阅读说明：本技术 含钛分子筛及其制备方法和苯酚羟基化反应方法 (Titanium-containing molecular sieve, preparation method thereof and phenol hydroxylation reaction method ) 是由 夏长久 彭欣欣 林民 朱斌 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,具体涉及含钛分子筛及其制备方法和苯酚羟基化反应方法。所述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4-15nm,晶界介孔体积为0.2-0.8mL/g。本发明提供的含钛分子筛制备方法,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钛分子筛材料,可以降低含钛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钛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 titanium-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 4-15nm, and the mesoporous volume of the grain boundary is 0.2-0.8 mL/g. The preparation method of the titanium-containing molecular sieve provided by the invention can synthesize the small-grain stacked titanium-containing molecular sieve material under the conditions of lower template agent dosage and lower water-silicon ratio, can reduce the synthesis cost of the titanium-containing molecular sieve material, improves the solid content of the synthesized molecular sieve crystallized product, and improves the yield of the single-kettle molecular sieve. The titanium-containing molecular sieve provided by the invention is used in the phenol hydroxylation reaction, and has higher reaction activity and selectivity.)

1. The titanium-containing molecular sieve is characterized in that 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 4-15nm, and the mesoporous volume of the grain boundary is 0.2-0.8 mL/g.

2. The molecular sieve of claim 1, wherein the molar ratio of titanium to silicon in the molecular sieve is from 0.005 to 0.04: 1, preferably 0.02-0.035: 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/P₀(ii) an adsorbed benzene amount of at least 70 mg/g as measured at 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 titanium-containing molecular sieve, the method comprising:

(1) mixing a titanium 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 titanium silicon oxide;

(5) mixing the titanium silicon oxide, the template agent, the seed crystal and/or the titanium silicon molecular sieve precursor, water and an 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 titanium source is selected from at least one of a water-soluble inorganic titanium salt and a titanate;

preferably, the molar ratio of the titanium source to the total silicon source used in step (1) is 0.005-0.05: 1, the titanium source is TiO₂The 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 25-50 ℃; 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 0.2: 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 titanium source in step (1) is from 0.01 to 5: 1, preferably 0.01 to 4: 1, more preferably 0.01 to 0.5: 1, the inorganic ammonium source is NH₄ ⁺The titanium source is calculated as TiO₂Counting;

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

preferably, the molar ratio of the titanium silicalite precursor in step (5) to the titanium silicalite oxide in step (4) is 0-1: 1, preferably 0.01 to 0.5: 1, the titanium silicalite molecular sieve precursor and the titanium silicalite are both made of SiO₂And (6) counting.

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. The titanium-containing molecular sieve prepared by the preparation method of any one of claims 4 to 12.

14. A method for hydroxylating phenol, the method comprising contacting phenol and hydrogen peroxide with a titanium-containing molecular sieve under hydroxylation conditions, wherein the titanium-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 titanium-containing molecular sieve, a preparation method thereof and a phenol hydroxylation reaction method.

Background

Titanium silicalite is a new type of heteroatom molecular sieve developed in the beginning of the eighties of the twentieth century. The titanium-silicon molecular sieve synthesized at present has MFI structure TS-1, MEL structure TS-2, MWW structure MCM-22, larger pore structure TS-48 and the like.

TS-1 is the one developed and synthesized by EniChem corporation in Italy at the earliest, and is a new titanium-silicon molecular sieve with excellent catalytic selective oxidation performance formed by introducing transition metal element titanium into a molecular sieve framework with a ZSM-5 structure, and TS-1 not only has the catalytic oxidation effect of titanium, but also has the shape selective effect and excellent stability of the ZSM-5 molecular sieve. The titanium silicalite molecular sieve is used as a catalyst to catalyze various organic oxidation reactions, such as olefin epoxidation, alkane partial oxidation, alcohol oxidation, phenol hydroxylation, cyclic ketone ammoxidation and the like. As the TS-1 molecular sieve can adopt pollution-free low-concentration hydrogen peroxide as an oxidant in the oxidation reaction of organic matters, the problems of complex process and environmental pollution in the oxidation process are avoided, and the molecular sieve has the advantages of incomparable energy conservation, economy, environmental friendliness and the like of the traditional oxidation system and has good reaction selectivity.

