Core-shell structure titanium-silicon material, preparation method thereof and method for producing ketoxime through macromolecular ketone ammoximation reaction
阅读说明：本技术 核壳结构钛硅材料及其制备方法和大分子酮类氨肟化反应生产酮肟的方法 (Core-shell structure titanium-silicon material, preparation method thereof and method for producing ketoxime through macromolecular ketone ammoximation reaction ) 是由 杨永佳 朱斌 林民 夏长久 彭欣欣 罗一斌 舒兴田 于 2019-10-31 设计创作，主要内容包括：本公开涉及一种核壳结构钛硅材料及其制备方法和大分子酮类氨肟化反应生产酮肟的方法,内核为具有晶内多空心结构的全硅分子筛,外壳为钛硅分子筛,以氧化物计并以摩尔量计,核壳结构钛硅材料的TiO-2与SiO-2的摩尔比为1：(30-100)；核壳结构钛硅材料的表面钛硅比与体相钛硅比的比值为2.0-4.5,钛硅比是指TiO-2与SiO-2的摩尔比；核壳结构钛硅材料进行BET氮气吸脱附测试时,p/p-0为0.8时核壳结构钛硅材料的吸附量与p/p-0为0.2时核壳结构钛硅材料的吸附量的差值记为ΔV,ΔV为23-45mL/g。本公开的核壳结构钛硅材料的外壳表面富钛且具有开阔孔结构,将其用于大分子酮类氨肟化反应生产酮肟工艺中可以提高原料转化率和目标产物选择性,并提高氧化剂过氧化氢的利用率。(The invention relates to a core-shell structure titanium-silicon material, a preparation method thereof and a method for producing ketoxime by macromolecular ketone ammoximation reaction, wherein the inner core is an all-silicon molecular sieve with an in-crystal multi-hollow structure, the shell is a titanium-silicon molecular sieve, and TiO of the core-shell structure titanium-silicon material is calculated by oxides and calculated by mol 2 With SiO 2 In a molar ratio of 1: (30-100); the ratio of the surface titanium-silicon ratio of the core-shell structure titanium-silicon material to the bulk titanium-silicon ratio is 2.0-4.5, wherein the titanium-silicon ratio refers to TiO 2 With SiO 2 The molar ratio of (A) to (B); when the core-shell structure titanium silicon material is subjected to BET nitrogen adsorption and desorption test, p/p 0 When the adsorption quantity is 0.8, the adsorption quantity and p/p of the core-shell structure titanium silicon material 0 When the adsorption capacity of the core-shell structure titanium-silicon material is 0.2, the difference is recorded as delta V, and the delta V is 23-45 mL/g. The shell surface of the core-shell structure titanium-silicon material disclosed by the invention is rich in titanium and has a wide pore structure, and when the core-shell structure titanium-silicon material is used in a process for producing ketoxime by a macromolecular ketone ammoximation reaction, the conversion rate of raw materials and the selectivity of a target product can be improved, and the utilization rate of oxidant hydrogen peroxide is improved.)
1. The core-shell structure titanium-silicon material is characterized by comprising an inner core and an outer shell, wherein the inner core is an all-silicon molecular sieve with an in-crystal multi-hollow structure, the outer shell is a titanium-silicon molecular sieve, and TiO of the core-shell structure titanium-silicon material is calculated by oxides and calculated by mole2With SiO2In a molar ratio of 1: (30-100); the ratio of the surface titanium-silicon ratio of the core-shell structure titanium-silicon material to the bulk titanium-silicon ratio is 2.0-4.5, wherein the titanium-silicon ratio refers to TiO2With SiO2The molar ratio of (A) to (B); when the core-shell structure titanium-silicon material is subjected to BET nitrogen adsorption and desorption test, p/p0When the adsorption quantity is 0.8, the adsorption quantity and p/p of the core-shell structure titanium-silicon material0When the adsorption capacity of the core-shell structure titanium-silicon material is 0.2, the difference is recorded as delta V, and the delta V is 23-45 mL/g.
2. The core-shell structure titanium-silicon material according to claim 1, wherein Δ V is 26-38 mL/g.
3. The core-shell structure titanium-silicon material as recited in claim 1, wherein the BET total specific surface area of the core-shell structure titanium-silicon material is 400-600m2The volume ratio of the mesoporous volume to the total pore volume is 50-70%.
