CN115999645A - Pickering emulsifier and preparation method and application thereof - Google Patents
Pickering emulsifier and preparation method and application thereof Download PDFInfo
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- CN115999645A CN115999645A CN202310023081.6A CN202310023081A CN115999645A CN 115999645 A CN115999645 A CN 115999645A CN 202310023081 A CN202310023081 A CN 202310023081A CN 115999645 A CN115999645 A CN 115999645A
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- 239000003995 emulsifying agent Substances 0.000 title claims abstract description 24
- 238000002360 preparation method Methods 0.000 title claims abstract description 8
- 239000002808 molecular sieve Substances 0.000 claims abstract description 98
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims abstract description 98
- UGACIEPFGXRWCH-UHFFFAOYSA-N [Si].[Ti] Chemical compound [Si].[Ti] UGACIEPFGXRWCH-UHFFFAOYSA-N 0.000 claims abstract description 65
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 claims abstract description 44
- HGCIXCUEYOPUTN-UHFFFAOYSA-N cyclohexene Chemical compound C1CCC=CC1 HGCIXCUEYOPUTN-UHFFFAOYSA-N 0.000 claims abstract description 44
- 230000002209 hydrophobic effect Effects 0.000 claims abstract description 36
- 238000006243 chemical reaction Methods 0.000 claims abstract description 28
- 239000000839 emulsion Substances 0.000 claims abstract description 18
- 238000006735 epoxidation reaction Methods 0.000 claims abstract description 13
- ZWAJLVLEBYIOTI-UHFFFAOYSA-N cyclohexene oxide Chemical compound C1CCCC2OC21 ZWAJLVLEBYIOTI-UHFFFAOYSA-N 0.000 claims abstract description 9
- FWFSEYBSWVRWGL-UHFFFAOYSA-N cyclohexene oxide Natural products O=C1CCCC=C1 FWFSEYBSWVRWGL-UHFFFAOYSA-N 0.000 claims abstract description 8
- 230000035484 reaction time Effects 0.000 claims abstract description 8
- 238000002425 crystallisation Methods 0.000 claims description 46
- 230000008025 crystallization Effects 0.000 claims description 46
- 238000003756 stirring Methods 0.000 claims description 45
- LPSKDVINWQNWFE-UHFFFAOYSA-M tetrapropylazanium;hydroxide Chemical compound [OH-].CCC[N+](CCC)(CCC)CCC LPSKDVINWQNWFE-UHFFFAOYSA-M 0.000 claims description 40
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims description 27
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 27
- 229910052719 titanium Inorganic materials 0.000 claims description 27
- 239000010936 titanium Substances 0.000 claims description 27
- 238000001035 drying Methods 0.000 claims description 23
- 238000005406 washing Methods 0.000 claims description 23
- 238000001354 calcination Methods 0.000 claims description 22
- 239000007788 liquid Substances 0.000 claims description 22
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 21
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 18
- 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 claims description 18
- 239000002243 precursor Substances 0.000 claims description 18
- 238000010438 heat treatment Methods 0.000 claims description 17
- 238000002156 mixing Methods 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 16
- PYJJCSYBSYXGQQ-UHFFFAOYSA-N trichloro(octadecyl)silane Chemical compound CCCCCCCCCCCCCCCCCC[Si](Cl)(Cl)Cl PYJJCSYBSYXGQQ-UHFFFAOYSA-N 0.000 claims description 14
- 239000006185 dispersion Substances 0.000 claims description 12
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 2
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 230000000630 rising effect Effects 0.000 claims description 2
- 239000002904 solvent Substances 0.000 abstract description 8
- 230000003197 catalytic effect Effects 0.000 abstract description 7
- 230000008901 benefit Effects 0.000 abstract description 4
- 238000000746 purification Methods 0.000 abstract description 3
- 238000011084 recovery Methods 0.000 abstract description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 2
- 238000000926 separation method Methods 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 53
- 230000000052 comparative effect Effects 0.000 description 15
- 239000007864 aqueous solution Substances 0.000 description 7
- 239000003054 catalyst Substances 0.000 description 6
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 6
- 239000012295 chemical reaction liquid Substances 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 239000012071 phase Substances 0.000 description 5
- 150000001336 alkenes Chemical class 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 4
- 238000001000 micrograph Methods 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 239000004593 Epoxy Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 230000002194 synthesizing effect Effects 0.000 description 2
- ZWAJLVLEBYIOTI-OLQVQODUSA-N (1s,6r)-7-oxabicyclo[4.1.0]heptane Chemical compound C1CCC[C@@H]2O[C@@H]21 ZWAJLVLEBYIOTI-OLQVQODUSA-N 0.000 description 1
- 239000008346 aqueous phase Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 238000004581 coalescence Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005216 hydrothermal crystallization Methods 0.000 description 1
- 238000002329 infrared spectrum Methods 0.000 description 1
- 230000016507 interphase Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000005501 phase interface Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000002444 silanisation Methods 0.000 description 1
- 238000006561 solvent free reaction Methods 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
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A40/00—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production
- Y02A40/90—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production in food processing or handling, e.g. food conservation
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- Silicates, Zeolites, And Molecular Sieves (AREA)
Abstract
The invention discloses a Pickering emulsifier and a preparation method and application thereof. The hydrophobic hollow titanium silicon molecular sieve is used as a Pickering emulsifying agent to construct stable Pickering emulsion for carrying out the epoxidation reaction of 1-hexene and cyclohexene, so that the conversion rate of 1-hexene and cyclohexene and the selectivity of the cyclohexene oxide and the cyclohexene oxide are successfully improved, and the reaction time is shortened. Meanwhile, the Pickering emulsion catalytic system is adopted to carry out the epoxidation reaction of 1-hexene and cyclohexene, no solvent is added, the problems of solvent recovery, product separation and purification and the like are effectively avoided, the production cost is reduced, and the economic benefit is increased.
