阅读说明：本技术 含锡分子筛的制备方法以及由该方法生产的含锡分子筛和环己酮肟化反应方法 (Preparation method of tin-containing molecular sieve and oximation reaction method of tin-containing molecular sieve and cyclohexanone produced by method ) 是由 夏长久 林民 彭欣欣 朱斌 舒兴田 于 2019-10-30 设计创作，主要内容包括：本发明涉及催化剂领域,具体涉及一种含锡分子筛的制备方法以及由该方法生产的含锡分子筛和一种环己酮肟化反应方法。该方法包括：(1)将锡源、硅源、助剂和溶剂混合,得到第一混合物；(2)在含氧气氛中,将所述第一混合物进行燃烧,得到锡硅氧化物；(3)将所述锡硅氧化物、模板剂、晶种、液体锡硅分子筛合成前驱体、水和无机铵源混合,得到第二混合物,然后进行晶化；其中,所述助剂包括空间填充剂和/或稳定剂。本发明提供的制备方法制得的含锡分子筛用于环己酮肟化反应中,具有较高的反应活性和选择性。(The invention relates to the field of catalysts, and particularly relates to a preparation method of a tin-containing molecular sieve, the tin-containing molecular sieve produced by the method and a cyclohexanone oximation reaction method. The method comprises the following steps: (1) mixing a tin source, a silicon source, an auxiliary agent and a solvent to obtain a first mixture; (2) combusting the first mixture in an oxygen-containing atmosphere to obtain tin silicon oxide; (3) mixing the tin silicon oxide, a template agent, a seed crystal, a liquid tin silicon molecular sieve synthesis 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. The tin-containing molecular sieve prepared by the preparation method provided by the invention is used in cyclohexanone oximation reaction, and has higher reaction activity and selectivity.)

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

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

(2) combusting the first mixture in an oxygen-containing atmosphere to obtain tin silicon oxide;

(3) mixing the tin silicon oxide, a template agent, a seed crystal, a liquid tin silicon molecular sieve synthesis 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.

2. The production method according to claim 1,

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 silicon source in the step (1) is 0.01-0.1: 1, preferably 0.02 to 0.07: 1, wherein the silicon source is SiO₂And (6) counting.

3. The production method according to claim 1, 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 SiO₂The total silicon source is SiO₂Tin silicon oxide and in SiO₂The sum of the precursors synthesized by the liquid tin-silicon molecular sieve is counted;

preferably, SiO is used in step (2)₂Calculated tin silicon oxide and SiO in step (3)₂The molar ratio of the liquid tin-silicon molecular sieve synthetic precursor is 1: 0.01 to 0.2, preferably 1: 0.01-0.15;

preferably, the silicon source in step (1) is a liquid silicon source, and further preferably at least one selected from the group consisting of water-soluble inorganic silicon salts and silicates.

4. The production method according to claim 1, wherein the conditions of the combustion in step (2) include: the burning temperature is 400-850 ℃, preferably 450-750 ℃, and the burning time is 1-20 hours, preferably 2-10 hours.

5. The production method according to any one of claims 1 to 4, wherein the templating agent in step (3) 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; of said fatty aminesHas the general formula 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.

6. The method of claim 5, wherein 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 to the total silicon source in step (3) is 0.08-0.6: 1, preferably 0.1 to 0.3: 1, more preferably 0.1 to 0.25: 1, more preferably 0.1 to 0.2: 1.

7. the production method according to any one of claims 1 to 6, wherein in the second mixture in step (3), 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;

preferably, the molar ratio of the water to the total silicon source in step (3) is 5-100: 1, preferably 5 to 50: 1, more preferably 6 to 30: 1;

preferably, the molar ratio of the inorganic ammonium source in step (3) to the tin source in step (1) is 0.01 to 4: 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.

8. The production method according to any one of claims 1 to 7, wherein the crystallization conditions in step (3) 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.

9. The production method according to any one of claims 1 to 8, wherein the method further comprises a step (4), and the step (4) comprises: mixing the solid product obtained in the step (3), 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 (3) and/or the second crystallized product obtained in step (4).

