CN117466308A - Preparation method of mesoporous-macroporous Ti-MWW molecular sieve - Google Patents

Preparation method of mesoporous-macroporous Ti-MWW molecular sieve Download PDF

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CN117466308A
CN117466308A CN202311408356.4A CN202311408356A CN117466308A CN 117466308 A CN117466308 A CN 117466308A CN 202311408356 A CN202311408356 A CN 202311408356A CN 117466308 A CN117466308 A CN 117466308A
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于浩淼
续晶华
李永果
王贤彬
李进
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China Catalyst Holding Co ltd
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Abstract

The invention provides a preparation method of a mesoporous-macroporous Ti-MWW molecular sieve, which comprises the steps of preparing a silicon source precursor through common modification of a cationic surfactant and polymer microspheres, preparing a boron silicon molecular sieve by taking the silicon source precursor as a silicon source, adding a titanium source into the boron silicon molecular sieve after acid treatment, and finally preparing the mesoporous-macroporous Ti-MWW molecular sieve. The Ti-MWW molecular sieve prepared by the method has better diffusion performance, a macroporous structure and higher titanium active center utilization rate, can effectively reduce the diffusion resistance of a reaction substrate in a pore canal, is beneficial to the contact of a macromolecular reaction substrate and an active site, and has good application prospect in a macromolecular catalytic reaction process.

Description

Preparation method of mesoporous-macroporous Ti-MWW molecular sieve
Technical Field
The invention relates to the technical field of catalyst preparation, in particular to a preparation method of a mesoporous-macroporous Ti-MWW molecular sieve.
Background
In 1983, eniChem, italy, first synthesized a titanium silicalite molecular sieve TS-1 having an isomorphous structure (MFI) with ZSM-5 molecular sieve, which was capable of reacting with hydrogen peroxide (H 2 O 2 ) The method is used for efficiently catalyzing a series of selective oxidation reactions of organic matters under the mild condition of an oxidant, and only water is byproduct, so that the oxidation process is possible to be greenized. The discovery of TS-1 expands the application of the molecular sieve from the field of solid acid catalysis to the field of liquid phase selective catalytic oxidation, and successfully promotes a new process of the catalytic oxidation industry for greening. Following TS-1, more titanium silicalite molecular sieves were synthesized, such as Ti-MCM-41, ti-MOR, ti-Beta, ti-MWW, etc. Because of their different pore channel structures and physicochemical properties, the catalyst has unique advantages in different types of selective oxidation reactions.
The Ti-MWW molecular sieve has the same MWW topological structure as MCM-22, has a unique structure, is derived from a layered precursor, and has the characteristics of plasticity and modifier. The MWW structure derived titanium-silicon molecular sieve with various pore structures can be obtained by a certain technical means. Compared with the traditional Ti-MWW molecular sieve, the pore channels of the Ti-MWW molecular sieve are more open, carbon deposition and pore blocking are less prone to occur, and the titanium active site on the framework is more accessible, so that the application prospect is wider.
For the synthesis of MWW structure titanium silicalite molecular sieve, wu Peng and the like, firstly adopting post-treatment synthesis method (post-synthesis), firstly synthesizing the B-MWW molecular sieve, then washing out most of boron in the molecular sieve through acid washing for multiple times, generating defect sites due to the position vacancies of the boron, then using Piperidine (PI) or HMI as a structure directing agent, adding Ti source for hydrothermal crystallization again, and enabling Ti to enter the defect sites of the crystal lattice, thus forming the Ti-MWW molecular sieve [ Journal of Catalysis, 2004, 228 (1): 183-191]. Fan et al also synthesized a titanium silicalite MWW molecular sieve with a ten-membered ring channel between layers converted into a twelve-membered ring channel by this method, and named Ti-YNU-1[ Journal of Catalysis, 2006, 243 (1): 183-191]. Chinese patent CN102905787B discloses a process for producing titanium-MWW zeolite using a gel formed from a titanium compound, a silicon source, a boron source, an MWW-templating agent and water, with boron as a proppant, by two-step hydrothermal synthesis, followed by an acid treatment of the debrominated and non-framework titanium for the conversion of propylene to propylene oxide. Chinese patent publication No. CN1709574a discloses a method of synthesizing a borotitanium silicalite molecular sieve having MWW structure using F and boron as mineralizers, and then removing boron as an epoxidation catalyst by acid treatment. The titanium-containing MWW structure molecular sieve prepared by the method still belongs to a microporous structure molecular sieve, and the catalytic effect of reactants with larger molecular volumes is not ideal when the titanium-containing MWW structure molecular sieve is applied to the catalytic field.