Description
Technical Field
The invention relates to the field of Pickering emulsion catalysis, in particular to a Pickering emulsifier and a preparation method and application thereof.
Background
The green synthesis process for synthesizing the epoxy compound by catalyzing olefin in one step by using the titanium-silicon molecular sieve as a catalyst and using a hydrogen peroxide aqueous solution as an oxidant is an important green synthesis process for synthesizing the epoxy compound and is widely paid attention to researchers. Olefins such as 1-hexene, cyclohexene and the like are typical oil phases, aqueous hydrogen peroxide is typical aqueous phase, and the oil phase and the water phase are not mutually soluble, so acetonitrile and the like are usually required to be added as solvents to form a homogeneous reaction system so as to improve the olefin epoxidation reaction effect. However, the solvent reaction system has a plurality of problems such as solvent recovery, product purification and the like, and the energy consumption of the process of recovering the solvent by adopting the rectification operation is huge.
The Pickering emulsion catalytic system is a solvent-free reaction system based on stable Pickering emulsion, in the system, solid particles are adsorbed on an oil-water phase interface to form a compact particle film to stabilize dispersed phase liquid drops, and coalescence among the liquid drops is inhibited, so that macroscopic uniform mixing of oil-water phases is realized, and inter-phase transfer is enhanced. The Pickering emulsion catalytic system is introduced into olefin epoxidation reaction, so that the addition of an organic solvent can be effectively avoided, and the economic benefit of a reaction process is enhanced. For the pickering emulsion catalyst system, the solid particles have dual identities, one of which is pickering emulsifier and the other of which is pickering catalyst. For emulsifiers, the solid particles need to have moderate wettability; for catalysts, the solid particles need to have good diffusion properties.
Disclosure of Invention
The invention aims to: the invention aims to provide a hydrophobic hollow titanium silicon molecular sieve with moderate wettability and good diffusion performance as a Pickering emulsifier; the invention also aims to provide a preparation method and application of the Pickering emulsifier.
The technical scheme is as follows: the Pickering emulsifier is a hydrophobic hollow titanium-silicon molecular sieve with a hollow cavity of 10-100 nm, and the contact angle of the hydrophobic hollow titanium-silicon molecular sieve is 133.2-136.5 degrees.
The preparation method of the pickering emulsifier comprises the following steps:
(1) Dropwise adding tetraethyl silicate into tetrapropylammonium hydroxide solution, and stirring to obtain a transparent solution; tetrabutyl titanate is added into the transparent solution, and precursor liquid is obtained by stirring; and (3) placing the precursor liquid into a hydrothermal kettle for crystallization, centrifugally separating, washing, drying and calcining the product in the hydrothermal kettle to obtain the microporous titanium-silicon molecular sieve.
(2) And (3) stirring and mixing the obtained microporous titanium-silicon molecular sieve and tetrapropylammonium hydroxide solution, placing the mixture in a hydrothermal kettle for crystallization, centrifugally separating, washing, drying and calcining the product in the hydrothermal kettle to obtain the hollow titanium-silicon molecular sieve.
(3) Stirring and mixing the hollow titanium-silicon molecular sieve and the toluene solution of octadecyl trichlorosilane, performing heating reaction, centrifugally separating, washing and drying the product to obtain the hydrophobic hollow titanium-silicon molecular sieve, wherein the hydrophobic hollow titanium-silicon molecular sieve is the Pickering emulsifier.
