阅读说明：本技术 含锡分子筛及其制备方法和苯酚羟基化反应方法 (Tin-containing molecular sieve, preparation method thereof and phenol hydroxylation reaction method ) 是由 夏长久 林民 朱斌 彭欣欣 舒兴田 于 2019-10-30 设计创作，主要内容包括：本发明涉及分子筛制备领域,具体涉及含锡分子筛及其制备方法和苯酚羟基化反应方法。该分子筛颗粒由粒径为20-50nm的晶粒堆叠而成,所述分子筛颗粒的粒径为100-500nm,所述分子筛颗粒的平均晶界尺寸为2-15nm,晶界介孔体积为0.1-0.8mL/g。本发明提供的含锡分子筛制备方法,可以在较低的模板剂用量和较低的水硅比情况下合成小晶粒堆叠状含锡分子筛材料,可以降低含锡分子筛材料的合成成本,提高合成分子筛晶化产物的固含量,提高单釜分子筛产量。采用本发明提供的含锡分子筛用于苯酚羟基化反应中,具有较高的反应活性和选择性。(The invention relates to the field of molecular sieve preparation, in particular to a tin-containing molecular sieve, a preparation method thereof and a phenol hydroxylation reaction method. The molecular sieve particles are formed by stacking crystal grains with the particle size of 20-50nm, the particle size of the molecular sieve particles is 100-500nm, the average grain boundary size of the molecular sieve particles is 2-15nm, and the mesoporous volume of the grain boundary is 0.1-0.8 mL/g. The preparation method of the tin-containing molecular sieve provided by the invention can synthesize the small-grain stacked tin-containing molecular sieve material under the conditions of lower template agent dosage and lower water-silicon ratio, can reduce the synthesis cost of the tin-containing molecular sieve material, improves the solid content of a crystallized product of the synthesized molecular sieve, and improves the yield of the single-kettle molecular sieve. The tin-containing molecular sieve provided by the invention is used in the phenol hydroxylation reaction, and has higher reaction activity and selectivity.)

1. The tin-containing molecular sieve is characterized in that the molecular sieve particles are formed by stacking crystal grains with the particle size of 20-50nm, the particle size of the molecular sieve particles is 100-500nm, the average grain boundary size of the molecular sieve particles is 2-15nm, and the mesoporous volume of the grain boundary is 0.1-0.8 mL/g.

2. The molecular sieve of claim 1, wherein the molecular sieve has a mole ratio of tin to silicon in the range of 0.005-0.035: 1, preferably 0.01 to 0.03: 1;

preferably, the average grain boundary size of the molecular sieve particles is 5-10nm, and the mesoporous volume of the grain boundary is 0.3-0.5 mL/g.

3. The molecular sieve of claim 1, wherein the molecular sieve is at 25 ℃, P/P₀An adsorbed amount of benzene of at least 70 mg/g, preferably 70 to 80 mg/g, as measured under the condition of an adsorption time of 1 hour, 0.1;

preferably, the molecular sieve has an MFI structure, an MEL structure, a BEA structure, an MWW structure or an MOR structure.

4. A method for preparing a tin-containing molecular sieve, the method comprising:

(1) mixing a tin source, a liquid silicon source, an auxiliary agent and a solvent to obtain a first mixture;

(2) aging the first mixture to obtain an aged sol;

(3) mixing the aged sol, a solid silicon source and a pH regulator to obtain a solid precipitate;

(4) roasting the solid precipitate to obtain tin-silicon oxide;

(5) mixing the tin silicon oxide, the template agent, the seed crystal, water and the inorganic ammonium source to obtain a second mixture, and then crystallizing;

wherein the auxiliary agent comprises a space filler and/or a stabilizer.

5. The production method according to claim 4,

the space filling agent is selected from a silanization reagent and/or a water-soluble high molecular compound;

preferably, the space-filling agent is selected from at least one of a silylating agent, polyacrylamide, and polyacrylic acid;

preferably, the stabilizer is selected from at least one of oxalic acid, t-butyl hydroperoxide, cyclohexyl hydroperoxide, hydrogen peroxide and citric acid;

further preferably, the molar ratio of the auxiliary agent to the liquid silicon source in step (1) is 0.01-0.1: 1, preferably 0.02 to 0.07: 1, wherein the liquid silicon source is SiO₂And (6) counting.

6. The production method according to claim 4, wherein the tin source is selected from at least one of a water-soluble inorganic tin salt, an organic acid salt of tin, and a stannic acid ester;

preferably, the molar ratio of the tin source to the total silicon source used in step (1) is 0.005-0.05: 1, the tin source is SnO₂The total silicon source is SiO₂Counting; the total silicon source is SiO₂Liquid silicon source and SiO₂The sum of the counted solid silicon sources;

preferably, SiO is used in step (1)₂The liquid silicon source and SiO in the step (3)₂The molar ratio of the solid silicon source is 1: 1-9, preferably 1: 2-8;

preferably, the liquid silicon source in step (1) is selected from the group consisting of silicon of the formula Si (OR)¹)₄Of organosilicon esters of, R¹Selected from alkyl groups having 1 to 6 carbon atoms, said alkyl groups being branched or straight chain alkyl groups;

preferably, the solid silicon source in step (3) is silica white and/or silica gel.

7. The production method according to claim 4, wherein the aging conditions in step (2) include: the aging temperature is 20-65 ℃, preferably 20-50 ℃; the aging time is 1 to 60 hours, preferably 2 to 50 hours;

preferably, the roasting conditions in step (4) include: the roasting temperature is 100-500 ℃, and the roasting time is 1-20 hours.

8. The production method according to any one of claims 4 to 7, wherein the templating agent in step (5) comprises an organic quaternary ammonium compound, a long-chain alkyl ammonium compound, and optionally an organic amine;

preferably, the organic quaternary ammonium compound is an organic quaternary ammonium base and/or an organic quaternary ammonium salt;

preferably, the long-chain alkylammonium compound has the formula R²N(R³)₃X, wherein R²Is alkyl with 12-18 carbon atoms, R³Is H or alkyl with 1-4 carbon atoms, and X is monovalent anion;

preferably, the organic amine is one or more of aliphatic amine, alcohol amine and aromatic amine; the fatty amine has a general formula of R⁴(NH₂)_nWherein R is⁴Is an alkyl or alkylene group having 1 to 4 carbon atoms, n ═ 1 or 2; the alcohol amine has the general formula of (HOR)⁵)_mNH_(3-m)Wherein R is⁵Is alkyl having 1 to 4 carbon atoms, m is 1, 2 or 3; the aromatic amine is an amine having one aromatic substituent.

9. The method of claim 8, wherein the molar ratio of the organic quaternary ammonium compound to the total silicon source is from 0.04 to 0.45: 1, the molar ratio of the long-chain alkyl ammonium compound to the total silicon source is 0.04-0.45: 1; the molar ratio of the organic amine to the total silicon source is 0-0.4: 1;

preferably, the molar ratio of the template agent to the total silicon source is 0.08-0.6: 1, preferably 0.1 to 0.3: 1, more preferably 0.1 to 0.25: 1.

