CN117486230A - Crystallized pillared two-dimensional MFI molecular sieve and preparation method and application thereof - Google Patents
Crystallized pillared two-dimensional MFI molecular sieve and preparation method and application thereof Download PDFInfo
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- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 title claims abstract description 261
- 239000002808 molecular sieve Substances 0.000 title claims abstract description 259
- 238000002360 preparation method Methods 0.000 title claims abstract description 15
- DKGAVHZHDRPRBM-UHFFFAOYSA-N Tert-Butanol Chemical compound CC(C)(C)O DKGAVHZHDRPRBM-UHFFFAOYSA-N 0.000 claims abstract description 56
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 claims abstract description 49
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 47
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 46
- 238000002425 crystallisation Methods 0.000 claims abstract description 40
- 230000008025 crystallization Effects 0.000 claims abstract description 40
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 40
- 239000010703 silicon Substances 0.000 claims abstract description 40
- 238000005804 alkylation reaction Methods 0.000 claims abstract description 35
- 239000012808 vapor phase Substances 0.000 claims abstract description 15
- 238000000034 method Methods 0.000 claims description 36
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 30
- 238000006243 chemical reaction Methods 0.000 claims description 25
- 238000001354 calcination Methods 0.000 claims description 10
- 239000012071 phase Substances 0.000 claims description 7
- 239000007864 aqueous solution Substances 0.000 claims description 5
- 230000029936 alkylation Effects 0.000 claims description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-O ammonium group Chemical group [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims description 4
- 238000005342 ion exchange Methods 0.000 claims description 4
- 239000003054 catalyst Substances 0.000 abstract description 16
- 230000003197 catalytic effect Effects 0.000 abstract description 13
- 230000004048 modification Effects 0.000 abstract description 5
- 238000012986 modification Methods 0.000 abstract description 5
- 230000008929 regeneration Effects 0.000 abstract description 3
- 238000011069 regeneration method Methods 0.000 abstract description 3
- 230000002035 prolonged effect Effects 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 53
- 239000002253 acid Substances 0.000 description 38
- 239000000243 solution Substances 0.000 description 30
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 description 28
- 239000004094 surface-active agent Substances 0.000 description 26
- 239000000523 sample Substances 0.000 description 21
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 20
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 20
- 239000011148 porous material Substances 0.000 description 19
- 230000008569 process Effects 0.000 description 14
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 description 14
- 239000000376 reactant Substances 0.000 description 12
- 238000009826 distribution Methods 0.000 description 11
- UWKQJZCTQGMHKD-UHFFFAOYSA-N 2,6-di-tert-butylpyridine Chemical compound CC(C)(C)C1=CC=CC(C(C)(C)C)=N1 UWKQJZCTQGMHKD-UHFFFAOYSA-N 0.000 description 10
- QHPQWRBYOIRBIT-UHFFFAOYSA-N 4-tert-butylphenol Chemical compound CC(C)(C)C1=CC=C(O)C=C1 QHPQWRBYOIRBIT-UHFFFAOYSA-N 0.000 description 10
- 240000007839 Kleinhovia hospita Species 0.000 description 10
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 10
- 229910052782 aluminium Inorganic materials 0.000 description 10
- 238000006555 catalytic reaction Methods 0.000 description 10
- 238000010586 diagram Methods 0.000 description 10
- 229910052757 nitrogen Inorganic materials 0.000 description 10
- 239000002841 Lewis acid Substances 0.000 description 9
- 150000007517 lewis acids Chemical class 0.000 description 9
- 239000012295 chemical reaction liquid Substances 0.000 description 8
- 238000002329 infrared spectrum Methods 0.000 description 8
- 238000002156 mixing Methods 0.000 description 8
- 238000010521 absorption reaction Methods 0.000 description 7
- 239000004810 polytetrafluoroethylene Substances 0.000 description 7
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- 230000001588 bifunctional effect Effects 0.000 description 6
- 238000009792 diffusion process Methods 0.000 description 6
- 239000000693 micelle Substances 0.000 description 6
- 239000000377 silicon dioxide Substances 0.000 description 6
- 238000001179 sorption measurement Methods 0.000 description 6
- 238000002336 sorption--desorption measurement Methods 0.000 description 6
- 229940073455 tetraethylammonium hydroxide Drugs 0.000 description 6
- LRGJRHZIDJQFCL-UHFFFAOYSA-M tetraethylazanium;hydroxide Chemical compound [OH-].CC[N+](CC)(CC)CC LRGJRHZIDJQFCL-UHFFFAOYSA-M 0.000 description 6
- 230000008016 vaporization Effects 0.000 description 6
- 238000002441 X-ray diffraction Methods 0.000 description 5
- 230000032683 aging Effects 0.000 description 5
- 230000002209 hydrophobic effect Effects 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- JGDITNMASUZKPW-UHFFFAOYSA-K aluminium trichloride hexahydrate Chemical compound O.O.O.O.O.O.Cl[Al](Cl)Cl JGDITNMASUZKPW-UHFFFAOYSA-K 0.000 description 4
- 229940009861 aluminum chloride hexahydrate Drugs 0.000 description 4
- 229910021486 amorphous silicon dioxide Inorganic materials 0.000 description 4
- 238000003795 desorption Methods 0.000 description 4
- 239000007788 liquid Chemical class 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000001228 spectrum Methods 0.000 description 4
- 229910002808 Si–O–Si Inorganic materials 0.000 description 3
- 125000003277 amino group Chemical group 0.000 description 3
- 239000012298 atmosphere Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000007062 hydrolysis Effects 0.000 description 3
- 238000006460 hydrolysis reaction Methods 0.000 description 3
- 235000019353 potassium silicate Nutrition 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- 229910003849 O-Si Inorganic materials 0.000 description 2
- 229910003872 O—Si Inorganic materials 0.000 description 2
- 229910008051 Si-OH Inorganic materials 0.000 description 2
- 229910002800 Si–O–Al Inorganic materials 0.000 description 2
- 229910006358 Si—OH Inorganic materials 0.000 description 2
- 238000003917 TEM image Methods 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000002950 deficient Effects 0.000 description 2
- PPQREHKVAOVYBT-UHFFFAOYSA-H dialuminum;tricarbonate Chemical compound [Al+3].[Al+3].[O-]C([O-])=O.[O-]C([O-])=O.[O-]C([O-])=O PPQREHKVAOVYBT-UHFFFAOYSA-H 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 239000002135 nanosheet Substances 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- 238000002383 small-angle X-ray diffraction data Methods 0.000 description 2
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical compound [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 2
- 229910001948 sodium oxide Inorganic materials 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- LPSKDVINWQNWFE-UHFFFAOYSA-M tetrapropylazanium;hydroxide Chemical compound [OH-].CCC[N+](CCC)(CCC)CCC LPSKDVINWQNWFE-UHFFFAOYSA-M 0.000 description 2
- WJQOZHYUIDYNHM-UHFFFAOYSA-N 2-tert-Butylphenol Chemical compound CC(C)(C)C1=CC=CC=C1O WJQOZHYUIDYNHM-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 1
- 238000003547 Friedel-Crafts alkylation reaction Methods 0.000 description 1
- 238000007171 acid catalysis Methods 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- 229940118662 aluminum carbonate Drugs 0.000 description 1
- ZJOKNSFTHAWVKK-UHFFFAOYSA-K aluminum octadecanoate sulfate Chemical compound C(CCCCCCCCCCCCCCCCC)(=O)[O-].[Al+3].S(=O)(=O)([O-])[O-] ZJOKNSFTHAWVKK-UHFFFAOYSA-K 0.000 description 1
- -1 ammonium ions Chemical class 0.000 description 1
- 235000013405 beer Nutrition 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- SNRUBQQJIBEYMU-UHFFFAOYSA-N dodecane Chemical compound CCCCCCCCCCCC SNRUBQQJIBEYMU-UHFFFAOYSA-N 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- JEGUKCSWCFPDGT-UHFFFAOYSA-N h2o hydrate Chemical compound O.O JEGUKCSWCFPDGT-UHFFFAOYSA-N 0.000 description 1
- 239000002149 hierarchical pore Substances 0.000 description 1
