CN118080001A - Binder-free multistage pore-forming Beta molecular sieve catalyst and preparation method and application thereof - Google Patents
Binder-free multistage pore-forming Beta molecular sieve catalyst and preparation method and application thereof Download PDFInfo
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- CN118080001A CN118080001A CN202410218863.XA CN202410218863A CN118080001A CN 118080001 A CN118080001 A CN 118080001A CN 202410218863 A CN202410218863 A CN 202410218863A CN 118080001 A CN118080001 A CN 118080001A
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- molecular sieve
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- 239000002808 molecular sieve Substances 0.000 title claims abstract description 82
- 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 82
- 239000003054 catalyst Substances 0.000 title claims abstract description 61
- 238000002360 preparation method Methods 0.000 title abstract description 8
- 239000011230 binding agent Substances 0.000 claims abstract description 42
- 238000000034 method Methods 0.000 claims abstract description 26
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 25
- 238000006243 chemical reaction Methods 0.000 claims abstract description 22
- 239000011148 porous material Substances 0.000 claims abstract description 22
- 239000000843 powder Substances 0.000 claims abstract description 22
- 239000011259 mixed solution Substances 0.000 claims abstract description 14
- 238000009826 distribution Methods 0.000 claims abstract description 7
- 229920002521 macromolecule Polymers 0.000 claims abstract description 5
- VUMCUSHVMYIRMB-UHFFFAOYSA-N 1,3,5-tri(propan-2-yl)benzene Chemical compound CC(C)C1=CC(C(C)C)=CC(C(C)C)=C1 VUMCUSHVMYIRMB-UHFFFAOYSA-N 0.000 claims description 10
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 9
- 238000002425 crystallisation Methods 0.000 claims description 9
- 230000008025 crystallization Effects 0.000 claims description 9
- 238000004523 catalytic cracking Methods 0.000 claims description 7
- 238000000465 moulding Methods 0.000 claims description 6
- 238000001953 recrystallisation Methods 0.000 claims description 6
- LZZYPRNAOMGNLH-UHFFFAOYSA-M Cetrimonium bromide Chemical compound [Br-].CCCCCCCCCCCCCCCC[N+](C)(C)C LZZYPRNAOMGNLH-UHFFFAOYSA-M 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 5
- 238000001914 filtration Methods 0.000 claims description 4
- 229910002027 silica gel Inorganic materials 0.000 claims description 4
- 239000000741 silica gel Substances 0.000 claims description 4
- 150000003384 small molecules Chemical class 0.000 claims description 4
- 239000012321 sodium triacetoxyborohydride Substances 0.000 claims description 4
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 claims description 3
- HQABUPZFAYXKJW-UHFFFAOYSA-N butan-1-amine Chemical compound CCCCN HQABUPZFAYXKJW-UHFFFAOYSA-N 0.000 claims description 3
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 3
- 239000012265 solid product Substances 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 2
- 238000003756 stirring Methods 0.000 claims description 2
- HWCKGOZZJDHMNC-UHFFFAOYSA-M tetraethylammonium bromide Chemical compound [Br-].CC[N+](CC)(CC)CC HWCKGOZZJDHMNC-UHFFFAOYSA-M 0.000 claims description 2
- PLMFYJJFUUUCRZ-UHFFFAOYSA-M decyltrimethylammonium bromide Chemical compound [Br-].CCCCCCCCCC[N+](C)(C)C PLMFYJJFUUUCRZ-UHFFFAOYSA-M 0.000 claims 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 6
- 229910052710 silicon Inorganic materials 0.000 abstract description 6
- 239000010703 silicon Substances 0.000 abstract description 6
- 239000002994 raw material Substances 0.000 abstract description 4
- 230000005540 biological transmission Effects 0.000 abstract description 3
- 238000010335 hydrothermal treatment Methods 0.000 abstract description 3
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 238000004458 analytical method Methods 0.000 description 10
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 9
- 239000000047 product Substances 0.000 description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 239000003513 alkali Substances 0.000 description 5
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 5
- 238000001179 sorption measurement Methods 0.000 description 5
- 229910021536 Zeolite Inorganic materials 0.000 description 4
