Titanium-silicon molecular sieve, preparation method thereof and method for producing epoxy compound by oxidation reaction of macromolecular olefin
阅读说明：本技术 钛硅分子筛及其制备方法和大分子烯烃氧化反应生产环氧化合物的方法 (Titanium-silicon molecular sieve, preparation method thereof and method for producing epoxy compound by oxidation reaction of macromolecular olefin ) 是由 夏长久 杨永佳 朱斌 林民 彭欣欣 忻睦迪 史延强 罗一斌 舒兴田 于 2019-10-31 设计创作，主要内容包括：本公开涉及一种钛硅分子筛及其制备方法和大分子烯烃氧化反应生产环氧化合物的方法,钛硅分子筛由氧元素、硅元素和钛元素组成,以氧化物计并以摩尔量计,钛硅分子筛的TiO-2与SiO-2的摩尔比为1：(20-100)；钛硅分子筛的表面钛硅比与体相钛硅比的比值为1.6-3.9,钛硅比是指TiO-2与SiO-2的摩尔比；钛硅分子筛的介孔最可几孔径为15-35nm。本公开的钛硅分子筛表面富钛且具有适宜的介孔最可几孔径,将其用于大分子烯烃氧化生产环氧化合物的工艺中可以提高原料转化率和目标产物选择性。(The present disclosure relates to a titanium silicalite molecular sieve and a preparation method thereof, and a method for producing an epoxy compound by a macromolecule olefin oxidation reaction, wherein the titanium silicalite molecular sieve is composed of an oxygen element, a silicon element and a titanium element, and TiO of the titanium silicalite molecular sieve is calculated by oxides and calculated by mol 2 With SiO 2 In a molar ratio of 1: (20-100); the ratio of the surface titanium-silicon ratio of the titanium-silicon molecular sieve to the bulk phase titanium-silicon ratio is 1.6-3.9, and the titanium-silicon ratio refers to TiO 2 With SiO 2 The molar ratio of (A) to (B); the most probable pore diameter of the titanium-silicon molecular sieve is 15-35 nm. The titanium silicalite molecular sieve disclosed by the invention is rich in titanium on the surface and has proper mesopore and most probable pore diameter, and is used for producing rings by oxidizing macromolecular olefinsThe oxygen compound process can improve the conversion rate of raw materials and the selectivity of target products.)
1. The titanium silicalite molecular sieve is characterized by consisting of oxygen element, silicon element and titanium element, wherein TiO of the titanium silicalite molecular sieve is calculated by oxide and calculated by molar weight2With SiO2In a molar ratio of 1: (20-100); the ratio of the surface titanium-silicon ratio of the titanium-silicon molecular sieve to the bulk phase titanium-silicon ratio is 1.6-3.9, wherein the titanium-silicon ratio refers to TiO2With SiO2The molar ratio of (A) to (B); the most probable pore diameter of the titanium-silicon molecular sieve is 15-35 nm.
2. The titanium silicalite molecular sieve of claim 1, wherein the titanium silicalite molecular sieve has a mesopore to mesopore diameter of 18-30 nm.
3. The titanium silicalite molecular sieve of claim 1, wherein the titanium silicalite molecular sieve has a BET total specific surface area of 420-650m2The volume ratio of the mesoporous volume to the total pore volume is 40-70%.
4. The titanium silicalite molecular sieve of any one of claims 1 to 3, wherein the titanium silicalite molecular sieve has an intragranular multiple hollow structure.
5. A method of preparing a titanium silicalite molecular sieve, the method comprising:
a. mixing a first structure directing agent, a first silicon source, a first titanium source and water, and then carrying out first hydrolysis for 2-50 hours at 40-97 ℃ to obtain a first hydrolysis mixture;
b. carrying out first hydrothermal treatment on the first hydrolysis mixture in a pressure-resistant closed container at 90-200 ℃ for 1-700 hours, and collecting a first solid product;
c. mixing a second structure directing agent, a second silicon source, a second titanium source and water, and performing second hydrolysis at 35-95 ℃ for 3-60 hours to obtain a second hydrolysis mixture;
d. mixing the first solid product, the second hydrolysis mixture and an optional inorganic ammonium source to obtain a mixed material, carrying out second hydrothermal treatment on the mixed material in a pressure-resistant closed container at 90-200 ℃ for 1-160 hours, and collecting a second solid product;
wherein the first structure directing agent is a double-head organic quaternary ammonium salt compound, or a mixture of the double-head organic quaternary ammonium salt compound and organic amine; the second structure directing agent is a single-head quaternary ammonium base compound or a mixture of the single-head quaternary ammonium base compound and organic amine;
the molar ratio of the first titanium source to the first silicon source is smaller than that of the second titanium source to the second silicon source, and the first silicon source and the second silicon source are made of SiO2Meter, the first titanium source andthe second titanium source is TiO2And (6) counting.
6. The method of claim 5, wherein in step a, the double-headed organic quaternary ammonium base compound and the double-headed organic quaternary ammonium salt compound each have the following structure:
wherein R is1Is C3-C30 chain normal alkyl, R2Is a chain normal alkylene of C1-C10, R3Is C1-C15 chain normal alkyl, R4、R5、R6And R7Each independently being methyl, ethyl or propyl, X is OH-、F-、Cl-Or Br-。
7. The method of claim 6, wherein R1Is C9-C23 chain normal alkyl, R2Is a chain normal alkylene of C6-C8, R3Is C1-C7 chain normal alkyl, R4、R5、R6And R7Each independently being methyl or ethyl, X is OH-Or Br-。
8. The method as claimed in claim 5, wherein, in step c, the single-headed quaternary ammonium base compound has the formula (R)9)3NOH，R9Is C1-C4 alkyl;
the molecular formula of the single-head quaternary ammonium salt compound is (R)10)3NX，R10Is C1-C4 alkyl, X is F-、Cl-Or Br-。
9. The method of claim 5, wherein the organic amine is an aliphatic amine compound, an alcohol amine compound, or an aromatic amine compound, or a combination of two or three thereof.
