Preparation method and application of titanium silicalite molecular sieve TS-2

Abstract

The invention discloses a preparation method and application of a titanium silicalite molecular sieve TS-2, and belongs to the technical field of molecular sieves. The preparation method specifically comprises the following steps: (1) adding quaternary ammonium base and quaternary ammonium salt into water, and mixing and stirring; (2) adding a silicon source, mixing and stirring; (3) adding an isopropanol solution of a titanium source, and stirring for hydrolysis; (4) heating and stirring, and heating and crystallizing; and (5) cooling, filtering, washing, drying and roasting. The preparation method comprises the following steps: regulating the pH value to be lower than 12 through a composite template agent (quaternary ammonium base and quaternary ammonium salt), enabling the concentration of tetrabutylammonium cations of a system to be in a relatively high state, and preparing a titanium silicalite molecular sieve TS-2, 3-dibromo-2, 3-dibromo-2, 3-dibromo-2, 3-dibromo-2, 3-dibromo-2, 3-dibromo-2, 3-dibromo-2, 3-dibromo-2, 3-dibromo-2, 3-dibromo-2, 3-dibromo-2, 3-dibromo-2, 3-dibromo-2, 3-dibromo-2, 3- The catalyst has high mass transfer efficiency and high catalytic performance.

Description

Technical Field

[0001] The present invention relates to the technical field of molecular sieves, and more particularly to a preparation method and application of titanium silicate molecular sieve TS-2. Background Art

[0002] Titanium silicate molecular sieve, as a heteroatom molecular sieve, is a catalytic material with great potential formed by the entry of Ti element into the molecular sieve framework. It not only retains the catalytic properties of the heteroatom itself, but also combines the inherent advantages of molecular sieves. Compared with traditional molecular sieves, it has richer structural composition and functional modification, and its catalytic performance can be controlled by adjusting the content and position of heteroatoms.

[0003] As the first titanium silicalite molecular sieve invented, TS-1 has been widely used in reactions such as olefin epoxidation, aromatic hydroxylation, and ketone ammoximation using hydrogen peroxide as the oxidant. This enables the oxidation process to achieve high efficiency and selectivity under mild conditions, while being environmentally friendly. Subsequently, titanium-containing molecular sieves with different topologies, such as TS-2, Ti-Beta, Ti-MOR, and Ti-MWW, have emerged.

[0004] Titanium silicate TS-2 has a MEL topology. MEL molecular sieves were first prepared in 1990 by Indian scientist J. Sudhakar et al. using a traditional hydrothermal synthesis method using tetrabutylammonium hydroxide (TBAOH) as a template, tetraethyl orthosilicate (TEOS) as a silicon source, and tetraethyl titanate (TBOT) as a titanium source. Its structure is very similar to the widely used MFI structure, both featuring a three-dimensional pentasil chain structure with ten-membered ring channels. However, their pore configurations differ. The MEL pore structure consists of two groups of perpendicular straight channels, while the MFI pore structure consists of a group of straight channels intersecting with a group of sinusoidal channels.

[0005] Previous studies have found that titanium silicate molecular sieve TS-2 has two morphologies: a relatively unique stacked microsphere structure (approximately 10 μm) and a submicron granular structure (approximately 300 nm) similar to ordinary molecular sieves. The diameter of the microsphere is approximately 30 times that of the submicron granular structure. The morphology of titanium silicate molecular sieve TS-2 is related to the pH value of the hydrothermal gel system. When the pH value of the hydrothermal gel system is high (specific value), TS-2 forms a stacked microsphere structure; when the pH is low, TS-2 forms a submicron granular structure. TS-2 with a stacked microsphere structure has more titanium active centers and better catalytic performance; TS-2 with a submicron granular structure has a higher mass transfer efficiency in catalytic reactions due to its smaller particles, which facilitate molecular diffusion.

[0006] Therefore, how to develop a titanium silicate molecular sieve TS-2 with both high mass transfer efficiency and high catalytic performance is an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the object of the present invention is to provide a preparation method of titanium silicate molecular sieve TS-2 and its application to solve the deficiencies in the prior art.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for preparing titanium silicate molecular sieve TS-2 specifically comprises the following steps:

[0010] (1) adding a quaternary ammonium base and a quaternary ammonium salt to water, mixing and stirring to obtain a solution A;

[0011] (2) adding a silicon source to solution A, mixing and stirring to obtain solution B;

[0012] (3) adding the isopropanol solution of the titanium source to solution B, stirring and hydrolyzing to obtain solution C;

[0013] (4) heating and stirring the solution C in sequence, and crystallizing the solution in a sealed pressure vessel to obtain a crystallized product;

[0014] (5) The crystallized product is cooled, filtered, washed, dried, and calcined in sequence to obtain titanium silicate molecular sieve TS-2.