Disclosure of Invention
In order to solve the defects in the prior art, the mesoporous-macroporous Ti-MWW molecular sieve is prepared by synthesizing the silicon source precursor through the polymer microspheres, so that the diffusion resistance of a reaction substrate in a pore canal is effectively reduced, the contact between the reaction substrate and an active site is facilitated, the reaction substrate has better diffusion performance and higher utilization rate of a titanium active center, the catalytic activity of the reaction substrate in a macromolecular reactant is improved, and the reaction substrate has good application prospect in a process for producing ketoxime by using macromolecular ketoxime reaction.
The technical scheme of the invention is as follows: the preparation method of the mesoporous-macroporous Ti-MWW molecular sieve comprises the following steps:
(1) Preparing a silicon source precursor: uniformly mixing a cationic surfactant and polymer microspheres in an ethanol environment, adding a silicon source, stirring for 2-20 hours at 30-80 ℃, washing, drying and roasting a precipitate to prepare a silicon source precursor;
(2) Preparation of boron-silicon molecular sieve: adding a boron source and a silicon source precursor into the aqueous solution of piperidine, performing hydrothermal crystallization reaction for 4-10 days at 140-180 ℃, washing, drying and roasting the precipitate to obtain a boron-silicon molecular sieve; carrying out acid treatment on the borosilicate molecular sieve to obtain an acid-treated borosilicate molecular sieve;
(3) Preparing a mesoporous-macroporous Ti-MWW molecular sieve: adding an acid-treated boron-silicon molecular sieve and a titanium source into a piperidine aqueous solution, performing hydrothermal crystallization reaction for 4-10 days at 140-180 ℃, and washing, drying and roasting a precipitate to obtain a mesoporous-macroporous Ti-MWW molecular sieve;
in the step (1), the cationic surfactant is a quaternary ammonium salt type cationic surfactant, the silicon source is a silicate compound, the granularity of the polymer microsphere is 80-300 nm, and the mass ratio of the polymer microsphere to the cationic surfactant to the silicon source to the ethanol is 0.05-0.5:0.03-0.2:1.0:1.0-10.0.
In some specific preparation methods, the mass ratio of the polymer microsphere, the cationic surfactant, the silicon source and the ethanol in the step (1) is 0.1-0.5:0.03-0.1:1.0:3.0-10.0.
In some specific preparation methods, the cationic surfactant in the step (1) is at least one of dodecyl trimethyl ammonium chloride, dodecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium chloride, octadecyl trimethyl ammonium bromide and octadecyl trimethyl ammonium chloride.
In some specific preparation methods, the polymer microsphere in the step (1) is at least one of polystyrene microsphere and polymethyl methacrylate microsphere with the granularity of 80-200 nm.
In some specific preparation methods, the silicon source in the step (1) is at least one of tetraethyl silicate, n-butyl silicate and ethyl orthosilicate.
The boron source, the titanium source and the template agent in the preparation method are the boron source, the titanium source and the template agent which are commonly used for synthesizing the Ti-MWW molecular sieve.
Specifically, the boron source is one of boric acid and diboron trioxide.
Specifically, the titanium source is at least one of tetraethyl titanate, tetrapropyl titanate, tetrabutyl titanate, tetraisopropyl titanate and titanium isopropoxide.
The proportion of the raw materials for preparing the borosilicate molecular sieve in the step (2) is the dosage ratio of the conventional synthetic borosilicate molecular sieve.
Some specific synthesis methods, in step (2), the silicon source precursor, according to B 2 O 3 The molar ratio of the boron source to the piperidine to the water is 1.0:0.2-3.0:0.5-4.0:10.0-30.0.
Specific synthesis methods, silicon in step (2)Source precursor, according to B 2 O 3 The molar ratio of the boron source to the piperidine to the water is 1.0:0.2-1.0:0.5-2.0:10.0-30.0.
Some specific synthesis methods, the boron silicon molecular sieve after acid treatment in the step (3) is prepared according to TiO 2 The molar ratio of the titanium source to the piperidine to the water is 1.0:0.01-0.5:0.5-3.5:5.0-35.0.
Some specific synthesis methods, the boron silicon molecular sieve after acid treatment in the step (3) is prepared according to the formula B 2 O 3 The molar ratio of the boron source to the piperidine to the water is 1.0:0.05-0.2:0.5-2.0:5.0-30.0.
The post-treatment step of the synthetic substances in the steps 1-3 adopts a conventional synthetic molecular sieve treatment method.
Specifically, the precipitates in the steps (1), (2) and (3) are respectively washed to be neutral, dried for 10-16 hours at the temperature of 30-100 ℃, and baked for 3-6 hours at the temperature of 450-550 ℃.
The acid treatment step of the borosilicate molecular sieve in the step 2 of the invention is as follows: the obtained borosilicate molecular sieve is treated with 20 to 40 percent HNO 3 And (3) treating the solution for 10-20 hours at the temperature of 60-100 ℃ according to the solid-liquid ratio of 1:5 to obtain the boron-silicon molecular sieve after acid treatment.
