A kind of preparation method of high flux molecular screen membrane
Technical field
The application is related to a kind of preparation method of ceramic membrane, and more particularly to one kind is with hydrophily and with high-throughout point
The preparation method of sub- sieve membrane.
Background technology
Organic solvent plays very important effect in modern industry, all available for medicine, chemical industry, material, metallurgy etc.
It is multi-field.In some application scenarios, the purity requirement to organic solvent is harsher, such as requires that organic solvent purity exists
More than 99.99%, and water is one of dopant type common in organic solvent, because it dissolves each other with some organic solvents, therefore it is de-
Water seems particularly significant in product purification.
In existing dehydration of organic solvent technique, infiltration evaporation is a kind of ideal technique, and it has, and energy consumption is low, work
Many advantages, such as skill is simple.And for infiltration evaporation technique, infiltrating and vaporizing membrane is the key factor in infiltration evaporation technique.
And existing infiltrating and vaporizing membrane includes organic film and the class of inoranic membrane two substantially, and molecular screen membrane is common inorganic infiltrating and vaporizing membrane
Type, because the features such as its Stability Analysis of Structures receives many concerns.
The molecular screen membrane type that organic solvent osmotic, evaporating and dewatering can be used in the prior art mainly has NaA, NaY, ZSM-
5th, T, CHA, MOR, Sapo-34, DDR etc. are a variety of, and the Si/Al of wherein ZSM-5 molecular sieve film ZSM-5 type molecular screen membranes compares model
Enclose wide(10~∞)With the pore passage structure of prosperity(0.55nm × 0.51nm Z fonts duct and 0.53nm × 0.56nm's
Linear pattern duct)As good osmotic, evaporating and dewatering membrane material, but also due to the intimate total silicon of its skeleton structure is not hydrophilic,
Therefore flux is smaller, constrains its industrial applications.Therefore, it is badly in need of a kind of improvement hydrophilic method of ZSM-5 molecular sieve film.
The content of the invention
To improve the water flux of molecular screen membrane, the invention provides a kind of preparation method of high flux molecular screen membrane.
Technical scheme is as follows:
A kind of preparation method of high flux molecular screen membrane, ZSM-5 molecular sieve film is synthesized using secondary growth method on porous support,
And continue do not have separation function using secondary growth method synthesis on ZSM-5 molecular sieve film after removed template method is calcined
NaA molecular sieve layer, and control the crystallization time of NaA molecular sieve layer to be less than 1h.Preferably, the casting solution of NaA molecular sieve layer is prepared
Including Na2O, SiO2, NaOH and water, its mol ratio is 50:5:1:2400, its crystallization time is 20-40min.
Because NaA molecular sieve has low silica alumina ratio compared with ZSM-5 molecular sieve, therefore it has a stronger hydrophily, and it
So selection NaA rather than other kinds of hydrophilic molecule sieve, this is due to be found through experiments that compared to other kinds of parent
Water-based sieve particle, NaA easily grow in ZSM-5 film layers.Based on the characteristic, Integral Thought of the invention is in ZSM-
The outer surface of 5 molecular screen membranes synthesizes one layer of NaA molecular sieve layer, and why call it as NaA molecular sieve layer rather than NaA film layers
Because the layer does not have separation function, and only hydrophilic to improve its by modifying one layer of NaA molecular sieve outside ZSM-5 molecular sieve film
Performance, and control by the controlling crystallizing time thickness of NaA molecular sieve layer.But NaA layers are modified outside film layer, although changing
It is apt to its hydrophilicity, but the increase of thicknesses of layers have impact on the flux of film in turn again, based on this, it is contemplated that secondary growth method
Stronger to the controllability of crystal growth, we select secondary growth method crystallization NaA molecular sieve layer, are found by contrast experiment, when
When crystallization time is less than 1h.
Preferably, use on porous support secondary growth method synthesis ZSM-5 molecular sieve film used by crystal seed for
One or both of ZSM-5 molecular sieve, Silicalite-1 molecular sieves.Preferably, coat on porous support first during crystal seed
Using 1 μm of > of vacuum suction coating bulky grain crystal seed, then the little particle crystal seed using leaching Tu method coating 400-600nm.
