CN114031094B - Nano MFI/MOR eutectic molecular sieve and synthesis method of nano Ti-MFI/MOR eutectic molecular sieve - Google Patents
Nano MFI/MOR eutectic molecular sieve and synthesis method of nano Ti-MFI/MOR eutectic molecular sieve Download PDFInfo
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Abstract
The invention relates to a method for synthesizing a nano MFI/MOR eutectic molecular sieve and a nano Ti-MFI/MOR eutectic molecular sieve, which comprises the steps of (1) mixing a silicon source, a template agent and water, aging, and performing hydrothermal crystallization to obtain zeolite seed crystals; (2) Mixing a silicon source, an aluminum source, an alkali source and water to form sol, adding zeolite seed crystals, aging, carrying out hydrothermal crystallization, carrying out solid-liquid separation on crystallized mother liquor, washing, drying and roasting to obtain the nano MFI/MOR eutectic molecular sieve. The nanometer MFI/MOR eutectic molecular sieve is subjected to acid washing, water washing, drying and roasting to obtain a dealuminated nanometer MFI/MOR eutectic molecular sieve; and carrying out gas-solid phase isomorphous substitution on the dealuminated nano MFI/MOR eutectic molecular sieve and titanium tetrachloride to obtain the nano Ti-MFI/MOR eutectic molecular sieve. The nano Ti-MFI/MOR eutectic molecular sieve synthesized by the method has low cost and small grain size (60-190 nm), shows excellent catalytic performance in the reactions of catalyzing cyclohexanone ammoxidation to prepare cyclohexanone oxime and phenol hydroxylation to prepare benzenediol, and has great industrial application potential.
Description
Technical Field
The invention belongs to the technical field of molecular sieve synthesis, and particularly relates to a method for synthesizing a nano MFI/MOR eutectic molecular sieve and a nano Ti-MFI/MOR eutectic molecular sieve.
Background
Titanium silicalite molecular sieve (TS-1) is a titanium (Ti) containing heteroatom molecular sieve, and its synthesis method was first reported in 1983 in U.S. Pat. No. 4,4410501. Ti atoms on the TS-1 zeolite molecular sieve replace silicon or aluminum atoms in a zeolite molecular sieve framework to form tetradentate framework titanium, so that the TS-1 zeolite molecular sieve has excellent selective oxidation activity. The oxidation system composed of the TS-1 zeolite molecular sieve and hydrogen peroxide shows good application prospects in the aspects of olefin oxidation, aromatic hydrocarbon hydroxylation, ketone ammoxidation, alkane partial oxidation, alcohol selective oxidation and the like. In addition, a Ti-MOR zeolite molecular sieve containing heteroatom Ti can also be obtained if Ti atoms are implanted into the mordenite molecular sieve (MOR) framework in an isolated four-coordinate state. Compared with the TS-1 zeolite molecular sieve, the Ti-MOR zeolite molecular sieve has more excellent performance in catalyzing selective oxidation reaction, especially ketone oximation reaction.
The TS-1 zeolite molecular sieve has an MFI topological structure, the MFI structure comprises 2 intercrossed channel structures, one is a straight channel parallel to a b axis, an oval hole consists of ten-membered rings, and the hole diameter is 0.53 multiplied by 0.56nm; the other is a zigzag channel parallel to the c axis, and the round orifice is composed of ten-membered rings and has a pore diameter of 0.51nm. The Ti-MOR zeolite molecular sieve has one-dimensional 12-membered ring channel (pore size of 0.65X 0.70 nm) and one 8-membered ring channel (pore size of 0.26X 0.57 nm) growing along the c-axis and one 8-membered ring channel (pore size of 0.34X 0.48 nm) growing along the b-axis. Due to the narrow pore size of the TS-1 and Ti-MOR zeolite molecular sieves, reactant molecules with large kinetic diameters are limited to enter zeolite pore channels to contact with active centers for action, so that the conversion rate of raw materials is reduced; on the other hand, the narrow pore size also limits the diffusion of product molecules with larger kinetic diameters out of the zeolite pore channels, which in turn leads to rapid deactivation of the catalyst. Finding a method capable of solving the defects of the titanium silicalite molecular sieve has very important significance for the industrial application of the titanium silicalite molecular sieve.