Compared with the prior art, the invention has the beneficial technical effects that:
(1) The silicon source precursor prepared by the method has the advantages that a small amount of cationic surfactant is added to enable the surface of the polymer microsphere to be provided with cations, and the negatively charged silicon source can be quickly adsorbed on the surface of the polymer microsphere, so that the dispersibility and the macroporous structure of the final silicon source precursor are ensured;
(2) And introducing a secondary macroporous structure through a silicon source precursor to form the hierarchical mesoporous-macroporous Ti-MWW molecular sieve. The mesoporous-macroporous Ti-MWW molecular sieve prepared by the method of the invention improves the diffusion speed of a macromolecular reaction substrate in a molecular sieve pore canal and improves the catalytic activity of the macromolecular reaction substrate in a macromolecular reactant;
(3) The mesoporous-macroporous Ti-MWW molecular sieve prepared by the method has higher utilization rate of the active center of titanium;
(4) The mesoporous-macroporous Ti-MWW molecular sieve prepared by the method has good application prospect in the process of producing ketoxime by ammoximation of macromolecular ketone.
Drawings
FIG. 1 is an SEM image of a silicon source precursor prepared according to example 1;
FIG. 2 is an SEM image of a mesoporous-macroporous Ti-MWW molecular sieve prepared in example 1.
Detailed Description
In the specific embodiment, the silicon source precursor is prepared by 100% SiO 2 Feeding boric acid with the content of 56.30% of B 2 O 3 Calculating and feeding, namely feeding piperidine according to the calculation of pure substances, and carrying out acid treatment on the boron-silicon molecular sieve according to 100% of SiO 2 Calculated and fed, tetrabutyl titanate contains 11.68 percent of TiO 2 And (5) calculating feeding.
Example 1
The preparation method of the mesoporous-macroporous Ti-MWW molecular sieve comprises the following steps:
(1) Preparing a silicon source precursor: adding 0.5 g dodecyl trimethyl ammonium bromide and 2.5 g polystyrene microspheres with the particle size of 100 nm into 50.0 g ethanol, uniformly mixing, adding 10.0 g tetraethoxysilane under stirring, magnetically stirring at 70 ℃ for 12 h, washing for many times to neutrality, drying at 50 ℃ for 12 h, and roasting at 500 ℃ for 4 h to obtain a silicon source precursor with the particle size of 113 nm;
(2) Preparation of boron-silicon molecular sieve: dissolving 14.85 g piperidine in 66.85g deionized water, adding 10.20g boric acid and 15.07 g silicon source precursor, crystallizing at 170 ℃ for 5 days, washing to neutrality after crystallization, drying at 100 ℃ for 16 h, and roasting at 550 ℃ for 4 h to prepare a borosilicate molecular sieve; 30% HNO with solid-liquid ratio of 1:5 3 Treating the solution at 90 ℃ for 15 h to obtain the boron-silicon molecular sieve after acid treatment;
(3) Preparing a mesoporous-macroporous Ti-MWW molecular sieve: dissolving 29.45 g piperidine in 38.32 g deionized water, adding 25.00 g acid treated borosilicate molecular sieve and 6.88 g tetrabutyl titanate, crystallizing at 150deg.C for 7 days, washing to neutrality after crystallization, oven drying at 100deg.C 16 h, and calcining at 550deg.C 4 h to obtain 1# mesoporous-macroporous Ti-MWW molecular sieve.
Example 2
(1) Preparing a silicon source precursor: adding 0.5 g dodecyl trimethyl ammonium bromide and 2.5 g polymethyl methacrylate balls with the particle size of 100 nm into 50.0 g ethanol, uniformly mixing, adding 10.0 g tetraethoxysilane under stirring, magnetically stirring 12 h at 70 ℃, washing for many times to neutrality, drying at 50 ℃ for 12 h, and roasting at 500 ℃ for 4 h to obtain a silicon source precursor with the particle size of 113 nm;
(2) Preparation of boron-silicon molecular sieve: dissolving 14.85 g piperidine in 66.85g deionized water, adding 10.20g boric acid and 15.07 g silicon source precursor, crystallizing at 170 ℃ for 5 days, washing to neutrality after crystallization, drying at 100 ℃ for 16 h, and roasting at 550 ℃ for 4 h to prepare a borosilicate molecular sieve; 30% HNO with solid-liquid ratio of 1:5 3 Treating the solution at 90 ℃ for 15 h to obtain the boron-silicon molecular sieve after acid treatment;
(3) Preparing a mesoporous-macroporous Ti-MWW molecular sieve: dissolving 29.45 g piperidine in 38.32 g deionized water, adding 25.00 g acid treated borosilicate molecular sieve and 6.88 g tetrabutyl titanate, crystallizing at 150deg.C for 7 days, washing to neutrality after crystallization, oven drying at 100deg.C 16 h, and calcining at 550deg.C 4 h to obtain 2# mesoporous-macroporous Ti-MWW molecular sieve.
