CN115845917A - Preparation method and application of micron Au/TS-1 catalyst for propylene gas-phase epoxidation reaction in oxyhydrogen system - Google Patents
Preparation method and application of micron Au/TS-1 catalyst for propylene gas-phase epoxidation reaction in oxyhydrogen system Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims abstract description 47
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 title claims abstract description 31
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 title claims abstract description 29
- 238000006735 epoxidation reaction Methods 0.000 title claims abstract description 22
- 238000002360 preparation method Methods 0.000 title claims abstract description 13
- 239000010936 titanium Substances 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 21
- GOOHAUXETOMSMM-UHFFFAOYSA-N Propylene oxide Chemical compound CC1CO1 GOOHAUXETOMSMM-UHFFFAOYSA-N 0.000 claims abstract description 15
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 15
- 238000001694 spray drying Methods 0.000 claims abstract description 9
- 238000003756 stirring Methods 0.000 claims description 30
- 239000000203 mixture Substances 0.000 claims description 22
- 239000000243 solution Substances 0.000 claims description 22
- 239000002808 molecular sieve Substances 0.000 claims description 19
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- 238000006243 chemical reaction Methods 0.000 claims description 16
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- 238000001035 drying Methods 0.000 claims description 14
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- 239000007789 gas Substances 0.000 claims description 10
- LPSKDVINWQNWFE-UHFFFAOYSA-M tetrapropylazanium;hydroxide Chemical compound [OH-].CCC[N+](CCC)(CCC)CCC LPSKDVINWQNWFE-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 9
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- 150000002431 hydrogen Chemical class 0.000 claims description 8
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- 229910052786 argon Inorganic materials 0.000 claims description 2
- 239000001307 helium Substances 0.000 claims description 2
- 229910052734 helium Inorganic materials 0.000 claims description 2
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 2
- 230000002572 peristaltic effect Effects 0.000 claims description 2
- -1 polytetrafluoroethylene Polymers 0.000 claims description 2
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- 239000012495 reaction gas Substances 0.000 claims description 2
- UQMOLLPKNHFRAC-UHFFFAOYSA-N tetrabutyl silicate Chemical compound CCCCO[Si](OCCCC)(OCCCC)OCCCC UQMOLLPKNHFRAC-UHFFFAOYSA-N 0.000 claims description 2
- LFQCEHFDDXELDD-UHFFFAOYSA-N tetramethyl orthosilicate Chemical compound CO[Si](OC)(OC)OC LFQCEHFDDXELDD-UHFFFAOYSA-N 0.000 claims description 2
- 229940095070 tetrapropyl orthosilicate Drugs 0.000 claims description 2
- ZQZCOBSUOFHDEE-UHFFFAOYSA-N tetrapropyl silicate Chemical compound CCCO[Si](OCCC)(OCCC)OCCC ZQZCOBSUOFHDEE-UHFFFAOYSA-N 0.000 claims description 2
- BGQMOFGZRJUORO-UHFFFAOYSA-M tetrapropylammonium bromide Chemical compound [Br-].CCC[N+](CCC)(CCC)CCC BGQMOFGZRJUORO-UHFFFAOYSA-M 0.000 claims description 2
- FBEVECUEMUUFKM-UHFFFAOYSA-M tetrapropylazanium;chloride Chemical compound [Cl-].CCC[N+](CCC)(CCC)CCC FBEVECUEMUUFKM-UHFFFAOYSA-M 0.000 claims description 2
- POSYVRHKTFDJTR-UHFFFAOYSA-M tetrapropylazanium;fluoride Chemical compound [F-].CCC[N+](CCC)(CCC)CCC POSYVRHKTFDJTR-UHFFFAOYSA-M 0.000 claims description 2
- 238000009834 vaporization Methods 0.000 claims description 2
- 230000008016 vaporization Effects 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims 1
- 239000010931 gold Substances 0.000 abstract description 28
- 230000003197 catalytic effect Effects 0.000 abstract description 6
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 abstract description 5
- 238000001027 hydrothermal synthesis Methods 0.000 abstract description 5
- 229910052737 gold Inorganic materials 0.000 abstract description 4
- 238000006555 catalytic reaction Methods 0.000 abstract description 2
- 230000008021 deposition Effects 0.000 abstract description 2
- 238000001556 precipitation Methods 0.000 abstract description 2
- 239000000047 product Substances 0.000 description 16
