CN116002707A - MWW structure molecular sieve and preparation method thereof, and xylene isomerization catalyst and preparation method thereof - Google Patents
MWW structure molecular sieve and preparation method thereof, and xylene isomerization catalyst and preparation method thereof Download PDFInfo
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- CN116002707A CN116002707A CN202111231238.1A CN202111231238A CN116002707A CN 116002707 A CN116002707 A CN 116002707A CN 202111231238 A CN202111231238 A CN 202111231238A CN 116002707 A CN116002707 A CN 116002707A
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- 239000002808 molecular sieve Substances 0.000 title claims abstract description 141
- 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 141
- 239000003054 catalyst Substances 0.000 title claims abstract description 138
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 title claims abstract description 87
- 238000006317 isomerization reaction Methods 0.000 title claims abstract description 62
- 239000008096 xylene Substances 0.000 title claims abstract description 60
- 238000002360 preparation method Methods 0.000 title abstract description 12
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 81
- 239000007864 aqueous solution Substances 0.000 claims abstract description 47
- 238000000034 method Methods 0.000 claims abstract description 35
- 238000002156 mixing Methods 0.000 claims abstract description 31
- 101150111792 sda1 gene Proteins 0.000 claims abstract description 31
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 28
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 27
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 25
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 25
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 25
- 239000010703 silicon Substances 0.000 claims abstract description 25
- 238000005342 ion exchange Methods 0.000 claims abstract description 24
- 238000010335 hydrothermal treatment Methods 0.000 claims abstract description 17
- 229910000510 noble metal Inorganic materials 0.000 claims abstract description 14
- 230000003213 activating effect Effects 0.000 claims abstract description 9
- 239000011230 binding agent Substances 0.000 claims abstract description 9
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 48
- 239000000243 solution Substances 0.000 claims description 36
- -1 halogen anion Chemical class 0.000 claims description 30
- 239000002253 acid Substances 0.000 claims description 25
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 24
- 229910052697 platinum Inorganic materials 0.000 claims description 24
- 238000003756 stirring Methods 0.000 claims description 20
- 238000004519 manufacturing process Methods 0.000 claims description 19
- NNGAQKAUYDTUQR-UHFFFAOYSA-N cyclohexanimine Chemical compound N=C1CCCCC1 NNGAQKAUYDTUQR-UHFFFAOYSA-N 0.000 claims description 18
- 239000011734 sodium Substances 0.000 claims description 13
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 12
- 229910052736 halogen Inorganic materials 0.000 claims description 12
- 125000000217 alkyl group Chemical group 0.000 claims description 10
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 claims description 10
- 125000004432 carbon atom Chemical group C* 0.000 claims description 10
- 239000008367 deionised water Substances 0.000 claims description 10
- 229910021641 deionized water Inorganic materials 0.000 claims description 10
- 238000009826 distribution Methods 0.000 claims description 10
- 238000001035 drying Methods 0.000 claims description 10
- 238000005406 washing Methods 0.000 claims description 10
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 9
- 239000007787 solid Substances 0.000 claims description 9
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 claims description 8
- 238000002425 crystallisation Methods 0.000 claims description 8
- 230000008025 crystallization Effects 0.000 claims description 8
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical group [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 8
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 7
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- 238000001354 calcination Methods 0.000 claims description 6
- 235000019353 potassium silicate Nutrition 0.000 claims description 6
- 230000003068 static effect Effects 0.000 claims description 6
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 claims description 5
- 241000625836 Ochrolechia Species 0.000 claims description 5
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 claims description 5
- 239000007788 liquid Substances 0.000 claims description 5
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims description 5
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 claims description 3
- 238000005470 impregnation Methods 0.000 claims description 3
- 229910052763 palladium Inorganic materials 0.000 claims description 3
- 229910052703 rhodium Inorganic materials 0.000 claims description 3
- 239000010948 rhodium Substances 0.000 claims description 3
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 claims description 3
- 229910052707 ruthenium Inorganic materials 0.000 claims description 3
- 239000000377 silicon dioxide Substances 0.000 claims description 3
- 239000004115 Sodium Silicate Substances 0.000 claims description 2
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 2
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 abstract description 54
- 238000006243 chemical reaction Methods 0.000 abstract description 19
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 abstract description 8
- 241000446313 Lamella Species 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 18
- URLKBWYHVLBVBO-UHFFFAOYSA-N Para-Xylene Chemical group CC1=CC=C(C)C=C1 URLKBWYHVLBVBO-UHFFFAOYSA-N 0.000 description 16
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 15
- 239000000203 mixture Substances 0.000 description 13
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 11
- 229910052739 hydrogen Inorganic materials 0.000 description 11
- 239000001257 hydrogen Substances 0.000 description 11
- 239000002994 raw material Substances 0.000 description 11
- 230000003647 oxidation Effects 0.000 description 9
- 238000007254 oxidation reaction Methods 0.000 description 9
- 239000000843 powder Substances 0.000 description 8
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 239000000047 product Substances 0.000 description 5
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000000635 electron micrograph Methods 0.000 description 4
- IVSZLXZYQVIEFR-UHFFFAOYSA-N m-xylene Chemical group CC1=CC=CC(C)=C1 IVSZLXZYQVIEFR-UHFFFAOYSA-N 0.000 description 4
- 238000000465 moulding Methods 0.000 description 4
- 229910017604 nitric acid Inorganic materials 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 3
- 239000004215 Carbon black (E152) Substances 0.000 description 3
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 235000019270 ammonium chloride Nutrition 0.000 description 3
- 150000003863 ammonium salts Chemical class 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- PAWQVTBBRAZDMG-UHFFFAOYSA-N 2-(3-bromo-2-fluorophenyl)acetic acid Chemical compound OC(=O)CC1=CC=CC(Br)=C1F PAWQVTBBRAZDMG-UHFFFAOYSA-N 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 2
- 150000001768 cations Chemical class 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 239000012452 mother liquor Substances 0.000 description 2
- 239000010413 mother solution Substances 0.000 description 2
- 239000002060 nanoflake Substances 0.000 description 2
- 239000002135 nanosheet Substances 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 229910001415 sodium ion Inorganic materials 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 239000005995 Aluminium silicate Substances 0.000 description 1
- RWLIDTNLLKIXPX-UHFFFAOYSA-N C(C)C1=CC=CC=C1.C1(=CC=CC=C1)C.C(C)C1=CC=CC=C1.C1(=CC=CC=C1)C.C1=CC=CC=C1 Chemical compound C(C)C1=CC=CC=C1.C1(=CC=CC=C1)C.C(C)C1=CC=CC=C1.C1(=CC=CC=C1)C.C1=CC=CC=C1 RWLIDTNLLKIXPX-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 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 1
- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 description 1
- LGRFSURHDFAFJT-UHFFFAOYSA-N Phthalic anhydride Natural products C1=CC=C2C(=O)OC(=O)C2=C1 LGRFSURHDFAFJT-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 1
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 1
- 239000001166 ammonium sulphate Substances 0.000 description 1
- 235000011130 ammonium sulphate Nutrition 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 229910001423 beryllium ion Inorganic materials 0.000 description 1
- JHIWVOJDXOSYLW-UHFFFAOYSA-N butyl 2,2-difluorocyclopropane-1-carboxylate Chemical compound CCCCOC(=O)C1CC1(F)F JHIWVOJDXOSYLW-UHFFFAOYSA-N 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000005341 cation exchange Methods 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000006204 deethylation Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 150000004985 diamines Chemical class 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 238000006200 ethylation reaction Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 238000005984 hydrogenation 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
- 238000004898 kneading Methods 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 150000003738 xylenes Chemical class 0.000 description 1
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
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- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
- Catalysts (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
A method for preparing an MWW molecular sieve and a method for preparing a xylene isomerization catalyst by using the molecular sieve, and the MWW molecular sieve and the xylene isomerization catalyst prepared by the method. The preparation method of the molecular sieve comprises the steps of mixing and crystallizing a silicon source, an aluminum source, a first structure directing agent SDA1, a second structure directing agent SDA2 and water. The preparation method of the catalyst comprises (1) preparing MWW structure molecular sieve; (2) Ion-exchanging with a first structure directing agent SDA1 aqueous solution; (3) Carrying out hydrothermal treatment by using a second structure directing agent SDA2 aqueous solution; (4) supporting noble metal and activating. The MWW molecular sieve is nanometer lamellar molecular sieve, the silicon-aluminum ratio is 20-100, and the thickness of the lamella is 5-30 nanometers. The prepared dimethylbenzene isomerization catalyst comprises 5-70 mass% of MWW structure molecular sieve, 0.01-0.5 mass% of noble metal and the balance of alumina binder. The catalyst can be used for the dimethylbenzene isomerization reaction containing ethylbenzene, and has obviously improved ethylbenzene conversion capability and dimethylbenzene selectivity.