- 238000003837 high-temperature calcination Methods 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000010808 liquid waste Substances 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 229940094933 n-dodecane Drugs 0.000 description 1
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000011973 solid acid Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
- C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
- C01B39/026—After-treatment
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
- B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
- C07C37/11—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by reactions increasing the number of carbon atoms
- C07C37/16—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by reactions increasing the number of carbon atoms by condensation involving hydroxy groups of phenols or alcohols or the ether or mineral ester group derived therefrom
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- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
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- C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
- C01P2002/82—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by IR- or Raman-data
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- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/04—Particle morphology depicted by an image obtained by TEM, STEM, STM or AFM
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- C01P2004/60—Particles characterised by their size
- C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention discloses a crystallized pillared two-dimensional MFI molecular sieve, a preparation method and application thereof, and in particular relates to the technical field of molecular sieve modification. According to the preparation method of the crystallized columnar two-dimensional MFI molecular sieve, firstly, a silicon source is introduced between adjacent layers of the columnar two-dimensional MFI molecular sieve sheet layer for vapor phase pillaring, then a structure guiding agent is introduced for secondary crystallization, and crystallized columnar is formed between the adjacent layers of the two-dimensional MFI molecular sieve, so that not only is the structural stability of the two-dimensional sheet layer MFI molecular sieve improved, but also the catalytic performance of the MFI molecular sieve in alkylation reaction of phenol and tertiary butanol is improved, the service life of the catalyst is prolonged, and the regeneration performance is excellent.
Description
Technical Field
The invention relates to the technical field of molecular sieve modification, in particular to a crystallized pillared two-dimensional MFI molecular sieve, and a preparation method and application thereof.
Background
Para-tertiary butyl phenol is one of the most industrially important alkylphenols, consisting of phenol and tertiary butyl phenolButanol is prepared by Friedel-Crafts alkylation. For the alkylation of phenol with tert-butanol to produce p-tert-butylphenol, liquid acids such as HF, H are generally employed industrially 2 SO 4 The catalyst is used as a series of problems such as large waste acid emission, serious equipment corrosion, high subsequent separation energy consumption and the like, and the adoption of a solid acid catalysis process mainly comprising an MFI molecular sieve can not only overcome the environmental safety problem, but also can regenerate the catalyst, thereby meeting the important requirements of national green low-carbon and clean production.
The MFI molecular sieve is a ten-membered ring cross pore structureHas the advantages of adjustable acidity and high thermal stability, and is suitable for catalyzing the alkylation reaction of phenol and tertiary butanol. However, the conventional microporous MFI molecular sieve has diffusion limitation in alkylation reaction of phenol and tertiary butanol due to a single microporous structure, so that the catalytic reaction activity is low and carbon deposition is easy to deactivate. Therefore, the two-dimensional MFI molecular sieve with the two-dimensional ultrathin lamellar structure is constructed, so that the diffusion path of guest molecules can be effectively shortened, more contactable active sites can be exposed, the mass transfer resistance of the MFI molecular sieve catalyst is reduced, the catalytic activity is improved, and the service life is prolonged. However, in the process of calcining and removing the organic template agent, the ordered structure of the multi-layer stack of the two-dimensional nano sheets of the traditional two-dimensional MFI molecular sieve is collapsed and is irregularly stacked, so that the mesoporous between the adjacent nano sheets of the two-dimensional MFI molecular sieve is lost, and a rapid diffusion channel cannot be provided for alkylation reaction of phenol and tertiary butanol. The problem can be solved by constructing a column support between adjacent layers of the two-dimensional MFI molecular sieve. The method of introducing the column support into the MFI molecular sieve sheet can be classified into a conventional column support and a vapor phase column support, the former adopts a solid-liquid mixing method, the method uses excessive solvent, and the synthesis and separation steps are complicated. The vapor phase column support directly adopts a vapor mode under the condition of solid-liquid separation to enable solute molecules to effectively enter between adjacent layers of the two-dimensional MFI molecular sieve, and compared with the conventional column support method, the silicon source added in the process is reduced by 10 times, and the product does not need to be recovered and separatedIs separated and does not produce liquid waste.
The prior art discloses a method for introducing a column support in a two-dimensional molecular sieve through a vapor phase strategy, and the column support type molecular sieve of a two-dimensional nanometer lamellar is prepared by placing the molecular sieve in the vapor of tetraethoxysilane and water and introducing a silicon dioxide column support in the molecular sieve lamellar. However, the column prepared by the prior art is composed of amorphous silica and is very sensitive to water molecules generated in the alkylation reaction of phenol and tert-butanol, which reduces the structural stability of the molecular sieve.
Disclosure of Invention
In order to solve the problem that amorphous silica pillared in a pillared two-dimensional MFI molecular sieve prepared by the prior art is unstable when meeting water, the invention provides a preparation method of a crystallized pillared two-dimensional MFI molecular sieve, and a structure guiding agent is introduced after the silica pillared is constructed between molecular sieve sheets by a vapor phase pillared method, so that crystallized silica pillared is formed between each sheet in the molecular sieve structure, and the collapse of the structure of the molecular sieve, which is easy to happen after meeting water, is inhibited.
Another object of the present invention is to provide a crystallized pillared two-dimensional MFI molecular sieve.
The invention also aims to provide an application of the crystallized pillared two-dimensional MFI molecular sieve in catalyzing alkylation reaction of phenol and tertiary butanol.
The above object of the present invention is achieved by the following technical scheme:
the preparation method of the crystallized pillared two-dimensional MFI molecular sieve comprises the following steps:
s1, placing a two-dimensional lamellar MFI molecular sieve which is not subjected to column support in silicon source steam for steam phase column support, and obtaining a steam phase column support type two-dimensional MFI molecular sieve after column support reaction is completed;
s2, sequentially placing the vapor-phase pillared two-dimensional MFI molecular sieve obtained in the step S1 into structure directing agent vapor and water vapor for crystallization, and obtaining the crystallized pillared two-dimensional MFI molecular sieve after crystallization is completed.
Both silicon sources and structure directing agents conventional in the art may be used in the present invention. Specifically, the silicon source in step S1 of the present invention may be ethyl orthosilicate; the structure directing agent in step S2 may be tetrapropylammonium hydroxide.