10. A tin-containing molecular sieve prepared by the method of any one of claims 1 to 9.

11. The tin-containing molecular sieve of claim 10, wherein the tin-containing molecular sieve particles are formed by stacking crystal grains with a particle size of 20-50nm, the tin-containing molecular sieve particles have a particle size of 100-500nm, the tin-containing molecular sieve particles have an average grain boundary size of 1-8nm, and the grain boundary mesoporous volume is 0.1-0.5 mL/g.

12. The tin-containing molecular sieve of claim 11, wherein the tin-containing molecular sieve particles have an average grain boundary size of 2-5nm and a grain boundary mesopore volume of 0.2-0.35 mL/g.

13. The tin-containing molecular sieve of claim 10, wherein the tin-containing molecular sieve is at 25 ℃, P/P₀(ii) an adsorbed benzene amount of at least 50 mg/g as measured at an adsorption time of 1 hour, 0.1;

preferably, the Lewis acid content of the tin-containing molecular sieve is 200-300 mu mol/g;

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

14. A cyclohexanone oximation reaction process comprising contacting cyclohexanone, ammonia, and hydrogen peroxide with a tin-containing molecular sieve under oximation reaction conditions, wherein the tin-containing molecular sieve is the tin-containing molecular sieve of any one of claims 10-13.

Technical Field

The invention relates to the field of catalysts, and particularly relates to a preparation method of a tin-containing molecular sieve, the tin-containing molecular sieve produced by the method and a cyclohexanone oximation 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 tin atoms isomorphously replace framework silicon to synthesize TS-1 molecular sieves, the synthesis of tin-containing microporous or mesoporous molecular sieves has rapidly attracted great attention, and a great deal of research work has been invested, and good progress has been made in synthesis and application, so that industrial production has been realized, and the synthesis 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 tin. 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 California university 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 active 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 synthesize the Sn-beta molecular sieve by adopting white carbon black to replace silicone grease, ammonium fluoride to replace hydrofluoric acid and adopting a dry glue conversion method. However, the large size (> 2 μm) of the synthesized molecular sieves greatly limits the diffusion of the reactant molecular sieves.

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 thatHigh crystallization temperature, kettle bottom water content and TPAOH/SiO₂And 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 a tin-silicon molecular sieve in the prior art mainly takes micropores as main components, has small mesoporous volume and is difficult to synthesize, and provides a preparation method of a tin-containing molecular sieve, the tin-containing molecular sieve produced by the method and a cyclohexanone oximation 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, a first aspect of the present invention provides a method for preparing a tin-containing molecular sieve, the method comprising:

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

(2) combusting the first mixture in an oxygen-containing atmosphere to obtain tin silicon oxide;

(3) mixing the tin silicon oxide, a template agent, a seed crystal, a liquid tin silicon molecular sieve synthesis 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 auxiliary agent to the silicon source in the step (1) is 0.01-0.1: 1, preferably 0.02 to 0.07: 1, wherein the 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, the tin source is SnO₂The total silicon source is countedWith SiO₂The total silicon source is SiO₂Tin silicon oxide and in SiO₂And (4) calculating the sum of the synthesized precursors of the liquid tin-silicon molecular sieve.

Preferably, SiO is used in step (2)₂Calculated tin silicon oxide and SiO in step (3)₂The molar ratio of the liquid tin-silicon molecular sieve synthetic precursor is 1: 0.01-0.2.

Preferably, the molar ratio of the template to the total silicon source in step (3) is 0.08-0.6: 1.

preferably, in the second mixture in the step (3), the content of the seed crystal is 0.1 to 5% by weight.

Preferably, the molar ratio of the water to the total silicon source in step (3) is 5-100: 1.

preferably, the molar ratio of the inorganic ammonium source in step (3) to the tin source in step (1) is 0.01 to 4: 1.