One of the effective methods to solve the above problems is to synthesize a zeolite molecular sieve of TS-1 or Ti-MOR having a smaller grain size. The smaller grain size reduces the length of the zeolite molecular sieve pore channel, and is beneficial to the diffusion of reactant molecules and product molecules, thereby improving the conversion rate of raw materials and the stability of the catalyst. A number of patents and articles disclose the synthesis and catalytic performance of smaller crystallite size TS-1 or Ti-MOR zeolite molecular sieves. For example: patent CN109250726B discloses a preparation method of a cheap small-size titanium Silicalite TS-1, which does not need to add organic template agent, and can synthesize a cheap small-size TS-1 molecular sieve by using non-calcined or incompletely calcined non-porous or small-porous whole Silicalite-1 powder or its synthesis mother liquor as seed crystal and controlling appropriate alkali-silica ratio, water-silica ratio and seed crystal addition amount. The crystallinity is high, the grain size range is 50-300nm, titanium species can be uniformly distributed in the TS-1 molecular sieve, and the catalytic activity and stability of propylene epoxidation reaction are high. Patent 107539999A discloses a titanium-silicon molecular sieve and its preparation method and application, said titanium-silicon molecular sieve is formed from nano-scale hollow crystal particles whose grain size is 10-150nm, and the maximum diameter of cavity of nano-scale hollow crystal particles is above 2nm, and said invented titanium-silicon molecular sieve is formed from small crystal particles, and its crystal particles are formed from small crystal particles, and said aggregated crystal particles are good in stability, can not be redispersed in the course of use, and its mechanical strength is high, and its stability in inorganic alkaline solution is good. The article Journal of Catalysis,325, (2015), 101-110 discloses a method for synthesizing a Ti-MOR zeolite catalyst, which researches the catalytic performance of Ti-MOR zeolite catalysts with different grain sizes. Research shows that small particle MOR, especially on nano-scale grains, is easier to react with TiCl 4 The vapor gas-solid phase isomorphous substitution forms a four-coordination framework titanium species, the physical and chemical properties and the catalytic performance of the Ti-MOR zeolite molecular sieve and the crystal length of the Ti-MOR zeolite molecular sieve show regular changes, and the smaller the particle size, the higher the catalytic performance.
The above patent technologies and articles provide a synthesis method of titanium silicalite molecular sieve with smaller grain size, and simultaneously illustrate the influence of the grain size on the catalytic performance of the reaction. However, the above patent techniques and articles have been studied only on a single TS-1 titanium silicalite molecular sieve or a single Ti-MOR titanium silicalite molecular sieve. And the research on the synthesis method and the catalytic performance of the eutectic Ti-MFI/MOR molecular sieve which has two topological structures of MFI and MOR, in particular the nano Ti-MFI/MOR eutectic molecular sieve is less.
Disclosure of Invention
According to one aspect of the application, a method for synthesizing a nano MFI/MOR eutectic molecular sieve is provided; on the other hand, the method for synthesizing the nano Ti-MFI/MOR eutectic (titanium silicon) molecular sieve has the advantages of low cost and small grain size (60-190 nm), and shows excellent catalytic performance in the reactions of catalyzing cyclohexanone to be subjected to ammoxidation to prepare cyclohexanone oxime and preparing hydroquinone through phenol hydroxylation.
The technical scheme of the invention is as follows:
a method for synthesizing a nano MFI/MOR eutectic molecular sieve comprises the following steps:
(1) Mixing a silicon source, a template agent R and water, stirring at normal temperature and aging to obtain a mixture 1; carrying out hydrothermal crystallization on the mixture 1 at the temperature of 130-180 ℃ for 6-168 h to obtain zeolite seed crystals;
(2) Mixing a silicon source, an aluminum source, an alkali source and water to form a sol, and adding zeolite seed crystals (in SiO) to the sol 2 Based on the mass of) the mass added is the silicon source (in SiO) in step (2) 2 In mass) of 1 to 80wt%, stirring and aging at normal temperature to obtain a mixture 2; and (3) carrying out hydrothermal crystallization on the mixture 2 at 130-200 ℃ for 6-168 hours, and carrying out solid-liquid separation, washing, drying and roasting on crystallized mother liquor to obtain the nano MFI/MOR eutectic molecular sieve.