10. The method of claim 9, wherein the fatty amine compound is ethylamine, n-butylamine, butanediamine, or hexanediamine, or a combination of two or three thereof;
the alcohol amine compound is monoethanolamine, diethanolamine or triethanolamine, or a combination of two or three of the monoethanolamine, diethanolamine and triethanolamine;
the aromatic amine compound is aniline, toluidine or p-phenylenediamine, or a combination of two or three of them.
11. The method of claim 5, wherein in step a, the molar ratio of the amounts of the first structure directing agent, the first silicon source, the first titanium source and water is (0.01-1): 1: (0.001-0.05): (50-4000), wherein the first silicon source is SiO2The first titanium source is calculated as TiO2Counting;
preferably, the molar ratio of the amounts of the first structure directing agent, the first silicon source, the first titanium source and water is (0.06-0.5): 1: (0.005-0.02): (200-2000).
12. The method of claim 5, wherein the first and second silicon sources are each an organosilicate, preferably each independently is tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate, or dimethoxydiethoxysilane, or a combination of two or three thereof;
the first titanium source and the second titanium source are each independently an inorganic titanium salt and/or an organic titanate.
13. The process of claim 5, wherein in step a, the temperature of the first hydrolysis is 65-95 ℃ for 3-35 hours; and/or the like and/or,
in the step b, the temperature of the first hydrothermal treatment is 120-180 ℃, and the time is 5-550 hours.
14. The method of claim 5, whereinIn step c, the molar ratio of the second structure directing agent, the second silicon source, the second titanium source and the water is (1.5-5): (10-100): 1: (400-1000), the second silicon source is SiO2The second titanium source is calculated as TiO2And (6) counting.
15. The process according to claim 5, wherein in step c, the temperature of the second hydrolysis is 50-90 ℃ for 5-40 hours.
16. The method of claim 5, wherein in step d, the inorganic ammonium source is ammonium chloride, ammonium sulfate, ammonium oxalate, ammonium carbonate, or aqueous ammonia, or a combination of two or three thereof.
17. The method as claimed in claim 5, wherein the temperature of the second hydrothermal treatment in step d is 185 ℃ for 5-165 hours.
18. The method of claim 5, wherein the TiO in the mixed material2、SiO2And NH4 +In a molar ratio of 1: (10-200): (0-4), preferably, TiO2、SiO2And NH4 +In a molar ratio of 1: (20-100): (0.1-0.8).
19. The method of claim 5, wherein step d further comprises: collecting the second solid product, and then drying and roasting; the drying temperature is 100-200 ℃, and the drying time is 1-24 hours; the roasting temperature is 350-650 ℃, and the roasting time is 1-6 hours.
20. A titanium silicalite molecular sieve produced by the process of any one of claims 5 to 19.
21. A catalyst comprising the titanium silicalite molecular sieve of any one of claims 1 to 4 and claim 20.
22. A process for the oxidation of a large olefin to produce an epoxy compound, which process uses the catalyst of claim 21.
23. A process according to claim 23, wherein the macromolecular alkene is cyclohexene, cyclooctene, styrene or limonene.
Technical Field
The disclosure relates to a titanium silicalite molecular sieve, a preparation method thereof and a method for producing an epoxy compound by oxidation reaction of macromolecular olefin.
Background
The titanium-silicon molecular sieve is a novel heteroatom molecular sieve developed in the beginning of the eighties of the 20 th century and refers to a class of heteroatom molecular sieves containing framework titanium. The microporous titanium silicalite molecular sieves synthesized at present comprise TS-1(MFI structure), TS-2(MEL structure), Ti-Beta (BEA structure), Ti-ZSM-12(MTW structure), Ti-MCM-22(MWW structure) and the like, and the mesoporous titanium silicalite molecular sieves comprise Ti-MCM-41, Ti-SBA-15 and the like. The development and application of the titanium-silicon molecular sieve successfully expand the zeolite molecular sieve from the acid catalysis field to the catalytic oxidation field, and have milestone significance. Of these, Enichem, Italy, first published TS-1 in 1983 as the most representative titanium silicalite molecular sieve. TS-1 has MFI topology with a two-dimensional ten-membered ring channel system, which [100 ]]The direction is a straight channel with a pore diameter of 0.51X 0.55nm, [010]The direction is sinusoidal channels with pore diameter of 0.53 x 0.56 nm. Due to the introduction of Ti atoms and the special pore channel structure, TS-1 and H2O2The formed oxidation system has the advantages of mild reaction conditions, green and environment-friendly oxidation process and good selectivity of oxidation products in the oxidation reaction of organic mattersAnd the like. At present, the catalytic oxidation system can be widely applied to reactions such as alkane oxidation, olefin epoxidation, phenol hydroxylation, ketone (aldehyde) ammoximation, oil oxidation desulfurization and the like, wherein industrial application is successively realized in phenol hydroxylation, ketone (cyclohexanone, butanone and acetone) ammoximation and propylene epoxidation.