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

Preferably, the tin-containing molecular sieve particles are formed by stacking crystal grains with the particle size of 20-50nm, the particle size of the tin-containing molecular sieve particles is 100-500nm, the average grain boundary size of the tin-containing molecular sieve particles is 1-8nm, and the mesoporous volume of the grain boundary is 0.1-0.5 mL/g.

In a third aspect, the invention provides a cyclohexanone oximation reaction method, which comprises the step of contacting cyclohexanone, ammonia and hydrogen peroxide with the tin-containing molecular sieve prepared by the preparation method under oximation reaction conditions.

The preparation method of the tin-containing molecular sieve provided by the invention can reduce waste discharge in the production process of the molecular sieve, save raw material cost and obtain the high-performance small-crystal-grain stacked tin-containing molecular sieve, and the prepared tin-containing molecular sieve has higher catalytic conversion activity. The preparation method of the small-grain stacked tin-containing molecular sieve can synthesize the small-grain stacked tin-containing molecular sieve under the conditions of lower template agent dosage and lower water-silicon ratio, can reduce the synthesis cost of the small-grain stacked 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 cyclohexanone oximation 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.

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

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

(2) combusting the first mixture in an oxygen-containing atmosphere to obtain tin silicon oxide;

(3) mixing the tin silicon oxide, a template agent, a seed crystal, a liquid tin silicon molecular sieve synthesis 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.

In the present invention, preferably, the molar ratio of the auxiliary agent to the silicon source in step (1) is 0.01 to 0.1: 1, preferably 0.02 to 0.07: 1, wherein the 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 SiO₂Tin silicon oxide and in SiO₂And (4) calculating the sum of the synthesized precursors of the liquid tin-silicon molecular sieve.

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 silicon source in the step (1) is not particularly limited, and a liquid silicon source is preferable. Specifically, the silicon source is selected from at least one of water-soluble inorganic silicon salts and silicates.

According to a preferred embodiment of the invention, the inorganic silicon salt is selected from silicon tetrachloride and/or sodium silicate.

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

In the present invention, the kind and amount of the solvent used in the step (1) are not particularly limited. The tin source, the 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 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 present invention, the conditions for the combustion in the step (2) can be selected within a wide range as long as the requirement that the first mixture can be combusted is satisfied. Preferably, the conditions of the combustion in step (2) include: the burning temperature is 400-850 ℃, preferably 450-750 ℃, and the roasting time is 1-20 hours, preferably 2-10 hours.

According to a preferred embodiment of the present invention, the first mixture is combusted at 400-850 ℃ for 1-20 hours in an oxygen-containing atmosphere to obtain tin-silicon oxide.

The oxygen-containing atmosphere is not particularly limited in the present invention, and may be pure oxygen or a mixed gas of oxygen and other gases as long as it can provide oxygen required for combustion.

In the invention, SnO in tin-silicon oxide is taken as a standard on a dry basis₂And SiO₂The 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. The specific surface area of the tin silicon oxide is 50-550m²(iii) the total mass content of Fe, Al and Na impurities is less than 10 ppm.

In the present invention, preferably, in the tin-silicon oxide, the tin-silicon ratio is between 0.01 and 0.04, and only Si — O — Sn bonds are present around tin atoms, and Sn — O — Sn bonds are hardly present.

According to one embodiment of the present invention, the first mixture prepared in step (1) is injected into an alcohol burner, and the above solution is ignited in an oxygen-containing atmosphere, and the tin source and the silicon source react at a temperature of 400-.

According to the invention, step (2) is preferably carried out with SiO₂Calculated tin silicon oxide and SiO in step (3)₂The molar ratio of the liquid tin-silicon molecular sieve synthetic precursor is 1: 0.01 to 0.2, more preferably 1: 0.01-0.15, such as 1: 0.02-0.08 or 1: 0.03-0.07.

In the present invention, the template in the step (3) 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, 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 (3) 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 (3) 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 (3) to the tin source in step (1) is 0.01 to 4: 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. 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 is improved (the tin-silicon ratio of the framework is higher under the condition of the same tin source usage amount), the usage amount of the tin source is reduced, and the molecular sieve prepared by the method has higher acid center number and acid strength under the condition of the same tin-silicon ratio.

