CN115703641A - Preparation method and application of Zn-MFI molecular sieve - Google Patents
Preparation method and application of Zn-MFI molecular sieve Download PDFInfo
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- 239000002808 molecular sieve Substances 0.000 title claims abstract description 49
- 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 49
- 238000002360 preparation method Methods 0.000 title claims abstract description 31
- 239000011701 zinc Substances 0.000 claims abstract description 61
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 33
- 229910004298 SiO 2 Inorganic materials 0.000 claims abstract description 25
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-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
- WHMDKBIGKVEYHS-IYEMJOQQSA-L Zinc gluconate Chemical compound [Zn+2].OC[C@@H](O)[C@@H](O)[C@H](O)[C@@H](O)C([O-])=O.OC[C@@H](O)[C@@H](O)[C@H](O)[C@@H](O)C([O-])=O WHMDKBIGKVEYHS-IYEMJOQQSA-L 0.000 claims abstract description 22
- 239000011670 zinc gluconate Substances 0.000 claims abstract description 22
- 229960000306 zinc gluconate Drugs 0.000 claims abstract description 22
- 235000011478 zinc gluconate Nutrition 0.000 claims abstract description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 21
- 230000032683 aging Effects 0.000 claims abstract description 12
- 238000002156 mixing Methods 0.000 claims abstract description 9
- 239000000463 material Substances 0.000 claims abstract description 8
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 112
- 239000003054 catalyst Substances 0.000 claims description 65
- 238000006243 chemical reaction Methods 0.000 claims description 65
- 239000001294 propane Substances 0.000 claims description 56
- 238000006356 dehydrogenation reaction Methods 0.000 claims description 32
- 238000000034 method Methods 0.000 claims description 28
- 238000003756 stirring Methods 0.000 claims description 20
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 17
- 239000007787 solid Substances 0.000 claims description 17
- 238000001035 drying Methods 0.000 claims description 13
- 229910052799 carbon Inorganic materials 0.000 claims description 12
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 claims description 10
- VDZOOKBUILJEDG-UHFFFAOYSA-M tetrabutylammonium hydroxide Chemical compound [OH-].CCCC[N+](CCCC)(CCCC)CCCC VDZOOKBUILJEDG-UHFFFAOYSA-M 0.000 claims description 10
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims description 8
- 238000005216 hydrothermal crystallization Methods 0.000 claims description 8
- LPSKDVINWQNWFE-UHFFFAOYSA-M tetrapropylazanium;hydroxide Chemical compound [OH-].CCC[N+](CCC)(CCC)CCC LPSKDVINWQNWFE-UHFFFAOYSA-M 0.000 claims description 8
- JRMUNVKIHCOMHV-UHFFFAOYSA-M tetrabutylammonium bromide Chemical compound [Br-].CCCC[N+](CCCC)(CCCC)CCCC JRMUNVKIHCOMHV-UHFFFAOYSA-M 0.000 claims description 4
- BGQMOFGZRJUORO-UHFFFAOYSA-M tetrapropylammonium bromide Chemical compound [Br-].CCC[N+](CCC)(CCC)CCC BGQMOFGZRJUORO-UHFFFAOYSA-M 0.000 claims description 4
- 230000009471 action Effects 0.000 claims description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims 1
- 230000003197 catalytic effect Effects 0.000 abstract description 6
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 27
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 27
- 230000015572 biosynthetic process Effects 0.000 description 18
- 238000003786 synthesis reaction Methods 0.000 description 18
- 238000002425 crystallisation Methods 0.000 description 15
- 230000008025 crystallization Effects 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 10
- 230000008569 process Effects 0.000 description 10
- 239000002994 raw material Substances 0.000 description 9
- 239000008367 deionised water Substances 0.000 description 8
- 229910021641 deionized water Inorganic materials 0.000 description 8
- 238000005406 washing Methods 0.000 description 8
- 238000002441 X-ray diffraction Methods 0.000 description 7
- 229910052725 zinc Inorganic materials 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 6
- 239000000843 powder Substances 0.000 description 6
- 239000012265 solid product Substances 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 239000013078 crystal Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 229910021485 fumed silica Inorganic materials 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 4
- 150000001336 alkenes Chemical class 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 238000001027 hydrothermal synthesis Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- ONDPHDOFVYQSGI-UHFFFAOYSA-N zinc nitrate Chemical compound [Zn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ONDPHDOFVYQSGI-UHFFFAOYSA-N 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 229910002846 Pt–Sn Inorganic materials 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
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- 229910000510 noble metal Inorganic materials 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 229910001220 stainless steel Inorganic materials 0.000 description 3
- 239000010935 stainless steel Substances 0.000 description 3
- 238000005303 weighing Methods 0.000 description 3
- LDXJRKWFNNFDSA-UHFFFAOYSA-N 2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-1-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]ethanone Chemical compound C1CN(CC2=NNN=C21)CC(=O)N3CCN(CC3)C4=CN=C(N=C4)NCC5=CC(=CC=C5)OC(F)(F)F LDXJRKWFNNFDSA-UHFFFAOYSA-N 0.000 description 2
- ZOIORXHNWRGPMV-UHFFFAOYSA-N acetic acid;zinc Chemical compound [Zn].CC(O)=O.CC(O)=O ZOIORXHNWRGPMV-UHFFFAOYSA-N 0.000 description 2