The US patent 4410501 first discloses a method for synthesizing a titanium silicalite TS-1 by a classical hydrothermal crystallization method. The method is mainly carried out by two steps of glue preparation and crystallization, and comprises the following specific steps: putting silicon source Tetraethoxysilane (TEOS) into nitrogen to protect CO2Slowly adding template tetrapropylammonium hydroxide (TPAOH), slowly dropwise adding titanium source tetraethyl titanate (TEOT), stirring for 1h to prepare a reaction mixture containing silicon, titanium and organic alkali, heating, removing alcohol, replenishing water, crystallizing for 10 days at 175 ℃ under the stirring of an autogenous pressure kettle, separating, washing, drying and roasting to obtain the TS-1 molecular sieve. However, in the process, factors influencing insertion of titanium into the framework are numerous, conditions of hydrolysis, crystallization nucleation and crystal growth are not easy to control, a certain amount of titanium cannot be effectively inserted into the molecular sieve framework and is retained in a pore channel in a non-framework titanium form, the generation of non-framework titanium not only reduces the number of catalytic active centers, but also promotes ineffective decomposition of hydrogen peroxide by non-framework titanium silicon species to cause raw material waste, so that the TS-1 molecular sieve synthesized by the method has the defects of low catalytic activity, poor stability, difficulty in reproduction and the like.
In the preparation method of titanium silicalite TS-1(Zeolite, 1992, Vol.12, pages 943-950) disclosed by Thangaraj et al, in order to effectively improve the insertion of titanium into a molecular sieve framework, a strategy of hydrolyzing organic silicone grease firstly and then slowly dripping organic titanate for hydrolysis is adopted, the hydrolysis speed of organic silicon and titanium is matched, and isopropanol is introduced in the hydrolysis process of titanium, however, the titanium silicalite TS-1 obtained by the method is limited in the aspect of improving the content of framework titanium, a certain amount of non-framework titanium such as anatase still exists, and the catalytic activity is not high.
CN1301599A discloses a method for preparing a novel hollow titanium silicalite molecular sieve HTS with a hollow structure and less non-framework titanium, which comprises the steps of uniformly mixing a synthesized TS-1 molecular sieve, an acidic compound and water, reacting for 5 minutes to 6 hours at 5 to 95 ℃ to obtain an acid-treated TS-1 molecular sieve, uniformly mixing the acid-treated TS-1 molecular sieve, an organic base and the water, putting the obtained mixture into a sealed reaction kettle, and reacting for 1 hour to 8 days at the temperature of 120 to 200 ℃ and the autogenous pressure. The molecular sieve has less non-framework titanium and better catalytic oxidation activity and stability.
Disclosure of Invention
The titanium silicalite molecular sieve disclosed by the invention is rich in titanium on the surface and has proper mesopore and most probable pore diameter, and the conversion rate of raw materials and the selectivity of a target product can be improved when the titanium silicalite molecular sieve is used in a process for producing an epoxy compound by oxidizing macromolecular olefin.
In order to achieve the above objects, the present disclosure provides a titanium silicalite molecular sieve, which is composed of an oxygen element, a silicon element and a titanium element, and the titanium silicalite molecular sieve is TiO in terms of oxides and molar weight2With SiO2In a molar ratio of 1: (20-100); the ratio of the surface titanium-silicon ratio of the titanium-silicon molecular sieve to the bulk phase titanium-silicon ratio is 1.6-3.9, wherein the titanium-silicon ratio refers to TiO2With SiO2The molar ratio of (A) to (B); the most probable pore diameter of the titanium-silicon molecular sieve is 15-35 nm.
Optionally, the mesoporous and several-pore diameter of the titanium silicalite molecular sieve is 18-30 nm.
Optionally, the titanium silicalite molecular sieve has a BET total specific surface area of 420-650m2The volume ratio of the mesoporous volume to the total pore volume is 40-70%.
Optionally, the titanium silicalite molecular sieve has an intragranular multiple hollow structure.
A second aspect of the present disclosure provides a method of preparing a titanium silicalite molecular sieve, the method comprising:
a. mixing a first structure directing agent, a first silicon source, a first titanium source and water, and then carrying out first hydrolysis for 2-50 hours at 40-97 ℃ to obtain a first hydrolysis mixture;
b. carrying out first hydrothermal treatment on the first hydrolysis mixture in a pressure-resistant closed container at 90-200 ℃ for 1-700 hours, and collecting a first solid product;
c. mixing a second structure directing agent, a second silicon source, a second titanium source and water, and performing second hydrolysis at 35-95 ℃ for 3-60 hours to obtain a second hydrolysis mixture;
d. mixing the first solid product, the second hydrolysis mixture and an optional inorganic ammonium source to obtain a mixed material, carrying out second hydrothermal treatment on the mixed material in a pressure-resistant closed container at 90-200 ℃ for 1-160 hours, and collecting a second solid product;
wherein the first structure directing agent is a double-head organic quaternary ammonium salt compound, or a mixture of the double-head organic quaternary ammonium salt compound and organic amine; the second structure directing agent is a single-head quaternary ammonium base compound or a mixture of the single-head quaternary ammonium base compound and organic amine;
the molar ratio of the first titanium source to the first silicon source is smaller than that of the second titanium source to the second silicon source, and the first silicon source and the second silicon source are made of SiO2The first titanium source and the second titanium source are calculated as TiO2And (6) counting.
Optionally, in step a, the double-headed organic quaternary ammonium base compound and the double-headed organic quaternary ammonium salt compound have the following structures, respectively:
wherein R is1Is C3-C30 chain normal alkyl, R2Is a chain normal alkylene of C1-C10, R3Is C1-C15 chain normal alkyl, R4、R5、R6And R7Each independently being methyl, ethyl or propyl, X is OH-、F-、Cl-Or Br-。
Alternatively, R1Is C9-C23 chain normal alkyl, R2Is a chain normal alkylene of C6-C8, R3Is C1-C7 chain normal alkyl, R4、R5、R6And R7Each independently of the others being methyl orEthyl radical, X is OH-Or Br-。
Optionally, in step c, the single-headed quaternary ammonium base compound has the formula (R)9)3NOH，R9Is C1-C4 alkyl;
the molecular formula of the single-head quaternary ammonium salt compound is (R)10)3NX，R10Is C1-C4 alkyl, X is F-、Cl-Or Br-。
Optionally, the organic amine is an aliphatic amine compound, an alcohol amine compound, or an aromatic amine compound, or a combination of two or three thereof.