10. the production method according to any one of claims 4 to 9, wherein the molar ratio of the water to the total silicon source in step (5) is 5 to 100: 1, preferably 5 to 50: 1, more preferably 6 to 30: 1;

preferably, the molar ratio of the inorganic ammonium source in step (5) to the tin source in step (1) is 0.01-5: 1, preferably 0.02 to 4: 1, more preferably 0.05 to 0.5: 1, the inorganic ammonium source is NH₄ ⁺The tin source is SnO₂Counting;

preferably, in the second mixture in the step (5), the content of the seed crystal is 0.1 to 5% by weight, preferably 1 to 4% by weight, and more preferably 1.5 to 3.5% by weight.

11. The production method according to any one of claims 4 to 10, wherein the crystallization conditions in step (5) include: the crystallization temperature is 110-;

preferably, the crystallization temperature is 140-180 ℃, and more preferably 160-180 ℃;

preferably, the crystallizing comprises: crystallizing at 100-130 deg.C for 0.5-1.5 days, and crystallizing at 160-180 deg.C for 1-3 days.

12. The production method according to any one of claims 4 to 11, wherein the method further comprises a step (6), and the step (6) comprises: mixing the solid product obtained in the step (5), organic alkali and water, and then carrying out second crystallization;

preferably, the conditions of the second crystallization include: the second crystallization temperature is 110-200 ℃, preferably 150-200 ℃; the second crystallization time is 0.5-10 days, preferably 1-8 days;

preferably, the method further comprises drying and calcining the solid product obtained in step (5) and/or the second crystallized product obtained in step (6).

13. A tin-containing molecular sieve prepared by the method of any one of claims 4 to 12.

14. A process for hydroxylating phenol, the process comprising contacting phenol and hydrogen peroxide with a tin-containing molecular sieve under hydroxylation conditions, wherein the tin-containing molecular sieve is as defined in any one of claims 1-3 and 13.

Technical Field

The invention relates to the field of molecular sieve preparation, in particular to a tin-containing molecular sieve, a preparation method thereof and a phenol hydroxylation reaction method.

Background

Heteroatom molecular sieves are newly emerging research hotspots in the chemical and chemical fields in the last three decades, and are also the technological advances of scientific research strived by various countries. Since Taramasso et al in 1983 disclosed that titanium atoms isomorphously substituted framework silicon synthesized TS-1 molecular sieves, the synthesis of titanium-containing microporous or mesoporous molecular sieves has rapidly attracted much attention and invested a great deal of research work, and both the synthesis and application have made good progress, and the industrial production has been realized and the method is successively applied to commercial processes such as phenol hydroxylation, cyclohexanone ammoximation, propylene epoxidation and the like. Following the TS-1 molecular sieve, the tin-containing molecular sieve material (mainly including Sn-MFI and Sn-BEA molecular sieves) is mainly due to the physicochemical properties of tin atoms similar to those of the transition metal titanium. Among the findings of milestone significance are: in 1994, Ramaswamy synthesizes the Sn-MFI molecular sieve by a conventional hydrothermal method for the first time. Professor A.Corma in 2001 finds that the Sn-beta molecular sieve synthesized in a fluorine-containing system can synthesize epsilon-caprolactone in Baeyer-Villiger reaction of cyclohexanone with high selectivity, and can avoid many defects of the traditional organic peroxyacid synthesis route. The M.Davis team of the university of California in 2010 discovers that the Sn-beta molecular sieve has high activity in preparing fructose through catalyzing glucose isomerization, and the materials are considered to successfully simulate the metal activity center of glucose isomerase and break through the influence of temperature, pH value and the like on enzyme catalytic activity. In recent years, people have invested great efforts in the research of tin-silicon molecular sieve materials and have made very good progress.

At present, the synthesis and characterization of tin-silicon molecular sieves still have a large bottleneck, and no commercial production route is developed, because: (1) radius of tin ionGreater than silicon ionLeading tin ions to be difficult to enter the framework of the molecular sieve; (2) in a synthesis system with a higher tin-silicon molar ratio, tin ions delay the nucleation and growth of the molecular sieve to a great extent, so that the tin-silicon molecular sieve has poor crystallinity; (3) for Sn-beta molecular sieves, the BEA structural framework is difficult to form, and a fluorine-containing reagent is usually required to be introduced to cause environmental pollution; (4) the tin source is generally sensitive to a strong alkaline environment and is easy to hydrolyze and self-polymerize; (5) anions contained in the tin source (e.g. Cl)^-Ions) have an effect on the nucleation and growth of molecular sieve crystals. Kangshenghua and the like adopt white carbon black to replace silicone grease and ammonium fluoride to replace hydrofluoric acid, and adopt a dry glue conversion method to synthesize the Sn-beta molecular sieve, but the synthesized molecular sieve has larger size (larger than 2 mu m) and greatly limits the diffusion of a reactant molecular sieve.

The synthesis of Sn-MFI molecular sieves by the dry gel method was first reported by Bokade et al. The authors examined in detail the temperature, time, amount of kettle bottom water, different TPAOH/SiO₂And SiO₂/SnO₂The influence of parameters such as molar ratio on the crystallinity and physicochemical properties of the final sample. The results show that the crystallization temperature, the kettle bottom water amount and the TPAOH/SiO are improved₂And SiO₂/SnO₂The molar ratio can shorten the crystallization time as a whole. In the phenol hydroxylation reaction, the Sn-MFI molecular sieve synthesized by the dry glue method and the Sn-MFI molecular sieve synthesized by the traditional hydrothermal method show equivalent activity.

The tin-silicon molecular sieve synthesized by the existing method mainly takes micropores as main components, and the mesoporous volume is small, so that the mass transfer and diffusion in crystals are not facilitated; and the synthesis difficulty of the molecular sieve is higher.

Disclosure of Invention

The invention aims to solve the problems that the synthesized tin-silicon molecular sieve mainly takes micropores as main components, has small mesoporous volume and has high synthesis difficulty in the prior art, and provides a tin-containing molecular sieve, a preparation method thereof and a phenol hydroxylation reaction method. The preparation method of the tin-containing molecular sieve provided by the invention can save the cost of raw materials and obtain the high-performance small-crystal-grain stacked tin-containing molecular sieve, and the prepared tin-containing molecular sieve has higher oxidation activity and selectivity.

In order to achieve the above object, the first aspect of the present invention provides a tin-containing molecular sieve, wherein the molecular sieve particles are formed by stacking crystal grains with a particle size of 20-50nm, the particle size of the molecular sieve particles is 100-500nm, the average grain boundary size of the molecular sieve particles is 2-15nm, and the grain boundary mesoporous volume is 0.1-0.8 mL/g.

Preferably, the average grain boundary size of the molecular sieve particles is 5-10nm, and the mesoporous volume of the grain boundary is 0.3-0.5 mL/g.

