Titanium silicalite molecular sieve, preparation method thereof and application of titanium silicalite molecular sieve in catalyzing oxidation reaction of ethylene sulfite

Abstract

The invention relates to the field of molecular sieve synthesis, and discloses a titanium silicalite molecular sieve, a preparation method thereof, and an application of the titanium silicalite molecular sieve in catalysis of an oxidation reaction of ethylene sulfite. The method comprises the following steps: (1) carrying out first mixing on a silicon dioxide source, an alkali source and water to obtain a mixed solution I; the alkali source is a combination of tetrapropylammonium hydroxide and alkyl glycoside; (2) carrying out second mixing on the mixed solution I and water-soluble cellulose to obtain a mixed solution II; (3) carrying out third mixing on the mixed solution II and a titanium source to obtain a mixed solution III; and (4) crystallizing the mixed solution III, and roasting the obtained solid product to obtain the titanium silicalite molecular sieve. The molar ratio of the silicon dioxide source to the alkali source to the water-soluble cellulose to the titanium source to the water is 1: (0.1-0.5): (0.0001-0.005): (0.01-0.2): (20-100). By adopting the method disclosed by the invention, the titanium silicalite molecular sieve with high ethylene sulfite conversion rate and high ethylene sulfate selectivity can be prepared.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve synthesis, specifically to titanium-silicon molecular sieves, their preparation methods, and their application in the catalytic oxidation of vinyl sulfite. Background Technology

[0002] Titanium silicate molecular sieves have the same MFI-type topology as ZSM-5. Due to the isomorphous substitution of titanium atoms with silicon atoms, titanium silicate molecular sieves have special catalytic activity. Therefore, titanium silicate molecular sieves are widely used in reactions such as epoxidation of olefins, hydroxylation of aromatics, and oxidation of vinyl sulfite.

[0003] Due to the high difficulty and numerous influencing factors in the synthesis of isomorphously substituted titanium atoms, researchers have been seeking inexpensive and stable synthetic methods for titanium-silicon molecular sieves for many years. Currently, the synthesis of titanium-silicon molecular sieves generally employs a hydrothermal synthesis method, often using organosilicon and organotitanium sources. When using inorganic silicon sources, secondary crystallization is often required to further supplement the titanium source and enhance its catalytic activity.

[0004] CN102627293A discloses a method for synthesizing titanium-silicon molecular sieves. This method uses tetraethyl silicate and tetrabutyl titanate as silicon and titanium sources, respectively. After mixing raw materials, hydrolysis, alcohol removal, and hydrothermal crystallization, titanium-silicon molecular sieves can be prepared. Because the synthesis process uses an organosilicon source, an "alcohol removal" process is required to evaporate and remove the ethanol generated during the hydrolysis of the organosilicon source, ensuring that the ethanol does not affect subsequent synthesis processes. The overall process is time-consuming, and the "alcohol removal" process is difficult to control.

[0005] CN103214001A discloses a method for preparing high-performance titanium-silicon molecular sieves. This preparation process first requires the hydrothermal preparation of micron-sized titanium-silicon molecular sieves, followed by alkaline washing, replenishment of the titanium source, and crystallization to finally produce the high-performance titanium-silicon molecular sieve. The synthesis process requires multiple crystallization operations, making it relatively complex and energy-intensive. Summary of the Invention

[0006] The purpose of this invention is to provide a titanium-silicon molecular sieve with high vinyl sulfite conversion rate and high vinyl sulfite selectivity.

[0007] To achieve the above objectives, a first aspect of the present invention provides a method for preparing titanium-silicon molecular sieves, the method comprising: (1) A silica source, an alkali source, and water are mixed to obtain a mixture I; the alkali source is a combination of tetrapropylammonium hydroxide and an alkyl glycoside; (2) Mix the mixture I with water-soluble cellulose to obtain mixture II; (3) Mix the mixture II with the titanium source for a third time to obtain mixture III; (4) The mixture III is crystallized and the resulting solid product is calcined to obtain titanium silicon molecular sieve; The molar ratio of the silica source, the alkali source, the water-soluble cellulose, the titanium source, and the water is 1:0.1-0.5:0.0001-0.005:0.01-0.2:20-100.