4. A method for preparing a core-shell structure titanium-silicon material is characterized by comprising the following steps:
a. mixing a first structure directing agent, a first silicon source and water, and performing first hydrolysis at 40-97 ℃ for 2-50 hours to obtain a first hydrolysis mixture;
b. mixing the first hydrolysis mixture obtained in the step a with a carbon-containing porous material, performing first hydrothermal treatment for 1-600 hours at 90-200 ℃ in a pressure-resistant closed container, and collecting a first solid product;
c. mixing the second structure directing agent, a second silicon source, a titanium source and water, and performing second hydrolysis at 35-95 ℃ for 3-60 hours to obtain a second hydrolysis mixture;
d. and mixing the first solid product and the second hydrolysis mixture to obtain a mixed material, carrying out second hydrothermal treatment on the mixed material in a pressure-resistant closed container at 90-200 ℃ for 1-168 hours, collecting a second solid product, drying and roasting.
5. The method of claim 4, wherein the carbon-containing porous material is carbon nanotubes, carbon nanofibers, cracked carbon black, or semi-coke based activated carbon, or a combination of two or three thereof;
preferably, the carbon-containing porous material is semi-coke-based activated carbon or carbon nanotubes.
6. The method of claim 4, wherein the first and second structure directing agents are each independently a quaternary ammonium base compound;
the quaternary ammonium base compound is tetraethylammonium hydroxide, tetrapropylammonium hydroxide or tetrabutylammonium hydroxide.
7. The method of claim 4, wherein the first structure directing agent and the second structure directing agent are each independently a mixture of a quaternary ammonium salt compound and one or more of a quaternary ammonium base compound, a fatty amine compound, an alcohol amine compound, and an aromatic amine compound;
the quaternary ammonium base compound is tetrapropylammonium hydroxide, and the quaternary ammonium salt compound is tetrapropylammonium chloride and/or tetrapropylammonium bromide; alternatively, the first and second electrodes may be,
the quaternary ammonium base compound is tetrabutylammonium hydroxide, and the quaternary ammonium salt compound is tetrabutylammonium chloride and/or tetrabutylammonium bromide; alternatively, the first and second electrodes may be,
the quaternary ammonium base compound is tetraethylammonium hydroxide, and the quaternary ammonium salt compound is tetraethylammonium chloride and/or tetraethylammonium bromide.
8. The method of claim 7, 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.
9. The method of claim 4, wherein in step a, the molar ratio of the amounts of the first structure directing agent, the first silicon source, and water is (0.05-1.5): 1: (10-400), preferably (0.1-0.8): 1: (30-200), wherein the first silicon source is SiO2And (6) counting.
10. The method according to claim 4, wherein the first and second silicon sources are each an organosilicate, preferably each independently selected from tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate, or dimethoxydiethoxysilane, or a combination of two or three thereof;
and c, the titanium source is inorganic titanium salt and/or organic titanate.
11. The method as claimed in claim 4, wherein the carbon-containing porous material is used in the amount of 0.01-0.5 molar parts in step b with respect to 1 molar part of the first silicon source, which is SiO2The carbon-containing porous material is calculated by carbon element;
preferably, the carbon-containing porous material is used in an amount of 0.05 to 0.3 parts by mole with respect to 1 part by mole of the first silicon source.
12. The process of claim 4, wherein in step a, the temperature of the first hydrolysis is 50-95 ℃ and the time is 1-15 h; and/or the like and/or,
in the step b, the temperature of the first hydrothermal treatment is 120-180 ℃, and the time is 5-485 h.
13. The method of claim 4, wherein in step c, the second structure directing agent, the silicon source, the titanium source and the water are used in a molar ratio of (0.1-10): (1-100): 1: (100-2000), preferably (1.5-5): (10-40): 1: (400-1000), the second silicon source is SiO2The titanium source is calculated as TiO2And (6) counting.
14. The process according to claim 4, wherein in step c, the temperature of the second hydrolysis is 55-90 ℃ for 5-40 hours.
15. The method as claimed in claim 4, wherein the temperature of the second hydrothermal treatment in step d is 110-180 ℃ for 5-120 hours.
16. The method of claim 4, wherein in step d, TiO is in the mixed material2And SiO2In a molar ratio of 1: (10-200), preferably, TiO2And SiO2In a molar ratio of 1: (20-100).
17. The method as claimed in claim 4, wherein in step d, 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.
18. The core-shell structure titanium-silicon material prepared by the method of any one of claims 4 to 17.
19. A catalyst comprising the core-shell titanium silicalite material of any one of claims 1 to 4 and claim 18.
20. A process for producing a ketoxime by ammoximation of a macromolecular ketone, which comprises using the catalyst according to claim 19.