Description
Technical Field
The invention relates to a molecular sieve and a catalyst and a preparation method thereof, in particular to a method for preparing a nano lamellar MWW structure molecular sieve with a specific silicon-aluminum ratio, the MWW structure molecular sieve prepared by the method, a method for preparing a dimethylbenzene isomerization catalyst by adopting the molecular sieve, and the dimethylbenzene isomerization catalyst prepared by the method.
Background
Para-xylene (PX) is an important chemical raw material, and is mainly used for producing terephthalic acid, terephthalic acid diester, and phthalic anhydride, and is also used in the fields of paint, dye, pesticide, medicine, and the like. With the development of these industries, the demand for PX has grown rapidly. At present, the technology for increasing the yield of PX mainly comprises xylene isomerization, and the technology is an important means for converting meta-xylene and ortho-xylene with low utilization value into PX.
Through xylene isomerization reaction, the paraxylene in the product reaches or approaches to thermodynamic equilibrium value, the product can be separated from PX product by a separation device, and a small amount of light non-aromatic hydrocarbon, benzene, toluene and C are separated 9 + Heavy aromatics are separated out, and the rest C 8 The aromatic hydrocarbon material can be used as the raw material for isomerization for cyclic utilization.
Under the prior art conditions, the ethylbenzene and the dimethylbenzene are difficult and uneconomical to separate by adopting high-efficiency rectification or adsorption separation means, so that the ethylbenzene must be converted simultaneously in the dimethylbenzene isomerization process. There are two different target directions for ethylbenzene conversion: ethylbenzene is converted to xylenes and ethylbenzene is dealkylated to benzene. The economics of both directions depend on the composition of the raw materials, the energy consumption of the plant and the market conditions.
When the mass fraction of ethylbenzene in the raw material is lower, an ethylbenzene de-ethylation route is adopted, so that the reaction can be completed under the conditions of higher airspeed, lower hydrogen-hydrocarbon ratio and lower pressure, and the energy consumption is saved; when the mass fraction of ethylbenzene in the raw material is high, a deethylation route is adopted to produce a large amount of benzene as a byproduct, and when the price of benzene is low, the economy is obviously deteriorated, so that the high-ethylbenzene raw material adopts a route for converting ethylbenzene into dimethylbenzene. The reaction path for converting ethylbenzene into dimethylbenzene is more complex, the single-pass processing capacity of the catalyst is lower, and the required hydrogen-hydrocarbon ratio, temperature, pressure and other conditions are more severe. The molecular sieve types and acidity characteristics in the two routes of catalysts are also clearly different.
CN200910260072.9 is an ethylbenzene conversion type isomerization catalyst, and its active component is EUO type molecular sieve. The conversion catalyst can convert ethylbenzene into target product xylene, and the raw material resource is utilized to the maximum extent. With market changes, when the price of the carbon octaarene raw material is higher and the benzene product is excessive, the economy of the conversion process is better than that of the de-ethyl process. The major bottleneck limiting the economy of use of ethylbenzene conversion catalysts to date has been the lower per pass conversion of ethylbenzene, which increases the energy and material consumption of the materials during recycling.
The molecular sieve raw powder is usually Na-type, and needs to be subjected to ion exchange by ammonium salt, converted into ammonium type, and baked to decompose and convert ammonium cation into H-type, namely protonic acid (or called protonic acid)
Acid). In the art of xylene isomerization catalyst preparation, as shown in patent application CN200510080209.4, it is generally necessary to convert Na-type molecular sieves to H-type molecular sieves using an ion exchange process. Patent application CN200880120492.0 discloses an ion-exchanged xylene isomerization catalystThe preparation method of the catalyst is that ZSM-5 molecular sieve is preferred, and the formed carrier is subjected to ion exchange in solution. The solution used for the exchange generally comprises at least one source of hydrogen-forming cations, such as NH 4 + . The hydrogen-forming cations replace primarily the alkali metal cations to provide the hydrogen form of the molecular sieve component after calcination. Suitable compounds for use as solutes in aqueous solutions include ammonium nitrate, ammonium sulphate and/or ammonium chloride.
However, in view of cost and efficiency, there remains a need in the art to further increase the ethylbenzene conversion and xylene selectivity of the xylene isomerization catalyst.
Disclosure of Invention
Through a great number of experiments, the inventor can prepare the high-activity molecular sieve with a special structure by changing and optimizing the synthesis method of the molecular sieve serving as the active component of the catalyst; based on the molecular sieve, the catalyst with higher ethylbenzene conversion capability and xylene selectivity can be prepared by optimizing the ion exchange technology to regulate the acid center distribution.
