C1-6 alkyl ammonium halide, (amino C1-6 alkyl) tri-C1-6 alkyl ammonium halide, ethanolamine, diethanolamine, diglycolamine, diisopropanolamine, methyldiethanolamine, triethanolamine one or more, more preferably, the template is selected from tris (2-hydroxyethyl) propyl ammonium chloride, tris (2-hydroxyethyl) propyl ammonium bromide one or more;

[0048] Preferably, in step (1), the formate is selected from one or more of alkali metal formates, alkaline earth metal formates, formates of IIIA metals, and ammonium formate. Preferably, the formate is selected from one or more of sodium formate, potassium formate, magnesium formate, calcium formate, aluminum formate, and ammonium formate, or the formate is selected from one or more of sodium formate and potassium formate.

[0049] Preferably, in step (1), the solvent is water;

[0050] In the present application, in the above step (1), the amount of the template, formate and solvent (preferably water) is conventional, and the specific amount can be reasonably determined by a person skilled in the art. Preferably, in step (1), the molar ratio of the template to formate is 1:(0.03-0.45), more preferably 1:(0.035-0.4). Preferably, in step (1), the molar ratio of the template, formate and solvent (preferably water) is 1:(0.03-0.45):(20-500), preferably 1:(0.035-0.4):(100-200).

[0051] Preferably, in step (1), the mixing temperature is 10-45°C or 20-40°C.

[0052] Preferably, in step (1), the stirring time is 0.5 to 12 h or 1 to 8 h.

[0053] By premixing the template with formate, the formate can be enriched near the proton site of the template through hydrogen bonding effect or ionic effect.

[0054] The step (2) of adding a titanium source is intended to allow formate to adsorb a pair of titanium cores to form a Ti(III)-Ti(IV) dual titanium core precursor. Specifically, the titanium source can be added as follows: dissolving the titanium source in a solvent, adding the solution to the template solution in step (1), and adsorbing the solution under stirring at a certain temperature for a certain period of time;

[0055] Preferably, in step (2), the titanium source is L1-TiHal, wherein Hal is a halogen, such as F, Cl or Br, preferably L1-TiCl. The complex can be synthesized by reacting titanium trihalide (preferably titanium trichloride) with ligand L1 in tetrahydrofuran. Ligand L1 has the following structure:

[0056]

[0057] Wherein the substituent R1 is hydrogen or C 1-6 Alkyl, preferably H, methyl or tert-butyl, more preferably methyl; wherein the substituent R2 is hydrogen or C 1-6 Alkyl, preferably H, methyl or tert-butyl, more preferably methyl;

[0058] Preferably, in step (2), the solvent used is an organic solvent capable of dissolving the titanium source, preferably, the solvent used is an aprotic solvent, preferably, the solvent used is selected from one or more of tetrahydrofuran, dioxane, and toluene;

[0059] Preferably, in step (2), the molar concentration of the titanium source in the solvent is 5 to 20%, preferably 10 to 15%.

[0060] Preferably, in step (2), the molar ratio of the titanium source to the formate is (2-4):1, preferably (2.5-3.5):1;

[0061] Preferably, in step (2), the reaction temperature is 20 to 50°C, preferably 25 to 45°C;

[0062] Preferably, in step (2), the reaction time is 0.5 to 2 h, preferably 1 to 1.5 h.

[0063] After the titanium source and formate are mixed in a certain proportion and uniformly adsorbed, a L1-Ti(III)-OCHO-Ti(IV)-L1 structure can be formed, in which Ti(III) is coordinated with carbonyl oxygen and Ti(IV) is coordinated with carboxyl oxygen to form a double titanium structure monomer. Specifically, the titanium connected to the carbonyl oxygen is trivalent titanium, which is coordinated titanium, and the titanium negatively connected to oxygen is connected through transmetallation and becomes tetravalent titanium. Subsequent calcination is oxidized to tetravalent titanium.

[0064] Step (3) adding a silicon source and hydrothermally crystallizing the titanium to grow in a dual-core structure can be carried out as follows: adding a silicon source in a certain proportion to the solution of step (2), and hydrothermally crystallizing the resulting solution in a hydrothermal reactor at a certain temperature for a certain period of time;

[0065] Preferably, in step (3), the silicon source includes but is not limited to silicates, alkyl orthosilicates, alkyl metasilicates or combinations thereof. The alkyl orthosilicates include C1-C20 alkyl orthosilicates, preferably C1-C6 alkyl orthosilicates. In one example of the present application, the alkyl orthosilicates are selected from one or more of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate or butyl orthosilicate. In one example of the present application, the alkyl metasilicates include C1-C20 alkyl silicates, preferably C1-C6 alkyl silicates. In one example of the present application, the alkyl metasilicates are selected from one or more of methyl metasilicate, ethyl metasilicate, propyl metasilicate or butyl metasilicate. In one example of the present application, the silicate is selected from alkali metal silicates, preferably one or more of sodium silicate and potassium silicate;