21. The method of claim 20, wherein the macromolecular ketone is cyclohexanone, cyclopentanone, cyclododecanone, or acetophenone.
Technical Field
The invention relates to a core-shell structure titanium-silicon material, a preparation method thereof and a method for producing ketoxime through macromolecular ketone ammoximation reaction.
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, good selectivity of oxidation products and the like in the oxidation reaction of organic mattersAnd (4) point. 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.
Disclosure of Invention
The surface of the core-shell structure titanium-silicon material disclosed by the invention is rich in titanium and has an open pore structure, and the core-shell structure titanium-silicon material can improve the conversion rate of raw materials and the selectivity of a target product and improve the utilization rate of an oxidant hydrogen peroxide when being used in a process for producing ketoxime by a macromolecular ketone ammoximation reaction, and is particularly suitable for a phenylacetone ammoximation reaction.
In order to achieve the above object, the disclosure provides, in a first aspect, a core-shell structure titanium-silicon material, which includes an inner core and an outer shell, where the inner core is an all-silicon molecular sieve having an intra-crystal multi-hollow structure, and the outer shell is a titanium-silicon molecular sieve, and the TiO of the core-shell structure titanium-silicon material is calculated as an oxide and calculated as a molar amount2With SiO2In a molar ratio of 1: (30-100); the ratio of the surface titanium-silicon ratio of the core-shell structure titanium-silicon material to the bulk titanium-silicon ratio is 2.0-4.5, wherein the titanium-silicon ratio refers to TiO2With SiO2The molar ratio of (A) to (B); when the core-shell structure titanium-silicon material is subjected to BET nitrogen adsorption and desorption test, p/p0When the adsorption quantity is 0.8, the adsorption quantity and p/p of the core-shell structure titanium-silicon material0When the adsorption capacity of the core-shell structure titanium-silicon material is 0.2, the difference is recorded as delta V, and the delta V is 23-45 mL/g.
Alternatively, Δ V is from 26 to 38 mL/g.
Optionally, the BET total specific surface area of the core-shell structure titanium-silicon material is 400-600m2The volume ratio of the mesoporous volume to the total pore volume is 50-70%.
The second aspect of the present disclosure provides a method for preparing a core-shell titanium-silicon material, including:
a. mixing a first structure directing agent, a first silicon source and water, and performing first hydrolysis at 40-97 ℃ for 2-50 hours to obtain a first hydrolysis mixture;
b. mixing the first hydrolysis mixture obtained in the step a with a carbon-containing porous material, performing first hydrothermal treatment for 1-600 hours at 90-200 ℃ in a pressure-resistant closed container, and collecting a first solid product;
c. mixing the second structure directing agent, a second silicon source, a titanium source and water, and performing second hydrolysis at 35-95 ℃ for 3-60 hours to obtain a second hydrolysis mixture;
d. and mixing the first solid product and the second hydrolysis mixture to obtain a mixed material, carrying out second hydrothermal treatment on the mixed material in a pressure-resistant closed container at 90-200 ℃ for 1-168 hours, collecting a second solid product, drying and roasting.
Optionally, the carbon-containing porous material is carbon nano tube, carbon nano fiber, cracked carbon black or semi-coke-based activated carbon, or a combination of two or three of the carbon nano fiber, the cracked carbon black and the semi-coke-based activated carbon;
preferably, the carbon-containing porous material is semi-coke-based activated carbon or carbon nanotubes.
The first structure directing agent and the second structure directing agent are each independently a quaternary ammonium base compound;
optionally, the quaternary ammonium base compound is tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrabutylammonium hydroxide.
Optionally, the first structure directing agent and the second structure directing agent are each independently a mixture of a quaternary ammonium salt compound and one or more of a quaternary ammonium base compound, a fatty amine compound, an alcohol amine compound, and an aromatic amine compound;
the quaternary ammonium base compound is tetrapropylammonium hydroxide, and the quaternary ammonium salt compound is tetrapropylammonium chloride and/or tetrapropylammonium bromide; alternatively, the first and second electrodes may be,
the quaternary ammonium base compound is tetrabutylammonium hydroxide, and the quaternary ammonium salt compound is tetrabutylammonium chloride and/or tetrabutylammonium bromide; alternatively, the first and second electrodes may be,
the quaternary ammonium base compound is tetraethylammonium hydroxide, and the quaternary ammonium salt compound is tetraethylammonium chloride and/or tetraethylammonium bromide.
