CN117920338A - Composite molecular sieve, preparation method and application thereof, and method for preparing olefin from low byproduct methanol - Google Patents
Composite molecular sieve, preparation method and application thereof, and method for preparing olefin from low byproduct methanol Download PDFInfo
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- 239000002808 molecular sieve Substances 0.000 title claims abstract description 99
- 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 99
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 title claims abstract description 96
- 239000002131 composite material Substances 0.000 title claims abstract description 65
- 238000000034 method Methods 0.000 title claims abstract description 46
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 title claims abstract description 38
- 150000001336 alkenes Chemical class 0.000 title claims abstract description 36
- 239000006227 byproduct Substances 0.000 title claims abstract description 26
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- 239000003054 catalyst Substances 0.000 claims abstract description 54
- 238000006243 chemical reaction Methods 0.000 claims abstract description 34
- 229910004298 SiO 2 Inorganic materials 0.000 claims abstract description 24
- 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 12
- 229910052593 corundum Inorganic materials 0.000 claims abstract description 12
- 229910001845 yogo sapphire Inorganic materials 0.000 claims abstract description 12
- 229910052782 aluminium Inorganic materials 0.000 claims description 43
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 41
- 239000000047 product Substances 0.000 claims description 35
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 30
- 229910052710 silicon Inorganic materials 0.000 claims description 30
- 239000010703 silicon Substances 0.000 claims description 30
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims description 21
- 238000000926 separation method Methods 0.000 claims description 19
- 239000003795 chemical substances by application Substances 0.000 claims description 18
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 17
- 229910052698 phosphorus Inorganic materials 0.000 claims description 17
- 239000011574 phosphorus Substances 0.000 claims description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- 229910052799 carbon Inorganic materials 0.000 claims description 15
- 239000012265 solid product Substances 0.000 claims description 14
- 239000002002 slurry Substances 0.000 claims description 13
- 229940073455 tetraethylammonium hydroxide Drugs 0.000 claims description 13
- LRGJRHZIDJQFCL-UHFFFAOYSA-M tetraethylazanium;hydroxide Chemical compound [OH-].CC[N+](CC)(CC)CC LRGJRHZIDJQFCL-UHFFFAOYSA-M 0.000 claims description 13
- 230000001174 ascending effect Effects 0.000 claims description 10
- 238000004891 communication Methods 0.000 claims description 8
- UAOMVDZJSHZZME-UHFFFAOYSA-N diisopropylamine Chemical compound CC(C)NC(C)C UAOMVDZJSHZZME-UHFFFAOYSA-N 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 8
- 238000011069 regeneration method Methods 0.000 claims description 8
- 150000001335 aliphatic alkanes Chemical class 0.000 claims description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 6
- 230000007704 transition Effects 0.000 claims description 6
- 239000013078 crystal Substances 0.000 claims description 5
- 238000002425 crystallisation Methods 0.000 claims description 5
- 230000008025 crystallization Effects 0.000 claims description 5
- 230000008929 regeneration Effects 0.000 claims description 5
- 230000015572 biosynthetic process Effects 0.000 claims description 2
- 229940086542 triethylamine Drugs 0.000 claims description 2
- 239000007789 gas Substances 0.000 description 24
- 239000000203 mixture Substances 0.000 description 11
- 239000002245 particle Substances 0.000 description 10
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 8
- 239000002994 raw material Substances 0.000 description 8
- 238000001228 spectrum Methods 0.000 description 8
- 238000001694 spray drying Methods 0.000 description 8
- 229910052739 hydrogen Inorganic materials 0.000 description 7
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 description 6
- 239000008367 deionised water Substances 0.000 description 6
- 229910021641 deionized water Inorganic materials 0.000 description 6
- 229930195733 hydrocarbon Natural products 0.000 description 6
- 150000002430 hydrocarbons Chemical class 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 6
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 6
- 238000010008 shearing Methods 0.000 description 6
- 239000000725 suspension Substances 0.000 description 6
- 239000005995 Aluminium silicate Substances 0.000 description 5
- 235000012211 aluminium silicate Nutrition 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 239000012043 crude product Substances 0.000 description 5
- 238000001035 drying Methods 0.000 description 5
- 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 5
- 239000001301 oxygen Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 239000004215 Carbon black (E152) Substances 0.000 description 4
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 239000002253 acid Substances 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 4
- 239000000571 coke Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 230000008021 deposition Effects 0.000 description 4
- 239000001294 propane Substances 0.000 description 4
- 238000010517 secondary reaction Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 238000006276 transfer reaction Methods 0.000 description 4
- 241000276425 Xiphophorus maculatus Species 0.000 description 3
- -1 carbon olefins Chemical class 0.000 description 3
- 239000003245 coal Substances 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000011159 matrix material Substances 0.000 description 3
- 238000001878 scanning electron micrograph Methods 0.000 description 3
- 238000005728 strengthening Methods 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 2
- 239000005977 Ethylene Substances 0.000 description 2
- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 2
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 150000001993 dienes Chemical class 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 2
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 239000002028 Biomass Substances 0.000 description 1
- 240000008042 Zea mays Species 0.000 description 1
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 description 1
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000029936 alkylation Effects 0.000 description 1
- 238000005804 alkylation reaction Methods 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 235000005822 corn Nutrition 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000009849 deactivation Effects 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- GDVKFRBCXAPAQJ-UHFFFAOYSA-A dialuminum;hexamagnesium;carbonate;hexadecahydroxide Chemical compound [OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Al+3].[Al+3].[O-]C([O-])=O GDVKFRBCXAPAQJ-UHFFFAOYSA-A 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000000445 field-emission scanning electron microscopy Methods 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 229910001701 hydrotalcite Inorganic materials 0.000 description 1
- 229960001545 hydrotalcite Drugs 0.000 description 1
- 230000000415 inactivating effect Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000006317 isomerization reaction Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000006384 oligomerization reaction Methods 0.000 description 1
- 125000005575 polycyclic aromatic hydrocarbon group Chemical group 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000007363 ring formation reaction Methods 0.000 description 1
- 238000002336 sorption--desorption measurement Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000004876 x-ray fluorescence Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
- B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- B01J29/80—Mixtures of different zeolites
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C1/00—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon
- C07C1/20—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon starting from organic compounds containing only oxygen atoms as heteroatoms
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/82—Phosphates
- B01J29/84—Aluminophosphates containing other elements, e.g. metals, boron
- B01J29/85—Silicoaluminophosphates [SAPO compounds]
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2529/00—Catalysts comprising molecular sieves
- C07C2529/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites, pillared clays
- C07C2529/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- C07C2529/80—Mixtures of different zeolites
-
- 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
- Y02P30/00—Technologies relating to oil refining and petrochemical industry
- Y02P30/20—Technologies relating to oil refining and petrochemical industry using bio-feedstock
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to the field of catalysts, and discloses a SAPO-34/SAPO-18 composite molecular sieve, a preparation method and application thereof, and a method for preparing olefin from low-byproduct methanol. The composite molecular sieve comprises SAPO-34 and SAPO-18, and the SiO 2/Al2O3 molar ratio of the composite molecular sieve is less than 0.2. The catalyst is applied to the reaction of preparing olefin from methanol, effectively inhibits the generation of byproducts and obviously improves the selectivity of olefin.