- XJWSAJYUBXQQDR-UHFFFAOYSA-M dodecyltrimethylammonium bromide Chemical compound [Br-].CCCCCCCCCCCC[N+](C)(C)C XJWSAJYUBXQQDR-UHFFFAOYSA-M 0.000 description 4
- 229940073455 tetraethylammonium hydroxide Drugs 0.000 description 4
- LRGJRHZIDJQFCL-UHFFFAOYSA-M tetraethylazanium;hydroxide Chemical compound [OH-].CC[N+](CC)(CC)CC LRGJRHZIDJQFCL-UHFFFAOYSA-M 0.000 description 4
- 239000010457 zeolite Substances 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 3
- 238000012512 characterization method Methods 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 238000005192 partition Methods 0.000 description 3
- 239000002243 precursor Substances 0.000 description 3
- 239000000376 reactant Substances 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 239000012018 catalyst precursor Substances 0.000 description 2
- 229910052593 corundum Inorganic materials 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 239000011343 solid material Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910001845 yogo sapphire Inorganic materials 0.000 description 2
- 239000005995 Aluminium silicate Substances 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 229910004283 SiO 4 Inorganic materials 0.000 description 1
- YAIQCYZCSGLAAN-UHFFFAOYSA-N [Si+4].[O-2].[Al+3] Chemical compound [Si+4].[O-2].[Al+3] YAIQCYZCSGLAAN-UHFFFAOYSA-N 0.000 description 1
- 230000029936 alkylation Effects 0.000 description 1
- 238000005804 alkylation reaction Methods 0.000 description 1
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 1
- 229910000323 aluminium silicate Inorganic materials 0.000 description 1
- 235000012211 aluminium silicate Nutrition 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
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 239000011363 dried mixture Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 1
- 238000005216 hydrothermal crystallization Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000006317 isomerization reaction Methods 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000643 oven drying Methods 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 238000004375 physisorption Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 238000002336 sorption--desorption measurement Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- CBXCPBUEXACCNR-UHFFFAOYSA-N tetraethylammonium Chemical compound CC[N+](CC)(CC)CC CBXCPBUEXACCNR-UHFFFAOYSA-N 0.000 description 1
- 238000010555 transalkylation reaction Methods 0.000 description 1
- SZEMGTQCPRNXEG-UHFFFAOYSA-M trimethyl(octadecyl)azanium;bromide Chemical compound [Br-].CCCCCCCCCCCCCCCCCC[N+](C)(C)C SZEMGTQCPRNXEG-UHFFFAOYSA-M 0.000 description 1
- 238000001132 ultrasonic dispersion Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
- 229920001285 xanthan gum Polymers 0.000 description 1
- 229940082509 xanthan gum Drugs 0.000 description 1
- 235000010493 xanthan gum Nutrition 0.000 description 1
- 239000000230 xanthan gum Substances 0.000 description 1
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- Catalysts (AREA)
Abstract
The invention provides a binder-free multistage pore-forming Beta molecular sieve catalyst, a preparation method and application thereof, wherein the mesoporous pore diameter distribution of the multistage pore-forming Beta molecular sieve catalyst is 2-10 nm, the percentage of the mesoporous accounts for 50-62.5% of the total ratio table, and the mechanical strength is 30-50 Nmm ‑1. Beta molecular sieve powder is used as a raw material, mixed with a binder for forming, then added into a template agent mixed solution containing two molecular sizes for hydrothermal treatment, an alkaline small molecular template agent is used for dissolving the binder, and a silicon source in the binder is used for assisting in reestablishing micropores, and a large molecular template agent is used for assisting in establishing mesopores and macropores, so that the binder-free multistage pore formed Beta molecular sieve catalyst is obtained. The formed Beta molecular sieve prepared by the method has good acidity and abundant mesopores, and provides a good transmission channel for macromolecular substance reaction. Meanwhile, the mechanical strength of the formed molecular sieve catalyst prepared by the method is obviously improved, and the catalyst is more beneficial to being applied to fixed bed reactions.
