A kind of method of synthesizing molecular screen membrane from in-site aging-microwave heat
Technical field:
The present invention relates to the synthetic of molecular screen membrane and use, a kind of novel method of quick synthesizing molecular sieve film particularly is provided: original position is aging-and microwave heating is synthetic.
Background technology:
Since nearly half a century, along with energy starved aggravation and people's environmental consciousness strengthen day by day, traditional high energy consumption, high pollution industry are badly in need of carrying out large-scale technological improvement.Membrane separation technique since its compare with the isolation technique in the traditional industry and have less energy-consumption, do not produce pollutions, advantage such as be easy to realize to separate continuously, be easy to be coupled, can under mild conditions, realize separating, being easy to amplify and obtain more and more widely application at industrial sectors such as chemical industry, food, medicine, environmental protection, metallurgy with other sepn process.Zeolite molecular sieve film is a kind of novel inorganic film that grows up nearest more than ten years, advantage such as it has, and general mineral membrane is high temperature resistant, chemical resistance of concrete and biological attack, physical strength height, flux are big.Simultaneously, it has the constructional feature of zeolite molecular sieve again: the pore passage structure of rule possesses the molecule sieve performance; Specific surface area is big, high adsorption capacity; But the parent/hydrophobicity of modulation.These characteristics make zeolite molecular sieve film have good separation performance, and making it has wide application prospect in many membrane process (as infiltration evaporation, gas film separation, film reaction etc.).In addition, because on zeolite molecules sieve structure and the performance, zeolite molecular sieve film has also shown extremely strong application prospect in various fields such as host-guest chemistry, chromatogram, life science, electrode, transmitter, optical material, electricity materials.
In recent years, the scientist of lot of domestic and foreign has carried out extensive studies to the synthetic and application of molecular screen membrane, developed the synthetic method of multiple molecular screen membrane, mainly comprised: original position hydrothermal synthesis method (not needing the precoating crystal seed), diauxic growth (crystal seed method) method, gas phase synthesis method etc.Wherein for gas phase synthesis method, because the molecular screen membrane that this method synthesizes is difficult to guarantee the conversion fully of its gel, and when generating molecular sieve, several molecular sieves can form simultaneously, are unfavorable for the stable of molecular screen membrane.Synthetic for the original position hydro-thermal, its advantage is simple to operate, and is widely applicable, but because its original position nucleation and the surface properties of carrier and the micro of synthetic liquid have much relations, so the synthetic poor repeatability.Owing to there be not being pre-existing in of crystal seed, taking place easily in the synthetic process changes brilliant in addition.For the diauxic growth method, carrier surface has added crystal seed in advance, thereby accelerated the formation of molecular screen membrane, and restrained and changeed brilliant generation, but with the prerequisite that this method synthesizes high performance molecular screen membrane is to obtain uniform precoating crystal seed layer, otherwise the space of crystal seed layer will cause the formation of the defective of the molecular screen membrane that synthesizes.Another weak point operation of this method is more loaded down with trivial details, and is not suitable for complex-shaped carrier.
From at the end of last century, the synthetic of molecular screen membrane is one of research focus of countries in the world academia, industry member always, and the many relevant patents and the report of document are arranged.Professor Kita of Japan Yamaguchi university has synthesized the A type molecular sieve film from gelling system at the porous alumina basement membrane, they are applied to the synthetic molecular screen membrane in organism/water infiltration evaporation separation, shown good performance (day disclosure laid-open patent JP 08,318,141).But because the synthetic method that they adopt is the diauxic growth method, synthetic membrane surface before needs precoating crystal seed, complicated operation; Simultaneously, be the great gelling system of viscosity because they adopt, be the synthetic of carrier so be not suitable for tubular fibre, hyperchannel pottery etc.World patent PCT/GB95/0221 adopts settled solution as synthetic liquid, has synthesized the A type molecular sieve film scribbling on the porous metal basement membrane of crystal seed.Before not doing synthetic aftertreatment, molecular screen membrane is to the separation factor of water/aqueous isopropanol of 8.8wt.% not 13.5, and saturating amount is 3.2Kg/m
2.hr, the result is not very desirable.Professor Budd of Britain Manchester university adopts the settled solution prescription equally, and 0 original position has been synthesized the A type molecular sieve film on porous zirconium white/Ni-Cr alloy network basement membrane.The synthesis condition that they adopt is 50 ℃, 48 hours.They will synthesize molecular screen membrane be applied to alcohol/water infiltration evaporation and separate, the separation factor of isopropanol is 1000-10000, measures at 0.5kg/m thoroughly
2.hr (select from Microporous Materials, vol.12,1997, p305), but their method is to the having relatively high expectations of carrier (alumina supporter is because its cost is low, is the carrier of the most frequent use), and generated time is also longer.