Comparing the specific surface area and pore volume of the No. 2 mesoporous-macroporous Ti-MWW molecular sieve sample with those of the No. 1 sample, wherein the specific surface area and pore volume are similar to those of the No. 1 sample.
Example 3
The preparation method of the mesoporous-macroporous Ti-MWW molecular sieve comprises the following steps:
(1) Preparing a silicon source precursor: adding 0.3 g dodecyl trimethyl ammonium bromide and 1.0 g polystyrene microsphere with the particle size of 100 nm into 30.0 g ethanol, uniformly mixing, adding 10.0 g tetraethoxysilane under stirring, magnetically stirring 12 h at 70 ℃, washing for many times to neutrality, drying at 50 ℃ for 12 h, and roasting at 500 ℃ for 4 h to obtain a silicon source precursor with the particle size of 113 nm;
(2) Preparation of boron-silicon molecular sieve: dissolving 14.85 g piperidine in 66.85g deionized water, adding 10.20g boric acid and 15.07 g silicon source precursor, crystallizing at 170deg.C for 5 days, washing to neutrality after crystallization, oven drying at 100deg.C for 16 h, and baking at 550deg.CFiring 4 h to obtain a borosilicate molecular sieve; 30% HNO with solid-liquid ratio of 1:5 3 Treating the solution at 90 ℃ for 15 h to obtain the boron-silicon molecular sieve after acid treatment;
(3) Preparing a mesoporous-macroporous Ti-MWW molecular sieve: dissolving 29.45 g piperidine in 38.32 g deionized water, adding 25.00 g acid treated borosilicate molecular sieve and 6.88 g tetrabutyl titanate, crystallizing at 150deg.C for 7 days, washing to neutrality after crystallization, oven drying at 100deg.C 16 h, and calcining at 550deg.C 4 h to obtain 3# mesoporous-macroporous Ti-MWW molecular sieve.
Example 4
The preparation method of the mesoporous-macroporous Ti-MWW molecular sieve comprises the following steps:
(1) Preparing a silicon source precursor: adding 0.75 g dodecyl trimethyl ammonium bromide and polystyrene microspheres with the particle size of 3.5 g of 100 nm into 70.0 g ethanol, uniformly mixing, adding 10.0 g tetraethoxysilane under stirring, magnetically stirring 12 h at 70 ℃, washing for many times to neutrality, drying at 50 ℃ for 12 h, and roasting at 500 ℃ for 4 h to obtain a silicon source precursor with the particle size of 113 nm;
(2) Preparation of boron-silicon molecular sieve: dissolving 14.85. 14.85 g piperidine in 66.85g deionized water, adding 10.20g boric acid and 15.07 g silicon source precursor, crystallizing at 170 ℃ for 5 days, washing to neutrality after crystallization, drying at 100 ℃ for 16 h, and roasting at 550 ℃ for 4 h to obtain the borosilicate molecular sieve; 30% HNO with solid-liquid ratio of 1:5 3 Treating the solution at 90 ℃ for 15 h to obtain the boron-silicon molecular sieve after acid treatment;
(3) Preparing a mesoporous-macroporous Ti-MWW molecular sieve: dissolving 29.45 g piperidine in 38.32 g deionized water, adding 25.00 g acid treated borosilicate molecular sieve and 6.88 g tetrabutyl titanate, crystallizing at 150deg.C for 7 days, washing to neutrality after crystallization, oven drying at 100deg.C 16 h, and calcining at 550deg.C 4 h to obtain 4# mesoporous-macroporous Ti-MWW molecular sieve.
Example 5
The preparation method of the mesoporous-macroporous Ti-MWW molecular sieve comprises the following steps:
(1) Preparing a silicon source precursor: adding 1.0 g dodecyl trimethyl ammonium bromide and 5.0 g polystyrene microspheres with the particle size of 100 nm into 100.0 g ethanol, uniformly mixing, adding 10.0 g tetraethoxysilane under stirring, magnetically stirring 12 h at 70 ℃, washing for many times to neutrality, drying at 50 ℃ for 12 h, and roasting at 500 ℃ for 4 h to obtain a silicon source precursor with the particle size of 113 nm;
(2) Preparation of boron-silicon molecular sieve: dissolving 14.85 g piperidine in 66.85g deionized water, adding 10.20g boric acid and 15.07 g silicon source precursor, crystallizing at 170 ℃ for 5 days, washing to neutrality after crystallization, drying at 100 ℃ for 16 h, and roasting at 550 ℃ for 4 h to prepare a borosilicate molecular sieve; 30% HNO with solid-liquid ratio of 1:5 3 Treating the solution at 90 ℃ for 15 h to obtain the boron-silicon molecular sieve after acid treatment;
(3) Preparing a mesoporous-macroporous Ti-MWW molecular sieve: dissolving 29.45 g piperidine in 38.32 g deionized water, adding 25.00 g acid treated borosilicate molecular sieve and 6.88 g tetrabutyl titanate, crystallizing at 150deg.C for 7 days, washing to neutrality after crystallization, oven drying at 100deg.C 16 h, and calcining at 550deg.C 4 h to obtain 5# mesoporous-macroporous Ti-MWW molecular sieve.