Preferably, in the step (2), after the microporous titanium-silicon molecular sieve and the tetrapropylammonium hydroxide solution are stirred and mixed, the pre-reaction is required, the obtained pre-reaction solution is placed in a hydrothermal kettle for crystallization, and the product in the hydrothermal kettle is centrifugally separated, washed, dried and calcined to obtain the hollow titanium-silicon molecular sieve; wherein the pre-reaction temperature is 100-120 ℃, and the pre-reaction time is 2-12 h.
Further, in the step (1), the mass fraction of the tetrapropylammonium hydroxide solution is 20-25%, and the molar ratio of the tetrapropylammonium hydroxide to the tetraethyl silicate is 0.3:1-0.5:1; the molar ratio of tetrabutyl titanate to tetraethyl silicate is 0.03:1 to 0.05:1, a step of; the stirring temperature was from room temperature to 80 ℃.
Further, the crystallization temperature in the step (1) and the step (2) is 100-170 ℃, and the crystallization time is 24-96 hours; the calcination atmosphere is air or nitrogen, the calcination temperature is 500-550 ℃, the temperature rising rate is 2-3 ℃/min, and the calcination time is 6-10 h.
Further, in the step (2), the mass fraction of the tetrapropylammonium hydroxide solution is 20-25%, the tetrapropylammonium hydroxide concentration is 0.02-0.3M, and the mass ratio of the microporous titanium silicon molecular sieve to the tetrapropylammonium hydroxide solution is 1:10-1:30.
Further, in the step (3), the mass ratio of the hollow titanium silicon molecular sieve to the octadecyl trichlorosilane is 1:0.1-1:1, the reaction temperature is 60-90 ℃, and the reaction time is 6-10 hours.
The application of the Pickering emulsifier in the epoxidation of 1-hexene or cyclohexene.
The application of the Pickering emulsifier in the epoxidation of 1-hexene or cyclohexene comprises the following specific steps: dispersing a hydrophobic hollow titanium silicon molecular sieve in 1-hexene or cyclohexene to form a dispersion liquid, stirring the dispersion liquid and a 30% hydrogen peroxide aqueous solution at a high speed to obtain a stable Pickering emulsion, and heating to react; 1-hexene is correspondingly prepared into epoxyhexane; cyclohexene corresponds to the preparation of cyclohexene oxide.
Further, the mass ratio of the hydrophobic hollow titanium silicon molecular sieve to 1-hexene or cyclohexene is 1:1-1:10, the volume ratio of the dispersion liquid to 30% hydrogen peroxide aqueous solution is 1:1-4:1, the stirring speed is 8000-12000 r/min, the stirring time is 2-30 min, the reaction temperature is 60-100 ℃, and the reaction time is 2-10 h.
The beneficial effects are that: compared with the prior art, the invention has the following remarkable advantages: 1. the invention synthesizes the microporous titanium silicalite molecular sieve by adopting a hydrothermal crystallization method, performs pre-reaction and recrystallization operation on the microporous titanium silicalite molecular sieve to synthesize the hollow titanium silicalite molecular sieve, enhances the diffusion performance of the hollow titanium silicalite molecular sieve, and performs silanization modification on the hollow titanium silicalite molecular sieve to modify the wettability of the surface and the inside of a pore canal to synthesize the hydrophobic hollow titanium silicalite molecular sieve; 2. the invention uses a hydrophobic hollow titanium silicon molecular sieve as a Pickering emulsion emulsifier to construct a stable Pickering emulsion catalytic system, and carries out the epoxidation reaction of 1-hexene and cyclohexene, wherein the reaction temperature is 60 ℃ for 2 hours, the conversion rate of 1-hexene is more than 20.2%, and the selectivity of the cyclohexene oxide is 93.3%; the conversion rate of cyclohexene is above 9.1%, and the selectivity of cyclohexene oxide is above 75.5%. The conversion rate of 1-hexene and cyclohexene and the selectivity of the epoxyhexane and the epoxycyclohexane are successfully improved, and the reaction time is shortened; 3. the invention adopts the Pickering emulsion catalytic system to carry out the epoxidation reaction of 1-hexene and cyclohexene, does not add any solvent, effectively avoids the problems of solvent recovery, product separation and purification and the like, reduces the production cost and increases the economic benefit.