Step S1 is in fact a one-step conventional process for preparing a silica vapor phase pillared two-dimensional MFI molecular sieve. In the steps S1 and S2, the two-dimensional lamellar MFI molecular sieve which is not subjected to column support is sequentially placed in silicon source steam, structure guiding agent steam and water steam, silicon atoms can be introduced into adjacent molecular sieve lamellar in the two-dimensional lamellar MFI molecular sieve, and then the structure guiding agent is introduced between the adjacent lamellar, so that the silicon atoms can be orderly arranged; and finally, placing the vapor phase pillared molecular sieve in water vapor for hydrolysis and crystallization, wherein silicon atoms in ordered arrangement can be converted into crystallized MFI molecular sieve pillared, so that the MFI molecular sieve has excellent stability.
In the specific embodiment of the invention, the silicon source steam in the step S1 is obtained by vaporizing a silicon source solution at 100-200 ℃; the structure directing agent steam in the step S2 is obtained by vaporizing the structure directing agent solution at 100-200 ℃, and the water steam is obtained by vaporizing the water at 60-100 ℃. The vaporization temperatures of the structure directing agent solution and water in step S2 are respectively the crystallization temperatures of the vapor phase pillared two-dimensional MFI molecular sieve when crystallization is performed in the structure directing agent vapor and the water vapor. This is because, in the embodiment of the present invention, the specific operation for crystallizing the molecular sieve is: the method comprises the steps of filling a vapor phase column support type two-dimensional MFI molecular sieve into a small PTFE bottle, sequentially placing the small PTFE bottle into another large PTFE bottle which is respectively filled with a structure directing agent solution and water, placing the small PTFE bottle in the large PTFE bottle in an open mode, then placing the small PTFE bottle in a hydrothermal reaction kettle, finally placing the small PTFE bottle in an oven, adjusting the temperature of the oven to a crystallization temperature, at the moment, respectively vaporizing the structure directing agent solution and water to form structure directing agent vapor and water vapor, and sequentially entering the structure directing agent molecules and water molecules into a sheet layer of the two-dimensional MFI molecular sieve for crystallization.
Preferably, the molar ratio of the structure directing agent in step S2 to the silicon source in step S1 is 1 (1.5-2).
In a specific embodiment of the present invention, the silicon source vapor in step S1 and the structure directing agent vapor in step S2 are obtained by vaporizing an aqueous silicon source solution and an aqueous structure directing agent solution, respectively, so that the molar ratio of the structure directing agent to the silicon source refers to the molar ratio of the silicon source and the structure directing agent in the aqueous silicon source solution.
The molar ratio of the control structure directing agent to the silicon source is 1: (1.5-2) the amorphous silica column introduced between the two-dimensional MFI molecular sieve sheets can be fully crystallized, and the obtained molecular sieve has more micropore structure and higherThe acid site concentration can exhibit higher catalytic activity in catalyzing the alkylation reaction of phenol with t-butanol. When the amount of the structure directing agent added is too small, the amorphous silica column is difficult to crystallize sufficiently; when the structure directing agent is too much, the silicon atoms introduced between the two-dimensional MFI molecular sieve sheets need to be crystallized around the periphery of the structure directing agent, and the too much structure directing agent can be mutually aggregated, so that the silicon atoms at the periphery of the structure directing agent cannot be closely arranged, the original amorphous silicon dioxide column is difficult to crystallize, and the number of micropores of the obtained molecular sieve is equal to that of the amorphous silicon dioxide column>The acid site concentration is also difficult to increase.
Preferably, the crystallization temperature in step S2 is 60-200deg.C.
Preferably, the total time of crystallization in step S2 is 36-60 hours.
When the crystallization temperature and the total crystallization time in the step S2 are controlled to be respectively in the ranges, the crystallization process which occurs in the two-dimensional MFI molecular sieve sheet layer can be fully performed, and the reaction energy consumption is suitable.
Preferably, after the crystallization in the step S2 is completed, the crystallized pillared two-dimensional MFI molecular sieve is calcined, and after the calcination is completed, the crystallized pillared two-dimensional MFI molecular sieve is placed in an aqueous solution containing ammonium groups for ion exchange.
In the concrete of the inventionIn embodiments, the specific conditions for calcination may be N at 400-500 DEG C 2 Calcining for 6-8 h in the atmosphere, and calcining for 10-12 h in the air atmosphere at 550-600 ℃; the aqueous solution containing ammonium groups may be NH 4 Aqueous Cl solution.
Calcining the obtained molecular sieve after crystallization is completed to remove the residual structure directing agent; after the calcination is finished, the molecular sieve is placed in an aqueous solution containing ammonium to carry out ion exchange, so that the property of the surface of the molecular sieve can be changed by utilizing ammonium ions, and the catalytic performance of the obtained crystallized pillared two-dimensional MFI molecular sieve is further improved.
Preferably, the mass ratio of the two-dimensional lamellar MFI molecular sieve without column support to the silicon source in the step S1 is 1 (0.05-3.75).
The mass ratio of the two-dimensional lamellar MFI molecular sieve to the silicon source is controlled to be 1 (0.05-3.75), so that the quantity of silicon atoms introduced into the molecular sieve lamellar is proper, and further, amorphous silicon dioxide pillars which can be formed by the silicon atoms and crystallized silicon dioxide pillars which are formed by subsequent transformation are both proper in density. The silicon source is too little, the crystallized silicon dioxide column support formed in the molecular sieve is little, and the stability of the molecular sieve in the catalysis process is improved to a small extent; the silicon source is too much, the column support formed in the molecular sieve is too much and coarse, and when the obtained molecular sieve is adopted to catalyze the reaction, the diffusion of reactants in the molecular sieve is difficult to carry out, and the reaction efficiency is low.
Preferably, the two-dimensional lamellar MFI molecular sieve without column support in step S1 is prepared by the following preparation method:
mixing a bifunctional surfactant, a silicon source and water to obtain a solution A, mixing the solution A with an aluminum source and strong protonic acid to obtain a solution B, aging the solution B to obtain gel C, and crystallizing to obtain a two-dimensional lamellar MFI molecular sieve without column support;
the difunctional surfactant is a Bola type surfactant, and the hydrophilic group of the surfactant is an amino group.
In the specific embodiment of the invention, the molar ratio of the silicon source to the aluminum source to the difunctional surfactant to the strong protonic acid to the water is 1 (0.01-0.04): (0.02-0.08): (0.16-0.2): (50-80); the specific silicon source can be water glass, the aluminum source can be selected from one or more of aluminum chloride hexahydrate, aluminum sulfate octadecanoate and aluminum carbonate, the strong protonic acid can be sulfuric acid, the aging condition can be that the silicon source is placed at 50-75 ℃ for 4-8 h, and the crystallization condition can be that the silicon source is reacted at 100-150 ℃ for 24h.
