System and process for synthesizing molecular sieve through continuous crystallization
Through continuous flow reaction in the reaction tube through continuous crystallization synthesis method, the problem of insufficient pore structure and specific surface area of titanium silicon molecular sieve is solved, and the preparation of titanium silicon molecular sieve with small particle size and rich pore structure is realized, which improves catalytic performance and reduces process complexity and cost.
Patent Information
- Application Number
- CN202411744008.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-30
- Publication Date
- 2025-03-07
AI Technical Summary
The internal pore structure and specific surface area of the existing titanium silicon molecular sieve are insufficient, the preparation process is complex and costly, and there is no synthesis process to achieve continuous flowable hydrothermal reaction.
The continuous crystallization synthesis method is used to continuously flow the aqueous solution of alkyl orthosilicate and tetrapropyl ammonium hydroxide in the reaction tube, and the ethanol solution of tetraalkyl titanate is added. After temperature control and additive adjustment, a continuous flow reaction is achieved at 130~180 °C, and a titanium silicon molecular sieve with small particle size and rich pore structure is obtained.
The preparation of titanium silicon molecular sieve with small particle size and uniform distribution is realized, which improves catalytic performance and reduces process complexity and cost. At the same time, the synthesis process of continuous flowable hydrothermal reaction is realized for the first time.
Smart Images
Figure CN119569072A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a system and process for continuous crystallization synthesis of molecular sieves, belonging to the technical field of titanium silicon molecular sieve catalyst synthesis. Background Art
[0002] Titanium silicate molecular sieve is an important environmentally friendly catalyst. Its catalytic system with hydrogen peroxide can efficiently catalyze many important reactions such as olefin epoxidation, aromatic hydroxylation, aldehyde ketone ammoximation, alkane oxidation, etc. In recent years, with the development of related chemical industries and technological progress, not only the traditional titanium silicate molecular sieve market has shown a steady growth trend. The demand for new porous titanium silicate molecular sieves with high activity, rich internal pore structure, large specific surface area and small particle size is also growing rapidly.
[0003] Titanium silicon molecular sieve uses titanium as the active center. During the synthesis of titanium silicon molecular sieve, transition metal titanium atoms are introduced into the framework of the molecular sieve to replace some silicon atoms in the silicon-oxygen tetrahedron, resulting in a type of heteroatom molecular sieve. At present, titanium silicon molecular sieve is prepared by adding silicon source, titanium source and template agent into an intermittent reactor through hydrothermal synthesis. In order to improve the internal pore structure and specific surface area of titanium silicon molecular sieve, scholars in the industry have successively studied hard template method, soft template method and post-processing synthesis methods. The operation process of these methods is relatively complex, cumbersome and costly. In addition, in the preparation of titanium silicon molecular sieve and other molecular sieve technology fields, it is generally recognized that the hydrothermal crystallization reaction needs to be completed in a crystallization reactor. So far, there has been no synthesis process that completes the hydrothermal reaction in a pipeline through continuous flow. Summary of the invention
[0004] In order to improve the pore structure of the rich titanium silicate molecular sieve catalyst, reduce the particle diameter of the titanium silicate molecular sieve, and thus improve the catalytic performance of the titanium silicate catalyst, the present invention provides a method for preparing a small particle size titanium silicate molecular sieve catalyst.
[0005] The technical solution of the present invention is a method for continuously crystallizing and synthesizing titanium silicon molecular sieve, which adopts the following steps: adding an aqueous solution of alkyl orthosilicate and tetrapropylammonium hydroxide for preparing titanium silicon molecular sieve into a reaction tube, continuously flowing in the reaction tube at 0-30°C, adding an ethanol solution of tetraalkyl titanate to the reaction tube after flowing for 10 min-40 min, continuing to flow continuously at 0-30°C for 10 min-40 min, and continuously flowing and reacting at 130-180°C in the reaction tube for 10-50 h, cooling to room temperature, filtering, washing, drying and calcining to obtain the titanium silicon molecular sieve.