[0015] Furthermore, in the above step (1), the quaternary ammonium base is at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide, preferably tetrabutylammonium hydroxide; the quaternary ammonium salt is at least one of quaternary ammonium chloride, quaternary ammonium bromide, quaternary ammonium sulfate, quaternary ammonium phosphate and quaternary ammonium perchlorate (the quaternary ammonium ion is composed of four identical alkyl groups, each alkyl group is independently selected from an alkyl group with 1 to 4 carbon atoms), preferably at least one of tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium sulfate, tetrabutylammonium phosphate and tetrabutylammonium perchlorate; at least one of the quaternary ammonium base and the quaternary ammonium salt must be an alkyl group with 4 carbon atoms in the alkyl chain; the mixing and stirring temperature is 10 to 60° C., and the time is 5 to 120 minutes.

[0016] Furthermore, in the above step (2), the silicon source is at least one of an alkyl orthosilicate (the alkyl groups are independently selected from an alkyl group having 1 to 4 carbon atoms), silica sol and white carbon black, preferably an alkyl orthosilicate (the alkyl groups are independently selected from an alkyl group having 1 to 4 carbon atoms), and more preferably tetraethyl silicate; and the mixing and stirring time is 5 to 120 minutes.

[0017] Furthermore, in the above step (3), the titanium source is an alkyl titanate (the alkyl groups are independently selected from alkyl groups with 1 to 4 carbon atoms), preferably at least one of tetraethyl titanate and tetrabutyl titanate; and the stirring and hydrolysis time is 5 to 120 minutes.

[0018] Furthermore, in the above steps (1)-(3), the molar ratio of the quaternary ammonium base, the quaternary ammonium salt, water, the silicon source (calculated as SiO2), the titanium source (calculated as TiO2) and the isopropanol solution is (0.1-0.5):(0.1-0.5):(5-100):1:(0.01-0.05):(0.01-4).

[0019] Furthermore, in the above step (4), the temperature of the heating and stirring is 90° C., and the time is 1 to 12 hours; the equipment for heating and crystallization is a closed container, the temperature is 120 to 180° C., and the time is 12 to 200 hours.

[0020] Furthermore, in the above step (5), the washing reagent is deionized water, and the number of times is three times; the drying equipment is a drying oven, the temperature is 80-100° C., to constant weight; the roasting temperature is 550-580° C., and the time is 5-8 hours.

[0021] The present invention also seeks to protect a titanium silicon molecular sieve TS-2 prepared by the above preparation method.

[0022] The present invention also claims protection for the use of the titanium silicon molecular sieve TS-2 prepared by the above preparation method in catalyzing olefin epoxidation reactions, catalyzing aromatic hydrocarbon hydroxylation reactions, and catalyzing aldehyde and ketone ammoxidation reactions.

[0023] The present invention also seeks to protect the use of the titanium silicalite TS-2 prepared by the above preparation method in catalyzing the epoxidation of propylene to produce propylene oxide, catalyzing the hydroxylation of phenol to produce diphenol, and catalyzing the ammoximation of cyclohexanone to produce cyclohexanone oxime.

[0024] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The present invention uses a composite template (quaternary ammonium base and quaternary ammonium salt) to regulate the pH to below 12, while keeping the tetrabutylammonium cation concentration of the system at a high state. Through a conventional hydrothermal synthesis process, a titanium silicalite TS-2 having a submicron grain morphology (diameter of 300-500nm) and more titanium active centers is prepared, achieving both high mass transfer efficiency and high catalytic performance.

[0026] 2. The present invention adopts a mixed template strategy and uses quaternary ammonium salt (tetrabutylammonium salt) to regulate the pH value of the hydrothermal gel, the morphology, dispersion, the state of Ti entering the molecular sieve framework and the microscopic pore structure of the titanium silicate molecular sieve TS-2, so as to obtain a submicron granular titanium silicate molecular sieve TS-2 with higher mass transfer efficiency and higher dispersion of Ti elements.