Description
Technical Field
The invention belongs to the technical field of molecular sieve forming, and relates to a binder-free multistage pore-forming Beta molecular sieve catalyst, and a preparation method and application thereof.
Background
The Beta molecular sieve is an aluminosilicate crystal which is formed by mutually connecting silicon (SiO 4) and aluminum (AlO 4) according to a certain rule, has a BEA topological structure, and consists of a twelve-membered ring pore system with the pore diameter of about 0.66 multiplied by 0.77nm and a Z-shaped curved pore with the pore diameter of about 0.56 multiplied by 0.56 nm. It has adjustable acidity and good hydrothermal stability, so it is widely used in alkylation, transalkylation, isomerization, cracking, catalytic cracking and other reactions.
However, in industrial applications, it is essential that the catalyst be shaped to provide a certain shape and mechanical strength. In the process of molecular sieve forming, some binders (such as silicon oxide, aluminum oxide, silicon aluminum oxide, kaolin and the like) are required to be added, so that the binders are mixed with the molecular sieve to form the catalyst with certain size, shape and mechanical strength. However, the addition of the inert binder reduces the content of the active components of the molecular sieve, and in addition, the addition of the binder forms the coating on the outer surface of the molecular sieve, which results in blocking of the pore channels of the molecular sieve, thereby affecting the diffusion of reactants and products and greatly affecting the activity of the formed Beta molecular sieve catalyst. Patent CN114471685A discloses a method for preparing a binder-free molded Beta molecular sieve. The preparation method of the catalyst comprises the following steps: tetraethyl ammonium hydroxide, white carbon black, aluminum sulfate octadecanoate and water are uniformly mixed, stirred uniformly in a closed container, and then uniformly mixed with amorphous silica, sodium metaaluminate and xanthan gum. And extruding and molding the obtained product to obtain a molding mixture. And then placing a porous partition board in the middle of a closed container, placing a dried mixture on the partition board, placing an aqueous solution of tetraethylammonium hydroxide under the partition board, and heating the mixture without contact with the aqueous solution of tetraethylammonium hydroxide to obtain the binder-free Beta molecular sieve catalyst. CN107511171a discloses a method for preparing a binder-free molded Beta molecular sieve catalyst. The preparation method of the catalyst comprises the following steps: and (3) contacting the Beta molecular sieve catalyst precursor with a solution which takes at least one compound in chemical reaction with the binder in the Beta molecular sieve catalyst precursor as a solute, and then separating, drying and roasting a solid product to obtain the binder-free Beta molecular sieve catalyst. CN105439164a discloses a preparation method of a binder-free molded Beta molecular sieve catalyst, which comprises the following steps: and (3) performing hydrothermal crystallization treatment on a precursor molded product containing a sodium source, a silicon source and an aluminum source in a tetraethylammonium ion aqueous solution to convert the precursor molded product into the binder-free Beta molded zeolite, wherein the precursor molded product comprises less than 80% of Beta zeolite. The technical emphasis is to remove the binder and improve the effective components of the molecular sieve, but the mass transfer performance of the Beta molecular sieve containing abundant micropores for macromolecular reactants is not improved.
The prior art can prepare the binder-free formed Beta molecular sieve catalyst. But can not effectively improve the mass transfer performance of macromolecular reactants, and a method for preparing the binder-free multistage pore-forming Beta molecular sieve catalyst by using the alkali post-treatment forming molecular sieve has not been reported yet.
Disclosure of Invention
In order to solve the technical problem of poor mass transfer performance of the existing non-bonded formed Beta molecular sieve catalyst, the application takes Beta molecular sieve powder as a raw material, and after the Beta molecular sieve powder is formed with a binder, the Beta molecular sieve powder is subjected to hydrothermal post-treatment by using a mixed solution of an alkaline small molecular template agent and a large molecular template agent, the binder is dissolved by the alkaline small molecular template agent, the secondary establishment of micropores is assisted by a silicon source in the binder, the mesoporous and macroporous establishment are assisted by the large molecular template agent, the dissolution-recrystallization process is realized by the binder, so that a large number of mesopores are generated on the formed catalyst, and the non-binder multistage pore formed Beta molecular sieve catalyst is obtained. The formed catalyst prepared by the method is different from the prior art in that the binder is converted into a molecular sieve crystalline phase, the formed molecular sieve pore channels are smooth, the acidity is improved, a large number of mesopores are introduced, a transmission channel which is favorable for the diffusion of macromolecular compounds is formed, and meanwhile, the mechanical strength of the obtained catalyst is higher than that of the traditional formed catalyst.