In the prior art, synthesis ZSM-5 molecular sieve film typically uses ZSM-5 molecular sieve particle, also has part document to use
The Silicalite-1 molecular sieves of MFI configurations are belonged to ZSM-5.But in experiments it is found that, when mixing uses two kinds of molecules
When sieve is used as crystal seed, its is better.And for coating method, we are selected using bulky grain molecular sieve as coating crystal seed first
To cover the macropore of more empty carriers, continue after the drying be coated with little particle crystal seed in case little particle crystal seed enter carrier hole in shadow
Flux is rung, existing crystal seed coating method has that infusion process, swabbing process, vacuum aspiration, Electrostatic Absorption method etc. are a variety of, and passes through pair
The contrast of single coating method and multiple combinations coating method, it has been found that when optimal by the way of vacuum suction+leaching Tu.And
It is optimal by the way of vacuum suction+leaching Tu.When preparing crystal seed, using common hydrothermal crystallizing prepare ZSM-5 molecular sieve and
Silicalite-1 molecular sieves generally be more than 1 μm, and use microwave heating prepare ZSM-5 molecular sieve and
Silicalite-1 molecular sieves are generally less than 1 μm, average out to 300nm or so, and mechanical lapping or ball milling have been used in document
Mode, which handles crystal seed, reduces its particle diameter, its little particle crystal seed that can be applied equally in the present invention.And in multiple combinations,
Our preferred Silicalite-1 molecular sieves make bulky grain crystal seed, and for ZSM-5 molecular sieve as little particle crystal seed, this is due to ZSM-
5 have and than Silicalite-1 more preferably induce performance, and can avoid carrier using Silicalite-1 as bulky grain crystal seed
In element such as Al be doped into skeleton structure so as to influence crystallization process.
Preferably, use secondary growth method prepare NaA molecular sieve layer used by crystal seed for 200-2000nm NaA molecules
Sieve.Here, the NaA molecular sieve using 200-500nm can be selected, can also select to use the NaA molecules more than 500nm
Sieve.It is well known that preparing ZSM-5 molecular sieve film needs by high-temperature calcination process, easily there is crack in film layer at high temperature.For
This, when using crystal seed less than 500nm, little particle crystal seed be easily accessible crystallization in defective hole and in water-heat process so as to
Physically block the crack.Certainly, the NaA molecular sieve duct for blocking the crack is more than ZSM-5 ducts, to a certain extent can shadow
Ring the separation of overall film layer, but due to influence degree and little, can ignore.The molecular sieve for preparing the particle size range can
To select the molecular sieve of Hydrothermal Synthesiss(The sieve particle particle diameter prepared under different condition differs, generally more than 1 μm)Machine
Tool crushes, such as grinding, rod milling, ball milling etc..It can also select to use microwave-hydrothermal method, NaA molecular sieve particle prepared by the method
It is generally individually smaller than 500nm.And found through experiment, using little particle crystal seed, the preferred 20-40min of crystallization time, further preferably 30min
When its flux it is optimal.Alternatively, it is also possible to select to use the molecular sieve more than 500nm as crystal seed, the crystal seed phase of the particle size range
To being difficult to enter in crack, but other method can be selected to block defective hole, such as ZSM-5 molecular sieve film is being placed in NaA
Before in casting solution, ZSM-5 molecular sieve film is placed in cyclodextrin aqueous solution, 30s is aspirated using vacuum aspiration, and after the drying
Continuation stands 2-6h in cyclodextrin aqueous solution, and 1-3h is dried at 60-100 DEG C.Lacked so that cyclodextrin gel enters to have
The defects of falling into the film in hole therefrom and blocks the hole.Due in ZSM-5 molecular sieve film layer additional NaA molecular sieve layer again, because
This liquid in application process(Including organic solvent and water)The defective hole can not be directly contacted, avoids the extensive of defective hole
It is multiple.Concretely comprise the following steps before described ZSM-5 molecular sieve film is placed in NaA casting solutions, ZSM-5 molecular sieve film is placed in ring paste
2-6h is stood in the smart aqueous solution, and 1-3h is dried at 60-100 DEG C.And use this method prepare the optimal crystallization time of film for
40-60min, preferably 50min.
