A preparation method of an olefin epoxidation TS-1 molecular sieve

Abstract

The present application relates to the technical field of catalyst, in particular to a preparation method of TS-1 molecular sieve for olefin epoxidation; the main preparation method is as follows: tetraethyl orthosilicate is added dropwise into an aqueous solution containing tetrapropylammonium hydroxide; after the solution is clarified, a solution containing tetrabutyl titanate and isopropanol is added dropwise; after hydrolysis is completed, guanidine acetate is added; the precursor solution is obtained after stirring at a certain temperature for a period of time; the obtained solution is loaded into a kettle, and the crystallization product is obtained after hydrothermal crystallization; finally, the sheet-shaped TS-1 molecular sieve is obtained through centrifugation, drying and calcination; the present application has low cost, simple operation, short synthesis period, small size in the b-axis direction, improved diffusion mass transfer rate, and good catalytic activity in 1-hexene epoxidation, cyclohexene epoxidation, propylene epoxidation, chloropropylene epoxidation and phenol hydroxylation reaction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalyst, in particular to a preparation method of TS-1 molecular sieve for olefin epoxidation. BACKGROUND

[0002] Epoxides are important chemical synthesis intermediates, and are important raw materials for producing fine chemicals, food additives and pharmaceutical intermediates. The charge polarization of the epoxide group and the tension existing in the ring determine that epoxides have high reactivity, are easy to undergo ring-opening reaction and are converted into a series of valuable chemical products such as surfactants, polymers, ethylene glycol, etc.

[0003] The catalytic oxidation system composed of TS-1 molecular sieve and H2O2 is widely used in important processes such as olefin epoxidation, cyclohexanone ammoxidation, phenol hydroxylation, etc. due to its mild reaction conditions, strong operability, green environmental protection and other characteristics.

[0004] Chinese patent CN116081635A: relates to the technical field of catalyst, discloses a thin sheet TS-1 molecular sieve and its preparation method and application. The thin sheet TS-1 molecular sieve has MFI topological structure, the b-axis is shorter than the a-axis and the c-axis, and the thickness of the thin sheet TS-1 molecular sieve is 50-100 nm. Because the thin sheet TS-1 molecular sieve has a small size in the b-axis direction, the diffusion path of the product in the zeolite is shortened to a certain extent, and the steric hindrance of the zeolite is weakened, so that it has excellent catalytic activity. At the same time, the thin sheet TS-1 molecular sieve prepared by the preparation method of the present application has excellent catalytic activity and high selectivity for epoxy alkane when used for catalyzing high-carbon alpha-olefins.

[0005] Chinese patent CN112408414B: provides a preparation method of a high-stability and high-activity nanosheet-type hierarchical pore core-shell structure TS-1 molecular sieve catalyst and its application. The core layer of the TS-1 catalyst is a nanosheet-type hierarchical pore TS-1 molecular sieve, and the shell layer of the catalyst is a pure silica molecular sieve Silicalite-1. Through the construction of the hierarchical pore TS-1 nanosheet-type molecular sieve catalyst, the internal diffusion limitation problem existing in the pore of the traditional granular titanium silicate molecular sieve can be eliminated, and the surface acidity of the conventional TS-1 molecular sieve can be reduced by constructing a pure silica molecular sieve Silicalite-1 shell layer on the surface to inhibit the generation of ring-opening by-products. The catalyst can be applied to the reaction of synthesizing epoxide chloropropane by chloropropylene hydrogen peroxide method, and can effectively improve the selectivity of epoxide chloropropane and the service life of the catalyst.

[0006] Chinese patent CN103553068B: provides a low-cost, low-pollution, can be in a wide range of change TS-1 molecular sieve silicon titanium ratio (30-150) method, the method is: step one, preparation of seed crystal; Step two, preparation of template-free mixed gel; Step three, the seed crystal prepared in step one is added to the gel in step two for crystallization, after cooling, centrifugal filtration, washing, drying, calcination, TS-1 molecular sieve is obtained. The method provided in the application uses a small amount of template in the process of synthesizing seed crystal, compared with other methods for synthesizing TS-1 molecular sieve, the amount of template is only 1 / 20-1 / 50 of other methods, the problems of high production cost of molecular sieve and environmental pollution caused by high price and high toxicity of organic template are solved. SUMMARY

