KR20200035595A - Ceramic membrane and method for preparing same - Google Patents

Abstract

The present invention relates to a ceramic membrane comprising only a support and a separation layer, and a manufacturing method thereof. The membrane filtration throughput can be increased.

Description

Ceramic membrane and its manufacturing method {CERAMIC MEMBRANE AND METHOD FOR PREPARING SAME}

The present invention relates to a ceramic film and its manufacturing method.

With the development of the industry, the harmful effects of harmful substances such as dust, soot, waste gas, smoke, and volatile organic chemicals (VOC's) generated in each industrial process are increasing. Therefore, in order to prevent the release of these pollutants, some polymer filters are used, but in the case of polymer filters, there are problems in heat resistance, chemical resistance, abrasion resistance and flame retardancy.

Therefore, ceramic filters have been developed to solve these problems. Ceramic filters have much better heat resistance, chemical resistance, and abrasion resistance than polymer filters. There is no need to save the installation cost and maintenance cost.

The existing ceramic membrane is composed of a three-layer structure of a support-intermediate layer-separation layer. The reasons for the presence of the intermediate layer are as follows. When the separation layer is dip-coated without an intermediate layer on the lag, the pore size of the support is larger than the particles forming the separation layer, and the separation layer particles penetrate all into the pores of the support to block the pores of the support and the separation layer is not formed. Because it is not. Therefore, an intermediate layer composed of medium-sized particles is coated on a support having the largest particles, and a separation layer composed of the smallest particles is coated thereon.

Korean Patent Publication No. 10-2010-0001482

An object of the present invention is to provide a ceramic film and a method of manufacturing the same.

One embodiment of the present invention, the step of filling at least a portion of the pores of the porous support with solid particles; Forming a separation layer on the porous support filled with the solid particles; And it provides a method for producing a ceramic membrane comprising the step of removing the solid particles from the porous support.

Another embodiment of the present invention, a porous support; It provides a ceramic membrane made of a separation layer formed on the porous support, prepared according to the method of manufacturing a ceramic membrane of the present invention.

The method of manufacturing a ceramic membrane according to an exemplary embodiment of the present invention is to prepare a ceramic membrane composed of only a support and a separation layer without an intermediate layer by infiltrating certain solid particles into the support, thereby reducing process time and process cost, and by the manufacturing method. The prepared ceramic membrane has an advantage of increasing the membrane filtration throughput by reducing the total permeation resistance because there is no intermediate layer.

1 illustrates a method of manufacturing a ceramic film according to an exemplary embodiment of the present invention.
2 is an SEM image of a porous support according to an exemplary embodiment of the present invention.
3 is an SEM image after forming and firing a separation layer on a porous support according to a comparative example of the present invention.
4 is a SEM image before filling and firing carbon black according to an exemplary embodiment of the present invention on a porous support.
5 is a SEM image after filling a porous support with carbon black according to an exemplary embodiment of the present invention, and forming and separating a separation layer.
6 is a SEM image after filling graphite in a porous support according to an exemplary embodiment of the present invention, forming a separation layer, and firing.
7 is a SEM image before filling and firing a carbon nanotube in a porous support according to an exemplary embodiment of the present invention.
8 is a SEM image after filling a porous support with a nanotube according to an exemplary embodiment of the present invention, forming a separation layer, and firing.

In the present invention, when a part is said to “include” a certain component, it means that the component may further include other components, not to exclude other components, unless otherwise stated.

Hereinafter, preferred embodiments of the present invention will be described. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

One embodiment of the present invention comprises the steps of filling at least a portion of the pores of the porous support with solid particles; Forming a separation layer on the porous support filled with the solid particles; And it provides a method for producing a ceramic membrane comprising the step of removing the solid particles from the porous support. The particles of the separation layer in which the solid particles are smaller than the pores of the porous support are prevented from penetrating into the pores of the porous support, so that a separation layer can be formed without forming an intermediate layer on the porous support. Since a lot of energy and cost are consumed in the formation of the intermediate layer, the present invention can reduce it, thereby reducing the process time and cost. In addition, by filling without a solvent, there is an advantage in the process, there is an advantage that less affects the porosity of the support does not penetrate deeply into the porous support. The degree of filling of the pores can be confirmed by a scanning electron microscope (Scanning Electoron Microsope, SEM).