The technical scheme of the invention is as follows:
The catalyst has mesoporous pore size distribution of 2-10 nm, mesoporous specific surface of 200-500 m 2g-1, microporous specific surface of 200-300 m 2g-1, mesoporous content of 50-62.5%, mechanical strength of 30-50 Nmm -1 and 7-15 times higher than untreated catalyst.
According to still another aspect of the present application, there is provided a method for preparing a binder-free multistage pore-forming Beta molecular sieve catalyst, comprising at least the steps of:
(1) Mixing Beta molecular sieve powder and a binder, extruding strips for molding after uniformly mixing, and roasting to obtain a molded Beta molecular sieve catalyst containing the binder;
(2) Adding a formed Beta molecular sieve catalyst containing a binder into a mixed solution of an alkaline micromolecular template agent and a macromolecule template agent, uniformly stirring, transferring to a crystallization kettle, carrying out a dissolving-recrystallization reaction, filtering a solid product, and roasting to obtain the binder-free multistage pore formed Beta molecular sieve catalyst;
The alkaline small molecule template agent is at least one selected from TEAOH, n-butylamine and ethylenediamine; the macromolecular template agent is at least one selected from tetraethylammonium bromide, DTAB, CTAB and STAB.
The SiO 2/Al2O3 molar ratio of the Beta molecular sieve powder is 15-100.
Optionally, in step (1), the Beta molecular sieve powder is obtained by dehydrating Beta molecular sieve raw powder.
Optionally, in step (1), the binder is selected from at least one of silica sol, silica gel and solid silica gel.
Optionally, in the step (1), the mass ratio of the Beta molecular sieve powder to the binder is 1:1 to 9:1.
Optionally, in the step (2), the concentration of the alkaline small molecule template agent in the mixed solution is 0.01-1.0 mol/L.
Optionally, in the step (2), the concentration of the macromolecular template agent in the mixed solution is 0.01-1.0 mol/L.
Optionally, in the step (2), the mass ratio of the mixed solution to the Beta molecular sieve containing the binder is 1:1 to 10:1.
Optionally, in step (2), the conditions of the dissolution-recrystallization reaction are: the temperature is 120-180 ℃ and the time is 12-48 h.
According to a further aspect of the application, the application of the binder-free multistage pore-forming Beta molecular sieve catalyst obtained by the preparation method in the catalytic cracking reaction of 1,3, 5-triisopropylbenzene is provided.
In the present application, "TEAOH" refers to "tetraethylammonium hydroxide".
In the present application, "DTAB" means "dodecyltrimethylammonium bromide".
In the present application, "CTAB" means "cetyltrimethylammonium bromide".
In the present application, "STAB" refers to "octadecyl trimethyl ammonium bromide".
Compared with the existing binder treatment technology, the application has the following beneficial effects:
The Beta molecular sieve powder is used as a raw material, after the Beta molecular sieve powder is formed with a binder, the Beta molecular sieve powder is subjected to hydrothermal post-treatment by using a mixed solution of an alkaline small molecular template agent and a macromolecular template agent, the binder is dissolved by the alkaline small molecular template agent, the secondary establishment of micropores is assisted by a silicon source in the binder, the dissolution-recrystallization process is realized by the macromolecular template agent by using the silicon source in the binder to assist the establishment of mesopores and macropores, a large number of mesopores are generated on a formed catalyst, the original mechanical adhesion between crystals is changed into chemical bond connection, and the mechanical strength is greatly improved, so that the non-binder multistage pore formed Beta molecular sieve catalyst is obtained. The molded catalyst prepared by the method has the following characteristics: 1) The binder is converted into a molecular sieve crystalline phase, so that the formed molecular sieve pore channels are smooth, and the acidity is improved; 2) A large number of mesopores are introduced to form a transmission channel which is favorable for the diffusion of macromolecular compounds; 3) The mechanical strength of the catalyst is higher than that of the traditional formed catalyst, and the catalyst can meet the industrial production. The catalyst has the advantages of excellent performance in the catalytic cracking reaction of the 1,3, 5-triisopropylbenzene and good industrial practical application value.