In a second aspect, the present invention provides a method for preparing a tin-containing molecular sieve, the method comprising:

(1) mixing a tin source, a liquid silicon source, an auxiliary agent and a solvent to obtain a first mixture;

(2) aging the first mixture to obtain an aged sol;

(3) mixing the aged sol, a solid silicon source and a pH regulator to obtain a solid precipitate;

(4) roasting the solid precipitate to obtain tin-silicon oxide;

(5) mixing the tin silicon oxide, a template agent, a seed crystal, water and an inorganic ammonium source, and then crystallizing;

wherein the auxiliary agent comprises a space filler and/or a stabilizer.

Preferably, the molar ratio of the tin source to the total silicon source used in step (1) is 0.005-0.05: 1, the tin source is SnO₂The total silicon source is SiO₂Counting; the total silicon source is SiO₂Liquid silicon source and SiO₂The sum of the calculated solid silicon sources.

PreferablyIn the step (1), SiO is used₂The liquid silicon source and SiO in the step (3)₂The molar ratio of the solid silicon source is 1: 1 to 9, more preferably 1: 2-8.

Preferably, the templating agent in step (5) comprises an organic quaternary ammonium compound, a long chain alkyl ammonium compound, and optionally an organic amine.

Preferably, the molar ratio of the template to the total silicon source in step (5) is 0.08-0.6: 1.

preferably, the molar ratio of the water to the total silicon source in step (5) is 5-100: 1.

in a third aspect, the invention provides a tin-containing molecular sieve prepared by the above preparation method.

In a fourth aspect, the present invention provides a phenol hydroxylation reaction method, which includes contacting phenol and hydrogen peroxide with a tin-containing molecular sieve under hydroxylation reaction conditions, wherein the tin-containing molecular sieve is the tin-containing molecular sieve provided by the present invention.

According to the preparation method of the tin-containing molecular sieve, the cheap and easily-obtained solid silicon source is used for partially replacing the expensive liquid silicon source, so that the waste discharge in the production process of the molecular sieve can be reduced, the raw material cost is saved, and meanwhile, the high-performance small-crystal-grain stacked tin-containing molecular sieve material is obtained, and the prepared molecular sieve has higher oxidation activity. The preparation method of the tin-containing molecular sieve provided by the invention can synthesize the small-grain stacked tin-containing molecular sieve material under the conditions of lower template agent dosage and lower water-silicon ratio, can reduce the synthesis cost of the tin-containing molecular sieve material, improves the solid content of a crystallized product of the synthesized molecular sieve, and improves the yield of the single-kettle molecular sieve. The tin-containing molecular sieve prepared by the preparation method provided by the invention is used in phenol hydroxylation reaction, and has higher reaction activity and selectivity.

Drawings

FIG. 1 is an SEM photograph of a Sn-MFI molecular sieve prepared in comparative example 1;

FIG. 2 is a TEM photograph of the Sn-MFI molecular sieve prepared in comparative example 1;

FIG. 3 is an SEM photograph of the Sn-MFI molecular sieve obtained by the rearrangement treatment of comparative example 2;

FIG. 4 is a TEM photograph of the Sn-MFI molecular sieve obtained by the rearrangement treatment of comparative example 2;

FIG. 5 is an SEM photograph of the Sn-MFI molecular sieve prepared in example 1;

FIG. 6 is a TEM photograph of the Sn-MFI molecular sieve prepared in example 1;

FIG. 7 is a TEM photograph of the Sn-MFI molecular sieve obtained from the rearrangement treatment of example 3;

fig. 8 is an XRD spectrum of the tin-containing molecular sieves prepared in example 1, example 2, comparative example 1 and comparative example 2.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The invention provides a tin-containing molecular sieve, wherein the molecular sieve particles are formed by stacking crystal grains with the particle size of 20-50nm, the particle size of the molecular sieve particles is 100-500nm, the average grain boundary size of the molecular sieve particles is 2-15nm, and the mesoporous volume of the grain boundary is 0.1-0.8 mL/g.

According to the invention, the molecular sieve particles of the tin-containing molecular sieve are obtained by stacking crystal grains with the particle size of 20-50nm and detecting through a transmission electron microscope.

According to a preferred embodiment of the present invention, the molar ratio of tin to silicon in the molecular sieve is between 0.005 and 0.035: 1, preferably 0.01 to 0.03: 1.

according to a preferred embodiment of the invention, the grains have an average grain size of 20-50nm, for example 25-46 nm.

According to the invention, the particle size of the molecular sieve particles containing tin molecular sieve and the particle size of the crystal grains are obtained by transmission electron microscope detection (measured by TEM scale).

The molecular sieve particles of the tin-containing molecular sieve provided by the invention contain abundant grain boundaries, and the grain boundaries can strengthen mass transfer diffusion of reactant and product molecules. The average grain boundary size of the molecular sieve particles of the tin-containing molecular sieve provided by the invention is 2-15nm, and the mesoporous volume of the grain boundary is 0.1-0.8 mL/g.

According to a preferred embodiment of the present invention, the molecular sieve particles have an average grain boundary size of 5 to 10nm and a grain boundary mesopore volume of 0.3 to 0.5 mL/g.

According to a preferred embodiment of the present invention, the molecular sieve has a micropore volume of from 0.15 to 0.17 mL/g.

In the present invention, the grain boundaries refer to interfaces between grains having the same structure but different orientations, and the contact interfaces between the grains are called grain boundaries. The grain boundary size refers to the distance between crystal grains, and is obtained by transmission electron microscope detection (measured by a TEM scale).

The tin-containing molecular sieve provided by the invention has a micropore structure and a crystal boundary mesoporous structure, preferably, the pore diameter of micropores is less than 1nm, and the pore diameter (diameter) of mesopores is between 5 and 8 nm. Specifically, the XRD spectrum of the molecular sieve has diffraction peaks at 2 theta angles of 5-35 degrees, which indicates that the molecular sieve has a micropore structure. In the invention, the volume and the pore size distribution of the mesoporous grain boundary are measured by a low-temperature nitrogen adsorption curve method.

According to a preferred embodiment of the invention, the molecular sieve is at 25 ℃ P/P₀The benzene adsorption amount measured under the condition of adsorption time of 1 hour is at least 70 mg/g, preferably 70 to 80 mg/g, 0.1. A hysteresis loop exists between the adsorption isotherm and the desorption isotherm of the low-temperature nitrogen adsorption of the molecular sieve.

According to the present invention, preferably, the molecular sieve has an MFI structure, an MEL structure, a BEA structure, an MWW structure or an MOR structure.

In a second aspect, the present invention provides a method for preparing a tin-containing molecular sieve, the method comprising:

(1) mixing a tin source, a liquid silicon source, an auxiliary agent and a solvent to obtain a first mixture;

(2) aging the first mixture to obtain an aged sol;

(3) mixing the aged sol, a solid silicon source and a pH regulator to obtain a solid precipitate;

(4) roasting the solid precipitate to obtain tin-silicon oxide;

(5) mixing the tin silicon oxide, the template agent, the seed crystal, water and the inorganic ammonium source to obtain a second mixture, and then crystallizing;

wherein the auxiliary agent comprises a space filler and/or a stabilizer.