[0027] 3. The present invention prepares a submicron granular titanium silicon molecular sieve TS-2 with higher catalytic activity and higher diffusion performance by simultaneously adjusting the pH value of the gel and the ratio of quaternary ammonium ions (tetrabutylammonium cations) to SiO2. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a scanning electron microscope image of the titanium silicate molecular sieve TS-2 prepared in Example 1;

[0029] Figure 2 This is a scanning electron microscope image of the titanium silicate molecular sieve TS-2 prepared in Comparative Example 1;

[0030] Figure 3 This is a scanning electron microscope image of the titanium silicate molecular sieve TS-2 prepared in Comparative Example 2. DETAILED DESCRIPTION

[0031] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0032] Example 1

[0033] The preparation method of titanium silicate molecular sieve TS-2 specifically comprises the following steps:

[0034] (1) 20 g of 40% tetrabutylammonium hydroxide solution and 2 g of tetrabutylammonium chloride were mixed, added to deionized water, and stirred at 40° C. for 1 h to obtain solution A;

[0035] (2) Add 20 g of tetraethyl orthosilicate to solution A and stir for 2 h to obtain solution B;

[0036] (3) Add 5 g of isopropyl alcohol and 0.35 g of tetrabutyl titanate to solution B and stir for hydrolysis for 1 h to obtain solution C;

[0037] (4) Solution C was first stirred at 90°C for 8 h to obtain a primary gel of titanium silicalite, and then transferred to a crystallization kettle and crystallized at 170°C for 72 h to obtain a crystallized product;

[0038] (5) The crystallized product was cooled to room temperature, filtered, washed three times with deionized water, dried at 100°C to constant weight, and calcined at 550°C for 6 h to obtain titanium silicate molecular sieve TS-2.

[0039] Example 2

[0040] The preparation method of titanium silicate molecular sieve TS-2 specifically comprises the following steps:

[0041] (1) 40 g of 25% by mass tetrapropylammonium hydroxide solution and 13.5 g of tetrabutylammonium chloride were mixed, added to deionized water, and stirred at 10° C. for 2 h to obtain solution A;

[0042] (2) Add 20 g of tetraethyl orthosilicate to solution A and stir for 10 min to obtain solution B;

[0043] (3) Add 24 g of isopropyl alcohol and 1.6 g of tetrabutyl titanate to solution B and stir for hydrolysis for 10 min to obtain solution C;

[0044] (4) Solution C was stirred at 90°C for 10 h to obtain a primary gel of titanium silicalite, and then transferred to a crystallization reactor and crystallized at 180°C for 150 h to obtain a crystallized product;

[0045] (5) The crystallized product was cooled to room temperature, filtered, washed three times with deionized water, dried at 100°C to constant weight, and calcined at 550°C for 6 h to obtain titanium silicate molecular sieve TS-2.

[0046] Example 3

[0047] The preparation method of titanium silicate molecular sieve TS-2 specifically comprises the following steps:

[0048] (1) 8 g of 40% by mass tetrabutylammonium hydroxide solution and 4 g of tetrapropylammonium bromide were mixed, added to deionized water, and stirred at 60° C. for 1 h to obtain solution A;

[0049] (2) Add 20 g of tetraethyl orthosilicate to solution A and stir for 30 min to obtain solution B;

[0050] (3) Add 15 g of isopropyl alcohol and 0.55 g of tetraethyl titanate to solution B and stir for hydrolysis for 2 h to obtain solution C;

[0051] (4) Solution C was stirred at 90°C for 5 h to obtain a primary gel of titanium silicate molecular sieve, and then transferred to a crystallization reactor and crystallized at 180°C for 48 h to obtain a crystallized product;

[0052] (5) The crystallized product was cooled to room temperature, filtered, washed three times with deionized water, dried at 100°C to constant weight, and calcined at 550°C for 6 h to obtain titanium silicate molecular sieve TS-2.

[0053] Example 4

[0054] The preparation method of titanium silicate molecular sieve TS-2 specifically comprises the following steps:

[0055] (1) 12 g of a 40% by mass tetrabutylammonium hydroxide solution and 1 g of tetrabutylammonium bromide were mixed, added to deionized water, and stirred at 30° C. for 5 min to obtain solution A;

[0056] (2) Add 23 g of 30% silica sol to solution A and stir for 10 min to obtain solution B;

[0057] (3) Add 3 g of isopropyl alcohol and 0.5 g of tetrabutyl titanate to solution B and stir for hydrolysis for 2 h to obtain solution C;

[0058] (4) Solution C was stirred at 90°C for 1 h to obtain a primary gel of titanium silicalite, and then transferred to a crystallization reactor and crystallized at 170°C for 60 h to obtain a crystallized product;

[0059] (5) The crystallized product was cooled to room temperature, filtered, washed three times with deionized water, dried at 100°C to constant weight, and calcined at 550°C for 6 h to obtain titanium silicate molecular sieve TS-2.