[0007] In order to solve the above problems, the application provides a preparation method of TS-1 molecular sieve for olefin epoxidation, the operation steps of which are as follows:

[0008] A1: tetraethyl orthosilicate is added dropwise into an aqueous solution containing tetrapropylammonium hydroxide;

[0009] A2: after the solution is clarified, a solution of 0.2-0.4 parts of tetrabutyl titanate and 1.0-2.0 parts of isopropanol is added dropwise;

[0010] A3: after hydrolysis is completed, 0.5-1.0 parts of guanidino compound is added;

[0011] A4: after the temperature is raised and stirring, a precursor solution is obtained after the reaction is completed;

[0012] A5: the obtained solution is loaded into a kettle, and a crystallization product is obtained after hydrothermal crystallization, and finally centrifugation, drying and calcination are carried out to obtain TS-1 molecular sieve for olefin epoxidation.

[0013] In A1, the molar ratio of tetrapropylammonium hydroxide with a concentration of 25% and tetraethyl orthosilicate calculated in terms of SiO2 is 0.1-0.5:1, and the molar ratio of deionized water and tetraethyl orthosilicate is 20-50:1.

[0014] The reaction temperature of A4 is 70-90°C, and the time is 6-24h.

[0015] The hydrothermal crystallization temperature of A5 is 100-200°C, and the time is 24-72h.

[0016] The calcination temperature of A5 is 500-600°C, and the time is 2-8h.

[0017] The preparation method of the guanidino compound is as follows:

[0018] B1: according to mass fraction, 2-5 parts of titanium tetrachloride, 13-26 parts of 3-(2-carboxyvinyl) phenylboric acid, 120-200 parts of ethanol are added into a closed stirring kettle, and stirred at 30-40 DEG C for 30-60 min;

[0019] B2: according to mass fraction, 0.002-0.2 parts of 3-(2-carboxyvinyl) phenylboric acid titanium complex, 30-60 parts of 1,1'-bis(dimethylsilyl) iron, 13-26 parts of vinyl guanidine amine are added into a reaction kettle, heated to 70-80 DEG C under nitrogen protection, then 0.03-0.07 parts of Kast catalyst CAS: 68478-92-2 are added into the reaction kettle, temperature control reaction is carried out for 40-80 min, methanol is removed by distillation, and guanidino compound is obtained.

[0020] The operation steps of the 1-hexene epoxidation reaction catalyzed by the TS-1 molecular sieve are as follows:

[0021] C1: the flaky TS-1, 1-hexene, methanol are mixed uniformly in a round-bottom flask; wherein the mass ratio of flaky TS-1 to 1-hexene is 1:10-20, and the mass ratio of 1-hexene to methanol is 1:5-10;

[0022] C2: the round-bottom flask is placed in a water bath and stirred until a certain temperature is reached, and hydrogen peroxide is added to start the reaction; wherein the mass ratio of 1-hexene to hydrogen peroxide is 1:1-3;

[0023] C3: after the reaction is completed, cold water bath is used for rapid cooling to room temperature.

[0024] The reaction temperature of C2 is 50-80 DEG C, the normal pressure, the rotation speed is 500-1000 rpm, and the reaction time is 2-4 h.

[0025] Catalyst preparation reaction mechanism

[0026] 3-(2-carboxyvinyl) phenylboric acid titanium complex, 1,1'-bis(dimethylsilyl) iron, vinyl guanidine amine occur silicon hydrogen addition reaction, obtain the guanidino compound containing boron acid titanium complex, ferrocene, guanidino.

[0027] Technical effects:

[0028] Compared with the prior art, the preparation method of the TS-1 molecular sieve for olefin epoxidation has the following remarkable effects:

[0029] 1、The scanning electron microscope graph of the flaky TS-1 prepared by the present application shows that the prepared material is indeed flaky, and the b-axis size is about 70 nm, and the c-axis length is about 1 mu m;

[0030] 2. The XRD pattern of the sheet-like TS-1 prepared by this invention shows that the material has typical MFI structural characteristic peaks, and the modified material retains the original crystal form and relative crystallinity.

[0031] 3. The UV-vis spectrum of the sheet-like TS-1 prepared by this invention shows that the sample has both tetracoordinated titanium and a certain amount of hexacoordinated titanium, and contains a small amount of anatase TiO2.