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- 230000015572 biosynthetic process Effects 0.000 description 4
- YHWCPXVTRSHPNY-UHFFFAOYSA-N butan-1-olate;titanium(4+) Chemical compound [Ti+4].CCCC[O-].CCCC[O-].CCCC[O-].CCCC[O-] YHWCPXVTRSHPNY-UHFFFAOYSA-N 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
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- 238000005507 spraying Methods 0.000 description 4
- 241000282326 Felis catus Species 0.000 description 3
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 3
- APQHKWPGGHMYKJ-UHFFFAOYSA-N Tributyltin oxide Chemical compound CCCC[Sn](CCCC)(CCCC)O[Sn](CCCC)(CCCC)CCCC APQHKWPGGHMYKJ-UHFFFAOYSA-N 0.000 description 3
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- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 229910004339 Ti-Si Inorganic materials 0.000 description 2
- 229910010978 Ti—Si Inorganic materials 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
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- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 2
- 241000894007 species Species 0.000 description 2
- 239000002028 Biomass Substances 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- MWRWFPQBGSZWNV-UHFFFAOYSA-N Dinitrosopentamethylenetetramine Chemical compound C1N2CN(N=O)CN1CN(N=O)C2 MWRWFPQBGSZWNV-UHFFFAOYSA-N 0.000 description 1
- 241001411320 Eriogonum inflatum Species 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 239000004721 Polyphenylene oxide Substances 0.000 description 1
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- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
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Abstract
The invention belongs to the technical field of petrochemical engineering catalysis, and discloses a preparation method and application of a micron Au/TS-1 catalyst for propylene gas-phase epoxidation reaction in an oxyhydrogen system, and the micron Au/TS-1 catalyst is applied to the propylene gas-phase epoxidation reaction in the oxyhydrogen system. Micron TS-1 is synthesized by a spray drying assisted hydrothermal method, and gold is loaded on a TS-1 carrier by a deposition precipitation method. The method solves the problem that the TS-1 carrier prepared by a classical hydrothermal synthesis method is not easy to separate, and has high crystallinity and framework titanium content. The micron Au/TS-1 catalyst shows good catalytic performance and stability in propylene gas-phase epoxidation reaction, the propylene oxide generation rate is superior to that of a small-crystal-grain Au/TS-1 catalyst synthesized by a classical method in a hydrothermal mode, and the micron Au/TS-1 catalyst has an industrial application prospect.
Description
Technical Field
The invention belongs to the technical field of petrochemical industry catalysis, and particularly relates to a preparation method of a micron Au/TS-1 catalyst for propylene gas-phase epoxidation, in particular to a catalyst for propylene gas-phase epoxidation under the condition of an oxyhydrogen system.
Background
Propylene Oxide (PO) is an important chemical raw material for producing polyether polyol, propylene glycol, dimethyl carbonate and the like, and the market demand is huge. The Haruta project group (Research on chemical intermediates,1998,24.3, 329-336.) reported for the first time in 1998 that hydrogen, oxygen, propylene cofeeds effect the gas phase epoxidation of propylene in the presence of an Au-Ti based catalyst system. The epoxidation process has high atom utilization rate, and the byproduct is mainly water, so that the epoxidation process is a green catalytic process.
Titanium silicalite molecular sieve (TS-1) is widely used in propylene gas phase epoxidation reaction as a catalyst carrier. Currently, the TS-1 preparation mainly adopts a hydrothermal crystallization method, and a target product TS-1 molecular sieve is obtained by separating, washing, drying and roasting a product after crystallization is finished. The size of the TS-1 molecular sieve prepared in a classic method hydrothermal synthesis system is mainly focused on 200-500nm, so the currently published documents and patents are mainly focused on the research on the aspects of modification, reduction mode, feed composition and the like of small-grain Au/TS-1.