[0060] Example 5

[0061] The preparation method of titanium silicate molecular sieve TS-2 specifically comprises the following steps:

[0062] (1) 25 g of 40% tetrabutylammonium hydroxide solution and 3 g of tetrabutylammonium phosphate were mixed, added to deionized water, and stirred at 20° C. for 30 min to obtain solution A;

[0063] (2) Add 20 g of tetraethyl orthosilicate to solution A and stir for 1 h to obtain solution B;

[0064] (3) Add 2 g of isopropyl alcohol and 1.2 g of tetrabutyl titanate to solution B and stir for hydrolysis for 30 min to obtain solution C;

[0065] (4) Solution C was first stirred at 90°C for 8 hours to obtain a primary gel of titanium silicalite molecular sieve, and then transferred to a crystallization kettle and crystallized at 140°C for 180 hours to obtain a crystallized product;

[0066] (5) The crystallized product was cooled to room temperature, filtered, washed three times with deionized water, dried at 100°C to constant weight, and calcined at 550°C for 6 h to obtain titanium silicate molecular sieve TS-2.

[0067] Example 6

[0068] The preparation method of titanium silicate molecular sieve TS-2 specifically comprises the following steps:

[0069] (1) 8 g of 40% by mass tetrabutylammonium hydroxide solution and 1 g of tetrabutylammonium perchlorate were mixed, added to deionized water, and stirred at 50° C. for 5 min to obtain solution A;

[0070] (2) Add 20 g of tetraethyl orthosilicate to solution A and stir for 10 min to obtain solution B;

[0071] (3) Add 15 g of isopropyl alcohol and 0.4 g of tetraethyl titanate to solution B and stir for hydrolysis for 5 min to obtain solution C;

[0072] (4) Solution C was stirred at 90°C for 12 hours to obtain a primary gel of titanium silicate molecular sieve, and then transferred to a crystallization reactor and crystallized at 120°C for 120 hours to obtain a crystallized product;

[0073] (5) The crystallized product was cooled to room temperature, filtered, washed three times with deionized water, dried at 100°C to constant weight, and calcined at 550°C for 6 h to obtain titanium silicate molecular sieve TS-2.

[0074] Example 7

[0075] The preparation method of titanium silicate molecular sieve TS-2 specifically comprises the following steps:

[0076] (1) 10 g of 40% tetrabutylammonium hydroxide solution and 2 g of tetrabutylammonium bromide were mixed, added to deionized water, and stirred at 20° C. for 1 h to obtain solution A;

[0077] (2) Add 6 g of white carbon black to solution A and stir for 2 h to obtain solution B;

[0078] (3) Add 5 g of isopropyl alcohol and 1.5 g of tetrabutyl titanate to solution B and stir for 20 min to obtain solution C.

[0079] (4) Solution C was stirred at 90°C for 5 h to obtain a primary gel of titanium silicate molecular sieve, and then transferred to a crystallization reactor and crystallized at 170°C for 24 h to obtain a crystallized product;

[0080] (5) The crystallized product was cooled to room temperature, filtered, washed three times with deionized water, dried at 100°C to constant weight, and calcined at 550°C for 6 h to obtain titanium silicate molecular sieve TS-2.

[0081] Example 8

[0082] The preparation method of titanium silicate molecular sieve TS-2 specifically comprises the following steps:

[0083] (1) 15 g of 40% tetrabutylammonium hydroxide solution and 1 g of tetraethylammonium sulfate were mixed, added to deionized water, and stirred at 40° C. for 5 min to obtain solution A;

[0084] (2) Add 20 g of tetraethyl orthosilicate to solution A and stir for 5 min to obtain solution B;

[0085] (3) Add 5 g of isopropyl alcohol and 1.7 g of tetrabutyl titanate to solution B and stir for hydrolysis for 30 min to obtain solution C;

[0086] (4) Solution C was first stirred at 90°C for 4 hours to obtain a primary gel of titanium silicate molecular sieve, and then transferred to a crystallization kettle and crystallized at 150°C for 72 hours to obtain a crystallized product;

[0087] (5) The crystallized product was cooled to room temperature, filtered, washed three times with deionized water, dried at 100°C to constant weight, and calcined at 550°C for 6 h to obtain titanium silicate molecular sieve TS-2.