In the present invention, the space-filling agent is preferably selected from a silylation agent and/or a water-soluble polymer compound, and more preferably a water-soluble polymer. Preferably, the silylating agent is selected from at least one of trimethylchlorosilane, t-butyldimethylchlorosilane, dimethyldiacetoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and di-t-butyldichlorosilane. Preferably, the water-soluble polymer compound is polyacrylamide and/or polyacrylic acid. The weight average molecular weight of the water-soluble polymer compound may be 1000-100000.

In the present invention, preferably, the stabilizer is selected from at least one of oxalic acid, t-butyl hydroperoxide, cyclohexyl hydroperoxide, hydrogen peroxide and citric acid.

According to the present invention, preferably, the molar ratio of the auxiliary agent to the liquid silicon source in step (1) is 0.01-0.1: 1, more preferably 0.02 to 0.07: 1, wherein the liquid silicon source is SiO₂And (6) counting.

Preferably, the molar ratio of the tin source to the total silicon source used in step (1) is 0.005-0.05: 1, more preferably 0.008-0.035: 1, for example, 0.01 to 0.03: 1 or 0.01-0.025: 1 or 0.015 to 0.025: 1, the tin source is SnO₂The total silicon source is SiO₂The total silicon source is SiO₂Liquid silicon source and SiO₂The sum of the calculated solid silicon sources.

Preferably, SiO is used in step (1)₂The liquid silicon source and SiO in the step (3)₂The molar ratio of the solid silicon source is 1: 1-9, more preferably 1: 2-8. In the present invention, the use of high proportions of solid silicon source can reduce the amount of silicon generatedThe production cost can also be increased, and the solid content of the crystallized product of the tin-containing molecular sieve can be increased, so that the yield of single synthesis can be increased under the condition that the synthesis reaction kettle is not changed.

In the present invention, the tin source in the step (1) is not particularly limited. Specifically, the tin source is selected from at least one of water-soluble inorganic tin salt, organic acid salt and stannic acid ester of tin, and is preferably inorganic tin salt.

According to a preferred embodiment of the present invention, the inorganic tin salt is at least one selected from stannous chloride, stannic chloride, stannous nitrate, stannic nitrate, stannous sulfate and stannic sulfate, preferably stannous chloride and/or stannic chloride.

According to a preferred embodiment of the present invention, the organic acid salt of tin is at least one selected from the group consisting of dioctyltin dilaurate, dibutyltin dilaurate and dibutyltin maleate.

According to a preferred embodiment of the invention, the stannate is selected from at least one of tetrabutyl stannate, tetrapropyl stannate, tetraethyl stannate and tetramethyl stannate, preferably tetrabutyl stannate.

In the present invention, the liquid silicon source in the step (1) is not particularly limited. Specifically, the liquid silicon source is selected from at least one of an inorganic liquid silicon source and an organic liquid silicon source, and is preferably an organic liquid silicon source. The inorganic liquid silicon source may be silicon tetrachloride, and preferably, the organic liquid silicon source is selected from silicon tetrachloride with a general formula of Si (OR)¹)₄Of organosilicon esters of, R¹Selected from alkyl groups having 1 to 6, preferably 1 to 4 carbon atoms, said alkyl groups being branched or straight chain alkyl groups.

According to a preferred embodiment of the present invention, the silicone grease is selected from at least one of tetramethylsilicate, tetraethyl silicate, tetrabutyl silicate and dimethyldiethylsilicate; preferably at least one of tetramethyl silicate, tetraethyl silicate and dimethyl diethyl silyl silicate.

In the present invention, the solid silicon source in the step (3) is not particularly limited. In particular, the solid silicon source may be a high purity silicon dioxide solid or powder, preferablyThe solid silicon source is white carbon black and/or high-purity silica gel, and white carbon black is preferred. Preferably, the SiO in the solid silicon source is based on dry weight₂The content is not less than 99.99 weight percent, and the total mass content of Fe, Al and Na impurities is less than 10 ppm; for example SiO₂The content is 99.99 to 100% by weight, and usually more than 99.99 and less than 100% by weight.

According to a specific embodiment of the present invention, SiO is contained in the silica gel₂The content is 99.99 wt.% or more, for example, 99.99 wt.% or more and less than 100 wt.%, and the mass content of Fe, Al and Na impurities is less than 10 ppm.

According to a specific embodiment of the invention, the white carbon black has a specific surface area of 50-400m²The dry basis weight of the white carbon black is taken as a reference, and SiO in the white carbon black₂The content is 99.99 wt.% or more, for example, 99.99 wt.% or more and less than 100 wt.%, and the mass content of Fe, Al and Na impurities is less than 10 ppm.

According to the present invention, the white carbon black can be commercially available or can be prepared according to the existing method, for example, according to the method provided by CN200910227646.2, and the present invention is not particularly limited herein.

In the present invention, the kind and amount of the solvent used in the step (1) are not particularly limited. The tin source, the liquid silicon source and the auxiliary agent are dissolved in the solvent. Specifically, the solvent is selected from water and/or alcohol (preferably alcohol with 1-5C atoms), such as water and/or ethanol.

The specific embodiment of the mixing in step (1) is not particularly limited in the present invention, as long as the tin source, the liquid silicon source, the auxiliary agent and the solvent are uniformly mixed. Preferably, the mixing is carried out under stirring conditions, for example in a magnetic stirrer, for a period of time ranging from 1 to 20 hours.

According to the invention, the aging conditions are selected in a wide range, and preferably, the aging conditions in step (2) include: the aging temperature is 20-65 ℃, preferably 20-50 ℃; the aging time is 1 to 60 hours, preferably 2 to 50 hours, more preferably 3 to 30 hours, for example 3 to 15 hours.

According to a specific embodiment of the present invention, the aging in step (2) refers to allowing the first mixture in step (1) to stand at 20-65 ℃ for 1-60 hours, wherein the aging process preferably does not require stirring, and the first mixture is allowed to stand under the aging conditions.

In the present invention, the pH adjuster in the step (3) is not particularly limited. Specifically, the pH adjuster is at least one selected from the group consisting of an acid, a base, and a salt. Preferably, the pH adjusting agent is selected from hydrochloric acid, ammonia water or sodium carbonate.

The amount of the pH adjusting agent added in the present invention is not particularly limited as long as the solid precipitate (preferably, the aged sol is completely converted into a solid precipitate) is obtained, and those skilled in the art know how to operate based on the above disclosure.

According to a preferred embodiment of the present invention, before the solid precipitate is calcined in step (4), the solid precipitate is filtered and washed. Wherein, the filtration and washing are conventional means well known to those skilled in the art, and the detailed description of the present invention is omitted.

In the present invention, the baking is not particularly limited. Specifically, the roasting conditions in the step (4) include: the roasting temperature is 100-500 ℃, preferably 250-480 ℃, and further preferably 350-450 ℃; the calcination time is 1 to 20 hours, preferably 2 to 10 hours, and more preferably 2 to 8 hours.