Example 6
The preparation method of the mesoporous-macroporous Ti-MWW molecular sieve comprises the following steps:
(1) Preparing a silicon source precursor: adding 0.5 g dodecyl trimethyl ammonium bromide and 2.5 g polystyrene microspheres with the particle size of 100 nm into 50.0 g ethanol, uniformly mixing, adding 10.0 g tetraethoxysilane under stirring, magnetically stirring at 70 ℃ for 12 h, washing for many times to neutrality, drying at 50 ℃ for 12 h, and roasting at 500 ℃ for 4 h to obtain a silicon source precursor with the particle size of 113 nm;
(2) Preparation of boron-silicon molecular sieve: dissolving 12.0 g piperidine in 49.12 g deionized water, adding 18.0 g boric acid and 15.07 g silicon source precursor, crystallizing at 170 ℃ for 5 days, washing to neutrality after crystallization, drying at 100 ℃, 16 h, and roasting at 550 ℃ for 4 h to obtain a borosilicate molecular sieve; 30% HNO with solid-liquid ratio of 1:5 3 Treating the solution at 90 ℃ for 15 h to obtain the boron-silicon molecular sieve after acid treatment;
(3) Preparing a mesoporous-macroporous Ti-MWW molecular sieve: dissolving 29.45 g piperidine in 38.32 g deionized water, adding 25.00 g acid treated borosilicate molecular sieve and 6.88 g tetrabutyl titanate, crystallizing at 150deg.C for 7 days, washing to neutrality after crystallization, oven drying at 100deg.C 16 h, and calcining at 550deg.C 4 h to obtain 6# mesoporous-macroporous Ti-MWW molecular sieve.
Example 7
The preparation method of the mesoporous-macroporous Ti-MWW molecular sieve comprises the following steps:
(1) Preparing a silicon source precursor: adding 0.5 g dodecyl trimethyl ammonium bromide and 2.5 g polystyrene microspheres with the particle size of 100 nm into 50.0 g ethanol, uniformly mixing, adding 10.0 g tetraethoxysilane under stirring, magnetically stirring at 70 ℃ for 12 h, washing for many times to neutrality, drying at 50 ℃ for 12 h, and roasting at 500 ℃ for 4 h to obtain a silicon source precursor with the particle size of 113 nm;
(2) Preparation of boron-silicon molecular sieve: dissolving 20.0. 20.0 g piperidine in 78.57 g deionized water, adding 28.3 g boric acid and 15.07 g silicon source precursor, crystallizing at 170 ℃ for 5 days, washing to neutrality after crystallization, drying at 100 ℃, 16 h, and roasting at 550 ℃ for 4 h to obtain a borosilicate molecular sieve; 30% HNO with solid-liquid ratio of 1:5 3 Treating the solution at 90 ℃ for 15 h to obtain the boron-silicon molecular sieve after acid treatment;
(3) Preparing a mesoporous-macroporous Ti-MWW molecular sieve: dissolving 29.45 g piperidine in 38.32 g deionized water, adding 25.00 g acid treated borosilicate molecular sieve and 6.88 g tetrabutyl titanate, crystallizing at 150deg.C for 7 days, washing to neutrality after crystallization, oven drying at 100deg.C 16 h, and calcining at 550deg.C 4 h to obtain 7# mesoporous-macroporous Ti-MWW molecular sieve.
Example 8
The preparation method of the mesoporous-macroporous Ti-MWW molecular sieve comprises the following steps:
(1) Preparing a silicon source precursor: adding 0.5 g dodecyl trimethyl ammonium bromide and 2.5 g polystyrene microspheres with the particle size of 100 nm into 50.0 g ethanol, uniformly mixing, adding 10.0 g tetraethoxysilane under stirring, magnetically stirring at 70 ℃ for 12 h, washing for many times to neutrality, drying at 50 ℃ for 12 h, and roasting at 500 ℃ for 4 h to obtain a silicon source precursor with the particle size of 113 nm;
(2) Preparation of boron-silicon molecular sieve: 30.0. 30.0 g piperidine was dissolved in 97.85Adding 45.0 g boric acid and 15.07 g silicon source precursor into deionized water, crystallizing at 170 ℃ for 5 days, washing to neutrality after crystallization, drying at 100 ℃ for 16 h, and roasting at 550 ℃ for 4 h to obtain a borosilicate molecular sieve; 30% HNO with solid-liquid ratio of 1:5 3 Treating the solution at 90 ℃ for 15 h to obtain the boron-silicon molecular sieve after acid treatment;
(3) Preparing a mesoporous-macroporous Ti-MWW molecular sieve: dissolving 29.45 g piperidine in 38.32 g deionized water, adding 25.00 g acid treated borosilicate molecular sieve and 6.88 g tetrabutyl titanate, crystallizing at 150deg.C for 7 days, washing to neutrality after crystallization, oven drying at 100deg.C 16 h, and calcining at 550deg.C 4 h to obtain 8# mesoporous-macroporous Ti-MWW molecular sieve.