The titanium silicalite molecular sieve is considered as a milestone in the field of molecular sieve catalysis as an organic selective oxidation catalyst, and can overcome the defects of complex reaction process, harsh conditions, serious environmental pollution and the like of the traditional catalytic oxidation system from the source, so that the titanium silicalite molecular sieve is highly valued by people at present with increasingly strict environmental protection requirements.

In 1983, a method for synthesizing a titanium silicalite molecular sieve by a hydrothermal crystallization method is reported by Taramasso in a patent US4410501 for the first time. The method is a classical method for synthesizing TS-1, and mainly comprises two steps of glue preparation and crystallization, wherein the synthesis process is as follows: putting Tetraethoxysilane (TEOS) into nitrogen to protect CO₂The preparation method comprises the following steps of slowly adding TPAOH (template agent), slowly adding tetraethyl titanate (TEOT) dropwise, stirring for lh to prepare a reaction mixture containing a silicon source, a titanium source and organic alkali, heating, removing alcohol, replenishing water, crystallizing for 10 days at 175 ℃ under stirring in an autogenous pressure kettle, separating, washing, drying and roasting to obtain the TS-1 molecular sieve. However, in the process, the influence factors of the process of inserting titanium into the framework are numerous, and the conditions of hydrolysis and nucleation are not easy to control, so that the TS-1 molecular sieve synthesized by the method has the defects of low catalytic activity, poor stability, difficulty in synthesis and reproduction and the like.

CN1260241A discloses a rearrangement technique of titanium-silicon molecular sieve, which synthesizes a novel titanium-silicon molecular sieve with a unique hollow structure, not only greatly enhances the reproducibility of synthesizing TS-1, but also increases the size of the molecular sieve pore, greatly improves the mass transfer diffusion rate of reactant molecules in the molecular sieve pore and increases the catalytic performance. The method disclosed in this patent combines a hydrolyzed solution of titanium with a synthesized TS-1 molecular sieve according to the following molecular sieve (g): ti (mol) 200-: 1, reacting the obtained mixture in a reaction kettle at 120-200 ℃ for 1-8 days, filtering, washing and drying. At present, the HTS molecular sieve is applied to the processes of phenol hydroxylation, cyclohexanone ammoximation and the like by catalytic oxidation, has already been industrialized, and has the advantages of mild reaction conditions, high atom utilization rate, simple process, clean and efficient water serving as a byproduct and the like.

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

In order to achieve the above object, the present invention provides a titanium-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 4-15nm, and the volume of the mesoporous grain boundary is 0.2-0.8 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 titanium-containing molecular sieve, comprising:

(1) mixing a titanium 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 titanium silicon oxide;

(5) mixing the titanium silicon oxide, the template agent, the seed crystal and/or the titanium silicon molecular sieve precursor, water and an inorganic ammonium source to obtain a second mixture, and then crystallizing;

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

Preferably, the molar ratio of the titanium source to the total silicon source used in step (1) is 0.005-0.05: 1, the titanium source is TiO₂The total silicon source is SiO₂Counting; the total silicon source is SiO₂Liquid silicon of meterSource and with 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, preferably 1: 2-8.

Preferably, the molar ratio of the template agent to the total silicon source is 0.08-0.6: 1.

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

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

According to the preparation method of the titanium-containing molecular sieve, the expensive liquid silicon source is partially replaced by the cheap and easily-obtained solid 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 titanium-containing molecular sieve material is obtained, and the prepared molecular sieve has higher oxidation activity. The preparation method of the titanium-containing molecular sieve provided by the invention can synthesize the small-grain stacked titanium-containing molecular sieve material under the conditions of lower template agent dosage and lower water-silicon ratio, can reduce the synthesis cost of the titanium-containing molecular sieve material, improves the solid content of the synthesized molecular sieve crystallized product, and improves the yield of the single-kettle molecular sieve. The titanium-containing molecular sieve prepared by the preparation method provided by the invention is used in the phenol hydroxylation reaction, and has higher reaction activity and selectivity.