[0006] Some specific methods for synthesizing titanium silicalite molecular sieves are characterized in that an auxiliary agent is added at least once during continuous flow at 130-180°C for 1-9 hours.
[0007] The auxiliary agent is polyacrylamide, and the mass ratio of alkyl orthosilicate to the auxiliary agent is 1:0.01-0.08 based on silicon dioxide.
[0008] Some specific methods for synthesizing titanium silicalite molecular sieves include adding additives to the reaction tube after continuous flow at 130-180 °C for 1-2 hours, 3-5 hours, and 6-9 hours; The mass ratio of alkyl orthosilicate to the additive is 1:0.02~0.05 based on silicon dioxide.
[0009] Some specific methods for synthesizing titanium silicate molecular sieves are as follows: tetraalkyl titanate is calculated as titanium dioxide, alkyl orthosilicate is calculated as silicon dioxide, and the molar ratio of alkyl orthosilicate, tetraalkyl titanate, tetrapropylammonium hydroxide and water is 1: 0.02~0.05: 0.1~0.3: 20~40.
[0010] In some specific methods for synthesizing titanium silicon molecular sieves, the alkyl groups of the alkyl orthosilicate and the tetraalkyl titanate are independently selected from alkyl groups having 1 to 4 carbon atoms.
[0011] Some specific methods for synthesizing titanium silicalite molecular sieves have a crystallization reaction temperature of 140-160 °C and a crystallization reaction time of 20-50 h.
[0012] Some specific methods for synthesizing titanium silicalite molecular sieves include adding an aqueous solution of alkyl orthosilicate and tetrapropylammonium hydroxide into a reaction tube, allowing the mixture to flow continuously at 0-20°C for 20 min-40 min, and then adding an ethanol solution of tetraalkyl titanate, allowing the mixture to flow continuously at 0-20°C for 20 min-40 min.
[0013] In some specific methods for synthesizing titanium silicon molecular sieves, the tetraalkyl titanate is tetrabutyl titanate, and the alkyl orthosilicate is ethyl orthosilicate.
[0014] Some specific methods for synthesizing titanium silicalite include a drying temperature of 70-100 °C and a drying time of 10-15 h; a calcination temperature of 450-550 °C and a calcination time of 5-20 h.
[0015] The titanium silicalite molecular sieve synthesized by the method described above.
[0016] The titanium silicon molecular sieve is used in catalyzing olefin epoxidation reaction.
[0017] The titanium silicon molecular sieve is used in the reaction of catalyzing propylene epoxidation to prepare propylene oxide.
[0018] Beneficial effects of the present invention: The present invention provides a method for continuous crystallization synthesis of titanium silicon molecular sieve, in which the raw materials for synthesizing titanium silicon molecular sieve are added into a long reaction tube, and a crystallization reaction occurs during continuous flow in the reaction tube, thereby obtaining a titanium silicon molecular sieve with a small grain size and uniform distribution. In addition, a regulator is added in batches during the flow reaction process to further regulate the internal pore structure of the titanium silicon molecular sieve, thereby obtaining a titanium silicon molecular sieve with a rich pore structure and a large specific surface area. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a schematic diagram of a continuous crystallization reaction device.
[0020] Among them, 1. the first storage tank, 2. the second storage tank, 3. the third storage tank, 4. the reaction tube, 5. the first delivery pump, 6. the second delivery pump, 7. the third delivery pump, 8. the cooling tank.
[0021] Figure 2 This is a scanning electron microscope image of the titanium silicon molecular sieve prepared in Example 1. DETAILED DESCRIPTION
[0022] Figure 1 A schematic diagram of a continuous crystallization reaction device is shown. Figure 1 The continuous crystallization reaction device comprises a first storage tank 1, a second storage tank 2, a third storage tank 3 and a reaction tube 4. The materials in the first storage tank 1 and the second storage tank 2 are added to the reaction tube 4 through a first delivery pump 5, and the materials in the third storage tank 3 are added to the reaction tube 4 through a second delivery pump 6. The flow time of the materials in the reaction tube is adjusted by regulating the first delivery pump and the second delivery pump. The outside of the reaction tube is provided with a jacket for passing a heat exchange medium, and the jacket is divided into two sections for passing a heat exchange medium with different temperature requirements. The outlet pipes of the first storage tank 1, the second storage tank 2, and the third storage tank 3 are provided with a flow meter for adjusting the addition amount of each raw material. The interior of the reaction tube 4 can adopt flow channels of different shapes, for example, a baffle type or a serpentine type. The material flowing out of the reaction tube 4 is sent to a cooling tank 8 through a third delivery pump 7.