[0032] 4. The TS-1 molecular sieve for olefin epoxidation prepared by this invention is low in cost, simple to operate, and has a short synthesis cycle. Its size is reduced in the b-axis direction, which improves the diffusion mass transfer rate. It has good catalytic activity in the epoxidation of 1-hexene, cyclohexene, propylene, chloropropylene, and phenol hydroxylation reactions. Attached Figure Description

[0033] Figure 1 A scanning electron microscope image of the sheet-like TS-1 prepared in Example 1;

[0034] Figure 2 The XRD pattern of the sheet-like TS-1 prepared in Example 1;

[0035] Figure 3 The UV-vis spectrum of the sheet-like TS-1 prepared in Example 1. Detailed Implementation

[0036] The invention will be further illustrated below through specific embodiments:

[0037] 0.40 g of ethylbenzene was added to the reaction solution as an internal standard. After mixing thoroughly, a small amount of the reaction solution was centrifuged, and the supernatant was then subjected to GC analysis to calculate the conversion rate and selectivity of each product.

[0038] Example 1

[0039] A method for preparing TS-1 molecular sieves for olefin epoxidation, comprising the following steps:

[0040] A1: Add tetraethyl orthosilicate dropwise to an aqueous solution containing tetrapropylammonium hydroxide;

[0041] A2: After the above solution becomes clear, add a solution of 0.2g tetrabutyl titanate and 1.0g isopropanol dropwise.

[0042] A3: After hydrolysis is complete, add 0.5g of guanidine compound;

[0043] A4: Heat and stir. After the reaction is complete, a precursor solution is obtained.

[0044] A5: The obtained solution is loaded into a tank, and a crystallization product is obtained after hydrothermal crystallization, and finally centrifuged, dried, calcined to obtain a TS-1 molecular sieve for olefin epoxidation.

[0045] The molar ratio of the amount of tetrapropylammonium hydroxide with a concentration of 25% in A1 to tetraethyl orthosilicate calculated in terms of SiO2 is 0.1:1, and the molar ratio of the amount of deionized water to tetraethyl orthosilicate is 20:1.

[0046] The reaction temperature of A4 is 70°C, and the time is 6h.

[0047] The hydrothermal crystallization temperature of A5 is 100°C, and the time is 24h.

[0048] The calcination temperature of A5 is 500°C, and the time is 2h.

[0049] The preparation method of the guanidino compound is:

[0050] B1: 2g of titanium tetrachloride, 13g of 3-(2-carboxyvinyl) phenylboronic acid, 120g of ethanol, are added to a sealed stirred tank, and stirred at 30°C for 30min;

[0051] B2: 0.002g of 3-(2-carboxyvinyl) phenylboronic acid titanium complex, 30g of 1,1'-bis(dimethylsilyl) iron, 13g of vinyl guanidine, are added to the reaction kettle, heated to 70°C under nitrogen protection, then 0.03g of Kast catalyst CAS: 68478-92-2 is added to the reaction kettle, and temperature control reaction is carried out for 40min, and methanol is removed by distillation to obtain a guanidino compound.

[0052] The operation steps of the 1-hexene epoxidation reaction catalyzed by the TS-1 molecular sieve are as follows:

[0053] C1: The flaky TS-1, 1-hexene, methanol are mixed uniformly in a round-bottom flask; wherein the mass ratio of flaky TS-1 to 1-hexene is 1:10, and the mass ratio of 1-hexene to methanol is 1:5;

[0054] C2: The round-bottom flask is placed in a water bath for stirring until a certain temperature is reached, and hydrogen peroxide is added to start the reaction; wherein the mass ratio of 1-hexene to hydrogen peroxide is 1:1

[0055] C3: After the reaction is completed, cold water bath is used for rapid cooling to room temperature.

[0056] The reaction temperature of C2 is 50°C, the normal pressure, the rotation speed is 500rpm, and the reaction time is 2h.

