KR20080078294A - A preparation method of metallic nano porous membranes - Google Patents

Abstract

A metallic membrane is provided to improve pore size of the metallic membrane and improve physical properties such as strength, chemical stability, etc. of a polymer membrane at the same time, and a preparation method of the metallic membrane is provided. A preparation method of a metallic nano porous membrane comprises: a first process of dispersing powder particles of transition metals of third and fourth periods and alloys thereof into a polar solvent to prepare a first formed body; a second process of coating the first formed body with 1 to 10 wt.% of powder particles having a particle size of 5 to 30 nm of transition metals of third and fourth periods and alloys thereof to prepare a precursor; and a third process of sintering the precusor in a temperature range of 500 to 700 deg.C under an atmosphere of a mixture of nitrogen and hydrogen to prepare a membrane. The powder particles of transition metals of third and fourth periods and alloys thereof are selected from nickel, titanium, aluminum, copper, iron, and stainless steel. The polar solvent is selected from N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, and dimethyl sulfoxide. The nitrogen and hydrogen are used at a volume ratio of 70 to 98:2 to 30. The metallic membrane has a pore size of 30 to 60 nm and a porosity of 20 to 30%.

Description

A preparation method of metallic nano porous membranes

FIG. 1 shows the surface of a nickel hollow fiber membrane separator formed by the first embodiment of the present invention through an electron microscope.

Figure 2 shows the surface of the nanoporous metal hollow fiber membrane prepared according to the nanoporous metal separator and the method of manufacturing the present invention through an electron microscope.

The present invention relates to a method for producing a metal separator having nano-level pores, and in more detail, three- and four-cycle transition metals having a specific particle diameter, alloy powders thereof and synthetic polymers are dissolved at a constant ratio, and then The primary molded body is manufactured by the method of preparing a membrane, and the precursor is formed by coating an alloy particle powder having a small particle size on the manufactured primary molded body, and then sintered at a specific temperature of a mixed gas atmosphere of nitrogen and hydrogen. The present invention relates to a nanoporous metal separator and a method of manufacturing the same.

In general, polymer hollow fiber membranes have a weak tensile strength and thus have a high risk of cutting, and when membrane contamination occurs, it is difficult to recover permeate flow rate by a backwashing method. In addition, there is a risk that the pores are collapsed by high backwash pressure, and in the case of chemical washing, there was a problem in changing the form and physical properties of the pores.

On the other hand, polymer hollow fiber membranes are not high in temperature resistance and cannot be used for high temperature treatment materials. In the case of reinforcement-reinforced hollow fiber membranes without risk of cutting, the polymer membrane coating layer is formed from reinforcement materials when backwashed by a backwash method. There was a problem that peeled off and could not use. In the case of improving the conventional problem, the ceramic separator may overcome some of the disadvantages of the polymer separator, but the use of the ceramic separator is extremely limited due to the problem of cracking during use.

In addition, in the case of metal separation membranes, the pore size is formed in the range of 0.1 to 10 μm when primarily molded by the sintering method. There was a problem.

Accordingly, the present invention has been invented in view of the above-described conventional problems, and a first object of the present invention is to improve the diameter size of the metal separator and to improve the properties of the polymer membrane, such as strength and chemical stability. To provide.

The second object of the present invention is to produce a metal separation membrane having improved mechanical / chemical properties by spinning, polymer oxidizing and sintering a specific transition metal and alloy particle powder and synthetic polymer thereof, and using a metal particle powder having a small particle size. It is to provide a method for producing a metal separator coated on the separator.

In the production method according to the object of the present invention, by dispersing the three-cycle and four-cycle transition metals and their alloy particle powder in a polar solvent to prepare a primary molded body, the particle size is 5 ~ 30nm on the primary molded body A precursor is prepared by coating 3 to 4 cycle transition metals and 1 to 10% by weight of their alloy particle powder, and the precursor is sintered at a temperature in the range of 500 to 700 ° C. under an atmosphere in which nitrogen and hydrogen are mixed.