In the present invention, the template in the step (5) is not particularly limited. The appropriate template can be selected according to the structure of the desired synthesized molecular sieve (MFI structure, MEL structure, BEA structure, MWW structure or MOR structure). Preferably, the template is selected from at least one of an organic quaternary ammonium compound, a long-chain alkyl ammonium compound and an organic amine, and further preferably, the template comprises the organic quaternary ammonium compound, the long-chain alkyl ammonium compound and optionally the organic amine.

Preferably, the organic quaternary ammonium compound is an organic quaternary ammonium base and/or an organic quaternary ammonium salt. Further preferably, the organic quaternary ammonium base is selected from at least one of tetrapropylammonium hydroxide, tetrabutylammonium hydroxide and tetraethylammonium hydroxide, and the organic quaternary ammonium salt is selected from at least one of tetrapropylammonium bromide, tetrabutylammonium bromide, tetraethylammonium bromide, tetrapropylammonium chloride, tetrabutylammonium chloride and tetraethylammonium chloride.

According to a preferred embodiment of the present invention, the tin-containing molecular sieve obtained by the preparation method has an MFI structure, and the organic quaternary ammonium compound is at least one selected from the group consisting of tetrapropylammonium hydroxide, tetrapropylammonium chloride and tetrapropylammonium bromide.

According to a preferred embodiment of the present invention, the tin-containing molecular sieve obtained by the preparation method has a MEL structure, and the organic quaternary ammonium compound is at least one selected from tetrabutylammonium hydroxide, tetrabutylammonium bromide and tetrabutylammonium chloride.

According to a preferred embodiment of the present invention, the tin-containing molecular sieve obtained by the preparation method has a BEA structure, and the organic quaternary ammonium compound is at least one selected from tetraethylammonium hydroxide, tetraethylammonium bromide and tetraethylammonium chloride.

Preferably, the long-chain alkylammonium compound has the formula R²N(R³)₃X, wherein R²Is alkyl with 12-18 carbon atoms, R³Is H or an alkyl radical having 1 to 4 carbon atoms, X is a monovalent anion, for example OH^-、Cl^-、Br^-. Specifically, when X is OH^-When the long-chain alkyl ammonium compound is a basic long-chain alkyl ammonium compound; when X is Cl^-When the long-chain alkyl ammonium compound is long-chain alkyl ammonium chloride; when X is Br^-When the alkyl ammonium compound is a long-chain alkyl ammonium bromide compound, the long-chain alkyl ammonium bromide compound is a long-chain alkyl ammonium bromide compound.

According to a preferred embodiment of the present invention, the basic long-chain alkylammonium compound is selected from at least one of dodecyltrimethylammonium hydroxide, tetradecyltrimethylammonium hydroxide, hexadecyltrimethylammonium hydroxide and octadecyltrimethylammonium hydroxide.

According to a preferred embodiment of the invention, the long-chain alkyl ammonium chloride is selected from at least one of dodecyl ammonium chloride, tetradecyl ammonium chloride, hexadecyl ammonium chloride and octadecyl ammonium chloride.

According to a preferred embodiment of the invention, the long chain alkyl ammonium bromide is selected from at least one of dodecyl trimethyl ammonium bromide, tetradecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium bromide and octadecyl trimethyl ammonium bromide.

According to the present invention, preferably, the organic amine is at least one of an aliphatic amine, an alcohol amine, and an aromatic amine; the fatty amine has a general formula of R⁴(NH₂)_nWherein R is⁴Is an alkyl or alkylene group having 1 to 4 carbon atoms, n ═ 1 or 2; the alcohol amine has the general formula of (HOR)⁵)_mNH_(3-m)Wherein R is⁵Is alkyl having 1 to 4 carbon atoms, m is 1, 2 or 3; the aromatic amine is an amine having one aromatic substituent.

According to a preferred embodiment of the present invention, the aliphatic amine is at least one selected from the group consisting of ethylamine, n-butylamine, butanediamine and hexamethylenediamine.

According to a preferred embodiment of the present invention, the alcohol amine is at least one selected from the group consisting of monoethanolamine, diethanolamine and triethanolamine.

According to a preferred embodiment of the present invention, the aromatic amine is at least one selected from aniline, toluidine and p-phenylenediamine.

According to the present invention, preferably, the molar ratio of the organic quaternary ammonium compound to the total silicon source is 0.04-0.45: 1, the molar ratio of the long-chain alkyl ammonium compound to the total silicon source is 0.04-0.45: 1; the molar ratio of the organic amine to the total silicon source is 0-0.4: 1.

preferably, the molar ratio of the template agent to the total silicon source is 0.08-0.6: 1, preferably 0.1 to 0.3: 1, more preferably 0.1 to 0.25: 1.

according to the present invention, preferably, the molar ratio of the water to the total silicon source in step (5) is 5 to 100: 1. in the method provided by the invention, the small-grain stacked tin-containing molecular sieve can be synthesized at high solid content, so that the using amount of water is reduced, the single-kettle yield is improved, namely more molecular sieves are synthesized under the same synthesis reactor volume, and the molar ratio of the water to the total silicon source in the step (5) is preferably 5-80: 1 or 5-50: 1 or 6-30: 1 or 6-20: 1 or 6-15: 1.

preferably, the molar ratio of the inorganic ammonium source in step (5) to the tin source in step (1) is 0.01-5: 1, preferably 0.02 to 4: 1, more preferably 0.05 to 0.5: 1, the inorganic ammonium source is NH₄ ⁺The tin source is SnO₂And (6) counting.

In the present invention, the inorganic ammonium source in the step (5) is not particularly limited. In particular, the inorganic ammonium source is selected from inorganic ammonium salts and/or aqueous ammonia, preferably aqueous ammonia. The inorganic ammonium salt is preferably at least one selected from the group consisting of ammonium chloride, ammonium nitrate and ammonium sulfate.

In the invention, the inorganic ammonium source is added, so that the oxidation activity of the tin-containing molecular sieve is improved, the utilization rate of the tin source (higher framework tin-silicon ratio under the condition of the same tin source usage) is improved, and the usage amount of the tin source is reduced.

According to a preferred embodiment of the present invention, in the second mixture in the step (5), the content of the seed crystal is 0.1 to 5% by weight, preferably 1 to 4% by weight, and more preferably 1.5 to 3.5% by weight.

In the present invention, the kind of the seed crystal in the step (5) is not particularly limited, and may be various seed crystals conventionally used in the art. One skilled in the art will be able to select appropriate seeds depending on the structure of the molecular sieve being synthesized. The seed crystals may be synthesized according to conventional techniques in the art.

In the present invention, the crystallization is not particularly limited. Preferably, the crystallization conditions in step (5) include: the crystallization temperature is 110-200 ℃, preferably 140-180 ℃, and further preferably 160-180 ℃; the crystallization pressure is autogenous pressure, and the crystallization time is 2 to 480 hours, preferably 0.5 to 10 days, for example, 1 to 6 days, and more preferably 1 to 3 days.

