CN112744835A - Tin-silicon molecular sieve, preparation method thereof and cyclohexanone oximation reaction method - Google Patents
Tin-silicon molecular sieve, preparation method thereof and cyclohexanone oximation reaction method Download PDFInfo
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Abstract
The invention relates to the field of molecular sieve preparation, in particular to a tin-silicon molecular sieve, a preparation method thereof and a cyclohexanone oximation 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 500-1000nm, the average grain boundary size of the molecular sieve particles is 1-5nm, the mesoporous volume of the grain boundary is 0.1-0.5mL/g, and the Lewis acid weight of the molecular sieve is 200-300 mu mol/g. The preparation method provided by the invention can synthesize the small-grain stacked tin-silicon molecular sieve under the conditions of lower template agent dosage and lower water-silicon ratio, reduce the synthesis cost, improve the solid content of the synthesized molecular sieve crystallization product and improve the yield of the single-kettle molecular sieve. The tin-silicon molecular sieve provided by the invention is used in cyclohexanone oximation reaction, and has higher reaction activity and selectivity.
Description
Technical Field
The invention relates to the field of molecular sieve preparation, in particular to a tin-silicon molecular sieve, a preparation method thereof and a cyclohexanone oximation reaction method.
Background
Since Taramasso et al in 1983 disclosed that titanium atoms isomorphously substituted framework silicon synthesized TS-1 molecular sieves, the synthesis of titanium-containing microporous or mesoporous molecular sieves has rapidly attracted much attention and invested a great deal of research work, and both the synthesis and application have made good progress, and the industrial production has been realized and the method is successively applied to commercial processes such as phenol hydroxylation, cyclohexanone ammoximation, propylene epoxidation and the like.
Following the TS-1 molecular sieve, the tin-silicon molecular sieve materials (mainly including Sn-MFI and Sn-BEA molecular sieves) are mainly due to the physicochemical properties of tin atoms similar to those of transition metal titanium. Among the findings of milestone significance are:
(1) in 1994, Ramaswamy synthesizes the Sn-MFI molecular sieve by a conventional hydrothermal method for the first time.
(2) 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.
(3) The M.Davis team of the university of California in 2010 discovers that the Sn-beta molecular sieve has high activity in preparing fructose through catalyzing glucose isomerization, and the materials are considered to successfully simulate the metal activity center of glucose isomerase and break through the influence of temperature, pH value and the like on enzyme catalytic activity. In recent years, people have invested great efforts in the research of tin-silicon molecular sieve materials and have made very good progress.
At present, the synthesis and characterization of tin-silicon molecular sieves still have a large bottleneck, and no commercial production route is developed, because:
(1) radius of tin ion
Greater than silicon ion
Leading tin ions to be difficult to enter the framework of the molecular sieve;
(2) in a synthesis system with a higher tin-silicon molar ratio, tin ions delay the nucleation and growth of the molecular sieve to a great extent, so that the tin-silicon molecular sieve has poor crystallinity;
(3) for Sn-beta molecular sieves, the BEA structural framework is difficult to form, and a fluorine-containing reagent is usually required to be introduced to cause environmental pollution;
(4) the tin source is generally sensitive to a strong alkaline environment and is easy to hydrolyze and self-polymerize;
(5) anions contained in the tin source (e.g. Cl)-Ions) have an effect on the nucleation and growth of molecular sieve crystals.
Kangshenghua and the like adopt white carbon black to replace silicone grease and ammonium fluoride to replace hydrofluoric acid, and adopt a dry glue conversion method to synthesize the Sn-beta molecular sieve, but the synthesized molecular sieve has larger size (larger than 2 mu m) and greatly limits the diffusion of a reactant molecular sieve.
The synthesis of Sn-MFI molecular sieves by the dry gel method was first reported by Bokade et al. The authors examined in detail the temperature, time, amount of kettle bottom water, different TPAOH/SiO2And SiO2/SnO2The influence of parameters such as molar ratio on the crystallinity and physicochemical properties of the final sample. The results show that the crystallization temperature, the kettle bottom water amount and the TPAOH/SiO are improved2And SiO2/SnO2The molar ratio can shorten the crystallization time as a whole. In the phenol hydroxylation reaction, the Sn-MFI molecular sieve synthesized by the dry glue method and the Sn-MFI molecular sieve synthesized by the traditional hydrothermal method show equivalent activity.
The tin-silicon molecular sieve synthesized by the existing method mainly takes micropores as main components, and the mesoporous volume is small, so that the mass transfer and diffusion in crystals are not facilitated; and the synthesis difficulty of the molecular sieve is higher.