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- 239000004246 zinc acetate Substances 0.000 description 2
- YLZOPXRUQYQQID-UHFFFAOYSA-N 3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-1-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]propan-1-one Chemical compound N1N=NC=2CN(CCC=21)CCC(=O)N1CCN(CC1)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F YLZOPXRUQYQQID-UHFFFAOYSA-N 0.000 description 1
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- 229910007570 Zn-Al Inorganic materials 0.000 description 1
- 150000001335 aliphatic alkanes Chemical class 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
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- 229910052748 manganese Inorganic materials 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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Abstract
The application discloses a preparation method and application of a Zn-MFI molecular sieve. The preparation method comprises the following steps: a) Mixing materials containing a silicon source, an organic template agent R and water to obtain primary sol; in terms of mole ratios, the primary sol satisfies: r: siO 2 2 ＝0.3～15：1；H 2 O：SiO 2 =20 to 1000:1; wherein the mole number of the template agent R is calculated by the total mole number of the template agent contained in the template agent R; the silicon source is prepared by the mole number of the silicon sourceSiO 2 Calculating the mole number of the solution; the number of moles of water is calculated as its own number of moles; b) Adding a Zn source into the primary sol, and aging to obtain a final sol; the Zn source comprises zinc gluconate; c) And crystallizing the final sol, and removing the template agent to obtain the Zn-MFI molecular sieve. The preparation method uses zinc gluconate as a Zn source to synthesize the Zn-MFI molecular sieve, and has excellent catalytic performance.
Description
Technical Field
The application relates to a preparation method and application of a Zn-MFI molecular sieve.
Background
Light olefins are very important raw materials in the field of petrochemical industry nowadays, for example, ethylene and propylene are important raw materials for synthesizing plastics, fibers and various chemical materials, and the demand of light olefins is increasing day by day. However, the traditional process for producing low-carbon olefins cannot meet the propylene demand of the current market. Meanwhile, global petroleum resources are becoming scarce, and various petrochemical companies in the world actively develop alternative petroleum energy sources, such as: various production new routes such as preparation of low-carbon olefin from synthesis gas, preparation of Propylene (PDH) from propane dehydrogenation and the like; based on the resource characteristics of oil shortage, gas shortage and coal enrichment in China, the technology (DMTO-III) for preparing low-carbon olefin from methanol, which is developed by the institute of chemical and physical research, not only has the advantages of high conversion rate, high low-carbon olefin yield and the like, but also has very high strategic significance. In recent years, the maturity of the shale gas development technology in the united states keeps the market price of propane relatively low, so that the PDH process is rapidly developed, the selectivity of the target product propylene of the process is high and can reach more than 90% compared with other production processes, and the separation process of raw materials and products in the PDH process reaction is simple and the operation cost is low. The PDH process mainly has CB&Catofin technology of ILummus corporation, cr/Al is adopted 2 O 3 Catalyst, oleflex process from UOP company, using Pt-Sn/Al 2 O 3 Catalyst, STAR technology of Uhde company adopts Pt-Sn to load Zn-Al 2 O 3 Catalyst and PDH process from Linde-BASF using Pt-Sn/ZrO 2 A catalyst. It is well known that the noble metal Pt is expensive, while the metal Cr (VI) can cause various body diseases. Therefore, the development of economic and environment-friendly propane dehydrogenation catalysts has important research significance.
At present, the research of a comparative system has been carried out at home and abroad, in particular to the traditional Al taking a molecular sieve as a carrier 2 O 3 Is a carrier, and further improves the performance of the catalyst. CN201410483277.4 relates to MFI bi-component hetero prepared by hydrothermal synthesisThe atomic molecular sieve takes noble metal Pt as a main active point, sn element and any one element of Fe, zn, ni, co and Mn as a double heteroatom component, and when the catalyst is used for propane removal reaction, the propane conversion rate is 35 percent, the propylene selectivity is 98 percent at the highest, but the problems of high content (0.15-0.4 percent) of noble metal Pt, complex preparation process and high catalyst cost still exist. CN201910055367.6 relates to a catalyst prepared by a hydrothermal synthesis method or an impregnation method by using one of a ZSM-5 molecular sieve, a Y molecular sieve, an MCM-22 molecular sieve and a Beta molecular sieve as a carrier and precursors of metal elements Sn, ga, fe, co, ni and Zn. However, al contained in the carrier can generate B acid effect in the catalytic process, and side reactions such as alkane cracking, aromatization and the like are brought in the reaction of preparing propylene by propane dehydrogenation, so that the selectivity of the target product propylene is reduced.