[0008] A second aspect of the present invention provides a titanium-silicon molecular sieve prepared by the method described in the first aspect.

[0009] A third aspect of the present invention provides the application of the titanium-silicon molecular sieve described in the second aspect in the catalytic oxidation reaction of vinyl sulfite.

[0010] A fourth aspect of the present invention provides a method for preparing vinyl sulfate, the method comprising: oxidizing vinyl sulfite with hydrogen peroxide in the presence of a catalyst to obtain vinyl sulfate; The catalyst is the titanium-silicon molecular sieve described in the second aspect.

[0011] The method provided by this invention is simple and reproducible, and can omit the "alcohol-driving" process and secondary crystallization process in the traditional titanium-silicon molecular sieve synthesis process. At the same time, the use of silicon dioxide source can greatly reduce costs. The titanium-silicon molecular sieve prepared by the method provided by this invention has high vinyl sulfite conversion rate and high vinyl sulfite selectivity. Attached Figure Description

[0012] Figure 1 These are the XRD patterns of the titanium-silicon molecular sieves prepared in Example 1 and Comparative Examples 1-4 of this invention. Figure 2 These are the XRD patterns of the titanium-silicon molecular sieves prepared in Examples 1-4 of this invention; Figure 3 This is a SEM image of the titanium-silicon molecular sieve prepared in Example 1 of this invention. Detailed Implementation

[0013] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0014] It should be noted that the terms "first," "second," and "third" are merely used to distinguish the reactions at different steps and have no substantive meaning.

[0015] The solvent I, solvent II, and mixture III are simply designated by the numbers "I", "II", and "III" to distinguish the mixtures used in different steps and to avoid confusion; they have no substantive meaning.

[0016] As previously described, a first aspect of the present invention provides a method for preparing titanium-silicon molecular sieves, the method comprising: (1) A silica source, an alkali source, and water are mixed to obtain a mixture I; the alkali source is a combination of tetrapropylammonium hydroxide and an alkyl glycoside; (2) Mix the mixture I with water-soluble cellulose to obtain mixture II; (3) Mix the mixture II with the titanium source for a third time to obtain mixture III; (4) The mixture III is crystallized and the resulting solid product is calcined to obtain titanium silicon molecular sieve; The molar ratio of the silica source, the alkali source, the water-soluble cellulose, the titanium source, and the water is 1:0.1-0.5:0.0001-0.005:0.01-0.2:20-100.

[0017] The method provided by this invention uses a silicon dioxide source, which can greatly reduce costs compared with the traditional synthesis route of titanium-silicon molecular sieves using tetraethyl silicate as the silicon source. It can also avoid the influence of ethanol generated by the hydrolysis of tetraethyl silicate from traditional silicon sources on the synthesis system, and can also omit the "ethanol-driving" process caused by the hydrolysis of a large amount of tetraethyl silicate to generate ethanol.

[0018] The inventors discovered in their research that using a combination of tetrapropylammonium hydroxide and alkyl glycosides as an alkali source has the following effects: (1) Tetrapropylammonium hydroxide can guide the assembly process of the secondary structures formed after the hydrolysis of silica and titanium sources, thereby improving the relative crystallinity of titanium silica molecular sieves; (2) Alkyl glycosides can interact with titanium sources in a timely manner, control the hydrolysis rate of titanium sources within a suitable range, match the hydrolysis process of silica sources, ensure the orderly combination of silicon-oxygen tetrahedra and titanium-oxygen tetrahedra during crystallization, and inhibit the premature aggregation of titanium-oxygen secondary structures; (3) The hydrophobic effect of alkyl groups in alkyl glycosides can inhibit the excessive accumulation of crystal faces during crystallization, and the prepared titanium silica molecular sieves have a loose sheet-like structure.