Drawings
Fig. 1 is SEM of example sample p1# and comparative example sample d1#.
FIG. 2 is a graph showing pore size distribution of example samples P1#, P2#, P3#, and comparative example samples D1#.
Detailed Description
The present application is described in detail below with reference to examples, but the present application is not limited to these examples.
Unless otherwise indicated, all starting materials in the examples of the present application were purchased commercially. Unless otherwise indicated, the analytical methods in the examples employed both conventional settings of the instrument and conventional analytical methods.
In the examples of the present application, zeolite Beta molecular sieve raw powder was synthesized according to literature WADLINGER R L, kerr G T, rosinski E J.catalytic composition ofa crystalline zeolite [ J ]. US, 1967.
The analysis method in the embodiment of the application is as follows:
The relative crystallinity of the sample was calculated by X-ray diffraction (XRD) analysis of the sample: the analytical instrument used was a DX-2700B model X-ray diffractometer manufactured by DenbouYuan instruments Co. The measurement conditions were as follows: cukα fluorescence radiation, tube voltage 40kV, tube current 30mA, scanning step size 0.02 °, scanning range diffraction angle 2θ=5-40 °, scanning speed 6 °/min.
Characterization of nitrogen physisorption of samples: the analysis instrument is a JW-BK200 nitrogen physical adsorption instrument of Beijing micro-Gaobao science and technology Co. The analysis conditions were that 0.15g of the catalyst sample was put into a quartz tube, vacuum-treated at 350℃for 1.5 hours to remove moisture and impurities adsorbed by the molecular sieve material, and nitrogen adsorption/desorption experiments were performed at-195.7 ℃. The micropore and mesopore specific surface area of the sample was calculated using the Brunauer-Emmett-Teller (BET) equation, the internal and external surface areas and pore volumes of the molecular sieve sample were calculated by the t-plot method, and the total pore volume was calculated as the N 2 adsorption at a relative pressure P/P 0 = 0.99.
Ammonia-TPD test of samples: the analysis instrument is a PCA-1200 chemical adsorption analyzer of Beijing Piaode electronics, under the analysis condition that 0.15g of catalyst sample is put into a quartz tube, and is treated for 1h in helium atmosphere at 600 ℃, and ammonia adsorption experiment is carried out at 100 ℃ for 20min.
Scanning Electron Microscope (SEM) test of samples: the analyzer was an SU8220 scanning electron microscope manufactured by hitachi, japan, inc, under the following analysis conditions: accelerating voltage is 5kv, and ultrasonic dispersion is carried out in absolute ethyl alcohol before the sample test.
In the application, the dehydration pretreatment of the Beta molecular sieve raw powder adopts the following steps:
and (3) drying the synthesized Beta molecular sieve raw powder at 110 ℃, and roasting the Beta molecular sieve raw powder at 540 ℃ for 6 hours to obtain Beta molecular sieve powder, wherein the silicon-aluminum molar ratio is SiO 2/Al2O3 =25. The sample is marked as sample # 1.
Comparative example 1
Weighing 90g of sample No. 1 and 200g of 30wt% silica sol binder, uniformly mixing, extruding and molding. Oven-drying at 110deg.C, transferring to a muffle furnace, and calcining at 540 deg.C for 6 hr to obtain the final product. The sample is denoted as D1#.
Comparative example 2
25G of TEAOH solution with the concentration of 0.6mol/L is prepared and placed in a crystallization kettle, 5g of sample D1# is added into the crystallization kettle, the crystallization kettle is placed in a baking oven with the temperature of 150 ℃, and the crystallization kettle is taken out after standing for 24 hours. The solid material obtained was isolated by filtration, washed to neutrality with deionized water, dried in an oven at 110 ℃ for 12 hours, and transferred to a muffle furnace for 6 hours at 540 ℃. The sample was designated as D2#.