Zn element is environment-friendly and isolated Zn 2+ The ionic state may be an active component of the propane dehydrogenation catalyst, and when present in the ZnO state, there is no propane dehydrogenation activity. In situ isolation of Zn 2+ Ion synthesis into molecular sieve frameworks is very challenging because metal salts have low solubility and tend to agglomerate easily under strongly basic conditions.
Disclosure of Invention
According to one aspect of the present application, there is provided a preparation method of a Zn-MFI molecular sieve, which synthesizes the Zn-MFI molecular sieve using inexpensive and environmentally friendly zinc gluconate as a Zn source, having excellent catalytic performance.
Zn incorporation by Zinc gluconate 2+ The ions are synthesized into an MFI-type framework and exist in isolated form. Meanwhile, zn-MFI has no Al element, only shows the L acid effect, so that propane dehydrogenation has better dehydrogenation activity and stability, and the preparation method is simple, has lower cost and has good industrial application prospect.
A preparation method of a Zn-MFI molecular sieve, which comprises the following steps:
a) Mixing materials containing a silicon source, an organic template agent R and water to obtain primary sol;
in terms of mole ratios, the primary sol satisfies:
R：SiO 2 ＝0.3～15：1；
H 2 O：SiO 2 ＝20～1000：1；
wherein the mole number of the template agent R is calculated by the total mole number of the template agent contained in the template agent R;
the mole number of the silicon source is SiO contained in the silicon source 2 Calculating the mole number of the solution;
the number of moles of water is calculated as its own number of moles;
b) Adding a Zn source into the primary sol, and aging to obtain a final sol;
the Zn source comprises zinc gluconate;
c) And carrying out hydrothermal crystallization on the final sol, and removing the template agent to obtain the Zn-MFI molecular sieve.
Optionally, in the step b), the addition amount of the Zn source is 1-10 wt% of the silicon source;
wherein the mass of the Zn source is calculated by the mass of Zn element;
the mass of the silicon source is SiO contained in the silicon source 2 And (4) calculating the mass.
Optionally, in step b), the amount of the Zn source added is 1 to 5wt% of the silicon source.
Optionally, in step b), the Zn source is added in an amount of 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt% of the silicon source; the lower limit is 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, or 9wt% of the silicon source.
Optionally, in step b), the aging conditions include:
the aging time is 3-24 h.
Optionally, the aging time is 3 to 6 hours.
Optionally, the upper aging time limit is selected from 4h, 5h, 6h, 8h, 10h, 15h, 18h, 22h or 25h, and the lower limit is selected from 3h, 4h, 5h, 6h, 8h, 10h, 15h, 18h or 22h.
Optionally, in step a), the silicon source includes at least one of tetraethoxysilane and silica sol;
the organic template agent R comprises at least one of tetrapropyl ammonium hydroxide, tetrabutyl ammonium hydroxide, tetrapropyl ammonium bromide and tetrabutyl ammonium bromide.
Optionally, in step a), the mixing is stirring mixing, and the stirring conditions include:
the stirring temperature is 50-80 ℃, and the stirring time is 2-6 h.
Optionally, in step c), the hydrothermal crystallization conditions include:
the hydrothermal crystallization temperature is 150-200 ℃, and the hydrothermal crystallization time is 60-120 h.
Optionally, the crystallization temperature has an upper limit selected from 160 ℃, 170 ℃, 180 ℃ or 200 ℃ and a lower limit selected from 150 ℃, 160 ℃, 170 ℃ or 180 ℃.
Optionally, the upper limit of the crystallization time is selected from 80h, 90h, 100h or 120h, and the lower limit is selected from 60h, 80h, 90h or 100h.
The template agent is removed by roasting, and the roasting conditions comprise:
the roasting temperature is 500-600 ℃, and the roasting time is 4-12 h.
Optionally, in step c), the method further comprises the following steps before removing the template agent:
separating and drying the solid in the crystallized product;
the drying conditions include:
the drying temperature is 80-120 ℃, and the drying time is 5-10 h.
Optionally, the size of the Zn-MFI molecular sieve is 200-300 nm
According to another method of the present application, there is provided a method for producing lower olefins by propane dehydrogenation, the method comprising the steps of:
reacting raw material gas containing propane under the action of a catalyst to obtain the low-carbon olefin;
the catalyst comprises the Zn-MFI molecular sieve prepared by the preparation method of any one of the above.