Disclosure of Invention
The invention aims to solve the problems that the synthesized tin-silicon molecular sieve mainly takes micropores as main components, has smaller mesoporous volume and higher synthesis difficulty in the prior art, and provides a tin-silicon molecular sieve, a preparation method thereof and a cyclohexanone oximation reaction method. The preparation method of the tin-silicon molecular sieve provided by the invention can save the cost of raw materials and obtain the high-performance small-grain stacked tin-silicon molecular sieve, and the prepared tin-silicon molecular sieve has higher oxidation activity and selectivity.
In order to achieve the above object, the first aspect of the present invention provides a tin-silicon 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 500-1000nm, the average grain boundary size of the molecular sieve particles is 1-5nm, the grain boundary mesoporous volume is 0.1-0.5mL/g, and the Lewis acid amount of the molecular sieve is 200-300 μmol/g.
Preferably, the molecular sieve is at 25 ℃, P/P0The benzene adsorption amount measured under the condition of adsorption time of 1 hour is at least 30 mg/g, which is 0.1.
In a second aspect, the present invention provides a method for preparing a tin-silicon molecular sieve, the method comprising:
(1) mixing a first liquid tin source, a first 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) heating the aged gel and the solid silicon source to obtain solid gel;
(4) roasting the solid gel to obtain tin silicon oxide;
(5) and mixing the tin-silicon oxide, the template agent, the second liquid tin source, the second liquid silicon source, water and the inorganic ammonium source to obtain a second mixture, and then crystallizing.
Preference is given toIn step (1), SnO is used2Metering a first liquid tin source and SnO in step (5)2The molar ratio of the second liquid tin source is 1: 0.1 to 10, preferably 1: 0.5-2.
Preferably, SiO is used in step (1)2The first liquid silicon source and SiO in step (5)2The molar ratio of the second liquid silicon source is 1: 0.1 to 10, preferably 1: 0.5-2.
Preferably, the molar ratio of the total tin source to the total silicon source is 0.005-0.05: 1, wherein the total tin source is SnO2The total silicon source is SiO2The total tin source is SnO2A first liquid tin source and SnO2The sum of the second liquid tin source and the total silicon source is SiO2First liquid silicon source in terms of SiO2Second liquid silicon source and SiO2The sum of the calculated solid silicon sources.
Preferably in SiO2The total liquid silicon source and SiO in 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, preferably 0.1 to 0.3: 1, more preferably 0.1 to 0.2: 1. the preparation method provided by the invention can synthesize the small-grain stacked tin-silicon molecular sieve material under the condition of lower template agent dosage, and can reduce the synthesis cost of the tin-silicon molecular sieve material.
Preferably, the molar ratio of the water to the total silicon source in step (5) is 5-100: 1, preferably 5 to 50: 1, more preferably 5 to 30: 1. the preparation method provided by the invention can synthesize the small-grain stacked tin-silicon molecular sieve material under the condition of a lower water-silicon ratio, can improve the solid content of a synthesized molecular sieve crystallization product, and can improve the yield of the single-kettle molecular sieve.
Preferably, the molar ratio of the inorganic ammonium source in step (5) to the first liquid tin source in step (1) is from 0.01 to 5: 1.
in a third aspect, the invention provides a tin-silicon molecular sieve prepared by the preparation method.
The fourth aspect of the invention provides a cyclohexanone oximation reaction method, which comprises the step of contacting cyclohexanone, ammonia and hydrogen peroxide with a tin-silicon molecular sieve under an oximation reaction condition, wherein the tin-silicon molecular sieve is the tin-silicon molecular sieve provided by the invention.