In one embodiment of the present invention, the porous support is not limited thereto, and may be formed by heat-treating a ceramic precursor including a ceramic and a metal salt.

In an exemplary embodiment of the present invention, the ceramic is a metal oxide; Metal borides; Metal carbides; And it may be used to include one or two or more selected from the group consisting of a group consisting of a metal nitride and the precursor of the aforementioned ceramic group, but is not limited thereto.

In another embodiment, the ceramic is a metal oxide; Metal borides; Metal carbides; And one or two or more selected from the group consisting of metal nitrides, but is not limited thereto.

As a specific example of the ceramic, aluminum oxide (Al ₂ O ₃ ); Aluminum oxide precursors; Yittria stabilized zirconia (YSZ); Scandia stabilized zirconia (ScSZ); Gadolinium doped ceria (GDC); Samarium doped ceria (SDC); Lanthanum Strontium Gallate Magnesite (LSGM); Nickel oxide (NiO); Copper oxide (CuO or Cu ₂ O); Titanium dioxide (TiO2); Spinel (MgAl ₂ O ₄ ), Mullite, Pyrophyllite; Silicon oxide (SiO2); Magnesium oxide (MgO); Iron oxide (Fe3O2, Fe2O3); Silicon carbide (SiC); And it may include one or two or more selected from the group consisting of nitrogen carbide (SiN). An example of the precursor of aluminum oxide is Boehmite (AlO (OH)), but is not limited thereto.

The metal salt includes salts of various metals commonly used in the art, such as nickel, copper, zirconium, yttrium, cerium, gadolinium, and a single metal salt or two or more polymetal salts can be used. Specifically, the multi-metal salts include nickel-nitrate hexahydrate, zirconyl-nitrate hydrate and yttrium-nitrate yttrium-nitrate. hexahydrate); Nickel-nitrate hexahydrate, gadolinium-nitrate hydrate, and cerium-nitrate hexahydrate; And copper-nitrate hexahydrate, gadolinium-nitrate hydrate, and cerium-nitrate hexahydrate. Combinations of multiple metal salts can be used, but the present invention is not limited to the use of multiple metal salts of these specific groups.

In one embodiment of the present invention, at least a portion of the metal salt may be reduced to metal by heat treatment.

The ceramic is 30% by weight to 80% by weight based on the entire porous support after the heat treatment, and the metal may be included by 20% by weight to 70% by weight.

In one embodiment of the present invention, the porous support has a plurality of pores, 30 to 70% by volume, preferably 30% by volume relative to the total volume of the support to facilitate the movement of materials such as fluid, gas, etc. It may have a porosity of 40 to 40% by volume.

The average diameter of the pores of the porous support may be 0.01 μm to 1000 μm, preferably 0.1 μm to 100 μm, and more preferably 0.5 μm to 5 μm.

The pore size can be measured using the method of Mercury Intrusion Porosimetry, Liquid Liquid Displacement or capillary flow porometer. That is, while sequentially changing the pressure of the unreacted inert gas, a wetting medium that wets the porous ceramic membrane corresponding to the sample is penetrated into the porous ceramic membrane pores or extruded. In this process, the pressure at a specific point, the weight of the medium, and the gas flow rate are recorded. Thereafter, the size of the pores can be calculated using the Laplace equation (ASTM, F316-03, Standard test methods for pore size characteristics of membrane filters by bubble point and mean flow pore test). In the present invention, the pore size measured by the mercury impregnation method was used. In addition, the pore size of the surface of the ceramic film can be confirmed by SEM, and the permeability of a fluid (liquid or gas) through the ceramic film at a constant pressure can be measured and the pore size can be inverted in the Hogen Poiseuille equation.

In another exemplary embodiment, the pores of the porous support may serve as channels. The channel means a passage through which a fluid or gas material moves in the porous support.