In the present invention, the inorganic ammonium source in the step (3) 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.

According to a preferred embodiment of the present invention, in the second mixture in step (3), the content of the seed crystals 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 (3) 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, there is no particular limitation on the precursor for synthesizing the liquid tin-silicon molecular sieve in step (3), and the precursor may be a product of step 1 of synthesizing a precursor by using various liquid tin-silicon molecular sieves conventionally used in the art, and specifically includes: mixing a tin source, a silicon source, a template agent and water, aging, removing alcohol and the like. The person skilled in the art can select a suitable liquid tin-silicon molecular sieve to synthesize a precursor according to the synthesized molecular sieve structure. The precursor for synthesizing the liquid tin-silicon molecular sieve can be synthesized according to the conventional technical means in the field. The types of the tin source, the silicon source and the template agent can be as described above, and are not described herein again. The amounts of the tin source, silicon source, templating agent, and water used can be selected according to conventional techniques in the art. For example, the molar ratio of the silicon source, the tin source, the templating agent, and the water may be 1: (0.005-0.03): (0.05-0.3): (5-30).

According to the present invention, a silicon source may also optionally be added in step (3). The selection of the silicon source is as described above, and is not described herein again. According to a preferred embodiment of the present invention, the step (3) comprises: and mixing the tin-silicon oxide, the template agent, the seed crystal, the precursor synthesized by the liquid tin-silicon molecular sieve, water, the inorganic ammonium source and the silicon source to obtain a second mixture, and then crystallizing. Wherein SiO is used in the step (3)₂Counting the silicon source and taking SiO in the step (1)₂The molar ratio of the silicon source may be 0.1 to 10: 1.

in the present invention, the crystallization is not particularly limited. Preferably, the crystallization conditions in step (3) 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 invention, the method can also comprise recovering the tin-containing molecular sieve from the product obtained by crystallization in the step (3). 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 a temperature of room temperature to 50 ℃ and a 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 (4), the step (4) comprising: and (4) mixing the solid product obtained in the step (3), 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 (3), 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 (3) (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 an organic amine and/or an organic quaternary ammonium base, the organic amine and the organic quaternary ammonium base being as defined aboveThe present invention is not described herein in detail.

Specifically, the method can also comprise recovering the tin-containing molecular sieve from the product obtained by crystallization in the step (4). Generally comprises filtering, washing, drying and then roasting the crystallized product, and the recovery method described in step (3) can be referred to, and the present invention is not described herein.

In the present invention, the rearrangement of the molecular sieve step (4) may be performed once or 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 second aspect, the invention provides a tin-containing molecular sieve prepared by the above preparation method.

According to the invention, preferably, 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 1-8nm, and the mesoporous volume of the grain boundary is 0.1-0.5 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 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 crystal boundaries, and the crystal boundaries not only strengthen mass transfer diffusion of reactant and product molecules, but also improve the Lewis acid content of framework tin species. The average grain boundary size of the molecular sieve particles of the tin-containing molecular sieve provided by the invention is 1-8nm, and the mesoporous volume of the grain boundary is 0.1-0.5 mL/g.

According to a preferred embodiment of the present invention, the molecular sieve particles have an average grain boundary size of 2 to 5nm and a grain boundary mesopore volume of 0.2 to 0.35 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.

According to a preferred embodiment of the present invention, the molecular sieve has a specific surface area of 500-550m²/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 2 and 5 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 present invention, the tin-containing molecular sieve has a Lewis acid content of 200-300. mu. mol/g. The acid content of the molecular sieve was determined by pyridine adsorption infrared spectroscopy.