[0023] Example 1: Add tetraethyl orthosilicate to a first storage tank, add an aqueous solution of tetrapropylammonium hydroxide with a mass concentration of 5.35% to a second storage tank, add an ethanol solution of tetrabutyl titanate with a mass concentration of 30% to a third storage tank, adjust the flow meter to add tetraethyl orthosilicate (in terms of silicon dioxide) and tetrapropylammonium hydroxide to a reaction tube in a molar ratio of 1:0.1, and flow continuously at 15°C in the reaction tube, adjust the speed of the pump so that the reaction mixture flows to the dosing point connected to the third storage tank for 20 min, then add the ethanol solution of tetrabutyl titanate to the reaction tube, adjust the flow meter so that the molar ratio of tetraethyl orthosilicate (in terms of silicon dioxide) to tetrabutyl titanate (in terms of titanium dioxide) is 1:0.03, continue to flow continuously at 15°C for 20 min, then introduce heat transfer oil into the jacket of the reaction tube to maintain the temperature inside the reaction tube at 140°C, and flow the reaction tube at 140°C for 20 min. h later, the reaction mixture flowed into a cooling tank, cooled to room temperature, filtered, washed, dried at 80° C. for 10 h, and calcined at 500° C. for 5 h to obtain a titanium silicalite molecular sieve.
[0024] Example 2: Add tetraethyl orthosilicate to the first storage tank, add an aqueous solution of tetrapropylammonium hydroxide with a mass concentration of 10% to the second storage tank, and add an ethanol solution of tetrabutyl titanate with a mass concentration of 20% to the third storage tank. By adjusting the flow meter, add tetraethyl orthosilicate (in terms of silicon dioxide) and tetrapropylammonium hydroxide to the reaction tube in a molar ratio of 1:0.2, and flow continuously at 15°C in the reaction tube. Adjust the speed of the pump so that the reaction mixture flows to the dosing point connected to the third storage tank for 20 minutes, then add the ethanol solution of tetrabutyl titanate to the reaction tube, adjust the flow meter so that the molar ratio of tetraethyl orthosilicate (in terms of silicon dioxide) to tetrabutyl titanate (in terms of titanium dioxide) is 1:0.02, continue to flow continuously at 15°C for 20 minutes, then pass heat transfer oil into the jacket of the reaction tube to maintain the temperature inside the reaction tube at 140°C, and flow the reaction tube at 140°C for 20 minutes. h later, the reaction mixture flowed into a cooling tank, cooled to room temperature, filtered, washed, dried at 80° C. for 10 h, and calcined at 500° C. for 5 h to obtain a titanium silicalite molecular sieve.
[0025] Example 3: Add tetraethyl orthosilicate to the first storage tank, add an aqueous solution of tetrapropylammonium hydroxide with a mass concentration of 5.35% to the second storage tank, add an ethanol solution of tetrabutyl titanate with a mass concentration of 30% to the third storage tank, adjust the flow meter to add tetraethyl orthosilicate (in terms of silicon dioxide) and tetrapropylammonium hydroxide to the reaction tube in a molar ratio of 1:0.1, and flow continuously at 15°C in the reaction tube. Adjust the speed of the pump so that the reaction mixture flows to the dosing point connected to the third storage tank for 20 min, then add the ethanol solution of tetrabutyl titanate to the reaction tube, adjust the flow meter so that the molar ratio of tetraethyl orthosilicate (in terms of silicon dioxide) to tetrabutyl titanate (in terms of titanium dioxide) is 1:0.03, continue to flow continuously at 15°C for 20 min, then introduce heat transfer oil into the jacket of the reaction tube to maintain the temperature inside the reaction tube at 140°C, and flow the reaction tube at 140°C for 20 min. h later, the reaction mixture flowed into a cooling tank, cooled to room temperature, filtered, washed, dried at 80° C. for 10 h, and calcined at 500° C. for 5 h to obtain a titanium silicalite molecular sieve.