Preferably, the zeolite seeds (in SiO) in step (2) 2 By mass of) the silicon source (in terms of SiO) added in the step (2) 2 Based on the mass) is added to account for 1 to 60 weight percent of the mass; further, the zeolite seeds (in SiO) 2 Based on the mass of) adding a silicon source (in terms of SiO) in the mass of step (2) 2 Based on the mass) of 1 to 30wt% of the added mass.
Preferably, in the step (1), the molar ratio of the materials in the mixture 1 is as follows: R/SiO 2 ＝0.01～1.0，H 2 O/SiO 2 And the molar ratio of the materials in the mixture 1 is as follows: R/SiO 2 ＝0.05～0.6，H 2 O/SiO 2 And (5) = 15-60. The mole number of the silicon source in the mixture 1 is SiO 2 In moles of template R as the moles of its corresponding template, H 2 The number of moles of O is in terms of its own number of moles.
Preferably, the molar ratio of the materials in the sol in the step (2) is as follows: siO 2 2 /Al 2 O 3 ＝6～100，M 2 O/SiO 2 M is alkali metal in alkali source, H is 0.15-2.0 2 O/SiO 2 = 10-100, and the molar ratio of the materials in the sol is: siO 2 2 /Al 2 O 3 ＝10～30，M 2 O/SiO 2 ＝0.15～1.0，H 2 O/SiO 2 And (5) = 15-60. The mol number of the silicon source in the sol is SiO 2 In moles of the alkali source, in M 2 Mole number of O, H 2 Mole number of OIn moles on its own.
Preferably, the silicon source in step (1) is an inorganic silicon source and/or an organic silicon source, further, the silicon source is one or more of white carbon black, silica sol, tetraethoxysilane and methyl orthosilicate, and further, the silicon source is one or more of silica sol, tetraethoxysilane and methyl orthosilicate; preferably, the template agent R is one or more of n-butylamine, ethanolamine, diethanolamine, triethanolamine, ethylenediamine, hexamethylenediamine, diethylamine, tetrapropylammonium bromide and tetrapropylammonium hydroxide, and further, the template agent R is one or more of n-butylamine, ethanolamine, tetrapropylammonium bromide and tetrapropylammonium hydroxide.
Preferably, in the step (1), the silicon source, the template agent R and the water are mixed, stirred at normal temperature and aged to obtain the mixture 1, and the concrete steps of the mixture 1 are as follows: adding a template agent R into water for dissolving to obtain the aqueous solution containing the template agent R; and adding a silicon source into the aqueous solution containing the template agent R under the stirring condition, stirring, and continuing stirring at normal temperature for aging to obtain a mixture 1.
The normal-temperature stirring and aging time in the step (1) is preferably 1 to 24 hours, and further preferably 3 to 12 hours.
Preferably, the hydrothermal crystallization in the step (1) is dynamic crystallization; the crystallization temperature is 130-160 ℃; the crystallization time is 12-96 h.
Preferably, in the step (2), the specific steps of mixing the silicon source, the aluminum source, the alkali source and the water to obtain the sol are as follows: adding an alkali source into water, and stirring for dissolving; adding an aluminum source, and stirring for dissolving; adding a silicon source to obtain the sol.
Preferably, in the step (2), the silicon source is one or more of water glass, silica sol, white carbon black, ethyl orthosilicate and methyl orthosilicate; the alkali source is one or more of sodium hydroxide and potassium hydroxide, and the aluminum source is one or more of aluminum sulfate, sodium aluminate, aluminum nitrate and aluminum isopropoxide; further, the silicon source is one or more of ethyl orthosilicate and methyl orthosilicate; further, the alkali source is sodium hydroxide; the aluminum source is sodium aluminate.