For example, huangjiahui et al (CN 109928942A) discloses the use of two basic metal (Li, cs, na and Rb) salts (carbonate, nitrate, sulfate, phosphate) mixed as precipitants to prepare bimetallic promoter modified gold catalysts with improved catalyst performance. In the patent (CN 109926098A), the supported Au/TS-1 catalyst is modified by alkaline gas, and the production rate of the modified propylene oxide is greatly improved. The patent (CN 107961814A) discloses pretreatment of catalyst with raw materials of propylene, oxygen and hydrogen, followed by epoxidation of propylene under normal pressure. The catalyst reduced by the method shows very good activity in propylene epoxidation reaction, and the generation rate of propylene oxide is greatly improved. The patent (CN 112871205A) discloses that defect site auxiliary agents (such as soluble starch, polyacrylamide and the like) and S-containing auxiliary agents (such as sodium sulfite, potassium bisulfite and the like) are added in the preparation process of the catalyst to obtain titanium-rich and large amount of defect sites suitable for Au loading, and amorphous titanium species on the catalyst are stabilized by S species, so that the high-activity propylene gas-phase epoxidation catalyst is obtained. The alkali metal ions introduced together with the S auxiliary agent can reduce the selectivity of the by-product and greatly improve the conversion rate of propylene, the selectivity of PO and the hydrogen efficiency. Patents (CN 109529927A and CN 109569716A) by shozui et al disclose Ga and Fe modified Au/TS-1 catalysts, which all improve the performance of the catalysts to different degrees. The patent (CN 113368895A) discloses that Au/TS-1 is modified by a biomass active agent and ammonium salt, gold atoms can be anchored better in the modification preparation process, the capture rate of gold is improved, the number of effective gold sites is increased, and the production rate of propylene oxide is improved by 15 times. Patent of Zhao Chenyang et al (CN 113912571A) discloses that introducing a small amount of propane into a raw material gas significantly prolongs the service life of a catalyst in a propylene epoxidation reaction, and also improves reaction selectivity and propylene conversion rate.
The publication (Journal of Materials Chemistry A6.20 (2018): 9473-9479.) reports that smaller grain size is beneficial for the catalyst to expose more active sites and better diffusion performance. The publication (Chemical Engineering Science 227 (2020): 115907.) reports that small-sized TS-1 improves PO production rate, selectivity, and hydrogen efficiency ratio due to the synergistic effect of Au-Ti. As a carrier of Au/TS-1 catalyst, researchers have made many attempts to synthesize small-sized TS-1 in order to obtain more reactive active sites, shorten the diffusion distance of organic substances in the catalyst, and improve the reaction performance of the catalyst. The publication can further reduce the crystal size by increasing the amount of organic templating agent (nanoscale, 2013,5, 6693-6703.), the solid conversion method (micropor.meso. Mater, 2015,217, 96-101.), the utilization of organosilane as a silicon source (mater.lett, 2012,68, 1-3.), the introduction of seed crystals to shorten the time of crystal synthesis (patent CN 109250726A), and other strategies.
In terms of carriers, small crystal particles TS-1 are not beneficial to solid-liquid separation, and membrane filtration is generally adopted industrially. In order to solve the problem of low separation efficiency, people often adopt means such as adding ammonium salt, alkali or a mixture of alkali and salt into a molecular sieve slurry to promote the flocculation of the molecular sieve and improve the filtration efficiency, but other heteroatoms are introduced at the same time to influence the catalytic performance of the molecular sieve. Centrifugal separation techniques are generally only suitable for small scale separations in laboratories due to their low separation efficiency. Compared with small crystal grain TS-1, the micron-size TS-1 separation method is relatively simple, and currently, a plate-frame filtration method is commonly adopted by several large domestic enterprises, so that the method is more efficient and rapid in the solid-liquid separation link. Therefore, the Au/TS-1 catalyst with easily separated synthetic carrier and good catalytic performance can simplify the synthetic steps and reduce the energy consumption, and has important significance for the application of the catalyst.
Disclosure of Invention
The invention relates to a preparation method of an Au/TS-1 catalyst suitable for propylene gas-phase epoxidation reaction in an oxyhydrogen system. Adopts the technology of spray drying assisted hydrothermal synthesis of molecular sieve under the condition of low dosage of template agent (TPAOH: siO) 2 The molar ratio is 0.05), and H in the hydrothermal crystallization system is adjusted 2 O:SiO 2 Preparing the TS-1 carrier with the micron-sized size of (2-5 um). The product is easy for solid-liquid separation, and has higher crystallinity and good titanium distribution. The micron Au/TS-1 catalyst prepared by the gold deposition precipitation method has good catalytic performance and stability in propylene gas phase epoxidation reaction, and has potential industrial application prospect.