Optionally, the conditions of the reaction include:
the reaction temperature is 500-650 ℃, and the gas quality of the raw material isThe volume space velocity is 0.6 to 2.4h -1 。
Optionally, propane and a balance gas are included in the feed gas;
the volume ratio of the propane to the balance gas is 5-20.
Optionally, the volume ratio of propane to balance gas is 5 to 15.
Optionally, the volume ratio of propane to balance gas is 5 to 10.
The invention discloses a preparation method and application of a catalyst for preparing propylene by propane dehydrogenation, and particularly relates to a method for synthesizing a Zn-MFI molecular sieve by using cheap and environment-friendly zinc gluconate as a Zn source and application thereof. The catalyst synthesized by the invention shows good catalytic activity when being applied to a reaction process for preparing low-carbon olefin by propane dehydrogenation.
A method for preparing a catalyst for preparing propylene by propane dehydrogenation, comprising the following steps:
a) Uniformly mixing and stirring materials containing a silicon source, an organic template agent R and water at the temperature of 50-80 ℃, and stirring for 2-6 h to obtain transparent primary sol, wherein the molar ratio of the materials is as follows:
R：SiO 2 ＝0.3-15：1；
H 2 O：SiO 2 ＝20-1000：1；
b) Adding a Zn source to the primary sol; aging and stirring the mixture to synthesize a solution for 3 to 24 hours to obtain a final sol;
c) Putting the final sol into a reaction kettle, and crystallizing for 60-120 h at 150-200 ℃ to complete the crystallization reaction of the mixed sol;
d) Washing the solid crystal generated by crystallization with deionized water, and separating to obtain a solid;
f) Drying the obtained solid at 120 ℃ for 5-10 h to obtain Zn-MFI solid;
e) Grinding the solid into powder, roasting at 550 ℃ for 4-12 h, and removing the organic template machine to obtain Zn-MFI molecular sieve raw powder.
Optionally in step b), the Zn source is added in an amount of SiO 2 1 percent of the total mass～10％。
Optionally, the organic template R in step a) is selected from at least one of tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapropylammonium bromide and tetrabutylammonium bromide; the silicon source is at least one of tetraethoxysilane and silica sol.
Optionally, the source of Zn in step b) is zinc gluconate.
As an embodiment, the present application discloses the use of the catalyst prepared by the preparation method described in any one of the above in the preparation of lower olefins by propane dehydrogenation.
Optionally, raw material gas containing propane is introduced into a reactor filled with the catalyst to react under certain conditions, wherein the reaction temperature is 500-650 ℃, and the mass space velocity is 0.6-2.4 h -1 。
The application provides a catalyst, and the catalyst provided by the application is cheap and environment-friendly in raw materials. The catalyst is applied to the reaction of preparing low-carbon olefin by propane dehydrogenation, and shows higher propane conversion rate and propylene selectivity.
The beneficial effects that this application can produce include:
1) According to the preparation method of the Zn-MFI molecular sieve, the Zn-MFI molecular sieve is synthesized by using cheap and environment-friendly zinc gluconate as a Zn source, and has excellent catalytic performance.
2) According to the preparation method of the Zn-MFI molecular sieve, an aluminum source is not added, and precious metal elements are not used. The catalyst synthesized with isolated Zn 2+ Ions are active sites, no ZnO particles are generated, zn-MFI only shows L acid effect, and no other side reaction occurs in the propane dehydrogenation reaction.
3) The catalyst containing the Zn-MFI molecular sieve provided by the application shows higher propane conversion rate and propylene selectivity in the reaction of preparing low-carbon olefin by propane dehydrogenation.
Drawings
FIG. 1 is an SEM image of a Zn-MFI molecular sieve prepared in example 1 of the present application.
FIG. 2 is an XRD pattern of Zn-MFI molecular sieves prepared in examples 1 to 5 herein.
FIG. 3 is a graph showing propane dehydrogenation performance evaluation of the Zn-MFI molecular sieve of the present application at 550 ℃ with different Zn loadings.
FIG. 4 shows the evaluation of propane dehydrogenation performance of Zn-MFI molecular sieves prepared in example 2 of the present application at different reaction temperatures.
Detailed Description
The present application will be described in detail with reference to examples, but the present application is not limited to these examples.
The raw materials in the examples of the present application were all purchased commercially, unless otherwise specified.