Preferably, the normal-temperature stirring and aging time in the step (2) is 1 to 24 hours, preferably 3 to 12 hours;
preferably, the hydrothermal crystallization in the step (2) is dynamic crystallization; the crystallization temperature is 130-160 ℃; the crystallization time is 12-96 h.
Preferably, the drying temperature in the step (2) is 50 to 150 ℃, further 100 to 130 ℃, and the baking temperature is 300 to 600 ℃, further 450 to 550 ℃.
The invention also provides a synthesis method of the nano Ti-MFI/MOR eutectic molecular sieve, which comprises the following steps: the nanometer MFI/MOR eutectic molecular sieve is subjected to acid washing, water washing, drying and roasting to obtain a dealuminated nanometer MFI/MOR eutectic molecular sieve; and carrying out gas-solid phase isomorphous substitution on the dealuminated nano MFI/MOR eutectic molecular sieve and titanium tetrachloride to obtain the nano Ti-MFI/MOR eutectic molecular sieve.
The Ti-MFI/MOR eutectic molecular sieve is nano-sized, and the grain size is 60-190 nm.
Preferably, in the step (3), the acid for pickling is one or more of nitric acid, sulfuric acid, hydrochloric acid, perchloric acid, hydroiodic acid, hydrobromic acid and citric acid, and further is nitric acid or sulfuric acid; the acid concentration is 0.6-6 mol/L, the liquid-solid ratio is = 1-30: 1, further, the liquid-solid ratio is 3-15: 1.
preferably, the molar ratio of silicon-aluminum oxide to aluminum-silicon oxide of the nano MFI/MOR eutectic molecular sieve subjected to dealumination in the step (3) is SiO 2 /Al 2 O 3 ≥150。
Preferably, the reaction temperature of gas-solid phase isomorphous substitution in the step (3) is 300-600 ℃, the isomorphous substitution reaction time is 2-24 h, and further, the isomorphous substitution reaction temperature is 350-550 ℃; the isomorphous substitution reaction time is 2-12 h.
The beneficial effects of the invention include:
1) The application provides a method for synthesizing a nano MFI/MOR eutectic molecular sieve, and provides a method for synthesizing a nano Ti-MFI/MOR eutectic molecular sieve for the first time; in the synthesis method, the synthesis raw materials of the nano MFI/MOR eutectic molecular sieve and the nano Ti-MFI/MOR eutectic molecular sieve are cheap and easy to obtain, and the synthesis cost is low;
2) The nano Ti-MFI/MOR eutectic molecular sieve synthesized by the method has small grain size (60-190 nm), has a unique pore channel structure generated by structural distortion, and shows excellent catalytic performance in the reactions of preparing cyclohexanone oxime by catalyzing cyclohexanone ammoxidation and preparing benzenediol by phenol hydroxylation.
Drawings
FIG. 1 is an X-ray powder diffraction pattern (XRD) of sample # 1;
FIG. 2 is a Scanning Electron Micrograph (SEM) of sample # 1.
Detailed Description
The present application will be described in detail with reference to examples, but the present application is not limited to these examples.
The raw materials in the examples of the present application were all purchased commercially, unless otherwise specified.
The analysis method in the examples of the present application is as follows:
x-ray powder diffraction phase analysis (XRD) an X-ray diffractometer of the type X' pert Pro from Panasonic (PANALYtic) in the Netherlands, cu target, voltage 40kV and current 40mA were used.
Scanning Electron Microscope (SEM) test A SUPRA55 SAPPHIRE scanning electron microscope, ZEISS, germany, was used at an acceleration voltage of 3kV.
Example 1: synthesis of MFI/MOR eutectic molecular sieves
Step (1): synthetic zeolite seed crystal
290g of deionized water and 210g of tetrapropylammonium hydroxide (25 wt%) are sequentially added into a plastic beaker, after being uniformly stirred, 150g of tetraethoxysilane is added under the stirring state, and then the mixture is stirred and aged for 3 hours at normal temperature to obtain a mixture 1, wherein the initial material composition of the mixture 1 is SiO 2 ：TPAOH：H 2 O =1:0.36:35 (molar ratio); and transferring the mixture 1 to a hydrothermal synthesis kettle, and crystallizing at 140 ℃ for 10 hours to obtain zeolite seed crystals.