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 amounts of the first structure directing agent, the first silicon source and water is (0.05-1.5): 1: (10-400), preferably (0.1-0.8): 1: (30-200), wherein the first silicon source is SiO2And (6) counting.
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 selected from tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate, or dimethoxydiethoxysilane, or a combination of two or three of them;
and c, the titanium source is inorganic titanium salt and/or organic titanate.
Optionally, the carbon-containing porous material in step b is used in an amount of 0.01 to 0.5 molar parts relative to 1 molar part of the first silicon source, which is SiO2The carbon-containing porous material is calculated by carbon element;
preferably, the carbon-containing porous material is used in an amount of 0.05 to 0.3 parts by mole with respect to 1 part by mole of the first silicon source.
Optionally, in step a, the temperature of the first hydrolysis is 50-95 ℃ and the time is 1-15 h; and/or the like and/or,
in the step b, the temperature of the first hydrothermal treatment is 120-180 ℃, and the time is 5-485 h.
Optionally, in step c, the molar ratio of the amounts of the second structure directing agent, the silicon source, the titanium source and the water is (0.1-10): (1-100): 1: (100-2000), preferably (1.5-5): (10-40): 1: (400-1000), the second silicon source is SiO2The titanium source is calculated as TiO2And (6) counting.
Optionally, in step c, the temperature of the second hydrolysis is 55-90 ℃ and the time is 5-40 hours.
Optionally, in the step d, the temperature of the second hydrothermal treatment is 110-.
Optionally, in step d, TiO in the mixed material2And SiO2In a molar ratio of 1: (10-200), preferably, TiO2And SiO2In a molar ratio of 1: (20-100).
Optionally, in the step d, 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.
The third aspect of the disclosure provides a core-shell structure titanium-silicon material prepared by the method provided by the second aspect of the disclosure.
The fourth aspect of the present disclosure provides a catalyst containing the core-shell structure titanium-silicon material provided in the first or third aspect of the present disclosure.
In a fifth aspect of the present disclosure, a method for producing ketoxime by a macromolecular ketone ammoximation reaction is provided, wherein the method uses the catalyst provided by the fourth aspect of the present disclosure.
Optionally, the macromolecular ketone is cyclohexanone, cyclopentanone, cyclododecanone, or acetophenone.
Through the technical scheme, the surface of the core-shell structure titanium-silicon material is rich in titanium and has an open pore structure, the inner core is an all-silicon molecular sieve, non-framework titanium is not generated, and the titanium material can be saved. The method can improve the conversion rate of raw materials and the selectivity of target products and improve the utilization rate of oxidant hydrogen peroxide when being used in the process of producing ketoxime by macromolecular ketone ammoximation reaction, and is particularly suitable for the acetophenone ammoximation 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 low temperature nitrogen adsorption-desorption graph of an intermediate all-silica molecular sieve prepared in example 1 of the present disclosure.
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 disclosure provides a core-shell structure titanium-silicon material, which includes an inner core and an outer shell, wherein the inner core is an all-silicon molecular sieve with an intra-crystal multi-hollow structure, and the outer shell is a titanium-silicon molecular sieve, and calculated by oxides and calculated by mol, the TiO of the core-shell structure titanium-silicon material2With SiO2In a molar ratio of 1: (30-100); the ratio of the surface titanium-silicon ratio of the core-shell structure titanium-silicon material to the bulk titanium-silicon ratio is 2.0-4.5, wherein the titanium-silicon ratio refers to TiO2With SiO2The molar ratio of (A) to (B); when the core-shell structure titanium silicon material is subjected to BET nitrogen adsorption and desorption test, p/p0When the adsorption quantity is 0.8, the adsorption quantity and p/p of the core-shell structure titanium silicon material0When the adsorption capacity of the core-shell structure titanium-silicon material is 0.2, the difference is recorded as delta V, and the delta V is 23-45 mL/g.
Wherein, p/p0It is the ratio of the nitrogen partial pressure to the saturated vapor pressure of liquid nitrogen at the adsorption temperature in the BET nitrogen adsorption and desorption test. According to the present disclosure, the molecular sieve is an MFI-type molecular sieve, an MEL-type molecular sieve, or a BEA-type molecular sieve. The titanium-silicon material with the structure is rich in titanium on the surface, has a wide pore structure, saves titanium materials and can avoid non-skeleton titanium, the titanium-silicon material can improve the conversion rate of raw materials and the selectivity of target products and improve the utilization rate of oxidant hydrogen peroxide when being used in the process of producing ketoxime by macromolecular ketone ammoximation reaction, and is particularly suitable for the acetophenone ammoximation reaction.