Optionally, the fatty amine compound is ethylamine, n-butylamine, butanediamine, or hexamethylenediamine, or a combination of two or three thereof;
the alcohol amine compound is monoethanolamine, diethanolamine or triethanolamine, or a combination of two or three of the monoethanolamine, diethanolamine and triethanolamine;
the aromatic amine compound is aniline, toluidine or p-phenylenediamine, or a combination of two or three of them.
Optionally, in step a, the molar ratio of the first structure directing agent, the first silicon source, the first titanium source and the water is (0.01-1): 1: (0.001-0.05): (50-4000), wherein the first silicon source is SiO2The first titanium source is calculated as TiO2Counting;
preferably, the molar ratio of the amounts of the first structure directing agent, the first silicon source, the first titanium source and water is (0.06-0.5): 1: (0.005-0.02): (200-2000).
Optionally, the first silicon source and the second silicon source are each an organic silicone grease, preferably, the first silicon source and the second silicon source are each independently tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate, or dimethoxydiethoxysilane, or a combination of two or three of them;
the first titanium source and the second titanium source are each independently an inorganic titanium salt and/or an organic titanate.
Optionally, in step a, the temperature of the first hydrolysis is 65-95 ℃ and the time is 3-35 hours; and/or the like and/or,
in the step b, the temperature of the first hydrothermal treatment is 120-180 ℃, and the time is 5-550 hours.
Optionally, in step c, the molar ratio of the second structure directing agent, the second silicon source, the second titanium source and the water is (1.5-5): (10-100): 1: (400-1000), the second silicon source is SiO2The second titanium source is calculated as TiO2And (6) counting.
Optionally, in step c, the temperature of the second hydrolysis is 50 to 90 ℃ and the time is 5 to 40 hours.
Optionally, in step d, the inorganic ammonium source is ammonium chloride, ammonium sulfate, ammonium oxalate, ammonium carbonate or aqueous ammonia, or a combination of two or three thereof.
Optionally, in step d, the temperature of the second hydrothermal treatment is 110-185 ℃, and the time is 5-165 hours.
Optionally, TiO in the mixed material2、SiO2And NH4 +In a molar ratio of 1: (10-200): (0-4), preferably, TiO2、SiO2And NH4 +In a molar ratio of 1: (20-100): (0.1-0.8).
Optionally, step d further comprises: collecting the second solid product, and then drying and roasting; the drying temperature is 100-200 ℃, and the drying time is 1-24 hours; the roasting temperature is 350-650 ℃, and the roasting time is 1-6 hours.
A third aspect of the present disclosure provides a titanium silicalite molecular sieve prepared using the method provided by the second aspect of the present disclosure.
A fourth aspect of the present disclosure provides a catalyst comprising a titanium silicalite molecular sieve as provided in the first or third aspect of the present disclosure.
In a fifth aspect of the present disclosure, there is provided a process for the oxidation of a macromolecular olefin to produce an epoxide using the catalyst provided in the fourth aspect of the present disclosure.
Optionally, the macromolecular olefin is cyclohexene, cyclooctene, styrene, or limonene.
Through the technical scheme, the titanium silicalite molecular sieve disclosed by the invention is rich in titanium on the surface, has proper pore diameter of most mesopores and high catalytic activity, and is favorable for improving the conversion rate of raw materials and the selectivity of a target product when being used in a process for producing an epoxy compound by a macromolecular olefin oxidation reaction.
Additional features and advantages of the disclosure will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:
FIG. 1 is a TEM electron micrograph of a titanium silicalite molecular sieve prepared in example 1 of the present disclosure;
FIG. 2 is a TEM-EDX electron micrograph of a titanium silicalite molecular sieve prepared in example 1 of the present disclosure;
fig. 3 is a schematic diagram of the mesopore size distribution of the titanium silicalite molecular sieve prepared in example 1 of the present disclosure and the titanium silicalite molecular sieve prepared in comparative example 3.
Detailed Description
The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.
The first aspect of the present disclosure provides a titanium silicalite molecular sieve, which is composed of oxygen element, silicon element and titanium element, and calculated by oxide and molar weight, TiO of the titanium silicalite molecular sieve2With SiO2In a molar ratio of 1: (20-100); the ratio of the surface titanium-silicon ratio of the titanium-silicon molecular sieve to the bulk phase titanium-silicon ratio is 1.6-3.9, and the titanium-silicon ratio refers to TiO2With SiO2The molar ratio of (A) to (B); the most probable pore diameter of the titanium-silicon molecular sieve is 15-35 nm.
According to the present disclosure, the titanium silicalite molecular sieve is an MFI-type titanium silicalite molecular sieve, an MEL-type titanium silicalite molecular sieve, or a BEA-type titanium silicalite molecular sieve. The titanium silicalite molecular sieve disclosed by the invention is rich in titanium on the surface, has a proper mesopore diameter and a most probable pore diameter, is high in catalyst activity, and can improve the conversion rate of raw materials and the selectivity of a target product when being used in a process for producing an epoxy compound by oxidizing macromolecular olefin.