The two-dimensional lamellar MFI molecular sieve prepared by the method is subjected to crystallization column support modification, and the obtained molecular sieve has better catalytic performance, because the molecular sieve prepared by the method has a more complete and regular lamellar structure. The Bola type surfactant is a compound formed by connecting and bonding two hydrophilic polar groups and one or two hydrophobic chains, has a structure of hydrophilic at two ends and hydrophobic at the middle part, can form a micelle structure matched with an MFI molecular sieve structure, namely can be used as a template agent in the process of synthesizing the MFI molecular sieve; the Bola type surfactant adopted by the invention contains amino and N + Can be used as a structure directing agent to induce the synthesis of the MFI molecular sieve. Thus, bola type surfactants are referred to herein as dual function surfactants. In a specific embodiment of the present invention, the amine group-containing Bola type surfactant may be C ph-10-6-6 、C 22-6-6 And BC (binary code) ph-12-6-6 Br 4 Any one or more of wherein C ph-10-6-6 The molecular structure of (C) 6 H 5 -O-(CH 2 ) 10 -N + (CH 3 ) 2 -C 6 H 12 -N + (CH 3 ) 2 -C 6 H 13 ]·2[Br - ]；C 22-6-6 The molecular structure of (C) 22 H 45 -N + (CH 3 ) 2 -C 6 H 12 -N + (CH 3 ) 2 -C 6 H 13 ]·2[Br - ]；BC ph-12-6-6 Br 4 The molecular structure of (2) is: [ C 6 H 13 -N + (CH 3 ) 2 -C 6 H 12 -N + (CH 3 ) 2 -(CH 2 ) 12 -O-(p-C 6 H 4 ) 2 -O-(CH 2 ) 12 -N + (CH 3 ) 2 -C 6 H 12 -N + (CH 3 ) 2 -C 6 H 13 ]·4[Br - ]。
After mixing the Bola type surfactant with a silicon source and an aluminum source, the Bola type surfactant can serve as a template agent for guiding the silicon source and the aluminum source to generate an MFI molecular sieve structure by forming a micelle (silicon atoms and aluminum atoms are orderly arranged on the outer surface of the micelle), and meanwhile N in the amine group of the surfactant + The group can be used as a structure guiding agent for inducing the generation of the MFI molecular sieve, and the hydrophobic long chain in the middle of the Bola type surfactant can prevent the growth of the MFI molecular sieve in the b-axis direction through the hydrophobic effect, so that the MFI molecular sieve can form a two-dimensional structure. In addition, the hydrophobic long chain in the middle of the Bola type surfactant ensures that the formed micelle structure is of a mesoporous scale, further ensures that the obtained two-dimensional MFI molecular sieve has a mesoporous structure, and can enable reactants to quickly pass through without blocking when catalyzing alkylation reaction of phenol and tertiary butanol. The purpose of adding strong protonic acid in the steps is to adjust the pH value of a reaction system, so that an aluminum source and a silicon source can form a framework of the MFI molecular sieve around stable micelles formed by the surfactant under a proper environment. After constructing an MFI molecular sieve framework (obtaining liquid B), aging and crystallizing are carried out, so that the conventional two-dimensional flaky MFI molecular sieve can be prepared.
When the mole ratio of the silicon source to the aluminum source to the bifunctional surfactant to the protonic acid to the water in the step S1 is 100 (1-4) (2-8) (16-20) (5000-8000), the MFI molecular sieve can be formed after the process of the step S1-S3. When the addition amount of the silicon source or the aluminum source is too large or too small, the needed MFI molecular sieve structure cannot be synthesized, or the synthesized molecular sieve does not have a two-dimensional morphology; the difunctional surfactant simultaneously plays a role of a template agent and a structure guiding agent, so that when the dosage of the difunctional surfactant is too small, the needed MFI molecular sieve can not be synthesized, and when the dosage of the difunctional surfactant is too large, the template in the system is too large, so that the structure of the MFI molecular sieve is loose, and the molecular sieve is easy to decompose; the purpose of adding the protonic acid in the invention is to regulate the pH value of the system, the dosage of the protonic acid is too small, which can lead to insufficient acidity of the reaction system, and sol which is required to be formed when the molecular sieve is synthesized can not be formed, and when the dosage of the protonic acid is too large, the acidity of the system is too strong, and the sol can not be formed.
More preferably, the above-mentioned bifunctional surfactant is BC ph-12-6-6 Br 4 。
Using BC ph-12-6-6 Br 4 As a surfactant in the construction of unistrut two-dimensional lamellar MFI molecular sieves, the resulting molecular sieves have a more stable structure due to BC ph-12-6-6 Br 4 The phenyl ring of (2) can stabilize the micelle structure through strong pi-pi stacking interaction to form a stable cylindrical assembly unit matched with the MFI topological structure, namely, the phenyl ring is used as a stable template agent, so that the synthesized molecular sieve has a more regular structure, and can stably exist at a high temperature of more than 500 ℃.
The invention also protects the crystallized pillared two-dimensional MFI molecular sieve prepared by the preparation method of the crystallized pillared two-dimensional MFI molecular sieve.
The invention also protects application of the crystallized pillared two-dimensional MFI molecular sieve in catalyzing alkylation reaction of phenol and tertiary butanol.
Preferably, the mass airspeed of the phenol and the tertiary butanol is 2-10 h when the crystallization pillared two-dimensional MFI molecular sieve catalyzes alkylation reaction of the phenol and the tertiary butanol -1 。
Space velocity refers to the amount of feed per unit of time that passes through a unit of catalyst and reflects the throughput of the catalyst. In a specific embodiment of the present invention, the mass space velocity of the reaction solution at the time of introducing the reaction solution into the reactor is the mass flow rate of the raw material (unit is kg h -1 ) Ratio to catalyst mass (kg). Industrially, the mass space velocity of the reaction liquid which is introduced into the reactor when catalyzing the alkylation reaction between phenol and tertiary butanol is generally 0.5 to 2 hours -1 The crystallization pillared two-dimensional MFI molecular sieve catalyst provided by the invention has the advantage of high catalytic activity, and can enable alkylation reaction between phenol and tertiary butanol to be rapidly carried out, so that the mass airspeed of the reaction liquid when the reaction liquid is introduced into the reactor is 2-10 h -1 Catalytic reaction under severe conditions.
Preferably, the molar ratio of phenol to tertiary butanol is 1 (1-4) when the crystallized pillared two-dimensional MFI molecular sieve catalyzes alkylation reaction of phenol and tertiary butanol.
Preferably, the reaction temperature of the crystallized pillared two-dimensional MFI molecular sieve is 100-180 ℃ when catalyzing alkylation reaction of phenol and tertiary butanol.
Compared with the prior art, the invention has the beneficial effects that:
the crystallized pillared two-dimensional MFI molecular sieve prepared by the preparation method provided by the invention has crystallized silicon dioxide pillared which can still exist stably when meeting water, so that the collapse of the structure of the molecular sieve in the process of catalyzing alkylation reaction of phenol and tertiary butanol can be effectively prevented. The molecular sieve prepared by the invention catalyzes alkylation reaction of phenol and tertiary butanol, and the mass airspeed of the molecular sieve when reactants phenol and tertiary butanol are introduced into a system is 5h -1 Under the condition of the catalyst, the single-pass service life is as long as 29 hours, the conversion rate of phenol is 80-85%, and the selectivity of p-tert-butylphenol is 70-80%.
Drawings
FIG. 1 shows XRD patterns of crystallized pillared two-dimensional MFI molecular sieves obtained in examples 1 to 3 of the present invention.