[0026] Example 4: Add tetraethyl orthosilicate to the first storage tank, add an aqueous solution of tetrapropylammonium hydroxide with a mass concentration of 14% to the second storage tank, add an ethanol solution of tetrabutyl titanate with a mass concentration of 15% to the third storage tank, adjust the flow meter to add tetraethyl orthosilicate (calculated as silicon dioxide) and tetrapropylammonium hydroxide to the reaction tube in a molar ratio of 1:0.25, and flow continuously at 20°C in the reaction tube. Adjust the speed of the pump so that the reaction mixture flows to the dosing point connected to the third storage tank for 15 minutes, then add the ethanol solution of tetrabutyl titanate to the reaction tube, adjust the flow meter so that the molar ratio of tetraethyl orthosilicate (calculated as silicon dioxide) to tetrabutyl titanate (calculated as titanium dioxide) is 1:0.04, continue to flow continuously at 20°C for 15 minutes, then introduce heat transfer oil into the jacket of the reaction tube to maintain the temperature inside the reaction tube at 150°C, and flow the reaction tube at 150°C for 18 minutes. h later, the reaction mixture flowed into a cooling tank, cooled to room temperature, filtered, washed, dried at 90° C. for 12 h, and calcined at 550° C. for 5 h to obtain a titanium silicalite molecular sieve.
[0027] Example 5: Add tetraethyl orthosilicate to the first storage tank, add an aqueous solution of tetrapropylammonium hydroxide with a mass concentration of 10% to the second storage tank, add an ethanol solution of tetrabutyl titanate with a mass concentration of 30% to the third storage tank, and add tetraethyl orthosilicate (in terms of silicon dioxide) and tetrapropylammonium hydroxide to the reaction tube in a molar ratio of 1:0.2 by adjusting the flow meter, and flow continuously at 15°C in the reaction tube. Adjust the speed of the pump so that the reaction mixture flows to the dosing point connected to the third storage tank for 20 minutes, then add the ethanol solution of tetrabutyl titanate to the reaction tube, adjust the flow meter so that the molar ratio of tetraethyl orthosilicate (in terms of silicon dioxide) to tetrabutyl titanate (in terms of titanium dioxide) is 1:0.03, continue to flow continuously at 15°C for 20 minutes, and then introduce heat transfer oil into the jacket of the reaction tube to maintain the temperature inside the reaction tube at 140°C, and flow the reaction tube at 160°C for 30 minutes. h later, the reaction mixture flowed into a cooling tank, cooled to room temperature, filtered, washed, dried at 80° C. for 10 h, and calcined at 500° C. for 5 h to obtain a titanium silicalite molecular sieve.
[0028] Example 6: Add tetraethyl orthosilicate to the first storage tank, add an aqueous solution of tetrapropylammonium hydroxide with a mass concentration of 10% to the second storage tank, and add an ethanol solution of tetrabutyl titanate with a mass concentration of 20% to the third storage tank. By adjusting the flow meter, add tetraethyl orthosilicate (calculated as silicon dioxide) and tetrapropylammonium hydroxide to the reaction tube in a molar ratio of 1:0.15, and flow continuously at 10°C in the reaction tube. Adjust the speed of the pump so that the reaction mixture flows to the dosing point connected to the third storage tank for 30 minutes, then add the ethanol solution of tetrabutyl titanate to the reaction tube, adjust the flow meter so that the molar ratio of tetraethyl orthosilicate (calculated as silicon dioxide) to tetrabutyl titanate (calculated as titanium dioxide) is 1:0.05, continue to flow continuously at 10°C for 30 minutes, then pass heat transfer oil into the jacket of the reaction tube to maintain the temperature inside the reaction tube at 170°C, and flow the reaction tube at 170°C for 30 minutes. h later, the reaction mixture flowed into a cooling tank, cooled to room temperature, filtered, washed, dried at 80° C. for 10 h, and calcined at 500° C. for 5 h to obtain a titanium silicalite molecular sieve.
