KR100665579B1 - Faujasite zeolite membrane and a process for producing the same - Google Patents

Abstract

The present invention relates to a method for producing a faujasite (hereinafter abbreviated as FAU) type zeolite separator and a FAU zeolite separator prepared therefrom. More specifically, the present invention is a seed stock solution consisting of nanometer-sized FAU zeolite and α-alumina particles by vibrating and centrifuging commercially available FAU zeolite particles (usually 1 μm in diameter) and α-alumina balls. Obtaining a; Coating the seed stock solution on the porous α-alumina support by vacuum filtration; And hydrothermally treating the seed-coated α-alumina support as described above to grow seeds to form a dense FAU zeolite layer. According to this production method, the uniformity of the FAU zeolite coating layer is enhanced, the bonding strength with the α-alumina support is enhanced, and the defects on the surface of the support are uniformly coated to enable a large area of the zeolite separation membrane. And FAU zeolite membranes that can be industrially used in the field of carbon dioxide recovery from syngas streams, water removal from organic solvents such as alcohol and toluene, and separation of hydrocarbons that are difficult to separate by distillation.

FA zeolite, membrane, vibration and centrifugation, mixed seed, vacuum filtration

Description

Fauze zeolite membrane and method for producing the same {Faujasite zeolite membrane and a process for producing the same}

1 is a flow chart comparing the manufacturing method of the FAU zeolite separation membrane according to the present invention and the conventional manufacturing method of the zeolite separation membrane.

2 is a schematic view of the seed coating method by vacuum filtration according to the present invention.

Figure 3 is a schematic diagram of the hydrothermal reactor used for the formation of a dense FAU zeolite layer in the present invention.

Figure 4 is a schematic diagram of the cells used to evaluate the separation performance of the FAU zeolite membrane in the present invention.

Figure 5a is a scanning electron micrograph of a mixed seed consisting of FAU zeolite and α-alumina prepared by vibration grinding and centrifugation in the present invention.

5B shows commercial FAU zeolite particles having a diameter of about 1 μm used in the present invention (-▲-), FAU zeolite particles obtained after vibration milling of these zeolite particles (-●-), and FAU obtained by centrifugation after vibration grinding. It is a graph which shows the result of measuring the particle size distribution of zeolite particle (-■-) by the laser scattering method.

6A is a scanning electron micrograph of the cross section of the porous α-alumina support used in the present invention.

6B is a scanning electron micrograph of the surface of the porous α-alumina support coated with the mixed seed.

6c is a photograph of Si distribution on the surface of the porous α-alumina support coated with mixed seeds.

Figure 7a is a scanning electron micrograph of the cross section of the FAU zeolite membrane prepared according to the method of the present invention.

7B is a scanning electron micrograph of the surface of the FAU zeolite membrane prepared according to the method of the present invention.

FIG. 7C is a scanning electron micrograph of a cross-section of a FAU zeolite separation membrane showing that the FAU zeolite layer is densely formed on the pinhole surface defect of the porous α-alumina support according to the method of the present invention.

8A is a photograph of a 5, 10, 20 cm FAU zeolite separator prepared according to the method of the present invention.

Figure 8b is a graph showing the CO2 / N2 separation performance of the 5, 10, 20cm FAU zeolite separation membrane prepared in accordance with the present invention.

The present invention relates to a faujasite (hereinafter referred to as FAU) zeolite separator and a method for producing the same.

The separation of specific components from liquid and gaseous mixtures is key to the removal of environmentally hazardous substances and the recovery of high value added substances. Conventional separation techniques such as distillation, absorption, and adsorption have the disadvantages of requiring expensive equipment and high operating costs. Recently, a membrane separation technology using a membrane material that selectively passes a specific component in the mixture is in the spotlight. This is because the membrane separation technique requires a simple device and a low running cost compared to the conventional separation technique.

The core of membrane separation technology is the development of membrane materials with selective permeability to specific components. Membrane materials can be classified into polymer and inorganic membrane materials. Recently, the inorganic membrane material is attracting attention because of its thermal, chemical, mechanical stability, and excellent permeability, and representative inorganic membrane materials include carbon, silica, zeolite, and the like.

The FAU zeolite is a Na-Si-Al-O composition having a nanoporous channel of 7.4 kPa, and the FAU zeolite separation membrane consists of a porous α-alumina support providing mechanical strength and a dense FAU zeolite layer of several micrometers in thickness.