According to a preferred embodiment of the invention, the molecular sieve is at 25 ℃ P/P₀The amount of benzene adsorbed is at least 50 mg/g, preferably 50 to 60 mg/g, as measured under the condition of an adsorption time of 1 hour ═ 0.1. A hysteresis loop exists between the adsorption isotherm and the desorption isotherm of the low-temperature nitrogen adsorption of the molecular sieve. Under the same tin-silicon ratio, the acid content and the acid strength of the tin-containing molecular sieve provided by the invention are higher than those of the tin-containing molecular sieve prepared by the conventional method.

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 third aspect, the invention provides a cyclohexanone oximation reaction method, which comprises contacting cyclohexanone, ammonia and hydrogen peroxide with the tin-containing molecular sieve provided by the preparation method under oximation reaction conditions.

The cyclohexanone oximation reaction method according to the present invention is not particularly limited in the oximation reaction conditions,can be carried out under conventional conditions. Specifically, the oximation reaction conditions comprise: the reaction temperature is 40-120 ℃, preferably 50-100 ℃, the reaction pressure is 0-5MPa, preferably 0.1-3MPa, and the volume space velocity is 5-15h^-1Preferably 5-10h^-1。

In the present invention, preferably, the molar ratio of cyclohexanone, ammonia and hydrogen peroxide is 1: 0.2-5: 0.2 to 5, preferably 1: 1-3: 1-3.

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, t-butanol 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, more preferably 50 to 2000 parts by weight, relative to 100 parts by weight of cyclohexanone.

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 BET specific surface area and pore volume were 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 acid content of the tin-containing molecular sieve was determined by pyridine adsorption infrared spectroscopy.

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,29Si liquid and solid MAS-NMR,119Sn static and MAS NMR students [ J ]. Microporous Materials,1997,12(4-6): 331-340.).

The precursor synthesized by the liquid tin-silicon molecular sieve is obtained by a conventional method, and specifically comprises the following steps: the pentahydrate stannic chloride (SnCl)₄·5H₂O) is dissolved in water, the water solution is added with tetraethyl orthosilicate (TEOS) and stirred, tetrapropylammonium hydroxide (TPAOH, 20 percent water solution) and water are added under stirring, and the stirring is continued for 30 minutes to obtain the SnO with the chemical composition of 0.03SnO₂：SiO₂：0.45TPA：35H₂A clear liquid of O. Wherein the amount of TEOS is 15.31g, the amount of TPAOH is 33.67g, and SnCl₄·5H₂The amount of O was 0.38g and the amount of water was 39.64 g.

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.

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

The gas chromatograph is purchased from Agilent company and is model 6890, and the analytical chromatographic column is an FFAP column.

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, BET specific surface area, benzene adsorption amount and Lewis acid 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, BET specific surface area, benzene adsorption amount and Lewis acid amount of the molecular sieve are shown in Table 2.

Examples 1 to 11 of the present invention are made of SiO₂The total silicon source usage was fixed at 0.2 mol.

Example 1

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

(2) The first mixture was burned at 500 ℃ for 5 hours in an air atmosphere to obtain tin silicon oxide.

(3) Mixing the tin silicon oxide, tetrapropylammonium hydroxide (TPAOH) aqueous solution with the concentration of 25.05 weight percent, hexadecyl trimethyl ammonium hydroxide (MSDS), seed crystals, liquid tin silicon molecular sieve synthetic precursor, ammonia water with the concentration of 20 weight percent and water to obtain a second mixture, then transferring the second mixture into a stainless steel closed reaction kettle, crystallizing the second mixture at the constant temperature of 165 ℃ for 2 days to obtain a crystallized sample, filtering and washing the crystallized sample, drying the crystallized sample at the temperature of 120 ℃ for 24 hours, and roasting the crystallized sample at the temperature of 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, BET specific surface area, benzene adsorption amount and Lewis acid amount of the molecular sieve are shown in Table 2.

Example 2

(1) Tin tetrachloride, tetraethyl silicate (TEOS), polyacrylic acid powder and 10g of ethanol are sequentially added into a 500mL beaker, placed on a magnetic stirrer with heating and stirring functions, uniformly mixed and stirred at 40 ℃ for 10 hours to obtain a first mixture.