Step (2): synthesis of MFI/MOR eutectic molecular sieves
462g of deionized water and 44.0g of sodium hydroxide are sequentially added into a plastic beaker, stirred uniformly, 18.0g of sodium aluminate is added under the stirring state, and after the mixture is stirred to be clear, 420g of silica sol (30 wt%) is added, wherein the composition of the sol is SiO 2 ：NaO 2 ：Al 2 O 3 ：H 2 O =1:0.3:0.04:20 (molar ratio), adding 95.0g of zeolite seed crystals synthesized in the step (1), and continuing stirring and aging for 3 hours to obtain a mixture 2; and (3) transferring the mixture 2 to a hydrothermal synthesis kettle, and crystallizing at 150 ℃ for 96h at the rotating speed of 30r/min. And (3) carrying out conventional suction filtration and washing on the crystallized product, drying at 110 ℃ for 12h, roasting at 500 ℃ for 4h, and roasting to obtain a solid product. The solid product is analyzed by XRD test, and the crystalline phase is MFI/MOR eutectic topological structure zeolite molecular sieve.
Example 2 Synthesis of Ti-MFI/MOR Zeolite molecular sieves
Taking 10g of MFI/MOR eutectic molecular sieve synthesized in example 1, and mixing the MFI/MOR eutectic molecular sieve with the solid-liquid ratio of 1: refluxing in 10 (6 ml/L) nitric acid aqueous solution for 10h, filtering and washing to neutrality, and drying at 80 ℃ for 12h to obtain a dealuminized sample; placing the sample in a quartz reaction tube, dehydrating and activating for 2h at 400 ℃ under the nitrogen atmosphere, introducing TiCl steam for treating for 4h, purging for 1h with nitrogen, cooling to room temperature, washing with deionized water, and drying for 12h at 110 ℃ to obtain a Ti-MFI/MOR eutectic molecular sieve sample, wherein the sample is marked as 1#, and the XRD peak of the 1# sample is shown in figure 1 and is an MFI and MOR eutectic topological structure; the SEM photograph is shown in FIG. 2, which shows that the obtained Ti-MFI/MOR zeolite has a molecular sieve size of 80-160nm, and the silicon-titanium ratio is 41 by XRF analysis.
EXAMPLE 3 Synthesis of Ti-MFI/MOR Zeolite molecular sieves
The raw materials and the synthesis steps are the same as those in example 2, except that the crystallization temperature in the step (1) for synthesizing the MFI/MOR eutectic molecular sieve is changed to 130 ℃, and a Ti-MFI/MOR zeolite molecular sieve sample is obtained and is marked as # 2. XRD test analysis shows that the crystalline phase is MFI/MOR eutectic molecular sieve; the molecular sieve of the Ti-MFI/MOR zeolite has the particle size of 60-110nm and the silicon-titanium ratio is 38 through XRF analysis.
Example 4 Synthesis of Ti-MFI/MOR Zeolite molecular sieves
The raw materials and the synthesis steps are the same as those in example 2, except that the crystallization temperature in the step (1) for synthesizing the MFI/MOR eutectic molecular sieve is changed to 150 ℃ to obtain a Ti-MFI/MOR zeolite molecular sieve sample, which is marked as # 3. XRD test analysis shows that the crystalline phase is MFI/MOR eutectic molecular sieve; the particle size of the Ti-MFI/MOR zeolite molecular sieve is 85-170nm by SEM characterization, and the silicon-titanium ratio is 43 by XRF analysis.
EXAMPLE 5 Synthesis of Ti-MFI/MOR Zeolite molecular sieves
The raw materials and the synthesis steps are the same as those in example 2, except that the crystallization temperature in the step (1) for synthesizing the MFI/MOR eutectic molecular sieve is changed to 160 ℃, and a Ti-MFI/MOR zeolite molecular sieve sample is obtained and is marked as No. 4. XRD test analysis shows that the crystalline phase is MFI/MOR eutectic molecular sieve; the particle size of the Ti-MFI/MOR zeolite molecular sieve is 100-180nm through SEM characterization, and the silicon-titanium ratio is 45 through XRF analysis.