Example 9
The preparation method of the mesoporous-macroporous Ti-MWW molecular sieve comprises the following steps:
(1) Preparing a silicon source precursor: adding 0.5 g dodecyl trimethyl ammonium bromide and 2.5 g polystyrene microspheres with the particle size of 100 nm into 50.0 g ethanol, uniformly mixing, adding 10.0 g tetraethoxysilane under stirring, magnetically stirring at 70 ℃ for 12 h, washing for many times to neutrality, drying at 50 ℃ for 12 h, and roasting at 500 ℃ for 4 h to obtain a silicon source precursor with the particle size of 113 nm;
(2) Preparation of boron-silicon molecular sieve: dissolving 14.85 g piperidine in 66.85g deionized water, adding 10.20g boric acid and 15.07 g silicon source precursor, crystallizing at 170 ℃ for 5 days, washing to neutrality after crystallization, drying at 100 ℃, 16 h, and roasting at 550 ℃ for 4 h to obtain a borosilicate molecular sieve; 30% HNO with solid-liquid ratio of 1:5 3 Treating the solution at 90 ℃ for 15 h to obtain the boron-silicon molecular sieve after acid treatment;
(3) Preparing a mesoporous-macroporous Ti-MWW molecular sieve: dissolving 22.0 g piperidine in 60.0 g deionized water, adding 25.00 g acid treated borosilicate molecular sieve and 14.0 g tetrabutyl titanate, crystallizing at 150deg.C for 7 days, washing to neutrality after crystallization, oven drying at 100deg.C 16 h, and calcining at 550deg.C 4 h to obtain 9# mesoporous-macroporous Ti-MWW molecular sieve.
Example 10
The preparation method of the mesoporous-macroporous Ti-MWW molecular sieve comprises the following steps:
(1) Preparing a silicon source precursor: adding 0.5 g dodecyl trimethyl ammonium bromide and 2.5 g polystyrene microspheres with the particle size of 100 nm into 50.0 g ethanol, uniformly mixing, adding 10.0 g tetraethoxysilane under stirring, magnetically stirring at 70 ℃ for 12 h, washing for many times to neutrality, drying at 50 ℃ for 12 h, and roasting at 500 ℃ for 4 h to obtain a silicon source precursor with the particle size of 113 nm;
(2) Preparation of boron-silicon molecular sieve: dissolving 14.85 g piperidine in 66.85g deionized water, adding 10.20g boric acid and 15.07 g silicon source precursor, crystallizing at 170 ℃ for 5 days, washing to neutrality after crystallization, drying at 100 ℃, 16 h, and roasting at 550 ℃ for 4 h to obtain a borosilicate molecular sieve; 30% HNO with solid-liquid ratio of 1:5 3 Treating the solution at 90 ℃ for 15 h to obtain the boron-silicon molecular sieve after acid treatment;
(3) Preparing a mesoporous-macroporous Ti-MWW molecular sieve: dissolving 50.0 g piperidine in 100.0 g deionized water, adding 25.00 g acid treated borosilicate molecular sieve and 30.0 g tetrabutyl titanate, crystallizing at 150deg.C for 7 days, washing to neutrality after crystallization, oven drying at 100deg.C 16 h, and calcining at 550deg.C 4 h to obtain 10# mesoporous-macroporous Ti-MWW molecular sieve.