According to one embodiment of the invention, the crystallization may be carried out in a stainless steel stirred tank. The temperature rise for crystallization can be carried out in a one-stage temperature rise manner or a multi-stage temperature rise manner, and the temperature rise rate can be carried out according to the existing crystallization temperature rise method, for example, 0.5-1 ℃/min.

According to a preferred embodiment of the present invention, the crystallization conditions include: crystallizing at 100-.

According to the present invention, a liquid silicon source may also optionally be added in step (5). The selection of the kind of the liquid silicon source is as described above, and will not be described herein again. According to a preferred embodiment of the present invention, the step (5) comprises: and mixing the tin-silicon oxide, the template agent, the seed crystal, water, the inorganic ammonium source and the liquid silicon source to obtain a second mixture, and then crystallizing. Wherein SiO is used in the step (5)₂The liquid silicon source and SiO in the step (1) are counted₂The molar ratio of the liquid silicon source is 0.1-10: 1.

according to an embodiment of the present invention, if a liquid silicon source is further added in step (5), the liquid silicon source added in step (5) is counted as the liquid silicon source in the total silicon source. That is, in this case, the liquid silicon source in the total silicon source includes the liquid silicon source introduced in step (1) and step (5).

According to the invention, the method can also comprise recovering the tin-containing molecular sieve from the product obtained by crystallization in the step (5). The method for recovering the tin-containing molecular sieve can be an existing method and comprises the steps of filtering, washing and roasting a crystallized product or filtering, washing, drying and roasting the crystallized product. The purpose of filtration is to separate the crystallized small-grain stacked tin-containing molecular sieve from the crystallization mother liquor, and the purpose of washing is to wash off the silicon-containing template adsorbed on the surface of the molecular sieve particles, and for example, the molecular sieve and water can be mixed and washed at the temperature of room temperature to 50 ℃ and the weight ratio of the molecular sieve to the water of 1 (1-20) such as 1 (1-15) and then filtered or rinsed with water. The drying is to remove most of the water in the molecular sieve to reduce the water evaporation amount during calcination, and the drying temperature can be 100-200 ℃. The purpose of calcination is to remove the template in the molecular sieve, for example, the calcination temperature is 350-650 ℃, and the calcination time is 2-10 hours. The tin-containing molecular sieve provided by the invention is obtained by recovery.

According to the invention, preferably, the method further comprises a step (6), said step (6) comprising: and (4) mixing the solid product obtained in the step (5), organic base and water, and then carrying out second crystallization.

Preferably, the conditions of the second crystallization include: the second crystallization temperature is 110-200 ℃, more preferably 150-200 ℃; the second crystallization time is 0.5 to 10 days, more preferably 1 to 8 days.

According to a preferred embodiment of the present invention, the solid product obtained in step (5), an organic base and water are mixed and subjected to a second crystallization. The obtained small crystal grain stacked tin-containing molecular sieve has a hollow structure, and the molecular sieve rearrangement is called in the invention. Preferably, the organic base is reacted with the solid product obtained in step (5) (in SiO)₂In terms of) is 0.02 to 0.5: 1, more preferably 0.02 to 0.2: 1. preferably, the water is mixed with the solid product (in SiO)₂In terms of) in a molar ratio of 2 to 50: 1, more preferably 2 to 30: 1, for example 2 to 20: 1, preferably 5 to 10: 1. the organic base may be organic amine and/or organic quaternary ammonium base, and the organic amine and the organic quaternary ammonium base are defined as above, which is not described herein again.

Specifically, the method can also comprise recovering the tin-containing molecular sieve from the product obtained by crystallization in the step (6). Generally comprises filtering, washing, drying and then roasting the crystallized product, and the recovery method can be referred to the step (5), and the invention is not described herein.

In the present invention, the rearrangement of the molecular sieve step (6) may be performed once or may be repeated a plurality of times. The rearranged tin-containing molecular sieve with more obvious mesoporous structure and stacked small crystal grains is obtained through rearrangement treatment, and the rearranged tin-containing molecular sieve has larger pore volume and specific surface area.

In a third aspect, the invention provides a tin-containing molecular sieve prepared by the preparation method.

In a fourth aspect, the present invention provides a phenol hydroxylation reaction method, which includes contacting phenol and hydrogen peroxide with a tin-containing molecular sieve under hydroxylation reaction conditions, wherein the tin-containing molecular sieve is the tin-containing molecular sieve provided by the present invention.

The hydroxylation reaction method of the present invention is not particularly limited in its reaction conditions, and may be carried out under conventional conditions. Specifically, the hydroxylation reaction conditions comprise: the reaction temperature is 40-120 ℃, preferably 50-100 ℃, the reaction pressure is 0-5MPa, preferably 0.1-3MPa, and the reaction time is 0.5-5h, preferably 0.1-3 h.

In general, the molar ratio of phenol to hydrogen peroxide may be 1: 0.1 to 10, preferably 1: 0.2 to 5, more preferably 1: 0.3-1.

The contacting may be carried out in a solvent or in the absence of a solvent. The solvent may be one or more of alcohol, ketone, nitrile, ether, ester and water. Specific examples of the solvent may include, but are not limited to, at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, acetone, butanone, methyl t-butyl ether, acetonitrile, and water. Preferably, the solvent is at least one of methanol, acetone and water. The amount of the solvent used in the present invention is not particularly limited, and may be selected conventionally. Generally, the solvent may be used in an amount of 10 to 5000 parts by weight, preferably 50 to 4000 parts by weight, and more preferably 50 to 2000 parts by weight, relative to 100 parts by weight of phenol.

The present invention will be described in detail below by way of examples.

SEM electron microscope experiments were performed on Hitachi S4800 high resolution cold field emission scanning electron microscope.

TEM electron microscopy experiments were carried out on a transmission electron microscope of the type Tecnai F20G 2S-TWIN, from FEI, equipped with an energy filtration system GIF2001 from Gatan, with an attached X-ray energy spectrometer. The electron microscope sample is prepared on a micro-grid with the diameter of 3mm by adopting a suspension dispersion method.

XRD measurement method: x-ray diffraction (XRD) crystallography of the sample was performed on a Siemens D5005X-ray diffractometer using a CuK alpha radiation sourceTube voltage40kV, tube current 40mA, scanning speed 0.5 degree/min, and scanning range 2 theta 4-40 degrees.

The characterization method of the low-temperature nitrogen adsorption curve was performed on a Micromeritics ASAP-2010 static nitrogen adsorption apparatus manufactured by Quantachrome.

The pore volume was measured by a nitrogen adsorption capacity method according to the BJH calculation method (see petrochemical analysis method (RIPP test method), RIPP151-90, scientific Press, 1990).

The particle size of the molecular sieve particles containing tin molecular sieve and the particle size of the crystal grains were determined by transmission electron microscopy (as measured on a TEM scale).

In the following examples, room temperature was 25 ℃ unless otherwise specified.

The seed crystals were prepared according to the methods described in the literature (Mal N K, Ramasumamy V, Rajamohanan P R, et al. Sn-MFI molecular dimensions: synthesis methods, Si liquid and liquid MAS-NMR, Sn static and MAS NMR students [ J ]. Microporous Materials,1997,12(4-6): 331-340.).