Example 6 Synthesis of Ti-MFI/MOR Zeolite molecular sieves
The raw materials and the synthesis steps are the same as those in example 2, except that the amount of the zeolite crystal added in the step (2) for synthesizing the MFI/MOR eutectic molecular sieve is 47.5g, and a Ti-MFI/MOR zeolite molecular sieve sample is obtained and is marked as # 5. XRD test analysis shows that the crystalline phase is MFI/MOR eutectic molecular sieve; the particle size of the Ti-MFI/MOR zeolite molecular sieve is 130-190nm by SEM characterization, and the silicon-titanium ratio is 42 by XRF analysis.
Example 7 Synthesis of Ti-MFI/MOR Zeolite molecular sieves
The raw materials and the synthesis steps are the same as those in example 2, except that the amount of the zeolite crystals added in the step (2) for synthesizing the MFI/MOR eutectic molecular sieve is 142.5g, and a Ti-MFI/MOR zeolite molecular sieve sample is obtained and is marked as No. 6. XRD test and analysis show that the crystalline phase is MFI/MOR eutectic molecular sieve; the particle size of the Ti-MFI/MOR zeolite molecular sieve is 60-100nm through SEM characterization, and the silicon-titanium ratio is 36 through XRF analysis.
COMPARATIVE EXAMPLE 1 (not in accordance with the invention)
The starting materials and synthesis steps were the same as in example 2, except that no seed was added in step (2) of synthesizing the MFI/MOR eutectic molecular sieve. And (4) synthesizing to obtain a Ti-MOR zeolite molecular sieve sample marked as No. 7. XRD test analysis shows that the crystalline phase is MOR topological structure; the particle size of the Ti-/MOR zeolite molecular sieve is 400-900nm through SEM characterization, and the silicon-titanium ratio is 65 through XRF analysis.
COMPARATIVE EXAMPLE 2 (not in accordance with the invention)
The improved classical method for synthesizing nanometer TS-1 zeolite molecular sieve is disclosed in the references Zeolite, 1992, vol,12, 943-950. 58.0g of deionized water and 30.0g of tetraethoxysilane are sequentially added into a plastic beaker, and after being uniformly stirred, 42.0g of tetrapropyl-grade hydroxide is added under the stirring stateAmmonium to obtain a solution 1, and continuously stirring for 1h; 1.31g of tetrabutyl titanate was added dropwise to 13.1g of isopropyl alcohol to obtain a solution 2; dropwise adding the solution 2 into the solution 1 under stirring, continuously stirring for 15min, heating to 80 deg.C, removing alcohol for 3 hr to obtain a glue solution with initial composition of SiO 2 ：TiO 2 ：TPAOH：H 2 O =1:0.027:0.36:35 (molar ratio). And transferring the obtained glue solution to a hydrothermal synthesis kettle, and statically crystallizing for 24 hours at 170 ℃. Filtering and washing the crystallized mother liquor, drying at 110 deg.C for 12h, and calcining at 500 deg.C for 3h to obtain nanometer TS-1 zeolite molecular sieve product, labeled as # 8. XRD test analysis shows that the crystalline phase is MFI topological structure; the grain size is 200-300nm through SEM test, and the silicon-titanium ratio is 37 through XRF analysis.
EXAMPLE 8 Cyclohexanone Ammoximation
Cyclohexanone ammoximation reaction with cyclohexanone, 25wt% 3 ·H 2 O、30wt％H 2 O 2 As raw materials, tert-butyl alcohol and water are used as solvents. The specific experimental steps are as follows: adding 2.0g of catalyst, 50ml of tert-butyl alcohol and 20ml of water into a reactor, heating to a set temperature of 75 ℃, and continuously introducing ammonia gas, hydrogen peroxide, cyclohexanone, tert-butyl alcohol and water for reaction, wherein the space velocity of the cyclohexanone is 12h -1 Reaction pressure normal pressure, ammonia: hydrogen peroxide: cyclohexanone =2.1:1.2:1 (mol/mol), cyclohexanone: tert-butyl alcohol: water =2.5:6.5:1 (g/g). The reaction time was 10h, and the liquid product was cooled in an ice-cold water bath and analyzed by gas chromatography.