In the present disclosure, the BET nitrogen adsorption and desorption test can be performed according to a conventional method, which is not specifically limited in the present disclosure and is well known to those skilled in the art, for example, using N2Static adsorption and the like. 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 refers to the T of the whole molecular sieve crystal grainsiO2With 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, Δ V is from 26 to 38mL/g, more preferably from 28 to 35 mL/g.
According to the disclosure, the BET total specific surface area of the core-shell structure titanium-silicon material can be 400-600m2The volume ratio of the mesoporous volume to the total pore volume can be 50-70%. Preferably, the BET total specific surface area of the titanium silicalite molecular sieve can be 440-500m2The volume ratio of the mesoporous volume to the total pore volume can be 55-65%. The BET total specific surface area and pore volume measurements in the present disclosure may be made according to conventional methods, and are not specifically limited in this disclosure and are well known to those skilled in the art, for example, using the 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.
The second aspect of the present disclosure provides a method for preparing a core-shell titanium-silicon material, including:
a. mixing a first structure directing agent, a first silicon source and water, and performing first hydrolysis at 40-97 ℃ for 2-50 hours to obtain a first hydrolysis mixture;
b. mixing the first hydrolysis mixture obtained in the step a with a carbon-containing porous material, performing first hydrothermal treatment for 1-600 hours at 90-200 ℃ in a pressure-resistant closed container, and collecting a first solid product;
c. mixing the second structure directing agent, a second silicon source, a 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 and the second hydrolysis mixture to obtain a mixed material, carrying out second hydrothermal treatment on the mixed material in a pressure-resistant closed container at 90-200 ℃ for 1-168 hours, collecting the second solid product, drying and roasting.
The core-shell structure titanium-silicon material prepared by the method has an all-silicon molecular sieve with an in-crystal multi-hollow structure as an inner core, and a titanium-silicon molecular sieve as an outer shell, wherein the surface of the titanium-silicon molecular sieve is rich in titanium, free of non-framework titanium and provided with an open pore structure, and when the titanium-silicon molecular sieve is used in a process for producing ketoxime by a macromolecular ketone ammoximation reaction, the conversion rate of raw materials and the selectivity of a target product can be improved, the utilization rate of oxidant hydrogen peroxide is improved, and the titanium-silicon material is particularly suitable for.
According to the present disclosure, the carbon-containing porous material may be carbon nanotubes, carbon nanofibers, cracked carbon black, or semi-coke-based activated carbon, or may be a combination of two or three of them. Preferably, the carbon-containing porous material is semi-coke-based activated carbon or carbon nanotubes. The semi-coke-based activated carbon is an activated carbon material with uniform micropores, which is prepared by an activation method combining chemical etching and physical dredging with semi-coke, the surface structure of the activated carbon material is rich in hydroxyl, and the specific surface area is 300-1000m2(iv)/g, median pore diameter of 0.3-20 nm.
In accordance with the present disclosure, the structure directing agent can be a common type of synthetic titanium silicalite molecular sieve, and in one embodiment, the first structure directing agent and the second structure directing agent can each independently be a quaternary ammonium base compound. In another embodiment, the first structure directing agent and the second structure directing agent may each independently be a mixture of a quaternary ammonium salt compound and one or more of a quaternary ammonium base compound, a fatty amine compound, an alcohol amine compound, and an aromatic amine compound.
According to an embodiment of the present disclosure, the first structure directing agent and the second structure directing agent may be tetrapropylammonium hydroxide, respectively, or may be a mixture of tetrapropylammonium chloride and/or tetrapropylammonium bromide and one or more selected from quaternary ammonium base compounds, aliphatic amine compounds, alcohol amine compounds, and aromatic amine compounds, respectively. In the prepared core-shell structure titanium-silicon material, the inner core is a Silicalite-1 molecular sieve, and the outer shell is a TS-1 molecular sieve. Further, when the structure directing agent is a mixture of tetrapropylammonium chloride and/or tetrapropylammonium bromide and one or more selected from the group consisting of a quaternary ammonium base compound, a fatty amine compound, an alcohol amine compound, and an aromatic amine compound, the molar ratio of tetrapropylammonium chloride and/or tetrapropylammonium bromide to one or more of the quaternary ammonium base compound, the fatty amine compound, the alcohol amine compound, and the aromatic amine compound may be 1: (0.1-5).