As an embodiment, the present application discloses a method of preparing a catalyst, the method comprising:
a) Uniformly mixing and stirring materials containing a silicon source, an organic template agent R and water at the temperature of 50-80 ℃, and stirring for 2-6 h to obtain transparent primary sol, wherein the molar ratio of the materials is as follows:
R：SiO 2 ＝0.3-15：1；
H 2 O：SiO 2 ＝20-1000：1；
b) Adding a Zn source to the primary sol; aging and stirring the mixture to synthesize a solution for 3 to 24 hours to obtain a final sol;
c) Putting the final sol into a reaction kettle, and crystallizing for 60-120 h at 150-200 ℃ to complete the crystallization reaction of the mixed sol;
d) Washing the solid crystal generated by crystallization with deionized water, and separating to obtain a solid;
e) Drying the obtained solid at 120 ℃ for 5-10 h to obtain Zn-MFI solid;
f) Grinding the solid into powder, roasting at 550 ℃ for 4-12 h, and removing the organic template machine by burning to obtain the Zn-MFI molecular sieve solid.
In the step b), the addition amount of the Zn source is SiO 2 1 to 10 percent of (A).
The organic template R in the step a) is selected from at least one of tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapropylammonium bromide and tetrabutylammonium bromide; the silicon source is at least one of tetraethoxysilane and silica sol;
said Zn source in step b) is zinc gluconate.
As an embodiment, the application discloses the application of the catalyst prepared by the preparation method in the reaction of preparing low-carbon olefin by propane dehydrogenation.
Specifically, raw material gas containing propane is introduced into a reactor filled with the catalyst to react under certain conditions, wherein the reaction temperature is 500-650 ℃, and the mass space velocity is 0.6-2.4 h -1 。
Example 1 preparation of 1.5% Zn-MFI molecular sieves
46.9g of deionized water, 42.3g of tetraethoxysilane (Si source) and 65.1g of tetrapropylammonium hydroxide (organic template agent) are weighed, sequentially added and uniformly stirred at the temperature of 60 ℃ for 2 hours to obtain transparent primary synthetic sol. According to SiO 2 Adding 1.25g of zinc gluconate (Zn source) according to the mass percentage, aging and stirring to synthesize a solution for 6 hours to obtain the final sol.
In the primary synthesis sol described above, in terms of molar ratios, the following are satisfied:
OSDA (organic templating agent): siO 2 2 ＝2:1；
H 2 O：SiO 2 ＝175:1
And SiO contained as Si source in the primary synthesis sol 2 The mass percent of the zinc element is 1.5 percent, and the Zn source is added (based on the mass of the zinc element).
And (3) introducing the final sol into a stainless steel crystallization reaction kettle, heating the crystallization kettle to 170 ℃, and staying for 72 hours to enable the mixed sol to complete the hydrothermal synthesis crystallization reaction. After the reaction is finished, quickly cooling the reaction kettle, centrifugally filtering and washing the formed crystals until the pH value of a washing liquid is 8, drying the obtained solid product at 120 ℃ for 7 hours, and roasting at 550 ℃ for 4 hours to obtain a Zn-MFI molecular sieve solid, wherein the SEM (scanning electron microscope) result is shown in figure 1, which shows that the synthesized Zn-MFI molecular sieve is spherical grains with the size of about 200nm; the XRD (X-ray diffraction) results are MFI structures, as shown in FIG. 2 a.
Example 2 preparation of 2.0%
The operation of example 1 was repeated except that the amount of zinc gluconate (Zn source) was changed from 1.25g to 1.67g during the synthesis to obtain the Zn-MFI molecular sieve of the present invention.
In the primary synthesis sol described above, in terms of molar ratios, the following are satisfied:
OSDA (organic templating agent): siO 2 2 ＝2:1；
H 2 O：SiO 2 ＝175:1
And SiO is used in the primary synthetic sol 2 When 2.0% by mass of Zn source was added, XRD showed MFI structure, as shown in FIG. 2 b.
Example 3 preparation of 3.1%
The operation of example 1 was repeated except that the amount of zinc gluconate (Zn source) used in the synthesis process was changed from 1.25g to 2.59g, to obtain a Zn-MFI molecular sieve solid of the present invention.
In the primary synthesis sol, in terms of molar ratio, the following are satisfied:
OSDA (organic templating agent): siO 2 2 ＝2:1；
H 2 O：SiO 2 ＝175:1
And SiO is used in the primary synthetic sol 2 When 3.1% by mass of Zn source was added, XRD showed MFI structure, as shown in FIG. 2 c.
Example 4 preparation of 1.5% Zn-MFI molecular sieves
During the synthesis, the Si source was changed from 42.3g of tetraethoxysilane to 40.1g of silica Sol (SiO) 2 Content 30%), the procedure of example 1 was repeated to obtain the Zn-MFI molecular sieve of the present invention.