According to the preparation method of the tin-silicon molecular sieve, the cheap and easily-obtained solid silicon source is used for partially replacing the expensive liquid silicon source, so that the waste discharge in the production process of the molecular sieve can be reduced, the raw material cost is saved, and meanwhile, the high-performance small-crystal-grain stacked tin-silicon molecular sieve material is obtained, and the prepared molecular sieve has higher oxidation activity. The preparation method of the tin-silicon molecular sieve provided by the invention can synthesize the small-grain stacked tin-silicon molecular sieve material under the conditions of lower template agent dosage and lower water-silicon ratio, can reduce the synthesis cost of the tin-silicon 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-silicon 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 the Sn-MFI molecular sieve prepared in example 1;
FIG. 2 is a TEM photograph of the Sn-MFI molecular sieve prepared in example 1;
FIG. 3 is a TEM photograph of the Sn-MFI molecular sieve obtained from the rearrangement treatment of example 3;
FIG. 4 is an SEM photograph of the Sn-MFI molecular sieve prepared in comparative example 1;
FIG. 5 is a TEM photograph of the Sn-MFI molecular sieve prepared in comparative example 1;
FIG. 6 is an SEM photograph of the Sn-MFI molecular sieve obtained by the rearrangement treatment of comparative example 2;
FIG. 7 is a TEM photograph of the Sn-MFI molecular sieve obtained by the rearrangement treatment of comparative example 2;
fig. 8 is an XRD spectrum of the tin-silicon 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 first aspect of the invention provides a tin-silicon 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 500-1000nm, the average grain boundary size of the molecular sieve particles is 1-5nm, the grain boundary mesoporous volume is 0.1-0.5mL/g, and the Lewis acid weight of the molecular sieve is 200-300 mu mol/g.
According to the invention, the molecular sieve particles of the tin-silicon molecular sieve are obtained by stacking crystal grains with the particle size of 20-50nm through transmission electron microscope detection.
According to the invention, the particle size of the molecular sieve particles and the particle size of the crystal grains of the tin-silicon molecular sieve are obtained by transmission electron microscope detection (measured by a TEM scale).
According to a preferred embodiment of the present invention, the molar ratio of tin to silicon in the molecular sieve is 0.005 to 0.04: 1, preferably 0.01-0.035: 1.
the molecular sieve particles of the tin-silicon molecular sieve provided by the invention contain abundant crystal boundaries, and the crystal boundaries not only strengthen mass transfer diffusion of reactants 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-silicon molecular sieve provided by the invention is 1-5nm, 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 1 to 3nm and a grain boundary mesopore volume of 0.1 to 0.2 mL/g.
According to a preferred embodiment of the present invention, the molecular sieve has a micropore volume of from 0.15 to 0.18 mL/g.
In the present invention, the grain boundaries refer to interfaces between grains having the same structure but different orientations, and the contact interfaces between the grains are called grain boundaries. The grain boundary size refers to the distance between crystal grains, and is obtained by transmission electron microscope detection (measured by a TEM scale).
The tin-silicon 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 1nm 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 Lewis acid content of the tin-silicon molecular sieve is 200-300. mu. mol/g, and more preferably 230-290. 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 benzene adsorption amount measured under the condition of adsorption time of 1 hour is at least 30 mg/g, preferably 30 to 40 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. Under the same tin-silicon ratio, the acid amount and the acid strength of the tin-silicon molecular sieve provided by the invention are higher than those of the tin-silicon 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 second aspect, the present invention provides a method for preparing a tin-silicon molecular sieve, the method comprising:
(1) mixing a first liquid tin source, a first 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) heating the aged gel and the solid silicon source to obtain solid gel;
(4) roasting the solid gel to obtain tin silicon oxide;
(5) and mixing the tin-silicon oxide, the template agent, the second liquid tin source, the second liquid silicon source, water and the inorganic ammonium source to obtain a second mixture, and then crystallizing.
In the present invention, the auxiliary in the step (1) is not particularly limited. Preferably, the adjuvant comprises a space filler and/or a stabilizer.
Preferably, the space-filling agent is selected from a silylation agent and/or a water-soluble polymer compound, and more preferably a water-soluble polymer. More preferably, the silylating agent is selected from at least one of trimethylchlorosilane, t-butyldimethylchlorosilane, dimethyldiacetoxysilane, N-phenyl-3-aminopropyltrimethoxysilane and di-t-butyldichlorosilane; the water-soluble high molecular compound is polyacrylamide and/or polyacrylic acid. The weight average molecular weight of the water-soluble polymer compound may be 1000-100000.
Preferably, the stabilizer is selected from at least one of oxalic acid, t-butyl hydroperoxide, cyclohexyl hydroperoxide, hydrogen peroxide and citric acid.
Preferably, the molar ratio of the auxiliary agent to the first liquid silicon source in step (1) is 0.01-0.1: 1, preferably 0.02 to 0.07: 1, wherein the first liquid silicon source is SiO2And (6) counting.
In the present invention, the first liquid tin source in the step (1) and the second liquid tin source in the step (5) are not particularly limited. In particular, the first and second liquid tin sources are each independently selected from an inorganic liquid tin source and/or an organic liquid tin source.
According to a preferred embodiment of the present invention, the inorganic liquid tin source is selected from at least one of tin tetrachloride, tin dichloride, tin sulfate and tin oxysulfate, preferably tin tetrachloride and/or tin oxysulfate.