Cyclohexanone conversion X% = (moles of cyclohexanone in the initial reaction-moles of cyclohexanone in the product)/(moles of cyclohexanone in the initial reaction) X100%
Cyclohexanone oxime selectivity S% = (moles cyclohexanone oxime in the product)/(moles cyclohexanone oxime in the initial reaction-moles cyclohexanone in the product) x 100%
The results of the cyclohexanone ammoximation reaction catalyzed by the zeolite molecular sieve are shown in table 1, the nano Ti-MFI/MOR eutectic molecular sieve has small grain size and a unique pore channel structure generated by structure distortion, and shows excellent catalytic performance in catalyzing cyclohexanone ammoximation to prepare cyclohexanone oxime.
TABLE 1 results of experiments on cyclohexanone ammoximation catalyzed by different zeolite molecular sieves
| Catalyst and process for producing the same | Cyclohexanone conversion X% | Cyclohexanone oxime selectivity S% |
| 1# | 99.7 | 99.9 |
| 2# | 99.9 | 99.9 |
| 3# | 99.1 | 99.9 |
| 4# | 98.8 | 99.9 |
| 5# | 98.6 | 99.9 |
| 6# | 99.9 | 99.9 |
| 7# | 82.8 | 98.6 |
| 8# | 97.9 | 99.7 |
Example 9 phenol hydroxylation reaction
The phenol hydroxylation reaction steps are as follows: putting the titanium silicalite molecular sieve, phenol, acetone and hydrogen peroxide into an intermittent reaction kettle, heating to 80 ℃ and reacting for 2 hours. Wherein in the reaction raw materials, the mass fraction of the zeolite molecular sieve is 5%, and the ratio of phenol/hydrogen peroxide is =4 (mol/mol), the ratio of acetone/phenol is =3 (mol/mol). The material after the centrifugal reaction was cooled and its product composition was analyzed by liquid chromatography.
Phenol conversion X% = (moles of phenol in the initial reaction-moles of phenol in the product)/(moles of phenol in the initial reaction) X100%
Dihydroxybenzene selectivity S% = (mole number of hydroquinone + catechol in product)/(mole number of phenol at the beginning of reaction-mole number of phenol in product) x 100%
The result of the phenol hydroxylation reaction catalyzed by the zeolite molecular sieve is shown in the table, the grain size of the nano Ti-MFI/MOR eutectic molecular sieve is small, the nano Ti-MFI/MOR eutectic molecular sieve has a unique pore channel structure generated by structural distortion, and the nano Ti-MFI/MOR eutectic molecular sieve has excellent catalytic performance in the reaction of preparing the benzenediol by phenol hydroxylation.
TABLE 2 Experimental results of phenol hydroxylation catalyzed by different zeolite molecular sieves
| Catalyst and process for preparing same | Phenol conversion X% | Selectivity of benzenediol S% |
| 1# | 21.3 | 95.2 |
| 2# | 22.1 | 95.1 |
| 3# | 21.7 | 95.5 |
| 4# | 21.1 | 96.2 |
| 5# | 21.6 | 95.7 |
| 6# | 22.2 | 96.3 |
| 7# | 13.8 | 86.5 |
| 8# | 19.3 | 95.3 |
Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.