FAU zeolite membrane technology is an important technology with great industrial potential in the field of carbon dioxide separation from combustion flue gas and synthesis gas, water removal from organic solvents such as alcohol and toluene, and separation of hydrocarbons that are difficult to separate by distillation. This is because the nanoporous channel walls of the FAU zeolite layer have a chemical affinity for carbon dioxide, water, and hydrocarbons to selectively permeate carbon dioxide, water, and hydrocarbons, as well as silica, carbon, and other zeolite membranes with a nanopore channel diameter of 7.4Å. This is because carbon dioxide, water, and hydrocarbons have a higher permeation rate than the material.

For this reason, research on the manufacture of FAU zeolite membranes has been actively conducted in recent years. Generally, FAU zeolite membranes are prepared by growing seeds by hydrothermally treating a porous α-alumina support on which seeds are introduced to the surface to form a dense FAU zeolite layer. In more detail, the preparation of FAU zeolite membranes comprises the steps of selecting or preparing FAU zeolite particles for use as seeds, coating FAU zeolite seeds on the surface of porous α-alumina support, growing the coated zeolite seeds under hydrothermal conditions, and then dense FAU zeolites. Forming a layer.

What is important in this manufacturing method is the development of a coating technology that can reduce the cost of the zeolite material and overcome the defects of the support in the enlargement of the film for use in industry, not to mention the uniform deposition of the zeolite coating. The preparation of the zeolite particles used so far in the art has been made by purchasing expensive nanometer-sized FAU zeolites on the market, using hydrothermal synthesis, or making them through complex processes. In addition, coating techniques for zeolite particles used in the art include rubbing, slurry coating, dip coating, or coating using electrostatic attraction.

More specifically, after rubbing the FAU zeolite particles having a particle size of 200 mesh, the seed was introduced to the surface of the porous α-alumina support in the form of a tube having an outer diameter of 2.8 mm, a porosity of 39%, and a pore diameter of 150-170 nm. A method of producing a FAU zeolite membrane by hydrothermal treatment was proposed by K. Kusakabe Research Team (Kyushu University, Japan) [Japanese Patent No. JP 10036114 A2 and a research paper (Ind. Eng. Chem. Res. 36 (1997) 649). )]. These methods have the advantage of introducing seeds by simply scrubbing the porous α-alumina surface with large particle size commercial FAU zeolite particles. However, these methods have the disadvantage that they cannot introduce uniform seeds, and it is difficult to introduce seeds onto the inner surface of the porous α-alumina support having a small inner diameter tube.

In addition, a method of preparing a FAU zeolite membrane by slurry coating the commercially available FAU zeolite particles with an outer diameter of 12 mm and a porous α-alumina support having a pore diameter of 1.3 μm and then hydrothermally treating them to produce a FAU zeolite membrane Presented by H. Kita's team in Chem. Commun. (1997) 45, Sep. Purif. Technol. 25 (2001) 261. These methods have the advantage of introducing seeds by simply spraying or painting the FAU zeolite particle slurry onto the porous α-alumina tube surface. However, these methods have a disadvantage in that it is difficult to introduce seeds into the pores of the porous α-alumina support.

In addition, the FAU zeolite particles having a diameter of 0.5 μm were introduced to the surface of a porous α-alumina support having a diameter of 47 mm, a thickness of 30 mm, a pore diameter of 0.1 and 1 μm by a rubbing process, and then hydrothermally treated to obtain the FAU zeolite membrane. The manufacturing method has been presented by T. Yamaguchi's research team at Kyoto University, Japan [Ind. Eng. Chem. Res. 38 (1999) 4682]. They improved the method proposed by K. Kusakabe's team at Kyushu University, Japan, by using small 0.5 micron FAU zeolite particles as seeds, but did not overcome the difficulty of introducing uniform seeds in the rubbing process.

There is also a method of dipping a FAU zeolite particle having a diameter of 70 nm manufactured by hydrothermal synthesis onto a dense a-alumina surface, followed by hydrothermal treatment to form a FAU zeolite layer [J. Lulea University of Sweden. Sterte Research, Micropor. Mesopor. Mater. 38 (2000) 25]. These methods have the advantage of uniform introduction of seeds by simply dipping dense α-alumina support into an aqueous solution of nanometer-sized FAU zeolite particles, but the manufacturing process of 70 nm FAU zeolite particles is a complex process for a long time. The question remains whether the seed introduction method by immersion coating can also be applied to porous α-alumina supports.