According to a preferred embodiment of the invention, the organic liquid tin source is selected from organic acid salts and/or stannates of tin, preferably stannates, selected from at least one of tetramethyl stannate, tetraethyl stannate, tetrapropyl stannate and tetrabutyl stannate, preferably tetraethyl stannate.
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 the present invention, preferably, SnO is used in the step (1)2Metering a first liquid tin source and SnO in step (5)2The molar ratio of the second liquid tin source is 1: 0.1 to 10, preferably 1: 0.5-2.
In the present invention, the first liquid silicon source in step (1) and the second liquid silicon source in step (5) are not particularly limited. In particular, the first and second liquid silicon sources are each independently selected from an inorganic liquid silicon source and/or an organic liquid silicon source.
According to a preferred embodiment of the present invention, the inorganic liquid silicon source is selected from at least one of silicon tetrachloride, sodium silicate and sodium metasilicate, preferably silicon tetrachloride.
Preferably, the organic liquid silicon source 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, 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 tetrapropyl silicate.
According to the invention, step (1) is preferably carried out with SiO2The first liquid silicon source and SiO in step (5)2The molar ratio of the second liquid silicon source is 1: 0.1 to 10, preferably 1: 0.5-2.
According to the invention, the molar ratio of the total tin source to the total silicon source is preferably between 0.005 and 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, wherein the total tin source is SnO2The total silicon source is SiO2The total tin source is SnO2A first liquid tin source and SnO2The sum of the second liquid tin source and the total silicon source is SiO2First liquid silicon source in terms of SiO2Second liquid silicon source and SiO2The sum of the calculated solid silicon sources.
Preferably in SiO2The total liquid silicon source and SiO in step (3)2The molar ratio of the solid silicon source is 1: 1-9, preferably 1: 2-8. 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 crystallized product of the tin-silicon molecular sieve can be improved, thereby improving the yield of single synthesis under the condition that a synthesis reaction kettle is not changed.
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 first liquid tin source, the first liquid silicon source and the auxiliary agent may be 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 embodiment of mixing in step (1) in the present invention is not particularly limited, as long as the first liquid tin source, the first liquid silicon source, the auxiliary agent and the solvent are uniformly mixed. Preferably, the mixing is carried out under stirring conditions, for example in a magnetic stirrer, for a period of time ranging from 1 to 20 hours.
According to the invention, the aging conditions are selected in a wide range, and preferably, the aging conditions in step (2) include: the aging temperature is 20-65 ℃, preferably 20-50 ℃; the aging time is 1 to 60 hours, preferably 2 to 50 hours, more preferably 3 to 30 hours, for example 3 to 15 hours.
According to a specific embodiment of the present invention, the aging in step (2) refers to allowing the first mixture in step (1) to stand at 20-65 ℃ for 1-60 hours, wherein the aging process preferably does not require stirring, and the first mixture is allowed to stand under the aging conditions.
According to the present invention, the heating conditions are selected in a wide range, and preferably, the heating conditions in step (3) include: under the closed condition, the heating temperature is 50-500 ℃, and preferably 250-500 ℃; the heating time is 1 to 30 hours, preferably 1 to 20 hours.
According to a specific embodiment of the present invention, the heating in step (3) refers to heating the aged sol and the solid silicon source in step (2) at 50-500 ℃ for 1-30 hours, so that the aged sol is completely converted into a solid gel, wherein the heating may be performed in a closed autoclave, which is not described herein in detail.
According to a preferred embodiment of the present invention, before the solid gel is calcined in step (4), the solid gel is further 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: in an oxygen-containing atmosphere, 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 oxygen-containing atmosphere is not particularly limited, and it is sufficient that only oxygen required for calcination can be supplied, and it may be pure oxygen or a mixed gas of oxygen and other gases.
In the present invention, the template in the step (5) is not particularly limited. The appropriate template can be selected according to the structure of the desired synthesized molecular sieve (MFI structure, MEL structure, BEA structure, MWW structure or MOR structure). Preferably, the template is selected from at least one of an organic quaternary ammonium compound, a long-chain alkyl ammonium compound and an organic amine, and further preferably, the template comprises the organic quaternary ammonium compound, the long-chain alkyl ammonium compound and optionally the organic amine.
Preferably, the organic quaternary ammonium compound is an organic quaternary ammonium base and/or an organic quaternary ammonium salt. Further preferably, the organic quaternary ammonium base is selected from at least one of tetrapropylammonium hydroxide, tetrabutylammonium hydroxide and tetraethylammonium hydroxide, and the organic quaternary ammonium salt is selected from at least one of tetrapropylammonium bromide, tetrabutylammonium bromide, tetraethylammonium bromide, tetrapropylammonium chloride, tetrabutylammonium chloride and tetraethylammonium chloride.