(2) The first mixture was burned at 450 ℃ for 4 hours in an air atmosphere to obtain tin silicon oxide.

(3) Mixing the tin silicon oxide, tetrapropylammonium hydroxide (TPAOH) aqueous solution with the concentration of 25.05 weight percent, hexadecyl trimethyl ammonium hydroxide (MSDS), seed crystals, a precursor synthesized by a liquid tin silicon molecular sieve, tetraethyl silicate, ammonia water with the concentration of 20 weight percent and water to obtain a second mixture, then transferring the second mixture into a stainless steel closed reaction kettle, crystallizing the second mixture at the constant temperature of 160 ℃ for 3 days 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, BET specific surface area, benzene adsorption amount and Lewis acid 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 wt% 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, BET specific surface area, benzene adsorption amount and Lewis acid 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, BET specific surface area, benzene adsorption amount and Lewis acid amount of the molecular sieve are shown in Table 2.

Example 8

A tin-containing molecular sieve was prepared in accordance with the procedure of example 1, except that in step (3), the tin-containing molecular sieve was crystallized first at 120 ℃ for 1 day and then at 170 ℃ for 2 days, and the composition and synthesis conditions of the tin-containing molecular sieve are shown in Table 1, to obtain 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, BET specific surface area, benzene adsorption amount and Lewis acid 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, BET specific surface area, benzene adsorption amount and Lewis acid 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, BET specific surface area, benzene adsorption amount and Lewis acid amount of the molecular sieve are shown in Table 2.

Example 11

The procedure of example 1 was followed, except that polyacrylic acid was replaced with an equimolar amount of trimethylchlorosilane, 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, BET specific surface area, benzene adsorption amount and Lewis acid amount of the molecular sieve are shown in Table 2.

Comparative example 3

Following the procedure of example 1, except that no inorganic ammonium source (ammonia water) was added in step (3), 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, BET specific surface area, benzene adsorption amount and Lewis acid 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 (aqueous ammonia) was not added in step (3), and the first mixture was not combusted in step (2), to obtain tin-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, BET specific surface area, benzene adsorption amount and Lewis acid amount of the molecular sieve are shown in Table 2.

Test example

The tin-containing molecular sieves prepared in examples 1 to 11 and comparative examples 1 to 4 above were used as catalysts for cyclohexanone oximation reaction to carry out oximation reaction.

According to the tin-containing molecular sieve: tert-butanol (solvent): 25 wt% ammonia 1: 7.5: 7.5 in mass ratio (wherein the weight of the aqueous ammonia is NH)₃Metering) the slurry bed was stirred uniformly and mixed, the temperature was raised to 75 ℃ and the amount of the tin-containing molecular sieve was 2.6 g. Then 30 wt% hydrogen peroxide was added at a rate of 6mL/h, a mixture of cyclohexanone and t-butanol (the volume ratio of cyclohexanone to t-butanol was 1: 2.5) was added at a rate of 8.6mL/h, and simultaneously 6mL/h was addedAdding 25 weight percent of ammonia water solution, and the volume space velocity is 7.92h^-1. The three materials are added simultaneously, and are discharged continuously at corresponding speed, 3 hours after the reaction is stable, a gas chromatograph is used for carrying out quantitative analysis on the concentration of each substance after the reaction, the cyclohexanone conversion rate and the cyclohexanone oxime selectivity are calculated, and specific results are shown in table 2.

The conversion rate of cyclohexanone and the selectivity of cyclohexanone oxime are respectively calculated according to the following formulas:

TABLE 1

Note: the tetraethyl silicate used in Table 1 is tetraethyl silicate added in step (3).

TABLE 1

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

TABLE 2

As can be seen from the data in Table 2, the tin-containing molecular sieve of the present invention has smaller grain size, larger mesopore volume, BET specific surface area, benzene adsorption amount and Lewis acid amount compared with the existing tin-containing molecular sieve. The tin-containing molecular sieve provided by the invention can be used as a catalyst for cyclohexanone oximation reaction, and more excellent catalytic performance can be obtained.

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.