Thus, in one aspect, the present invention provides a process for preparing a molecular sieve of MWW structure comprising mixing and crystallizing a silicon source, an aluminum source, a first structure directing agent SDA1, a second structure directing agent SDA2, and water, wherein the silicon source (as per SiO 2 Meter), aluminum source (according to Al 2 O 3 Calculated by weight) and water are added according to the molar ratio of SiO 2 :Al 2 O 3 :H 2 O=1:0.01-0.05:20-50; the mole ratio of the usage amount of the first structure directing agent SDA1 is SDA1 to SiO 2 =0.02 to 0.22; the second structure directing agent SDA2 is used in the molar ratio of SDA2 to SiO 2 ＝0.02～0.12。
In one embodiment of the method for preparing a MWW structured molecular sieve according to the invention, the silicon source is water glass; the aluminum source is one or more selected from aluminum sulfate, aluminum chloride and aluminum nitrate; the second structure directing agent SDA2 is cyclohexylimine; the first structure directing agent SDA1 is (R 1 ) 3 N + C n H 2n N + (R 2 ) 3 ·2X - Wherein R is 1 And R is 2 Are all alkyl groups of 1 to 4 carbon atoms, preferably methyl or ethyl, C n H 2n Is a linear alkyl group containing 2 to 10 carbon atoms, X - As the halogen anion, chloride or bromide is preferable. More specifically, SDA1 may be selected from dibromohexamethylhexane diamine, dichlorohexaethylbutane diamine, dibromohexamethylpentane diamine, dichlorohexamethyloctane diamine, dichlorohexapropyl decanediamine, and the like.
In another embodiment of the method for producing a molecular sieve of MWW structure according to the invention, the modulus (SiO 2 :Na 2 The molar ratio of O) is 2 to 4.
In another embodiment of the method for preparing a MWW structure molecular sieve according to the invention, the mixing comprises first dissolving a first structure directing agent in water to form a solution; adding an aluminum source under stirring, and stirring and mixing for 2-12 hours; adding a silicon source to form liquid sol, and stirring and mixing for 6-18 hours; and adding the second structure directing agent, and stirring and mixing uniformly.
In another embodiment of the process for preparing a molecular sieve of MWW structure according to the invention, the crystallization temperature is 140 to 190 ℃, preferably 165 to 175 ℃; the crystallization time is 20 to 120 hours, preferably 25 to 75 hours.
In another aspect, the present invention provides a molecular sieve of MWW structure prepared according to the method for preparing a molecular sieve of MWW structure of any of the preceding embodiments, which is a nano lamellar molecular sieve having a silica to alumina ratio of 20 to 100, preferably 25 to 50; and the thickness of the nano lamellar molecular sieve is 5-30 nanometers, preferably 10-20 nanometers.
In yet another aspect, the present invention provides a method of preparing a xylene isomerization catalyst, the method comprising the steps of:
(1) Mixing and crystallizing a silicon source, an aluminum source, a first structure directing agent SDA1, a second structure directing agent SDA2 and water to obtain an MWW structure molecular sieve, wherein the silicon source is sodium silicate; the aluminum source is one or more selected from aluminum sulfate, aluminum chloride and aluminum nitrate; the second structure directing agent SDA2 is cyclohexylimine; the first structure directing agent SDA1 is (R 1 ) 3 N + C n H 2n N + (R 2 ) 3 ·2X - Wherein R is 1 And R is 2 Are all alkyl groups of 1 to 4 carbon atoms, preferably methyl or ethyl, C n H 2n Is a linear alkyl group containing 2 to 10 carbon atoms, X - Is a halogen anion, preferably chloride or bromide;
(2) Ion exchange is carried out on the MWW structure molecular sieve prepared in the step (1) by using the aqueous solution of the first structure directing agent SDA1, deionized water is used for washing and drying after the ion exchange, and then the MWW structure molecular sieve is mixed with an alumina binder, molded and roasted to obtain a catalyst carrier;
(3) Carrying out hydrothermal treatment on the catalyst carrier prepared in the step (2) by using the aqueous solution of the second structure directing agent SDA2 as a steam source to obtain a catalyst carrier with optimized acid function distribution; and
(4) And (3) carrying out impregnation treatment on the catalyst with optimized acid function distribution prepared in the step (3) by using a solution containing noble metals, and activating and reducing to prepare the dimethylbenzene isomerization catalyst.
In one embodiment of the process for preparing a xylene isomerization catalyst according to the invention, the silicon source in step (1) (per SiO 2 Meter), aluminum source (according to Al 2 O 3 Calculated by weight) and water are added according to the molar ratio of SiO 2 :Al 2 O 3 :H 2 O=1:0.01-0.05:20-50; the mole ratio of the usage amount of the first structure directing agent SDA1 is SDA1 to SiO 2 =0.02 to 0.22; the second structure directing agent SDA2 is used in the molar ratio of SDA2 to SiO 2 ＝0.02～0.12。
In another embodiment of the method of preparing a xylene isomerization catalyst according to the invention, the mixing in step (1) comprises first dissolving a first structure directing agent in water to form a solution; adding an aluminum source under stirring, and stirring and mixing for 2-12 hours; adding a silicon source to form liquid sol, and stirring and mixing for 6-18 hours; and adding the second structure directing agent, and stirring and mixing uniformly.
In another embodiment of the process for preparing a xylene isomerization catalyst according to the invention, the crystallization in step (1) is carried out at a temperature of 140 to 190 ℃, preferably 165 to 175 ℃; the crystallization time is 20 to 120 hours, preferably 25 to 75 hours.
In another embodiment of the process for preparing a xylene isomerization catalyst according to the invention, the concentration of the aqueous solution of the first structure directing agent SDA1 in step (2) is 0.01 to 0.08mol/L, preferably 0.04 to 0.06mol/L; the liquid-solid ratio of the ion exchange is 5-30 mL/g molecular sieve, the temperature of the ion exchange is 50-90 ℃, and the times of the ion exchange are 2-4 times; na of MWW-structured molecular sieve of the obtained catalyst carrier 2 The molar content of O in the fully component oxide is 0.01 to 2.0%, preferably 0.1 to 0.4%.
In another embodiment of the process for preparing a xylene isomerization catalyst according to the invention, the drying in step (2) is carried out at 120℃for 8 to 24 hours, the calcination is carried out at 540℃for 2 to 24 hours, and the drying and calcination are carried out in a static atmosphere or at a volume space velocity of 50 to 500 hours -1 Is performed in a dynamic atmosphere.
In another embodiment of the process for preparing a xylene isomerization catalyst according to the invention, the concentration of the aqueous solution of the second structure directing agent SDA2 in step (3) is 0.01 to 0.08mol/L, preferably 0.04 to 0.06mol/L, the amount of solution is 5 to 30mL/g of catalyst support, the steam treatment temperature is 200 to 450 ℃, preferably 350 to 400 ℃, the treatment time is 3 to 6 hours.
In another embodiment of the process for preparing a xylene isomerization catalyst according to the invention, the noble metal in step (4) is platinum, palladium, rhodium or ruthenium, preferably platinum.
In another embodiment of the process for preparing a xylene isomerization catalyst according to the invention, the MWW structure molecular sieve produced in step (1) is a nanosheet molecular sieve having a silica to alumina ratio of 20 to 100, preferably 25 to 50; the thickness of the flakes is 5 to 30 nanometers, preferably 10 to 20 nanometers.
In another embodiment of the method for producing a xylene isomerization catalyst according to the invention, the content of MWW structure molecular sieve as acid catalytically active component in the xylene isomerization catalyst is 5 to 70 mass%, preferably 10 to 50 mass% of the total mass of the catalyst; the content of the noble metal is 0.01 to 0.5 mass% of the total mass of the catalyst, preferably 0.05 to 0.35 mass%; the rest components are alumina binder.