Example 1
25G of a mixed solution was prepared, wherein the concentration of TEAOH was 0.6mol/L and the concentration of CTAB was 0.6mol/L, the mixed solution was placed in a crystallization kettle, 5g of sample D1# was added thereto, the crystallization kettle was placed in an oven at 150℃and left standing for 24 hours, and then taken out. The solid material obtained was isolated by filtration, washed to neutrality with deionized water, dried in an oven at 110 ℃ for 12 hours, and transferred to a muffle furnace for 6 hours at 540 ℃. The sample was designated as P1#.
Examples 2 to 3
The procedure is as in example 1, except that the type of macromolecular template in the mixed solution is changed.
TABLE 1 examples under different macromolecular template classes
| Examples numbering | Sample numbering | Macromolecular template species |
| Example 2 | P2# | DTAB |
| Example 3 | P3# | STAB |
Examples 4 to 6
The procedure is as in example 1, except for the type and concentration of the base (alkaline small molecule template) during the hydrothermal treatment, the treatment temperature and the treatment time.
Table 2 examples under different hydrothermal treatment conditions
| Examples numbering | Sample numbering | Alkali type and concentration | Treatment temperature | Processing time |
| Example 4 | P4# | 0.6M ethylenediamine | 150℃ | 24h |
| Example 5 | P5# | 0.4M n-butylamine | 170℃ | 48h |
| Example 6 | P6# | 0.4MTEAOH | 150℃ | 32h |
Example 7
XRD, physical adsorption, ammonia-TPD and mechanical strength tests were performed on the samples of the above examples, and data are shown in Table 3 and FIG. 2, with sample # 1, comparative sample # D1, sample # D2, and example samples P1#, P2# and P3#. Compared with the Beta molecular sieve powder sample No. 1, the comparative sample No. D1 has the advantages that the relative crystallinity of the sample is greatly reduced after molding due to the addition of the binder, and meanwhile, the binder also plugs the pore channels of the molecular sieve, so that the total specific surface and the micropore specific surface of the sample are greatly reduced, and inter-crystalline mesopores between 10 nm and 30nm are formed. The binder can be dissolved and recrystallized by treating the molded sample with a single alkali, and the comparative sample D2# is obviously improved and recovered in relative crystallinity, pore distribution and acid amount, but the obtained sample is still a microporous molded catalyst and has weak mechanical strength. According to the method provided by the invention, a large amount of mesopores are generated in the crystallization process by adding the macromolecular template agent on the basis of single alkali treatment, so that the binder on the formed catalyst is converted and contains abundant micropores and mesopores, a certain acid amount is maintained, and the mechanical strength is improved compared with that of a comparative sample D1# which is not treated and a single alkali treatment formed sample D2#. Meanwhile, as can be seen from the pore size distribution of fig. 2, the intergranular mesopores brought by the binder disappear, and a series of binder-free multistage pore-forming Beta molecular sieve catalysts with pore size distribution can be obtained by using macromolecular template agents with different sizes.
Table 3 characterization results for each sample
Example 8
SEM characterization was performed on the above samples, taking example sample p1# and comparative sample d1# as examples, and SEM results thereof are shown in fig. 1. The results show that there is significant adhesive attachment to sample D1# and the surface is very rough. The sample P1# has obviously disappeared binder and smooth surface, and most of the sample is in a molecular sieve crystalline phase.
Example 9
The activity and selectivity of the catalyst prepared by the method are characterized by taking 1,3, 5-triisopropylbenzene as a reaction raw material through catalytic cracking reaction.