[0088] Example 9

[0089] The preparation method of titanium silicate molecular sieve TS-2 specifically comprises the following steps:

[0090] (1) 13 g of 40% tetrabutylammonium hydroxide solution and 1.5 g of tetrabutylammonium sulfate were mixed, added to deionized water, and stirred at 25° C. for 1 h to obtain solution A;

[0091] (2) Add 20 g of tetraethyl orthosilicate to solution A and stir for 2 h to obtain solution B;

[0092] (3) Add 1.5 g of tetraethyl titanate to solution B and stir for 30 min to obtain solution C;

[0093] (4) Solution C was first stirred at 90°C for 4 hours to obtain a primary gel of titanium silicate molecular sieve, and then transferred to a crystallization kettle and crystallized at 160°C for 96 hours to obtain a crystallized product;

[0094] (5) The crystallized product was cooled to room temperature, filtered, washed three times with deionized water, dried at 100°C to constant weight, and calcined at 550°C for 6 h to obtain titanium silicate molecular sieve TS-2.

[0095] Example 10

[0096] The preparation method of titanium silicate molecular sieve TS-2 specifically comprises the following steps:

[0097] (1) 25 g of 25% by mass tetraethylammonium hydroxide solution and 16 g of tetrabutylammonium chloride were mixed, added to deionized water, and stirred at 10° C. for 1 h to obtain solution A;

[0098] (2) Add 23 g of 30% silica sol to solution A and stir for 2 h to obtain solution B;

[0099] (3) Add 20 g of isopropyl alcohol and 1 g of tetrabutyl titanate to solution B and stir for hydrolysis for 2 h to obtain solution C;

[0100] (4) Solution C was stirred at 90°C for 6 h to obtain a primary gel of titanium silicate molecular sieve, and then transferred to a crystallization reactor and crystallized at 180°C for 120 h to obtain a crystallized product;

[0101] (5) The crystallized product was cooled to room temperature, filtered, washed three times with deionized water, dried at 100°C to constant weight, and calcined at 550°C for 6 h to obtain titanium silicate molecular sieve TS-2.

[0102] Example 11

[0103] The preparation method of titanium silicate molecular sieve TS-2 specifically comprises the following steps:

[0104] (1) 25 g of 25% by mass tetramethylammonium hydroxide solution and 16 g of tetrabutylammonium bromide were mixed, added to deionized water, and stirred at 15° C. for 30 min to obtain solution A;

[0105] (2) Add 20 g of tetraethyl orthosilicate to solution A and stir for 2 h to obtain solution B;

[0106] (3) Add 8 g of isopropyl alcohol and 1 g of tetraethyl titanate to solution B and stir for hydrolysis for 30 min to obtain solution C;

[0107] (4) Solution C was stirred at 90°C for 12 h to obtain a primary gel of titanium silicalite, and then transferred to a crystallization reactor and crystallized at 170°C for 200 h to obtain a crystallized product;

[0108] (5) The crystallized product was cooled to room temperature, filtered, washed three times with deionized water, dried at 100°C to constant weight, and calcined at 550°C for 6 h to obtain titanium silicate molecular sieve TS-2.

[0109] Example 12

[0110] The preparation method of titanium silicate molecular sieve TS-2 specifically comprises the following steps:

[0111] (1) 29 g of a 40% by mass tetrabutylammonium hydroxide solution and 15 g of tetramethylammonium bromide were mixed, added to deionized water, and stirred at 30° C. for 40 min to obtain solution A;

[0112] (2) Add 20 g of tetraethyl orthosilicate to solution A and stir for 10 min to obtain solution B;

[0113] (3) Add 10 g of isopropyl alcohol and 1 g of tetrabutyl titanate to solution B and stir for 40 min to obtain solution C.

[0114] (4) Solution C was stirred at 90°C for 10 h to obtain a primary gel of titanium silicate molecular sieve, and then transferred to a crystallization reactor and crystallized at 170°C for 12 h to obtain a crystallized product;

[0115] (5) The crystallized product was cooled to room temperature, filtered, washed three times with deionized water, dried at 100°C to constant weight, and calcined at 550°C for 6 h to obtain titanium silicate molecular sieve TS-2.

[0116] Comparative Example 1

[0117] The preparation method of titanium silicate molecular sieve TS-2 specifically comprises the following steps:

[0118] (1) Add 25 g of 40% tetrabutylammonium hydroxide solution to deionized water and stir for 1 h to obtain solution A;

[0119] (2) Add 20 g of tetraethyl orthosilicate to solution A and stir for 2 h to obtain solution B;

[0120] (3) Add 15 g of isopropyl alcohol and 1 g of tetrabutyl titanate to solution B and stir for hydrolysis for 1 h to obtain solution C;

[0121] (4) Solution C was first stirred at 90°C for 8 h to obtain a primary gel of titanium silicalite, and then transferred to a crystallization kettle and crystallized at 170°C for 72 h to obtain a crystallized product;

[0122] (5) The crystallized product was cooled to room temperature, filtered, washed three times with deionized water, dried at 100°C to constant weight, and calcined at 550°C for 6 h to obtain titanium silicate molecular sieve TS-2.