There is also a method of preparing a FAU zeolite membrane by introducing FAU zeolite particles having a diameter of 50-150 nm into the surface of a porous α-alumina in the form of a disk having a diameter of 18 mm, a thickness of 1 mm, and a pore diameter of 0.2 μm, followed by hydrothermal treatment. [K. Weh and colleagues at the Institute of Applied Chemistry, Berlin-Adlershof, Germany, Micropor. Mesopor. Mater. 54 (2002) 27]. This method is a method of coating the surface of the support FAU zeolite particles using an electrostatic attraction by inducing a negative charge on the surface of the support by a negative charge to the FAU zeolite particles. These methods have the advantage of introducing seeds uniformly by using nanometer-sized FAU zeolite seeds and electrical attraction by the seed introduction method, but the disadvantage is that the seed introduction method using electrical attraction is a long time complicated process. .

For practical use, the FAU zeolite separation membrane should have an area (hereinafter referred to as permeable effective area) of a dense FAU zeolite layer of 300 cm 2 or more. Even if there are minute defects with a diameter of 1 nm in the FAU zeolite layer, the separation performance of the FAU zeolite membrane is drastically degraded. The maximum permeation effective area of the FAU zeolite membrane reported by the research team is very small, 17 cm 2.

The difficulty with the preparation of large area FAU zeolite membranes having an effective penetration area of at least 300 cm 2 is due to the low reliability of growing seeds under hydrothermal conditions to form a dense FAU zeolite layer. This ultimately leads to (i) the presence of defects such as pinholes and steps on the surface of the porous α-alumina support, and (ii) conventional techniques utilizing rubbing, slurry coating, immersion coating, and electrical attraction. It is due to the fact that the seed introduction method is difficult to uniformly introduce seeds onto the porous α-alumina support surface.

To date, no specific application examples using a large area FAU zeolite membrane and a large area FAU zeolite membrane have been disclosed.

It is an object of the present invention to solve the problems described above, by developing a seed coating method and seed coating method different from the prior art to improve the reliability of dense FAU zeolite layer formation under hydrothermal conditions by increasing the large area FAU zeolite separation membrane To make it possible.

Specifically, it is an object of the present invention to provide a method for preparing nanometer-sized FAU zeolite seeds through a simple process and the FAU zeolite seeds produced thereby.

In addition, an object of the present invention is to provide a coating method capable of minimizing the effects of defects on the surface of the porous α-alumina support by uniformly coating the FAU zeolite seed on the surface of the porous α-alumina support in a short time.

In addition, another object of the present invention is a dense FAU zeolite layer by coating the FAU zeolite seed with a uniform and strong bond to the porous α-alumina support by using the seed prepared by the seed production method as described above and the coating method as described above. It is to provide a method for producing a FAU zeolite separation membrane formed.

In order to achieve the above object, the present invention provides a commercially available FAU zeolite and α-alumina balls in a container in a first embodiment, and vibration-pulverized and centrifuged the nanometer-sized FAU zeolite and α-alumina particles. It provides a method for producing a mixed seed consisting of.

In a preferred embodiment of this embodiment, commercially available FAU zeolite particles used for vibration milling may be FAU zeolite particles having a diameter of at least 1 μm. A representative example is HISIV-1000 zeolite particles from UOP, USA.

At this time, the vibration grinding may be performed for 1 to 48 hours at a speed of 200 to 900 cycles / minute, and the centrifugation may be performed for 1 to 60 minutes under 1,000 to 15,000 rpm. By adjusting the vibration grinding speed, the vibration grinding time, the centrifugation speed and the centrifugation time, the particle size of the seed can be controlled between 100 and 1000 nm and the particle size distribution area can be narrowed.

The nanometer-sized mixed seeds prepared as above are different from conventional micrometer-sized seeds when coated on the surface of porous α-alumina support, and thus uniformly coated on the surface of the support defect as well as the role of FAU zeolite seed. Can be minimized.

In a second aspect, the present invention provides a mixed seed consisting of nanometer-sized FAU zeolite and α-alumina particles prepared by such vibration milling and centrifugation.

Such mixed seeds range from 100 to 1000 nm in diameter, preferably from about 200 to 300 nm, and particularly preferably from about 230 nm.

In a third aspect, the present invention provides a coating method of zeolite seeds, characterized in that the mixed seed consisting of nanometer-sized FAU zeolite and α-alumina particles is coated on the porous α-alumina support using vacuum filtration.

In this coating method, the mixed seed consisting of nanometer-sized FAU zeolite and α-alumina particles is a mixed seed prepared according to the first aspect of the present invention described above, but can be used in the coating method using the vacuum filtration of the present invention. Seeds are not limited to this.

This coating method can uniformly coat the seeds within a shorter time than the prior art, and the coating amount and coating thickness can be controlled by adjusting the amount of seed storage solution used for coating, vacuum pressure, filtration time, and the like.