Wherein the conversion rate of 1,3, 5-triisopropylbenzene and the product selectivity are calculated based on the corrected chromatographic area of the peak of the chromatogram, wherein A i is the chromatographic area percentage of the product, A b is the residual chromatographic area percentage of 1,3, 5-triisopropylbenzene, and the calculation formula is as follows:
Conversion of 1,3, 5-triisopropylbenzene: c=100% -a b
Product selectivity: s i＝Ai/Cx100%
The reaction conditions are as follows: the reaction temperature is 300-350 ℃. The product analysis was carried out by gas chromatography using a hydrogen ion flame detector, and the catalytic cracking effect of the sample was as shown in Table 4 below. From the test results, it was found that the conversion rate of all catalysts and the selectivity to benzene increased with increasing temperature. Compared with the sample D1#, the adhesive of D2# is converted, but only has abundant micropores, the active site contacted with 1,3, 5-triisopropylbenzene is limited, and the conversion rate is slightly improved. While the sample P1# has a large amount of mesopores in the interior when the binder is converted, and the 1,3, 5-triisopropylbenzene can contact more active sites, so that the conversion rate of the catalyst is improved, and the selectivity of benzene is improved. Similarly, the catalysts P2# and P3# prepared by the method have the advantage that the conversion rate of 1,3, 5-triisopropylbenzene and the selectivity of benzene are improved.
Table 4 results of catalytic cracking reaction test for each sample
Claims (10)
1. A binder-free multistage pore-forming Beta molecular sieve catalyst is characterized in that: the mesoporous pore diameter distribution is 2-10 nm, the mesoporous ratio table is 200-500 m 2g-1, the micropore ratio table is 200-300 m 2g-1, the percentage of the total ratio table is 50% -62.5%, and the mechanical strength is 30-50 Nmm -1.
2. A method for preparing the binder-free multistage pore-forming Beta molecular sieve catalyst according to claim 1, which is characterized in that: at least comprises the following steps:
(1) Mixing Beta molecular sieve powder and a binder, extruding strips for molding after uniformly mixing, and roasting to obtain a molded Beta molecular sieve catalyst containing the binder;
(2) Adding a formed Beta molecular sieve catalyst containing a binder into a mixed solution of an alkaline micromolecular template agent and a macromolecule template agent, uniformly stirring, transferring to a crystallization kettle, carrying out a dissolving-recrystallization reaction, filtering a solid product, and roasting to obtain the binder-free multistage pore formed Beta molecular sieve catalyst;
The alkaline small molecule template agent is at least one selected from TEAOH, n-butylamine and ethylenediamine; the macromolecular template agent is at least one selected from tetraethylammonium bromide, DTAB, CTAB and STAB.
3. The method for preparing the binder-free multistage pore-forming Beta molecular sieve catalyst according to claim 2, which is characterized in that: in the step (1), the Beta molecular sieve powder is obtained by dehydrating Beta molecular sieve raw powder.
4. The method for preparing the binder-free multistage pore-forming Beta molecular sieve catalyst according to claim 2, which is characterized in that: in the step (1), the binder is at least one selected from silica sol, silica gel and solid silica gel.
5. The method for preparing the binder-free multistage pore-forming Beta molecular sieve catalyst according to claim 2, which is characterized in that: in the step (1), the mass ratio of the Beta molecular sieve powder to the binder is 1:1 to 9:1.
6. The method for preparing the binder-free multistage pore-forming Beta molecular sieve catalyst according to claim 2, which is characterized in that: in the step (2), the concentration of the alkaline small molecular template agent in the mixed solution is 0.01-1.0 mol/L.
7. The method for preparing the binder-free multistage pore-forming Beta molecular sieve catalyst according to claim 2, which is characterized in that: in the step (2), the concentration of the macromolecular template agent in the mixed solution is 0.01-1.0 mol/L.
8. The method for preparing the binder-free multistage pore-forming Beta molecular sieve catalyst according to claim 2, which is characterized in that: in the step (2), the mass ratio of the mixed solution to the Beta molecular sieve containing the binder is 1:1 to 10:1.
9. The method for preparing the binder-free multistage pore-forming Beta molecular sieve catalyst according to claim 2, which is characterized in that: in the step (2), the conditions of the dissolution-recrystallization reaction are: the temperature is 120-180 ℃ and the time is 12-48 h.
10. Use of the binderless multistage pore-forming Beta molecular sieve catalyst of claim 1 in a catalytic cracking reaction of 1,3, 5-triisopropylbenzene.
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