[0123] Comparative Example 2

[0124] The preparation method of titanium silicate molecular sieve TS-2 specifically comprises the following steps:

[0125] (1) Add 8 g of 40% tetrabutylammonium hydroxide solution to deionized water and stir for 1 h to obtain solution A;

[0126] (2) Add 20 g of tetraethyl orthosilicate to solution A and stir for 2 h to obtain solution B;

[0127] (3) Add 2 g of isopropyl alcohol and 1.5 g of tetrabutyl titanate to solution B and stir for hydrolysis for 1 h to obtain solution C;

[0128] (4) Solution C was first stirred at 90°C for 8 h to obtain a primary gel of titanium silicalite, and then transferred to a crystallization kettle and crystallized at 170°C for 72 h to obtain a crystallized product;

[0129] (5) The crystallized product was cooled to room temperature, filtered, washed three times with deionized water, dried at 100°C to constant weight, and calcined at 550°C for 6 h to obtain titanium silicate molecular sieve TS-2.

[0130] Performance Testing

[0131] 1. Scanning electron microscope image

[0132] The scanning electron microscope images of titanium silicon molecular sieve TS-2 prepared in Example 1 and Comparative Examples 1-2 are shown as follows: Figure 1-3 shown.

[0133] Depend on Figure 1-3 It can be seen that the morphology of the titanium silicate molecular sieve TS-2 in Example 1 is submicron grain-shaped, the morphology of the titanium silicate molecular sieve TS-2 in Comparative Example 1 is stacked microspheres, and the morphology of the titanium silicate molecular sieve TS-2 in Comparative Example 2 is submicron grain-shaped.

[0134] 2. pH value, relative crystallinity and morphology

[0135] The titanium silicate primary gel and titanium silicate TS-2 samples prepared in Examples 1-12 and Comparative Examples 1-2 were taken respectively, the pH values ​​of the titanium silicate primary gels were measured, the relative crystallinity of the titanium silicate TS-2 was calculated, and the morphology of the titanium silicate TS-2 was observed using a scanning electron microscope.

[0136] Relative crystallinity: The crystallinity of the titanium silicate molecular sieve TS-2 sample prepared in Comparative Example 1 is 100%, and the relative crystallinity of other molecular sieve samples is calculated.

[0137] The results are shown in Table 1.

[0138] Table 1 pH value of titanium silicate primary gel and relative crystallinity and morphology of titanium silicate TS-2

[0139]

[0140]

[0141] It can be seen from Table 1 that when the pH value of the titanium silicalite primary gel is less than 12.0, the morphology of the prepared titanium silicalite TS-2 is submicron crystalline; when the pH value of the titanium silicalite primary gel is greater than 12.6, the morphology of the prepared titanium silicalite TS-2 is stacked microspheres; when the pH value of the titanium silicalite primary gel is between 12.0 and 12.6, the morphology of the prepared titanium silicalite TS-2 is a coexistence of stacked microspheres and submicron crystalline.

[0142] 3. Phenol hydroxylation reaction effect test

[0143] The phenol hydroxylation reaction was carried out in a 250 mL three-necked flask reactor equipped with an automatic temperature-controlled water bath, magnetic stirring, and a condensation reflux system. 0.3 g of the titanium silicalite TS-2 sample prepared in Examples 1-12 and Comparative Examples 1-2, 12 g (0.375 mol) of methanol solvent, and 3 g (0.03 mol) of phenol were added to the three-necked flask, with a catalyst-to-phenol mass ratio of 0.1. The flask was placed in a water bath set at a reaction temperature of 70°C. 1.14 g (0.01 mol) of 30% hydrogen peroxide was added dropwise using a syringe, with a molar ratio of phenol, hydrogen peroxide, and methanol solvent of 3:1:37.5. The reaction was continued for 1 hour, then stopped, the temperature was rapidly lowered, and the liquid product was separated by filtration. The composition was determined, and the phenol conversion rate, catechol selectivity, hydroquinone selectivity, and p-benzoquinone selectivity were calculated.