In yet another aspect, the present invention provides a xylene isomerization catalyst prepared according to the method of preparing a xylene isomerization catalyst of any of the preceding embodiments.
In one embodiment of the xylene isomerization catalyst according to the invention, the xylene isomerization catalyst comprises a nano flake MWW structured molecular sieve having a silicon to aluminum ratio of 20 to 100, preferably 25 to 50, and 0.01 to 0.5 mass%, preferably 0.05 to 0.35 mass% of noble metal.
In the method for preparing the MWW structure molecular sieve, two structure guiding agents (SDA 1 and SDA 2) are used, and the MWW structure molecular sieve flake with the silicon-aluminum ratio of 20-100 and the thickness of 5-30 nanometers is obtained. The MWW structure molecular sieve is formed by kneading a binding agent after ion exchange of a first structure guiding agent, and is subjected to hydrothermal treatment of a second structure guiding agent after forming, so that the acid function distribution of the catalyst carrier is optimized, and then the catalyst is obtained by loading a noble metal component, activating and reducing. When used in ethylbenzene-containing xylene isomerization reaction, the catalyst of the invention has significantly improved ethylbenzene conversion capability and xylene selectivity.
Drawings
FIG. 1 is an XRD spectrum of a Z-1 molecular sieve prepared according to example 1;
FIG. 2 is an XRD pattern of a Z-2 molecular sieve prepared according to example 2;
FIG. 3 is an SEM electron micrograph of a Z-1 molecular sieve prepared according to example 1; and
FIG. 4 is an SEM electron micrograph of a Z-2 molecular sieve prepared according to example 2.
Detailed Description
The present application will be described in further detail with reference to the accompanying drawings and examples. The features and advantages of the present application will become more apparent from the description.
In addition, the technical features described below in the different embodiments of the present application may be combined with each other as long as they do not collide with each other.
In one embodiment, the method for preparing a molecular sieve having MWW structure, i.e., the one-step method of MWW structure molecular sieve, according to the present invention comprises mixing and crystallizing a silicon source, an aluminum source, a first structure directing agent (SDA 1), a second structure directing agent (SDA 2), and water, wherein the silicon source (as per SiO 2 Meter), aluminum source (according to Al 2 O 3 Meter) and water according to SiO 2 :Al 2 O 3 :H 2 O=1:0.01-0.05:20-50, and the first structure directing agent SDA1 is used in a molar ratio of SDA1 to SiO 2 =0.02 to 0.22; the second structure directing agent SDA2 is used in a molar ratio SDA2 to SiO 2 ＝0.02～0.12。
In one embodiment, the silicon source may be water glass, preferably having a modulus of 2 to 4 (i.e., siO 2 :Na 2 Water glass with O mole ratio of 2-4).
In one embodiment, the aluminum source may be aluminum sulfate, aluminum chloride, aluminum nitrate, preferably aluminum sulfate.
In one embodiment, the first structure directing agent may be of formula (R 1 ) 3 N + C n H 2n N + (R 2 ) 3 ·2X - The indicated direct diamine dihalides, e.g. (CH) 3 ) 3 N + C 6 H 12 N + (CH 3 ) 3 ·2Cl - 、(CH 3 ) 3 N + C 6 H 12 N + (CH 3 ) 3 ·2Br - … … where R 1 And R is 2 Are each alkyl groups having 1 to 4 carbon atoms, preferably methyl or ethyl groups, n is 2 to 10, C n H 2n Is a linear alkyl group containing 2 to 10 carbon atoms, X - As the halogen anion, chloride or bromide is preferable.
In one embodiment, the second structure directing agent may be cyclohexylimine … …, preferably cyclohexylimine.
More specifically, a first structure directing agent is first dissolved in water to form a solution; slowly adding an aluminum source under stirring, and stirring and mixing for 2-12 hours; slowly adding a silicon source to form liquid sol, and stirring and mixing for 6-18 hours to ensure that the sol phase state is uniform; and adding a second structure directing agent into the sol, and stirring and mixing uniformly to complete the mixing of the raw materials. The mixture is then crystallized at a temperature of 140 to 190℃for 20 to 120 hours, preferably at a temperature of 165 to 175℃for 25 to 75 hours.
The molecular sieve with MWW structure is nano lamellar molecular sieve, and the thickness dimension is 5-30 nm, preferably 10-20 nm; the silicon-aluminum ratio is 20 to 100, preferably 25 to 50.
The xylene isomerization catalyst of the invention comprises the molecular sieve with an MWW structure as an active component, and provides an acid site for xylene isomerization reaction, and also provides an acid site for ethylbenzene conversion to xylene. In general, as an active component of the xylene isomerization catalyst of the present invention, the molecular sieve having an MWW structure may be contained in an amount of 10 to 50 mass% of the entire catalyst.
In one embodiment, a method of preparing a xylene isomerization catalyst according to the invention comprises the steps of:
(1) Mixing and crystallizing a silicon source, an aluminum source, a first structure directing agent SDA1, a second structure directing agent SDA2 and water to prepare an MWW structure molecular sieve;
(2) Ion exchange is carried out on the MWW structure molecular sieve prepared in the step (1) by using the aqueous solution of the first structure directing agent SDA1, deionized water is used for washing and drying after the ion exchange, and then the MWW structure molecular sieve is mixed with an alumina binder, molded and roasted to obtain a catalyst carrier;
(3) Carrying out hydrothermal treatment on the catalyst carrier prepared in the step (2) by using the aqueous solution of the second structure directing agent SDA2 as a steam source to obtain a catalyst carrier with optimized acid function distribution; and
(4) And (3) carrying out impregnation treatment on the catalyst with optimized acid function distribution prepared in the step (3) by using a solution containing noble metals, and activating and reducing to prepare the dimethylbenzene isomerization catalyst.
Specifically, in the step (2) of the catalyst preparation method, the MWW structure nano-sheet molecular sieve raw powder is subjected to ion exchange by using an aqueous solution of a first structure directing agent SDA1, wherein the concentration of the solution is 0.01-0.08 mol/L, preferably 0.04-0.06 mol/L, the exchange liquid-solid ratio is 5-30 mL/g of molecular sieve, the exchange temperature is 50-90 ℃, and the exchange times are 2-4 times; the exchanged molecular sieve is washed for a plurality of times by using excessive deionized water until no halogen anions are detected in the eluate, and the pH range is 6-8. Na of MWW structure molecular sieve after washing 2 The molar content of O is 0.01-2.0%, preferably 0.1-0.4%. And drying the fully washed MWW structure molecular sieve raw powder for 8-24 hours at 120 ℃, wherein the drying can be performed in static atmosphere without air flow or in dynamic atmosphere with volume airspeed of 50-500. The dried molecular sieve can be molded by a conventional method. Drying the molded carrier at 120 ℃ for 8-24 hours, and roasting the molded carrier at 540 ℃ for 2-24 hours in air. The calcination may be carried out in a static atmosphere without air flow or in a dynamic atmosphere with a volume space velocity of 50 to 500.