[0019] Furthermore, water-soluble cellulose can exist stably in an alkaline pH range. After dissolving in water, it forms a cross-linked spatial network structure, which gives the mixture a high viscosity, restricts the flow of water molecules and titanium-silicon secondary structures, and makes the crystallization process more uniform. In addition, the abundant hydroxyl groups and alkyl glycosides in water-soluble cellulose molecules attract each other in aqueous solution, forming intermolecular associations through hydrogen bonds. This interaction with the titanium-oxygen secondary structure can further enhance the dispersion of the titanium-oxygen secondary structure and prevent the titanium-oxygen secondary structure from forming extra-skeleton titanium sites after calcination due to its difficulty in entering the skeleton due to self-polymerization.

[0020] Preferably, the molar ratio of the silica source, the alkali source, the water-soluble cellulose, the titanium source, and the water is 1:0.1-0.3:0.0001-0.004:0.01-0.1:50-100.

[0021] It should be noted that the molar amount of the silica source is measured in terms of the molar amount of silica, excluding any impurities present therein; the molar amount of the water-soluble cellulose is calculated by dividing the mass of the water-soluble cellulose by its number-average molecular weight.

[0022] In a preferred embodiment, in step (1), the molar ratio of the tetrapropylammonium hydroxide to the alkyl glycoside is 1:0.01-0.05. The inventors have found that under these preferred conditions, the prepared titanium silicate molecular sieve exhibits a higher ethylene sulfite conversion rate and a higher ethylene sulfate selectivity.

[0023] Preferably, the tetrapropylammonium hydroxide is provided in the form of a solution; the mass concentration of the tetrapropylammonium hydroxide solution is 20-25%.

[0024] Preferably, the alkyl glycoside is selected from at least one of octyl glucoside, decyl glucoside, lauryl glucoside, tetradecyl glucoside, and hexadecyl glucoside.

[0025] Preferably, in step (1), the silica source is hydrophilic silica and / or hydrophilic nano silica.

[0026] More preferably, the purity of the silicon dioxide source is ≥99%, and the particle size is ≤40nm.

[0027] In this invention, particle size refers to particle diameter. Particles can be regular or irregular in shape; particle diameter refers to the straight-line distance between the two farthest ends.

[0028] In a preferred embodiment, in step (2), the water-soluble cellulose is selected from at least one of hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, and hydroxypropyl methyl cellulose.

[0029] Preferably, the water-soluble cellulose has an average molecular weight of 800-40000. The inventors have discovered that under these preferred conditions, titanium-silicon molecular sieves with higher vinyl sulfite conversion and higher vinyl sulfate selectivity can be obtained.

[0030] In this invention, average molecular weight refers to number-average molecular weight.

[0031] Preferably, the average molecular weight of the water-soluble cellulose is 10,000-40,000; for example, it can be any value between 10,000, 15,000, 20,000, 25,000, 30,000, 35,000, 40,000 or 10,000-40,000.

[0032] In a preferred embodiment, in step (3), the titanium source is tetrabutyl titanate and / or tetrapropyl titanate.

[0033] This invention does not impose special requirements on the specific methods and conditions for the first and second mixing processes, as long as they achieve uniform mixing. Those skilled in the art can use methods known in the art to perform the mixing. This invention will not be described in detail here, and those skilled in the art should not construe this as a limitation of the invention.

[0034] In a preferred embodiment, the specific steps of the third mixing process include: adding the titanium source dropwise to the mixture II under stirring conditions to obtain the mixture III.

[0035] This invention does not have specific requirements for the dropping rate, as long as sufficient reaction is achieved. This invention will not be described in detail here, and those skilled in the art should not interpret this as a limitation of the invention.

[0036] According to a preferred embodiment, in step (4), the crystallization conditions include: a temperature of 150-200°C and a time of 30-192h, preferably 70-150h; for example, it can be any value between 70h, 80h, 90h, 100h, 110h, 120h, 130h, 140h, 150h or 70-150h.

[0037] According to another preferred embodiment, the calcination conditions include: a temperature of 500-650℃ and a time of 4-20h, preferably 4-15h.