In the present disclosure, the pore size can be measured according to conventional methods, which are not specifically limited in the present disclosure and are well known to those skilled in the art, such as the BET nitrogen adsorption and desorption test method. Surface titanium to silicon ratio refers to the atomic layer of TiO not more than 5nm (e.g., 1-5nm) from the surface of the titanium silicalite molecular sieve grains2With SiO2The bulk titanium-silicon ratio of (A) means TiO in the whole molecular sieve crystal grains2With SiO2In a molar ratio of (a). The surface titanium-silicon ratio and the bulk titanium-silicon ratio can be determined by methods conventionally adopted by those skilled in the art, for example, the TiO of the edge and central target point of the titanium-silicon molecular sieve can be determined by a transmission electron microscope-energy dispersive X-ray spectroscopy (TEM-EDX) method2With SiO2Molar ratio, TiO at edge targets2With SiO2TiO with the molar ratio of surface titanium to silicon and a central target point2With SiO2The molar ratio is the bulk phase titanium-silicon ratio. Alternatively, the surface titanium-silicon ratio can be determined by ion-excited etching X-ray photoelectron spectroscopy (XPS), and the bulk titanium-silicon ratio can be determined by chemical analysis or by X-ray fluorescence spectroscopy (XRF).
Preferably, the mesoporous and mode-of-diameter of the titanium silicalite molecular sieve can be 18-30nm, preferably 20-27 nm.
According to the present disclosure, the BET total specific surface area of the titanium silicalite molecular sieve can be 420-650m2The volume ratio of the mesoporous volume to the total pore volume is 40-70%. Preferably, the titanium silicalite molecular sieve has a BET total specific surface area of 430-610m2The volume ratio of the mesoporous volume to the total pore volume is 46-64 percent. The test of the total BET specific surface area in the present disclosure may be performed according to a conventional method, which is not particularly limited in the present disclosure and is well known to those skilled in the art, such as a BET nitrogen adsorption and desorption test method. The particle size of the molecular sieve may be measured by conventional methods, such as by a laser particle size analyzer, and the specific test conditions may be those routinely employed by those skilled in the art.
According to the disclosure, the titanium-silicon molecular sieve has an in-crystal multi-hollow structure, and the in-crystal multi-hollow structure can effectively improve the diffusion performance of the molecular sieve and improve the catalytic activity of the molecular sieve.
A second aspect of the present disclosure provides a method of preparing a titanium silicalite molecular sieve, the method comprising:
a. mixing a first structure directing agent, a first silicon source, a first titanium source and water, and then carrying out first hydrolysis for 2-50 hours at 40-97 ℃ to obtain a first hydrolysis mixture;
b. carrying out first hydrothermal treatment on the first hydrolysis mixture in a pressure-resistant closed container at 90-200 ℃ for 1-700 hours, and collecting a first solid product;
c. mixing a second structure directing agent, a second silicon source, a second titanium source and water, and performing second hydrolysis at 35-95 ℃ for 3-60 hours to obtain a second hydrolysis mixture;
d. mixing the first solid product, the second hydrolysis mixture and an optional inorganic ammonium source to obtain a mixed material, carrying out second hydrothermal treatment on the mixed material in a pressure-resistant closed container at 90-200 ℃ for 1-160 hours, and collecting a second solid product;
wherein the first structure directing agent is a double-head organic quaternary ammonium salt compound, or a mixture of the double-head organic quaternary ammonium salt compound and organic amine; the second structure directing agent is a single-head quaternary ammonium base compound or a mixture of the single-head quaternary ammonium base compound and organic amine;
the molar ratio of the first titanium source to the first silicon source is smaller than that of the second titanium source to the second silicon source, and the first silicon source and the second silicon source are made of SiO2The first titanium source and the second titanium source are calculated as TiO2And (6) counting.
The titanium silicalite molecular sieve prepared by the method disclosed by the invention is rich in titanium on the surface, has proper mesopore and most probable pore diameter, is high in catalyst activity, and can improve the conversion rate of raw materials and the selectivity of target products when being used in a process for producing epoxy compounds by oxidizing macromolecular olefins.
According to the present disclosure, in step a, the double-headed organic quaternary ammonium base compound and the double-headed organic quaternary ammonium salt compound have the following structures, respectively:
wherein R is1May be C3-C30 chain normal alkyl, R2May be a C1-C10 chain normal alkylene group, R3May be C1-C15 chain normal alkyl, R4、R5、R6And R7May each independently be methyl, ethyl or propyl, and X may be OH-、F-、Cl-Or Br-。
The double-headed organic quaternary ammonium base compound and the double-headed organic quaternary ammonium salt compound may be denoted as Ci-j-k-l-m-n-oX2Wherein i, j, k, l, m, n and o are sequentially represented by structural formulasR in (1)1、R2、R3、R4、R5、R6And R7X may be OH-、F-、Cl-Or Br-。
Preferably, R1Is C9-C23 chain normal alkyl, R2Is a chain normal alkylene of C6-C8, R3Is C1-C7 chain normal alkyl, R4、R5、R6And R7Each independently being methyl or ethyl, X is OH-Or Br-。
In step c, the single head quaternary ammonium base compound has the formula (R)9)3NOH，R9May be a C1-C4 alkyl group; the molecular formula of the single-head quaternary ammonium salt compound is (R)10)3NX，R10May be C1-C4 alkyl, and X may be F-、Cl-Or Br-。
According to the present disclosure, the organic amine may be a fatty amine compound, an alcohol amine compound, or an aromatic amine compound, or may be a combination of two or three thereof.
According to the present disclosure, the fatty amine compound has the general formulaR5(NH2)nWherein R is5Is C1-C4 alkyl or C1-C4 alkylene, and n is 1 or 2. Preferably, the fatty amine compound may be ethylamine, n-butylamine, butanediamine, or hexamethylenediamine, or a combination of two or three thereof.