In addition, amplification during for industrial application is synthetic, increasing along with used synthesis reactor, all demand side is to such as the scale-up problems such as sedimentation phenomenon under thermograde that occurs in the heat transfer process and the influence of gravity for above method, and also to be why molecular screen membrane has passed through the research of more than ten years but seldom can realize one of industrialized reason so far for this.
Because microwave heating is a kind of body heat phase, and microwave heating can shorten generated time greatly, and therefore in microwave is synthetic, thermograde that occurs in the conventional heat transfer process and the scale-up problems such as sedimentation phenomenon under the influence of gravity will be readily solved.Chinese patent 99112751.X number, adopt settled solution, with the synthetic A type molecular sieve film of the method for microwave heating, but their method need (provide embodiment by the precoating crystal seed in the patent on carrier, under the situation that does not have the precoating crystal seed, do not synthesize the successive molecular screen membrane), this has just limited their application of method on the complicated shape carrier.
If can make full use of the characteristics of microwave heating,, then be expected to synthesize quickly and efficiently high performance molecular screen membrane with actual application value in conjunction with original position synthetic advantage.
Summary of the invention:
The object of the present invention is to provide a kind of novel method of synthesizing molecular sieve film: original position is aging-and microwave heating is synthetic.The molecular screen membrane that this method synthesizes has high separation performance, and synthetic have high repeatability, and need be at carrier surface precoating crystal seed, and this synthetic method can be applied to various complex carriers.
Particularly, the invention provides a kind of method of synthesizing molecular screen membrane from in-site aging-microwave heat, it is characterized in that preparation process is as follows:
(1) preparation of the synthetic liquid of molecular sieve, the mol ratio prescription is: aNa
2O: Al
2O
3: bSiO
2: cH
2O, a=20~70, b=3~300, c=500~4000;
(2) the porous basement membrane is placed synthetic liquid, carry out original position together with synthetic liquid and wear out before microwave heating, aging temperature is 30 ℃~100 ℃, and digestion time is 3~10 hours;
(3) after aging, utilize microwave heating synthetic, temperature is 50 ℃~100 ℃, and generated time is 10~60 minutes;
(4) washing and drying.
Wherein with a=40~70, b=5~250, c=1000~3500 are good.
The basement membrane of synthesizing molecular sieve film provided by the invention is porous oxide basement membrane or porous metal film, and basal lamina material is an aluminum oxide, silicon oxide, zirconium white, stainless steel; The shape of basement membrane can be sheet, tubulose, tubular fibre, hyperchannel ceramic monolith.
In the method for synthesizing molecular screen membrane from in-site aging-microwave heat of the present invention, original position is aging can be adopted conventional heating or adopt microwave heating.Original position aged temperature is preferably lower than microwave heating synthetic temperature.
The preparation method of synthesizing molecular sieve film provided by the invention does not need carrier precoating crystal seed, and is easy and simple to handle, widely applicable.
The preparation method of synthesizing molecular sieve film provided by the invention after aging, only needs a microwave heating Synthetic 2 just obtain the successive molecular screen membrane in 5 minutes, and generated time routine adds process for thermosynthesizing and shortened a lot.
Synthetic A type molecular sieve film of the present invention has shown outstanding alcohol/water infiltration evaporation performance, and uses method provided by the invention to synthesize, and synthetic repeatability is quite high.