[0057] Example 2

[0058] A method for preparing TS-1 molecular sieve for olefin epoxidation, the operation steps are:

[0059] A1: tetraethyl orthosilicate is added dropwise into an aqueous solution containing tetrapropylammonium hydroxide;

[0060] A2: after the solution is clarified, a solution of 0.3 g of tetrabutyl titanate and 1.3 g of isopropyl alcohol is added dropwise;

[0061] A3: after hydrolysis is completed, 0.6 g of guanidino compound is added;

[0062] A4: after warming and stirring, a precursor solution is obtained after the reaction is completed;

[0063] A5: the obtained solution is loaded into a kettle, and a crystallization product is obtained after hydrothermal crystallization, and finally, centrifugation, drying, and calcination are performed to obtain TS-1 molecular sieve for olefin epoxidation.

[0064] In A1, the molar ratio of the concentration of 25% tetrapropylammonium hydroxide and the amount of tetraethyl orthosilicate calculated in terms of SiO2 is 0.2:1, and the molar ratio of the amount of deionized water and tetraethyl orthosilicate is 30:1.

[0065] The reaction temperature of A4 is 75℃, and the time is 12h.

[0066] The hydrothermal crystallization temperature of A5 is 140℃, and the time is 48h.

[0067] The calcination temperature of A5 is 530℃, and the time is 4h.

[0068] The preparation method of the guanidino compound is:

[0069] B1: 3 g of titanium tetrachloride, 18 g of 3-(2-carboxyvinyl) phenylboronic acid, and 140 g of ethanol are added into a sealed stirring kettle, and stirred at 35℃ for 40 min;

[0070] B2: 0.1 g of 3-(2-carboxyvinyl) phenylboronic acid titanium complex, 40 g of 1,1'-bis(dimethylsilyl) iron, and 18 g of vinyl guanidine are added into a reaction kettle, heated to 75℃ under nitrogen protection, then 0.04 g of Kast catalyst CAS: 68478-92-2 is added into the reaction kettle, and temperature control reaction is performed for 50 min, and methanol is removed by distillation to obtain the guanidino compound.

[0071] The operation steps of using TS-1 molecular sieve to catalyze 1-hexene epoxidation reaction are:

[0072] C1: mixing the flaky TS-1, 1-hexene, methanol, and a round bottom flask in a uniform manner; wherein the mass ratio of the flaky TS-1 to 1-hexene is 1:13, and the mass ratio of 1-hexene to methanol is 1:6;

[0073] C2: placing the round bottom flask in a water bath and stirring until reaching a certain temperature, and then adding hydrogen peroxide to start the reaction; wherein the mass ratio of 1-hexene to hydrogen peroxide is 1:2;

[0074] C3: after the reaction is completed, rapidly cooling to room temperature in a cold water bath.

[0075] The reaction temperature of C2 is 60℃, the normal pressure, the rotation speed is 600rpm, and the reaction time is 3h.

[0076] Example 3

[0077] A preparation method of TS-1 molecular sieve for olefin epoxidation, the operation steps of which are as follows:

[0078] A1: adding tetraethyl orthosilicate dropwise into an aqueous solution containing tetrapropylammonium hydroxide;

[0079] A2: after the solution is clarified, adding a solution of 0.3g tetrabutyl titanate and 1.8g isopropyl alcohol dropwise;

[0080] A3: after the hydrolysis is completed, adding 0.8g guanidino compound;

[0081] A4: increasing the temperature and stirring, and after the reaction is completed, obtaining a precursor solution;

[0082] A5: loading the obtained solution into a kettle, obtaining a crystallization product after hydrothermal crystallization, and finally centrifuging, drying, and calcining to obtain TS-1 molecular sieve for olefin epoxidation.

[0083] In A1, the molar ratio of the use amount of 25% tetrapropylammonium hydroxide and tetraethyl orthosilicate calculated in terms of SiO2 is 0.4:1, and the molar ratio of the use amount of deionized water and tetraethyl orthosilicate is 40:1.

[0084] The reaction temperature of A4 is 85℃, and the time is 20h.

[0085] The hydrothermal crystallization temperature of A5 is 180℃, and the time is 60h.

[0086] The calcination temperature of A5 is 580℃, and the time is 6h.