Drawings
Fig. 1 (a) is a transmission electron microscope image of a hydrophobic hollow titanium silicalite molecular sieve in example 1 of the present invention;
fig. 1 (b) is a transmission electron microscope image of the hydrophobic hollow titanium silicalite molecular sieve in example 2 of the present invention;
FIG. 1 (c) is a transmission electron microscope image of the hydrophobic hollow titanium silicalite molecular sieve in example 3 of the present invention;
fig. 1 (d) is a transmission electron microscope image of the hydrophobic hollow titanium silicalite molecular sieve in example 4 of the present invention;
FIG. 2 is an infrared spectrum of a hydrophobic hollow titanium silicalite molecular sieve according to examples 1, 2, 3 and 4 of the present invention;
fig. 3 (a) is a graph showing the contact angle of the hydrophobic hollow titanium silicalite molecular sieve according to example 1 of the present invention;
fig. 3 (b) is a graph showing the contact angle of the hydrophobic hollow titanium silicalite molecular sieve in example 2 of the present invention;
fig. 3 (c) is a graph of contact angle of hydrophobic hollow titanium silicalite molecular sieve in example 3 of the present invention;
fig. 3 (d) is a graph of contact angle of hydrophobic hollow titanium silicalite molecular sieve in example 4 of the present invention;
FIG. 4 (a) is a graph of droplets of a stable Pickering emulsion formed from the hydrophobic hollow titanium silicalite molecular sieve of example 1 of the present invention;
fig. 4 (b) is a diagram of droplets of a stable pickering emulsion formed by the hydrophobic hollow titanium silicalite molecular sieve of example 2 of the present invention;
FIG. 4 (c) is a graph of droplets of a stable Pickering emulsion formed by the hydrophobic hollow titanium silicalite molecular sieve of example 3 of the present invention;
fig. 4 (d) is a graph of droplets of a stable pickering emulsion formed by the hydrophobic hollow titanium silicalite molecular sieve of example 4 of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
Example 1
(1) Dropwise adding tetraethyl silicate into tetrapropylammonium hydroxide solution with the mass fraction of 25%, wherein the molar ratio of tetrapropylammonium hydroxide to tetraethyl silicate is 0.3:1, and stirring for 3 hours at room temperature to obtain a clear and transparent solution; adding tetrabutyl titanate into the transparent solution, wherein the molar ratio of the tetrabutyl titanate to the tetraethyl silicate is 0.025:1, and stirring for 2 hours at room temperature to obtain a precursor solution; the precursor liquid is placed in a hydrothermal kettle for crystallization, the crystallization temperature is 170 ℃, and the crystallization time is 48 hours; and separating, washing and drying the product in the hydrothermal kettle, and calcining in an air atmosphere at 550 ℃ at a heating rate of 2.5 ℃/min for 6 hours to obtain the microporous titanium-silicon molecular sieve.
(2) Stirring and mixing the obtained microporous titanium-silicon molecular sieve and 0.3M tetrapropylammonium hydroxide solution, and pre-reacting for 2 hours at 100 ℃ with the mass ratio of the microporous titanium-silicon molecular sieve to the 0.3M tetrapropylammonium hydroxide solution being 1:10; placing the obtained pre-reaction liquid into a hydrothermal kettle for crystallization, wherein the crystallization temperature is 170 ℃ and the crystallization time is 48 hours; and separating, washing and drying the product in the hydrothermal kettle, and calcining in an air atmosphere at 550 ℃ at a heating rate of 2.5 ℃/min for 6 hours to obtain the hollow titanium-silicon molecular sieve.
(3) Stirring and mixing the hollow titanium-silicon molecular sieve and the toluene solution of octadecyl trichlorosilane, reacting for 8 hours at 90 ℃ with the mass ratio of the hollow titanium-silicon molecular sieve to the octadecyl trichlorosilane being 1:0.2, centrifugally separating, washing and drying the product to obtain the hydrophobic hollow titanium-silicon molecular sieve.
Example 2
(1) Dropwise adding tetraethyl silicate into tetrapropylammonium hydroxide solution with the mass fraction of 25%, wherein the molar ratio of tetrapropylammonium hydroxide to tetraethyl silicate is 0.3:1, and stirring for 3 hours at room temperature to obtain a clear and transparent solution; adding tetrabutyl titanate into the transparent solution, wherein the molar ratio of the tetrabutyl titanate to the tetraethyl silicate is 0.025:1, and stirring for 2 hours at room temperature to obtain a precursor solution; the precursor liquid is placed in a hydrothermal kettle for crystallization, the crystallization temperature is 170 ℃, and the crystallization time is 48 hours; and separating, washing and drying the product in the hydrothermal kettle, and calcining in an air atmosphere at 550 ℃ at a heating rate of 2.5 ℃/min for 6 hours to obtain the microporous titanium-silicon molecular sieve.