According to a preferred embodiment of the present invention, the tin-silicon 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-silicon 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-silicon 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 small-grain stacked tin-silicon molecular sieve can be synthesized under high solid content, so that the using amount of water is reduced, the single-kettle yield is improved, namely more molecular sieves are synthesized under the same synthesis reactor volume, and the molar ratio of the water to the total silicon source in the step (5) is preferably 5-80: 1 or 5-50: 1 or 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 first liquid tin 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 tin source is SnO2And (6) counting.
In the present invention, the inorganic ammonium source in the step (5) is not particularly limited. In particular, the inorganic ammonium source is selected from inorganic ammonium salts and/or aqueous ammonia, preferably aqueous ammonia. The inorganic ammonium salt is preferably at least one selected from the group consisting of ammonium chloride, ammonium nitrate and ammonium sulfate.
In the invention, the inorganic ammonium source is added, so that the oxidation activity of the tin-silicon molecular sieve is improved, the utilization rate of the tin source (higher framework tin-silicon ratio under the condition of the same tin source usage) is improved, and the usage amount of the tin source is reduced.
In the present invention, the crystallization is not particularly limited. Preferably, the crystallization conditions in step (5) include: the crystallization temperature is 110-200 ℃, preferably 140-180 ℃, and further preferably 160-180 ℃; the crystallization pressure is autogenous pressure, and the crystallization time is 2 to 480 hours, preferably 0.5 to 10 days, for example, 1 to 6 days, and more preferably 1 to 3 days.
According to one embodiment of the invention, the crystallization may be carried out in a stainless steel stirred tank. The temperature rise for crystallization can be carried out in a one-stage temperature rise manner or a multi-stage temperature rise manner, and the temperature rise rate can be carried out according to the existing crystallization temperature rise method, for example, 0.5-1 ℃/min.
According to a preferred embodiment of the present invention, the crystallization conditions include: crystallizing at 100-.
According to the invention, the method can also comprise recovering the tin-silicon molecular sieve from the product obtained by crystallization in the step (5). The method for recovering the tin-silicon 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 small-grained stacked tin-silicon molecular sieve 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, and for example, the mixed washing can be carried out 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 the filtration or the rinsing with water is carried out. 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-silicon molecular sieve provided by the invention is obtained by recovery.
According to the invention, preferably, the method further comprises a step (6), said step (6) comprising: and (4) mixing the solid product obtained in the step (5), organic base and water, and then carrying out second crystallization.
Preferably, the conditions of the second crystallization include: the second crystallization temperature is 110-200 ℃, more preferably 150-200 ℃; the second crystallization time is 0.5 to 10 days, more preferably 1 to 8 days.
According to a preferred embodiment of the present invention, the solid product obtained in step (5), an organic base and water are mixed and subjected to a second crystallization. The obtained small-grain stacked tin-silicon 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 the tin-silicon molecular sieve from the product obtained by crystallization in the step (6). Generally comprises filtering, washing, drying and then roasting the crystallized product, and the recovery method can be referred to the step (5), and the invention is not described herein.
In the present invention, the rearrangement of the molecular sieve step (6) may be performed once or may be repeated a plurality of times. The rearranged tin-silicon molecular sieve with more obvious mesoporous structure and stacked small crystal grains is obtained through rearrangement treatment, and the rearranged tin-silicon molecular sieve has larger pore volume and specific surface area.
In a third aspect, the invention provides a cyclohexanone oximation reaction method, which comprises contacting cyclohexanone, ammonia and hydrogen peroxide with the tin-silicon molecular sieve provided by the invention under oximation reaction conditions.
The cyclohexanone oximation reaction method according to the present invention is not particularly limited in the oximation reaction conditions, and 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 source
Tube 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 acidity, acid strength and acid content of the tin-silicon molecular sieve are measured by pyridine adsorption infrared spectroscopy.
The particle size of the molecular sieve particles and the particle size of the crystal grains of the tin-silicon molecular sieve are obtained by transmission electron microscope detection (measured by a TEM scale).
In the following examples, room temperature was 25 ℃ unless otherwise specified.
The sources of the raw materials used in the examples and comparative examples are as follows:
tetrabutyl stannate, analytically pure, chemical reagents of national drug group, ltd.