[0038] The method described in step (4) of the present invention may further include subjecting the crystallized solid product to conventionally known post-processing methods in the art, such as filtering and drying, before calcining to obtain the titanium-silicon molecular sieve. For example, the crystallized solid product is sequentially filtered, dried at 100-130°C for 6-15 hours, and then calcined to obtain the titanium-silicon molecular sieve.

[0039] As previously stated, a second aspect of the present invention provides a titanium-silicon molecular sieve prepared by the method described in the first aspect.

[0040] As previously stated, a third aspect of the present invention provides the application of the titanium-silicon molecular sieve described in the second aspect in the catalytic oxidation reaction of vinyl sulfite.

[0041] As mentioned above, a fourth aspect of the present invention provides a method for preparing vinyl sulfate, the method comprising: oxidizing vinyl sulfite with hydrogen peroxide in the presence of a catalyst to obtain vinyl sulfate; The catalyst is the titanium-silicon molecular sieve described in the second aspect.

[0042] In a preferred embodiment, the method for preparing vinyl sulfate according to the present invention further includes: crushing the catalyst to a particle size of 5-40 mesh before carrying out the oxidation reaction.

[0043] The present invention does not have special requirements for the crushing method, as long as a catalyst with a particle size of 5-40 mesh is obtained. For example, the titanium-silicon molecular sieve is crushed by compression.

[0044] In this invention, "particle size of 5-40 mesh" refers to passing the material through a 5-mesh Chinese sieve to collect the undersize material and then through a 40-mesh Chinese sieve to collect the oversize material; the Chinese sieve refers to the sieve that complies with the national standards and specifications of China regarding sieves.

[0045] In a preferred embodiment, the molar ratio of the vinyl sulfite to the hydrogen peroxide is 1:1.2-1.4.

[0046] It should be noted that the molar amount of hydrogen peroxide is measured in terms of the molar amount of H2O2, excluding the water present in it.

[0047] Preferably, the hydrogen peroxide has a mass concentration of 25-50%.

[0048] According to a preferred embodiment, the conditions for the oxidation reaction include: a temperature of 50-90°C, a pressure of 0.1-1.0 MPa, and a liquid hourly space velocity of 0.1-20 h⁻¹. -1 Preferably 5-20h -1 For example, it could be 5h. -1 10h -1 15h -1 20h -1 or 5-20h -1 Any value between.

[0049] The present invention will be described in detail below through examples. Unless otherwise specified, specific experimental steps or conditions in the following examples can be performed according to known experimental steps or conditions described in the literature in this field. Unless otherwise specified, the raw materials or instruments used are commercially available. Unless otherwise specified, the reaction temperature in the following examples is at room temperature, which refers to 25±2℃.

[0050] Water-soluble cellulose: Hydroxyethyl cellulose I: average molecular weight 10000; Hydroxypropyl cellulose: average molecular weight 40,000; Hydroxypropyl methylcellulose: average molecular weight 30,000; Hydroxymethyl cellulose: average molecular weight 17,000; Hydroxyethyl cellulose II: average molecular weight 60,000.

[0051] Silica source: Hydrophilic fumed silica: purity 99.9%, particle size ≤40nm; Hydrophilic nano-silica powder: purity 99.9%, particle size ≤40nm.

[0052] Alkali source: Alkali source I: a combination of tetrapropylammonium hydroxide and n-octyl glucoside in a molar ratio of 1:0.01; Alkali source II: a combination of tetrapropylammonium hydroxide and decyl glucoside in a molar ratio of 1:0.036; Alkali source III: a combination of tetrapropylammonium hydroxide and lauryl glucoside in a molar ratio of 1:0.03; Alkali source IV: a combination of tetrapropylammonium hydroxide and hexadecyl glucoside in a molar ratio of 1:0.05; Alkali source V: a combination of tetrapropylammonium hydroxide and n-octyl glucoside in a molar ratio of 1:0.001; The tetrapropylammonium hydroxide used in the above alkaline sources is provided in solution form, and the mass concentration of the tetrapropylammonium hydroxide solution is 25%.