(2) Stirring and mixing the obtained microporous titanium-silicon molecular sieve and 0.3M tetrapropylammonium hydroxide solution, and pre-reacting for 2 hours at 120 ℃ with the mass ratio of the microporous titanium-silicon molecular sieve to the 0.3M tetrapropylammonium hydroxide solution being 1:10; placing the obtained pre-reaction liquid into a hydrothermal kettle for crystallization, wherein the crystallization temperature is 170 ℃ and the crystallization time is 48 hours; and separating, washing and drying the product in the hydrothermal kettle, and calcining in an air atmosphere at 550 ℃ at a heating rate of 2.5 ℃/min for 6 hours to obtain the hollow titanium-silicon molecular sieve.
(3) Stirring and mixing the hollow titanium-silicon molecular sieve and the toluene solution of octadecyl trichlorosilane, reacting for 8 hours at 90 ℃ with the mass ratio of the hollow titanium-silicon molecular sieve to the octadecyl trichlorosilane being 1:0.2, centrifugally separating, washing and drying the product to obtain the hydrophobic hollow titanium-silicon molecular sieve.
Example 3
(1) Dropwise adding tetraethyl silicate into tetrapropylammonium hydroxide solution with the mass fraction of 25%, wherein the molar ratio of tetrapropylammonium hydroxide to tetraethyl silicate is 0.3:1, and stirring for 3 hours at room temperature to obtain a clear and transparent solution; adding tetrabutyl titanate into the transparent solution, wherein the molar ratio of the tetrabutyl titanate to the tetraethyl silicate is 0.025:1, and stirring for 2 hours at room temperature to obtain a precursor solution; the precursor liquid is placed in a hydrothermal kettle for crystallization, the crystallization temperature is 170 ℃, and the crystallization time is 48 hours; and separating, washing and drying the product in the hydrothermal kettle, and calcining in an air atmosphere at 550 ℃ at a heating rate of 2.5 ℃/min for 6 hours to obtain the microporous titanium-silicon molecular sieve.
(2) Stirring and mixing the obtained microporous titanium-silicon molecular sieve and 0.3M tetrapropylammonium hydroxide solution, and pre-reacting for 12 hours at 120 ℃ with the mass ratio of the microporous titanium-silicon molecular sieve to the 0.3M tetrapropylammonium hydroxide solution being 1:10; placing the obtained pre-reaction liquid into a hydrothermal kettle for crystallization, wherein the crystallization temperature is 170 ℃ and the crystallization time is 48 hours; and separating, washing and drying the product in the hydrothermal kettle, and calcining in an air atmosphere at 550 ℃ at a heating rate of 2.5 ℃/min for 6 hours to obtain the hollow titanium-silicon molecular sieve.
(3) Stirring and mixing the hollow titanium-silicon molecular sieve and the toluene solution of octadecyl trichlorosilane, reacting for 8 hours at 90 ℃ with the mass ratio of the hollow titanium-silicon molecular sieve to the octadecyl trichlorosilane being 1:0.2, centrifugally separating, washing and drying the product to obtain the hydrophobic hollow titanium-silicon molecular sieve.
Example 4
(1) Dropwise adding tetraethyl silicate into tetrapropylammonium hydroxide solution with the mass fraction of 25%, wherein the molar ratio of tetrapropylammonium hydroxide to tetraethyl silicate is 0.3:1, and stirring for 3 hours at room temperature to obtain a clear and transparent solution; adding tetrabutyl titanate into the transparent solution, wherein the molar ratio of the tetrabutyl titanate to the tetraethyl silicate is 0.025:1, and stirring for 2 hours at room temperature to obtain a precursor solution; the precursor liquid is placed in a hydrothermal kettle for crystallization, the crystallization temperature is 170 ℃, and the crystallization time is 48 hours; and separating, washing and drying the product in the hydrothermal kettle, and calcining in an air atmosphere at 550 ℃ at a heating rate of 2.5 ℃/min for 6 hours to obtain the microporous titanium-silicon molecular sieve.
(2) Stirring and mixing the obtained microporous titanium-silicon molecular sieve and 0.3M tetrapropylammonium hydroxide solution, wherein the mass ratio of the microporous titanium-silicon molecular sieve to the 0.3M tetrapropylammonium hydroxide solution is 1:10; placing the obtained reaction liquid into a hydrothermal kettle for crystallization, wherein the crystallization temperature is 170 ℃ and the crystallization time is 48 hours; and separating, washing and drying the product in the hydrothermal kettle, and calcining in an air atmosphere at 550 ℃ at a heating rate of 2.5 ℃/min for 6 hours to obtain the hollow titanium-silicon molecular sieve.