Preferably, described baking modes are baking inphases, and actual conditions is:The frequency that heated up during -200 DEG C of room temperature is 2 DEG C/
The frequency that heated up when min, 200-400 DEG C is 1 DEG C/min, is 0.5 DEG C/min at 400-450 DEG C, 2-4h, 450- are maintained at 450 DEG C
The frequency that cools at 200 DEG C is 1 DEG C/min, and 200- room temperatures are 2 DEG C/min.In ZSM-5 molecular sieve film application process, film layer occurs
Easily there is crack(Defective hole)It is lax usual, it has impact on the industrial applications of such molecular screen membrane.Known references pair
It is calcined to produce crack and have selected in film and keeps away and look for second solution, i.e., using the film is prepared without template machine method, is taken off so as to avoid template
The possibility in crack is produced during removing.But preparing ZSM-5 molecular sieve film using Template-free method method has extremely strict system
Standby condition and relatively low lumber recovery, even if laboratory also successfully is difficult to test industrial applications.And in the present invention, synthesize ZSM-
The mode that 5 molecular screen membranes employ template+secondary growth method synthesizes, and synthesis condition is simple, and repetitive rate is high.But for roasting
The problem of producing crack, for the present invention by the way of being calcined stage by stage, which can alleviate film defective hole to a certain extent
Producing, heating frequency is 2 DEG C/min when concrete mode is -200 DEG C of room temperature, and the frequency that heats up at 200-400 DEG C is 1 DEG C/min,
It is 0.5 DEG C/min at 400-450 DEG C, maintains 2-4h at 450 DEG C, cooling frequency is 1 DEG C/min at 450-200 DEG C, 200- room temperatures
For 2 DEG C/min.The Integral Thought of above-mentioned baking modes is to use heating mode as fast as possible at low temperature, and when close roasting
During temperature, programming rate slows down as far as possible, from the generation for avoiding fast programming rate from causing defective hole.
Preferably, described porous carrier type is tubular type, hollow fiber form, and material is aluminum oxide, zirconium oxide, YSZ, oxygen
Change titanium or metal.
The present invention compares compared with the prior art, has advantages below:
1. present invention additional NaA molecular sieve layer outside traditional ZSM-5 molecular sieve film layer, and pass through the controlling crystallizing time
The hydrophily of film is greatly improved, so as to add the water flux of film.
2. by regulating and controlling the painting method of film, the performance of film is improved, by regulating and controlling baking modes, reduces film defect
Probability caused by hole, and entered by the contact of the NaA molecular sieve particle with small particle and hydrothermal crystallizing NaA in defective hole
With influence of the hole to film layer that supply a gap.
Inevitably, when one layer of NaA molecular sieve layer of ZSM-5 molecular sieve film outer cladding in total silicon, overall steady of film
Qualitative certainty weakens due to the cladding of NaA molecular sieve layer, but because NaA molecular sieve layer is relatively thin, resistance to overturning is influenceed
It is not very big.But in actual application, if the effect of solvent, the layer of NaA molecular sieve containing aluminium is it is possible that certain
Molten brilliant phenomenon so as to cause hydrophilicity to weaken, now when being unsatisfactory for application conditions, film layer can be immersed to NaA casting films again
Modified in liquid.
Brief description of the drawings
The present invention is further described in conjunction with the accompanying drawings and embodiments:
Fig. 1 is the water flux of molecular screen membrane and the relation of crystallization time prepared using the method for the embodiment of the present invention 1.
Fig. 2 is the water flux of molecular screen membrane and the relation of crystallization time prepared using the method for the embodiment of the present invention 2.
Embodiment
This specification is described further with specific embodiment below in conjunction with the accompanying drawings:
It is further details of explanation to the present invention presently in connection with drawings and examples.The accompanying drawing is simplified schematic diagram, only with
Illustration illustrates the essential structure of the present invention, therefore it only shows the composition relevant with the present invention.
Embodiment 1
The Silicalite-1 sieve particles that bulky grain is prepared first with in-situ synthesis and microwave process for synthesizing (are surveyed through particle diameter
Try 1.5 μm of average grain diameter) and short grained ZSM-5 molecular sieve particle (testing average grain diameter 500nm through particle diameter), and prepare respectively
The crystal seed liquid of 2wt.% concentration.Meanwhile using microwave attenuation materials NaA molecular sieve(Average grain diameter 400nm), and be equally made
The crystal seed liquid of 2wt.% concentration.
The Alpha-alumina tubular porous carrier of purchase is closed through the latter end seal of pre-treatment, other end vacuum suction bulky grain
Silicalite-1 molecular sieve seed liquid(Vacuum 0.09MPa, suction time 30s)And dry, continue to coat using infusion process
Short grained ZSM-5 molecular sieve crystal seed liquid(40s), and drying for standby.
Produce ZSM-5 casting solutions, by TPAOH (TPABr), aluminum oxide, silica, sodium oxide molybdena, sodium chloride and
Water is mixed, and casting solution is prepared into through being stirred vigorously(Gel), its mol ratio is followed successively by 1:84:10:100:3500:10.
Porous carrier is placed in the reactor containing casting solution, the crystallization 36h at 150 DEG C.After washing and drying is handled,
It is placed under high temperature and is calcined, calcination procedure is:Heating frequency be 2 DEG C/min during -200 DEG C of room temperature, and the frequency that heats up at 200-400 DEG C is
It is 0.5 DEG C/min at 1 DEG C/min, 400-450 DEG C, maintains 2-4h at 450 DEG C, the frequency that cools at 450-200 DEG C is 1 DEG C/min,
200- room temperatures are 2 DEG C/min.