[0066] In the present application, in the above step (3), the amount of the silicon source and the template agent is conventional, and the ordinary technicians in the field can reasonably determine the specific amount. Preferably, in step (3), the molar ratio of the silicon source to the template agent is (0.5-2):1, preferably (1-1.5):1;

[0067] Preferably, in step (3), the crystallization temperature is 100 to 240° C., preferably 200 to 220° C.;

[0068] Preferably, in step (3), the crystallization time is 4 to 16 hours, preferably 6 to 10 hours.

[0069] Step (4) washing and calcining to obtain a dual titanium core molecular sieve catalyst can be carried out, for example, as follows: the product obtained after crystallization is centrifuged, the obtained solid is washed with a solvent, and then calcined at a certain temperature for a certain time in an air atmosphere in a muffle furnace to obtain a dual titanium core molecular sieve catalyst.

[0070] Preferably, in step (4), the washing solvent is an organic solvent capable of dissolving the titanium source, preferably, the washing solvent is an aprotic solvent, preferably, the washing solvent is selected from one or more of tetrahydrofuran, dioxane, and toluene;

[0071] Preferably, in step (4), the calcination temperature is 400-600°C, preferably 450-550°C;

[0072] Preferably, in step (4), the calcination time is 10 to 72 hours, preferably 20 to 40 hours.

[0073] On the other hand, the present application provides a method for preparing a molecular sieve catalyst, the method comprising the following steps:

[0074] (1) mixing a template agent and a formate in a solvent to obtain a template solution;

[0075] (2) adding a titanium source so that formate adsorbs a pair of titanium cores to form a Ti(III)-Ti(IV) dual titanium core precursor;

[0076] (3) Adding silicon source and hydrothermal crystallization to grow titanium with a dual-core structure;

[0077] (4) washing and calcining to obtain a double titanium core molecular sieve catalyst.

[0078] The various details and preferred technical solutions in the method for preparing the molecular sieve catalyst are also described above.

[0079] In another aspect, the present application provides a method for preparing epichlorohydrin by epoxidizing allyl chloride, the method comprising reacting allyl chloride, hydrogen peroxide, a solvent and the molecular sieve catalyst according to the present disclosure.

[0080] Preferably, the molar ratio of the hydrogen peroxide to allyl chloride is 1:1-1:4.

[0081] Preferably, the reaction temperature is 15-40°C.

[0082] Preferably, the solvent is a protic solvent, for example an alcohol, such as methanol.

[0083] Preferably, the conversion rate of the hydrogen peroxide is greater than or equal to 98% (preferably greater than or equal to 98.5%), and the selectivity of epichlorohydrin is greater than or equal to 95% (preferably greater than or equal to 96%, more preferably greater than or equal to 97%, and even more preferably greater than or equal to 98%).

[0084] Preferably, the catalyst life is more than 1000 hours, preferably more than 1200 hours, more preferably more than 1500 hours, most preferably more than 1700 hours, and can reach up to 2500 hours, or 2300 hours, or 2100 hours, or 2000 hours.

[0085] In another aspect, the present application provides a use of the molecular sieve catalyst of the present application in catalyzing the epoxidation of 3-chloropropylene with hydrogen peroxide to produce epichlorohydrin.

[0086] Preferably, the conversion rate of the hydrogen peroxide is greater than or equal to 98% (preferably greater than or equal to 98.5%), and the selectivity of epichlorohydrin is greater than or equal to 95% (preferably greater than or equal to 96%, more preferably greater than or equal to 97%, and even more preferably greater than or equal to 98%).

[0087] Preferably, the catalyst life is more than 1000 hours, preferably more than 1200 hours, more preferably more than 1500 hours, most preferably more than 1700 hours, and can reach up to 2500 hours, or 2300 hours, or 2100 hours, or 2000 hours.

[0088] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0089] Example

[0090] Source of raw materials:

[0091] Methyl orthosilicate (Beijing Bailingwei Technology Co., Ltd.), Ethyl orthosilicate (Shanghai Aladdin Biochemical Technology Co., Ltd.), Sodium silicate (Sinopharm Chemical Reagent Co., Ltd.)

[0092] Tetrapropylammonium hydroxide (Beijing Bailingwei Technology Co., Ltd.), n-propylamine (Sinopharm Chemical Reagent Co., Ltd.), 2-chloroethanol (Merck Co., Ltd.), 2-bromoethanol (Merck Co., Ltd.)