FIG. 2 shows that the MFI molecular sieves obtained in examples 1 to 3 of the present invention were 1600 to 1400cm when pyridine and 2, 6-di-t-butylpyridine were used as probe molecules, respectively -1 Wherein (a) is an infrared spectrum obtained by using pyridine as a probe molecule, and (b) is an infrared spectrum obtained by using 2, 6-di-t-butylpyridine as a probe molecule.
Fig. 3 is a diagram showing the isothermal line of nitrogen adsorption-desorption and the pore size distribution diagram obtained by measuring the isothermal line of nitrogen adsorption-desorption of the crystallized pillared two-dimensional MFI molecular sieves obtained in examples 1 to 3 according to the present invention, wherein (a) is the isothermal line of nitrogen adsorption-desorption and (b) is the pore size distribution diagram.
FIG. 4 shows XRD patterns of MFI molecular sieves obtained in example 1 and comparative examples 1 to 4 of the present invention.
FIG. 5 shows the results of example 1 and comparative example of the present invention using pyridine and 2, 6-di-t-butylpyridine as probe molecules, respectivelyThe MFI molecular sieves obtained in examples 1 to 4 were in the range of 1600 to 1400cm -1 Wherein (a) is an infrared spectrum obtained by using pyridine as a probe molecule, and (b) is an infrared spectrum obtained by using 2, 6-di-t-butylpyridine as a probe molecule.
FIG. 6 is a graph showing the isothermal diagrams of nitrogen adsorption and desorption and pore size distribution of the two-dimensional MFI molecular sieves obtained in example 1 and comparative examples 1 to 4 according to the present invention, wherein (a) is the isothermal diagram of nitrogen adsorption and desorption and (b) is the pore size distribution.
FIG. 7 shows the MFI molecular sieves obtained in example 1 and comparative examples 1 to 4 of the present invention at 800 to 400cm -1 And 4000 to 1500cm -1 Wherein (a) is the MFI molecular sieve obtained in example 1 and comparative examples 1 to 4 in a range of 800 to 400cm -1 The MFI molecular sieves obtained in example 1 and comparative examples 1 to 4 were in the range of 4000 to 1500cm -1 Is a spectrum of infrared light of (a) is obtained.
Fig. 8 is a TEM image of a crystallized pillared two-dimensional MFI molecular sieve obtained in example 1 of the present invention.
FIG. 9 is a graph showing the comparison of the catalytic performance of the MFI molecular sieves obtained in example 1 and comparative examples 1 to 4 of the present invention in catalyzing the alkylation reaction of phenol with t-butanol, wherein (a) is a graph of the conversion of phenol and (b) is a graph of the selectivity to p-t-butylphenol.
FIG. 10 is a graph showing the comparison of the performance of the MFI molecular sieves obtained in example 1 and comparative example 3 of the present invention in catalyzing the alkylation of phenol with t-butanol after regeneration, wherein (a) is a graph of the conversion of phenol and (b) is a graph of the selectivity to p-t-butylphenol.
Detailed Description
The invention will be further described with reference to the following specific embodiments, but the examples are not intended to limit the invention in any way. Raw materials reagents used in the examples of the present invention are conventionally purchased raw materials reagents unless otherwise specified.
Example 1
The preparation method of the crystallized pillared two-dimensional MFI molecular sieve comprises the following steps:
s1, placing a two-dimensional lamellar MFI molecular sieve which is not subjected to column support in tetraethoxysilane steam at 150 ℃ for steam phase column support, and obtaining a steam phase column support type two-dimensional MFI molecular sieve after the column support reaction is completed;
s2, sequentially placing the vapor phase pillared two-dimensional MFI molecular sieve obtained in the step S1 into tetraethylammonium hydroxide (structure directing agent) steam at 150 ℃ and water steam at 80 ℃ for crystallization for 24 hours, namely, sequentially performing crystallization at 150 ℃ and 80 ℃ for 24 hours, wherein the total crystallization time is 48 hours; calcining to remove template agent, and adopting NH 4 Performing ion exchange on the Cl aqueous solution to obtain a crystallized pillared two-dimensional MFI molecular sieve;
the mass ratio of the two-dimensional lamellar MFI molecular sieve which is not subjected to column support to the silicon source in the step S1 is 1:0.5;
the molar ratio of the structure directing agent in step S2 to the silicon source in step S1 is 1:1.67;
the two-dimensional lamellar MFI molecular sieve which is not supported by the column and is adopted in the step S1 is prepared by adopting the following preparation method:
mixing a bifunctional surfactant, water glass and water to obtain a solution A, mixing the solution A with aluminum chloride hexahydrate and sulfuric acid to obtain a solution B, aging the solution B to obtain gel C, and crystallizing to obtain a two-dimensional lamellar MFI molecular sieve without column support;
the above bifunctional surfactant is Bola type surfactant, specifically BC ph-12-6-6 Br 4 The method comprises the steps of carrying out a first treatment on the surface of the Meanwhile, the molar ratio of the silicon source (water glass), the aluminum source (aluminum chloride hexahydrate), the bifunctional surfactant, the strong protonic acid (sulfuric acid) and water is 1:0.02:0.06:0.186:60.
Example 2
A process for preparing a crystallized pillared two-dimensional MFI molecular sieve, wherein the difference from example 1 is:
the molar ratio of the structure directing agent in step S2 to the silicon source in step S1 is 1:1.11.
Example 3
A process for preparing a crystallized pillared two-dimensional MFI molecular sieve, wherein the difference from example 1 is:
the molar ratio of the structure directing agent in step S2 to the silicon source in step S1 is 1:0.83.
Comparative example 1
A method for preparing a vapor phase pillared two-dimensional MFI molecular sieve, wherein the difference from example 1 is that:
only step S1 is performed.
Comparative example 2
A method for preparing a two-dimensional lamellar MFI molecular sieve without column support, wherein the difference from example 1 is that:
steps S1 to S2 are not performed.
Comparative example 3
A method for preparing a conventional pillared two-dimensional MFI molecular sieve, wherein the difference from example 1 is that:
s1, adding a two-dimensional lamellar MFI molecular sieve which is not subjected to pillaring into an tetraethoxysilane solution at room temperature to perform conventional pillaring, and reacting for 12 hours to obtain a precursor of the conventional pillared two-dimensional MFI molecular sieve;
s2, placing the precursor of the conventional pillared two-dimensional MFI molecular sieve obtained in the step S1 into water at 90 ℃ for 12h of crystallization, and calcining at 550 ℃ to remove the template agent to obtain the conventional pillared two-dimensional MFI molecular sieve.
Comparative example 4
A commercial MFI molecular sieve, specifically ZSM-5 molecular sieve NKF-5D-25HWGRYH, is available from Tianjin southbound catalyst Co.
The preparation of commercial ZSM-5 molecular sieves provided in comparative example 4 above is conventional in the art and differs from comparative example 2 at least in:
s1, mixing a structure directing agent TPAOH, tetraethoxysilane and water to obtain a solution A, mixing the solution A with aluminum chloride hexahydrate and sodium oxide to obtain a solution B, and aging the solution B to obtain gel C;
s2, crystallizing the gel C obtained in the step S1 to obtain a commercial MFI molecular sieve;
the molar ratio of the silicon source, the aluminum source, the structure directing agent, the sodium oxide and the water in the step S1 is 30:1:1:3.25:958.
performance testing
XRD test: MFI molecular sieves of different morphologies prepared in the examples and comparative examples were characterized using a D8 Advance type X-ray diffractometer from Bruker, germany.