In the primary synthesis sol described above, in terms of molar ratios, the following are satisfied:
OSDA (organic templating agent): siO 2 2 ＝2:1；
H 2 O：SiO 2 ＝175:1
And SiO is used in the primary synthetic sol 2 The Zn source is added in the mass percent of 1.5%. The XRD result is MFI structure as shown in fig. 2 d.
Example 5 preparation of 1.5% Zn-MFI molecular sieves
The operation of example 1 was repeated to change the organic template from 65.1g of tetrapropylammonium hydroxide to 83.1g of tetrabutylammonium hydroxide during the synthesis process to obtain the Zn-MFI molecular sieve of the present invention.
In the primary synthesis sol described above, in terms of molar ratios, the following are satisfied:
OSDA (organic templating agent): siO 2 2 ＝2:1；
H 2 O：SiO 2 ＝175:1
With SiO 2 The mass percent of the Zn source is 1.5%, and the XRD result shows that the MFI structure is shown in figure 2 f.
Comparative example 1 preparation of 1.5% Zn/SiO 2 Catalyst and process for preparing same
Weighing 10g of deionized water and 0.25g of zinc gluconate (Zn source), and stirring to fully dissolve to form a zinc gluconate solution. Weighing 2.4g of fumed silica, pouring the fumed silica into a beaker filled with the zinc gluconate solution, uniformly stirring, soaking for 12h, and evaporating to remove water in a water bath kettle at 60 ℃. The obtained solid product is dried for 7h at the temperature of 120 ℃ and then roasted for 4h at the temperature of 550 ℃ to obtain Zn/SiO with the Zn content of 1.5 percent corresponding to the embodiment 1 2 And (3) raw catalyst powder.
Comparative example 2 preparation of 2.0% Zn/SiO 2 Catalyst and process for preparing same
10g of deionized water and 0.33g of zinc gluconate (Zn source) are weighed and stirred to be fully dissolved to form a zinc gluconate solution. Weighing 2.4g of fumed silica, pouring the fumed silica into a beaker filled with the zinc gluconate solution, uniformly stirring, soaking for 12h, and evaporating to remove water in a water bath kettle at 60 ℃. The obtained solid product is dried for 7h at the temperature of 120 ℃ and then roasted for 4h at the temperature of 550 ℃ to obtain Zn/SiO with the Zn content of 2.0 percent corresponding to the embodiment 2 2 And (3) raw catalyst powder.
Comparative example 3 preparation of 3.1% 2 Catalyst and process for preparing same
10g of deionized water and 0.52g of zinc gluconate (Zn source) are weighed and stirred to be fully dissolved to form a zinc gluconate solution. 2.4g of fumed silica is weighed and poured into a beaker filled with the zinc gluconate solution, the mixture is stirred uniformly, and the mixture is immersed for 12 hours and then is evaporated to dryness in a water bath kettle at 60 ℃. The resulting solid product was dried at 120 deg.CDrying for 7h, and roasting at 550 ℃ for 4h to obtain Zn/SiO with Zn content of 3.1 percent corresponding to example 3 2 And (3) raw catalyst powder.
Comparative example 4 Synthesis of Zn-MFI catalyst from Zinc nitrate
46.9g of deionized water, 42.3g of tetraethoxysilane (Si source) and 65.1g of tetrapropylammonium hydroxide (organic template agent) are weighed, sequentially added and uniformly stirred at the temperature of 60 ℃, and the transparent primary synthetic sol is obtained after 2 hours of stirring. According to SiO 2 0.73g of zinc nitrate (Zn source) is added according to the mass percentage, and the mixture is aged and stirred to synthesize a solution for 6 hours to obtain the final sol.
In the primary synthesis sol described above, in terms of molar ratios, the following are satisfied:
OSDA (organic templating agent): siO 2 2 ＝2:1；
H 2 O：SiO 2 ＝175:1
And SiO contained as Si source in the primary synthesis sol 2 The mass percent is 2.0 percent, and Zn source (based on the mass of the zinc element) is added.
And (3) introducing the final sol into a stainless steel crystallization reaction kettle, heating the crystallization kettle to 170 ℃, and staying for 72 hours to enable the mixed sol to complete the hydrothermal synthesis crystallization reaction. After the reaction is finished, quickly cooling the reaction kettle, centrifugally filtering and washing the formed crystals until the pH value of a washing liquid is 8, drying the obtained solid product at 120 ℃ for 7h, and roasting at 550 ℃ for 4h to obtain the Zn-MFI molecular sieve solid.
Comparative example 5 Synthesis of Zn-MFI catalyst with Zinc acetate
46.9g of deionized water, 42.3g of tetraethoxysilane (Si source) and 65.1g of tetrapropylammonium hydroxide (organic template agent) are weighed, sequentially added and uniformly stirred at the temperature of 60 ℃, and the transparent primary synthetic sol is obtained after 2 hours of stirring. According to SiO 2 0.71g of zinc acetate (Zn source) is added according to the mass percentage to be aged and stirred to synthesize a solution for 6 hours, and then the final sol is obtained.