Description
Technical Field
The invention relates to the field of catalysts, in particular to a SAPO-34/SAPO-18 composite molecular sieve, a preparation method and application thereof, and a method for preparing olefin from low-byproduct methanol.
Background
Methanol To Olefins (MTO) is one of the important C1 chemical reactions and is considered to be the most successful method for producing low carbon olefins using a non-petroleum route. The method takes coal, natural gas and renewable biomass with rich reserves as raw materials, takes methanol as an intermediate, and finally produces low-carbon olefins such as ethylene, propylene and the like, and the route greatly relieves the dependence on petroleum resources, so that the MTO reaction is widely paid attention to domestic and foreign scientists in the last decades. In addition, according to the endowment of resources in China, the coal reserves are rich, the traditional coal chemical industry capacity is excessive, and the MTO route has very wide development space and huge application prospect in China.
The reaction of MTO comprises the following steps: dehydrating methanol on an acidic molecular sieve catalyst to generate dimethyl ether; the equilibrium mixture composed of methanol, dimethyl ether and water is converted into light olefin; further, high-carbon alkene, alkane, arene, naphthene and the like are generated by the secondary reactions such as oligomerization, cyclization, alkylation, isomerization, hydrogen transfer and the like. The catalytic conversion of methanol to hydrocarbons by the process of the wave (wave of corn, liu, yang Yongrong, wang Jingdai. Reaction mechanism of methanol to olefins [ J ]. Chemical evolution, 2009;21 (9): 1757-1762.) and the like is divided into the following 5 steps: step 1, methanol, DME and water reach equilibrium rapidly; step 2 is that before methanol and DME are substantially produced as hydrocarbons, the fresh catalyst is typically subjected to a1 kinetic induction period; step 3, generating hydrocarbon chemicals such as ethylene, propylene and the like; step 4, further reacting the generated olefin product to generate hydrocarbon; step 5 is the deactivation of the catalyst by carbon deposition. Wherein the further reaction of the olefin product in step 4 is closely related to the acid strength of the catalyst, the acid center density, the ratio of strong acid to weak acid centers, the morphology, grain size, space velocity and other process conditions of the catalyst. Therefore, in order to achieve the enhancement of the selectivity of ethylene and propylene as target products, it is necessary to reduce the reactions of the 4 th and 5 th steps, and further develop a low-by-product MTO catalyst, reactor and process conditions.
At present, the method for improving the selectivity of diene is focused on the aspects of strengthening the conversion of methanol and heavy hydrocarbon, but has no good method in the aspects of strengthening diffusion, reducing hydrogen transfer reaction, reducing byproduct generation and the like from three aspects of a catalyst, a reaction process and a reactor.
Disclosure of Invention
The invention aims to solve the problems that byproducts are required to be further reduced and target product selectivity is required to be further improved in the reaction of preparing olefin from methanol in the prior art, and provides a SAPO-34/SAPO-18 composite molecular sieve, a preparation method and application thereof, and a method for preparing olefin from low-byproduct methanol. The catalyst is applied to the reaction of preparing olefin from methanol, effectively inhibits the generation of byproducts and obviously improves the selectivity of olefin.
In order to achieve the above purpose, according to one aspect of the present invention, there is provided a composite molecular sieve of SAPO-34/SAPO-18, wherein the composite molecular sieve contains SAPO-34 and SAPO-18, and the molar ratio of SiO 2/Al2O3 of the composite molecular sieve is less than 0.2.
The second aspect of the invention provides a method for preparing a SAPO-34/SAPO-18 composite molecular sieve, the method comprising the following steps:
(1) Pre-crystallizing a first silicon source, a first aluminum source, a first phosphorus source, a first template agent and water to obtain a solid product containing SAPO-18 structural units, wherein the first aluminum source: the molar ratio of the first silicon source is 1: (0.02-0.25), wherein the first aluminum source is calculated as Al 2O3 and the first silicon source is calculated as SiO 2;
(2) Mixing a second silicon source, a second aluminum source, a second phosphorus source, a second template agent and water to obtain an initial slurry of the SAPO-34 molecular sieve, wherein the second aluminum source is as follows: the molar ratio of the second silicon source is 1: (0.05-0.35), wherein the second aluminum source is calculated as Al 2O3 and the second silicon source is calculated as SiO 2;
(3) And (3) mixing the solid product containing the SAPO-18 structural unit obtained in the step (1) with the initial slurry of the SAPO-34 molecular sieve, and then crystallizing to obtain the SAPO-34/SAPO-18 composite molecular sieve.