Description of drawings:
Accompanying drawing 1 is the preparation flow synoptic diagram of molecular screen membrane;
Accompanying drawing 2 is the x-ray diffraction pattern of embodiment 1 synthesizing molecular sieve film;
Accompanying drawing 3 is the scanning electron microscope diagram of embodiment 1 synthesizing molecular sieve film;
Accompanying drawing 4 is the scanning electron microscope diagram of embodiment 2 synthesizing molecular sieve films;
Accompanying drawing 5 is the x-ray diffraction pattern of embodiment 4 synthesizing molecular sieve films;
Accompanying drawing 6 is the x-ray diffraction pattern of embodiment 5 synthesizing molecular sieve films;
Accompanying drawing 7 is the scanning electron microscope diagram of embodiment 5 synthesizing molecular sieve films;
Accompanying drawing 8 is the x-ray diffraction pattern of comparative example 1 synthesizing molecular sieve film;
Accompanying drawing 9 is the scanning electron microscope diagram of comparative example 1 synthesizing molecular sieve film;
Accompanying drawing 10 is the x-ray diffraction pattern of comparative example 2 synthesizing molecular sieve films;
Accompanying drawing 11 is the scanning electron microscope diagram of comparative example 2 synthesizing molecular sieve films;
Accompanying drawing 12 is the x-ray diffraction pattern of comparative example 3 synthesizing molecular sieve films;
Accompanying drawing 13 is the scanning electron microscope diagram of comparative example 3 synthesizing molecular sieve films.
Embodiment:
The preparation of embodiment 1A type molecular screen membrane
The used basement membrane of synthesizing molecular sieve film is a porous Al
2O
3Basement membrane, its aperture are 0.1-0.3um, and voidage is 30%, and basement membrane is shaped as sheet, and diameter is 25mm, and thickness is 2mm.Basement membrane polishes flat ultrasonic washing in the distilled water, dry for standby then before using with spun yarn paper.Basement membrane after the oven dry does not need the precoating crystal seed, is directly used in synthetic.
The preparation flow synoptic diagram as shown in Figure 1.
The synthetic liquid of synthesizing molecular sieve film disposes as follows:
Solution (1): 100.0 gram NaOH are dissolved in the 398ml deionized water, add 2.5 gram metal aluminum foils then, and dissolving promptly gets solution (1);
Solution (2): 82.3 gram NaOH are dissolved in the 398ml deionized water, add the 46.3ml silicon sol then and (wherein contain SiO
2Be 26%, density is 1.16g/ml), dissolving promptly gets solution (2);
Wait to join solution (1) and solution (2) afterwards, with the two mixing, promptly get evenly clarifying synthetic liquid, the mol ratio prescription of the synthetic liquid that finally obtains is: 50Na
2O: Al
2O
3: 5SiO
2: 1000H
2O.
The diaphragm that is not coated with crystal seed is fixed with support, vertically be positioned in the tetrafluoroethylene synthesis reactor, will synthesize liquid and change among the synthesis reactor; Before microwave is synthetic, synthesis reactor is placed 50 ℃ of baking ovens, make diaphragm original position under synthetic liquid existence condition wear out 7 hours; After aging, synthesis reactor is placed microwave oven, within 60 seconds, be warming up to 90 ℃ rapidly, reduce microwave power then, keep synthetic liquid temp, reacted 25 minutes at 90 ℃; To neutral, spend the night then by 100 ℃ of oven for drying through deionized water wash for diaphragm after synthetic.Repeat aforesaid operations twice, the molecular screen membrane that obtains is A type molecular sieve film (as shown in Figure 2) through the X-ray diffraction levies in kind.Membrane surface has the even and fine and close molecular screen membrane of one deck to form (as shown in Figure 3) as can be seen from the electron scanning micrograph.