Claims (7)
1. The application of the nano Ti-MFI/MOR eutectic molecular sieve in catalyzing cyclohexanone ammoxidation to prepare cyclohexanone oxime and phenol hydroxylation to prepare benzenediol is characterized in that: the method for synthesizing the nano Ti-MFI/MOR eutectic molecular sieve comprises the following steps: carrying out acid washing, water washing, drying and roasting on the nano MFI/MOR eutectic molecular sieve to obtain a dealuminated nano MFI/MOR eutectic molecular sieve; carrying out gas-solid phase isomorphous substitution on the dealuminated nano MFI/MOR eutectic molecular sieve and titanium tetrachloride to obtain a nano Ti-MFI/MOR eutectic molecular sieve, which is applied to preparing cyclohexanone oxime and phenol hydroxylation and preparing benzenediol by catalyzing cyclohexanone ammoxidation;
the method for synthesizing the nano MFI/MOR eutectic molecular sieve comprises the following steps:
(1) Mixing a silicon source, a template agent R and water, stirring at normal temperature and aging to obtain a mixture 1; carrying out hydrothermal crystallization on the mixture 1 at 130-180 ℃ for 6-168 h to obtain zeolite seed crystals;
(2) Mixing a silicon source, an aluminum source, an alkali source and water to form sol, adding zeolite seed crystal into the sol, wherein the zeolite seed crystal and the silicon source are both SiO 2 Counting, wherein the mass of the added zeolite seed crystal is 1-80 wt% of the mass of the added silicon source, and stirring and aging at normal temperature to obtain a mixture 2; performing hydrothermal crystallization on the mixture 2 at 130-200 ℃ for 6-168 hours, and performing solid-liquid separation, washing, drying and roasting on crystallized mother liquor to obtain a nano MFI/MOR eutectic molecular sieve;
the molar ratio of the materials in the mixture 1 in the step (1) is as follows: R/SiO 2 ＝0.01 ~ 1.0，H 2 O/SiO 2 10-100; the material molar ratio in the sol in the step (2) is as follows: siO 2 2 /Al 2 O 3 ＝6 ~ 100，M 2 O/SiO 2 = 0.15-2.0, M is alkali metal in alkali source, H 2 O/SiO 2 ＝10 ~ 100。
2. The application of the nano Ti-MFI/MOR eutectic molecular sieve in catalyzing the ammoxidation of cyclohexanone to prepare cyclohexanone oxime and the hydroxylation of phenol to prepare benzenediol according to claim 1, wherein: in the step (2), the adding mass of the zeolite seed crystal is 1-60 wt% of the adding mass of the silicon source.
3. The application of the nano Ti-MFI/MOR eutectic molecular sieve in catalyzing the ammoxidation of cyclohexanone to prepare cyclohexanone oxime and the hydroxylation of phenol to prepare benzenediol according to claim 1, wherein: in the step (1), the silicon source is an inorganic silicon source and/or an organic silicon source; the template agent R is one or more of n-butylamine, ethanolamine, diethanolamine, triethanolamine, ethylenediamine, hexamethylenediamine, diethylamine, tetrapropylammonium bromide and tetrapropylammonium hydroxide.
4. The application of the nano Ti-MFI/MOR eutectic molecular sieve in catalyzing cyclohexanone ammoxidation to prepare cyclohexanone oxime and phenol hydroxylation to prepare benzenediol according to claim 1, wherein the nano Ti-MFI/MOR eutectic molecular sieve is characterized in that: in the step (2), the silicon source is one or more of water glass, silica sol, white carbon black, tetraethoxysilane and methyl orthosilicate; the alkali source is one or more of sodium hydroxide and potassium hydroxide, and the aluminum source is one or more of aluminum sulfate, sodium aluminate, aluminum nitrate and aluminum isopropoxide.
5. The application of the nano Ti-MFI/MOR eutectic molecular sieve in catalyzing the ammoxidation of cyclohexanone to prepare cyclohexanone oxime and the hydroxylation of phenol to prepare benzenediol according to claim 1, wherein: and (3) stirring and aging at normal temperature for 1-24 h in the step (2).
6. The application of the nano Ti-MFI/MOR eutectic molecular sieve in catalyzing the ammoxidation of cyclohexanone to prepare cyclohexanone oxime and the hydroxylation of phenol to prepare benzenediol according to claim 1, wherein: the molar ratio of silicon-aluminum oxide to aluminum-silicon oxide of the dealuminized nano MFI/MOR eutectic molecular sieve SiO 2 /Al 2 O 3 ≥150。
7. The application of the nano Ti-MFI/MOR eutectic molecular sieve in catalyzing the ammoxidation of cyclohexanone to prepare cyclohexanone oxime and the hydroxylation of phenol to prepare benzenediol according to claim 1, wherein: the reaction temperature of gas-solid phase isomorphous substitution is 300-600 ℃, and the isomorphous substitution reaction time is 2-24 h.
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