In one embodiment of the present invention, the solid particles may be carbon-based particles or particles capable of chemical etching.

In one embodiment of the present invention, the solid particles may be carbon-based particles. These materials have the property of changing from high temperatures to gases in air and inert atmospheres. The carbon-based particles may have carbohydrate-based particles having a carbon content of 100% and being present as a solid particle and having a carbon content of less than 100%. Specifically, the examples of the carbon-based particles include carbon black, graphite, carbon nanotube, carbon fiber, graphene, and graphene oxide, fullerene, activated carbon, starch, cellulose, cellulose, glucose, and polysaccharides (sucrose). .

In one embodiment of the present invention, the solid particles may be carbon nanotubes. Since the carbon nanotube has a long length and a flexible shape, it can efficiently fill the pores of the porous support, and has the advantage of easily maintaining the porosity of the porous support.

In another exemplary embodiment of the present invention, the solid particles may be particles capable of chemical etching. As an example, it may be a silica sphere, an inorganic powder prepared by a Stober method, but is not limited thereto.

In one embodiment of the present invention, the method for filling the solid particles is spin coating, dip coating, vacuum filtration, inkjet printing, gravure printing, spray coating, doctor blade, bar coating, gravure coating, Methods such as brush painting can be used.

In another embodiment of the present invention, the step of filling the pores of at least a portion of the porous support with solid particles may be made by filling the carbon-based particles with a wet process using water or an organic solvent. More specifically, a wet process in which a dispersion in which the carbon-based particles are evenly dispersed is prepared or a viscous paste is formed by combining an organic binder and a dispersant may be used. Examples of the wet process include spin coating, dip coating, vacuum straining, strain coating, duck blade, bar coating gravure coating, brush painting, inkjet printing, but are not limited to the above method.

Carbon-based particles that can be used in the wet process are carbon black, graphite, carbon nanotube, carbon fiber, graphene, graphene It may include one or more selected from oxide, fullerene, activated carbon starch, cellulose, glucose, and polysaccharide.

In one embodiment of the present invention, the step of filling at least a portion of the pores of the porous support with solid particles is made by filling a carbon-based particle other than a polymer or oligomer with a wet process using water or an organic solvent. May be

In one embodiment of the present invention, the method for filling the solid particles can be made without the use of a solvent. That is, a dry method may be used, for example, a dry rub method, a tapping method in which the filling particles are lifted without a dispersion medium solvent on the support and compacted and evenly charged while giving a constant vibration and force. There may be a vacuum method in which particles are partially infiltrated into the pores of the support to fill, and preferably, a dry rub method may be used, but is not limited to the above method. When no solvent is used, it is economical and suitable for mass production compared to the wet method. In addition, since the filled solid particles prevent the separation layer particles from deeply penetrating into the porous support, there is an advantage that the porosity of the support is less affected.

In an exemplary embodiment of the present invention, the separation layer may include, but is not limited to, a silica material, an organic-containing amorphous silica material, or a carbonaceous material as the outermost layer. Specifically, it is preferable that the separation layer includes at least one of Si, Ti, Zr, and Al. This makes it possible to make the separation layer a ceramic member such as SiO ₂ , TiO ₂ , Al ₂ O ₃ , ZrO ₂ , zeolite, mullite, and mixtures thereof, and all membranes made of these materials have separation performance. At the same time, it can have high acid resistance.

In one embodiment of the present invention, the separation layer may be formed by a sol-gel method, a CVD method, a sputtering method, or the like.

In one embodiment of the present invention, the formation of the separation layer may be achieved by the coating method. More specifically, after the particles forming the separation layer are prepared as a dispersion liquid having dispersion stability secured by using a dispersant and a dispersion medium, the separation layer may be formed by dipping the porous support into the dispersion liquid. The dispersion medium may be both an aqueous dispersion medium and a non-aqueous dispersion medium, specifically water; Tetra hydrofuran (THF); Isopropyl alcohol; Normal propyl alcohol; ethanol; Methanol; Normal butyl acetate; toluene; Hexane; Ethyl acetate; Ketone-based solvents containing acetone; α-terpineol (α-terpineol) or a mixture thereof can be used, preferably water, alcohol-based organic solvents can be used. However, the use of the solvent is not limited to those specified above, and a suitable dispersion medium may be used according to solubility and compatibility with the dispersant used.