According to the present disclosure, the alcohol amine compound has the general formula (HOR)6)mNH(3-m)Wherein R is6Is C1-C4 alkyl, and m is 1, 2 or 3. Preferably, the alkanolamine compound may be monoethanolamine, diethanolamine or triethanolamine, or may be a combination of two or three thereof.
According to the present disclosure, the aromatic amine compound may be an amine having one aromatic substituent. Preferably, the aromatic amine compound may be aniline, toluidine or p-phenylenediamine, or may be a combination of two or three thereof.
According to the present disclosure, in step a, the molar ratio of the amounts of the first structure directing agent, the first silicon source, the first titanium source and water may be (0.01-1): 1: (0.001-0.05): (50-4000), wherein the first silicon source is SiO2The first titanium source is calculated as TiO2Counting; preferably, the molar ratio of the amounts of the first structure directing agent, the first silicon source, the first titanium source and water is (0.06-0.5): 1: (0.005-0.02): (200-2000).
The first and second sources of silicon may be those commonly used in the synthesis of titanium silicalite molecular sieves well known to those skilled in the art in light of the present disclosure. In one embodiment, the first silicon source and the second silicon source may be respectively organic silicone grease, and preferably, the first silicon source and the second silicon source may be respectively and independently tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate or dimethoxydiethoxysilane, or a combination of two or three of them.
The first and second titanium sources may be conventional in the art in light of this disclosure. Preferably, the first and second titanium sources may each independently be an inorganic titanium salt, which may be titanium tetrachloride, titanium sulphate or titanium nitrate, and/or an organic titanate, which may be ethyl titanate, tetrapropyl titanate or tetrabutyl titanate.
According to the present disclosure, the temperature of the first hydrolysis in step a is preferably 65 to 95 ℃ and the time is preferably 3 to 35 hours. Both the mixing and the first hydrolysis may be carried out under stirring in order to obtain the desired effect. After the first hydrolysis, the alcohol generated by the hydrolysis of the first titanium source and the first silicon source in the reaction system may be removed to obtain the first hydrolysis mixture. The present disclosure is not particularly limited in the manner and conditions for removing the alcohol, and any known suitable manner and conditions may be used, for example, the alcohol may be removed from the reaction system by azeotropic distillation and water lost by azeotropic distillation may be replenished.
According to the present disclosure, in step b, the temperature of the first hydrothermal treatment is preferably 120-. The pressure of the first hydrothermal treatment is not particularly limited, and may be the autogenous pressure of the reaction system.
According to the present disclosure, in step c, the molar ratio of the amounts of the second structure directing agent, the second silicon source, the second titanium source and water may be (1.5-5): (10-100): 1: (400-1000), the second silicon source is SiO2The second titanium source is calculated as TiO2And (6) counting.
According to the present disclosure, the temperature of the second hydrolysis in step c is preferably 50 to 90 ℃ and the time is preferably 5 to 40 hours. Both mixing and the second hydrolysis may be carried out under stirring in order to obtain the desired effect.
According to the present disclosure, in step d, the inorganic ammonium source may be ammonium chloride, ammonium sulfate, ammonium oxalate, ammonium carbonate or aqueous ammonia, or may be a combination of two or three of them.
According to the present disclosure, the temperature of the second hydrothermal treatment in step d is preferably 110-185 ℃, and the time is preferably 5-165 hours. The pressure of the second hydrothermal treatment is not particularly limited, and may be the autogenous pressure of the reaction system. In a specific embodiment, step d may further include: the second solid product is collected, dried and calcined. The temperature of drying and roasting can vary within wide limits, preferably the temperature of drying is 100 ℃ to 200 ℃ for 1 to 24 hours; the roasting temperature is 350-650 ℃ and the roasting time is 1-6 hours. More preferably, the second solid product may be filtered, washed (optionally) and then dried and calcined. The filtration method is not particularly limited, for example, a suction filtration method can be adopted, and a washing method is not particularly limited, for example, mixed washing or rinsing can be carried out at room temperature to 50 ℃ by using water, and the water amount can be 1-20 times of the mass of the solid product.
In accordance with the present disclosure, TiO in the mixed material of step d2、SiO2And NH4 +May be 1: (10-200): (0-4), preferably, TiO2、SiO2And NH4 +In a molar ratio of 1: (20-100): (0.1-0.8).
According to the present disclosure, the temperature rising manner in any of the above steps is not particularly limited, and a temperature rising program manner, such as 0.5-1 ℃/min, may be adopted.
A third aspect of the present disclosure provides a titanium silicalite molecular sieve prepared using the method provided by the second aspect of the present disclosure.
A fourth aspect of the present disclosure provides a catalyst comprising a catalyst provided by the first aspect of the present disclosure or a titanium silicalite provided by the third aspect of the present disclosure.
In a fifth aspect of the present disclosure, there is provided a process for the oxidation of a macromolecular olefin to produce an epoxide using the catalyst provided in the fourth aspect of the present disclosure.
In one embodiment, the macromolecular olefin is cyclohexene, cyclooctene, styrene or limonene.
The present disclosure is further illustrated by the following examples, but is not to be construed as being limited thereby.