Specifically, in the step (3) of the catalyst preparation method, the molded catalyst carrier containing the MWW structure molecular sieve and the alumina is subjected to acid function distribution optimization treatment, namely, an aqueous solution of a second structure directing agent SDA2 is used as a steam source for hydrothermal treatment, the concentration of the SDA2 aqueous solution is 0.01-0.08 mol/L, preferably 0.04-0.06 mol/L, the solution dosage is 5-30 mL/g carrier, the steam treatment temperature is 200-450 ℃, preferably 350-400 ℃, and the treatment time is 3-6 h.
NH in ammonium salts is generally used 4 + The cation exchanges sodium molecular sieve material, but the volume of ammonium cation is smaller, all sodium ions are exchanged into ammonium ions in the exchange process in a non-selective way, the cyclohexylimine is selected as an ion exchanger, and the cyclohexylimine can not enter into pore channels in a deeper part of the molecular sieve due to the larger molecular size of the cyclohexylimine, so that the amine ions only exchange sodium ions at the outer surface and the pore opening of the molecular sieve through shape selective effect, are converted into amine ions, and are converted into H ions in the subsequent roasting, thereby formingAn acid center.
It is generally believed that the aluminum ions on the molecular sieve are displaced and chemically modulated during the hydrothermal treatment, and that the migrated portion of the aluminum ions can be ion exchanged and shape-selected again if an organic amine having a shape selective effect can be added simultaneously during the hydrothermal treatment.
The formed catalyst carrier after the acid function distribution optimization treatment can be impregnated with noble metal and subjected to activation reduction according to a conventional method, so that the catalyst of the invention is obtained.
In one embodiment, the noble metal in step (4) of the method of preparing a xylene isomerization catalyst according to the invention is platinum, palladium, rhodium or ruthenium, preferably platinum.
In one embodiment, the catalyst according to the present invention comprises a nano-lamellar MWW structure molecular sieve as an acidic active component and alumina as a binder, wherein the MWW structure molecular sieve is contained in an amount of 10 to 50 mass%, and the remaining components are alumina binder; the catalyst of the present invention is also supported with 0.05 to 0.35 mass% of a noble metal.
The catalyst prepared by the method can be applied to the xylene isomerization reaction containing ethylbenzene. Ethylbenzene-containing xylene isomerization is the process of contacting a catalyst in the presence of hydrogen. When the mass fraction of ethylbenzene in the raw material is in the range of 8-20%, controlling the weight hourly space velocity of the catalyst to be 3-8 h -1 The pressure is 0.4-1.6 MPa, the temperature is 300-350 ℃, and the molar ratio of hydrogen to hydrocarbon is 2.0-4.5. Compared with the existing catalyst, the ethylbenzene conversion capability and xylene selectivity of the catalyst are improved.
The catalyst performance was assessed as follows:
isomerization equilibrium achievement rate:
xylene yield:
ethylbenzene conversion:
the invention is further illustrated by the following examples, but is not limited thereto.
Examples
The following examples synthesize Na-type raw powders of nano-flake molecular sieves of MWW structure.
Example 1
A2L reactor was charged with 450mL of a silicon source (water glass, concentration: 24w%, modulus: 3.1), 20.2g of an aluminum source (aluminum sulfate), and (CH) 3 ) 3 N + C 6 H 12 N + (CH 3 ) 3 ·2Cl - As a first structure directing agent, the amount added was 4.1g; the cyclohexylimine is taken as a second structure directing agent, the addition amount is 9.0g, and the molar ratio of each material is Na 2 O:SiO 2 :Al 2 O 3 :SDA1:SDA2:H 2 O=0.32:1:0.04:0.02:0.12:25. The synthesis temperature was 175℃and the synthesis time was 35 hours.
Thus, the nano lamellar molecular sieve with a Na-type MWW structure is marked as Z-1, and the silicon-aluminum ratio is 25. The XRD diffraction pattern of the obtained molecular sieve Z-1 is shown in figure 1, and the molecular sieve has MWW structural characteristic peaks in the range of 5-50 degrees. SEM electron micrograph of the obtained molecular sieve Z-1 is shown in FIG. 3, and the molecular sieve Z-1 has a nano lamellar structure as shown in the figure.
Example 2
A2L reactor was charged with 450mL of a silicon source (water glass, concentration: 24w%, modulus: 3.1), 10.1g of an aluminum source (aluminum sulfate), and (CH) 3 ) 3 N + C 6 H 12 N + (CH 3 ) 3 ·2Br - As a first structure directing agent, the amount added was 60.4g; the cyclohexylimine is taken as a second structure directing agent, the addition amount is 1.5g, and the molar ratio of each material is Na 2 O:SiO 2 :Al 2 O 3 :SDA1:SDA2:H 2 O=0.32:1:0.02:0.22:0.02:35. The synthesis temperature was 165℃and the synthesis time was 25 hours.
Thus, the nano lamellar molecular sieve with a Na-type MWW structure, which is denoted as Z-2, is prepared, and the silicon-aluminum ratio is 50. The XRD diffraction pattern of the obtained molecular sieve Z-2 is shown in figure 2, and the molecular sieve has MWW structural characteristic peaks in the range of 5-50 degrees. SEM electron micrograph of the obtained molecular sieve Z-2 is shown in FIG. 4, which shows a nano lamellar structure.
The following comparative examples prepared conventional xylene isomerization catalysts.
Comparative example 1
3g of commercial Eu-1 molecular sieve (supplied by Kaolin catalyst Co., ltd.) powder with a silicon-aluminum ratio of 30 is taken, ion exchange is carried out with 50ml of 0.05mol/L ammonium chloride aqueous solution at 90 ℃ for 2 hours X2 times, and the solution is washed until no chloride ions are detected in the mother solution, and the pH range is 6-8. The fully washed molecular sieve is dried for 8 hours at 120 ℃ in static atmosphere without air flow. The dried molecular sieve is fully and uniformly mixed with 17g of alumina, 20ml of 3% nitric acid aqueous solution is added for mixing to prepare a viscous mixture, and the mixture is extruded into strips for molding. The bars were dried at 120℃for 6 hours, then pelletized and calcined at 540℃for 4 hours. The hydrothermal treatment is carried out by using water vapor, the treatment temperature is 350 ℃, and the treatment time is 6 hours. The treated carrier was impregnated with 20ml of an aqueous solution of chloroplatinic acid containing 0.05g of platinum, and dried at 120℃to prepare a catalyst containing 0.25% by mass of platinum. Then activating in air to prepare an oxidation state catalyst, and reducing in hydrogen for 4 hours to prepare a comparative catalyst D-1.