In another embodiment, the first structure directing agent and the second structure directing agent may be tetrabutylammonium hydroxide, respectively, or a mixture of tetrabutylammonium chloride and/or tetrabutylammonium bromide, and one or more selected from the group consisting of quaternary ammonium base compounds, fatty amine compounds, alcohol amine compounds, and aromatic amine compounds, each independently. In the prepared core-shell structure titanium-silicon material, the inner core is a Silicalite-2 molecular sieve, and the outer shell is a TS-2 molecular sieve. Further, when the structure directing agent is a mixture of tetrabutylammonium chloride and/or tetrabutylammonium bromide and one or more selected from the group consisting of a quaternary ammonium base compound, a fatty amine compound, an alcohol amine compound, and an aromatic amine compound, the molar ratio of tetrabutylammonium chloride and/or tetrabutylammonium bromide to one or more of the quaternary ammonium base compound, the fatty amine compound, the alcohol amine compound, and the aromatic amine compound may be 1: (0.2-7).
In another embodiment, the first structure directing agent and the second structure directing agent may each be tetraethylammonium hydroxide, or may each independently be a mixture of tetraethylammonium chloride and/or tetraethylammonium bromide with one or more compounds selected from the group consisting of quaternary ammonium base compounds, fatty amine compounds, alcohol amine compounds, and aromatic amine compounds. In the prepared core-shell titanium-silicon material, the inner core is a Silicalite-beta molecular sieve, and the outer shell is a TS-beta molecular sieve. Further, when the structure directing agent is a mixture of tetraethylammonium chloride and/or tetraethylammonium bromide and one or more selected from the group consisting of quaternary ammonium base compounds, fatty amine compounds, alcohol amine compounds, and aromatic amine compounds, the molar ratio of tetraethylammonium chloride and/or tetraethylammonium bromide to one or more of the quaternary ammonium base compounds, fatty amine compounds, alcohol amine compounds, and aromatic amine compounds may be 1: (0.07-0.8).
According to the present disclosure, the fatty amine compound has the general formula R5(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 and water may be (0.05-1.5): 1: (10-400), wherein the first silicon source is SiO2And (6) counting. Preferably, the molar ratio of the amounts of the first structure directing agent, the first silicon source and water may be (0.1-0.8): 1: (30-200).
The first and second silicon sources may be those commonly used for synthesizing titanium silicalite molecular sieves well known to those skilled in the art in light of the present disclosure, and the present disclosure is not particularly limited thereto. In one embodiment, the first and second silicon sources may be organosilicates, and preferably, each of the first and second silicon sources is independently selected from tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate, or dimethoxydiethoxysilane, or a combination of two or three thereof.
The titanium source may be a conventional choice in the art in light of this disclosure. Preferably, the titanium source may be an inorganic titanium salt and/or an organic titanate. For example, the organic titanate may be ethyl titanate, tetrapropyl titanate or tetrabutyl titanate, and the inorganic titanium salt may be, for example, titanium tetrachloride, titanium sulfate or titanium nitrate, or a hydrolysate of titanium tetrachloride, titanium sulfate or titanium nitrate.
According to the present disclosure, the carbon-containing porous material may be used in step b in an amount of 0.01 to 0.5 molar parts, preferably 0.05 to 0.3 molar parts, relative to 1 molar part of the first silicon source, which is SiO2The carbon-containing porous material is calculated by carbon element.
According to the present disclosure, the temperature of the first hydrolysis in step a may preferably be 50-95 ℃ and the time is preferably 1-15 h. 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 titanium source and the water may be (0.1-10): (1-100): 1: (100-2000), the second silicon source is SiO2The titanium source is calculated as TiO2And (6) counting. Preferably, is (1.5-5): (10-40): 1: (400-1000).
According to the present disclosure, the temperature of the second hydrolysis in step c is preferably 55-90 ℃ and the time is preferably 5-40 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 temperature of the second hydrothermal treatment is preferably 110-. The pressure of the second hydrothermal treatment is not particularly limited, and may be the autogenous pressure of the reaction system. In the step d, the obtained second solid product is dried and roasted to obtain the titanium silicalite molecular sieve. 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. According to the present disclosure, the temperature of drying and baking can vary within a wide range, preferably, the temperature of drying can be 100-; the temperature for calcination can be 350-650 deg.C, and the time can be 1-6 hours.
In accordance with the present disclosure, TiO in the mixed material of step d2And SiO2May be 1: (100-200), preferably, TiO2And SiO2In a molar ratio of 1: (20-100).