[0093] Sodium formate (Sinopharm Chemical Reagent Co., Ltd.), Potassium formate (Shanghai Aladdin Biochemical Technology Co., Ltd.)

[0094] (2-Hydroxy-3,5-dimethyl)benzylamine (Qingdao Chemos Biochemical Technology Co., Ltd.), (2-Hydroxy-3,5-tert-butyl)benzylamine (Qingdao Chemos Biochemical Technology Co., Ltd.), (2-Hydroxy)benzylamine (Merck Co., Ltd.), trifluoromethanesulfonic acid (Shanghai Aladdin Biochemical Technology Co., Ltd.), titanium trichloride (Shanghai Aladdin Biochemical Technology Co., Ltd.)

[0095] Toluene (Sinopharm Chemical Reagent Co., Ltd.), tetrahydrofuran (Merck Co., Ltd.), dioxane (Sinopharm Chemical Reagent Co., Ltd.), deionized water (Suzhou Aying Water Treatment Co., Ltd.), isopropanol (Sinopharm Chemical Reagent Co., Ltd.), acetonitrile (Merck Co., Ltd.), methanol (Sinopharm Chemical Reagent Co., Ltd.)

[0096] n-Butylamine (Shanghai Aladdin Biochemical Technology Co., Ltd.)

[0097] Hydrogen peroxide (Jiangsu Ruiheng New Materials Co., Ltd.)

[0098] Titanium sulfate (Sinopharm Chemical Reagent Co., Ltd.)

[0099] Colloidal silica (Shanghai MacLean Biochemical Technology Co., Ltd.)

[0100] equipment:

[0101] Hydrothermal reactor (Beijing Century Senlang Experimental Instrument Co., Ltd., SLM100, SLM500); centrifuge (Hunan Xiangyi Laboratory Instrument Development Co., Ltd., H1850); muffle furnace (Pengda Kiln Factory, Luoyang High-tech Development Zone, Henan Province, model PD-MJ10); fixed bed reactor (Tianjin Aozhan Technology Co., Ltd., AZ-SE-1); autoclave (Shanghai Yanzheng Experimental Instrument Co., Ltd., YZQR-100, YZQR-500); GC (Agilent Technologies, USA, GC8890); ICP analyzer (Agilent Technologies, USA, ICPOES730)

[0102] Test method: Regular sampling for GC quantitative analysis, chemical titration of hydrogen peroxide content, calculation of hydrogen peroxide conversion rate, ECH selectivity, and alkenyl ether selectivity.

[0103] Determination of catalyst life: When the hydrogen peroxide conversion rate is lower than 92%, the catalyst is considered to be deactivated.

[0104] Calculation method for hydrogen peroxide conversion rate, epichlorohydrin (ECH) selectivity, and alkenyl ether selectivity: Hydrogen peroxide conversion rate is calculated by chemical titration of hydrogen peroxide residue in the reaction solution using the iodine titration method (GB / T 32102-2015). Epichlorohydrin selectivity and alkenyl ether selectivity are calculated by dividing the epichlorohydrin content and alkenyl ether content in the GC quantitative data by the hydrogen peroxide conversion rate.

[0105] Template synthesis method:

[0106] 1. Take 6.0g of n-propylamine and dissolve it in 50g of acetonitrile, add 25.2g of 2-chloroethanol, react at 65℃ for 12h, then dry the solvent and n-propylamine at 80℃, recrystallize the obtained solid with methanol / water, and filter to obtain tri(2-hydroxyethyl)propylammonium chloride.

[0107] 2. Take 5.9g of n-propylamine and dissolve it in 50g of acetonitrile, add 38.5g of 2-bromoethanol, react at 70℃ for 12h, then dry the solvent and n-propylamine at 80℃, recrystallize the obtained solid with methanol / water, and filter to obtain tri(2-hydroxyethyl)propylammonium bromide.

[0108] Complex synthesis method:

[0109] 1. Dissolve 7.2g (2-hydroxy-3,5-dimethyl) benzylamine in 40g toluene, add 0.51g trifluoromethanesulfonic acid in an ice bath, heat to 80°C and oxidize with oxygen for 15h, extract the reaction solution with water, desolventize the oil phase and recrystallize with methanol / water to obtain (2-hydroxy-3,5-dimethyl) benzaldehyde.

[0110] The above 8.4 g (2-hydroxy-3,5-dimethyl)benzaldehyde and 4.5 g (2-hydroxy-3,5-dimethyl)benzylamine were reacted in 50 g isopropanol at 60° C. for 2 h. The reaction solution was evaporated until solid was precipitated and then directly filtered to obtain tris(2-hydroxy-3,5-dimethyl)benzylamine ligand.