[0144] Phenol conversion (%) = (moles of phenol in the raw material - moles of phenol in the product) / moles of phenol in the raw material × 100%;

[0145] Selectivity of catechol (%) = moles of catechol produced in the product / moles of phenol consumed in producing all products × 100%;

[0146] Hydroquinone selectivity (%) = number of moles of hydroquinone produced in the product / number of moles of phenol consumed in producing all products × 100%;

[0147] Selectivity for p-benzoquinone (%) = number of moles of p-benzoquinone produced in the product / number of moles of phenol consumed to produce all products × 100%.

[0148] The results are shown in Table 2.

[0149] Table 2 Test results of phenol hydroxylation reaction of titanium silicalite TS-2 in Examples 1-12 and Comparative Examples 1-2

[0150]

[0151] As shown in Table 2, compared with Comparative Examples 1-2, the modification method using a composite template in Examples 1-12 significantly improves the catalytic activity of titanium silicalite TS-2 in the phenol hydroxylation reaction while changing its morphology. Furthermore, the method for preparing titanium silicalite TS-2 using a composite template in Examples 1-12 does not affect the crystallization of the molecular sieve.

[0152] 4. Propylene epoxidation reaction effect test

[0153] Propylene epoxidation was conducted in a 250 mL batch reactor with mechanical stirring. Propylene was introduced into a mixture of 0.2 g of titanium silicalite TS-2 prepared in Examples 1-12 and Comparative Examples 1-2, respectively, and a H2O2 / methanol solution (H2O2 concentration c(H2O2) = 3.0 mol / L). Stirring and heating were initiated, and the reactants were allowed to react at 40°C for 1 hour. After completion of the reaction, the temperature was rapidly lowered, and the liquid product was filtered and separated. The composition was determined, and the residual H2O2 content was determined using indirect iodine titration. The hydrogen peroxide conversion and propylene oxide selectivity were calculated.

[0154] Wherein, hydrogen peroxide conversion rate (%) = (moles of hydrogen peroxide in the raw material - moles of hydrogen peroxide in the product) / moles of hydrogen peroxide in the raw material × 100%;

[0155] Propylene oxide selectivity (%) = the number of moles of propylene oxide produced in the product / (the number of moles of propylene oxide produced in the product + the number of moles of propylene glycol methyl ether produced in the product + the number of moles of propylene glycol produced in the product) × 100%.

[0156] The results are shown in Table 3.

[0157] Table 3 Propylene epoxidation test results of Examples 1-12 and Comparative Examples 1-2 Titanium Silicate Molecular Sieve TS-2

[0158] serial number Hydrogen peroxide conversion rate, % Propylene oxide selectivity, % 1 41.2 97.1 2 39.5 96.2 3 40.3 98.1 4 36.8 95.7 5 37.9 93.6 6 38.1 95.4 7 39.2 97.7 8 35.4 91.2 9 40.1 96.3 10 37.8 97.8 11 38.6 98.3 12 37.4 95.8 D1 36.7 96.5 D2 32.5 92.7

[0159] As shown in Table 3, compared with Comparative Examples 1-2, the modification method using a composite template in Examples 1-12 significantly improves the catalytic activity of titanium silicalite TS-2 for propylene epoxidation while changing its morphology. Furthermore, the method for preparing titanium silicalite TS-2 using a composite template in Examples 1-12 does not affect the crystallization of the molecular sieve.

[0160] 5. Cyclohexanone ammoximation reaction effect test

[0161] The cyclohexanone ammoximation reaction was carried out in a 50 mL three-necked flask reaction apparatus with an automatic temperature-controlled water bath, magnetic stirring, and condensation reflux system. 0.075 g of the titanium silicate TS-2 sample obtained in Examples 1-12 and Comparative Examples 1-2, 7.5 g (0.4 mol) of solvent water, 0.2 g (0.02 mol) of cyclohexanone, 6 g of tert-butanol, and 0.55 g of aqueous ammonia were added to a three-necked flask, with a catalyst to cyclohexanone mass ratio of 0.1. The flask was placed in a water bath with a preset reaction temperature of 70°C, and 0.25 g (0.02 mol) of 30% hydrogen peroxide was added dropwise using a syringe, with a molar ratio of cyclohexanone to hydrogen peroxide of 1:1. The reaction was stopped after 1.5 h, the temperature was rapidly lowered, and the liquid product was separated by filtration. The composition was determined, and the cyclohexanone conversion rate and cyclohexanone oxime selectivity were calculated.