Drawings

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

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

FIG. 3 is a TEM photograph of the Ti-MFI molecular sieve obtained from the rearrangement treatment of example 4;

FIG. 4 is an SEM photograph of the Ti-MFI molecular sieve prepared in comparative example 1;

FIG. 5 is a TEM photograph of the Ti-MFI molecular sieve prepared in comparative example 1;

FIG. 6 is an SEM photograph of a Ti-MFI molecular sieve obtained by the rearrangement treatment of comparative example 2;

FIG. 7 is a TEM photograph of a Ti-MFI molecular sieve obtained by the rearrangement treatment of comparative example 2;

fig. 8 is an XRD spectrum of the titanium-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 titanium-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 4-15nm, and the mesoporous volume of the grain boundary is 0.2-0.8 mL/g.

According to a preferred embodiment of the present invention, the molar ratio of titanium to silicon in the molecular sieve is 0.005 to 0.04: 1, preferably 0.02-0.035: 1.

according to the invention, the molecular sieve particles of the titanium-containing molecular sieve are obtained by stacking crystal grains with the particle size of 20-50nm through transmission electron microscope detection.

According to a preferred embodiment of the invention, the average grain size of the grains is 20-50nm, for example 25-45 nm.

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

The molecular sieve particles of the titanium-containing molecular sieve provided by the invention contain abundant crystal boundaries, and the crystal boundaries can strengthen mass transfer and diffusion of reactants and product molecules. The average grain boundary size of the molecular sieve particles of the titanium-containing molecular sieve provided by the invention is 4-15nm, and the mesoporous volume of the grain boundary is 0.2-0.8 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 0.19 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 titanium-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 titanium-containing molecular sieve, comprising:

(1) mixing a titanium 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 titanium silicon oxide;

(5) mixing the titanium silicon oxide, the template agent, the seed crystal and/or the titanium silicon molecular sieve precursor, water and an 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 titanium 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 titanium source is TiO₂The 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, for example 1: 2-8 or 1: 3-7. In the invention, the high proportion of solid silicon source is used, so that the production cost can be reduced, and in addition, the solid content of the crystallization product of the titanium-containing molecular sieve can be improved, thereby improving the output of single synthesis under the condition that the synthesis reaction kettle is not changed.

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

According to a preferred embodiment of the present invention, the inorganic titanium salt is at least one selected from the group consisting of titanium trichloride, titanium tetrachloride, titanium nitrate, titanyl sulfate and titanium sulfate, and is preferably titanium tetrachloride and/or titanyl sulfate.

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

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. Specifically, the solid silicon source may be a high-purity silica solid or powder, and preferably, the solid silicon source is white carbon and/or high-purity silica gel, preferably white carbon. 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 titanium 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 having 1 to 5 carbon atoms), such as ethanol and/or isopropanol.

The embodiment of mixing in step (1) is not particularly limited in the present invention, as long as the titanium 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 25-50 ℃; 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 titanium-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 titanium-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 titanium-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 0.2: 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 titanium-containing molecular sieve with small crystal grain stack can be synthesized under high solid content, so that the using amount of water can be reduced, the single-kettle yield is improved, namely more molecular sieves are synthesized under the same volume of a synthesis reactor, and the molar ratio of the water to the total silicon source in the step (5) is preferably 5-80: 1 or 5-50: 5-30: 1 or 6-20: 1 or 6-15: 1.

preferably, the molar ratio of the inorganic ammonium source in step (5) to the titanium source in step (1) is from 0.01 to 5: 1Preferably 0.01 to 4: 1, more preferably 0.01 to 0.5: 1, the inorganic ammonium source is NH₄ ⁺The titanium source is calculated as TiO₂And (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 titanium-containing molecular sieve is improved, the utilization rate of the titanium source (higher framework titanium-silicon ratio under the condition of the same titanium source usage) is improved, and the usage amount of the titanium 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.

According to a preferred embodiment of the present invention, the molar ratio of the titanium silicalite precursor in step (5) to the titanium silicalite oxide in step (1) is 0 to 1: 1, preferably 0.01 to 0.5: 1, the titanium silicalite molecular sieve precursor and the titanium silicalite are both made of SiO₂And (6) counting.