The preparation of embodiment 2A type molecular screen membrane
Press embodiment 1 identical operations, be the basement membrane that is adopted be tubulose, internal diameter is 10mm, external diameter is 14mm, length is 40cm.The film pipe two ends that are not coated with crystal seed are blocked (preventing the synthetic liquid of the inner contact of film pipe) with the tetrafluoroethylene plug, vertically be positioned over then in the tetrafluoroethylene synthesis reactor, synthesize at the outside surface of film pipe.The surface topography that can see the molecular screen membrane that synthesizes from electron scanning micrograph is the molecular screen membrane similar (as shown in Figure 4) that carrier synthesizes with the sheet basement membrane in embodiment 1.
The preparation of embodiment 3A type molecular screen membrane
Press embodiment 2 identical operations, the film pipe outer wall that just will not be coated with crystal seed is wrapped with (preventing the synthetic liquid of film pipe outer wall contact) with teflin tape, vertically is positioned over then in the tetrafluoroethylene synthesis reactor, synthesizes at the internal surface of film pipe.The Pervaporation Separation of the molecular screen membrane of synthetic gained synthetic molecular screen membrane outside pipe is approaching.This example explanation adopts this method to synthesize in the duct of carrier easily, therefore goes for hyperchannel carrier and tubular fibre.
The preparation of embodiment 4MOR type molecular screen membrane
The synthetic liquid of synthesizing molecular sieve film disposes as follows:
Solution (1): 52.3 gram NaOH are dissolved in the 190ml deionized water, add 5.2 gram sodium aluminate (42%Na then
2O, 54%Al
2O
3), dissolving promptly gets solution (1);
Measure the 477.5ml silicon sol and (wherein contain SiO
2Be 26%, density is 1.16g/ml) under agitation condition, be added dropwise in the solution (1), promptly obtain the synthetic liquid of milk shape, the mol ratio prescription of the synthetic liquid that finally obtains is: 66.7Na
2O: Al
2O
3: 240SiO
2: 3333.3H
2O.
The diaphragm that is not coated with crystal seed is fixed with support, vertically be positioned in the tetrafluoroethylene synthesis reactor, will synthesize liquid then and change among the synthesis reactor; Before microwave is synthetic, synthesis reactor is placed 90 ℃ of baking ovens, make diaphragm original position under synthetic liquid existence condition wear out 8 hours; After aging, synthesis reactor is placed microwave oven, within 70 seconds, be warming up to 140 ℃ rapidly, reduce microwave power then, keep synthetic liquid temp, reacted 30 minutes at 140 ℃; To neutral, spend the night then by 100 ℃ of oven for drying through deionized water wash for diaphragm after synthetic.Repeat aforesaid operations twice, the molecular screen membrane that obtains is a MOR type molecular sieve structure (as shown in Figure 5) through the X-ray diffraction levies in kind.
The preparation of embodiment 5FAU type molecular screen membrane
The synthetic liquid of synthesizing molecular sieve film disposes as follows:
Solution (1): 15.0 gram NaOH are dissolved in the 340ml deionized water, add 0.54 gram metal aluminum foil then, and dissolving promptly gets solution (1);
Solution (2): 25 gram NaOH are dissolved in the 150ml deionized water, add the 20ml silicon sol then and (wherein contain SiO
2Be 26%), dissolving promptly gets solution (2);
Wait to join solution (1) and solution (2) afterwards, with the two mixing, promptly get evenly clarifying synthetic liquid, the mol ratio prescription of the synthetic liquid that finally obtains is: 50Na
2O: Al
2O
3: 10SiO
2: 2870H
2O.
The diaphragm that is not coated with crystal seed is fixed with support, vertically be positioned in the tetrafluoroethylene synthesis reactor, will synthesize liquid then and change among the synthesis reactor; Before microwave is synthetic, synthesis reactor is placed 60 ℃ of baking ovens, make diaphragm original position under synthetic liquid existence condition wear out 6 hours; After aging, synthesis reactor is placed microwave oven, within 60 seconds, be warming up to 100 ℃ rapidly, reduce microwave power then, keep synthetic liquid temp, reacted 20 minutes at 100 ℃; To neutral, spend the night then by 100 ℃ of oven for drying through deionized water wash for diaphragm after synthetic.Repeat aforesaid operations twice, the molecular screen membrane that obtains is a FAU type molecular sieve structure (as shown in Figure 6) through the X-ray diffraction levies in kind.Membrane surface has formed continuously molecular screen membrane (as shown in Figure 7) uniformly as can be seen from the electron scanning micrograph.