Comparative example 2
Comparative catalyst D-2 was prepared as in comparative example 1, except that 9g of commercial MOR molecular sieve (supplied by Fushun catalyst Co., ltd.) powder having a silica-alumina ratio of 12 was used, and 50ml of a 0.05mol/L aqueous solution of dibromohexamethylhexane diamine was subjected to ion exchange at 80℃for 2 hours X3 times, and washed until no chloride ion was detected in the mother liquor, and the pH range was 6 to 8. The fully washed molecular sieve is dried for 24 hours at 120 ℃ in a dynamic atmosphere with a volume space velocity of 500. The dried molecular sieve is fully and uniformly mixed with 11g of alumina, 20ml of 5% nitric acid aqueous solution is added for mixing to prepare a viscous mixture, and the mixture is extruded into strips for molding. The bars were dried at 120℃for 12 hours, then pelletized and calcined at 540℃for 12 hours. And (3) performing hydrothermal treatment by using an aqueous solution of the second structure directing agent cyclohexylimine as a steam source, wherein the concentration of the solution is 0.06mol/L, the solution dosage is 600mL, the steam treatment temperature is 400 ℃, and the treatment time is 3 hours. The treated carrier was impregnated with 20ml of an aqueous solution of chloroplatinic acid containing 0.35g of platinum, and dried at 120℃to prepare a catalyst containing 0.35% by mass of platinum. Then activating in air to prepare an oxidation state catalyst, and reducing in hydrogen for 4 hours to prepare a comparative catalyst D-2.
Comparative example 3
Comparative catalyst D-3 was prepared in the same manner as in comparative example 1 except that 3g of the powder of molecular sieve Z-1 of Na-type MWW structure having a silica-alumina ratio of 25 synthesized in example 1 was used, and ion-exchange was carried out with 50ml of an aqueous solution of 0.05mol/L ammonium chloride at 90℃for 2 hours X4 times, and washed until no chloride ion was detected in the mother liquor, and the pH range was 6 to 8. The fully washed molecular sieve was dried at 120 ℃ for 16 hours in a static atmosphere without air flow. The dried molecular sieve is fully and uniformly mixed with 17g of alumina, 15ml of 4% nitric acid aqueous solution is added for mixing to prepare a viscous mixture, and the mixture is extruded into strips for molding. The bars were dried at 120℃for 16 hours, then pelletized and calcined at 540℃for 10 hours. The treated carrier was impregnated with 20ml of an aqueous solution of chloroplatinic acid containing 0.05g of platinum, and dried at 120℃to prepare a catalyst containing 0.05% by mass of platinum. Then activating in air to prepare an oxidation state catalyst, and reducing in hydrogen for 4 hours to prepare a comparative catalyst D-3.
Comparative example 4
9g of the Na-MWW molecular sieve Z-2 powder with the silicon-aluminum ratio of 50 synthesized in the example 2 is taken, 50ml of 0.04mol/L ammonium nitrate aqueous solution is used for ion exchange for 2 hours X3 times at 50 ℃, and the solution is washed until no chloride ions are detected in the mother solution, and the pH range is 6-8. The fully washed molecular sieve is dried for 18 hours at 120 ℃ in a dynamic atmosphere with the volume space velocity of 50. The dried molecular sieve is fully and uniformly mixed with 11g of alumina, 20ml of 4% nitric acid aqueous solution is added for mixing to prepare a viscous mixture, and the mixture is extruded into strips for molding. The bars were dried at 120℃for 24 hours, then pelletized and calcined at 540℃for 12 hours. The aqueous solution was used as a steam source for hydrothermal treatment at a temperature of 350℃for a treatment time of 6 hours. The treated carrier was impregnated with 20ml of an aqueous solution of chloroplatinic acid containing 0.35g of platinum, and dried at 120℃to prepare a catalyst containing 0.35% by mass of platinum. Then activating in air to prepare an oxidation state catalyst, and reducing in hydrogen for 4 hours to prepare a comparative catalyst D-4.
The xylene isomerization catalyst of the present invention is prepared in the following examples.
Example 3
Catalyst C-1 according to the invention was prepared in the manner of comparative example 3, except that the molecular sieve was ion-exchanged with an aqueous solution of dibromohexamethyl-hexane diamine as the first structure directing agent, the concentration of the solution being 0.06mol/L, the exchange liquid-solid ratio being 30mL/g molecular sieve, the exchange temperature being 90℃and the number of exchanges being 4; the exchanged molecular sieve is washed for a plurality of times by using excessive deionized water until no halogen anions are detected in the eluate, and the pH range is 6-8. Na of MWW structure molecular sieve after washing 2 The molar content of O was 0.4%. The molded carrier is subjected to hydrothermal treatment by using an aqueous solution of a second structure directing agent cyclohexylimine as a steam source, wherein the concentration of the solution is 0.04mol/L, the dosage of the solution is 5mL/g of the carrier, the steam treatment temperature is 350 ℃, and the treatment time is 6 hours. Platinum was impregnated by 0.25 mass% in the same manner as in comparative example 1, and calcined for activation reduction.
Example 4
Catalyst C-2 according to the invention was prepared as in example 3, except that 9g of the Na-MWW structure molecular sieve Z-2 having a silica-alumina ratio of 50 synthesized in example 2 was used for the molecular sieve, ion exchange was performed using an aqueous solution of the first structure directing agent, dichlorohexaethylbutanediamine, the concentration of the solution was 0.04mol/L, the exchange liquid-solid ratio was 5mL/g of the molecular sieve, the exchange temperature was 50℃and the number of exchanges was 2; the exchanged molecular sieve is washed for a plurality of times by using excessive deionized water until no halogen anions are detected in the eluate, and the pH range is 6-8. Na of MWW structure molecular sieve after washing 2 The molar content of O was 0.2%. The exchanged molecular sieve is mixed with 11g of alumina and extruded to form strips. The molded carrier is subjected to hydrothermal treatment by using an aqueous solution of a second structure directing agent cyclohexylimine as a steam source, wherein the concentration of the solution is 0.06mol/L, the dosage of the solution is 30mL/g of the carrier, the steam treatment temperature is 400 ℃, and the treatment time is 3 hours. The treated carrier is immersed in 20ml of chloroplatinic acid aqueous solution containing 0.15g platinum, and dried at 120 ℃ to prepare the carrier containing platinumPlatinum 0.15 mass% of a catalyst. And then activated in air to prepare an oxidation state catalyst, and reduced in hydrogen for 4 hours to prepare the catalyst C-2 according to the invention.
Example 5
Catalyst C-3 according to the invention was prepared as in example 4, except that 3g of the Na-MWW structure molecular sieve Z-2 having a silica-alumina ratio of 50 synthesized in example 2 was taken, ion-exchanged with an aqueous solution of the first structure directing agent, dichlorohexaethylbutanediamine, the concentration of the solution being 0.06mol/L, the exchange liquid-solid ratio being 20mL/g molecular sieve, the exchange temperature being 80℃and the number of exchanges being 3; the exchanged molecular sieve is washed for a plurality of times by using excessive deionized water until no halogen anions are detected in the eluate, and the pH range is 6-8. Na of MWW structure molecular sieve after washing 2 The molar content of O was 0.3%. The exchanged molecular sieve is mixed with 17g of alumina and extruded to form strips. The molded carrier is subjected to hydrothermal treatment by using an aqueous solution of a second structure directing agent cyclohexylimine as a steam source, wherein the concentration of the solution is 0.05mol/L, the dosage of the solution is 5mL/g of the carrier, the steam treatment temperature is 370 ℃, and the treatment time is 4 hours. The treated carrier was impregnated with 20ml of an aqueous solution of chloroplatinic acid containing 0.30g of platinum, and dried at 120℃to prepare a catalyst containing 0.30% by mass of platinum. And then activated in air to prepare an oxidation state catalyst, and reduced in hydrogen for 4 hours to prepare the catalyst C-3 according to the invention.