The metal separator prepared by the manufacturing method may be implemented as a metal separator in the form of a hollow fiber membrane or a flat membrane and a capillary membrane for easy implementation by those skilled in the art.

The above objects and other objects, advantages and features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate preferred embodiments.

Hereinafter will be described in more detail through an embodiment of the present invention.

The present invention dissolves 50 to 90% by weight of a three-cycle transition metal and an alloy particle powder thereof having a particle size of 0.01 to 20 µm, and 5 to 15% by weight of a synthetic polymer in a polar solvent, followed by spinning or casting to form a membrane precursor. After the preparation, the membrane precursor is oxidized to a polymer in the temperature range of 400 ~ 700 ℃ under a mixed gas atmosphere of nitrogen and hydrogen, the separator precursor oxidized the polymer is sintered at 900 ~ 1300 ℃ temperature range of nitrogen and hydrogen 1 A tea molded body is manufactured. Here, the method of manufacturing the primary molded body is an example of manufacturing a metal separator, and may be modified by various other methods of preparing a metal separator for a person skilled in the art to easily perform the method.

After coating the primary molded body produced by the above production method with a small three-cycle and four-cycle alloy particle powder having a particle size of 5 ~ 30nm, 500 ~ 700 ℃ temperature range under a mixed gas atmosphere of nitrogen and hydrogen It consists of a manufacturing method that reduces the pore size by sintering at.

As described in more detail the nano-porous metal separator of the present invention and a method of manufacturing the same, first, the three-cycle and four-cycle transition metals and their alloy particle powder is dispersed by circulating in a high-speed disperser without using a dispersant in an organic solution Prepare a coating solution. Here, the three- and four-cycle transition metals and their alloy particle powders are specifically nickel (Ni), titanium (Ti), aluminum (Al), copper (Cu), iron (Fe), stainless steel (Stainless steel) As the selected metal powder and mixed powder thereof, in the present invention, the pore size can be uniformly formed due to the uniform particle size of the metal with high resistance to oxidation, and it is more preferable to use nickel having a low unit cost of the metal produced. desirable.

On the other hand, when the particle size of the metal powder is less than 5 nm, the unit cost of the metal powder is high, and the economic efficiency is low, and the sintering property is poor, and there is no nanoporous property, and there is no significant difference from the primary molded body before coating. It is preferable to maintain the above range because the size is formed to 1㎛ or more to generate pores of the size unsuitable for use in water treatment.

The 3 and 4 cycle transition metals and their alloy particle powders are used in an amount of 1 to 10% by weight. If the amount is less than 1% by weight, the density of the particle powders contained in the primary molded body is small and the pore distribution is increased to 10% by weight. In the case of exceeding the thickness of the coating on the primary molded body becomes large, the primary molded body and the coating layer is separated, so the problem occurs that the coating is not made it is preferable to maintain the above range.

On the other hand, the solvent for dispersing the three-cycle and four-cycle transition metals and their alloy particle powder is to use a polar solvent that dissolves the polymer when preparing the primary molded body, more specifically N-methyl-2- It is selected from pyrrolidone, dimethylformamide, dimethylacetamide, and dimethyl sulfoxide. At this time, the solution is preferably maintained in the range of 90 to 99% by weight.

Next, the metal particles coated on the primary molded body are sintered to manufacture a metal separator having nano-level pores, which is performed by maintaining a mixed gas atmosphere of nitrogen and hydrogen during sintering. The volume ratio of nitrogen and hydrogen is 70 to 98: 2 to 30 (nitrogen: hydrogen).

Such a volume ratio of nitrogen and hydrogen is oxidized at a high temperature when the volume ratio of hydrogen is less than 2%, oxidizes to the primary molded body, and brittle occurs. When hydrogen exceeds 30%, a hydrogen explosion occurs at a high temperature. It is not possible to maintain this range because it is impossible.