[0029] Example 7: Add tetraethyl orthosilicate to the first storage tank, add an aqueous solution of tetrapropylammonium hydroxide with a mass concentration of 10% to the second storage tank, add an ethanol solution of tetrabutyl titanate with a mass concentration of 20% to the third storage tank, adjust the flow meter to add tetraethyl orthosilicate (in terms of silicon dioxide) and tetrapropylammonium hydroxide to the reaction tube in a molar ratio of 1:0.15, and flow continuously at 25°C in the reaction tube. Adjust the speed of the pump so that the reaction mixture flows to the dosing point connected to the third storage tank for 15 minutes, then add the ethanol solution of tetrabutyl titanate to the reaction tube, adjust the flow meter so that the molar ratio of tetraethyl orthosilicate (in terms of silicon dioxide) to tetrabutyl titanate (in terms of titanium dioxide) is 1:0.04, continue to flow continuously at 25°C for 15 minutes, then introduce heat transfer oil into the jacket of the reaction tube to maintain the temperature inside the reaction tube at 165°C, and flow the reaction tube at 165°C for 35 minutes. h later, the reaction mixture flowed into a cooling tank, cooled to room temperature, filtered, washed, dried at 100° C. for 10 h, and calcined at 500° C. for 5 h to obtain titanium silicalite molecular sieve.
[0030] Example 8: Add tetraethyl orthosilicate to the first storage tank, add an aqueous solution of tetrapropylammonium hydroxide with a mass concentration of 10% to the second storage tank, and add an ethanol solution of tetrabutyl titanate with a mass concentration of 25% to the third storage tank. By adjusting the flow meter, add tetraethyl orthosilicate (in terms of silicon dioxide) and tetrapropylammonium hydroxide to the reaction tube in a molar ratio of 1:0.2, and flow continuously at 15°C in the reaction tube. Adjust the speed of the pump so that the reaction mixture flows to the dosing point connected to the third storage tank for 20 minutes, then add the ethanol solution of tetrabutyl titanate to the reaction tube, adjust the flow meter so that the molar ratio of tetraethyl orthosilicate (in terms of silicon dioxide) to tetrabutyl titanate (in terms of titanium dioxide) is 1:0.03, continue to flow continuously at 15°C for 20 minutes, then pass heat transfer oil into the jacket of the reaction tube to maintain the temperature inside the reaction tube at 160°C, add 5.76g of polyacrylamide at the 6th hour of the flow reaction at 160°C, and continue to react for 24 hours. h, the reaction mixture flows into a cooling tank, is cooled to room temperature, filtered, washed, dried at 80°C for 10 h, and calcined at 500°C for 5 h to obtain titanium silicalite molecular sieve.
[0031] Example 9: Add tetraethyl orthosilicate to the first storage tank, add an aqueous solution of tetrapropylammonium hydroxide with a mass concentration of 10% to the second storage tank, add an ethanol solution of tetrabutyl titanate with a mass concentration of 25% to the third storage tank, and adjust the flow meter to add tetraethyl orthosilicate (in terms of silicon dioxide) and tetrapropylammonium hydroxide to the reaction tube in a molar ratio of 1:0.2, and flow continuously at 15°C in the reaction tube. Adjust the speed of the pump so that the reaction mixture flows to the dosing point connected to the third storage tank for 20 minutes, then add the ethanol solution of tetrabutyl titanate to the reaction tube, adjust the flow meter so that the molar ratio of tetraethyl orthosilicate (in terms of silicon dioxide) to tetrabutyl titanate (in terms of titanium dioxide) is 1:0.03, continue to flow continuously at 15°C for 20 minutes, and then introduce heat transfer oil into the jacket of the reaction tube to maintain the temperature inside the reaction tube at 160°C. 3.6 g of polyacrylamide was added at the 2nd and 7th hours of the flow reaction at 160 °C, and the flow reaction was continued at 160 °C for 23 hours. The reaction mixture was then flowed into a cooling tank, cooled to room temperature, filtered, washed, dried at 80 °C for 10 hours, and calcined at 500 °C for 5 hours to obtain titanium silicalite molecular sieve.