[0053] Hydrogen peroxide: mass concentration of 30%.

[0054] Preparation Example 1 (1) Dissolve alkali source I in deionized water. After the solution is completely dissolved and a clear solution is formed, add 60g of hydrophilic fumed silica and stir until homogeneous to obtain mixture I. (2) Add hydroxyethyl cellulose I to mixture I and stir to obtain mixture II (sol solution); (3) Add tetrabutyl titanate dropwise to mixture II and stir to obtain mixture III (gel solution). (4) Crystallize the mixture III at 170°C for 72 hours, filter the resulting solid, dry it at 120°C for 10 hours, and calcine it at 550°C for 4 hours to obtain titanium silicon molecular sieve I. The molar ratio of hydrophilic fumed silica, alkali source I, hydroxyethyl cellulose I, tetrabutyl titanate, and deionized water is 1:0.2:0.001:0.2:45.

[0055] Preparation Example 2 (1) Dissolve alkali source II in deionized water. After the solution is completely dissolved and a clear solution is formed, add 60g of hydrophilic fumed silica and stir until homogeneous to obtain mixture I. (2) Add hydroxypropyl cellulose to mixture I and stir to obtain mixture II (sol solution); (3) Add tetrapropyl titanate dropwise to mixture II and stir to obtain mixture III (gel solution). (4) Crystallize the mixture III at 190°C for 140 h, and then filter the resulting solid, dry it at 100°C for 15 h, and calcine it at 600°C for 6 h to obtain titanium silicon molecular sieve II. The molar ratio of hydrophilic fumed silica, alkali source II, hydroxypropyl cellulose, tetrapropyl titanate, and deionized water is 1:0.3:0.0007:0.07:75.

[0056] Preparation Example 3 (1) Dissolve alkali source III in deionized water. After the solution is completely dissolved and a clear solution is formed, add 60g of hydrophilic nano silica powder and stir evenly to obtain mixture I. (2) Add hydroxypropyl methylcellulose to mixture I and stir to obtain mixture II (sol solution); (3) Add tetrabutyl titanate dropwise to mixture II and stir to obtain mixture III (gel solution). (4) Crystallize the mixture III at 150°C for 120 h, filter the resulting solid, dry it at 120°C for 6 h, and calcine it at 550°C for 12 h to obtain titanium silicon molecular sieve III. The molar ratio of hydrophilic nano silica powder, alkali source III, hydroxypropyl methylcellulose, tetrabutyl titanate, and deionized water is 1:0.4:0.0005:0.02:50.

[0057] Preparation Example 4 (1) Dissolve the alkali source IV in deionized water. After the solution is completely dissolved and a clear solution is formed, add 60g of hydrophilic nano silica powder and stir evenly to obtain mixture I. (2) Add hydroxymethyl cellulose to mixture I and stir to obtain mixture II (sol solution); (3) Add tetrabutyl titanate dropwise to mixture II and stir to obtain mixture III (gel solution). (4) Crystallize the mixture III at 170°C for 72 hours, filter the resulting solid, dry it at 120°C for 10 hours, and calcine it at 550°C for 4 hours to obtain titanium silicon molecular sieve IV. The molar ratio of hydrophilic nano silica powder, alkali source IV, hydroxymethyl cellulose, tetrabutyl titanate, and deionized water is 1:0.1:0.004:0.04:30.

[0058] Preparation Example 5 The same method as in Preparation Example 1 was used, except that the alkali source I in step (1) was replaced with an equimolar amount of alkali source V to obtain titanium silicon molecular sieve V.

[0059] Preparation Example 6 The same method as in Example 1 was used, except that hydroxyethyl cellulose I in step (2) was replaced with an equimolar amount of hydroxyethyl cellulose II to obtain titanium silicate molecular sieve VI.