In the examples and comparative examples, the surface titanium-silicon ratio and bulk titanium-silicon ratio of the titanium-silicon molecular sieve were measured by transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDX) (the photographs are shown in fig. 2). Firstly, dispersing a sample by using ethanol, ensuring that crystal grains are not overlapped and loaded on a copper net. The sample amount is minimized during dispersion so that the particles do not overlap, and then the morphology of the sample is observed by Transmission Electron Microscopy (TEM) (the photograph is shown in FIG. 1), and individual isolated particles are randomly selected within the field of viewMaking a straight line along the diameter direction of the probe, uniformly selecting 6 measuring points with the sequence of 1, 2, 3, 4, 5 and 6 from one end to the other end, sequentially performing energy spectrum analysis on the microscopic components, and respectively measuring SiO2Content and TiO2Content of TiO calculated from the above2With SiO2The molar ratio of (a) to (b). Target TiO of titanium silicalite molecular sieve edge2With SiO2Molar ratio (TiO at 1 st measuring point and 6 th measuring point)2With SiO2Average value of molar ratio) is surface titanium-silicon ratio, and target point TiO of titanium-silicon molecular sieve center2With SiO2Molar ratio (TiO at measurement points 3 and 42With SiO2The average value of the mole ratio) is the bulk titanium-silicon ratio.
The grain size (minor axis direction) of the titanium-silicon molecular sieve is measured by a TEM-EDX method, a TEM electron microscope experiment is carried out on a Tecnai F20G2S-TWIN type transmission electron microscope of FEI company, an energy filtering system GIF2001 of Gatan company is provided, and an X-ray energy spectrometer is provided as an accessory. The electron microscope sample is prepared on a micro-grid with the diameter of 3mm by adopting a suspension dispersion method.
The BET specific surface area, pore volume and adsorption amount were measured by a nitrogen adsorption capacity method according to the BJH calculation method (see petrochemical analysis method (RIPP test method), RIPP151-90, scientific Press, 1990).
The raw materials used in the examples and comparative examples had the following properties:
tetrapropylammonium hydroxide, 20% strength by weight aqueous solution, available from Guangdong chemical plant.
Tetraethyl silicate, analytically pure, chemical reagents of the national pharmaceutical group, ltd.
Ammonia, analytically pure, 25% strength by weight aqueous solution.
Hydrogen peroxide, analytically pure, aqueous solution with concentration of 30 wt%.
The other reagents are not further explained, are all commercial products and are analytically pure.
Example 1
The titanium silicalite molecular sieve, labeled RTTS-1, is prepared as follows:
a. first Structure directing agent A, nTetraethyl silicate (TEOS), tetrabutyl titanate (TBOT) and deionized water, according to the ratio of directing agent a: TEOS: TBOT: h2O ═ 0.3: 1: 0.015: 650, adding the raw materials into a beaker in sequence, putting the beaker into a magnetic stirrer with heating and stirring functions, uniformly mixing the raw materials, stirring the mixture for 3 hours at 80 ℃, and supplementing evaporated water at any time to obtain colorless transparent hydrolysate, namely a first hydrolysis mixture.
b. And transferring the first hydrolysis mixture into a stainless steel closed reaction kettle, crystallizing at the constant temperature of 170 ℃ for 15 days, filtering a crystallized product, washing with deionized water for 10 times, wherein the water consumption is 10 times of the weight of the molecular sieve each time, placing a filter cake at 110 ℃ for drying for 24 hours, and then placing at 550 ℃ for roasting for 6 hours to obtain an intermediate titanium silicalite molecular sieve, which is marked as HS-1.
c. 25 wt% aqueous tetrapropylammonium hydroxide (TPAOH), tetraethyl orthosilicate (TEOS), tetrabutyl titanate (TBOT) and deionized water were mixed according to TPAOH: TEOS: TBOT: h2O ═ 1.8: 25: 1: weighing the raw materials according to the molar ratio of 500, sequentially adding the raw materials into a beaker, putting the beaker into a magnetic stirrer with heating and stirring functions, uniformly mixing the raw materials, stirring the mixture for 10 hours at 70 ℃ for second hydrolysis, and supplementing evaporated water at any time to obtain colorless transparent hydrolysate, namely a second hydrolysis mixture.
d. Mixing the intermediate titanium silicalite HS-1, the second hydrolysis mixture and ammonium chloride to obtain a mixed material, wherein TiO in the mixed material2、SiO2And NH4 +In a molar ratio of 1: 50: 0.3. and (3) transferring the mixed material into a stainless steel reaction kettle, carrying out second hydrothermal treatment at 170 ℃ for 24 hours, filtering, washing, drying at 120 ℃ for 24 hours, and roasting at 550 ℃ for 6 hours to obtain the titanium silicalite molecular sieve, which is recorded as RTTS-1 and prepared in the embodiment.
Wherein the structural formula of the first structure directing agent A is C22-6-6-1-1-1-1OH2. The first structure directing agent A is prepared by the following method: 1-bromodocosane (7.8g) and N, N, N ', N' -tetramethyl-1, 6-hexanediamine (34.4g) were dissolved in a volume ratio of 1:1 acetonitrile-toluene mixed solution (200 mL); the solution was then heated to 70 ℃ and held for 10 hours for the reactionShould be used. After the reaction is finished, cooling to room temperature, filtering and separating the product, and washing a filter cake with diethyl ether; the filter cake was taken out and dried in a vacuum oven at 50 ℃. 24.6g of the dried solid and 1-bromohexane (24.6g) were dissolved together in acetonitrile (300 mL); heating and refluxing the acetonitrile solution for reaction for 10 hours; after the reaction is finished, cooling to room temperature, filtering and separating the product, and washing a filter cake with diethyl ether; the filter cake was taken out and dried in a vacuum oven at 50 ℃. Dissolving the dried solid in water to obtain an aqueous solution, and performing ion exchange by using strongly basic anion exchange resin to obtain the compound C22-6-6-1-1-1-1OH2An aqueous solution.
The TEM electron micrograph of the titanium silicalite RTTS-1 is shown in FIG. 1, and the TEM-EDX electron micrograph of the RTTS-1 is shown in FIG. 2. The parameters of the titanium silicalite molecular sieve, such as the mesopore volume/total pore volume, the surface titanium-silicon ratio, and the bulk titanium-silicon ratio, are listed in table 5.