The technical scheme of the invention is as follows:
a method for preparing micron-sized Au/TS-1 catalyst for gas phase epoxidation of propylene in hydrogen and oxygen system, the method comprising the steps of:
(1) Dripping a titanium source into hydrochloric acid, adding deionized water, and stirring until the solution is clear; then adding a silicon source and continuously stirring for 30min to obtain a clear solution, wherein the molar ratio of each component is as follows: siO 2 2 :TiO 2 :H 2 O: HCl =1:0.0167-0.0333:20:0.067; spraying the obtained solution by a spray drying device, and drying to obtain titanium silicon amorphous powder A; conditions of the spray-drying apparatus: the temperature of the vaporization chamber is 180-300 ℃, and the feeding rate of the peristaltic pump is 7-20 mL/min -1 The frequency of the fan is 80Hz;
(2) Adding 25wt% or 40wt% of template agent aqueous solution and deionized water into the titanium silicon amorphous powder A, stirring to completely immerse the titanium silicon amorphous powder A into the template agent aqueous solution, wherein the molar ratio of each component of the final mixture is as follows: s. theiO 2 :TiO 2 : template agent: h 2 O=1:(0.01-0.033):(0.05-0.2):(0.85-3.4);
(3) Putting the mixture obtained in the step (2) into a stainless steel crystallization kettle with a polytetrafluoroethylene lining, then putting the stainless steel crystallization kettle into a rotary oven for rolling or static crystallization at the temperature of 130-210 ℃, washing the mixture to be neutral by deionized water after crystallization for 24-72h, drying the mixture at the temperature of 90-110 ℃, and finally roasting the mixture at the temperature of 450-650 ℃ for 10h to remove a template agent to obtain the TS-1 molecular sieve;
(4) Taking the concentration as 7.6x10 -3 Adding the TS-1 molecular sieve carrier obtained in the step (3) into a mol/L chloroauric acid aqueous solution, wherein the mass ratio of the TS-1 molecular sieve carrier to the chloroauric acid is (9-10): 1, with 1M and 0.1MNa, respectively 2 CO 3 The pH value of the solution adjusting system is 7.9-8.0, the solution is stirred for 6 hours at 35 ℃, then is filtered, washed and dried for 10 hours at 35 ℃ in vacuum, the obtained product is pressed into tablets and sieved by a 20-40 mesh sieve, and the volume ratio is 1:1:7, reducing for 2 hours in a mixed atmosphere of hydrogen, propylene and nitrogen to prepare the Au/TS-1 catalyst.
Further, in the step (1), the stirring temperature is 25-40 ℃, and the stirring time is 2-12h; and (3) stirring at room temperature in the step (2).
Further, in the step (1), the silicon source is one or a mixture of more than two of tetraethyl orthosilicate, tetramethyl orthosilicate, tetrapropyl orthosilicate and tetrabutyl orthosilicate, or one or a mixture of two of silica sol and white carbon black.
Further, in the step (2), the template agent is one or a mixture of more than two of tetrapropyl ammonium hydroxide, tetrapropyl ammonium bromide, tetrapropyl ammonium chloride and tetrapropyl ammonium fluoride.
Further, the molar ratio of silicon to titanium of the titanium silicalite molecular sieve is 30-100; the content of framework titanium is 1.3-4.2wt%; the molar ratio of the substances in the silicon-titanium amorphous powder A in the step (2) is SiO 2 :TiO 2 : template agent: h 2 O=1:0.0167-0.0333:0.05:0.85-3.4。
Further, in the step (3), the roasting atmosphere is one or a mixture of more than two of air, nitrogen, argon, helium and ammonia.
The catalyst prepared by the method is applied to preparing propylene oxide by propylene gas phase epoxidation under an oxyhydrogen system, the reaction is carried out in a normal pressure fixed bed reaction device, the reaction temperature is 80-300 ℃, and the volume ratio of the components of reaction gas is C 3 H 6 /H 2 /O 2 /N 2 =1/1/1/7, and the space velocity is 4000-20000mL · h -1 ·Kg -1 cat.。
The invention has the beneficial effects that: the micron-sized TS-1 carrier solves the problem that the TS-1 is not easy to separate in the hydrothermal synthesis by a classical method, and has high crystallinity (figure 2) and framework titanium content (figure 3). The Au/TS-1 catalyst showed good catalytic performance and stability in propylene gas phase epoxidation (FIG. 4), and propylene oxide formation rate (213.4 g) PO ·Kg cat· -1 ·h -1 ) Is superior to Au/TS-1 catalyst (138.1 g) synthesized by a classical method in a hydrothermal way PO ·Kg cat· -1 ·h -1 ) And has industrial application prospect.