Example 11
The preparation method of the mesoporous-macroporous Ti-MWW molecular sieve comprises the following steps:
(1) Preparing a silicon source precursor: adding 0.5 g dodecyl trimethyl ammonium bromide and 2.5 g polystyrene microspheres with the particle size of 100 nm into 50.0 g ethanol, uniformly mixing, adding 10.0 g tetraethoxysilane under stirring, magnetically stirring at 70 ℃ for 12 h, washing for many times to neutrality, drying at 50 ℃ for 12 h, and roasting at 500 ℃ for 4 h to obtain a silicon source precursor with the particle size of 113 nm;
(2) Preparation of boron-silicon molecular sieve: dissolving 14.85 g piperidine in 66.85g deionized water, adding 10.20g boric acid and 15.07 g silicon source precursor, crystallizing at 170 ℃ for 5 days, washing to neutrality after crystallization, drying at 100 ℃, 16 h, and roasting at 550 ℃ for 4 h to obtain a borosilicate molecular sieve; 30% HNO with solid-liquid ratio of 1:5 3 Treating the solution at 90 ℃ for 15 h to obtain the boron-silicon molecular sieve after acid treatment;
(3) Preparing a mesoporous-macroporous Ti-MWW molecular sieve: 70.0 g piperidine is dissolved in 120.0 g deionized water, 25.00 g acid treated borosilicate molecular sieve and 50.0 g tetrabutyl titanate are added, crystallization is carried out for 7 days at 150 ℃, washing is carried out to neutrality after crystallization is finished, drying is carried out at 100 ℃, 16 h is carried out, and roasting is carried out at 550 ℃ for 4 h, thus obtaining the 11# mesoporous-macroporous Ti-MWW molecular sieve.
Comparative example 1
(1) Preparation of boron-silicon molecular sieve: dissolving 14.85 g piperidine in 66.85g deionized water, adding 10.20g boric acid and 15.07 g white carbon black, crystallizing at 170 ℃ for 5 days, washing to neutrality after crystallization, drying at 100 ℃ for 16 h, and roasting at 550 ℃ for 4 h to obtain the borosilicate molecular sieve; 30% HNO with solid-liquid ratio of 1:5 3 Treating the solution at 90 ℃ for 15 h to obtain the boron-silicon molecular sieve after acid treatment;
(2) Preparation of Ti-MWW molecular sieve: dissolving 29.45 g piperidine in 38.32 g deionized water, adding 25.00 g acid treated borosilicate molecular sieve and 6.88 g tetrabutyl titanate, crystallizing at 150deg.C for 7 days, washing to neutrality after crystallization, oven drying at 100deg.C 16 h, and calcining at 550deg.C 4 h to obtain 12# Ti-MWW molecular sieve.
Comparing the specific surface area and pore volume of the 12# Ti-MWW molecular sieve sample and the 1# sample, the specific surface area is much smaller than that of the 1# sample, the mesoporous pore volume is smaller, and the microporous pore volume is larger, so that the 1# sample contains more mesopores and macropore apertures.
The molecular sieves synthesized in the examples and comparative examples were used in catalyzing cyclohexanone ammoximation reactions. The reaction conditions for the ammoximation of cyclohexanone are as follows: 2.5 g of catalyst (mesoporous-macroporous Ti-MWW molecular sieve synthesized in the embodiment), 90 g/h of cyclohexanone and 30 g/h of 50% hydrogen peroxide are added into a four-necked flask, the four-necked flask is placed in an oil bath to ensure that the reaction temperature in the kettle is 75 ℃, then the flow rate of ammonia gas is controlled to be 130 mL/min through a rotor flowmeter, the mixture is stirred and reacted for 6 hours, and after the mixture is cooled to room temperature, a sample in the reaction kettle is taken for chromatographic analysis. (the cyclisation rate of cyclohexanone is the chromatographic conversion and the selectivity of cyclohexanone oxime is the chromatographic selectivity)
The conversion of cyclohexanone is
The selectivity of cyclohexanone oxime is
C 0 : concentration of cyclohexanone before reaction
C 1 : concentration of cyclohexanone after reaction
C Cyclohexanone oxime : concentration of cyclohexanone oxime after reaction
The analytical results of the cyclohexanone ammoximation reaction of the comparative example and the sample of the example are shown in the following table.
Test examples
ASAP 2460 specific surface and pore size Analyzer manufactured by Micromeritics Co., ltd. Through N 2 The adsorption and desorption technique characterizes the specific surface area, pore volume and pore size distribution of the molecular sieves of the examples and the comparative examples. Before the adsorption test, the sample is vacuum activated at 350 ℃ for about 6 h. N at 77K 2 Testing of adsorption and desorption isotherms, calculating specific surface area of sample by BET equation, calculating external specific surface area by t-Plot method (S ext ) And micropore volume (V) micro ) Mesoporous volume (V) is obtained by adopting BJH model calculation method meso ）。
Table 1 examples and comparative examples molecular sieves TiO was synthesized 2 Content, external specific surface area and micropore mesoporous volume data
From the data in Table 1, it can be seen that the addition of the surfactant and the polymer microspheres can effectively increase the external specific surface area and the mesoporous volume of the Ti-MWW molecular sieve, and simultaneously reduce the microporous volume, and thus the mesoporous-macroporous Ti-MWW molecular sieve is synthesized by the method of the invention. In addition, tiO in the product molecular sieve 2 The content of (2) is mainly determined by the adding amount of the titanium source in the mesoporous-macroporous Ti-MWW molecular sieve in the step 3.