[0111] Under nitrogen atmosphere, 5.0 g of the above ligand and 2.4 g of titanium trichloride were stirred in 20 g of tetrahydrofuran at room temperature for 15 min, and then isopropanol was added dropwise until solid precipitated. The liquid was filtered to obtain tris(2-hydroxy-3,5-dimethyl)benzylamine titanium chloride.

[0112] 2. Dissolve 6.0 g (2-hydroxy) benzylamine in 40 g toluene, add 0.50 g trifluoromethanesulfonic acid in an ice bath, heat to 80 ° C and oxidize with oxygen for 15 hours, extract the reaction solution with water, desolventize the oil phase and recrystallize with methanol / water to obtain (2-hydroxy) benzaldehyde.

[0113] The above 7.1g (2-hydroxy)benzaldehyde and 3.6g (2-hydroxy)benzylamine were reacted in 50g isopropanol at 60°C for 2h, and the reaction solution was evaporated until solid precipitated and then directly filtered to obtain tri(2-hydroxy)benzylamine ligand

[0114] Under nitrogen atmosphere, 4.7 g of the above ligand and 2.3 g of titanium trichloride were stirred in 20 g of tetrahydrofuran at room temperature for 15 min, and then isopropanol was added dropwise until solid precipitated, and the liquid was filtered to obtain tri(2-hydroxy)benzylamine titanium chloride.

[0115] 3. Dissolve 9.8 g (2-hydroxy-3,5-tert-butyl) benzylamine in 40 g toluene, add 0.50 g trifluoromethanesulfonic acid in an ice bath, heat to 80 ° C and oxidize with oxygen for 15 hours, extract the reaction solution with water, desolventize the oil phase and recrystallize with methanol / water to obtain (2-hydroxy-3,5-tert-butyl) benzaldehyde.

[0116] The above 9.0 g (2-hydroxy-3,5-tert-butyl)benzaldehyde and 4.8 g (2-hydroxy-3,5-tert-butyl)benzylamine were reacted in 50 g isopropanol at 60° C. for 2 h. The reaction solution was evaporated until solid was precipitated and then directly filtered to obtain tri(2-hydroxy-3,5-tert-butyl)benzylamine ligand.

[0117] Under nitrogen atmosphere, 5.8 g of the above ligand and 2.4 g of titanium trichloride were stirred in 20 g of tetrahydrofuran at room temperature for 15 min, then isopropanol was added dropwise until solid precipitated, and the liquid was filtered to obtain tri(2-hydroxy-3,5-tert-butyl)benzylamine titanium chloride.

[0118] Examples 1 to 8 are examples of catalyst synthesis, and Comparative Example 1 is a TS-1 catalyst synthesized by a traditional method, which is used as a comparative example.

[0119] Example 1

[0120] (1) 22.7 g of tri(2-hydroxyethyl)propylammonium chloride and 0.27 g of sodium formate were added to 181 g of deionized water and reacted in a reaction bottle at 20° C. for 1 h to obtain a template solution;

[0121] (2) Dissolve 1.04 g of tris(2-hydroxy-3,5-dimethyl)benzylamine titanium chloride in 1.40 g of tetrahydrofuran, add to the template solution of step (1) after complete dissolution, and stir and adsorb at 25° C. for 1 h;

[0122] (3) Weigh 10.42 g of ethyl orthosilicate, add it to the solution of step (2), disperse it, put it into a hydrothermal reactor, and crystallize it at 220° C. for 10 h;

[0123] (4) The crystallized product was separated by centrifugation, and the obtained solid was washed with tetrahydrofuran and calcined in a muffle furnace at 450° C. in an air atmosphere for 40 h. The obtained catalyst was named C1.

[0124] The molar ratio of template, formate, water, titanium source, and silicon source is 1:0.04:100:0.02:0.5

[0125] Example 2

[0126] (1) 27.1 g of tris(2-hydroxyethyl)propylammonium bromide and 0.24 g of sodium formate were added to 39 g of deionized water and reacted in a reaction bottle at 20° C. for 4 h to obtain a template solution;

[0127] (2) dissolving 0.52 g of tris(2-hydroxy-3,5-dimethyl)benzylamine titanium chloride in 1.45 g of tetrahydrofuran, adding the mixture to the template solution of step (1) after it is completely dissolved, and stirring and adsorbing at 20° C. for 1 h;

[0128] (3) Weigh 7.73 g of methyl orthosilicate, add it to the solution of step (2), disperse it, put it into a hydrothermal reactor, and crystallize it at 120° C. for 12 h;

[0129] (4) The crystallized product was separated by centrifugation, and the obtained solid was washed with tetrahydrofuran and calcined in a muffle furnace at 400° C. in an air atmosphere for 20 h. The obtained catalyst was called C2.