In the present invention, the precursor for synthesizing the titanium silicalite molecular sieve in step (5) is not particularly limited, and may be a titanium silicalite sol obtained after removing various alcohols conventionally used in the art, and specifically includes: mixing a titanium source, a silicon source, a template agent and water, aging, removing alcohol and the like. The skilled person can select a suitable titanium silicalite molecular sieve to synthesize a precursor according to the synthesized molecular sieve structure. The precursor for synthesizing the titanium silicalite molecular sieve can be synthesized according to the conventional technical means in the field. The titanium source, the silicon source and the template may be as described above, and are not described herein again. The amounts of the titanium source, silicon source, templating agent, and water can be selected according to conventional techniques in the art. For example, the molar ratio of the silicon source, the titanium source, the templating agent, and the water may be 1: (0.005-0.03): (0.05-0.3): (5-30).

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 100-130 deg.C (preferably 110-130 deg.C) for 0.5-1.5 days, and crystallizing at 160-180 deg.C for 1-3 days, wherein the crystallization pressure is autogenous pressure.

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 titanium 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 titanium-containing molecular sieve from the product obtained by crystallization in the step (5). The method for recovering the titanium-containing molecular sieve can be the 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 titanium-containing molecular sieve with small crystal grain stacks obtained by crystallization from the crystallization mother liquor, and the purpose of washing is to wash off the siliceous template adsorbed on the surface of the molecular sieve particles, for example, the molecular sieve particles can be mixed and washed at the temperature of room temperature to 50 ℃ and the weight ratio of the molecular sieve to water of 1 (1-20) such as 1 (1-15) and then filtered or rinsed by 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 titanium-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 120-200 ℃, more preferably 150-200 ℃; the second crystallization time is 0.5 to 10 days, more preferably 0.5 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-grain stacked titanium-containing molecular sieve has a hollow structure, and is called molecular sieve rearrangement 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 a titanium-containing molecular sieve from a 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. Through rearrangement treatment, the titanium-containing molecular sieve with more obvious mesoporous structure and stacked small crystal grains is obtained, and the rearranged titanium-containing molecular sieve has larger pore volume and specific surface area.

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

In a fourth aspect, the present invention provides a phenol hydroxylation reaction method, including contacting phenol and hydrogen peroxide with a titanium-containing molecular sieve under hydroxylation reaction conditions, where the titanium-containing molecular sieve is the titanium-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.

Preferably, 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.

In the present invention, preferably, 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 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 voltage 40kV, tube current 40mA, scanning speed 0.5 °/min, scanning range 2 θ is 4-40 °.

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 of the titanium-containing molecular sieve and the particle size of the crystal grains are obtained by transmission electron microscope detection (measured by a TEM scale).

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

The seed crystals are prepared according to the methods of the literature (Studies on the synthesis of titanium silicalite, TS-1Zeolite, 1992,12(8), 943-50).

The preparation method of the titanium silicalite molecular sieve precursor comprises the following steps: an amount of about 3/4 tetrapropylammonium hydroxide (TPAOH, 20%) solution was added to a Tetraethylorthosilicate (TEOS) solution to obtain a liquid mixture having a pH of about 13, and then the desired amount of n-butyl titanate [ Ti (OBu) ] was added dropwise to the resulting liquid mixture with vigorous stirring₄]Is stirred for 15 minutes to give a clear liquid, most preferablyThereafter, the remaining TPAOH was slowly added to the clarified liquid and stirred at 348 ℃ and 353K for about 3 hours to obtain a solution having a chemical composition of 0.03TiO₂：SiO₂：0.36TPA：35H₂A sol of O.

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

tetrabutyl titanate, analytically pure, chemical reagents of the national pharmaceutical group, ltd.

Titanium 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%.

In examples 1 to 13 of the present invention, SiO was used₂The total silicon source usage was fixed at 0.2 mol.

Example 1

(1) Titanium tetrachloride, tetraethyl silicate (TEOS), tert-butyl hydroperoxide and 3g of ethanol 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.

(2) And standing the obtained hydrolysate at room temperature for 12 hours for aging to obtain aged sol.

(3) Adding white carbon black powder into the aged sol under stirring, adding 8 wt% hydrochloric acid 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 TiO₂-SiO₂White oxide.