The inventors found in the research process that MTO byproducts include alkane and coke, alkane such as ethane and propane is generated by hydrogen transfer reaction of olefin, and coke is generated by dehydrogenation reaction of naphthene to further generate polycyclic aromatic hydrocarbon, thereby generating coke, and inactivating the catalyst. These side reactions are all caused by secondary reactions, and it is critical to avoid secondary reactions such as hydrogen transfer, etc., to reduce by-products and to increase target products such as ethylene and propylene. The inventor controls the acid and pore canal structure of the SAPO-34/SAPO-18 composite molecular sieve by controlling the dosage of the silicon source, so that the composite molecular sieve is suitable for the reaction of preparing olefin from methanol. The SAPO-34/SAPO-18 composite molecular sieve prepared by the invention is applied to the reaction of preparing olefin from methanol, is beneficial to strengthening the diffusion of target products, and can reduce the probability of hydrogen transfer reaction between hydrocarbon molecules, thereby reducing byproducts and increasing low-carbon olefin.
In a third aspect, the invention provides a method for preparing olefin from low byproduct methanol, comprising the following steps: carrying out contact reaction on methanol and a catalyst;
The catalyst comprises the SAPO-34/SAPO-18 composite molecular sieve according to the first aspect or the SAPO-34/SAPO-18 composite molecular sieve prepared by the method according to the second aspect.
Through the technical scheme, the beneficial effects of the invention include:
The SAPO-34/SAPO-18 composite molecular sieve disclosed by the invention is applied to a reaction for preparing olefin from methanol, and has the following advantages: 1. the reaction temperature is low, and the energy consumption is low; 2. the byproducts such as alkane, coke and the like are low, and the resource utilization rate is high; 3. the diene selectivity is high.
Preferably, the reaction device for the reaction for preparing the olefin from the methanol comprises quick separation equipment, so that the target product and the catalyst can be quickly separated, and the probability of generating byproducts can be further reduced.
Drawings
FIG. 1 is an XRD pattern and SEM image of a solid product containing SAPO-18 structural units prepared in preparation example 1;
FIG. 2 is an XRD spectrum and SEM image of the SAPO-34/SAPO-18 composite molecular sieve prepared in example 1;
FIG. 3 is a schematic diagram of a reaction-regeneration apparatus comprising a rapid separation device according to the present invention;
FIG. 4 is a schematic view of a portion of a quick-disconnect apparatus according to the present invention;
FIG. 5 is an XRD spectrum and SEM image of the SAPO-34 molecular sieve prepared in comparative example 1.
Description of the reference numerals
In fig. 3, 1, raw materials; 2. a fluidized bed reactor; 3. a transition section; 4. an ascending pipe; 5. a quick-separating sleeve; 8. crude product gas; 9. a gas chamber; 10. a cyclone separator set; 11. a regenerator cyclone separator set; 12. a regenerator; 13. air/oxygen; 14. a settler; 18. regenerating the inclined tube; 19. a waiting inclined tube;
In fig. 4, up tube; 5. a quick-separating sleeve; 6. a quick-separating inlet; 7. a quick-separating outlet; 15. a reducing nozzle; 16. an outer cylinder; 17. an inner cylinder.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
In one aspect, the invention provides a SAPO-34/SAPO-18 composite molecular sieve, wherein the composite molecular sieve contains SAPO-34 and SAPO-18, and the SiO 2/Al2O3 molar ratio of the composite molecular sieve is less than 0.2.
According to the present invention, preferably, the SiO 2/Al2O3 molar ratio of the composite molecular sieve is 0.1 to 0.19. By adopting the preferred embodiment, the number of the active sites is uniformly distributed, the hydrogen transfer reaction can be reduced, and the generation of byproducts such as alkane and the like can be reduced.
The SiO 2/Al2O3 molar ratio of the composite molecular sieve is measured by an X-ray fluorescence analyzer.
According to the invention, preferably, the crystal morphology of the composite molecular sieve is plate-shaped structure, and the length is 0.3-2 microns, preferably 0.5-1.5 microns; a width of 0.3 to 2 microns, preferably 0.5 to 1.5 microns; the thickness is 20-300 nm, preferably 50-200 nm.
The composite molecular sieve of the invention has a plurality of holes inside, preferably, the composite molecular sieve has a mesoporous and macroporous structure. By adopting the preferred embodiment, the rapid diffusion of the product is facilitated, and the occurrence of secondary reaction is avoided.
According to the invention, the mesoporous and large Kong Zongkong volumes of the composite molecular sieve are preferably 0.05-0.3cm 3/g, preferably 0.08-0.2cm 3/g.
The mesoporous and large Kong Zongkong volumes of the composite molecular sieve are measured by a nitrogen adsorption and desorption method.
According to the present invention, preferably, the SAPO-34 is present in an amount of 70 to 85 wt%, preferably 75 to 82 wt%, based on the total weight of the composite molecular sieve; the SAPO-18 content is 15-30 wt.%, preferably 18-25 wt.%.
The content of each component in the composite molecular sieve is determined by an X-ray diffraction method.
The second aspect of the invention provides a method for preparing a SAPO-34/SAPO-18 composite molecular sieve, the method comprising the following steps:
(1) Pre-crystallizing a first silicon source, a first aluminum source, a first phosphorus source, a first template agent and water to obtain a solid product containing SAPO-18 structural units, wherein the first aluminum source: the molar ratio of the first silicon source is 1: (0.02-0.25), wherein the first aluminum source is calculated as Al 2O3 and the first silicon source is calculated as SiO 2;
(2) Mixing a second silicon source, a second aluminum source, a second phosphorus source, a second template agent and water to obtain an initial slurry of the SAPO-34 molecular sieve, wherein the second aluminum source is as follows: the molar ratio of the second silicon source is 1: (0.05-0.35), wherein the second aluminum source is calculated as Al 2O3 and the second silicon source is calculated as SiO 2;
(3) And (3) mixing the solid product containing the SAPO-18 structural unit obtained in the step (1) with the initial slurry of the SAPO-34 molecular sieve, and then crystallizing to obtain the SAPO-34/SAPO-18 composite molecular sieve.