Such a mixed gas is used at a speed of 10 to 2000 cc / min / unit, and if the speed is less than 10 cc / min / unit, some oxidation occurs to cause brittleness, and if it exceeds 2000 cc / min / unit, the consumption rate of the mixed gas is exceeded. It is preferable to carry out within the above range because the economic efficiency is low. At this time, the sintering temperature is maintained in the range of 500 ~ 700 ℃, if the sintering temperature is less than 500 ℃ sintering does not occur sufficiently, the coating layer is peeled off, if it exceeds 700 ℃ sintering excessively occurs, there is a problem that pores are not formed As it occurs, the above range is maintained.

The metal separation membrane manufactured through this manufacturing method may be manufactured in the form of a hollow fiber membrane, a flat membrane, or a capillary membrane to facilitate a person skilled in the art.

Hereinafter will be described in more detail through an embodiment of the present invention.

<First Embodiment>

Dispersions are prepared to prepare the polymer / metal precursors in hollow fiber form.

A dispersion made of 7% by weight of polysulfone, 28% by weight of N-methyl-2-pyrrolidone (NMP), and 65% by weight of nickel powder having a size of 3 µm was prepared, and then injected into a spinning nozzle having a diameter of 1.5 mm to obtain a hollow solution. After spinning in the form of sand, it is solidified in distilled water. Thereafter, the precursor was immersed in water for one day to remove through exchange of solvent and water, the polymer was oxidized in a high temperature combustion furnace, and the metal particles were sintered under nitrogen / hydrogen atmosphere.

The mixed gas flow rate is 250cc / min / unit, and it is maintained at 600 ℃ at the rate of 5 ℃ / min and maintained for 2 hours under the air atmosphere. After oxidizing the polymer material, it is maintained at 1150 ℃ at the rate of 10 ℃ / min for 2 hours. To complete the sintering and cooled to 10 ° C / min.

The nickel hollow fiber separator prepared above had a diameter of 1 mm, a thickness of 0.1 mm, a pore size of 1 to 4 μm, and a porosity of about 30%.

The first embodiment is a method of manufacturing a metal separator for manufacturing a primary molded body for manufacturing a nano-porous metal separator of the present invention.

Second Embodiment

To coat the metal powder on the primary molded body prepared in Example 1, 5 wt% of nickel powder having a size of 20 nm was added to NMP, mixed with a high speed disperser, and completely dispersed. After impregnating the primary molded body in the dispersed nickel mixture, the polar solvent is volatilized in an oven at 100 ° C. After sintering the metal particles in a nitrogen / hydrogen atmosphere in a high temperature combustion furnace, the mixture gas flow rate was 250cc / min / unit, and the temperature was raised to 700 ° C at 5 ° C / min ascending rate and maintained for 2 hours. Cool to 10 ° C / min.

It was confirmed that the hollow fiber separator prepared through the second embodiment has a pore size of 60 nm and a porosity of approximately 20%.

Third Embodiment

A nickel hollow fiber membrane was prepared in the same manner as in the second embodiment, after removing the excess coating solution on the surface of the primary molded body impregnated in the prepared nickel mixture solution.

It was confirmed that the hollow fiber separator prepared through the third embodiment has a pore size of 50 nm and a porosity of approximately 25%.

Fourth Embodiment

In the same manner as in the second embodiment, the primary molded body is manufactured in the form of a bundle using an epoxy adhesive, and connected to a suction pump to force a suction of the nickel mixture into the pores of the primary molded body, and the liquid overcoated on the surface. By completely removing the nickel particles were allowed to sinter only in the pores.

The hollow fiber separator prepared through the fourth embodiment was found to have a pore size of 50 nm and a porosity of approximately 25%.

<Fifth Embodiment>

In the same manner as in the second embodiment, only the nickel particles, not the nickel mixture solution, were forcibly inserted into the primary molded body to increase the density of the nickel particles in the pores to prepare a metal separator.