[0130] The molar ratio of template, formate, water, titanium source, and silicon source is 1:0.035:20:0.01:0.5

[0131] Example 3

[0132] (1) 22.6 g of tri(2-hydroxyethyl)propylammonium chloride and 0.25 g of potassium formate were added to 357 g of deionized water and reacted in a reaction bottle at 10° C. for 8 h to obtain a template solution;

[0133] (2) dissolving 0.42 g of tri(2-hydroxy)benzylamine titanium chloride in 1.44 g of tetrahydrofuran, adding the mixture to the template solution of step (1) after it is completely dissolved, and stirring and adsorbing at 30° C. for 1 h;

[0134] (3) Weigh 21.10 g of tetraethyl orthosilicate, add it to the solution of step (2), disperse it, put it into a hydrothermal reactor, and crystallize it at 220° C. for 6 h;

[0135] (4) The crystallized product was separated by centrifugation, and the obtained solid was washed with tetrahydrofuran and calcined in a muffle furnace at 550° C. in an air atmosphere for 10 h. The obtained catalyst was called C3.

[0136] The molar ratio of template, formate, water, titanium source, and silicon source is 1:0.03:200:0.01:1

[0137] Example 4

[0138] (1) 22.8 g of tri(2-hydroxyethyl)propylammonium chloride and 0.38 g of potassium formate were added to 184 g of deionized water and reacted in a reaction bottle at 35° C. for 0.5 h to obtain a template solution;

[0139] (2) Dissolve 1.71 g of tri(2-hydroxy-3,5-tert-butyl)benzylamine titanium chloride in 2.00 g of toluene, add it to the template solution of step (1) after it is completely dissolved, and stir and adsorb at 50° C. for 0.5 h;

[0140] (3) Weigh 56.81 g of sodium silicate, add it to the solution of step (2), disperse it, put it into a hydrothermal reactor, and crystallize it at 240° C. for 4 h;

[0141] (4) The crystallized product was separated by centrifugation, and the obtained solid was washed with toluene and calcined in a muffle furnace at 500° C. in an air atmosphere for 48 h. The obtained catalyst was called C4.

[0142] The molar ratio of template, formate, water, titanium source, and silicon source is 1:0.045:100:0.0225:2

[0143] Example 5

[0144] (1) 27.5 g of tris(2-hydroxyethyl)propylammonium bromide and 0.27 g of sodium formate were added to 898 g of deionized water and reacted in a reaction bottle at 40° C. for 12 h to obtain a template solution;

[0145] (2) dissolving 0.51 g of tris(2-hydroxy-3,5-dimethyl)benzylamine titanium chloride in 1.44 g of toluene, adding the mixture to the template solution of step (1) after it is completely dissolved, and adsorbing the mixture at 45° C. with stirring for 2 h;

[0146] (3) Weigh 31.25 g of ethyl orthosilicate, add it to the solution in step (2), disperse it, put it into a hydrothermal reactor, and crystallize it at 200° C. for 10 h;

[0147] (4) The crystallized product was separated by centrifugation, and the obtained solid was washed with toluene and calcined in a muffle furnace at 450° C. in an air atmosphere for 72 h. The obtained catalyst was named C5.

[0148] The molar ratio of template, formate, water, titanium source, and silicon source is 1:0.04:500:0.01:1.5

[0149] Example 6

[0150] (1) 22.8 g of tri(2-hydroxyethyl)propylammonium chloride and 0.21 g of sodium formate were added to 265 g of deionized water and reacted in a reaction bottle at 20° C. for 2 h to obtain a template solution;

[0151] (2) Dissolve 0.91 g of tri(2-hydroxy-3,5-tert-butyl)benzylamine titanium chloride in 1.12 g of dioxane, add to the template solution of step (1) after complete dissolution, and stir and adsorb at 20° C. for 1 h;

[0152] (3) Weigh 14.23 g of sodium silicate, add it to the solution in step (2), disperse it, put it into a hydrothermal reactor, and crystallize it at 100° C. for 16 h;

[0153] (4) The crystallized product was separated by centrifugation, and the obtained solid was washed with dioxane and calcined in a muffle furnace at 600° C. in an air atmosphere for 12 h. The obtained catalyst was called C6.