The infiltration gasification separation performance of embodiment 6 molecular screen membranes
The molecular screen membrane of embodiment 3 gained is carried out the infiltration evaporation Separation Research, when the infiltration temperature is 65 ℃, as shown in table 1 to the separating resulting of different alcohol/aqueous systems:
The Pervaporation Separation of table 1 molecular screen membrane
System | Methanol | Ethanol/water | Isopropanol | Glycol/water |
Stock liquid dense (wt.%) | 90% | 90% | 90% | 50% |
Separation factor | 480 | 10000 | 10000 | 10000 |
Saturating amount (g/m
2.hr)
| 410 | 520 | 960 | 1870 |
By table as seen, the A type molecular sieve film that synthesizes by method provided by the invention has outstanding alcohol/water sepn performance.
Embodiment 7 molecular screen membrane synthetic repeated experiments
Adopt the tubulose basement membrane, length is 8cm, synthesizes according to the method for embodiment 3, carries out 5 parallel tests altogether.The film pipe of synthetic gained carries out the infiltration evaporation separating experiment, and the infiltration temperature is 65 ℃, and stock liquid is the ethanol/water system of 90wt.%.All are as a result shown in the table 2:
Table 2 molecular screen membrane synthetic repeated experiment
The experiment sequence number | Separation factor | Saturating amount (g/m
2.hr)
|
1 | 10000 | 510 |
2 | 10000 | 500 |
3 | 4500 | 580 |
4 | 2200 | 580 |
5 | 10000 | 520 |
By table as seen, adopt method synthesizing molecular sieve film provided by the invention to have good repeatability.
Comparative example 1
(1) preparation of A type molecular sieve film
Press embodiment 1 identical operations, just before microwave is synthetic, that diaphragm original position under synthetic liquid existence condition is not aging, but directly synthesis reactor is placed microwave oven, within 100 seconds, be warming up to 90 ℃ rapidly, reduce microwave power then, keep synthetic liquid temp, reacted 25 minutes at 90 ℃; To neutral, spend the night then by 100 ℃ of oven for drying through deionized water wash for diaphragm after synthetic.Repeat twice of aforesaid operations.The molecular screen membrane that obtains characterizes through X-ray diffraction and finds that membrane surface does not have the appearance (as shown in Figure 8) of tangible molecular sieve diffraction peak.Membrane surface does not have molecular screen membrane and forms (as shown in Figure 9) as can be seen from the electron scanning micrograph.
Comparative example 2
(2) preparation of A type molecular sieve film
Press embodiment 1 identical operations, just digestion time is extended to 12 hours.Molecular screen membrane warp-the X-ray diffraction that obtains turns out to be A type molecular sieve film (as shown in figure 10), but the infiltration evaporation that is applied to ethanol/water separates, and the result who obtains is very poor, and selecting coefficient is 131, and saturating amount is 590g/m
2.hr.By long owing to digestion time as can be seen on the scanning electronic microscope, the growth of molecular screen membrane therebetween begins, and the homogeneous nucleation when causing microwave synthetic is suppressed, thereby fails to obtain high performance molecular screen membrane (as shown in figure 11).
Comparative example 3
(3) preparation of A type molecular sieve film
Pressing embodiment 1 identical operations, is to 60min with microwave synthetic time lengthening.Molecular screen membrane warp-the X-ray diffraction that obtains characterizes to be found, it is brilliant that the molecular screen membrane that membrane surface forms has taken place to change, and gone out A type molecular sieve film diffraction peak, also has the appearance (as shown in figure 12) of the diffraction peak of hydroxysodalite.The infiltration evaporation that is applied to ethanol/water separates, and the result who obtains is very poor, and selecting coefficient is 3, and saturating amount is 1600g/m
2.hr.By long owing to the microwave generated time as can be seen on the scanning electronic microscope, molecular screen membrane is partly dissolved, and changes brilliant (as shown in figure 13).