Drawings
FIG. 1 (a) is an SEM photograph of a support according to example 3 of the present invention;
FIG. 1 (b) is an SEM photograph of a carrier in example 2 of the present invention;
FIG. 1 (c) is an SEM photograph of a support according to example 1 of the present invention;
FIG. 1 (d) is a graph showing the distribution of particle size distribution of a carrier in example 3 of the present invention;
FIG. 1 (e) is a graph showing the particle size distribution of a carrier in example 2 of the present invention;
FIG. 1 (f) is a graph showing the particle size distribution of a carrier in example 1 of the present invention;
FIG. 2 is an XRD pattern of the support of examples 1-3 of the present invention;
FIG. 3 is a UV-Vis diagram of the supports of examples 1 to 3 according to the invention and of the support of comparative example 1;
FIG. 4 is a graph of PO formation rate as a function of time for the catalysts of examples 1-3 of the present invention and the catalyst of comparative example 1.
Detailed Description
Example 1
Tetrabutyl titanate (TBOT) 4.26g was added dropwise to hydrochloric acid 5g (12 mol/L), water 270g was added after stirring well, ethyl orthosilicate (TEOS) 156.3g was added after stirring in a water bath for 10-15min, and stirring was continued for 2h to obtain solution A with Si/Ti = 60.
Spray drying the prepared solution A at 220 ℃ by adopting an aerosol spraying device to obtain amorphous precursor powder of 60 Ti-Si with Si/Ti, and marking as A 1 . Weighing the precursor powder A 1 5g, respectively adding 3.4g of 25wt.% tetrapropylammonium hydroxide (TPAOH) aqueous solution, adding 2.55g of water, uniformly stirring, placing in a reaction kettle, and performing rolling crystallization at 170 ℃ for 48 hours. Cooling and washing the crystallized product until the filtrate is neutral, drying at 110 deg.C overnight, and calcining at 550 deg.C in air atmosphere for 10h to obtain TS-1 (60) -3.4 carrier with average size of about 2976nm, as shown in FIGS. 1 (c) and (f).
Taking 5mL of chloroauric acid aqueous solution with the concentration of 0.04867mol/L, adding 27mL of deionized water for dilution, adding 0.8g of the TS-1 molecular sieve carrier obtained above, and respectively using 1M and 0.1M Na 2 CO 3 And (2) adjusting the pH value of the solution adjusting system to be 7.9-8.0, stirring for 6h at 35 ℃, then performing suction filtration and washing, then drying for about 10h at 35 ℃ under vacuum, tabletting and sieving the obtained product for 20-40 meshes, and reducing 0.15g of the product for 2h at 300 ℃ in the atmosphere of hydrogen, propylene and nitrogen to obtain the Au/TS-1 (60) -2976nm catalyst.
Example 2
Tetrabutyl titanate (TBOT) 4.26g was added dropwise to hydrochloric acid 5g (12 mol/L), water 270g was added after stirring well, ethyl orthosilicate (TEOS) 156.3g was added after stirring in a water bath for 10-15min, and stirring was continued for 2h to obtain solution A with Si/Ti = 60.
Spray drying the prepared solution A at 220 ℃ by adopting an aerosol spraying device to obtain amorphous precursor powder of titanium silicon with Si/Ti of 60, and marking as A 1 . Weighing the precursor powder A 1 5g, adding 3.4g of 25wt.% tetrapropylammonium hydroxide (TPAOH) aqueous solution, uniformly stirring, putting into a reaction kettle, and carrying out rolling crystallization at 170 ℃ for 48 hours. Cooling and washing the crystallized product until the filtrate is neutral, drying at 110 deg.C overnight, and calcining at 550 deg.C in air atmosphere for 10h to obtain TS-1 (60) -1.7 carrier with average size of about 802nm, as shown in FIGS. 1 (b), (e).