In general, the vacuum pressure is 100 to 700mmHg, the filtration time is 1 to 60 minutes is sufficient, depending on the size of the membrane to be prepared by those skilled in the art will be able to perform appropriately selected.

In a fourth aspect, the present invention comprises the steps of (i) simply preparing a mixed seed consisting of nanometer-sized FAU zeolite and α-alumina particles by vibratory grinding and centrifugation, and (ii) porous α- by vacuum filtration. And uniformly coating the seeds on the surface of the alumina support, and (iii) growing the seeds under hydrothermal conditions to form a dense FAU zeolite layer.

The preparation and coating method of the mixed seed is as described above, but will be described in more detail below with reference to the prior art with respect to the manufacturing method of the FAU zeolite separation membrane according to the present invention (see Fig. 1).

(i) Preparation of mixed seed of nanometer size

In the present invention, unlike conventional hydrothermal synthesis method, which is a conventional method for producing FAU zeolite seeds, commercial FAU zeolite particles are vibrated and centrifuged to prepare mixed seeds consisting of nanometer-sized FAU zeolite and α-alumina particles.

Seed production technology according to the present invention, unlike the conventional method for producing seeds by hydrothermal synthesis method can produce a seed having a narrow particle size distribution and nanometer size in a simple process, and also the vibration grinding speed (200-900 cycles / min), The particle size (100-1000 nm) and the particle size distribution of the seed can be controlled by adjusting the vibration grinding time (1-48hr), centrifugation speed (1,000-15,000rpm), centrifugation time (1-60min).

In addition, the seed produced according to the method of the present invention is not a conventional FAU zeolite single seed but a nanometer-sized mixed seed composed of FAU zeolite and α-alumina by abrasion of α-alumina balls introduced in the vibration grinding process.

These nanometer-sized mixed seeds, unlike conventional micrometer-sized seeds, are uniformly coated on the support defect surface as well as the FAU zeolite seed when coated on the porous α-alumina support surface, thereby minimizing the influence of the support defect.

(ii) seed coating by vacuum filtration

In the present invention, the seed is coated on the surface of the porous α-alumina by a vacuum-driven filtering method, unlike the conventional seed coating method such as rubbing, slurry coating, dip coating, and coating by electric attraction.

Figure 2 shows a schematic diagram of a vacuum filter developed in-house for seed coating in the present invention.

Seed coating technology by vacuum filtration developed in the present invention can uniformly coat the seeds within a short time, unlike the prior art, and the amount of seed storage solution (see Example 1) (2-7.5 ml), pressure (100- 700mmHg), the coating amount and thickness can be controlled by adjusting the filtration time (1-60min).

In addition, the seed coating technology by vacuum filtration developed in the present invention can uniformly coat seeds on the inner surface as well as the outer surface of the tubular porous α-alumina support using the principle.

In addition, the seed coating technique by vacuum filtration developed in the present invention minimizes the effect of the porous α-alumina support surface defects by filling seeds with defects by coating the seeds preferentially on the defects of the surface of the porous α-alumina support.

In addition, the seed coating technique by vacuum filtration developed in the present invention, by introducing the seed smaller than the average pore diameter of the porous α-alumina support into the porous α-alumina support pores and the dense FAU zeolite layer formed by seed growth under hydrothermal conditions Enhances the bond strength of the porous α-alumina support.

(iii) formation of dense FAU zeolite layer by hydrothermal treatment

In the present invention, the seed-coated α-alumina support coated with the seed by vacuum filtration is hydrothermally treated in the same manner as in the prior art to form a dense FAU zeolite layer to prepare a FAU zeolite separation membrane.

Figure 3 shows a schematic diagram of a hydrothermal reactor made of Teflon material developed in the present invention for the formation of a dense FAU zeolite layer under hydrothermal conditions. Unlike the conventional hydrothermal reactor, the hydrothermal reactor developed in the present invention includes a jig capable of vertically introducing a seed-coated α-alumina support.

The FAU zeolite separation membrane was prepared by vertically introducing a porous α-alumina support (see Example 2) coated with seeds in a hydrothermal solution of Al2O3: SiO2: Na2O: H2O = 0.5-2: 5-15: 14: 840. Prepared by hydrothermal treatment at 120 ° C. for 4-48 hours.

The Si / Al ratio of the FAU zeolite layer of the prepared FAU zeolite separation membrane was hardly affected by the amount of Al 2 O 3 in the hydrothermal solution, while it was controlled in the range of 1.3-1.8 due to the large influence on the amount of SiO 2 in the hydrothermal solution.