Distribution of acid sites in the molecular sieve pore skeleton: pyridine and 2, 6-di-tert-butylpyridine are used as probe molecules, and two-dimensional MFI molecular sieves with different morphologies prepared in examples and comparative examples are subjected to data acquisition on a German Bruker Vertex 70 type Fourier transform infrared spectrometer, and calculated by beer's law>Acid and Lewis acid concentrations.
Specific surface area and pore size testing: ASAP 2460 multi-station full-automatic specific surface and aperture analyzer of McMemerdrel is adopted to collect data of two-dimensional MFI molecular sieves with different morphologies prepared in examples and comparative examples.
TEM test: the crystallized pillared two-dimensional MFI molecular sieve prepared in example 1 was characterized by using a FEI Talos 200S transmission electron microscope, and a transmission electron microscope image was obtained.
Catalytic performance test: the catalyst obtained in the examples and the comparative examples is granulated to obtain a catalyst sample, the catalyst sample is sieved by a 20-30 mesh sieve, about 1.0g of the sample is taken and put into an oven, and the catalyst sample is activated for 3 hours at 550 ℃ in an air atmosphere. Preparing a reaction solution from phenol and tertiary butanol according to a molar ratio of 1:2, adding a certain amount of n-dodecane as an internal standard, and regulating the flow rate of the reaction solution to a mass airspeed of 5h -1 Taking a certain reaction liquid as a sample after reacting for a certain time under normal pressure, measuring the content of tert-butylphenol in the reaction liquid, and calculating the selectivity of the catalyst to the target reaction and the conversion rate of the catalyst to the reactant phenol.
The performance test data are shown in tables 1 to 4 and figures 1 to 10 below:
table 1 acid site concentration of example and comparative molecular sieves
As can be seen from Table 1, the crystallized pillared two-dimensional MFI molecular sieves prepared in examples 1 to 3 of the present invention each have a Lewis acid site concentration lower than that of the two-dimensional MFI molecular sieve obtained in comparative example 2 without pillared, whileThe concentration of the acid sites is higher, which can prove that the method provided by the invention can be used for introducing the pillared between the sheets of the two-dimensional MFI molecular sieve, because the Lewis acid sites on the surface of the molecular sieve can react with the silicon hydroxyl groups on the surface of the molecular sieve in the pillared process to form Si-O-Si or Al-O-Si bonds, the defect sites on the surface of the molecular sieve are complete, and the Lewis acid sites are further converted into
Acid sites. The non-pillared MFI molecular sieve provided in comparative example 2 of the present invention is a two-dimensional structure although not pillared, whereas the commercial molecular sieve provided in comparative example 4 has an ideal three-dimensional structure, maintaining the integrity of the crystals (i.e., fewer defective sites), and thus ∈ ->The acid site concentration is higher.
Table 2 pore channel data for example and comparative molecular sieves
As can be seen from table 2 above, the crystallized pillared two-dimensional MFI molecular sieves prepared in examples 1 to 3 of the present invention have a higher specific surface area than the two-dimensional MFI molecular sieves obtained in comparative example 2, which also demonstrates that the method provided by the present invention can introduce the pillared between two-dimensional MFI molecular sieve sheets, because two adjacent two-dimensional MFI molecular sieve sheets form a new pore structure after the pillared is introduced, and the specific surface area can be increased; meanwhile, compared with the vapor phase pillared two-dimensional MFI molecular sieve obtained in comparative example 1, the crystallized pillared two-dimensional MFI molecular sieves provided in examples 1 to 3 of the present invention have higher micropore specific surface area and micropore volume, because the preparation method provided in the present invention can introduce crystallized pillared between two-dimensional MFI molecular sieve sheets, and the pillared forms a micropore structure during crystallization, so that micropore channels are increased, and micropore specific surface area and micropore volume are both improved.
As can be seen from comparing the data of examples 1 to 3 in tables 1 to 2, when the molar ratio of tetraethylammonium hydroxide in the tetraethylammonium hydroxide solution in step S3 to tetraethyl orthosilicate in the tetraethyl orthosilicate solution in step S2 is within the range of 1 (1.5 to 2) which is preferred in the present invention (example 1), the resulting molecular sieve has more microporous structure and higherAcid site concentration. When the molar ratio of tetraethylammonium hydroxide to tetraethyl orthosilicate as structure directing agent is lower (examples 2-3), the number of micropores and +.>The concentration of acid sites is reduced; and when this molar ratio is higher, the number of micropores and +.>The concentration of acid sites is difficult to rise again.
Table 3 conversion of phenol by the example and comparative molecular sieves
Table 4 p-tert-butylphenol selectivity for example and comparative molecular sieves
Note that: the data for examples 2-3 in tables 3-4 above are similar to, but slightly lower than, example 1.
As can be seen from tables 3 to 4 above, the crystallization pillared two-dimensional MFI molecular sieves provided by the examples of the present invention are used for catalyzing alkylation reaction of phenol and tert-butanol, and have the highest reactant (phenol) conversion rate and highest product (p-tert-butylphenol) selectivity in the whole process compared with the catalysis of various two-dimensional MFI molecular sieves provided by the comparative examples, because the crystallization pillared introduced between two-dimensional MFI molecular sieve sheets of the present invention can increase the pore channel number of micropores and increaseThe concentration of acid sites when molecular sieves are used to catalyze the reaction between organic substances>The acidic sites are active sites for catalytic reaction, so that the molecular sieve provided by the invention is used for catalyzing alkylation reaction between phenol and tertiary butanol, which is not only beneficial to effective contact (increase of active site number) of reactants and active sites, but also enhances internal diffusion (increase of micropore channels) of reactant molecules, thereby improving alkylation reaction activity. The molecular sieve provided in example 1 of the present invention still has excellent catalytic activity when the catalytic reaction has been carried out for 29 hours, which indicates that the crystallized pillared two-dimensional MFI molecular sieve provided in the present invention has excellent stability because water molecules are generated in the alkylation reaction of phenol and t-butanol, but the generation of water molecules does not lead to the hydrolysis of crystallized silica pillared in the molecular sieve. It is to be noted that the mass space velocity of the reactants when the reactants are introduced into the system for catalyzing the alkylation reaction of phenol and tertiary butanol by adopting the series of two-dimensional MFI molecular sieves provided by the invention is 5h -1 . Industrially, the mass space velocity of the reaction liquid which is introduced into the reactor when catalyzing the alkylation reaction between phenol and tertiary butanol is generally 0.5 to 2 hours -1 The crystallization pillared two-dimensional MFI molecular sieve catalyst provided by the invention hasHas the advantage of high catalytic activity, can lead the alkylation reaction between phenol and tertiary butanol to be rapidly carried out, thus the mass space velocity of the reaction liquid when the reaction liquid is fed into the reactor is 5h -1 Catalytic reaction under severe conditions.