According to the present invention, preferably, the first aluminum source: the molar ratio of the first silicon source is 1: (0.03-0.2), wherein the first aluminum source is calculated as Al 2O3 and the first silicon source is calculated as SiO 2.
According to the present invention, preferably, the first aluminum source: a first phosphorus source: a first template agent: the molar ratio of H 2 O is 1: (0.1-1): (1-8): (10-100), preferably 1: (0.4-0.8): (2-6): (30-80), wherein the first aluminum source is calculated as Al 2O3 and the first phosphorus source is calculated as P 2O5.
The conditions for the pre-crystallization are not particularly limited and may be carried out by referring to a method conventional in the art. Preferably, the pre-crystallization conditions include: the temperature is 130-190 ℃, preferably 150-180 ℃; the time is 5-24 hours, preferably 8-18 hours.
In the present invention, the type of the template agent is selected in a wide range, preferably, the first template agent and the second template agent are each independently selected from at least one of N, N-diisopropylamine, tetraethylammonium hydroxide and triethylamine, preferably tetraethylammonium hydroxide and/or N, N-diisopropylamine, more preferably tetraethylammonium hydroxide and N, N-diisopropylamine.
According to the present invention, preferably, the molar ratio of tetraethylammonium hydroxide to N, N-diisopropylamine is 1: (0.5-5), preferably 1: (1-3).
The selection range of the types of the first phosphorus source, the first silicon source, the first aluminum source, the second phosphorus source, the second silicon source and the second aluminum source is wider, and the conventional selection in the field can be adopted, so that the invention is not repeated here.
According to the present invention, preferably, the second aluminum source: the molar ratio of the second silicon source is 1: (0.1-0.3), wherein the second aluminum source is calculated as Al 2O3 and the second silicon source is calculated as SiO 2.
According to the present invention, preferably, the second aluminum source: a second phosphorus source: and (2) a second template agent: the molar ratio of H 2 O is 1: (0.3-1.5): (1-8): (20-100), preferably 1: (0.6-1.2): (3-6): (30-80), wherein the second aluminum source is calculated as Al 2O3 and the second phosphorus source is calculated as P 2O5.
According to the present invention, preferably, the crystallization conditions include: the temperature is 160-230 ℃, preferably 180-210 ℃; the time is 8-35 hours, preferably 10-30 hours.
According to the invention, preferably, the solid product containing SAPO-18 structural units is used in an amount such that the SAPO-34/SAPO-18 composite molecular sieve is prepared, and the SAPO-34 content is 70 to 85 wt%, preferably 75 to 82 wt%, based on the total weight of the composite molecular sieve; the SAPO-18 content is 15-30 wt.%, preferably 18-25 wt.%.
Preferably, the pre-crystallized product is dried to yield a solid product comprising SAPO-18 structural units. The drying conditions may be performed according to conventional conditions, and the present invention will not be described herein.
According to one embodiment of the invention, the pre-crystallized product is cooled to room temperature and then dried.
Preferably, the method further comprises: and filtering, washing and drying the crystallized product to obtain the SAPO-34/SAPO-18 composite molecular sieve.
The conditions of the filtration, washing and drying are not particularly limited, and can be carried out according to conventional technical means in the art, and the invention is not described herein.
According to one embodiment of the invention, the crystallized product is cooled to room temperature and then filtered.
In the present invention, the "first" and "second" do not limit each substance and operation, but only distinguish substances introduced in different steps from each other, and perform operations in different stages.
The third invention provides a method for preparing olefin by low byproduct methanol, which comprises the following steps: carrying out contact reaction on methanol and a catalyst;
The catalyst comprises the SAPO-34/SAPO-18 composite molecular sieve according to the first aspect or the SAPO-34/SAPO-18 composite molecular sieve prepared by the method according to the second aspect.
The method for preparing the catalyst is not particularly limited and may be carried out by referring to a method conventional in the art. Preferably, the invention adopts the following method, in particular: the SAPO-34/SAPO-18 composite molecular sieve, a matrix material, a binder and deionized water are mixed to obtain slurry, and 90% of particles in the slurry have a particle size of 0.5-3.5 microns. And then carrying out spray drying and roasting on the slurry to obtain the catalyst.
Preferably, the SAPO-34/SAPO-18 composite molecular sieve: base material: and (2) a binder: the weight ratio of deionized water is (5-50) to (10-30): (5-20): (20-80).
The selection of the type of the matrix material is wide, preferably the matrix material is clay and/or hydrotalcite, more preferably kaolin.
The selection range of the binder is wide, and the binder can be a conventional selection in the field, and the invention is not described herein.
Preferably, the conditions of spray drying and baking may be performed according to conventional conditions, and the present invention will not be described herein.
According to one embodiment of the invention, the molecular sieve is used for: kaolin: aluminum sol: deionized water = 12:18:10:60 weight percent of raw materials are weighed to prepare slurry with the solid content of 40 percent, and the raw materials are calculated on a dry basis except water. Adding kaolin into deionized water, and shearing at a high speed for 15 minutes; adding the SAPO-34/SAPO-18 composite molecular sieve, and shearing at a high speed for 15 minutes; finally, an aluminum sol was added and high-speed shearing was performed for 45 minutes to obtain a suspension for spray drying. The particle size of the particles in this suspension was measured by a laser particle sizer to be 2.5 microns. And (3) spray drying the suspension, controlling the outlet temperature of spray drying tail gas to be 150 ℃, and roasting the dried material at 550 ℃ for 5 hours after spraying is finished, so as to obtain the catalyst.