The thickness of the FAU zeolite layer of the prepared FAU zeolite membrane was affected by the hydrothermal solvent composition, the hydrothermal temperature, and the hydrothermal time, and was controlled in the range of 1-6 μm.

The separation performance of the FAU zeolite separation membrane prepared by hydrothermal treatment of the seed-coated α-alumina support by the vacuum filtration method using the mixed seed as described above can be confirmed by evaluating the CO 2 / N 2 separation characteristics described in the present specification. . In addition to the evaluation method, those skilled in the art will appreciate that the separation performance may be evaluated through a water removal method or a hydrocarbon method that is difficult to separate by distillation in an organic solvent such as alcohol or toluene using a zeolite separation membrane.

Figure 4 shows a schematic diagram of the cell developed in the present invention for evaluating the CO2 / N2 separation performance of the FAU zeolite separation membrane. Unlike the conventional evaluation cell, the separation performance evaluation cell developed in the present invention can separate the central part, thereby minimizing damage to the separation membrane when the separation membrane is mounted.

The CO2 / N2 separation performance of the FAU zeolite separation membrane is evaluated by flowing a mixed gas of CO2 and N2 to the outside where the FAU zeolite layer is formed and by flowing He gas inside the FAU zeolite layer. The driving force at which CO2 and N2 pass through the FAU zeolite layer at this time is due to the partial pressure gradient of CO2 and N2 across the FAU zeolite layer.

The CO2 / N2 separation performance of the FAU zeolite membrane is characterized by the concentration of CO2 (0-100%), inlet gas velocity (0-400ml / min), inlet gas pressure (1-5bar), It is evaluated while varying the He induction gas velocity (0-200 ml / min) and the permeation temperature (room temperature -120 DEG C).

Increasing the concentration of CO2 in the injection gas increases the CO2 permeation flux while decreasing the N2 permeation rate, thus increasing the CO2 / N2 selectivity. Increasing the feed gas velocity maintained the CO2 permeation rate but slightly decreased the N2 permeation rate while increasing the CO2 / N2 selectivity. Increasing the feed gas pressure results in a slight increase in CO2 and N2 permeation rates while decreasing CO2 / N2 selectivity.

Increasing the He induced gas velocity increases the CO2 and N2 permeation rates and increases the CO2 / N2 selectivity. Increasing the permeation temperature almost maintains the CO2 permeation rate while increasing the N2 permeation rate, thereby decreasing the CO2 / N2 selectivity.

In a fifth aspect, the present invention provides a dense FAU zeolite layer consisting of FAU zeolite mixed seeds having a particle size ranging from 10 to 1000 nm, a narrow particle size distribution, a Si / Al ratio ranging from 1.3 to 1.8 and a layer thickness ranging from 1 to 6 μm. ; An intermediate layer consisting of a FAU zeolite and an α-alumina support; And it provides a FAU zeolite separator containing a support layer consisting of only porous α-alumina.

The FAU zeolite membrane of the present invention can be industrially used in the field of carbon dioxide recovery in the combustion flue gas and synthesis gas stream, the removal of water from the organic solvent such as alcohol, toluene, and the separation of hydrocarbons difficult to separate by distillation.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are only presented on the basis of the most preferred embodiments so that the technical details of the present invention can be easily carried out by those skilled in the art, it is obvious that the scope of the present invention is not limited to the examples. .

<Example 1>

This example is intended to explain in detail one embodiment of a preferred method of preparing nanometer-sized mixed seeds for use in preparing the FAU zeolite separation membrane of the present invention.

First, 1 g of commercial FAU zeolite particles having a diameter of 1 μm were placed in a 50 ml volume of Teflon vessel, and 90 g of α-alumina balls having a diameter of 1 mm and 20 ml of water were added to the Teflon vessel. Thus, a Teflon container containing commercial FAU zeolite particles, α-alumina balls, and water was mounted in a vibration mill and operated for 24 hours at a speed of 500 cycles / min.

After vibration grinding, the α-alumina ball was separated from the milky white solution by a glass filter. At this time, the pieces of Teflon broken during the vibration grinding are also removed together with the α-alumina balls.

Then, by centrifugation at 6,000 rpm for 10 minutes, large particles in the milky white solution obtained by the vibration grinding were precipitated at the bottom. The precipitated large particles were discarded and only the pale milky solution was recovered.

The recovered pale milky white solution is added to water to make a total volume of 200 ml to obtain a nearly clear solution. This is called seed stock solution. The seed stock solution did not settle to the bottom of the container even after several days of storage.