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.
In a third aspect of the disclosure, a core-shell structure titanium-silicon material prepared by the method provided in the second aspect of the disclosure is provided.
The fourth aspect of the present disclosure provides a catalyst containing the core-shell structure titanium-silicon material provided in the first aspect of the present disclosure or the third aspect of the present disclosure.
In a fifth aspect of the present disclosure, a method for producing ketoxime by a macromolecular ketone ammoximation reaction is provided, wherein the method uses the catalyst provided by the fourth aspect of the present disclosure.
In one embodiment, the macromolecular ketone is cyclohexanone, cyclopentanone, cyclododecanone, or acetophenone.
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 titanium-silicon molecular sieveThe measurement was carried out by a transmission electron microscopy-energy dispersive X-ray spectroscopy elemental analysis (TEM-EDX) method (the photograph is 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 reduced as much as possible during dispersion so that the particles are not superposed together, then the appearance of the sample is observed through a Transmission Electron Microscope (TEM), single isolated particles are randomly selected in a field of view and made into a straight line along the diameter direction of the particles, 6 measuring points with the sequence of 1, 2, 3, 4, 5 and 6 are uniformly selected from one end to the other end, the energy spectrum analysis microcosmic composition is sequentially carried out, and the SiO is respectively measured2Content 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 and pore volume 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. tetrapropylammonium hydroxide (TPAOH) aqueous solution having a concentration of 25 wt.%, Tetraethylorthosilicate (TEOS), and deionized water were mixed in the following ratio by TPAOH: TEOS: h2O ═ 0.4: 1: the raw materials are weighed according to the molar ratio of 100 and are sequentially added into a beaker. Putting the mixture into a magnetic stirrer with heating and stirring functions, uniformly mixing, stirring at 85 ℃ for 4 hours for first hydrolysis, and supplementing evaporated water at any time to obtain colorless transparent hydrolysate, namely a first hydrolysis mixture.
b. Adding semi-coke-based activated carbon to the first hydrolysis mixture during stirring, wherein SiO is2: semi-coke-based activated carbon 1: 0.15. transferring the mixed semi-coke-based activated carbon and the first hydrolysis mixture into a stainless steel closed reaction kettle, carrying out first hydrothermal treatment for 24 hours at 170 ℃, filtering the product, washing the product with deionized water for 10 times, wherein the water consumption is 10 times of the weight of the molecular sieve each time, placing the filter cake at 110 ℃ for drying for 24 hours, and then placing at 550 ℃ for roasting for 6 hours to obtain an intermediate all-silicon molecular sieve, which is marked as HS-1. The low-temperature nitrogen adsorption-desorption curve chart of the intermediate full-silicon molecular sieve is shown in figure 3.
c. 25 wt% aqueous tetrapropylammonium hydroxide (TPAOH), Tetraethylorthosilicate (TEOS), tetrabutyltitanate (TBOT) and deionized water were mixed as TPAOH: TEOS: TBOT: h2O is 2: 15: 1: weighing raw materials according to the molar ratio of 400, 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. And mixing the intermediate all-silicon molecular sieve HS-1 with the second hydrolysis mixture, transferring the mixture 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-silicon molecular sieve, which is marked as RTTS-1 and prepared in the embodiment.
The preparation method of the semi-coke-based activated carbon comprises the following steps: mechanically grinding commercial industrial semi-coke to 16-20 meshes, weighing 15g of semi-coke powder, mixing KOH accounting for 10 wt% of the semi-coke, 5g of an activating auxiliary agent and 15g of water to prepare a soaking solution, carrying out etching activation treatment on the semi-coke powder for 24 hours, then transferring the semi-coke powder into a stainless steel reaction tube, carrying out dredging activation treatment by raising the temperature to 200 ℃ in a flowing water vapor atmosphere, cooling, taking out the solid, washing and filtering the solid by using a 5 wt% hydrochloric acid solution, washing the solid to be neutral by using deionized water, and drying the solid at 106 ℃ for one day to obtain the semi-coke-based activated carbon.
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 mesoporous volume/total pore volume, the surface titanium-silicon ratio and the bulk titanium-silicon ratio are shown 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 the preparation of titanium silicalite molecular sieves according to the current method of hard templating agents (chem. Commun.,2000, 2157-2158.).