[0032] Example 10: Add tetraethyl orthosilicate to the first storage tank, add an aqueous solution of tetrapropylammonium hydroxide with a mass concentration of 10% to the second storage tank, add an ethanol solution of tetrabutyl titanate with a mass concentration of 25% to the third storage tank, and add tetraethyl orthosilicate (in terms of silicon dioxide) and tetrapropylammonium hydroxide to the reaction tube in a molar ratio of 1:0.2 by adjusting the flow meter, and continuously flow in the reaction tube at 15°C. Adjust the speed of the pump so that the reaction mixture flows to the dosing point connected to the third storage tank for 20 minutes, then add the ethanol solution of tetrabutyl titanate to the reaction tube, adjust the flow meter so that the molar ratio of tetraethyl orthosilicate (in terms of silicon dioxide) to tetrabutyl titanate (in terms of titanium dioxide) is 1:0.03, continue to flow continuously at 15°C for 20 minutes, and then introduce heat transfer oil into the jacket of the reaction tube to maintain the temperature inside the reaction tube at 160°C. 3 g of polyacrylamide was added at 2h, 4h and 8h of the flow reaction at 160°C, and the flow reaction was continued at 160°C for 22 h. The reaction mixture was then flowed into a cooling tank, cooled to room temperature, filtered, washed, dried at 80°C for 10h, and calcined at 500°C for 5h to obtain titanium silicalite molecular sieve.
[0033] Comparative Example 1: 208 g of ethyl orthosilicate was added dropwise to 242 g of an aqueous solution containing 40.67 g of tetrapropylammonium hydroxide, and the mixture was stirred in an ice-water bath for 30 min; 20 g of an ethanol solution containing 8.51 g of tetrabutyl titanate was added dropwise to the reaction mixture of step S1, and the mixture was stirred in an ice-water bath for 30 min. The ethanol and butanol in the reaction mixture were then removed under reduced pressure, 200 g of water was added, the mixture was heated to 180 ° C for crystallization for 50 h, cooled to room temperature, filtered, washed, dried at 100 ° C for 8 h, and calcined at 550 ° C for 5 h to obtain a titanium silicon molecular sieve.
[0034] Comparative Example 2: 208 g of ethyl orthosilicate was added dropwise to 242 g of an aqueous solution containing 40.67 g of tetrapropylammonium hydroxide, and the mixture was stirred in an ice-water bath for 30 min; 20 g of an ethanol solution containing 8.51 g of tetrabutyl titanate was added dropwise to the reaction mixture of step S1, and the mixture was stirred in an ice-water bath for 30 min. The ethanol and butanol in the reaction mixture were then removed under reduced pressure, 200 g of water and 5.76 g of polyacrylamide were added, the mixture was heated to 180 ° C for crystallization for 50 h, cooled to room temperature, filtered, washed, dried at 100 ° C for 8 h, and calcined at 550 ° C for 5 h to obtain a titanium silicon molecular sieve.