As a result of X-ray analysis of the seed stock solution prepared by the above-mentioned vibration pulverization and centrifugation, the seed was confirmed to be a mixed seed composed of nanometer-sized FAU zeolite and α-alumina particles. This was judged to be due to abrasion of the α-alumina balls during the vibration grinding.

Figure 5a shows a scanning electron micrograph of the mixed seeds prepared in the above-mentioned grinding and centrifugation conditions. The prepared seed was nanometer size and it was confirmed that the particle size distribution is narrow.

Figure 5b is a commercial FAU zeolite particle aqueous solution (HISIV-1000 NaY zeolite,-▲-) used as a raw material, a milky white aqueous solution (-●-) obtained in the above-mentioned vibration grinding conditions, prepared in the above-mentioned vibration grinding and centrifugation conditions The particle size distribution of the particles in the seed storage solution (-■-) was measured by laser scattering. The average particle diameter of the commercial zeolite aqueous solution is 1063 nm and the average particle diameter of the aqueous solution obtained after the vibration milling is 428 nm, whereas the mixed seeds prepared by the above-mentioned vibration milling and centrifugation are nanoparticles having an average particle diameter of about 230 nm and a narrow particle size distribution. It was.

Through these results, the method for preparing zeolite particles by vibrating grinding and centrifugation according to the present invention is different from the conventional method for preparing seeds by hydrothermal synthesis, and a method capable of producing seeds having a narrow particle size distribution and nanometer size by a simple process. I could confirm that.

<Example 2>

This example is intended to demonstrate that the coating method according to the invention is a useful method for coating zeolite seeds.

In this experiment, a porous α-alumina support having an outer diameter of 10 mm, an inner diameter of 7 mm, an average pore diameter of 120 nm, and a length of 50, 100, or 200 mm was used in some cases. Figure 6a shows a scanning electron micrograph of the cross section of the porous α-alumina support used in the present invention.

2 shows a vacuum filtration apparatus useful for the coating method of the zeolite seed according to the present invention. 2, the seed solution (2 in FIG. 2) diluted with 150 ml water of the 4 ml of the seed storage solution prepared in Example 1 was injected into the seed injection container (1 in FIG. 2). Committed to. One end of the porous α-alumina support (3 in Fig. 2) tube is blocked with a rubber stopper (4 in Fig. 2) and the other end is a rotary vacuum pump (5 in Fig. 2) using a rubber tube (⑤ in Fig. 2). ). A triangular flask (6 in Fig. 2) is placed between the support and the rotary vacuum pump to prevent the seed solution (2 in Fig. 2) from passing through the porous α-alumina support by the vacuum pump into the rotary vacuum pump. .

The on-off valve (7 in FIG. 2) was closed and the rotary vacuum pump (X in FIG. 2) was started. At this time, the pressure was adjusted to 150 mmHg using a vacuum gauge (8 in FIG. 2) and a metering valve (9 in FIG. 2).

When the pressure was stabilized to 150mmHg, the on-off valve (7 in Fig. 2) was opened and the mixed seeds were vacuum-coated on the surface of the porous α-alumina support for 20 minutes. After 20 minutes had elapsed, the pressure was gradually adjusted to the atmospheric pressure (760 mmHg) using a metering valve (9 in Fig. 2). Porous α-alumina support tubes coated with mixed seeds on the surface by vacuum filtration were collected in a vacuum filter and stored in a 110 ° C. oven.

Scanning electron micrographs of the surface of the porous α-alumina support coated with the mixed seed under such vacuum filtration conditions are shown in FIG. 6B. Smaller than the α-alumina particles constituting the porous α-alumina support, the mixed seed-shaped particles shown in FIG. 5A were uniformly coated on the porous α-alumina support surface (FIG. 6C).

FIG. 6C shows a Si distribution photograph obtained by EDS analysis while analyzing the surface of the porous α-alumina support coated with the mixed seed under a vacuum filtration condition by scanning electron microscopy. As can be seen from the electron micrograph, the Si atoms were uniformly distributed on the surface of the porous α-alumina support coated with the mixed seed. Considering that FAU zeolite is a composition of Si-Al-Na-O and α-alumina is a composition of Al-O, the uniform Si distribution indicates that the mixed seeds coated by vacuum filtration are uniformly coated on the porous α-alumina support surface. it means.

<Example 3>

This example illustrates a preferred method of forming a dense FAU zeolite layer under hydrothermal conditions using a porous α-alumina support coated with seeds on the surface using mixed seeds and vacuum filtration.