Taking chloroauric acid with the concentration of 0.04867mol/L5mL of the aqueous acid solution was diluted with 27mL of deionized water, and 0.8g of the TS-1 molecular sieve support obtained above was added thereto with 1M and 0.1M Na, respectively 2 CO 3 And (2) adjusting the pH value of the solution adjusting system to be 7.9-8.0, stirring for 6h at 35 ℃, then performing suction filtration and washing, then drying for about 10h at 35 ℃ under vacuum, tabletting and sieving the obtained product for 20-40 meshes, and reducing 0.15g of the product for 2h at 300 ℃ in the atmosphere of hydrogen, propylene and nitrogen to obtain the Au/TS-1 (60) -1.7 catalyst.
Example 3
Tetrabutyl titanate (TBOT) 4.26g was added dropwise to hydrochloric acid 5g (12 mol/L), water 270g was added after stirring well, ethyl orthosilicate (TEOS) 156.3g was added after stirring in a water bath for 10-15min, and stirring was continued for 2h to obtain solution a with Si/Ti = 60.
Spray drying the prepared solution A at 220 ℃ by adopting an aerosol spraying device to obtain amorphous precursor powder of 60 Ti-Si with Si/Ti, and marking as A 1 . Weighing the precursor powder A 1 5g, adding 3.4g of 40wt.% tetrapropylammonium hydroxide (TPAOH) aqueous solution, uniformly stirring, putting into a reaction kettle, and carrying out rolling crystallization at 170 ℃ for 48 hours. Cooling and washing the crystallized product until the filtrate is neutral, drying at 110 deg.C overnight, and calcining at 550 deg.C in air atmosphere for 10h to obtain TS-1 (60) -0.85 carrier with average size of 277nm as shown in FIGS. 1 (a), (d).
Taking 5mL of chloroauric acid aqueous solution with the concentration of 0.04867mol/L, adding 27mL of deionized water for dilution, adding 0.8g of the TS-1 molecular sieve carrier obtained above, and respectively using 1M and 0.1M Na 2 CO 3 And (2) adjusting the pH value of the solution adjusting system to be 7.9-8.0, stirring for 6h at 35 ℃, then performing suction filtration and washing, then drying for about 10h at 35 ℃ under vacuum, tabletting and sieving the obtained product for 20-40 meshes, and reducing 0.15g of the product for 2h at 300 ℃ in the atmosphere of hydrogen, propylene and nitrogen to obtain the Au/TS-1 (60) -0.85 catalyst.
Comparative example 1
2g of Tween 20 was mixed with 32g of deionized water at 40 ℃ in a three-neck flask, 18.8g of 40wt.% TPAOH aqueous solution was added and mixed at 40 ℃ for a while, and then 35.6g of TEOS was added and sufficiently stirred at 40 ℃ for hydrolysis.
Dissolving 0.97g of tetrabutyl titanate in 7.15g of isopropanol, uniformly mixing to obtain a titanium-containing solution, dropwise adding the titanium-containing solution into silica sol, starting to heat to 80 ℃ after dropwise adding, opening a three-mouth bottle stopper, and stirring at 80 ℃ to remove alcohol for 1h; and finally, filling the obtained solution into a crystallization kettle, crystallizing for 48 hours at 170 ℃, centrifugally washing a crystallized product until filtrate is neutral, drying overnight at 110 ℃, and roasting for 10 hours in air at 550 ℃ to obtain the TS-1 (60) -N carrier.
Taking 5mL of chloroauric acid aqueous solution with the concentration of 0.04867mol/L, adding 27mL of deionized water for dilution, adding 0.8g of the TS-1 molecular sieve carrier obtained above, and respectively using 1M and 0.1M Na 2 CO 3 And (2) adjusting the pH value of the solution adjusting system to be 7.9-8.0, stirring for 6h at 35 ℃, then performing suction filtration and washing, then drying for about 10h at 35 ℃ under vacuum, tabletting and sieving the obtained product for 20-40 meshes, and reducing 0.15g in hydrogen, propylene and nitrogen atmosphere at 300 ℃ for 2h to obtain the Au/TS-1 (60) -N catalyst.
Table 1 shows the product distribution and PO formation rate at 20h for the catalysts of examples 1-3 of the present invention and the catalyst of comparative example 1.
Reaction conditions C 3 H 6 /O 2 /H 2 /N 2 =1/1/1/7 (volume ratio), reaction temperature: 160 ℃, reaction pressure: 0.1MPa, space velocity: 14000mL h -1 g cat -1 All data are taken from the 20 th run after the reaction has run smoothly.