The sources of the raw materials used in the examples and comparative examples are as follows:

tetrabutyl stannate, analytically pure, chemical reagents of national drug group, ltd.

Tin tetrachloride, analytically pure, chemical reagents of the national drug group, ltd.

Tetrapropylammonium hydroxide, available from Guangdong chemical plant.

Tetraethyl silicate, analytically pure, chemical reagents of the national pharmaceutical group, ltd.

Ammonia, analytically pure, concentration 20% by weight.

White carbon black, Zhejiang Juhua group product, model AS-150; the solid content is more than 95 wt%, the silicon dioxide content in dry basis is more than 99.99 wt%, the total content of Fe, Al and Na is less than 10ppm, and the specific surface area is 195m²/g。

Other reagents are not further described, and are all commercial products and analytically pure.

The gas chromatograph is a model 6890 gas chromatograph produced by Agilent company; the analytical chromatographic column used was a FFAP column.

The conversion rate of phenol and the selectivity of benzenediol in the test examples are respectively calculated according to the following formulas:

the molar selectivity of benzenediol/(the molar amount of phenol charged before the reaction-the molar amount of phenol remaining after the reaction)% 100%.

Comparative example 1

Mixing 22.5g tetraethyl silicate with 7g tetrapropylammonium hydroxide, adding 59.8g deionized water, and uniformly mixing; then hydrolyzing for 1h at 60 ℃ to obtain a hydrolysis solution of tetraethyl silicate. Under vigorous stirring, a solution of 1.1g of tin tetrachloride pentahydrate and 5g of isopropanol was slowly added dropwise to the above solution, and the mixture was stirred at 75 ℃ for 3 hours to give a clear and transparent colloid. And then the colloid is transferred into a stainless steel closed reaction kettle and crystallized for 3 days at the constant temperature of 170 ℃, thus obtaining the conventional tin-containing molecular sieve D-1.

SEM and TEM photographs of the tin-containing molecular sieve D-1 are shown in figures 1 and 2, and an XRD analysis spectrum is shown in figure 8. The average particle size of the molecular sieve grains, the average particle size of the molecular sieve particles, and the average grain boundary size are shown in table 2. The micropore volume, mesopore volume and benzene adsorption amount of the molecular sieve are shown in table 2.

Comparative example 2

Mixing 22.5g tetraethyl silicate with 9g tetrapropyl ammonium hydroxide, adding 64.5g deionized water, and uniformly mixing; then hydrolyzing for 1h at 60 ℃ to obtain a hydrolysis solution of tetraethyl silicate. Under vigorous stirring, a solution of 0.6g of tin tetrachloride pentahydrate and 7g of isopropanol was slowly added dropwise to the above solution, and the mixture was stirred at 75 ℃ for 7 hours to give a clear and transparent colloid. And then the colloid is transferred into a stainless steel closed reaction kettle and crystallized for 3 days at the constant temperature of 170 ℃ to obtain the conventional tin-containing molecular sieve.

Then mixing stannic chloride, anhydrous isopropanol, tetrapropylammonium hydroxide and deionized water according to the proportion of 1: 15: 2.4: 350, and hydrolyzing for 30 minutes at 45 ℃ under normal pressure to obtain a hydrolyzed solution of stannic chloride. Taking the prepared tin-containing molecular sieve, and preparing the tin-containing molecular sieve according to the following molecular sieve (g): sn (mol) ═ 600: 1, uniformly mixing with the hydrolysis solution of the stannic chloride, uniformly stirring for 12 hours at normal temperature (25 ℃), finally putting the dispersed suspension into a stainless steel reaction kettle, and standing for 3 days at 165 ℃ to obtain the rearranged stannic molecular sieve D-2.

SEM and TEM photographs of the tin-containing molecular sieve D-2 are shown in figures 3 and 4, and an XRD analysis spectrum is shown in figure 8. The average particle size of the molecular sieve grains, the average particle size of the molecular sieve particles, and the average grain boundary size are shown in table 2. The micropore volume, mesopore volume and benzene adsorption amount of the molecular sieve are shown in table 2.

Examples 1 to 12 of the present invention are made of SiO₂The total silicon source usage was fixed at 0.2 mol.

Example 1

(1) SnCl₂·2H₂O, tetraethyl silicate (TEOS), polyacrylic acid (weight average molecular weight 5000) powder and 3g of water were sequentially added to a 500mL beaker, placed on a magnetic stirrer with heating and stirring functions, mixed uniformly, and stirred at room temperature for 4 hours to obtain a first mixture.

(2) And standing the first mixture at room temperature for 12 hours for aging treatment to obtain an aged sol.

(3) Adding white carbon black powder into the aged sol under stirring, adding 8 wt% ammonium carbonate solution, and manually stirring to form a white viscous solid precipitate.

(4) Washing the solid precipitate with deionized water for 3 times, and roasting in a 400 ℃ muffle furnace for 6 hours to obtain SnO₂-SiO₂White oxide.

(5) Mixing the tin silicon oxide, 25.05 weight percent tetrapropylammonium hydroxide aqueous solution (TPAOH), hexadecyltrimethylammonium hydroxide (MSDS), 20 weight percent ammonia water, seed crystals and water to obtain a second mixture, then transferring the second mixture into a stainless steel closed reaction kettle, crystallizing the second mixture at a constant temperature of 175 ℃ for 48 hours to obtain a crystallized sample, filtering and washing the crystallized sample, drying the crystallized sample at 120 ℃ for 24 hours, and roasting the crystallized sample at 550 ℃ for 6 hours to obtain the small-grain stacked tin-containing molecular sieve S-1 with an MFI structure.

SEM and TEM photographs of the tin-containing molecular sieve S-1 are shown in figures 5 and 6, and an XRD analysis spectrum is shown in figure 8.

As can be seen from fig. 5 and 6, the molecular sieve particles are stacked with grains having a diameter of 20 to 50 nm. The average particle size of the molecular sieve grains, the average particle size of the molecular sieve particles, and the average grain boundary size are shown in Table 2. The micropore volume, mesopore volume and benzene adsorption amount of the molecular sieve are shown in table 2.

Example 2

(1) Tetrabutyl stannate, silicon tetrachloride, tert-butyl hydroperoxide and 10g of ethanol are sequentially added into a 500mL beaker, put on a magnetic stirrer with heating and stirring functions, mixed uniformly and stirred at room temperature for 10 hours to obtain a first mixture.

(2) And standing the first mixture at 37 ℃ for 24 hours for aging treatment to obtain an aged sol.

(3) Adding white carbon black powder into the aged sol under stirring, adding an ammonia water solution with the concentration of 15 wt%, and manually stirring to form a white viscous solid precipitate.

(4) Washing the solid precipitate with deionized water for 3 times, and roasting in a muffle furnace at 450 ℃ for 4 hours to obtain SnO₂-SiO₂White oxide.