In the hydrothermal solution for seed growth, NaAlO2 was used as the Al2O3 raw material, water glass was used as the SiO2 raw material, NaOH was used as the Na2O raw material, and water was used as the distilled water. The hydrothermal solution was prepared by mixing the raw materials so that the molar ratio of Al2O3: SiO2: Na2O: H2O was 1: 6: 14: 840 and then mixing and aging at room temperature for 24 hours. The volume of the hydrothermal solution was 500 ml.

A porous α-alumina support (3 in FIG. 3) coated with a surface of 50, 100, and 200 mm lengths prepared by Example 2 was inserted into a Teflon jig (2 in FIG. 3), and a volume of 400 ml Teflon container ( In Fig. 3), the support was mounted vertically. 330 ml of a hydrothermal solution (4 in Fig. 3) was added to the Teflon container and the Teflon container was sealed using a Teflon cap (6 in Fig. 3) equipped with an O-ring (5 in Fig. 3). During sealing, the rod is inserted into the hole in the stopper and the container (7 in Fig. 3) to facilitate sealing.

The sealed hydrothermal reactor was mounted in a convection oven, heated to 110 ° C. at 1 ° C./min, maintained for 24 hours, and cooled again at 1 ° C./min at room temperature. It was confirmed by scanning electron microscopy that the FAU zeolite seed was grown under the above-mentioned hydrothermal conditions to form a dense FAU zeolite layer on the surface of the porous α-alumina support (FIGS. 7A to 7C). The prepared FAU zeolite separation membrane was washed three times by filtration and stirring and stored in a desiccator with silica dehumidifier at room temperature.

7A and 7B show scanning electron microscopes of the cross section and the surface of the FAU zeolite separation membrane prepared using the 5 cm long support under the above conditions, respectively. The prepared FAU zeolite membrane consisted of a dense FAU zeolite layer, an intermediate layer consisting of FAU zeolite and α-alumina, and a porous α-alumina support portion. The thickness of the dense FAU zeolite layer was about 5 μm and the Si / Al molar ratio was about 1.3 as measured by EDS composition during the scanning electron microscope analysis.

The formation of the intermediate layer consisting of the FAU zeolite and α-alumina was analyzed as a phenomenon in which small FAU zeolite seeds were introduced into the pores of the porous α-alumina support surface during seed coating by vacuum filtration according to Example 2.

7C shows a scanning electron micrograph of another cross section of the FAU zeolite separation membrane prepared under the hydrothermal conditions described above. The FAU zeolite layer was well formed on the pinhole defect surface of the α-alumina support surface, and in particular, the phenomenon in which the FAU zeolite filled the pinhole defect was observed. It was analyzed that FAU zeolite seed was uniformly coated on the pinhole surface of the support during seed coating by vacuum filtration, and seed appeared to fill the pinhole preferentially.

<Example 4>

This example is to confirm the performance of the FAU zeolite separation membrane prepared as in Example 3.

The performance of the zeolite separation membrane was confirmed through evaluation of the CO 2 / N 2 separation performance.

Stainless steel tubes were attached to both ends of the FAU zeolite separation membranes of 50, 100 and 200 mm length prepared in Example 3 using high temperature epoxy. Figure 8a shows a photograph of FAU zeolite separation membranes 50, 100, 200mm in length with a stainless steel tube attached. Epoxy adhesion reduced the permeation effective length of the FAU zeolite membrane by about 30 mm.

A FAU zeolite separation membrane fitted with a stainless steel tube was mounted in the gas separation evaluation cell shown in FIG. 4. A mixed gas having a 1: 1 ratio of CO 2 and N 2 was introduced outside the FAU zeolite layer at a rate of 350 ml / min. At this time, the pressure of the mixed gas of CO2 and N2 was 2 bar. He induced gas was introduced at a rate of 150 ml / min without the FAU zeolite layer. At this time, the pressure of He gas was 1 bar. The temperature of the evaluation cell equipped with the FAU zeolite separation membrane was maintained at 30 ° C. by an externally mounted electric furnace.

The CO2 / N2 separation characteristics (permeation rate and CO2 / N2 selectivity) of FAU zeolite separation membranes having lengths of 50, 100, and 200 mm under the conditions described in FIG. 8B are shown. The FAU zeolite separation membrane with a length of 5 cm had a CO2 permeation rate of 3 x 10-2 mol / m2sec and a CO2 / N2 selectivity of 82. The FAU zeolite separation membrane with a length of 10 cm had a CO2 permeation rate of 2.5 x 10-2 mol / m2sec and CO2 / N2. The selectivity was 43, the 20 cm long FAU zeolite separation membrane had a CO 2 permeation rate of 2 × 10 −2 mol / m 2 sec and a CO 2 / N 2 selectivity of 25. As the length of the FAU zeolite membrane increased, the CO2 / N2 separation characteristics decreased, but all three specimens showed excellent CO2 / N2 separation characteristics.