Tin tetrachloride, analytically pure, chemical reagents of the national drug group, ltd.
Tetrapropylammonium hydroxide, available from Guangdong chemical plant.
Tetraethyl silicate, analytically pure, chemical reagents of the national pharmaceutical group, ltd.
Ammonia, analytically pure, concentration 20% by weight.
White carbon black, Zhejiang Juhua group product, model AS-150; the solid content is more than 95 wt%, the silicon dioxide content in dry basis is more than 99.99 wt%, the total content of iron, sodium and Al 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 purchased from Agilent company and is model 6890, and the analytical chromatographic column is an FFAP column.
Examples 1 to 12 of the present invention are made of SiO2The total silicon source usage was fixed at 0.2 mol.
Example 1
(1) Tetrabutyl stannate (a first liquid tin source), tetraethyl silicate (TEOS, a first liquid silicon source), polyacrylic acid (weight average molecular weight of 5000) powder and 3g of water are sequentially added into a 500mL beaker, put on a magnetic stirrer with heating and stirring functions, and are uniformly mixed, and stirred at room temperature for 4 hours to obtain a first mixture.
(2) And standing the first mixture at room temperature for 12 hours for aging treatment to obtain an aged sol.
(3) Adding white carbon black powder (solid silicon source) into the aged sol under stirring, and heating in a closed autoclave at 500 ℃ for 5 hours to obtain solid gel.
(4) Washing the solid gel with deionized water for 3 times, and roasting in a muffle furnace at 500 ℃ for 5 hours to obtain SnO2-SiO2White oxide.
(5) Mixing the tin-silicon oxide, 25.05 wt% tetrapropylammonium hydroxide aqueous solution (TPAOH), hexadecyltrimethylammonium hydroxide (MSDS), tetrabutyl stannate (a second liquid tin source), tetraethyl silicate (TEOS, a second liquid silicon source), 20 wt% ammonia water and water to obtain a second mixture, then transferring the second mixture into a stainless steel closed reaction kettle, crystallizing at the constant temperature of 175 ℃ for 48 hours 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 tin-silicon molecular sieve S-1 with an MFI structure.
SEM and TEM photographs of the tin-silicon molecular sieve S-1 are shown in figures 1 and 2, and an 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, benzene adsorption amount and Lewis acid amount of the molecular sieve are shown in Table 2.
Example 2
(1) Tin tetrachloride, tetraethyl silicate (TEOS), tert-butyl hydroperoxide and 10g of ethanol are sequentially added into a 500mL beaker, placed on a magnetic stirrer with heating and stirring functions, mixed uniformly and stirred at room temperature for 10 hours to obtain a first mixture.
(2) And standing the first mixture at 37 ℃ for 24 hours for aging treatment to obtain an aged sol.
(3) Adding white carbon black powder into the aged sol under stirring, and heating in a sealed autoclave at 450 ℃ for 4 hours to obtain solid gel.
(4) Washing the solid gel with deionized water for 3 times, and standing at 450 deg.CRoasting in a muffle furnace for 4 hours to obtain SnO2-SiO2White oxide.
(5) Mixing the tin silicon oxide, 25.05 weight percent tetrapropylammonium hydroxide aqueous solution (TPAOH), hexadecyltrimethylammonium hydroxide (MSDS), tetrabutyl stannate, tetraethyl silicate (TEOS), 20 weight percent ammonia water and water to obtain a second mixture, then transferring the second mixture into a stainless steel closed reaction kettle, crystallizing at the constant temperature of 160 ℃ for 72 hours to obtain a crystallized sample, filtering and washing the crystallized sample, drying the crystallized sample at 120 ℃ for 24 hours, and roasting the crystallized sample at 550 ℃ for 6 hours to obtain the small-grain stacked tin silicon molecular sieve S-2 with an MFI structure.
The SEM image and the TEM image of the tin-silicon molecular sieve S-2 are similar to those of the tin-silicon molecular sieve S-1, and an 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, benzene adsorption amount and Lewis acid amount of the molecular sieve are shown in Table 2.
Example 3
Taking the tin-silicon molecular sieve S-2 prepared in example 2 as a matrix, mixing 6g of the sample with 22.05 weight percent of TPAOH aqueous solution, uniformly stirring, crystallizing at 150 ℃ for 3 days in a closed reaction kettle, filtering, washing, drying at 120 ℃ for 24 hours, and roasting at 550 ℃ for 6 hours to obtain the tin-silicon molecular sieve S-3 with hollow small-grain stacking shape and an MFI structure.