In the primary synthesis sol described above, in terms of molar ratios, the following are satisfied:
OSDA (organic templating agent): siO 2 2 ＝2:1；
H 2 O：SiO 2 ＝175:1
And SiO contained as a Si source in the primary synthesis sol 2 The mass percent is 2.0 percent, and Zn source amount (based on the mass of the zinc element) is added.
And (3) introducing the final sol into a stainless steel crystallization reaction kettle, heating the crystallization kettle to 170 ℃, and staying for 72 hours to enable the mixed sol to complete the hydrothermal synthesis crystallization reaction. After the reaction is finished, quickly cooling the reaction kettle, centrifugally filtering and washing the formed crystals until the pH value of a washing liquid is 8, drying the obtained solid product at 120 ℃ for 7 hours, and roasting at 550 ℃ for 4 hours to obtain the Zn-MFI molecular sieve solid.
Example 6Zn-MFI molecular Sieve catalyst and Zn/SiO 2 Application of catalyst in preparation of propylene by propane dehydrogenation
1.5% of the Zn-MFI molecular sieve prepared in example 1 was granulated to obtain catalyst # 1. Catalyst 1# was placed in a reactor and 5% propane (95% Ar equilibrium gas) was passed through at a reaction temperature of 550 ℃ and a space velocity of 0.6h -1 The reaction for producing propylene by dehydrogenation of propane was carried out, and the reaction results are shown in FIG. 3 and Table 1.
2.0% of the Zn-MFI molecular sieve prepared in example 2 was granulated to obtain catalyst # 2. Catalyst 2# was placed in a reactor and 5% propane (95% Ar equilibrium gas) was passed through at a reaction temperature of 550 ℃ and a space velocity of 0.6h -1 The reaction for producing propylene by dehydrogenation of propane was carried out, and the reaction results are shown in FIG. 3 and Table 1.
Granulating 3.1% of Zn-MFI molecular sieve obtained in example 3 to obtain catalyst # 3. Placing catalyst No. 3 in a reactor, introducing 5% propane (95% Ar balance gas), reaction temperature 550 deg.C, space velocity 0.6h -1 The reaction for producing propylene by dehydrogenation of propane was carried out, and the reaction results are shown in FIG. 3 and Table 1.
2.0% of the Zn-MFI molecular sieve prepared in example 2 was granulated to obtain catalyst # 2. Placing catalyst 2# in a reactor, introducing 5% propane (95% Ar equilibrium gas) at reaction temperature of 525 deg.C, 550 deg.C, 580 deg.C, and space velocity of 0.6h -1 The reaction for producing propylene by dehydrogenation of propane was carried out, and the reaction results are shown in FIG. 4.
Will be paired with1.5% of ZnSiO prepared in proportion 1 2 Catalyst and granulating to obtain catalyst No. 16. Catalyst 16# was placed in the reactor and 5% propane (95% Ar equilibrium gas) was passed through at a reaction temperature of 550 ℃ and a space velocity of 0.6h -1 The reaction for producing propylene by dehydrogenation of propane was carried out, and the reaction results are shown in table 1.
2.0% of ZnSiO obtained in comparative example 2 2 Catalyst, granulating to obtain catalyst No. 26. Catalyst 26# was placed in the reactor and 5% propane (95% Ar equilibrium gas) was passed through at a reaction temperature of 550 ℃ and a space velocity of 0.6h -1 The reaction for producing propylene by dehydrogenation of propane was carried out, and the reaction results are shown in Table 1.
3.1% of ZnSiO obtained in comparative example 3 2 Catalyst, granulating to obtain catalyst No. 36. Catalyst 36# was placed in a reactor and 5% propane (95% Ar equilibrium gas) was passed through at a reaction temperature of 550 ℃ and a space velocity of 0.6h -1 The reaction for producing propylene by dehydrogenation of propane was carried out, and the reaction results are shown in Table 1.
Granulating the Zn-MFI catalyst obtained in comparative example 4 in 2.0% to obtain catalyst # 46. Catalyst 46# was placed in the reactor and 5% propane (95% Ar equilibrium gas) was passed through at a reaction temperature of 550 ℃ and a space velocity of 0.6h -1 The reaction for producing propylene by dehydrogenation of propane was carried out, and the reaction results are shown in Table 1.
2.0% of the Zn-MFI catalyst obtained in comparative example 5, and granulating to obtain catalyst # 56. Catalyst 56# was placed in the reactor and 5% propane (95% Ar balance gas) was passed through at a reaction temperature of 550 ℃ and a space velocity of 0.6h -1 The reaction for producing propylene by dehydrogenation of propane was carried out, and the reaction results are shown in Table 1.