In particular, since the large-area FAU zeolite separation membrane having a length of 20 cm and an effective effective area of 60 cm 2 exhibits excellent CO 2 / N 2 separation characteristics, the seed coating method of the mixed seed and vacuum filtration developed in the present invention is characterized by the growth of seeds under hydrothermal conditions. It has been shown that the reliability of dense FAU zeolite formation can be enhanced to enable the preparation of large area FAU zeolite separation membranes.

Although the technical details of the FAU zeolite separation membrane of the present invention and a method for producing the same have been described with the accompanying drawings, this is by way of example and not by way of limitation.

In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical details of the present invention.

When the seed coating method of the present invention as described above and the seed coating method by vacuum filtration are applied to the preparation of the FAU zeolite separation membrane, it is possible to produce a large area FAU zeolite separation membrane by enhancing the reliability of dense FAU zeolite layer formation.

Such a FAU zeolite separation membrane and a manufacturing method of the present invention is expected to contribute to the reduction of the apparatus and operation cost of the separation technology by industrialization of the faujasite zeolite separation membrane by providing a key technology to solve the large-area difficulty, which is an obstacle to commercialization of the FAU zeolite separation membrane. The large-area FAU zeolite separation membrane of the present invention is used for recovering carbon dioxide in combustion flue gas and synthesis gas, removing water contained in organic solvents such as alcohol and toluene, and separating hydrocarbons that are difficult to separate by distillation. It can contribute to the industrialization of membrane separation technology.

Claims (15)

Method for preparing a mixed seed consisting of nanometer-sized FAU zeolite and α-alumina particles by adding commercially available FAU zeolite and α-alumina balls to the vessel, vibration-pulverizing and centrifuging. The method of claim 1 wherein the commercially available FAU zeolite particles used for vibration milling are zeolite particles having a diameter greater than 1 μm. The method of claim 1, wherein the vibration grinding is performed at a speed of 200 to 900 cycles / minute for 1 to 48 hours, and the centrifugation is performed at 1,000 to 15,000 rpm for 1 to 60 minutes. Mixed seed consisting of FAU zeolite and α-alumina particles having a particle diameter in the range of 100 to 1000 nm. The mixed seed of Claim 4 manufactured by the method of Claim 1. The mixed seed of claim 5, wherein the particle diameter is about 230 nm. A method of coating a mixed seed consisting of FAU zeolite and α-alumina particles, characterized in that the mixed seed consisting of nanometer-sized FAU zeolite and α-alumina particles is coated on the porous α-alumina support by using vacuum filtration. The coating method according to claim 7, wherein the vacuum pressure is from 100 to 700 mmHg, and the filtration time is from 1 to 60 minutes. (i) simply preparing a mixed seed consisting of nanometer-sized FAU zeolite and α-alumina particles by vibratory grinding and centrifugation, and (ii) uniformly seeding the porous α-alumina support surface by vacuum filtration. Coating, and (iii) growing seeds under hydrothermal conditions to form a dense FAU zeolite layer. 10. The method of claim 9, wherein the commercially available FAU zeolite particles used for vibration grinding are zeolite particles having a diameter of more than 1 µm. The method of claim 9, wherein the vibration grinding is carried out for 1 to 48 hours at a speed of 200 to 900 cycles / minute, centrifugation is carried out for 1 to 60 minutes at 1,000 to 15,000 rpm, the production of FAU zeolite separator Way. 10. The method of claim 9, wherein the vacuum pressure is 100 to 700 mmHg, and the filtration time is 1 to 60 minutes. The method of claim 9, wherein the hydrothermal conditions are Al2O3: SiO2: Na2O: H2O is hydrothermally treated at 80 to 120 ℃ for 4 to 48 hours using a hydrothermal solution having a composition of 0.5-2: 5-15: 14: 840. Characterized in that the manufacturing method of the FAU zeolite membrane. A dense FAU zeolite layer composed of FAU zeolite mixed seeds having a particle diameter in the range of 10 to 1000 nm, a Si / Al ratio in the range of 1.3 to 1.8, and a layer thickness in the range of 1 to 6 μm; An intermediate layer made of a FAU zeolite and an α-alumina support; And a support layer composed of porous α-alumina only. The FAU zeolite separation membrane according to claim 14, which is produced by the production method as described in claim 9.

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