Table 2 catalytic activity in cyclohexanone ammoximation reactions of examples and comparative examples
From the data in Table 2, it is clear that the Ti-MWW molecular sieve added with the surfactant and the polymer microsphere can obviously improve the conversion rate of cyclohexanone and the selectivity of cyclohexanone oxime in the process of catalyzing the ammoximation reaction of cyclohexanone.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.

Claims (10)

1. The preparation method of the mesoporous-macroporous Ti-MWW molecular sieve is characterized by comprising the following steps of:
(1) Preparing a silicon source precursor: uniformly mixing a cationic surfactant and polymer microspheres in an ethanol environment, adding a silicon source, stirring for 2-20 hours at 30-80 ℃, washing, drying and roasting a precipitate to prepare a silicon source precursor;
(2) Preparation of boron-silicon molecular sieve: adding a boron source and a silicon source precursor into the aqueous solution of piperidine, performing hydrothermal crystallization reaction for 4-10 days at 140-180 ℃, washing, drying and roasting the precipitate to obtain a boron-silicon molecular sieve; carrying out acid treatment on the borosilicate molecular sieve to obtain an acid-treated borosilicate molecular sieve;
(3) Preparing a mesoporous-macroporous Ti-MWW molecular sieve: adding an acid-treated boron-silicon molecular sieve and a titanium source into a piperidine aqueous solution, performing hydrothermal crystallization reaction for 4-10 days at 140-180 ℃, and washing, drying and roasting a precipitate to obtain a mesoporous-macroporous Ti-MWW molecular sieve;
in the step (1), the cationic surfactant is a quaternary ammonium salt type cationic surfactant, the silicon source is a silicate compound, the granularity of the polymer microsphere is 80-300 nm, and the mass ratio of the polymer microsphere to the cationic surfactant to the silicon source to the ethanol is 0.05-0.5:0.03-0.2:1.0:1.0-10.0.
2. The preparation method of the mesoporous-macroporous Ti-MWW molecular sieve according to claim 1, wherein the mass ratio of the polymer microsphere to the cationic surfactant to the silicon source to the ethanol in the step (1) is 0.1-0.5:0.03-0.1:1.0:3.0-10.0.
3. The method for preparing a mesoporous-macroporous Ti-MWW molecular sieve according to claim 1, wherein the cationic surfactant in step (1) is at least one of dodecyl trimethyl ammonium chloride, dodecyl trimethyl ammonium bromide, cetyl trimethyl ammonium chloride, octadecyl trimethyl ammonium bromide, and octadecyl trimethyl ammonium chloride.
4. The method for preparing a mesoporous-macroporous Ti-MWW molecular sieve according to claim 1, wherein the polymer microsphere in the step (1) is at least one of polystyrene microsphere and polymethyl methacrylate microsphere with the granularity of 80-200 nm.
5. The method for preparing a mesoporous-macroporous Ti-MWW molecular sieve according to any one of claims 1 to 4, wherein the silicon source in step (1) is at least one of tetraethyl silicate, n-butyl silicate, and ethyl orthosilicate.
6. The method for preparing a mesoporous-macroporous Ti-MWW molecular sieve according to any one of claims 1 to 4, wherein the boron source in the step (2) is one of boric acid and diboron trioxide.
7. The method for preparing a mesoporous-macroporous Ti-MWW molecular sieve according to any one of claims 1 to 4, wherein the precursor of the silicon source in the step (2) is a compound according to B 2 O 3 The molar ratio of the boron source to the piperidine to the water is 1.0:0.2-3.0:0.5-4.0:10.0-30.0.
8. The method for preparing a mesoporous-macroporous Ti-MWW molecular sieve according to any one of claims 1 to 4, wherein the titanium source in the step (3) is at least one of tetraethyl titanate, tetrapropyl titanate, tetrabutyl titanate, tetraisopropyl titanate, and titanium isopropoxide.
9. The method for preparing a mesoporous-macroporous Ti-MWW molecular sieve according to any one of claims 1 to 4, wherein the acid-treated borosilicate molecular sieve in the step (3) is a TiO-based molecular sieve 2 The molar ratio of the titanium source to the piperidine to the water is 1.0:0.01-0.5:0.5-3.5:5.0-35.0.
10. The method for preparing a mesoporous-macroporous Ti-MWW molecular sieve according to any one of claims 1 to 4, wherein the precipitates in the steps (1), (2) and (3) are respectively washed to be neutral, dried at 30 to 100 ℃ for 10 to 16 hours, and baked at 450 to 550 ℃ for 3 to 6 hours.
CN202311408356.4A 2023-10-27 2023-10-27 Preparation method of mesoporous-macroporous Ti-MWW molecular sieve Pending CN117466308A (en)

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