[0162] Wherein, cyclohexanone conversion rate (%) = (cyclohexanone mole number in raw material - cyclohexanone mole number in product) / cyclohexanone mole number in raw material × 100%;

[0163] Cyclohexanone oxime selectivity (%) = the number of moles of cyclohexanone oxime produced in the product / the number of moles of cyclohexanone consumed to produce all products × 100%.

[0164] The results are shown in Table 4.

[0165] Table 4 Test results of cyclohexanone ammoximation reaction of titanium silicalite TS-2 in Examples 1-12 and Comparative Examples 1-2

[0166] serial number Cyclohexanone conversion, % Cyclohexanone oxime selectivity, % 1 97.3 99.5 2 95.4 97.3 3 96.4 98.2 4 94.8 96.1 5 93.6 98,5 6 92.7 99.5 7 89.7 99.6 8 93.2 95.8 9 94.1 94.3 10 92.5 98.7 11 93.4 99.5 12 91.5 98.4 D1 92.7 99.1 D2 88.4 95.2

[0167] As shown in Table 4, compared with Comparative Examples 1-2, the modification method using a composite template in Examples 1-12 significantly improves the catalytic activity of titanium silicalite TS-2 in the ammoximation reaction of cyclohexanone while changing its morphology. Furthermore, the method for preparing titanium silicalite TS-2 using a composite template in Examples 1-12 does not affect the crystallization of the molecular sieve.

[0168] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing titanium silicate molecular sieve TS-2, characterized in that: The specific steps include: (1) adding a quaternary ammonium base and a quaternary ammonium salt to water, mixing and stirring to obtain a solution A; (2) adding a silicon source to solution A, mixing and stirring to obtain solution B; (3) adding the isopropanol solution of the titanium source to solution B, stirring and hydrolyzing to obtain solution C; (4) heating and stirring the solution C in sequence, and crystallizing the solution in a sealed pressure vessel to obtain a crystallized product; (5) The crystallized product is cooled, filtered, washed, dried, and calcined in sequence to obtain the titanium silicate molecular sieve TS-2.

2. The method for preparing titanium silicate molecular sieve TS-2 according to claim 1, characterized in that: In step (1), the quaternary ammonium base is at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide; the quaternary ammonium salt is at least one of quaternary ammonium chloride, quaternary ammonium bromide, quaternary ammonium sulfate, quaternary ammonium phosphate and quaternary ammonium perchlorate; the mixing and stirring is performed at a temperature of 10 to 60° C. and for 5 to 120 minutes.

3. The method for preparing titanium silicate molecular sieve TS-2 according to claim 1, characterized in that: In step (2), the silicon source is at least one of alkyl orthosilicate, silica sol and white carbon black; and the mixing and stirring time is 5 to 120 minutes.

4. The method for preparing titanium silicate molecular sieve TS-2 according to claim 1, characterized in that: In step (3), the titanium source is alkyl titanate; and the stirring and hydrolysis time is 5 to 120 minutes.

5. The method for preparing titanium silicate molecular sieve TS-2 according to claim 1, characterized in that: In steps (1)-(3), the molar ratio of the quaternary ammonium base, quaternary ammonium salt, water, silicon source, titanium source and isopropanol solution is (0.1-0.5):(0.1-0.5):(5-100):1:(0.01-0.05):(0.01-4).

6. The method for preparing titanium silicate molecular sieve TS-2 according to claim 1, characterized in that: In step (4), the temperature of the heating and stirring is 90° C., and the time is 1 to 12 hours; the equipment for the heating and crystallization is a closed container, the temperature is 120 to 180° C., and the time is 12 to 200 hours.

7. The method for preparing titanium silicate molecular sieve TS-2 according to claim 1, characterized in that: In step (5), the washing reagent is deionized water, and the number of times is three times; the drying equipment is a drying oven, the temperature is 80-100° C., to constant weight; the roasting temperature is 550-580° C., and the time is 5-8 hours.

8. Titanium silicate molecular sieve TS-2 prepared by the preparation method according to any one of claims 1 to 7.

9. Use of titanium silicalite TS-2 prepared by the preparation method according to any one of claims 1 to 7 in catalyzing olefin epoxidation, aromatic hydrocarbon hydroxylation and aldehyde ketone ammoxidation.

10. Use of the titanium silicalite TS-2 prepared by the preparation method according to any one of claims 1 to 7 in catalyzing the epoxidation of propylene to produce propylene oxide, catalyzing the hydroxylation of phenol to produce diphenol, and catalyzing the ammoximation of cyclohexanone to produce cyclohexanone oxime.

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