TABLE 1 reaction results of the catalyst in the dehydrogenation of propane to propylene
Through the analysis of the data, the following results are obtained: the Zn-MFI catalyst has good propane dehydrogenation performance and propylene selectivity. The propane conversion rate is over 22 percent, the propylene selectivity is maintained over 95 percent, and the highest propylene selectivity can reach 98.3 percent. Therefore, compared with Zn-SiO, the Zn-MFI catalyst provided by the invention is applied to preparing propylene by propane dehydrogenation 2 The Zn-MFI catalyst synthesized by the catalyst and other Zn sources has greatly improved catalytic activity, high conversion rate and high propylene selectivity, and has more efficient reaction performance.
Although the present invention has been described with reference to a few preferred embodiments, it should be understood that various changes and modifications can be made without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A preparation method of a Zn-MFI molecular sieve is characterized by comprising the following steps:
a) Mixing materials containing a silicon source, an organic template agent R and water to obtain primary sol;
in terms of mole ratios, the primary sol satisfies:
R：SiO 2 ＝0.3～15：1；
H 2 O：SiO 2 ＝20～1000：1；
wherein the mole number of the template agent R is calculated by the total mole number of the template agent contained in the template agent R;
the mole number of the silicon source is SiO contained in the silicon source 2 Calculating the mole number of the active carbon;
the number of moles of water is calculated as its own number of moles;
b) Adding a Zn source into the primary sol, and aging to obtain a final sol;
the Zn source comprises zinc gluconate;
c) And carrying out hydrothermal crystallization on the final sol, and removing the template agent to obtain the Zn-MFI molecular sieve.
2. The method according to claim 1, wherein in step b), the Zn source is added in an amount of 1 to 10wt% based on the silicon source;
wherein the mass of the Zn source is calculated by the mass of Zn element;
the mass of the silicon source is SiO contained in the silicon source 2 The mass of (2) is calculated.
3. The method according to claim 2, wherein the Zn source is added in an amount of 1 to 5wt% based on the silicon source in the step b).
4. The method according to claim 1, wherein in step b), the aging conditions comprise:
the aging time is 3-24 h.
5. The preparation method according to claim 1, wherein in step a), the silicon source comprises at least one of tetraethoxysilane and silica sol;
the organic template agent R comprises at least one of tetrapropyl ammonium hydroxide, tetrabutyl ammonium hydroxide, tetrapropyl ammonium bromide and tetrabutyl ammonium bromide.
6. The method according to claim 1, wherein the mixing in step a) is stirring mixing, and the stirring conditions include:
the stirring temperature is 50-80 ℃, and the stirring time is 2-6 h.
7. The method according to claim 1, wherein in step c), the hydrothermal crystallization conditions include:
the hydrothermal crystallization temperature is 150-200 ℃, and the hydrothermal crystallization time is 60-120 h;
the template agent is removed by roasting, and the roasting conditions comprise that:
the roasting temperature is 500-600 ℃, and the roasting time is 4-12 h.
8. The method according to claim 1, wherein the step c) further comprises the following steps before removing the template agent:
separating and drying the solid in the crystallized product;
the drying conditions include:
the drying temperature is 80-120 ℃, and the drying time is 5-10 h.
9. A method for preparing low-carbon olefin by propane dehydrogenation is characterized by comprising the following steps:
reacting a feed gas containing propane under the action of a catalyst to obtain the low-carbon olefin;
the catalyst comprises the Zn-MFI molecular sieve prepared by the preparation method of any one of claims 1 to 8.
10. The method of claim 7, wherein the reaction conditions comprise:
the reaction temperature is 500-650 ℃, the mass space velocity of the feed gas is 0.6-2.4 h -1 ；
Preferably, the feed gas comprises propane and a balance gas;
the volume ratio of the propane to the balance gas is 5-20: 80 to 95.
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| JPH07278567A (en) * | 1994-04-06 | 1995-10-24 | Idemitsu Kosan Co Ltd | Catalytic conversion of hydrocarbon |
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| JPH07278567A (en) * | 1994-04-06 | 1995-10-24 | Idemitsu Kosan Co Ltd | Catalytic conversion of hydrocarbon |
| CN106552664A (en) * | 2015-09-30 | 2017-04-05 | 中国石油化工股份有限公司 | A kind of highly active catalytic cracks alkene catalyst processed and preparation method thereof |
| CN112844445A (en) * | 2021-02-03 | 2021-05-28 | 中国石油大学(北京) | Preparation and application of ZnCo-based bimetallic catalyst for limitation of microporous pore canals of Silicalite-1 molecular sieve |
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