[0087] The preparation method of the guanidino compound is as follows:

[0088] B1: 4g titanium tetrachloride, 22g 3-(2-carboxyvinyl) phenylboric acid, 180g ethanol, were added to a closed stirred tank, stirred at 35℃ for 50min;

[0089] B2: 0.15g of 3-(2-carboxyvinyl) phenylboric acid titanium complex, 50g of 1,1'-bis(dimethylsilyl) iron, 22g of vinyl guanidine amine, were added to the reaction kettle, heated to 75℃ under nitrogen protection, then 0.06g of Kast catalyst CAS: 68478-92-2 was added to the reaction kettle, temperature control reaction for 70min, distillation to remove methanol, to obtain guanidine compound.

[0090] The operation steps of the TS-1 molecular sieve catalyzed 1-hexene epoxidation reaction are as follows:

[0091] C1: The flaky TS-1, 1-hexene, methanol were mixed uniformly in a round-bottom flask; wherein the mass ratio of flaky TS-1 to 1-hexene was 1:18, and the mass ratio of 1-hexene to methanol was 1:9;

[0092] C2: The round-bottom flask was placed in a water bath for stirring until a certain temperature was reached, and hydrogen peroxide was added to start the reaction; wherein the mass ratio of 1-hexene to hydrogen peroxide was 1:2;

[0093] C3: After the reaction was completed, the cold water bath was rapidly cooled to room temperature.

[0094] The reaction temperature of C2 was 70℃, the normal pressure, the rotation speed was 900rpm, and the reaction time was 3h.

[0095] Example 4

[0096] A preparation method of TS-1 molecular sieve for olefin epoxidation, the operation steps are as follows:

[0097] A1: Tetraethyl orthosilicate was added dropwise to an aqueous solution containing tetrapropylammonium hydroxide;

[0098] A2: After the above solution was clarified, a solution of 0.4g tetrabutyl titanate and 2.0g isopropanol was added dropwise;

[0099] A3: After hydrolysis was completed, 1.0g guanidine compound was added;

[0100] A4: After warming and stirring, a precursor solution was obtained after the reaction was completed;

[0101] A5: The obtained solution was loaded into a kettle, and a crystallization product was obtained after hydrothermal crystallization, followed by centrifugation, drying, and calcination to obtain TS-1 molecular sieve for olefin epoxidation.

[0102] The molar ratio of the amount of tetrapropylammonium hydroxide with a concentration of 25% in A1 and tetraethyl orthosilicate calculated in terms of SiO2 is 0.5:1, and the molar ratio of the amount of deionized water and tetraethyl orthosilicate is 50:1.

[0103] The reaction temperature of A4 is 90°C, and the time is 24h.

[0104] The hydrothermal crystallization temperature of A5 is 200°C, and the time is 72h.

[0105] The calcination temperature of A5 is 600°C, and the time is 8h.

[0106] The preparation method of the guanidino compound is:

[0107] B1: 5g of titanium tetrachloride, 26g of 3-(2-carboxyvinyl) phenylboronic acid, 200g of ethanol are added to a sealed stirred tank, stirred at 40°C for 60min;

[0108] B2: 0.2g of 3-(2-carboxyvinyl) phenylboronic acid titanium complex, 60g of 1,1'-bis(dimethylsilyl) iron, 26g of vinyl guanidine, are added to the reaction kettle, heated to 80°C under nitrogen protection, then 0.07g of Kast catalyst CAS: 68478-92-2 is added to the reaction kettle, temperature control reaction for 80min, distillation to remove methanol, to obtain a guanidino compound.

[0109] The operation steps of the 1-hexene epoxidation reaction catalyzed by TS-1 molecular sieve are:

[0110] C1: The flaky TS-1, 1-hexene, methanol are mixed uniformly in a round-bottom flask; wherein the mass ratio of flaky TS-1 to 1-hexene is 1:20, and the mass ratio of 1-hexene to methanol is 1:10;

[0111] C2: The round-bottom flask is placed in a water bath for stirring until a certain temperature is reached, and hydrogen peroxide is added to start the reaction; wherein the mass ratio of 1-hexene to hydrogen peroxide is 1:3;

[0112] C3: After the reaction is completed, cold water bath is used for rapid cooling to room temperature.

[0113] The reaction temperature of C2 is 80°C, normal pressure, the rotation speed is 1000rpm, and the reaction time is 4h.

[0114] Comparative Example 1

[0115] Without adding a guanidino compound, the others are the same as Example 1.

[0116] Comparative Example 2

[0117] Without adding 3-(2-carboxyvinyl)benzene boronic acid, other same as example 1.