According to the invention, preferably the reaction conditions include: the reaction temperature is not higher than 450 ℃, preferably 420-440 ℃; the gas linear velocity is 0.2-3m/s, preferably 0.5-2.5m/s; the pressure is 0.05-0.3MPa, preferably 0.1-0.25MPa.
According to the present invention, it is preferable that the alkane generating amount is 1% by weight or less and the carbon content is 3.5% by weight or less based on the total weight of the product.
According to the present invention, preferably, the method is carried out in an apparatus for producing olefins from low by-product methanol, as shown in fig. 3, which comprises: a fluidized bed reactor 2, an up-pipe 4, a fast separating device, a settler 14, a cyclone set 10 and a regenerator 12, wherein the fast separating device comprises a fast separating sleeve 5, a fast separating inlet 6 and a fast separating outlet 7.
The reaction device for the reaction for preparing the olefin from the methanol comprises quick separation equipment, wherein the quick separation equipment is sleeve type quick separation equipment which is directly connected with a coupling stripper, and the mixed gas flowing in through an outer stripper has high-speed centrifugal entrainment effect, so that on one hand, the quick coarse separation of crude product gas at the outlet of the reactor and a catalyst is enhanced, and the probability of byproduct generation is further reduced. On the other hand, the partial pressure of the crude product gas in the product gas is diluted, so that side reactions are effectively restrained, and a synergistic effect is formed with low catalytic byproducts in the reactor, so that good byproduct reduction performance is achieved.
According to the invention, the fluidized-bed reactor 2 is preferably in communication with an ascending pipe 4 via a transition section 3.
According to the invention, the quick-release sleeve 5 is preferably in communication with the up-tube 4 and the quick-release outlet 7.
According to the invention, preferably, said quick-release inlet 6 communicates with the quick-release sleeve 5.
According to the invention, the cyclone separator group 10 is preferably in communication with the plenum 9, the interior space of the settler 14, respectively.
According to the invention, preferably, said rapid inlet 6 communicates with a stripper at the bottom of the settler 14.
According to the invention, the quick-break outlet 7 is preferably connected directly to the cyclone bank 10 without passing through the interior space of the settler 14.
According to the invention, the fluidized-bed reactor 2 is preferably in communication with the regenerator 12 via a regeneration chute 18, and the stripper is in communication with the regenerator via a spent chute 19.
According to the invention, the quick-release sleeve 5 preferably comprises an outer cylinder 16 and an inner cylinder 17, the inner cylinder 17 being a cylinder.
The cross section area of the inner cylinder and the cross section area of the ascending pipe can be the same or different, and the ascending pipe and the inner cylinder are preferably communicated in an integrated mode for economical efficiency and convenience.
According to the present invention, it is preferable that the ratio of the cross-sectional area of the inner cylinder 17 to the area of the lower bottom surface of the outer cylinder 16 is 0.5 to 0.95.
According to the present invention, it is preferable that the area ratio of the upper bottom surface to the lower bottom surface of the outer tub 16 is 0.2 to 0.8.
According to the present invention, it is preferable that the ratio of the upper bottom surface area of the outer cylinder 16 to the cross-sectional area of the inner cylinder 17 is 0.5 to 0.9.
According to the present invention, it is preferable that the ratio of the distance between the lower bottom surface of the outer tub 16 and the top of the inner tub 17 to the height of the outer tub is 0.001-0.01.
According to the present invention, preferably, the top of the inner cylinder 17 is provided with a reducing nozzle 15, and the ratio of the area of the upper bottom surface of the reducing nozzle 15 to the area of the cross section of the inner cylinder 17 is 0.2-0.7.
In the reactor according to the invention, the feedstock 1 enters the fluidized bed reactor 2 and is mixed with catalyst particles from the regeneration chute 18 and reacted to form olefin products, while forming spent catalyst. The mixture of spent catalyst and olefin products sequentially passes through the transition section 3 and the ascending pipe 4, enters the rapid separation device shown in fig. 4, flows out of the rapid separation outlet 7 after passing through the inner cylinder 17 of the sleeve 5 and exiting from the retracting nozzle 15, and in addition, the gas in the reactor enters the cavity between the inner cylinder 17 and the outer cylinder 16 of the sleeve 5 from the rapid separation inlet 6 and also flows out of the rapid separation outlet 7. The olefin product gas carries part of spent catalyst to be separated by a cyclone separator group 10, the separated product gas is led out from a gas chamber 9 to obtain crude product gas 8, and most of spent catalyst is settled in a settler 14 and enters a stripper. After the spent catalyst in the stripper is stripped, the spent catalyst is led out by a spent inclined tube 19 and enters a regenerator 12, oxygen or air 13 enters the regenerator 12 to contact with the spent catalyst, part of the regenerated catalyst carried by the air/oxygen is separated by a regenerator cyclone separator group 11, and the regenerated catalyst flows into a fluidized bed reactor 2 to continuously react with the raw material 1 in the reactor, so that the process circulation is completed.
According to the invention, the linear velocity of the gas in the inner cylinder 17 is preferably 2-10m/s, preferably 3-8m/s.
According to the invention, the gas line speed of the rapid-dividing inlet 6 is preferably 4-25m/s, preferably 6-20m/s.
The present invention will be described in detail by examples.
In the following examples, XRD patterns were measured by a Brookfield AXS D8 Advance X-ray diffractometer, germany.
SEM spectra were measured by FEI Quanta200F field emission scanning electron microscopy, netherlands.
N 2 adsorption-desorption data were measured by an America microphone ASAP-2020 adsorption instrument.
The reagents used in the following examples were commercially available and were analytically pure.