[0060] Comparative Preparation Example 1 (1) Dissolve n-octyl glucoside in deionized water. After the solution is completely dissolved and a clear solution is formed, add 60g of hydrophilic fumed silica and stir until homogeneous to obtain mixture I. (2) Add hydroxyethyl cellulose I to mixture I and stir to obtain mixture II (sol solution); (3) Add tetrabutyl titanate dropwise to mixture II and stir to obtain mixture III (gel solution). (4) Crystallize the mixture III at 170°C for 72 hours, filter the resulting solid, dry it at 120°C for 10 hours, and calcine it at 550°C for 4 hours to obtain silicon dioxide DI. The molar ratio of hydrophilic fumed silica, n-octyl glucoside, hydroxyethyl cellulose I, tetrabutyl titanate, and deionized water is 1:0.005:0.001:0.2:45.

[0061] Comparative Preparation Example 2 (1) Dissolve tetrapropylammonium hydroxide solution (mass concentration of 25%) in deionized water. After complete dissolution to form a clear solution, add 60g of hydrophilic fumed silica and stir until homogeneous to obtain mixture I. (2) Add hydroxyethyl cellulose I to mixture I and stir to obtain mixture II (sol solution); (3) Add tetrabutyl titanate dropwise to mixture II and stir to obtain mixture III (gel solution). (4) The mixture III was crystallized at 170°C for 72 hours. The resulting solid was filtered, dried at 120°C for 10 hours, and calcined at 550°C for 4 hours to obtain titanium silicon molecular sieve DII. The molar ratio of hydrophilic fumed silica, tetrapropylammonium hydroxide, hydroxyethyl cellulose I, tetrabutyl titanate, and deionized water is 1:0.2:0.001:0.2:45.

[0062] Comparative preparation example 3 (1) Dissolve alkali source I in deionized water. After the solution is completely dissolved and a clear solution is formed, add 60g of hydrophilic fumed silica and stir until homogeneous to obtain mixture I. (2) Tetrabutyl titanate was added dropwise to mixture I and stirred to obtain mixture II (gel solution); (3) The mixture II was crystallized at 170°C for 72 hours. The resulting solid was filtered, dried at 120°C for 10 hours, and calcined at 550°C for 4 hours to obtain titanium silicon molecular sieve DIII. The molar ratio of hydrophilic fumed silica, alkali source I, tetrabutyl titanate, and deionized water is 1:0.2:0.2:45.

[0063] Comparative preparation example 4 (1) Dissolve alkali source I in deionized water. After the solution is completely dissolved and a clear solution is formed, add 60g of hydrophilic fumed silica and stir until homogeneous to obtain mixture I. (2) Add polypropylene (average molecular weight of 10,000) to mixture I and stir to obtain mixture II (sol solution). (3) Add tetrabutyl titanate dropwise to mixture II and stir to obtain mixture III (gel solution). (4) The mixture III was crystallized at 170°C for 72 hours. The resulting solid was filtered, dried at 120°C for 10 hours, and calcined at 550°C for 4 hours to obtain titanium silicon molecular sieve DIV. The molar ratio of hydrophilic fumed silica, alkali source I, polypropylene, tetrabutyl titanate, and deionized water is 1:0.2:0.001:0.2:45.

[0064] Example 1 Titanium silicate molecular sieve I is crushed into tablets to obtain titanium silicate molecular sieve I with a particle size of 5-40 mesh; then 1.0 g of titanium silicate molecular sieve I is placed in a fixed bed, and a mixed solution of vinyl sulfite and hydrogen peroxide with a molar ratio of 1:1.2 is used as raw material. The raw material is fed into the fixed bed reactor through a micro pump to carry out the oxidation reaction to obtain vinyl sulfate. The oxidation reaction conditions were: temperature 60℃, pressure 0.5 MPa, and liquid hourly space velocity (LISH) 5.0 h⁻¹. -1 .