[0118] Comparative example 3

[0119] Without adding 1,1'-bis(dimethylsilyl) iron, other same as example 1.

[0120]

[0121]

[0122] Through the data analysis of the above examples and comparative examples, the 1-hexene conversion rate and the cyclohexene oxide selectivity of the TS-1 molecular sieve of the present application are both higher than those of the prior art, which is due to the fact that the b axis of the flaky TS-1 is shortened, the mass transfer rate of the substrate is improved, the TS-1 of the present application contains six-coordinated titanium which also has good catalytic performance for the 1-hexene epoxidation reaction, and the anatase content is very small.

Claims

1. A method for preparing TS-1 molecular sieve for olefin epoxidation, the operating steps of which are as follows: A1: tetraethyl orthosilicate is added dropwise to an aqueous solution containing tetrapropylammonium hydroxide; A2: after the solution is clarified, a solution of 0.2-0.4 parts of tetrabutyl titanate and 1.0-2.0 parts of isopropanol is added dropwise; A3: after hydrolysis is completed, 0.5-1.0 parts of a guanidino compound is added; A4: after the temperature is raised and stirring is performed, a precursor solution is obtained after the reaction is completed; A5: the obtained solution is loaded into a tank, and a crystallization product is obtained after hydrothermal crystallization, followed by centrifugation, drying, and calcination to obtain TS-1 molecular sieve for olefin epoxidation; The preparation method of the guanidino compound is as follows: B1: according to mass fraction, 2-5 parts of titanium tetrachloride, 13-26 parts of 3-(2-carboxyvinyl)phenylboronic acid, and 120-200 parts of ethanol are added to a sealed stirring tank, and stirring is performed at 30-40℃ for 30-60 min; B2: according to mass fraction, 0.002-0.2 parts of a titanium complex of 3-(2-carboxyvinyl)phenylboronic acid, 30-60 parts of 1,1'-bis(dimethylsilyl)ferrocene, and 13-26 parts of vinyl guanidine are added to a reaction tank, heating is performed to 70-80℃ under nitrogen protection, then 0.03-0.07 parts of Kast catalyst CAS: 68478-92-2 is added to the reaction tank, temperature-controlled reaction is performed for 40-80 min, and methanol is removed by distillation to obtain the guanidino compound.

2. The method for preparing TS-1 molecular sieve for olefin epoxidation according to claim 1, characterized in that: In A1, the concentration of tetrapropylammonium hydroxide is 25%, and the molar ratio of the amount of tetraethyl orthosilicate to SiO2 is 0.1-0.5:1, and the molar ratio of the amount of deionized water to tetraethyl orthosilicate is 20-50:

1.

3. The method for preparing TS-1 molecular sieve for olefin epoxidation according to claim 1, characterized in that: The reaction temperature of A4 is 70-90℃, and the time is 6-24 h.

4. The method for preparing TS-1 molecular sieve for olefin epoxidation according to claim 1, characterized in that: The hydrothermal crystallization temperature of A5 is 100-200℃, and the time is 24-72 h.

5. The method for preparing TS-1 molecular sieve for olefin epoxidation according to claim 1, characterized in that: The calcination temperature of A5 is 500-600℃, and the time is 2-8 h.

6. The method for preparing TS-1 molecular sieve for olefin epoxidation according to claim 1, characterized in that: Specifically, TS-1 molecular sieve is used to catalyze 1-hexene epoxidation, and the operating steps are as follows: C1: flaky TS-1, 1-hexene, and methanol are uniformly mixed in a round-bottom flask; wherein the mass ratio of flaky TS-1 to 1-hexene is 1:10-20, and the mass ratio of 1-hexene to methanol is 1:5-10; C2: the round-bottom flask is placed in a water bath for stirring until the reaction temperature is reached, and hydrogen peroxide is added to start the reaction; wherein the mass ratio of 1-hexene to hydrogen peroxide is 1:1-3; C3: after the reaction is completed, cold water bath quenching is performed to room temperature.

7. The method for preparing TS-1 molecular sieve for olefin epoxidation according to claim 6, characterized in that: The reaction temperature of C2 is 50-80℃, the pressure is normal, the rotation speed is 500-1000 rpm, and the reaction time is 2-4 h.

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