Preparation example 1
Preparation of solid products containing SAPO-18 building blocks
Silica sol (30 wt% SiO 2), pseudo-boehmite (70 wt% Al 2O3) and phosphoric acid (85 wt% H 3PO4) are respectively used as a silicon source, an aluminum source and a phosphorus source, and a mixture of tetraethylammonium hydroxide and N, N-diisopropylamine is used as a template agent according to SiO 2：Al2O3：P2O5: template agent: h 2 o=0.03: 1:0.8:3:50 to produce a mixture gel, wherein the molar ratio of tetraethylammonium hydroxide to N, N-diisopropylamine is 2:3. the mixture was gelled and crystallized at 150℃for 18 hours. And cooling the crystallized product, and then directly drying to obtain a solid product containing the SAPO-18 structural unit, wherein the obtained product is denoted as A.
XRD patterns and SEM pictures are shown in FIG. 1, and the results show that the synthesized molecular sieve has characteristic diffraction peaks of the SAPO-18 molecular sieve. SEM pictures show that the prepared SAPO-18 molecular sieve has flaky crystals with the grain size of 0.2-0.5 microns.
Preparation example 2
Preparation of solid products containing SAPO-18 building blocks
The procedure of preparation 1 was followed, except that the molar ratio of SiO 2：Al2O3 =0.2, and the molar ratio of tetraethylammonium hydroxide and N, N-diisopropylamine in the template was 1:1, the mixture gel was crystallized at 180℃for 8 hours. The resulting product was designated B.
B has XRD spectrum and SEM photograph similar to those of FIG. 1, showing that the synthesized molecular sieve has characteristic diffraction peaks of SAPO-18 molecular sieve. SEM pictures show that the prepared SAPO-18 molecular sieve has flaky crystals with the grain size of 0.2-0.5 microns.
Example 1
Silica sol (30 wt% SiO 2), pseudo-boehmite (70 wt% Al 2O3) phosphoric acid (85 wt%), triethylamine, and tetraethylammonium hydroxide, according to SiO 2：Al2O3：P2O5: template agent: h 2 o=0.3: 1:1.1:4:50 to obtain an initial slurry of the SAPO-34 molecular sieve, wherein triethylamine: tetraethylammonium hydroxide molar ratio = 2:1. then, component A containing the SAPO-18 molecular sieve structural unit prepared in preparation example 1 is added, and stirring is continued for more than 2 hours, so as to obtain a mixture. The mixture was crystallized at 180℃for 30 hours. And cooling, filtering, washing and drying the crystallized product to obtain the SAPO-34/SAPO-18 composite molecular sieve, which is marked as C.
The XRD spectrum and SEM photograph of the exemplary given C are shown in figure 2, and as can be seen from figure 2, the synthesized molecular sieve has characteristic diffraction peaks of the SAPO-34/SAPO-18 molecular sieve, which indicates that the synthesized product is the SAPO-34/SAPO-18 composite molecular sieve with platy structure morphology.
Example 2
The procedure of example 1 was followed, except that SiO 2：Al2O3 =0.2, component B containing SAPO-18 molecular sieve structural units prepared in preparation example 2 was added, and the mixture was crystallized at 210 ℃ for 10 hours, and the resulting product was designated as D.
The XRD spectrum and SEM photograph of D are similar to those of FIG. 2, and the synthesized molecular sieve is proved to have characteristic diffraction peaks of the SAPO-34/SAPO-18 molecular sieve, and the morphology of the composite molecular sieve is a SAPO-34/SAPO-18 composite molecular sieve with a platy structure.
Comparative example 1
The procedure of example 1 was followed, except that the solid product comprising SAPO-18 molecular sieve structural units prepared in preparation example 1 was not added during the molecular sieve synthesis, and the resulting product was designated as E.
The XRD spectrum and SEM of E are shown in figure 5, and the synthesized molecular sieve has characteristic diffraction peaks of the SAPO-34 molecular sieve; the crystal of the molecular sieve is cube, the grain size is 2-3 microns, the surface is smooth, and the mesoporous and macroporous structures are avoided. According to the XRD spectrogram and SEM photo results, the prepared molecular sieve is a square SAPO-34 molecular sieve.
Comparative example 2
The procedure of example 1 was followed, except that SiO 2：Al2O3 =0.5 was added to component a containing SAPO-18 molecular sieve structural units prepared in preparation example 1, and the resulting product was designated as F.
The XRD spectrum and SEM photograph of F are similar to those of FIG. 2, and the synthesized molecular sieve is proved to have characteristic diffraction peaks of the SAPO-34/SAPO-18 molecular sieve, and the morphology of the composite molecular sieve is a SAPO-34/SAPO-18 composite molecular sieve with a platy structure.
TABLE 1
Test example 1
Preparation of MTO catalyst: molecular sieve: kaolin: aluminum sol: deionized water = 12:18:10:60 weight percent of raw materials are weighed to prepare slurry with the solid content of 40 percent, and the raw materials are calculated on a dry basis except water. Adding kaolin into deionized water, and shearing at a high speed for 15 minutes; adding the SAPO-34/SAPO-18 composite molecular sieves prepared in the examples and the comparative examples respectively, and shearing at a high speed for 15 minutes; finally, an aluminum sol was added and high-speed shearing was performed for 45 minutes to obtain a suspension for spray drying. The particle size of the suspension particles was measured by a laser particle sizer to be 2.5 microns. And (3) spray drying the suspension, controlling the outlet temperature of spray drying tail gas to be 150 ℃, and roasting the dried material at 550 ℃ for 5 hours after spraying is finished, so as to obtain the catalyst.
The reaction-regeneration apparatus comprising the rapid separation device of the present invention shown in fig. 3 was used as an evaluation apparatus for the MTO catalyst prepared as described above, the regeneration medium was air, and the reaction conditions in the fluidized bed reactor were: the reaction pressure was 0.1MPa in terms of gauge pressure, the average temperature was 440 ℃, the gas linear velocity was 1.2m/s, and the results of the reaction are shown in Table 2. In the reaction, the low-carbon olefin yield, the ethane+propane selectivity and the carbon deposition amount of the catalyst refer to the low-carbon olefin yield, the ethane+propane selectivity and the carbon deposition amount of the catalyst when the low-carbon olefin yield is at the highest point in the reaction process.