Examples 2 to 14
Titanium silicalite molecular sieves, labeled RTTS-2 to RTTS-14, were prepared according to the procedure of example 1 and the raw material ratios and synthesis conditions in tables 1 to 4, respectively. The parameters of mesopore volume/total pore volume, surface titanium to silicon ratio and bulk titanium to silicon ratio are listed in Table 5.
Comparative example 1
This comparative example illustrates the preparation of a conventional TS-1 molecular sieve according to the prior art (Zeolite, 1992, Vol.12, pp. 943 to 950).
41.6g tetraethyl orthosilicate was mixed with 24.4g aqueous tetrapropylammonium hydroxide (25.05 wt%), 95.2g deionized water was added and mixed uniformly; then hydrolyzing for 1.0h at 60 ℃ to obtain a hydrolysis solution of tetraethyl silicate. Under the action of vigorous stirring, a solution consisting of 2.0g of tetrabutyl titanate and 10.0g of isopropanol is slowly dropped into the solution, and the mixture is stirred for 3 hours at 75 ℃ to obtain a clear and transparent colloid. And then the colloid is moved into a stainless steel closed reaction kettle, and is crystallized for 3 days at the constant temperature of 170 ℃, so that a conventional TS-1 molecular sieve sample, which is marked as CTS-1, can be obtained.
Comparative example 2
This comparative example illustrates a method of preparing titanium silicalite molecular sieves according to the prior art treatment with a silylating agent (chem. Commun.,2009,11: 1407-.
Under the condition of stirring, mixing ethyl orthosilicate, tetrapropylammonium hydroxide, tetrabutyl titanate and deionized water to obtain SiO in molar ratio2: structure directing agent: TiO 22：H2O is 1: 0.2: 0.025: 50 of a homogeneous mixture; pre-crystallizing at 90 deg.C for 24 hr, and mixing with SiO2: silylation reagent ═ 1: 0.12, adding N-phenyl-triaminopropyltrimethoxysilane into the titanium silicalite molecular sieve precursor gel obtained by pre-crystallization, uniformly stirring, and transferring the obtained titanium silicalite molecular sieve precursor into a pressure-resistant stainless steel reaction kettle; heating to 170 ℃ under stirring and crystallizing for 8h under autogenous pressure. And after the stainless steel pressure-resistant reaction kettle is cooled to room temperature, recovering the obtained titanium silicalite molecular sieve which is not roasted, drying the titanium silicalite molecular sieve at 110 ℃ for 6 hours, and roasting the titanium silicalite molecular sieve at 550 ℃ for 4 hours to obtain the hierarchical pore titanium silicalite molecular sieve which is prepared by silanization and marked as CTS-2.
Comparative example 3
This comparative example illustrates the preparation of a titanium silicalite molecular sieve according to the method of example 1, except that the intermediate titanium silicalite molecular sieve used in step d is the titanium silicalite molecular sieve CTS-1 of comparative example 1, and the resulting hierarchical pore titanium silicalite molecular sieve is labeled CTS-3.
TABLE 1
TABLE 2
TABLE 3
TABLE 4
TABLE 5
Test example
The samples RTTS-1 to RTTS-14 obtained in examples 1 to 14 and the molecular sieve samples CTS-1 to CTS-3 obtained by the method of comparative example were tested for their catalytic effects on the ketoneamino oximation reaction.
The epoxidation reaction of cyclohexene is carried out in a three-mouth bottle reaction device with an automatic temperature control water bath, magnetic stirring and condensation reflux system. And (3) respectively adding the samples obtained in the above embodiments and the molecular sieve samples obtained by the method of the comparative example into a three-neck flask according to 1g of molecular sieve catalyst, 0.1moL of cyclohexene and 0.1moL of hydrogen peroxide in sequence, placing the three-neck flask into a water bath kettle with the preset reaction temperature, reacting at 60 ℃ for 2 hours, and cooling to stop the reaction after the reaction is finished. The product was sampled and the composition of the product was determined on an Agilent 6890N chromatograph using HP-5 capillary column and quantified by the calibrated normalization method, the results of which are shown in Table 6.
The cyclohexene conversion rate and the cyclohexene oxide selectivity are respectively calculated according to the following formulas:
conversion of cyclohexene [ (M)0-MCHO)/M0]×100％
Cyclohexene oxide selectivity [ M ═ MCHOX/(M0-MCHO)]×100％
Wherein the mass of the initial cyclohexene is denoted as M0The mass of unreacted cyclohexene is denoted MCHOThe mass of the epoxycyclohexane is designated as MCHOX。
TABLE 6
Numbering
Cyclohexene conversion rate%
Selectivity for epoxycyclohexane%
Example 1
99.78
99.55
Example 2
82.05
84.10
Example 3
81.27
83.09
Example 4
96.58
99.05
Example 5
98.88
97.89
Example 6
99.55
98.47
Example 7
98.65
98.79
Example 8
99.14
98.22
Example 9
99.22
98.78
Example 10
98.85
97.25
Example 11
98.25
98.8
Example 12
98.88
97.25
Example 13
95.69
96.21
Example 14
92.89
93.33
Comparative example 1
62.31
87.23
Comparative example 2
45.36
52.86
Comparative example 3
69.25
88.25
As can be seen from table 6, the titanium silicalite molecular sieve disclosed in the present disclosure has high catalytic activity, and when the titanium silicalite molecular sieve is used in a process for producing an epoxy compound by oxidizing a macromolecular olefin, the conversion rate of raw materials and the selectivity of a target product can be improved.
The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.
It should be noted that, in the foregoing embodiments, various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various combinations that are possible in the present disclosure are not described again.
In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.