(3) Stirring and mixing the hollow titanium-silicon molecular sieve and the toluene solution of octadecyl trichlorosilane, reacting for 8 hours at 90 ℃ with the mass ratio of the hollow titanium-silicon molecular sieve to the octadecyl trichlorosilane being 1:0.2, centrifugally separating, washing and drying the product to obtain the hydrophobic hollow titanium-silicon molecular sieve.
Comparative example 1
Dropwise adding tetraethyl silicate into tetrapropylammonium hydroxide solution with the mass fraction of 25%, wherein the molar ratio of tetrapropylammonium hydroxide to tetraethyl silicate is 0.3:1, and stirring for 3 hours at room temperature to obtain a clear and transparent solution; adding tetrabutyl titanate into the transparent solution, wherein the molar ratio of the tetrabutyl titanate to the tetraethyl silicate is 0.025:1, and stirring for 2 hours at room temperature to obtain a precursor solution; the precursor liquid is placed in a hydrothermal kettle for crystallization, the crystallization temperature is 170 ℃, and the crystallization time is 48 hours; and separating, washing and drying the product in the hydrothermal kettle, and calcining in an air atmosphere at 550 ℃ at a heating rate of 2.5 ℃/min for 6 hours to obtain the microporous titanium-silicon molecular sieve.
Comparative example 2
(1) Dropwise adding tetraethyl silicate into tetrapropylammonium hydroxide solution with the mass fraction of 25%, wherein the molar ratio of tetrapropylammonium hydroxide to tetraethyl silicate is 0.3:1, and stirring for 3 hours at room temperature to obtain a clear and transparent solution; adding tetrabutyl titanate into the transparent solution, wherein the molar ratio of the tetrabutyl titanate to the tetraethyl silicate is 0.025:1, and stirring for 2 hours at room temperature to obtain a precursor solution; the precursor liquid is placed in a hydrothermal kettle for crystallization, the crystallization temperature is 170 ℃, and the crystallization time is 48 hours; and separating, washing and drying the product in the hydrothermal kettle, and calcining in an air atmosphere at 550 ℃ at a heating rate of 2.5 ℃/min for 6 hours to obtain the microporous titanium-silicon molecular sieve.
(2) Stirring and mixing the obtained microporous titanium-silicon molecular sieve and 0.3M tetrapropylammonium hydroxide solution, wherein the mass ratio of the microporous titanium-silicon molecular sieve to the 0.3M tetrapropylammonium hydroxide solution is 1:10; placing the obtained reaction liquid into a hydrothermal kettle for crystallization, wherein the crystallization temperature is 170 ℃ and the crystallization time is 48 hours; and separating, washing and drying the product in the hydrothermal kettle, and calcining in an air atmosphere at 550 ℃ at a heating rate of 2.5 ℃/min for 6 hours to obtain the hollow titanium-silicon molecular sieve.
Comparative example 3
(1) Dropwise adding tetraethyl silicate into tetrapropylammonium hydroxide solution with the mass fraction of 25%, wherein the molar ratio of tetrapropylammonium hydroxide to tetraethyl silicate is 0.3:1, and stirring for 3 hours at room temperature to obtain a clear and transparent solution; adding tetrabutyl titanate into the transparent solution, wherein the molar ratio of the tetrabutyl titanate to the tetraethyl silicate is 0.025:1, and stirring for 2 hours at room temperature to obtain a precursor solution; the precursor liquid is placed in a hydrothermal kettle for crystallization, the crystallization temperature is 170 ℃, and the crystallization time is 48 hours; and separating, washing and drying the product in the hydrothermal kettle, and calcining in an air atmosphere at 550 ℃ at a heating rate of 2.5 ℃/min for 6 hours to obtain the microporous titanium-silicon molecular sieve.
(2) Stirring and mixing the microporous titanium-silicon molecular sieve and a toluene solution of octadecyl trichlorosilane, reacting the hollow titanium-silicon molecular sieve and the octadecyl trichlorosilane for 8 hours at the temperature of 90 ℃ according to the mass ratio of 1:0.2, centrifugally separating, washing and drying the product to obtain the hydrophobic microporous titanium-silicon molecular sieve.
Test example 1
This test example is used to illustrate the reaction effect of the molecular sieve obtained by the method provided by the present invention and the molecular sieve obtained by the method of the comparative example for 1-hexene epoxidation.