(5) Transferring the titanium silicon oxide, tetrapropylammonium hydroxide (TPAOH) aqueous solution with the concentration of 25.05 weight percent, hexadecyl trimethyl ammonium hydroxide (MSDS), seed crystals, titanium silicon molecular sieve precursors, ammonia water with the concentration of 20 weight percent and water into a stainless steel closed reaction kettle, crystallizing at the constant temperature of 165 ℃ for 2 days to obtain a crystallized sample, filtering, washing, drying at 120 ℃ for 24 hours, and roasting at 550 ℃ for 6 hours to obtain the titanium-containing molecular sieve S-1 with small crystal grain stacking structure, wherein the titanium-containing molecular sieve S-1 has an MFI structure.

The SEM and TEM photographs of the titanium-containing molecular sieve S-1 are shown in figures 1 and 2, and the XRD analysis spectrum is shown in figure 8.

As can be seen from fig. 1 and 2, the molecular sieve particles are formed by stacking crystal grains having a particle size 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 titanate, tetraethyl silicate (TEOS), polyacrylic acid powder 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.

(2) And standing the obtained hydrolysate at 37 ℃ for 24 hours for aging to obtain 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 TiO₂-SiO₂White oxide.

(5) Transferring the titanium silicon oxide, tetrapropylammonium hydroxide (TPAOH) aqueous solution with the concentration of 25.05 weight percent, hexadecyl trimethyl ammonium hydroxide (MSDS), seed crystals, titanium silicon molecular sieve precursors, ammonia water with the concentration of 20 weight percent and water into a stainless steel closed reaction kettle, crystallizing for 3 days at the constant temperature of 160 ℃ to obtain a crystallized sample, filtering, washing, drying for 24 hours at the temperature of 120 ℃, and roasting for 6 hours at the temperature of 550 ℃ to obtain the titanium-containing molecular sieve S-2 with small crystal grain stacking shape, wherein the titanium-containing molecular sieve S-2 has an MFI structure.

The SEM and TEM pictures of the titanium-containing molecular sieve S-2 are similar to those of the titanium-containing molecular sieve S-1, and an XRD analysis spectrogram 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.

Example 3

(1) Adding titanyl sulfate, silicon tetrachloride, polyacrylic acid powder (weight average molecular weight 5000) and 10g of isopropanol into a 100mL beaker in sequence, putting the beaker on a magnetic stirrer with heating and stirring functions, uniformly mixing, and stirring for 10 hours at room temperature.

(2) And standing the obtained hydrolysate at 20 ℃ for 9 hours for aging to obtain aged sol.

(3) Adding white carbon black powder into the aged sol under stirring, adding 30 wt% ammonia water 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 TiO₂-SiO₂White oxide.

(5) Transferring the titanium silicon oxide, tetrapropylammonium hydroxide (TPAOH) aqueous solution with the concentration of 25.05 weight percent, Cetyl Trimethyl Ammonium Bromide (CTAB), seed crystals, titanium silicon molecular sieve precursors, ammonia water with the concentration of 20 weight percent and water into a stainless steel closed reaction kettle, crystallizing at the constant temperature of 170 ℃ for 1.5 days to obtain a crystallized sample, filtering, washing, drying at 120 ℃ for 24 hours, and roasting at 550 ℃ for 6 hours to obtain the small-grain stacked titanium-containing molecular sieve S-3 with the MFI structure.

The SEM and TEM pictures of the titanium-containing molecular sieve S-3 are similar to those of the titanium-containing molecular sieve S-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 4

Taking the titanium-containing molecular sieve S-3 prepared in example 3 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 hollow small-grain stacked titanium-containing molecular sieve S-4, wherein the titanium-containing molecular sieve S-4 has an MFI structure.

The TEM photograph of the titanium-containing molecular sieve S-4 is shown in FIG. 3. 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 5 to 8

Titanium-containing molecular sieves were prepared according to the method of example 1, and the components and synthesis conditions of the titanium-containing molecular sieves are shown in table 1, to obtain small-grained stacked titanium-containing molecular sieves S-5 to S-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 9

The titanium-containing molecular sieve was prepared according to the method of example 1, except that in step (5), the titanium-containing molecular sieve was first crystallized at 120 ℃ for 1 day and then crystallized at 170 ℃ for 2 days, and the composition and synthesis conditions of the titanium-containing molecular sieve are shown in table 1, to obtain a titanium-containing molecular sieve S-9 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 10

A titanium-containing molecular sieve was prepared according to the method of example 1, except that the calcination temperature in step (4) was 850 ℃, the composition and synthesis conditions of the titanium-containing molecular sieve were as shown in table 1, and a small-grained stacked titanium-containing molecular sieve S-10 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.