The TEM photograph of the tin-silicon molecular sieve S-3 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, benzene adsorption amount and Lewis acid amount of the molecular sieve are shown in Table 2.
Examples 4 to 7
Tin-silicon molecular sieves were prepared according to the method of example 1, and the compositions and synthesis conditions of the tin-silicon molecular sieves are shown in table 1, to obtain small-grained stacked tin-silicon 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, benzene adsorption amount and Lewis acid amount of the molecular sieve are shown in Table 2.
Example 8
The method of example 1 was followed except that in step (5), first, crystallization was carried out at 120 ℃ for 1 day, and then at 170 ℃ for 2 days, and the composition and synthesis conditions of the tin-silicon molecular sieve are shown in table 1, thereby obtaining small-crystallite stacked tin-silicon molecular sieve 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, benzene adsorption amount and Lewis acid amount of the molecular sieve are shown in Table 2.
Example 9
Preparing a tin-silicon molecular sieve with an MEL structure. Referring to the method according to example 1, the composition and synthesis conditions of the tin-silicon molecular sieve are shown in table 1 by changing the mixture ratio and the template, and the small-grain stacked tin-silicon molecular sieve S-9 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, benzene adsorption amount and Lewis acid amount of the molecular sieve are shown in Table 2.
Example 10
Preparing the tin-silicon molecular sieve with the BEA structure. Referring to the method of example 1, the composition and synthesis conditions of the tin-silicon molecular sieve are shown in table 1 by changing the mixture ratio and the template, and the small-grain stacked tin-silicon molecular sieve S-10 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, 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 the aging temperature was 75 ℃ to obtain tin-silicon molecular sieve S-11. The average grain size of the molecular sieve grains, the average grain boundary size, are listed in table 2. 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, benzene adsorption amount and Lewis acid amount of the molecular sieve are shown in Table 2.
Example 12
The procedure of example 1 was followed, except that polyacrylic acid was replaced with an equimolar amount of trimethylchlorosilane, to obtain a tin-containing molecular sieve S-12. The average grain size of the molecular sieve grains, the average grain boundary size, are listed in table 2. 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, benzene adsorption amount and Lewis acid 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 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 moved into a stainless steel closed reaction kettle and crystallized for 3 days at the constant temperature of 170 ℃, thus obtaining the conventional tin-silicon molecular sieve D-1.
SEM and TEM photographs of the tin-silicon molecular sieve D-1 are shown in figures 4 and 5, 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, 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 moved into a stainless steel closed reaction kettle and crystallized for 3 days at the constant temperature of 170 ℃ to obtain the conventional tin-silicon 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-silicon molecular sieve, and preparing the tin-silicon 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 silicon molecular sieve D-2.
SEM and TEM photographs of the tin-silicon molecular sieve D-2 are shown in FIGS. 6 and 7, and an 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, 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 ammonia (anhydrous ammonium source) was added, tin-silicon 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, benzene adsorption amount and Lewis acid amount of the molecular sieve are shown in Table 2.
Comparative example 4
Following the procedure of example 1, except that no ammonia (anhydrous ammonium source) was added and no aging was performed, tin silicalite D-4 was obtained. The average particle size of the molecular sieve grains, the average particle size of the molecular sieve particles, and the average grain boundary size are shown in table 2. The micropore volume, mesopore volume, benzene adsorption amount and Lewis acid 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 give tin-silicon 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, benzene adsorption amount and Lewis acid amount of the molecular sieve are shown in Table 2.
Test example
The tin-silicon molecular sieves prepared in the above examples 1 to 12 and comparative examples 1 to 5 were used as catalysts for oximation reaction of cyclohexanone to carry out oximation reaction.
According to the tin-containing molecular sieve: tert-butanol (solvent): 25 wt% ammonia 1: 7.5: 7.5 mass ratio (wherein the weight of ammonia water is NH)3Metering) is evenly stirred and mixed in the slurry bed, the temperature is raised to 78 ℃, and the dosage of the tin-containing molecular sieve is 3 g. Then 30 weight percent hydrogen peroxide is added at the temperature at the rate of 6mL/h, a mixture of cyclohexanone and tert-butyl alcohol is added at the rate of 8.6mL/h (the volume ratio of the cyclohexanone to the tert-butyl alcohol is 1: 2.5), and simultaneously 25 weight percent ammonia water solution is added at the rate of 6mL/h, 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:
from the data in table 2, it can be seen that the tin-silicon molecular sieve of the present invention has larger particle size, grain boundary size, Lewis acid amount and benzene adsorption amount than the existing tin-silicon molecular sieve. The tin-silicon 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.