[0035] Test Example: A scanning electron microscope (Hitachi, SU5000) was used to analyze the grain morphology and size of the titanium silicon molecular sieve obtained in Example 1-10 and Comparative Example 1-2, and an ASAP 2460 specific surface and pore size analyzer was used to analyze the specific surface and pore size of the titanium silicon molecular sieve obtained in Example 1-10 and Comparative Example 1-2. The specific surface area of the sample was calculated using the BET equation, and the mesopore volume was calculated using the BJH model. The specific data are shown in Table 1. Table 1 Pore diameter and particle size of titanium silicon molecular sieves in Examples and Comparative Examples sample Mesopore diameter / nm <![CDATA[Mesopore volume / cm 3 / g]]> <![CDATA[Specific surface area / cm 2 / g]]> Particle size / nm Example 1 — — 375 100~150 Example 2 — — 378 100~150 Example 3 — — 387 100~150 Example 4 — — 379 100~150 Example 5 — — 387 100~150 Example 6 — — 381 100~150 Example 7 — — 385 100~150 Example 8 2~5 nm 0.30 437 100~160 Example 10 2~5 nm 0.41 475 100~160 Comparative Example 1 — — 373 140~200 Comparative Example 2 — — 396 140~210 It can be seen from the data in Table 1 that, compared with conventional methods, the present invention obtains a titanium silicon molecular sieve with a small particle size and a rich pore structure and a large specific surface area through continuous reaction in a raw material pipeline.
Claims
1. A method for continuous crystallization synthesis of titanium silicon molecular sieve, characterized in that: Use the following steps: An aqueous solution of alkyl orthosilicate and tetrapropylammonium hydroxide for preparing titanium silicon molecular sieve is added to a reaction tube, and continuously flows at 0-30°C in the reaction tube. After flowing for 10 min-40 min, an ethanol solution of tetraalkyl titanate is added to the reaction tube, and continuously flows at 0-30°C for 10 min-40 min. After that, the solution is continuously flowed at 130-180°C in the reaction tube for 10-50 h. The solution is cooled to room temperature, filtered, washed, dried, and calcined to obtain the titanium silicon molecular sieve.
2. The method for synthesizing titanium silicon molecular sieve according to claim 1, characterized in that: Add additives at least once during continuous flow at 130-180 °C for 1-9 hours; The auxiliary agent is polyacrylamide, and the mass ratio of alkyl orthosilicate to the auxiliary agent is 1:0.01-0.08 based on silicon dioxide.
3. The method for synthesizing titanium silicon molecular sieve according to claim 2, characterized in that: Add the additives to the reaction tube after continuous flow at 130-180 °C for 1-2 h, 3-5 h, and 6-9 h respectively; The mass ratio of alkyl orthosilicate to the additive is 1:0.02~0.05 based on silicon dioxide.
4. The method for synthesizing titanium silicon molecular sieve according to any one of claims 1 to 3, characterized in that: The tetraalkyl titanate is calculated as titanium dioxide, the alkyl orthosilicate is calculated as silicon dioxide, and the molar ratio of the alkyl orthosilicate, the tetraalkyl titanate, the tetrapropylammonium hydroxide and the water is 1: 0.02-0.05: 0.1-0.3: 20-40.
5. The method for synthesizing titanium silicon molecular sieve according to claim 4, characterized in that: The alkyl groups of the alkyl orthosilicate and tetraalkyl titanate are independently selected from alkyl groups having 1 to 4 carbon atoms.
6. The method for synthesizing titanium silicon molecular sieve according to any one of claims 1 to 3, characterized in that: The temperature of the crystallization reaction is 140~160 ℃, and the crystallization reaction time is 20~50 h.
7. The method for synthesizing titanium silicon molecular sieve according to any one of claims 1 to 3, characterized in that: An aqueous solution of alkyl orthosilicate and tetrapropylammonium hydroxide is added to a reaction tube, and continuously flows at 0-20°C for 20 min-40 min. Then, an ethanol solution of tetraalkyl titanate is added, and continuously flows at 0-20°C for 20 min-40 min.
8. The method for synthesizing titanium silicon molecular sieve according to any one of claims 1 to 3, characterized in that: The tetraalkyl titanate is tetrabutyl titanate, and the alkyl orthosilicate is ethyl orthosilicate.
9. The method for synthesizing titanium silicon molecular sieve according to any one of claims 1 to 5, characterized in that: The drying temperature is 70~100 ℃, and the drying time is 10~15 h; the roasting temperature is 450~550 ℃, and the roasting time is 5~20 h.
10. Titanium silicon molecular sieve synthesized according to the method according to any one of claims 1 to 5.