[0154] The molar ratio of template, formate, water, titanium source, and silicon source is 1:0.03:150:0.012:0.5

[0155] Example 7

[0156] (1) 27.4 g of tris(2-hydroxyethyl)propylammonium bromide and 0.20 g of sodium formate were added to 177 g of deionized water and reacted in a reaction bottle at 45° C. for 6 h to obtain a template solution;

[0157] (2) dissolving 0.76 g of tris(2-hydroxy-3,5-dimethyl)benzylamine titanium chloride in 0.77 g of tetrahydrofuran, adding the mixture to the template solution of step (1) after it is completely dissolved, and adsorbing the mixture at 45° C. with stirring for 1.5 h;

[0158] (3) Weigh 20.83 g of tetraethyl orthosilicate, add it to the solution of step (2), disperse it, put it into a hydrothermal reactor, and crystallize it at 240° C. for 8 h;

[0159] (4) The crystallized product was separated by centrifugation, and the obtained solid was washed with tetrahydrofuran and calcined in a muffle furnace at 450° C. in an air atmosphere for 24 h. The obtained catalyst was named C7.

[0160] The molar ratio of template, formate, water, titanium source, and silicon source is 1:0.03:100:0.015:1

[0161] Example 8

[0162] (1) 22.6 g of tri(2-hydroxyethyl)propylammonium chloride and 0.29 g of potassium formate were added to 364 g of deionized water and reacted in a reaction bottle at 20° C. for 4 h to obtain a template solution;

[0163] (2) Dissolve 0.71 g of tris(2-hydroxy-3,5-dimethyl)benzylamine titanium chloride in 2.44 g of dioxane, add to the template solution of step (1) after complete dissolution, and stir and adsorb at 30° C. for 2 h;

[0164] (3) Weigh 10.65 g of methyl orthosilicate, add it to the solution of step (2), disperse it, put it into a hydrothermal reactor, and crystallize it at 220° C. for 10 h;

[0165] (4) The crystallized product was separated by centrifugation, and the obtained solid was washed with dioxane and calcined in a muffle furnace at 400° C. in an air atmosphere for 42 h. The obtained catalyst was named C8.

[0166] The molar ratio of template, formate, water, titanium source, and silicon source is 1:0.035:200:0.014:0.7

[0167] Comparative Example 1

[0168] In a 2L four-necked bottle, add 61g of tetrapropylammonium hydroxide, 585g of n-butylamine, 600g of colloidal silica and 400mL of deionized water, then mix 166mL of 30% hydrogen peroxide, 79g of titanium sulfate and 59g of isopropanol, and drop into the silica sol. After ultrasonic stirring, add it into an autoclave and crystallize it at 200℃ for 48h. After crystallization, wash, centrifuge, dry, and finally calcine at 550℃ for 5h to obtain TS-1 molecular sieve catalyst.

[0169] Catalyst Inductively Coupled Plasma Optical Emission Spectroscopy (ICP) Analysis:

[0170]

[0171]

[0172] Catalyst molding:

[0173] The catalysts in all the above examples are further subjected to a forming step in order to be loaded into a fixed bed reactor:

[0174] The catalyst synthesized in the above example was mixed with 50 wt% silica sol and 20 wt% hydroxymethyl cellulose and then extruded using a twin-screw extruder to obtain a catalyst that can be evaluated.

[0175] Catalyst Evaluation:

[0176] The above-formed catalyst was evaluated using a fixed bed reactor. The fixed bed had a length of 180 cm and an inner diameter of 0.8 cm and was loaded with 35 g of the above catalyst. The molar ratio of the raw materials of the chloropropylene reaction liquid was: chloropropylene: 50% hydrogen peroxide: methanol = 1:3:8; the reaction temperature was 20-25°C, and samples were taken every 2 hours for testing. The specific reaction space velocity, hydrogen peroxide conversion rate, ECH selectivity, alkenyl ether selectivity, and catalyst life (a hydrogen peroxide conversion rate lower than 92% is considered deactivated) are shown in the following table:

[0177] Evaluation example Catalyst No. Hydrogen peroxide conversion rate / % ECH selectivity / % Alkenyl ether selectivity / % <![CDATA[Reaction space velocity / h -1 > Catalyst life / h 1 C1 99.8 98.1 0.4 12 2048 2 C2 99.1 98.2 0.3 6 1788 3 C3 98.9 98.7 0.3 7 2455 4 C4 99.4 97.0 0.7 8.5 1439 5 C5 99.1 96.7 0.6 7 1250 6 C6 98.7 97.4 0.4 10 2004 7 C7 98.8 97.6 0.8 5 1987 8 C8 99.0 98.4 0.7 7 1658 9 TS-1 99.6 96.8 1.8 2 1246

[0178] From the above examples, it can be seen that compared with the traditional TS-1 catalyst, the double titanium site catalyst can accommodate a higher reaction space velocity while having a higher hydrogen peroxide conversion rate and epichlorohydrin selectivity, and at the same time, the by-product vinyl ether content is lower.

[0179] The above description is only a preferred embodiment of the present disclosure and is not intended to limit the scope of the substantial technical content of the present disclosure. The substantial technical content of the present disclosure is broadly defined in the scope of the claims of the application. Any technical entity or method completed by others, if it is exactly the same as that defined in the scope of the claims of the application or an equivalent variation, will be deemed to be included in the scope of the claims.