(5) Mixing the tin silicon oxide, 25.05 wt% of tetrapropylammonium hydroxide aqueous solution (TPAOH), hexadecyltrimethylammonium hydroxide (MSDS), 20 wt% of ammonia water, seed crystals and water to obtain a second mixture, then transferring the second mixture into a stainless steel closed reaction kettle, crystallizing the second mixture at a constant temperature of 160 ℃ for 48 hours to obtain a crystallized sample, filtering and washing the crystallized sample, drying the crystallized sample at 120 ℃ for 24 hours, and roasting the crystallized sample at 550 ℃ for 6 hours to obtain the small-grain stacked tin-containing molecular sieve S-2 with an MFI structure.

The SEM image and TEM image of the tin-containing molecular sieve S-2 are similar to those of the tin-containing molecular sieve S-1, and the XRD analysis spectrum is shown in FIG. 8.

The average particle size of the molecular sieve grains, the average particle size of the molecular sieve particles, and the average grain boundary size are shown in table 2. The micropore volume, mesopore volume and benzene adsorption amount of the molecular sieve are shown in table 2.

Example 3

Taking the tin-containing molecular sieve S-2 prepared in example 2 as a matrix, mixing 6g of the sample with 22.05 weight percent of TPAOH aqueous solution, uniformly stirring, crystallizing at 150 ℃ for 3 days in a closed reaction kettle, filtering, washing, drying at 120 ℃ for 24 hours, and roasting at 550 ℃ for 6 hours to obtain the tin-containing molecular sieve S-3 with hollow small crystal grain stacking shape, wherein the tin-containing molecular sieve S-3 has an MFI structure.

The TEM photograph of the tin-containing molecular sieve S-3 is shown in FIG. 7. The average particle size of the molecular sieve grains, the average particle size of the molecular sieve particles, and the average grain boundary size are shown in table 2. The micropore volume, mesopore volume and benzene adsorption amount of the molecular sieve are shown in table 2.

Examples 4 to 7

Tin-containing molecular sieves were prepared according to the method of example 1, and the components and synthesis conditions of the tin-containing molecular sieves are shown in table 1, to obtain small-grained stacked tin-containing molecular sieves S-4 to S-7. The average particle size of the molecular sieve grains, the average particle size of the molecular sieve particles, and the average grain boundary size are shown in table 2. The micropore volume, mesopore volume and benzene adsorption amount of the molecular sieve are shown in table 2.

Example 8

A tin-containing molecular sieve was prepared by following the procedure of example 1, except that in the step (5), first, crystallization was carried out at 120 ℃ for 1 day, and then crystallization was carried out at 170 ℃ for 2 days, and the composition and synthesis conditions of the tin-containing molecular sieve are shown in Table 1, to obtain a tin-containing molecular sieve S-8 in a small-grained stacked state. The average particle size of the molecular sieve grains, the average particle size of the molecular sieve particles, and the average grain boundary size are shown in table 2. The micropore volume, mesopore volume and benzene adsorption amount of the molecular sieve are shown in table 2.

Example 9

A tin-containing molecular sieve having a MEL structure is prepared. Referring to the method according to example 1, the tin-containing molecular sieve S-9 in a small grain stacked state was obtained by changing the compounding ratio and the template, the components of the tin-containing molecular sieve and the synthesis conditions are shown in table 1. The average particle size of the molecular sieve grains, the average particle size of the molecular sieve particles, and the average grain boundary size are shown in table 2. The micropore volume, mesopore volume and benzene adsorption amount of the molecular sieve are shown in table 2.

Example 10

Preparing the tin-containing molecular sieve with the BEA structure. Referring to the method of example 1, the tin-containing molecular sieve S-10 was obtained in a small-grained stacked state by changing the compounding ratio and the template, and the tin-containing molecular sieve components and the synthesis conditions thereof are shown in Table 1. The average particle size of the molecular sieve grains, the average particle size of the molecular sieve particles, and the average grain boundary size are shown in table 2. The micropore volume, mesopore volume and benzene adsorption amount of the molecular sieve are shown in table 2.

Example 11

The procedure of example 1 was followed except that the aging temperature was 85 ℃ and the crystallization temperature in step (5) was 110 ℃ to obtain tin-containing molecular sieve S-11. The average particle size of the molecular sieve grains, the average particle size of the molecular sieve particles, and the average grain boundary size are shown in table 2. The micropore volume, mesopore volume and benzene adsorption amount of the molecular sieve are shown in table 2.

Example 12

The procedure of example 1 was followed, except that polyacrylic acid was replaced with an equimolar amount of trimethylchlorosilane, to obtain a tin-containing molecular sieve S-12. The average particle size of the molecular sieve grains, the average particle size of the molecular sieve particles, and the average grain boundary size are shown in table 2. The micropore volume, mesopore volume and benzene adsorption amount of the molecular sieve are shown in table 2.

Comparative example 3

Following the procedure of example 1, except that no auxiliary agent was added, tin-containing molecular sieve D-3 was obtained. The average particle size of the molecular sieve grains, the average particle size of the molecular sieve particles, and the average grain boundary size are shown in table 2. The micropore volume, mesopore volume and benzene adsorption amount of the molecular sieve are shown in table 2.

Comparative example 4

Following the procedure of example 1, except that no adjuvant was added and no aging was performed, tin-containing molecular sieve D-4 was obtained. The average particle size of the molecular sieve grains, the average particle size of the molecular sieve particles, and the average grain boundary size are shown in table 2. The micropore volume, mesopore volume and benzene adsorption amount of the molecular sieve are shown in table 2.

Comparative example 5

The procedure of example 1 was followed, except that the solid silicon source in step (3) was added to step (1), to obtain tin-containing molecular sieve D-5. The average particle size of the molecular sieve grains, the average particle size of the molecular sieve particles, and the average grain boundary size are shown in table 2. The micropore volume, mesopore volume and benzene adsorption amount of the molecular sieve are shown in table 2.

Test example

The tin-containing molecular sieves prepared in the above examples 1 to 12 and comparative examples 1 to 5 were used as catalysts for phenol hydroxylation reactions to carry out the phenol hydroxylation reactions.

1.25g of the tin-containing molecular sieves prepared in examples 1 to 12 and comparative examples 1 to 5 above were respectively put into a three-necked flask reaction vessel containing 25g of phenol and 20mL of acetone, and after the temperature stabilized to 80 ℃, hydrogen peroxide having a concentration of 30% by weight, phenol: hydrogen peroxide (with H)₂O₂In terms of) is 1: 0.3, sampling after reacting for 2 hours at the temperature of 80 ℃ and the pressure of 0.1MPa, carrying out quantitative analysis on the concentration of each substance after the reaction by using a gas chromatograph, and calculating the conversion rate of phenol, the selectivity of catechol and the selectivity of hydroquinone, wherein specific results are shown in a table 2.

From the data in table 2, it can be seen that the tin-containing molecular sieve of the present invention has a smaller grain size, a larger mesoporous volume and a larger benzene adsorption amount than the existing tin-containing molecular sieve. The tin-containing molecular sieve provided by the invention is used as a catalyst for phenol hydroxylation reaction, and can obtain more excellent catalytic performance.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.