The crystallized pillared two-dimensional MFI molecular sieves provided in examples 2-3 of the present invention have lower catalytic activity than the molecular sieves prepared in example 1 by controlling the molar ratio of tetraethylammonium hydroxide in the tetraethylammonium hydroxide solution in step S3 to tetraethyl orthosilicate in the tetraethyl orthosilicate solution in step S2 within the preferred range of 1 (1.5-2) of the present invention, because the molecular sieves obtained when the above molar ratio is not within the preferred range have lower micropore count and lower micropore countAcid site concentration.
FIG. 1 shows XRD patterns of crystallized pillared two-dimensional MFI molecular sieves obtained in examples 1 to 3 of the present invention. As can be seen from fig. 1, the two-dimensional MFI molecular sieves with crystal nucleus and pillared structure provided in examples 1 to 3 of the present invention all have diffraction peaks at 2θ of 7.9 °,8.8 °,23.2 °, and 23.8 °, which are characteristic peaks of XRD spectrum of MFI molecular sieve, which can prove that typical MFI molecular sieve is prepared in the present invention, and the MFI molecular sieve structure is preserved in the pillared process. Meanwhile, the X-ray diffraction peaks of the molecular sieves obtained in examples 1 to 3 of the present invention are all peaks, which indicate that the structure of the two-dimensional MFI molecular sieve after the introduction of the crystallization column support is still ordered.
FIG. 2 shows that the MFI molecular sieves obtained in examples 1 to 3 of the present invention were 1600 to 1400cm when pyridine and 2, 6-di-t-butylpyridine were used as probe molecules, respectively -1 Wherein (a) is an infrared spectrum obtained by using pyridine as a probe molecule, and (b) is an infrared spectrum obtained by using 2, 6-di-t-butylpyridine as a probe molecule. As can be seen by comparing FIGS. 2 (a) (b), the infrared absorption peak intensities in the infrared spectrogram of example 1 are higher when pyridine is used as the probe molecule, and the infrared absorption peak intensities of examples 2 to 3 are higher when 2, 6-di-t-butylpyridine having a larger molecular volume is used as the probe molecule, which indicates that the molecular sieve obtained in example 1 has poresThe concentration of acid sites was higher, whereas the molecular sieves of examples 2-3 had their surfacesThe concentration of acid sites is higher because pyridine is adsorbed in the microporous channels of the molecular sieve when pyridine with smaller molecular volume is used as a probe molecule>At the acid site.
Fig. 3 is a diagram showing the isothermal line of nitrogen adsorption-desorption and the pore size distribution diagram obtained by measuring the isothermal line of nitrogen adsorption-desorption of the crystallized pillared two-dimensional MFI molecular sieves obtained in examples 1 to 3 according to the present invention, wherein (a) is the isothermal line of nitrogen adsorption-desorption and (b) is the pore size distribution diagram. As can be seen from fig. 3, the molecular sieve provided in example 1 of the present invention has a higher number of micropores and a higher specific surface area.
FIG. 4 shows XRD patterns of MFI molecular sieves obtained in example 1 and comparative examples 1 to 4 of the present invention. As can be seen from fig. 4, the MFI molecular sieves obtained in example 1 and comparative examples 1 to 4 of the present invention all exhibited diffraction peaks at characteristic peaks corresponding to the MFI molecular sieves. Meanwhile, it can be seen from the small angle XRD patterns that the commercial molecular sieve provided in comparative example 4 was free of diffraction peaks, whereas the molecular sieves provided in other examples or comparative examples all showed diffraction peaks in the small angle XRD patterns, which indicates that the molecular sieves in other examples or comparative examples were ordered lamellar structures. In addition, the sharpness of diffraction peaks is gradually enhanced from the two-dimensional MFI molecular sieve which is not pillared (comparative example 2) to the conventional two-dimensional MFI molecular sieve which is pillared (comparative example 3) and the vapor phase two-dimensional MFI molecular sieve which is pillared (comparative example 1) to the crystallized two-dimensional MFI molecular sieve (example 1) in the XRD spectrum, which indicates that the molecular sieve provided by the invention has higher structural order.
FIG. 5 shows that the MFI molecular sieves obtained in example 1 and comparative examples 1 to 4 of the present invention were 1600 to 1400cm when pyridine and 2, 6-di-t-butylpyridine were used as probe molecules, respectively -1 Is characterized by that in the course of infrared spectrogram,wherein (a) is an infrared spectrum obtained by using pyridine as a probe molecule, and (b) is an infrared spectrum obtained by using 2, 6-di-tert-butylpyridine as a probe molecule. As can be seen from FIG. 5 (a), the MFI molecular sieves provided in the examples of the present invention and the comparative examples all exhibitCharacteristic absorption peaks at the acid site and Lewis acid site, at-1545 cm -1 The characteristic absorption peak of (2) is attributed to the pyridine molecule at +.>Adsorption of acid sites at 1455cm -1 Is due to adsorption of pyridine molecules at Lewis acid sites. The two-dimensional MFI molecular sieves with different struts introduced as provided in comparative examples 1-3 and example 1 all have lower Lewis acid site concentration and higher ∈compared to the two-dimensional MFI molecular sieve without struts provided in comparative example 2>The concentration of acid sites can prove that the method provided by the invention can be used for introducing the pillared between the sheets of the two-dimensional MFI molecular sieve, because the Lewis acid sites on the surface of the molecular sieve can react with the silicon hydroxyl groups on the surface of the molecular sieve in the pillared process to form Si-O-Si or Al-O-Si bonds, the defect sites on the surface of the molecular sieve are complete, and the Lewis acid sites are further converted into +.>Acid sites. The commercial molecular sieve provided in comparative example 4 has an ideal three-dimensional structure, maintaining the integrity of the crystal (i.e., fewer defective sites), thus +.>The acid site concentration is also higher. In FIG. 5 (b) -1616 cm -1 For the outer surface->Characteristic peaks of acid sites. As can be seen from FIG. 5 (b), the two-dimensional MFI molecular sieve without column provided in comparative example 2 of the present invention can expose more internal acid centers, thus the outer surface +.>The acid was higher than the rest of the molecular sieves, whereas in the two-dimensional MFI molecular sieves after the introduction of the column in example 1 and comparative examples 1 and 3, the outer surface +.>The number of acid sites is reduced. The commercial MFI molecular sieve provided in comparative example 4 is of three-dimensional microporous structure, so +.>The acid centers are located primarily within the framework of the molecular sieve, rather than on the exterior surface.