[0065] Example 2 Titanium silicate molecular sieve II was crushed into tablets to obtain titanium silicate molecular sieve II with a particle size of 5-40 mesh; then 1.0 g of titanium silicate molecular sieve II was placed in a fixed bed, and a mixed solution of vinyl sulfite and hydrogen peroxide with a molar ratio of 1:1.4 was used as raw material. The raw material was fed into the fixed bed reactor through a micro pump to carry out the oxidation reaction to obtain vinyl sulfate. The oxidation reaction conditions were: temperature 70℃, pressure 0.8 MPa, and liquid hourly space velocity (LISH) 10.0 h⁻¹. -1 .

[0066] Example 3 Titanium silicate molecular sieve III was crushed into tablets to obtain titanium silicate molecular sieve III with a particle size of 5-40 mesh; then 1.0 g of titanium silicate molecular sieve III was placed in a fixed bed, and a mixed solution of vinyl sulfite and hydrogen peroxide with a molar ratio of 1:1.3 was used as raw material. The raw material was fed into the fixed bed reactor through a micro pump to carry out the oxidation reaction to obtain vinyl sulfate. The conditions for the oxidation reaction were: temperature 50℃, pressure 0.9 MPa, and liquid hourly space velocity (LISH) 20.0 h⁻¹. -1 .

[0067] Example 4 Titanium silicate molecular sieve IV was crushed into tablets to obtain titanium silicate molecular sieve IV with a particle size of 5-40 mesh; then 1.0 g of titanium silicate molecular sieve IV was placed in a fixed bed, and a mixed solution of vinyl sulfite and hydrogen peroxide with a molar ratio of 1:1.2 was used as raw material. The raw material was fed into the fixed bed reactor through a micro pump to carry out the oxidation reaction to obtain vinyl sulfate. The conditions for the oxidation reaction were: temperature 90℃, pressure 1.0 MPa, and liquid hourly space velocity (LISH) 10.0 h⁻¹. -1 .

[0068] Example 5 The procedure was carried out using a method similar to that in Example 1, except that titanium-silicon molecular sieve I was replaced with an equal mass of titanium-silicon molecular sieve V to obtain ethylene sulfate.

[0069] Example 6 The procedure was carried out using a method similar to that in Example 1, except that titanium-silicon molecular sieve I was replaced with an equal mass of titanium-silicon molecular sieve VI to obtain ethylene sulfate.

[0070] Comparative Example 1 The procedure was carried out using a method similar to that in Example 1, except that titanium silica molecular sieve I was replaced with an equal mass of silica DI to obtain vinyl sulfate.

[0071] Comparative Example 2 The procedure was carried out using a method similar to that in Example 1, except that titanium silicon molecular sieve I was replaced with an equal mass of titanium silicon molecular sieve DII to obtain ethylene sulfate.

[0072] Comparative Example 3 The procedure was carried out using a method similar to that in Example 1, except that titanium-silicon molecular sieve I was replaced with an equal mass of titanium-silicon molecular sieve DIII to obtain vinyl sulfate.

[0073] Comparative Example 4 The procedure was carried out using a method similar to that in Example 1, except that titanium-silicon molecular sieve I was replaced with an equal mass of titanium-silicon molecular sieve DIV to obtain ethylene sulfate.

[0074] Test Example 1 The titanium-silicon molecular sieve prepared in this invention was subjected to the following characterization tests: 1. The present invention provides, by way of example, the XRD patterns of the titanium-silicon molecular sieves prepared in Example 1 and Comparative Examples 1-4, and the XRD patterns of the titanium-silicon molecular sieves prepared in Examples 1-4, as shown below. Figure 1 and Figure 2 As shown in the figure, the titanium-silicon molecular sieve prepared by the method of the present invention has a regular XRD pattern, with high overall intensity and sharp peaks, indicating relatively high crystallinity. Comparative Example 1, without the addition of tetrapropylammonium hydroxide, did not successfully prepare a titanium-silicon molecular sieve, as indicated by the spectrum. The titanium-silicon molecular sieves prepared in other comparative examples have lower peaks, and their relative crystallinity is significantly lower than that of the examples, demonstrating that the components added in the present invention can synergistically promote the crystallization process of the titanium-silicon molecular sieve, promoting the formation of a titanium-silicon molecular sieve with high vinyl sulfite conversion and high vinyl sulfite selectivity.