In the present specification, the dispersant refers to a surfactant that serves to prevent aggregation between carbon particles while surrounding the surface of the carbon-based particles. The dispersing agent can prevent agglomeration by using an electrostatic repulsive force by lifting a charge or by a mechanism that gives a steric hindrance by a polymer chain. Specifically, the dispersant using electrostatic repulsion is SDS (Sodium Dodecyl Sulfate, C12H25SO4Na), bromide bromide (CTAB), and the dispersant using steric hindrance is polyvinyl pyrrolidone (Poly (vinyl pyrrolidone), PVP), but is not limited thereto.

In an exemplary embodiment of the present invention, the thickness of the separation layer may be 1 nm to 1,000 μm, preferably 10 nm to 100 μm, more preferably 100 nm to 10 μm.

In one embodiment of the present invention, the separation layer may be porous having pores, and the average diameter of the separation layer pores may be 0.01 nm to 100 μm, preferably 0.1 nm to 1000 nm. Measurement of the size of the pores may be performed in the same manner as the method for measuring the pores of the porous support described above.

In the present invention, removal means that the solid particles become gaseous by heat treatment or disappear by chemical etching.

The heat treatment means a temperature higher than room temperature.

In one embodiment of the present invention, the heat treatment temperature is 400 ° C to 2500 ° C, 600 ° C to 1500 ° C, preferably 800 ° C to 1800 ° C, and the heat treatment time is 30 minutes or more and 100 hours or less, preferably 1 hour It may be more than 48 hours. The heat treatment is heat-treated at a temperature of 400 ° C. or higher, and the solid particles become gaseous and removed, and the sintering of the separation layer is started. It can prevent the internal pores from disappearing.

In the present invention, sintering means a phenomenon in which when the heat treatment is performed at a constant temperature, particles of the porous support or particles of the separation layer are brought into close contact with each other and harden.

In order to form the intermediate layer, an energy costly firing process is required, but the manufacturing method according to an exemplary embodiment of the present invention has an effect of reducing process time and process cost since there is no step of forming the intermediate layer.

As an exemplary embodiment of the present invention, a ceramic film manufactured according to the above manufacturing method is provided.

As a specific embodiment of the present invention, the ceramic membrane may be composed of only a support and a separation layer without an intermediate layer. Through this, the total permeation resistance is reduced, and the membrane filtration throughput of the ceramic membrane can be increased. On the other hand, if there is no step of filling the carbon, the particles of the separation layer penetrate into the pores of the porous support to fill the pores, and the total permeation resistance increases to decrease the membrane throughput.

Hereinafter, examples will be described in detail to specifically describe the present invention. However, the embodiments according to the present invention may be modified in various other forms, and the scope of the present invention is not interpreted to be limited to the embodiments described below. The embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

<Example / Comparative Example>

<Comparative Example>

An alumina porous support having a pore size of 0.85 μm was prepared. The cross section and surface of the porous support were observed using SEM, and the corresponding SEM image is shown in FIG. 2.

Subsequently, a dispersion liquid having dispersion stability secured by using a separated organic particle having a diameter of 0.43 µm as a dispersant using a mixed organic solvent of PVP and toluene and isopyl alcohol as a dispersion medium. A separation layer is formed by deep coating the porous support that is not filled with solid particles in the dispersion.

Thereafter, heat treatment is performed at a temperature of 1000 ° C. or higher to prepare a ceramic film.

After heat treatment, the cross-section and surface of the porous support were observed using SEM, and the corresponding SEM image is shown in FIG. 3.