NaA molecular sieve Synthesis liquid is produced, quantitative Na2O, Ludox, sodium hydroxide and water are mixed, and stirs so that
N (Na2O) in Synthesis liquid:N (Ludox):(Sodium hydroxide):N (water)=50:5:1:2400.And crystal seed liquid will be coated with
ZSM-5 molecular sieve film is placed in one, the crystallization under 80 DEG C of hydrothermal conditions.
By molecular screen membrane prepared by embodiment 1 in the case where feeding temperature is 60 DEG C, ethanol mass concentration is in ethanol/water system
Infiltration evaporation experiment is carried out in 50% feed liquid, the characterize data under its different crystallization time is as shown in figure 1, in crystallization time 0-
Separation change is little in 120min, maintains essentially in 1500-1800 or so, but the change of crest formula is presented in water flux, when
When crystallization time is 20-40min, particularly 30min or so, water flux basically reaches peak, is 1.8Kg/ (m3*h).
Embodiment 2:
The Silicalite-1 sieve particles that bulky grain is prepared first with in-situ synthesis and microwave process for synthesizing (are surveyed through particle diameter
Try 1.5 μm of average grain diameter) and short grained ZSM-5 molecular sieve particle (testing average grain diameter 500nm through particle diameter), and prepare respectively
The crystal seed liquid of 2wt.% concentration.Meanwhile using Hydrothermal Synthesiss NaA molecular sieve(1.8 μm of average grain diameter), and it is dense that 2wt.% is equally made
The crystal seed liquid of degree.
The Alpha-alumina tubular porous carrier of purchase is closed through the latter end seal of pre-treatment, other end vacuum suction bulky grain
Silicalite-1 molecular sieve seed liquid(Vacuum 0.09MPa, suction time 30s)And dry, continue to coat using infusion process
Short grained ZSM-5 molecular sieve crystal seed liquid(40s), and drying for standby.
Produce ZSM-5 casting solutions, by TPAOH (TPABr), aluminum oxide, silica, sodium oxide molybdena, sodium chloride and
Water is mixed, and casting solution is prepared into through being stirred vigorously(Gel), its mol ratio is followed successively by 1:84:10:100:3500:10.
Porous carrier is placed in the reactor containing casting solution, the crystallization 36h at 150 DEG C.After washing and drying is handled,
It is placed under high temperature and is calcined, calcination procedure is:Heating frequency be 2 DEG C/min during -200 DEG C of room temperature, and the frequency that heats up at 200-400 DEG C is
It is 0.5 DEG C/min at 1 DEG C/min, 400-450 DEG C, maintains 2-4h at 450 DEG C, the frequency that cools at 450-200 DEG C is 1 DEG C/min,
200- room temperatures are 2 DEG C/min.
The cyclodextrin aqueous solution that concentration is 5% is prepared, by the ZSM-5 molecular sieve film submergence of preparation wherein, one end sealing, is adopted
30s is aspirated with vacuum aspiration, and continues to stand 2h in cyclodextrin aqueous solution after drying 10min at 60 DEG C, and at 100 DEG C
Lower dry 1h.
By ZSM-5 molecular sieve film after pre-treatment, NaA molecular sieve crystal seed liquid, coating time are coated using infusion process
30s, coating twice, and are dried.
NaA molecular sieve Synthesis liquid is produced, quantitative Na2O, Ludox, sodium hydroxide and water are mixed, and is stirred,
So that n (Na2O) in Synthesis liquid:N (Ludox):(Sodium hydroxide):N (water)=50:5:1:2400.And crystal seed liquid will be coated with
ZSM-5 molecular sieve film be placed in one, the crystallization under 80 DEG C of hydrothermal conditions.
By molecular screen membrane prepared by embodiment 2 in the case where feeding temperature is 60 DEG C, ethanol mass concentration is in ethanol/water system
Infiltration evaporation experiment is carried out in 50% feed liquid, the characterize data under its different crystallization time is as shown in Fig. 2 in crystallization time 0-
In 120min, separation change is little, maintains essentially in 1500-1800 or so, but the change of crest formula is presented in water flux, when
When crystallization time is 40-60min, particularly 50min or so, water flux basically reaches peak, is 1.8Kg/ (m3*h).
Highly preferred embodiment of the present invention is the foregoing is only, is not intended to limit the invention.It is all the present invention principle and
Any modification, equivalent substitution and improvements done within spirit etc., should be included within the scope of the present invention.