[0180] All documents mentioned in this disclosure are cited as references in this application, just as each document is cited as reference individually. In addition, it should be understood that after reading the above content of this disclosure, those skilled in the art may make various changes or modifications to this disclosure, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A molecular sieve catalyst, the catalyst being prepared by a method comprising the following steps: (1) mixing a template agent and a formate in a solvent to obtain a template solution; (2) adding a titanium source so that formate adsorbs a pair of titanium cores to form a Ti(III)-Ti(IV) dual titanium core precursor; (3) Adding silicon source and hydrothermal crystallization to grow titanium with a dual-core structure; (4) washing and calcining to obtain a double titanium core molecular sieve catalyst.

2. The molecular sieve catalyst as claimed in claim 1, wherein in step (1), the template is selected from one or more organic amines substituted with one or more hydroxyl groups, quaternary ammonium salts substituted with one or more hydroxyl groups or amino groups, preferably, the template is selected from one or more C1-C6 organic amines substituted with one or more hydroxyl groups, tetraalkylammonium halide salts substituted with one or more hydroxyl groups or amino groups; more preferably, the template is selected from tris(hydroxy C1-6 alkyl)C1-6 alkylammonium halides, tris(amino C1-6 alkyl)C1-6 One or more of alkyl ammonium halides, di(hydroxy C1-6 alkyl)diC1-6 alkyl ammonium halides, di(amino C1-6 alkyl)diC1-6 alkyl ammonium halides, (hydroxy C1-6 alkyl)triC1-6 alkyl ammonium halides, (amino C1-6 alkyl)triC1-6 alkyl ammonium halides, ethanolamine, diethanolamine, diglycolamine, diisopropanolamine, methyldiethanolamine, triethanolamine, more preferably, the template is selected from one or more of tri(2-hydroxyethyl)propylammonium chloride and tri(2-hydroxyethyl)propylammonium bromide; and / or In step (1), the formate is selected from one or more of alkali metal formates, alkaline earth metal formates, formates of IIIA metals, and ammonium formate. Preferably, the formate is selected from one or more of sodium formate, potassium formate, magnesium formate, calcium formate, aluminum formate, and ammonium formate, or the formate is selected from one or more of sodium formate and potassium formate; and / or In step (1), the solvent is water; and / or In step (1), the molar ratio of the template to the formate is 1:(0.03-0.45), preferably 1:(0.035-0.4); and / or In step (1), the mixing temperature is 10-45°C or 20-40°C.

3. The molecular sieve catalyst according to claim 1, wherein in step (2), the titanium source is L1-TiHal, wherein Hal is a halogen, preferably L1-TiCl, wherein the ligand L1 is the following structure: Wherein the substituent R1 is hydrogen or C 1-6 Alkyl, preferably H, methyl or tert-butyl, more preferably methyl; wherein the substituent R2 is hydrogen or C 1-6 Alkyl, preferably H, methyl or tert-butyl, more preferably methyl; and / or In step (2), the solvent used is an aprotic solvent, preferably, one or more selected from tetrahydrofuran, dioxane, toluene; and / or In step (2), the molar ratio of the titanium source to the formate is (2-4):1, preferably (2.5-3.5):1; and / or In step (2), the reaction temperature is 20 to 50°C, preferably 25 to 45°C.

4. The molecular sieve catalyst according to claim 1, wherein in step (3), the silicon source is selected from one or more of silicates, alkyl orthosilicates, and alkyl metasilicates; preferably, the alkyl orthosilicate is selected from C1-C20 alkyl orthosilicates, the alkyl metasilicate is selected from C1-C20 alkyl silicates, and the silicate is selected from alkali metal silicates; more preferably, the alkyl orthosilicate is selected from one or more of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, or butyl orthosilicate, the alkyl metasilicate is selected from one or more of methyl metasilicate, ethyl metasilicate, propyl metasilicate, or butyl metasilicate, and the silicate is selected from one or more of sodium silicate and potassium silicate; and / or In step (3), the molar ratio of the silicon source to the template is (0.5-2):1, preferably (1-1.5):1; and / or In step (3), the crystallization temperature is 100 to 240° C., preferably 200 to 220° C.; and / or In step (3), the crystallization time is 4 to 16 hours, preferably 6 to 10 hours.

5. The molecular sieve catalyst according to claim 1, wherein in step (4), the solvent used for washing is an aprotic solvent, preferably one or more selected from tetrahydrofuran, dioxane, and toluene; and / or In step (4), the calcination temperature is 400-600°C, preferably 450-550°C; and / or In step (4), the calcination time is 10 to 72 hours, preferably 20 to 40 hours.