Adopting tetrapropylammonium hydroxide, ethanol and deionized water to carry out primary wet impregnation on BP700 carbon black particles (18nm), then after the ethanol is volatilized, mixing the carbon black particles with tetraethoxysilane, tetrapropylammonium hydroxide, tetraethyl titanate and deionized water under the stirring condition to obtain TPA (terephthalic acid) with the molar ratio2O：TiO2：SiO2：H2O20: 1: 100: 200, and aging for 3 hours; transferring the aging solution to a pressure-resistant stainless steel reaction kettle; heating to 170 ℃ under stirring and crystallizing for 72h 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 10 hours, and roasting the titanium silicalite molecular sieve at 550 ℃ for 8 hours to obtain the hierarchical pore titanium silicalite molecular sieve marked as CTS-2.
Comparative example 3
This comparative example illustrates a process for preparing an all-silicon molecular sieve according to the prior art.
23.1g of tetraethyl silicate was mixed with 22.1g of an aqueous tetrapropyl ammonium hydroxide solution (concentration: 25% by weight), and 7.2g of deionized water was added and mixed uniformly; the mixture was then stirred at 75 ℃ to drive off the alcohol for 6 hours with vigorous stirring to give a clear and transparent colloid. Then the colloid is transferred into a stainless steel closed reaction kettle and crystallized for 3 days at the constant temperature of 170 ℃; the obtained sample is filtered, washed, dried at 110 ℃ and roasted at 550 ℃ to obtain the all-silicon S-1 molecular sieve which is marked as CTS-3.
Comparative example 4
This comparative example illustrates the preparation of a titanium silicalite molecular sieve according to the method of example 1, except that the first solid product used in step d is the all-silica molecular sieve CTS-4 prepared in comparative example 3, and the resulting multi-stage pore titanium silicalite molecular sieve is designated CTS-4.
TABLE 1
TABLE 2
TABLE 3
TABLE 4
TABLE 5
Test example
This test example demonstrates the catalytic effect of CSTS-1 to RTTS-14 samples obtained in examples 1 to 14 of the present invention and CTS-1 to CTS-4 molecular sieve samples obtained by the method of comparative example on the ketoxime reaction of acetophenone.
The acetophenone oxamidination reaction was carried out in a 250mL three-necked flask reaction apparatus with an automatic temperature-controlled water bath, magnetic stirring and a condensate reflux system. Adding 1.96g of molecular sieve catalyst, 39g of solvent ethanol, 27.2g of ammonia water (mass fraction of 25%) and 19.6g of acetophenone into a three-mouth bottle in sequence, placing the three-mouth bottle into a water bath kettle with preset reaction temperature, slowly adding 27.2g of hydrogen peroxide (mass fraction of 30%) into a reaction system, and cooling to stop reaction after the reaction is finished. Adding a certain amount of ethanol into the reaction solution for homogeneous phase, filtering and separating liquid from solid, adding a certain amount of internal standard substance into the filtrate, measuring the product composition of the obtained product on an Agilent 6890N chromatograph by using an HP-5 capillary column, and calculating the result according to an internal standard method without integrating the solvent ethanol, wherein the result is shown in Table 6.
The conversion rate of acetophenone and selectivity of acetophenone oxime are calculated according to the following formulas:
conversion of acetophenone [ [ (M)0-MCHO)/M0]×100％
Acetophenone oxime selectivity ═ MCHOX/(M0-MCHO)]×100％
Wherein the initial amount of acetophenone is designated M0The mass of unreacted acetophenone is designated MCHOThe mass of the acetophenone oxime is marked as MCHOX。
TABLE 6
Numbering
Conversion of acetophenone,% of
Acetophenone oxime selectivity,%
Example 1
99.93
99.62
Example 2
93.28
97.41
Example 3
90.04
94.20
Example 4
97.58
95.89
Example 5
97.89
96.78
Example 6
96.52
94.33
Example 7
99.89
99.85
Example 8
96.52
97.12
Example 9
99.05
99.02
Example 10
99.89
99.48
Example 11
99.8
98.99
Example 12
99.02
97.06
Example 13
98.87
97.92
Example 14
93.25
93.54
Comparative example 1
62.31
87.23
Comparative example 2
45.36
52.86
Comparative example 3
0.5
0
Comparative example 4
65.32
85.32
From table 6, it can be seen that the titanium silicalite molecular sieve disclosed by the present disclosure has high catalytic activity, and when the titanium silicalite molecular sieve is used in a process for producing ketoxime through a macromolecular ketone ammoximation reaction, the titanium silicalite molecular sieve is favorable for improving the conversion rate of raw materials and the selectivity of a target product, and the utilization rate of hydrogen peroxide is high.
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.
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