The titanium silicalite molecular sieve samples prepared in the above examples and comparative examples were prepared as follows: the mass ratio of the 1-hexene is 1:5 stirring to prepare a dispersion liquid, mixing the dispersion liquid with 30% hydrogen peroxide aqueous solution, stirring for 30 minutes at a stirring rate of 12000 r/min to obtain Pickering emulsion, heating to 60 ℃ for 2h to prepare the epoxyhexane, and measuring the distribution of the obtained products on an Shimadzu GC-2014C chromatograph by using an OV-17 capillary column, wherein the volume ratio of the dispersion liquid to the hydrogen peroxide aqueous solution is 1:1, and the results are shown in Table 1.
Wherein:
TABLE 1
| Catalyst | Conversion of 1-hexene (%) | Hexane selectivity (%) |
| Example 1 | 23.3 | 96.3 |
| Example 2 | 21.8 | 95.4 |
| Example 3 | 20.2 | 93.3 |
| Example 4 | 10.6 | 88.5 |
| Comparative example 1 | 2.1 | 52.8 |
| Comparative example 2 | 4.6 | 70.9 |
| Comparative example 3 | 3.8 | 67.6 |
As can be seen from Table 1, the hydrophobic hollow titanium silicalite molecular sieve prepared by the method of the invention has high catalytic activity, and when the molecular sieve is used in 1-hexene epoxidation reaction, the 1-hexene conversion rate and the hexane oxide selectivity are obviously higher than those of the comparative example.
Test example 2
This test example is used to illustrate the reaction effect of the molecular sieve obtained by the method provided by the present invention and the molecular sieve obtained by the method of the comparative example for cyclohexene epoxidation.
The titanium silicalite molecular sieve samples prepared in the above examples and comparative examples were prepared as follows: the mass ratio of cyclohexene is 1:5 stirring to prepare a dispersion liquid, mixing the dispersion liquid with 30% hydrogen peroxide aqueous solution, stirring for 30 minutes at a stirring rate of 12000 r/min to obtain Pickering emulsion, heating to 60 ℃ for 2h to prepare the cyclohexene oxide, and measuring the distribution of the obtained products on an Shimadzu GC-2014C chromatograph by using an OV-17 capillary column, wherein the volume ratio of the dispersion liquid to the hydrogen peroxide aqueous solution is 1:1, and the results are shown in Table 2.
Wherein:
TABLE 2
| Catalyst | Cyclohexene conversion (%) | Cyclohexane oxide Selectivity (%) |
| Example 1 | 10.3 | 81.4 |
| Example 2 | 9.1 | 75.5 |
| Example 3 | 9.2 | 78.3 |
| Example 4 | 2.6 | 55.2 |
| Comparative example 1 | 0.3 | 22.6 |
| Comparative example 2 | 0.6 | 47.5 |
| Comparative example 3 | 0.4 | 38.7 |
As can be seen from Table 2, the hydrophobic hollow titanium silicalite molecular sieve prepared by the method of the invention has high catalytic activity, and when the molecular sieve is used in cyclohexene epoxidation reaction, the cyclohexene conversion rate and the cyclohexene oxide selectivity are obviously higher than those of the comparative example.
Claims (10)
1. The pickering emulsifying agent is characterized by being a hydrophobic hollow titanium silicalite molecular sieve with 10-100 nm hollow cavities, and the contact angle of the hydrophobic hollow titanium silicalite molecular sieve is 133.2-136.5 degrees.
2. The method for preparing the pickering emulsifier according to claim 1, comprising the following steps:
(1) Dropwise adding tetraethyl silicate into tetrapropylammonium hydroxide solution, and stirring to obtain a transparent solution; tetrabutyl titanate is added into the transparent solution, and precursor liquid is obtained by stirring; and (3) placing the precursor liquid into a hydrothermal kettle for crystallization, centrifugally separating, washing, drying and calcining the product in the hydrothermal kettle to obtain the microporous titanium-silicon molecular sieve.
(2) And (3) stirring and mixing the obtained microporous titanium-silicon molecular sieve and tetrapropylammonium hydroxide solution, placing the mixture in a hydrothermal kettle for crystallization, centrifugally separating, washing, drying and calcining the product in the hydrothermal kettle to obtain the hollow titanium-silicon molecular sieve.
(3) Stirring and mixing the hollow titanium-silicon molecular sieve and the toluene solution of octadecyl trichlorosilane, performing heating reaction, centrifugally separating, washing and drying the product to obtain the hydrophobic hollow titanium-silicon molecular sieve, wherein the hydrophobic hollow titanium-silicon molecular sieve is the Pickering emulsifier.