In the reactor according to the invention, the feedstock 1 enters the fluidized bed reactor 2 and is mixed with catalyst particles from the regeneration chute 18 and reacted to form olefin products, while forming spent catalyst. The spent catalyst and olefin products sequentially pass through the transition section 3 and the ascending pipe 4 and enter the rapid separation device shown in fig. 4, the mixture of the spent catalyst and the olefin products sequentially passes through the transition section 3 and the ascending pipe 4 and enters the rapid separation device shown in fig. 4, the mixture of the spent catalyst and the olefin products flows out of the rapid separation outlet 7 after flowing out of the retracting nozzle 15 through the inner cylinder 17 of the sleeve 5, and in addition, the gas in the reactor enters a cavity between the inner cylinder 17 and the outer cylinder 16 of the sleeve 5 from the rapid separation inlet 6 and also flows out of the rapid separation outlet 7. The olefin product gas carries part of spent catalyst to be separated by a cyclone separator group 10, the separated product gas is led out from a gas chamber 9 to obtain crude product gas 8, and most of spent catalyst is settled in a settler 14 and enters a stripper. After the spent catalyst in the stripper is stripped, the spent catalyst is led out by a spent inclined tube 19 and enters a regenerator 12, oxygen or air 13 enters the regenerator 12 to contact with the spent catalyst, part of the regenerated catalyst carried by the air/oxygen is separated by a regenerator cyclone separator group 11, and the regenerated catalyst flows into a fluidized bed reactor 2 to continuously react with the raw material 1 in the reactor, so that the process circulation is completed.
The quick-separating device (see fig. 4) comprises a quick-separating sleeve 5, a quick-separating inlet 6 and a quick-separating outlet 7, wherein the quick-separating sleeve 5 comprises an outer cylinder 16 and an inner cylinder 17, and the inner cylinder 17 is a cylinder. The ratio of the cross-sectional area of the inner cylinder 17 to the area of the lower bottom surface of the outer cylinder 16 is 0.8; the area ratio of the upper bottom surface to the lower bottom surface of the outer cylinder 16 is 0.5; the ratio of the upper bottom surface area of the outer cylinder 16 to the cross-sectional area of the inner cylinder 17 is 0.7; the ratio of the distance between the lower bottom surface of the outer cylinder 16 and the top of the inner cylinder 17 to the height of the outer cylinder is 0.004; the top of the inner cylinder 17 is provided with a reducing nozzle 15, and the ratio of the area of the upper bottom surface of the reducing nozzle 15 to the area of the cross section of the inner cylinder 17 is 0.45. The gas linear velocity in the inner cylinder 17 is 4.6m/s, and the gas linear velocity in the quick-dividing inlet 6 is 13.5m/s.
TABLE 2
Test example 2
The conventional reaction-regeneration apparatus without rapid separation equipment was used as an evaluation apparatus for MTO catalyst under the same evaluation conditions as those of test example 1, and the catalyst was a composite molecular sieve comprising SAPO-34/SAPO-18 prepared in example 1. The reaction product was analyzed by gas chromatography, the yield of the low-carbon olefin at the outlet of the reactor was 83.18wt%, the selectivity of ethane+propane was 1.2wt%, and the carbon deposition amount of the catalyst was 3.8 wt%.
As can be seen from the results of the test examples, the MTO catalyst comprising the composite SAPO-34/SAPO-18 molecular sieve of the invention is applied to the reaction of preparing olefin from methanol, and has significantly lower byproduct selectivity and higher product yield. Preferably, the reaction device comprising the rapid separation equipment is used in industrial production of methanol to olefin, further reduces byproducts and remarkably improves target products such as low-carbon olefin and the like, and has great technical advantages.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (12)
1. The SAPO-34/SAPO-18 composite molecular sieve is characterized in that the composite molecular sieve contains SAPO-34 and SAPO-18, and the SiO 2/Al2O3 molar ratio of the composite molecular sieve is less than 0.2.
2. The composite molecular sieve of claim 1, wherein,
The SiO 2/Al2O3 molar ratio of the composite molecular sieve is 0.1-0.19;
Preferably, the crystal morphology of the composite molecular sieve is plate-shaped structure, and the length is 0.3-2 microns, preferably 0.5-1.5 microns; a width of 0.3 to 2 microns, preferably 0.5 to 1.5 microns; the thickness is 20-300 nm, preferably 50-200 nm;
Preferably, the composite molecular sieve has a mesoporous and macroporous structure;
Preferably, the mesoporous and large Kong Zongkong volumes of the composite molecular sieve are 0.05-0.3cm 3/g, preferably 0.08-0.2cm 3/g;
preferably, the SAPO-34 is present in an amount of 70 to 85 wt%, preferably 75 to 82 wt%, based on the total weight of the composite molecular sieve; the SAPO-18 content is 15-30 wt.%, preferably 18-25 wt.%.
3. A preparation method of a SAPO-34/SAPO-18 composite molecular sieve, the method comprises the following steps:
(1) Pre-crystallizing a first silicon source, a first aluminum source, a first phosphorus source, a first template agent and water to obtain a solid product containing SAPO-18 structural units, wherein the first aluminum source: the molar ratio of the first silicon source is 1: (0.02-0.25), wherein the first aluminum source is calculated as Al 2O3 and the first silicon source is calculated as SiO 2;
(2) Mixing a second silicon source, a second aluminum source, a second phosphorus source, a second template agent and water to obtain an initial slurry of the SAPO-34 molecular sieve, wherein the second aluminum source is as follows: the molar ratio of the second silicon source is 1: (0.05-0.35), wherein the second aluminum source is calculated as Al 2O3 and the second silicon source is calculated as SiO 2;
(3) And (3) mixing the solid product containing the SAPO-18 structural unit obtained in the step (1) with the initial slurry of the SAPO-34 molecular sieve, and then crystallizing to obtain the SAPO-34/SAPO-18 composite molecular sieve.