It was confirmed that the hollow fiber separator prepared through the fifth embodiment had a pore size of 30 nm and a porosity of approximately 20%.

Sixth Embodiment

In the same manner as in the first embodiment, the metal separator was prepared by varying the type of metal powder as follows. The pore size and porosity of the metal separator prepared above are shown in Table 1 below.

TABLE 1

 Type of metal powder  Pore size (nm)  Porosity (%)  titanium  80  30  aluminum  100  40  Copper  60  10  Stainless steel  100  30

As shown in Table 1, it can be seen that the pore size is larger than nickel and the porosity is low depending on the type of metal.

Therefore, it was confirmed that the nickel metal is more excellent in the metal powder.

The mechanical and chemical properties of the nanoporous metal hollow fiber membranes prepared through Examples 1 to 6 were measured by the following method, and the results are shown.

[How to measure]

1. Tensile strength: measuring the strength when cut by pulling with a constant force in the longitudinal direction;

2. Impact strength: Determination of breaking strength by applying impact with constant force in the length and vertical direction;

3. Back washing strength: Filling water into membrane to increase pressure to measure breaking strength;

4. Chemical stability: Tensile strength measurement after 24 hours immersion in 10% by weight of HCl and NaOH;

TABLE 2

 division  Tensile Strength (Kg / fiber)  Impact Strength (Kg / fiber)  Backwash Strength (Kg)  Chemical Stability (Kg / fiber)  First embodiment  70,000  25  42  60,000  Second embodiment  73,000  25  44  65,000  Third embodiment  75,000  26  44  68,000  Fourth embodiment  78,000  26  45  68,000  Fifth Embodiment  83,000  30  47  71,000

As shown in Table 2, when the sintering is completed, the nanoporous metal hollow fiber separator prepared according to the present invention has mechanical properties such as tensile strength, impact strength, backwash strength, etc., compared to the hollow fiber separator without coating. It can be seen that it is possible to maintain the degree of improvement and improved chemical stability.

Embodiments of the present invention as described above are shown as an example, and may be modified and modified under various conditions in order to facilitate those skilled in the art.

By using the nanoporous metal separation membrane of the present invention configured and acting as described above and a method of manufacturing the same, a metal separation membrane having improved physical properties such as strength and chemical stability of the polymer membrane can be prepared while improving the diameter size of the metal separation membrane. It has an effect.

In addition, the pore size of the prepared metal separator is 30 ~ 60nm, the porosity is 20 ~ 30%, and can be produced a metal separator with improved mechanical properties and chemical stability, such as tensile strength, impact strength and backwash strength It works.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it will be readily apparent to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the present invention. Are all within the scope of the appended claims.

Claims (6)

A first step of dispersing three- and four-cycle transition metals and their alloy particle powders in a polar solvent to produce a primary molded body; A second step of preparing a precursor by coating 3 to 4 cycle transition metals having a particle size of 5 to 30 nm and 1 to 10 weight percent of alloy powders thereof on the primary molded body; And a third process of sintering the precursor in a temperature range of 500 to 700 ° C. under a mixed atmosphere of nitrogen and hydrogen, to prepare a separator. The method of claim 1, The three- and four-cycle transition metals and their alloy particle powder is selected from nickel, titanium, aluminum, copper, iron and stainless steel. The method of claim 1, The polar solvent is N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide and dimethyl sulfoxide method for producing a nano-porous metal separation membrane, characterized in that selected from. The method of claim 1, The method of manufacturing a nano-porous metal separation membrane, characterized in that the ratio of nitrogen and hydrogen is used in a volume ratio of 70 to 98: 2 to 30 (nitrogen: hydrogen). The method of claim 1, The metal separator has a pore size of 30 to 60 nm, porosity of 20 to 30% of the method for producing a nano-porous metal separator. The method according to any one of claims 1 to 5, Nanoporous metal separation membrane, characterized in that produced by any one of the hollow fiber membrane or flat membrane and capillary membrane through the manufacturing method.

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