Example 6
Catalyst C-4 according to the invention was prepared as in example 4, except that 6g of the Na-MWW structure molecular sieve Z-2 having a silica-alumina ratio of 50 synthesized in example 2 was ion-exchanged with an aqueous solution of dibromohexamethylpentane diamine as the first structure directing agent, the concentration of the solution was 0.04mol/L, the exchange liquid-solid ratio was 25mL/g of molecular sieve, the exchange temperature was 70℃and the number of exchanges was 4; the exchanged molecular sieve is washed for a plurality of times by using excessive deionized water until no halogen anions are detected in the eluate, and the pH range is 6-8. Na of MWW structure molecular sieve after washing 2 The O molar content was 0.25%. The exchanged molecular sieve is mixed with 14g of alumina and extruded to form strips. The molded carrier uses the aqueous solution of the second structure directing agent cyclohexylimine as steamThe source was hydrothermally treated with a solution concentration of 0.04mol/L and a solution dosage of 15mL/g carrier at a steam treatment temperature of 350℃for 6 hours. The treated carrier was impregnated with 20ml of an aqueous solution of chloroplatinic acid containing 0.25g of platinum, and dried at 120℃to prepare a catalyst containing 0.25% by mass of platinum. And then activated in air to prepare an oxidation state catalyst, and reduced in hydrogen for 4 hours to prepare the catalyst C-4 according to the invention.
Example 7
Catalyst C-5 according to the invention was prepared as in example 4, except that 8g of the Na-MWW structure molecular sieve Z-2 having a Si/Al ratio of 50 synthesized in example 2 was taken, ion-exchanged with an aqueous solution of the first structure directing agent, dichloro-hexamethyl-octanediamine, the concentration of the solution being 0.055mol/L, the exchange liquid-solid ratio being 15mL/g molecular sieve, the exchange temperature being 90℃and the number of exchanges being 4 times; the exchanged molecular sieve is washed for a plurality of times by using excessive deionized water until no halogen anions are detected in the eluate, and the pH range is 6-8. Na of MWW structure molecular sieve after washing 2 The molar content of O was 0.4%. The exchanged molecular sieve is mixed with 12g of alumina and extruded to form strips. The molded carrier is subjected to hydrothermal treatment by using an aqueous solution of a second structure directing agent cyclohexylimine as a steam source, wherein the concentration of the solution is 0.04mol/L, the dosage of the solution is 15mL/g of the carrier, the steam treatment temperature is 350 ℃, and the treatment time is 6 hours. The treated carrier was impregnated with 20ml of an aqueous solution of chloroplatinic acid containing 0.20g of platinum, and dried at 120℃to prepare a catalyst containing 0.20% by mass of platinum. And then activated in air to prepare an oxidation state catalyst, and reduced in hydrogen for 4 hours to prepare the catalyst C-5 according to the invention.
Example 8
Catalyst C-6 according to the invention was prepared as in example 4, except that 10g of the Na-MWW structure molecular sieve Z-2 having a silica-alumina ratio of 50 synthesized in example 2 was ion-exchanged with an aqueous solution of dibromohexamethylpentane diamine as the first structure directing agent, the concentration of the solution was 0.06mol/L, the exchange liquid-solid ratio was 25mL/g of molecular sieve, the exchange temperature was 70℃and the number of exchanges was 4; the exchanged molecular sieve is washed several times with excess deionized water until the eluate is free of halogen anionsSub-detection, pH range is 6-8. Na of MWW structure molecular sieve after washing 2 The O molar content was 0.25%. The exchanged molecular sieve is mixed with 10g of alumina and extruded to form strips. The molded carrier is subjected to hydrothermal treatment by using an aqueous solution of a second structure directing agent cyclohexylimine as a steam source, wherein the concentration of the solution is 0.04mol/L, the dosage of the solution is 15mL/g of the carrier, the steam treatment temperature is 350 ℃, and the treatment time is 6 hours. The treated carrier was impregnated with 20ml of an aqueous solution of chloroplatinic acid containing 0.15g of platinum, and dried at 120℃to prepare a catalyst containing 0.15% by mass of platinum. And then activated in air to prepare an oxidation state catalyst, and reduced in hydrogen for 4 hours to prepare the catalyst C-6 according to the invention.
The following examples illustrate the use of the xylene isomerization catalysts of the present invention.
Example 9
The catalyst performance was evaluated on a continuous flow fixed bed mini-type hydrogenation apparatus charged with 2g of the xylene isomerization catalyst prepared in the above examples and comparative examples using an industrial xylene isomerization feedstock. The composition of the raw materials used in the reaction, the evaluation technological parameters, the characteristics of the catalysts of each example and the reaction results are shown in the following table.
TABLE 1 Industrial xylene isomerization feed composition
| Composition of raw materials | C 8 Naphthene | Benzene | Toluene (toluene) | Ethylbenzene (ethylbenzene) | Para-xylene | Meta-xylene | Ortho-xylene |
| wt％ | 5.62 | 0.02 | 1.03 | 17.16 | 0.49 | 53.36 | 22.32 |
TABLE 2 catalysts prepared in examples and comparative examples and reaction Properties
As can be seen from comparing the results of the above examples and comparative examples, according to the catalyst preparation method of the present invention, using the nano-lamellar molecular sieve of MWW structure and using the structure directing agent SDA1 as an ion exchanger and the structure directing agent SDA2 as a steam treating agent, the prepared catalyst has higher ethylbenzene conversion activity and xylene selectivity than the conventional catalyst prepared using the EUO or MOR molecular sieve, or the catalyst prepared using only conventional ammonium salt ion exchange and hydrothermal treatment means.
The invention has been described above in connection with preferred embodiments, which are, however, merely exemplary and illustrative. On the basis, the invention can be subjected to various substitutions and improvements, and all the substitutions and improvements fall into the protection scope of the invention.