4. The method of claim 3, wherein,
A first aluminum source: the molar ratio of the first silicon source is 1: (0.03-0.2), wherein the first aluminum source is calculated as Al 2O3 and the first silicon source is calculated as SiO 2;
Preferably, the first aluminum source: a first phosphorus source: a first template agent: the molar ratio of H 2 O is 1: (0.1-1): (1-8): (10-100), preferably 1: (0.4-0.8): (2-6): (30-80), wherein the first aluminum source is calculated as Al 2O3 and the first phosphorus source is calculated as P 2O5;
Preferably, the pre-crystallization conditions include: the temperature is 130-190 ℃, preferably 150-180 ℃; the time is 5-24 hours, preferably 8-18 hours;
Preferably, the first template agent and the second template agent are each independently selected from at least one of N, N-diisopropylamine, tetraethylammonium hydroxide and triethylamine, preferably tetraethylammonium hydroxide and/or triethylamine, more preferably tetraethylammonium hydroxide and triethylamine;
preferably, the molar ratio of tetraethylammonium hydroxide to triethylamine is 1: (0.5-5), preferably 1: (1-3).
5. The method according to claim 3 or 4, wherein,
A second aluminum source: the molar ratio of the second silicon source is 1: (0.1-0.3), wherein the second aluminum source is calculated as Al 2O3 and the second silicon source is calculated as SiO 2;
preferably, the second aluminum source: a second phosphorus source: and (2) a second template agent: the molar ratio of H 2 O is 1: (0.3-1.5): (1-8): (20-100), preferably 1: (0.6-1.2): (3-6): (30-80), wherein the second aluminum source is calculated as Al 2O3 and the second phosphorus source is calculated as P 2O5;
Preferably, the crystallization conditions include: the temperature is 160-230 ℃, preferably 180-210 ℃; the time is 8-35 hours, preferably 10-30 hours.
6. The method according to any one of claims 3-5, wherein,
The solid product containing the SAPO-18 structural units and the initial slurry of the SAPO-34 molecular sieve are used in an amount such that the content of the SAPO-34 in the prepared SAPO-34/SAPO-18 composite molecular sieve is 70 to 85 weight percent, preferably 75 to 82 weight percent, based on the total weight of the composite molecular sieve; the SAPO-18 content is 15-30 wt.%, preferably 18-25 wt.%.
7. A method for preparing olefin by low byproduct methanol, comprising the following steps: carrying out contact reaction on methanol and a catalyst;
the catalyst comprises the SAPO-34/SAPO-18 composite molecular sieve according to any one of 1-2 or the SAPO-34/SAPO-18 composite molecular sieve prepared by the method according to any one of 3-6.
8. The method of claim 7, wherein,
The reaction conditions include: the reaction temperature is not higher than 450 ℃, preferably 420-440 ℃; the gas linear velocity is 0.2-3m/s, preferably 0.5-2.5m/s; the pressure is 0.05-0.3MPa, preferably 0.1-0.25MPa;
Preferably, the alkane formation is less than 1% by weight and the carbon content is less than 3.5% by weight, based on the total weight of the product.
9. The process of claim 7, wherein the process is carried out in a low byproduct methanol to olefins plant comprising: fluidized bed reactor (2), ascending pipe (4), quick-separating equipment, settler (14), cyclone separator group (10) and regenerator (12), wherein, quick-separating equipment includes quick-separating sleeve (5), quick-separating entry (6) and quick-separating outlet (7).
10. The method of claim 9, wherein,
The fluidized bed reactor (2) is communicated with an ascending pipe (4) through a transition section (3);
Preferably, the quick-separating sleeve (5) is communicated with the ascending pipe (4) and the quick-separating outlet (7);
preferably, the quick-separating inlet (6) is communicated with the quick-separating sleeve (5);
Preferably, the cyclone separator group (10) is respectively communicated with the air chamber (9) and the inner space of the settler (14);
preferably, the rapid inlet (6) is in communication with a stripper at the bottom of the settler (14);
preferably, the quick-separating outlet (7) is directly connected with the cyclone separator group (10) without passing through the inner space of the settler (14);
preferably, the fluidized bed reactor (2) is in communication with the regenerator (12) via a regeneration chute (18) and the stripper is in communication with the regenerator via a spent chute (19).
11. The method of claim 9, wherein,
The quick-separating sleeve (5) comprises an outer cylinder (16) and an inner cylinder (17), and the inner cylinder (17) is a cylinder;
Preferably, the ratio of the cross-sectional area of the inner cylinder (17) to the lower bottom surface area of the outer cylinder (16) is 0.5-0.95;
preferably, the area ratio of the upper bottom surface to the lower bottom surface of the outer cylinder (16) is 0.2-0.8;
preferably, the ratio of the upper bottom surface area of the outer cylinder (16) to the cross-sectional area of the inner cylinder (17) is 0.5-0.9;
Preferably, the ratio of the distance between the lower bottom surface of the outer cylinder (16) and the top of the inner cylinder (17) to the height of the outer cylinder is 0.001-0.01;
Preferably, the top of the inner cylinder (17) is provided with a reducing nozzle (15), and the ratio of the area of the upper bottom surface of the reducing nozzle (15) to the area of the cross section of the inner cylinder (17) is 0.2-0.7.
12. The method according to any one of claims 9-11, wherein,
The linear velocity of the gas in the inner cylinder (17) is 2-10m/s, preferably 3-8m/s;
the gas linear velocity of the rapid separation inlet (6) is 4-25m/s, preferably 6-20m/s.
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