FIG. 6 is a graph showing the isothermal diagrams of nitrogen adsorption and desorption and pore size distribution of the two-dimensional MFI molecular sieves obtained in example 1 and comparative examples 1 to 4 according to the present invention, wherein (a) is the isothermal diagram of nitrogen adsorption and desorption and (b) is the pore size distribution. As can be seen from FIG. 6 (a), all the two-dimensional MFI molecular sieves provided by the present invention are in P/P 0 >The 0.5 hysteresis loop exhibited, which is mainly attributed to the mesopores produced by the stacking of the two-dimensional MFI lamellar structure, whereas the commercial MFI molecular sieve provided in comparative example 4 did not exhibit any hysteresis loop based on its typical three-dimensional microporous structure. Meanwhile, the crystallized pillared two-dimensional MFI molecular sieve provided in the embodiment 1 of the present invention has the highest total pore volume in all the molecular sieves of the present invention, which means that the molecular sieve provided in the embodiment 1 has the highest specific surface area. As can be seen from FIG. 6 (b), all the two-dimensional MFI molecular sieves provided by the present invention have a mesoporous structure (-4 nm), and the two-dimensional MFI molecular sieves provided by example 1 and comparative examples 1 and 3, in which the pillared two-dimensional MFI molecular sieves introduced by various means, all exhibit a narrower mesoporous pore size distribution (-4 nm), indicating that the pillared molecular sieves have a uniform mesoporous size, wherein the steam-phase pillared two-dimensional MFI molecular sieves provided by example 1 haveThe most mesoporous pore canal distribution exists.
FIG. 7 shows the MFI molecular sieves obtained in example 1 and comparative examples 1 to 4 of the present invention at 800 to 400cm -1 And 4000 to 1500cm -1 Wherein (a) is the MFI molecular sieve obtained in example 1 and comparative examples 1 to 4 in a range of 800 to 400cm -1 The MFI molecular sieves obtained in example 1 and comparative examples 1 to 4 were in the range of 4000 to 1500cm -1 Is a spectrum of infrared light of (a) is obtained. Testing molecular sieve at 800-400 cm -1 And 4000 to 1500cm -1 Is aimed at exploring the change of groups in molecular sieves. From FIG. 7, it can be observed that all samples were at 450cm -1 And 554cm -1 Two positions have obvious absorption peaks, and the two peaks are Si-O-Si telescopic vibration absorption peaks, which prove the successful synthesis of the MFI molecular sieve with the hierarchical pores. As can be seen from FIG. 7 (b), the molecular sieve obtained in example 1 was 450cm after the introduction of the crystallization column -1 And 554cm -1 The two infrared absorption peaks are wider, the characteristic peak intensity is higher, and the Si-OH group number is increased, because the column after crystallization column support is a crystalline molecular sieve structure instead of a pure amorphous silicon dioxide structure, and the T site (the joint of the column and the molecular sieve sheet layer) in the column is converted into Si-OH.
Fig. 8 is a TEM image of a crystallized pillared two-dimensional MFI molecular sieve obtained in example 1 of the present invention. From fig. 8, it can be seen that the crystallized pillared two-dimensional MFI molecular sieve after the template agent is removed by high-temperature calcination is successfully pillared in the crystallization pillared process, shows staggered stripes and white gaps, and proves that the crystallization pillared is successful and maintains the ordered multilayer assembly structure of the two-dimensional MFI molecular sieve.
FIG. 9 is a graph showing the comparison of the catalytic performance of the MFI molecular sieves obtained in example 1 and comparative examples 1 to 4 of the present invention in catalyzing the alkylation reaction of phenol with t-butanol, wherein (a) is a graph of the conversion of phenol and (b) is a graph of the selectivity to p-t-butylphenol.
FIG. 10 is a graph showing the comparison of the performance of the MFI molecular sieves obtained in example 1 and comparative example 3 of the present invention in catalyzing the alkylation of phenol with t-butanol after regeneration, wherein (a) is a graph of the conversion of phenol and (b) is a graph of the selectivity to p-t-butylphenol.
From FIGS. 9 to 10As can be seen, the crystallization pillared two-dimensional MFI molecular sieves provided by the embodiments of the present invention are used for catalyzing alkylation reaction of phenol and tert-butyl alcohol, and compared with the catalysis of various two-dimensional MFI molecular sieves provided by the comparative examples, the whole process has the highest reactant (phenol) conversion rate and the highest product (p-tert-butylphenol) selectivity, because the crystallization pillared introduced between the two-dimensional MFI molecular sieve sheets of the present invention can increase the pore channel number of micropores and increaseThe concentration of acid sites when molecular sieves are used to catalyze the reaction between organic substances>The acidic sites are active sites for catalytic reaction, so that the molecular sieve provided by the invention is used for catalyzing alkylation reaction between phenol and tertiary butanol, which is not only beneficial to effective contact (increase of active site number) of reactants and active sites, but also enhances internal diffusion (increase of micropore channels) of reactant molecules, thereby improving alkylation reaction activity. The molecular sieve provided in example 1 of the present invention still has excellent catalytic activity when the catalytic reaction has been carried out for 29 hours, which indicates that the crystallized pillared two-dimensional MFI molecular sieve provided in the present invention has excellent stability because water molecules are generated in the alkylation reaction of phenol and t-butanol, but the generation of water molecules does not lead to the hydrolysis of crystallized silica pillared in the molecular sieve.
It is to be understood that the above examples of the present invention are provided by way of illustration only and not by way of limitation of the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.
Claims (10)
1. The preparation method of the crystallized pillared two-dimensional MFI molecular sieve is characterized by comprising the following steps:
s1, placing a two-dimensional lamellar MFI molecular sieve which is not subjected to column support in silicon source steam for steam phase column support, and obtaining a steam phase column support type two-dimensional MFI molecular sieve after column support reaction is completed;
s2, sequentially placing the vapor-phase pillared two-dimensional MFI molecular sieve obtained in the step S1 into structure directing agent vapor and water vapor for crystallization, and obtaining the crystallized pillared two-dimensional MFI molecular sieve after crystallization is completed.
2. The method for preparing a crystallized pillared two-dimensional MFI molecular sieve according to claim 1, wherein the molar ratio of the structure directing agent in step S2 to the silicon source in step S1 is 1 (1.5-2).
3. The method for preparing a crystallized pillared two-dimensional MFI molecular sieve according to claim 1, wherein the crystallization temperature in the step S2 is 60-200 ℃.
4. The method for preparing a crystallized pillared two-dimensional MFI molecular sieve according to claim 1, wherein the total time of the crystallization in the step S2 is 36-60 h.
5. The method for preparing a crystallized pillared two-dimensional MFI molecular sieve according to claim 1, wherein the crystallized pillared two-dimensional MFI molecular sieve in step S2 is calcined after crystallization is completed, and the crystallized pillared two-dimensional MFI molecular sieve is placed in an aqueous solution containing ammonium groups for ion exchange after calcination is completed.
6. The method for preparing a crystallized pillared two-dimensional MFI molecular sieve according to claim 1, wherein the mass ratio of the pillared two-dimensional lamellar MFI molecular sieve to the silicon source in the step S1 is 1 (0.05-3.75).
7. A crystallized pillared two-dimensional MFI molecular sieve prepared by the method for preparing a crystallized pillared two-dimensional MFI molecular sieve according to any one of claims 1 to 6.
8. Use of the crystallized pillared two-dimensional MFI molecular sieve of claim 7 for catalyzing alkylation of phenol with tert-butanol.
9. The use according to claim 8, wherein the crystallization pillared two-dimensional MFI molecular sieve has a mass space velocity of 2-10 h between phenol and tert-butanol when catalyzing alkylation reaction of phenol and tert-butanol -1 。
10. The use according to claim 9, wherein the crystallized pillared two-dimensional MFI molecular sieve has a molar ratio of phenol to t-butanol of 1 (1-4) when catalyzing the alkylation reaction of phenol and t-butanol.
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