6. A method for preparing a molecular sieve catalyst, the method comprising the following steps: (1) mixing a template agent and a formate in a solvent to obtain a template solution; (2) adding a titanium source so that formate adsorbs a pair of titanium cores to form a Ti(III)-Ti(IV) dual titanium core precursor; (3) Adding silicon source and hydrothermal crystallization to grow titanium with a dual-core structure; (4) washing and calcining to obtain a double titanium core molecular sieve catalyst.

7. The method of claim 6, wherein in step (1), the template is selected from one or more organic amines substituted with one or more hydroxyl groups, quaternary ammonium salts substituted with one or more hydroxyl groups or amino groups, preferably, the template is selected from one or more C1-C6 organic amines substituted with one or more hydroxyl groups, tetraalkylammonium halides substituted with one or more hydroxyl groups or amino groups; more preferably, the template is selected from tris(hydroxy C1-6 alkyl)C1-6 alkylammonium halides, tris(amino C1-6 alkyl)C1-6 alkylammonium halides, One or more of ammonium halide, di(hydroxy C1-6 alkyl)diC1-6 alkylammonium halide, di(amino C1-6 alkyl)diC1-6 alkylammonium halide, (hydroxy C1-6 alkyl)triC1-6 alkylammonium halide, (amino C1-6 alkyl)triC1-6 alkylammonium halide, ethanolamine, diethanolamine, diglycolamine, diisopropanolamine, methyldiethanolamine, triethanolamine, more preferably, the template is selected from one or more of tri(2-hydroxyethyl)propylammonium chloride and tri(2-hydroxyethyl)propylammonium bromide; and / or In step (1), the formate is selected from one or more of alkali metal formates, alkaline earth metal formates, formates of IIIA metals, and ammonium formate. Preferably, the formate is selected from one or more of sodium formate, potassium formate, magnesium formate, calcium formate, aluminum formate, and ammonium formate, or the formate is selected from one or more of sodium formate and potassium formate; and / or In step (1), the solvent is water; and / or In step (1), the molar ratio of the template, the formate and the solvent is 1:(0.03-0.45):(20-500), preferably 1:(0.035-0.4):(100-200); and / or In step (1), the mixing temperature is 10 to 45° C. or 20 to 40° C.; and / or In step (2), the titanium source is L1-TiHal, wherein Hal is a halogen, preferably L1-TiCl, wherein the ligand L1 is the following structure: Wherein the substituent R1 is hydrogen or C 1-6 Alkyl, preferably H, methyl or tert-butyl, more preferably methyl; wherein the substituent R2 is hydrogen or C 1-6 Alkyl, preferably H, methyl or tert-butyl, more preferably methyl; and / or In step (2), the solvent used is an aprotic solvent, preferably, one or more selected from tetrahydrofuran, dioxane, toluene; and / or In step (2), the molar ratio of the titanium source to the formate is (2-4):1, preferably (2.5-3.5):1; and / or In step (2), the reaction temperature is 20 to 50°C, preferably 25 to 45°C.

8. The method according to claim 6, wherein in step (3), the silicon source is selected from one or more of silicates, alkyl orthosilicates, and alkyl metasilicates; preferably, the alkyl orthosilicate is selected from C1-C20 alkyl orthosilicates, the alkyl metasilicate is selected from C1-C20 alkyl silicates, and the silicate is selected from alkali metal silicates; more preferably, the alkyl orthosilicate is selected from one or more of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, or butyl orthosilicate, the alkyl metasilicate is selected from one or more of methyl metasilicate, ethyl metasilicate, propyl metasilicate, or butyl metasilicate, and the silicate is selected from one or more of sodium silicate and potassium silicate; and / or In step (3), the molar ratio of the silicon source to the template is (0.5-2):1, preferably (1-1.5):1; and / or In step (3), the crystallization temperature is 100 to 240° C., preferably 200 to 220° C.; and / or In step (3), the crystallization time is 4 to 16 hours, preferably 6 to 10 hours; and / or In step (4), the solvent used for washing is an aprotic solvent, preferably, the solvent used for washing is selected from one or more of tetrahydrofuran, dioxane, toluene; and / or In step (4), the calcination temperature is 400-600°C, preferably 450-550°C; and / or In step (4), the calcination time is 10 to 72 hours, preferably 20 to 40 hours.

9. A method for preparing epichlorohydrin by epoxidizing allyl chloride, the method comprising reacting allyl chloride, hydrogen peroxide, a solvent and the molecular sieve catalyst according to claims 1-5.

10. Use of the molecular sieve catalyst as claimed in claims 1 to 5 in catalyzing the epoxidation of 3-chloropropylene with hydrogen peroxide to produce epichlorohydrin.

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