Example 11

Preparing the titanium silicon micro mesoporous molecular sieve with the MEL structure. Referring to the method according to example 1, the composition and synthesis conditions of the titanium-containing molecular sieve are shown in table 1 by changing the mixture ratio and the template, and the titanium-containing molecular sieve S-11 with stacked small grains is 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.

Example 12

Preparing the titanium-silicon micro-mesoporous molecular sieve with the BEA structure. Referring to the method of example 1, the composition and synthesis conditions of the titanium-containing molecular sieve are shown in Table 1 by changing the mixture ratio and the template, and the titanium-containing molecular sieve S-12 with stacked small grains is 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.

Example 13

The procedure of example 1 was followed, except that tert-butylhydroperoxide was replaced with an equimolar amount of trimethylchlorosilane, to obtain titanium-containing molecular sieve S-13. 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 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 the action of vigorous stirring, a solution consisting of 1.1g of tetrabutyl titanate and 5g of isopropanol is slowly dropped into the solution, and the mixture is stirred at 75 ℃ for 3 hours to obtain a clear and transparent colloid. And then the colloid is moved into a stainless steel closed reaction kettle and crystallized for 3 days at the constant temperature of 170 ℃, thus obtaining the conventional titanium-containing molecular sieve D-1.

The SEM and TEM photographs of the titanium-containing molecular sieve D-1 are shown in FIGS. 4 and 5, 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.

Comparative example 2

Mixing 22.5g tetraethyl silicate with 9g tetrapropyl ammonium hydroxide, adding 64.5g deionized water, and uniformly mixing; then hydrolyzing for 1.0h at 60 ℃ to obtain a hydrolysis solution of tetraethyl silicate. Under the action of vigorous stirring, a solution consisting of 0.6g of tetrabutyl titanate and 7g of isopropanol is slowly dropped into the solution, and the mixture is stirred at 75 ℃ for 7 hours to obtain a clear and transparent colloid. Then the colloid is moved into a stainless steel closed reaction kettle and crystallized for 3 days at the constant temperature of 170 ℃, and the conventional titanium-containing molecular sieve is obtained.

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

The SEM and TEM photographs of the titanium-containing molecular sieve D-2 are shown in FIGS. 6 and 7, 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.

Comparative example 3

The procedure of example 1 was followed, except that no auxiliary (polyacrylic acid) was added, to obtain titanium-containing molecular sieve D-3. 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

The procedure of example 1 was followed, except that the inorganic ammonium source (ammonia water) was not added, and aging was not conducted, to obtain titanium-containing molecular sieve D-4. 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 titanium-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 titanium-containing molecular sieves prepared in the above examples 1 to 13 and comparative examples 1 to 5 were used as catalysts for phenol hydroxylation reaction to carry out phenol hydroxylation reaction.

1.25g of the titanium-containing molecular sieves prepared in examples 1 to 13 and comparative examples 1 to 5 were added to a three-necked flask reaction vessel containing 25g of phenol and 20mL of acetone, respectively, and after the temperature stabilized to 78 ℃, hydrogen peroxide of 30 wt% concentration, phenol: hydrogen peroxide (with H)₂O₂In terms of) is 1: 0.3, reacting at 78 deg.C and 0.1MPa for 2 hr, sampling, and separating with gas chromatographThe concentrations of the reacted substances were quantitatively analyzed, and the phenol conversion rate, catechol selectivity, and hydroquinone selectivity were calculated, and the specific results are shown in table 2.

TABLE 1

TABLE 1

Note: TPABr is tetrapropylammonium bromide, TEAOH is tetraethylammonium hydroxide, CTMAB is cetyltrimethylammonium bromide, DTAB is dodecyltrimethylammonium hydroxide, MSDS is cetyltrimethylammonium hydroxide, TBAOH is tetrabutylammonium hydroxide.

TABLE 2

From the data in table 2, it can be seen that the titanium-containing molecular sieve of the present invention has a smaller grain size, a larger mesoporous volume and a larger benzene adsorption capacity than the existing titanium-containing molecular sieve. The titanium-containing molecular sieve provided by the invention can be 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.