3. The method for preparing the pickering emulsifying agent according to claim 2, wherein in the step (2), after the microporous titanium-silicon molecular sieve and the tetrapropylammonium hydroxide solution are stirred and mixed, a pre-reaction is required, the obtained pre-reaction solution is placed in a hydrothermal kettle for crystallization, and a product in the hydrothermal kettle is centrifugally separated, washed, dried and calcined to obtain the hollow titanium-silicon molecular sieve; wherein the pre-reaction temperature is 100-120 ℃, and the pre-reaction time is 2-12 h.
4. The method for preparing the Pickering emulsifier according to claim 2, wherein in the step (1), the mass fraction of the tetrapropylammonium hydroxide solution is 20-25%, and the molar ratio of the tetrapropylammonium hydroxide to the tetraethyl silicate is 0.3:1-0.5:1; the mol ratio of tetrabutyl titanate to tetraethyl silicate is 0.03:1-0.05:1; the stirring temperature was from room temperature to 80 ℃.
5. The method for preparing pickering emulsifying agent according to claim 2, wherein the crystallization temperature in step (1) and step (2) is 100-170 ℃ and the crystallization time is 24-96 hours; the calcination atmosphere is air or nitrogen, the calcination temperature is 500-550 ℃, the temperature rising rate is 2-3 ℃/min, and the calcination time is 6-10 h.
6. The method for preparing the Pickering emulsifier according to claim 2, wherein in the step (2), the mass fraction of the tetrapropylammonium hydroxide solution is 20-25%, the concentration of tetrapropylammonium hydroxide is 0.02-0.3M, and the mass ratio of the microporous titanium-silicon molecular sieve to the tetrapropylammonium hydroxide solution is 1:10-1:30.
7. The method for preparing the pickering emulsifying agent according to claim 2, wherein in the step (3), the mass ratio of the hollow titanium silicon molecular sieve to the octadecyl trichlorosilane is 1:0.1-1:1, the reaction temperature is 60-90 ℃, and the reaction time is 6-10 hours.
8. Use of the pickering emulsifier of claims 1-7 in 1-hexene or cyclohexene epoxidation reactions.
9. The use according to claim 8, wherein hydrophobic hollow titanium silicalite molecular sieve is dispersed in 1-hexene or cyclohexene to form a dispersion, and the dispersion is stirred with 30% aqueous hydrogen peroxide solution at high speed to obtain stable pickering emulsion, and the temperature is raised for reaction; 1-hexene is correspondingly prepared into epoxyhexane; cyclohexene corresponds to the preparation of cyclohexene oxide.
10. The use according to claim 8, wherein the mass ratio of the hydrophobic hollow titanium silicalite molecular sieve to 1-hexene or cyclohexene is 1:1-1:10, the volume ratio of the dispersion to 30% aqueous hydrogen peroxide solution is 1:1-4:1, the stirring rate is 8000-12000 rpm, the stirring time is 2-30 minutes, the reaction temperature is 60-100 ℃, and the reaction time is 2-10 hours.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20120277468A1 (en) * | 2011-04-27 | 2012-11-01 | China Petrochemical Development Corporation, Taipei (Taiwan) | Titanium-silicalite molecular sieve, method for preparing the same and method for preparing cyclohexanone oxime using the molecular sieve |
| CN104874419A (en) * | 2015-05-20 | 2015-09-02 | 天津大学 | Titanium silicalite molecular sieve catalyst and application of titanium silicalite molecular sieve in cyclohexanone ammoximation |
| CN114082441A (en) * | 2021-11-23 | 2022-02-25 | 江苏科技大学 | MFI molecular sieve and preparation method and application thereof |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20120277468A1 (en) * | 2011-04-27 | 2012-11-01 | China Petrochemical Development Corporation, Taipei (Taiwan) | Titanium-silicalite molecular sieve, method for preparing the same and method for preparing cyclohexanone oxime using the molecular sieve |
| CN104874419A (en) * | 2015-05-20 | 2015-09-02 | 天津大学 | Titanium silicalite molecular sieve catalyst and application of titanium silicalite molecular sieve in cyclohexanone ammoximation |
| CN114082441A (en) * | 2021-11-23 | 2022-02-25 | 江苏科技大学 | MFI molecular sieve and preparation method and application thereof |
Non-Patent Citations (1)
| Title |
|---|
| GUOJUN LV ET AL.，: "Hydrophobized hollow TS-1 zeolite as pickering interfacial catalyst for selective oxidation reactions", 《COLLOIDS AND SURFACES A: PHYSICOCHEMICAL AND ENGINEERING ASPECTS》, vol. 633, 2 November 2021 (2021-11-02) * |
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