<Example 1>

A small amount of carbon black having a particle size of 0.5 μm is placed on one surface of the porous alumina support having a pore size of 0.85 μm. Thereafter, the carbon black is filled with pores of the porous support by a dry scrubbing method applied while applying pressure while turning, rubbing and pressing in a circular motion from the top to the bottom. It can be confirmed by contrast difference that the pores are filled with carbon black. After sufficient rubbing, the surface of the porous support is wiped off with a dry cloth or wipeall to remove excess carbon black.

Subsequently, a dispersion liquid having dispersion stability secured by using a separated organic particle having a diameter of 0.43 µm as a dispersant using a mixed organic solvent of PVP and toluene and isopyl alcohol as a dispersion medium. A separation layer is formed by dip coating the porous support on the dispersion.

Thereafter, heat treatment is performed at a temperature of 1000 ° C. or higher to prepare a ceramic film.

Before and after heat treatment, the cross-section and surface of the porous support were observed using SEM, and the corresponding SEM images are shown in FIGS. 4 and 5.

<Example 2>

A ceramic film was prepared in the same manner as in Example 1, except that a plate-like graphite having a width of 5 μm was used instead of carbon black.

After heat treatment, the cross-section and surface of the porous support were observed using SEM, and the corresponding SEM image is shown in FIG. 6.

<Example 3>

A ceramic film was prepared in the same manner as in Example 1, except that carbon nanotubes were used instead of carbon black.

Before and after the heat treatment, the cross-section and surface of the porous support were observed using SEM, and the corresponding SEM images are shown in FIGS. 7 and 8.

<Example 4>

Carbon black having a particle size of 0.5 μm is prepared by using a dispersant and a dispersion medium, thereby preparing a dispersion liquid having secure dispersion stability. Thereafter, the pores of the porous support are filled with carbon black by deep coating the alumina porous support having a pore size of 0.85 μm using the dispersion. Thereafter, the surface of the porous support is wiped off with a dry cloth or wipeall to remove excess carbon black.

Thereafter, a dispersion liquid having dispersion stability secured by using a dispersing agent and a dispersion medium is prepared. A separation layer is formed by dip coating the porous support on the dispersion.

Thereafter, heat treatment is performed at a temperature of 1000 ° C. or higher to prepare a ceramic film.

After heat treatment, the cross-section and surface of the porous support are observed using SEM.

<Example 5>

A ceramic film was prepared in the same manner as in Example 4, except that graphite was used instead of carbon black.

After heat treatment, the cross-section and surface of the porous support are observed using SEM.

In the case of the comparative example, it was confirmed from the SEM image of the cross section of the porous support of FIG. 2 that the separation layer particles penetrated into the pores of the porous support from the surface to a depth of 45 μm, and the SEM image of the surface of FIG. It was confirmed that there was a defect.

On the other hand, in Examples 1 to 5, it was confirmed that the separation layer particles did not penetrate into the pores of the porous support, and successfully formed the separation layer.

Claims (7)

Filling the pores of at least a portion of the porous support with solid particles;
Forming a separation layer on the porous support filled with the solid particles; And
Method of manufacturing a ceramic membrane comprising the step of removing the solid particles from the porous support. According to claim 1,
The solid particle is a method of manufacturing a ceramic film that is a carbon-based particle or a chemically etchable particle. According to claim 2,
The carbon-based particles are carbon black, graphite, carbon nanotube, carbon fiber, graphene, graphene oxide, fullerene ( A method of manufacturing a ceramic membrane comprising at least one selected from fullerene, activated carbon, starch, cellulose, glucose and polysaccharide. According to claim 2,
The method of manufacturing a ceramic film, wherein the particles capable of chemical etching include at least one selected from silica spheres and inorganic powders. According to claim 1,
The step of filling at least a portion of the pores of the porous support with solid particles is made without using a solvent. According to claim 1,
The step of filling the pores of at least a portion of the porous support with solid particles is a method of manufacturing a ceramic film, wherein the carbon-based particles are filled in a wet process using water or an organic solvent. Porous support; A ceramic membrane produced by the manufacturing method according to any one of claims 1 to 6, comprising a separation layer provided on one surface of the porous support.

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