Claims (17)
1. A method of preparing a MWW structured molecular sieve comprising mixing and crystallizing a silicon source, an aluminum source, a first structure directing agent SDA1, a second structure directing agent SDA2, and water, wherein the silicon source (as per SiO 2 Meter), aluminum source (according to Al 2 O 3 Calculated by weight) and water are added according to the molar ratio of SiO 2 :Al 2 O 3 :H 2 O=1:0.01-0.05:20-50; the mole ratio of the usage amount of the first structure directing agent SDA1 is SDA1 to SiO 2 =0.02 to 0.22; the second structure directing agent SDA2 is used in the molar ratio of SDA2 to SiO 2 ＝0.02～0.12。
2. The process for producing a molecular sieve of MWW structure according to claim 1, wherein the silicon source is water glass; the aluminum source is one or more selected from aluminum sulfate, aluminum chloride and aluminum nitrate; the second structure directing agent SDA2 is cyclohexylimine; the first structure directing agent SDA1 is (R 1 ) 3 N + C n H 2n N + (R 2 ) 3 ·2X - Wherein R is 1 And R is 2 Are all alkyl groups of 1 to 4 carbon atoms, preferably methyl or ethyl, C n H 2n Is a linear alkyl group containing 2 to 10 carbon atoms, X - As the halogen anion, chloride or bromide is preferable.
3. A method for producing a molecular sieve of MWW structure according to claim 2, wherein the modulus (SiO 2 :Na 2 The molar ratio of O) is 2 to 4.
4. A method of preparing a MWW structure molecular sieve according to any one of claims 1 to 3, wherein the mixing comprises first dissolving a first structure directing agent in water to form a solution; adding an aluminum source under stirring, and stirring and mixing for 2-12 hours; adding a silicon source to form liquid sol, and stirring and mixing for 6-18 hours; and adding the second structure directing agent, and stirring and mixing uniformly.
5. The process for producing a molecular sieve of MWW structure according to claim 4, wherein the crystallization temperature is 140 to 190 ℃, preferably 165 to 175 ℃; the crystallization time is 20 to 120 hours, preferably 25 to 75 hours.
6. A MWW structured molecular sieve produced according to the method for producing a MWW structured molecular sieve according to any one of claims 1 to 5, which is a nano lamellar molecular sieve having a silica to alumina ratio of 20 to 100, preferably 25 to 50; the thickness of the flakes is 5 to 30 nanometers, preferably 10 to 20 nanometers.
7. A method of preparing a xylene isomerization catalyst, the method comprising the steps of:
(1) Mixing and crystallizing a silicon source, an aluminum source, a first structure directing agent SDA1, a second structure directing agent SDA2 and water to obtain an MWW structure molecular sieve, wherein the silicon source is sodium silicate; the aluminum source is one or more selected from aluminum sulfate, aluminum chloride and aluminum nitrate; the second structure directing agent SDA2 is cyclohexylimine; the first structure directing agent SDA1 is (R 1 ) 3 N + C n H 2n N + (R 2 ) 3 ·2X - Wherein R is 1 And R is 2 Are all alkyl groups of 1 to 4 carbon atoms, preferably methyl or ethyl, C n H 2n Is a linear alkyl group containing 2 to 10 carbon atoms, X - Is a halogen anion, preferably chloride or bromide;
(2) Ion exchange is carried out on the MWW structure molecular sieve prepared in the step (1) by using the aqueous solution of the first structure directing agent SDA1, deionized water is used for washing and drying after the ion exchange, and then the MWW structure molecular sieve is mixed with an alumina binder, molded and roasted to obtain a catalyst carrier;
(3) Carrying out hydrothermal treatment on the catalyst carrier prepared in the step (2) by using the aqueous solution of the second structure directing agent SDA2 as a steam source to obtain a catalyst carrier with optimized acid function distribution; and
(4) And (3) carrying out impregnation treatment on the catalyst with optimized acid function distribution prepared in the step (3) by using a solution containing noble metals, and activating and reducing to prepare the dimethylbenzene isomerization catalyst.
8. The method for preparing a xylene isomerization catalyst according to claim 7, wherein in step (1) said silicon source (per SiO 2 Meter), aluminum source (according to Al 2 O 3 Calculated by weight) and water are added according to the molar ratio of SiO 2 :Al 2 O 3 :H 2 O=1:0.01-0.05:20-50; the mole ratio of the usage amount of the first structure directing agent SDA1 is SDA1 to SiO 2 =0.02 to 0.22; the second structure directing agent SDA2 is used in the molar ratio of SDA2 to SiO 2 ＝0.02～0.12。
9. The method of preparing a xylene isomerization catalyst of claim 7 or 8 wherein the mixing in step (1) comprises first dissolving a first structure directing agent in water to form a solution; adding an aluminum source under stirring, and stirring and mixing for 2-12 hours; adding a silicon source to form liquid sol, and stirring and mixing for 6-18 hours; and adding the second structure directing agent, and stirring and mixing uniformly.
10. The process for preparing a xylene isomerization catalyst according to claim 9, wherein the crystallization in step (1) is at a temperature of 140 to 190 ℃, preferably 165 to 175 ℃; the crystallization time is 20 to 120 hours, preferably 25 to 75 hours.
11. The process for preparing a xylene isomerization catalyst according to claim 7, wherein the concentration of the aqueous solution of the first structure directing agent SDA1 in step (2) is 0.01 to 0.08mol/L, preferably 0.04 to 0.06mol/L; the liquid-solid ratio of the ion exchange is 5-30 mL/g molecular sieve, and the temperature of the ion exchange is 50-90 ℃; na of MWW-structured molecular sieve of the obtained catalyst carrier 2 The molar content of O in the fully component oxide is 0.01 to 2.0%, preferably 0.1 to 0.4%.
12. The method for preparing a xylene isomerization catalyst according to claim 7, wherein the drying in step (2) is carried out at 120 ℃ for 8 to 24 hours,the calcination is carried out at 540 ℃ for 2-24 hours, and the drying and calcination are carried out in static atmosphere or at a volume space velocity of 50-500 hours -1 Is performed in a dynamic atmosphere.
13. The process for preparing a xylene isomerization catalyst according to claim 7 wherein the concentration of the aqueous solution of the second structure directing agent SDA2 in step (3) is 0.01 to 0.08mol/L, preferably 0.04 to 0.06mol/L, the amount of solution is 5 to 30mL/g of catalyst support, the steam treatment temperature is 200 to 450 ℃, preferably 350 to 400 ℃ and the treatment time is 3 to 6 hours.
14. The process for preparing a xylene isomerization catalyst according to claim 7, wherein the noble metal in step (4) is platinum, palladium, rhodium or ruthenium, preferably platinum.
15. The method for producing a xylene isomerization catalyst according to any one of claims 1 to 14, wherein the MWW structure molecular sieve produced in step (1) is a nano flake-like molecular sieve having a silica-alumina ratio of 20 to 100, preferably 25 to 50; the thickness of the flakes is 5 to 30 nanometers, preferably 10 to 20 nanometers.
16. The method for producing a xylene isomerization catalyst according to claim 15, wherein the content of the MWW structure molecular sieve as an acid catalytically active component in the xylene isomerization catalyst is 5 to 70 mass%, preferably 10 to 50 mass%, of the total mass of the catalyst; the content of the noble metal is 0.01 to 0.5 mass% of the total mass of the catalyst, preferably 0.05 to 0.35 mass%; the rest components are alumina binder.
17. A xylene isomerization catalyst prepared according to the method of preparing a xylene isomerization catalyst of any one of claims 7 to 14.
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