[0075] 2. The present invention provides, by way of example, SEM images of the titanium-silicon molecular sieve prepared in Example 1, as follows: Figure 3 As shown in the figure, the titanium-silicon molecular sieve obtained in Example 1 has a relatively regular morphology, uniform grain size, smooth surface, and almost no uncrystallized amorphous silicon dioxide and titanium dioxide.

[0076] Test Example 2 The formula for calculating the conversion rate of vinyl sulfite is: (Molar flow rate of vinyl sulfite in raw material - Molar flow rate of vinyl sulfite in product) / Molar flow rate of vinyl sulfite in raw material × 100%.

[0077] The formula for calculating the selectivity of vinyl sulfate is: (Molar flow rate of vinyl sulfate in the product / (Molar flow rate of vinyl sulfite in the feed - Molar flow rate of vinyl sulfite in the product)) × 100%.

[0078] The conversion rate of vinyl sulfite and the selectivity of vinyl sulfate were calculated after 10 hours and 200 hours of reaction, respectively.

[0079] The results are shown in Table 1.

[0080] Table 1

[0081] As can be seen from the results in Table 1, the titanium-silicon molecular sieve prepared by the method provided in this invention has a significantly higher conversion rate of vinyl sulfite and a higher selectivity for vinyl sulfate.

[0082] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing titanium-silicon molecular sieves, characterized in that, The method includes: (1) A silica source, an alkali source, and water are mixed to obtain a mixture I; the alkali source is a combination of tetrapropylammonium hydroxide and an alkyl glycoside. (2) Mix the mixture I with water-soluble cellulose to obtain mixture II; (3) Mix the mixture II with the titanium source for a third time to obtain mixture III; (4) The mixture III is crystallized and the resulting solid product is calcined to obtain titanium silicon molecular sieve; The molar ratio of the silica source, the alkali source, the water-soluble cellulose, the titanium source, and the water is 1:0.1-0.5:0.0001-0.005:0.01-0.2:20-100.

2. The method according to claim 1, characterized in that, In step (1), the molar ratio of the tetrapropylammonium hydroxide and the alkyl glycoside is 1:0.01-0.

05.

3. The method according to claim 2, characterized in that, In step (1), the alkyl glycoside is selected from at least one of octyl glucoside, decyl glucoside, lauryl glucoside, tetradecyl glucoside, and hexadecyl glucoside.

4. The method according to any one of claims 1-3, characterized in that, In step (1), the silica source is hydrophilic silica and / or hydrophilic nano silica; And / or, the purity of the silica source is ≥99%, and the particle size is ≤40nm.

5. The method according to any one of claims 1-3, characterized in that, In step (2), the water-soluble cellulose is selected from at least one of hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, and hydroxypropyl methyl cellulose; And / or, in step (3), the titanium source is tetrabutyl titanate and / or tetrapropyl titanate.

6. The method according to any one of claims 1-3, characterized in that, In step (4), the crystallization conditions include: a temperature of 150-200℃ and a time of 30-192h; And / or, the calcination conditions include: a temperature of 500-650°C and a time of 4-20 hours.

7. The titanium-silicon molecular sieve prepared by the method according to any one of claims 1-6.

8. The application of the titanium-silicon molecular sieve according to claim 7 in the catalytic oxidation reaction of vinyl sulfite.

9. A method for preparing vinyl sulfate, characterized in that, The method includes: oxidizing vinyl sulfite with hydrogen peroxide in the presence of a catalyst to obtain vinyl sulfate; The catalyst is the titanium-silicon molecular sieve as described in claim 7.

10. The method according to claim 9, characterized in that, The molar ratio of the vinyl sulfite to the hydrogen peroxide is 1:1.2-1.4; And / or, the conditions for the oxidation reaction include: a temperature of 20-70°C, a pressure of 0.1-1.0 MPa, and a liquid hourly space velocity of 0.1-20 h⁻¹. -1 .

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