Claims (14)
1. The tin-silicon molecular sieve is characterized in that the molecular sieve particles are formed by stacking crystal grains with the particle size of 20-50nm, the particle size of the molecular sieve particles is 500-1000nm, the average grain boundary size of the molecular sieve particles is 1-5nm, the grain boundary mesoporous volume is 0.1-0.5mL/g, and the Lewis acid weight of the molecular sieve is 200-300 mu mol/g.
2. The molecular sieve of claim 1, wherein the molecular sieve has a tin-to-silicon molar ratio of 0.005-0.04: 1, preferably 0.01-0.035: 1;
preferably, the average grain boundary size of the molecular sieve particles is 1-3nm, and the mesoporous volume of the grain boundary is 0.1-0.2 mL/g.
3. The molecular sieve of claim 1, wherein the molecular sieve is at 25 ℃, P/P0An adsorbed amount of benzene of at least 30 mg/g, preferably 30 to 40 mg/g, as measured under the condition of an adsorption time of 1 hour, 0.1;
preferably, the molecular sieve has an MFI structure, an MEL structure, a BEA structure, an MWW structure or an MOR structure.
4. A method of making a tin-silicon molecular sieve, the method comprising:
(1) mixing a first liquid tin source, a first 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) heating the aged gel and the solid silicon source to obtain solid gel;
(4) roasting the solid gel to obtain tin silicon oxide;
(5) and mixing the tin-silicon oxide, the template agent, the second liquid tin source, the second liquid silicon source, water and the inorganic ammonium source to obtain a second mixture, and then crystallizing.
5. The production method according to claim 4, wherein the auxiliary in step (1) comprises a space-filling agent and/or a stabilizer;
preferably, the space-filling agent is selected from a silylating agent and/or a water-soluble polymer 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;
preferably, the molar ratio of the auxiliary agent to the first liquid silicon source in step (1) is 0.01-0.1: 1, preferably 0.02 to 0.07: 1, wherein the first liquid silicon source is SiO2And (6) counting.
6. The production method according to claim 4, wherein the first and second liquid tin sources are each independently selected from an inorganic liquid tin source and/or an organic liquid tin source;
preferably, the first and second liquid silicon sources are each independently selected from an inorganic liquid silicon source and/or an organic liquid silicon source;
preferably, the solid silicon source in the step (3) is white carbon black and/or silica gel;
preferably, SnO is used in step (1)2Metering a first liquid tin source and SnO in step (5)2The molar ratio of the second liquid tin source is 1: 0.1 to 10, preferably 1: 0.5 to 2;
preferably, SiO is used in step (1)2Of metersThe first liquid silicon source and SiO in step (5)2The molar ratio of the second liquid silicon source is 1: 0.1 to 10, preferably 1: 0.5 to 2;
preferably, the molar ratio of the total tin source to the total silicon source is 0.005-0.05: 1, wherein the total tin source is SnO2The total silicon source is SiO2The total tin source is SnO2A first liquid tin source and SnO2The sum of the second liquid tin source and the total silicon source is SiO2First liquid silicon source in terms of SiO2Second liquid silicon source and SiO2The sum of the counted solid silicon sources;
preferably in SiO2The total liquid silicon source and SiO in step (3)2The molar ratio of the solid silicon source is 1: 1-9, preferably 1: 2-8.
7. The production method according to claim 4, wherein the aging conditions in step (2) include: the aging temperature is 20-65 ℃, preferably 20-50 ℃; the aging time is 1 to 60 hours, preferably 2 to 50 hours;
preferably, the heating conditions in step (3) include: under the closed condition, the heating temperature is 50-500 ℃, and preferably 250-500 ℃; the heating time is 1 to 30 hours, preferably 1 to 20 hours;
preferably, the roasting conditions in step (4) include: in an oxygen-containing atmosphere, the roasting temperature is 100-500 ℃, and preferably 250-480 ℃; the calcination time is 1 to 20 hours, preferably 2 to 10 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 5 to 30: 1;
preferably, the molar ratio of the inorganic ammonium source in step (5) to the first liquid tin 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 first liquid tin source is SnO2And (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 tin-silicon molecular sieve prepared by the preparation method of any one of claims 4 to 12.
14. A cyclohexanone oximation reaction method, comprising contacting cyclohexanone, ammonia and hydrogen peroxide with a tin-silicon molecular sieve under oximation reaction conditions, wherein the tin-silicon molecular sieve is the tin-silicon molecular sieve defined in any one of claims 1-3 and 13.
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