Claims (8)
1. A preparation method of micron Au/TS-1 catalyst for propylene gas phase epoxidation reaction under hydrogen-oxygen system is characterized by comprising the following steps:
(1) Dripping a titanium source into hydrochloric acid, adding deionized water, and stirring until the solution is clear; then adding a silicon source and continuously stirring for 30min to obtain a clear solution, wherein the molar ratio of each component is as follows: siO 2 2 :TiO 2 :H 2 O: HCl =1:0.0167-0.0333:20:0.067; the obtained solution is sprayed and dried by a spray drying deviceSpraying and drying to obtain titanium silicon amorphous powder A; conditions of the spray-drying apparatus: the temperature of the vaporization chamber is 180-300 ℃, and the feeding rate of the peristaltic pump is 7-20 mL/min -1 The frequency of the fan is 80Hz;
(2) Adding 25wt% or 40wt% of template agent aqueous solution and deionized water into the titanium silicon amorphous powder A, stirring to completely immerse the titanium silicon amorphous powder A into the template agent aqueous solution, wherein the molar ratio of each component of the final mixture is as follows: siO 2 2 :TiO 2 : template agent: h 2 O=1:(0.01-0.033):(0.05-0.1):(0.85-3.4);
(3) Putting the mixture obtained in the step (2) into a stainless steel crystallization kettle with a polytetrafluoroethylene lining, then putting the stainless steel crystallization kettle into a rotary oven for rolling crystallization at the temperature of 130-210 ℃, washing the mixture to be neutral by deionized water after crystallization for 24-72h, drying the mixture at the temperature of 90-110 ℃, and finally roasting the mixture at the temperature of 450-650 ℃ for 10h to remove a template agent to obtain a TS-1 molecular sieve;
(4) Taking the concentration as 7.6x10 -3 Adding the TS-1 molecular sieve carrier obtained in the step (3) into a mol/L chloroauric acid aqueous solution, wherein the mass ratio of the TS-1 molecular sieve carrier to the chloroauric acid is (9-10): 1, adjusting the pH value of a system to be 7.9-8.0, stirring for 6 hours at 35 ℃, performing suction filtration and washing, then drying for 10 hours at 35 ℃ in vacuum, tabletting and sieving the obtained product with 20-40 meshes, wherein the volume ratio is 1:1:7, reducing for 2 hours in a mixed atmosphere of hydrogen, propylene and nitrogen to prepare the Au/TS-1 catalyst.
2. The preparation method according to claim 1, wherein the calcination atmosphere in step (3) is one or a mixture of two or more of air, nitrogen, argon, helium and ammonia.
3. The method according to claim 1, wherein in the step (1), the stirring temperature is 25-40 ℃ and the stirring time is 2-12h; and (3) stirring at room temperature in the step (2).
4. The preparation method according to claim 1, wherein the template is one or a mixture of two or more of tetrapropylammonium hydroxide, tetrapropylammonium bromide, tetrapropylammonium chloride and tetrapropylammonium fluoride.
5. The method according to claim 1, wherein in step (1), the silicon source is one or a mixture of two or more of tetraethyl orthosilicate, tetramethyl orthosilicate, tetrapropyl orthosilicate and tetrabutyl orthosilicate, or one or a mixture of two or more of silica sol and silica white.
6. The preparation method according to claim 1, wherein the titanium silicalite molecular sieve has a silicon-titanium molar ratio of 30-100; the content of framework titanium is 1.3-4.2wt%; the substance mol ratio composition in the silicon-titanium amorphous powder A in the step (2) is SiO 2 :TiO 2 : template agent: h 2 O=1:0.0167-0.0333:0.05:0.85-3.4。
7. A catalyst prepared by the process of any one of claims 1 to 6.
8. Use of the catalyst of claim 7 in the preparation of propylene oxide by gas phase epoxidation of propene in the presence of a hydrogen and oxygen system, wherein the reaction is carried out in a fixed bed reactor at a temperature of from 80 to 300 ℃ and a volume ratio of the reaction gas composition C 3 H 6 /H 2 /O 2 /N 2 =1/1/1/7, and the space velocity is 4000-20000mL · h -1 ·Kg -1 cat.。
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