JP4522761B2 - Method for producing inorganic porous body - Google Patents

Description

  The present invention relates to an inorganic porous body and a method for producing the same. Specifically, the present invention relates to an inorganic porous body that can efficiently pass a fluid to be treated, for example, gas or liquid, and a method for manufacturing the same.

The porous body can separate, purify, or adsorb gas and liquid by controlling the pore diameter. Moreover, since the surface area is large, it is also useful as a catalyst support. For this reason, it is used in a wide range of fields. In particular, an inorganic porous body composed of an inorganic material is excellent in terms of heat resistance, chemical resistance, and the like, and thus is applied to gas separation at high temperatures and separation of various organic solvent mixtures. For example, a gas separation device that uses an inorganic porous material is expected to be an energy-saving device that does not involve phase change, can be expected to simplify the device and operation, and can be continuously operated. ing.
As such an inorganic porous material, for example, there is a material in which an inorganic porous film having a pore size of a desired size is formed on the surface of a high strength support having a relatively large pore size. By controlling the pore size of the inorganic porous membrane, separation, adsorption, etc. can be performed selectively using the fluid to be treated, that is, the difference in the size and properties of the gas and liquid molecules, particles, etc. it can. As a method for producing such an inorganic porous film, a sol-gel method (see Non-Patent Document 1), a CVD method, a hydrothermal synthesis method, an electrode oxidation method, and the like have been proposed.
On the other hand, Patent Document 1 discloses a method of forming an ion conductive film made of a dense oxide thin film on the surface of a porous ceramic support substrate by a pulse laser ablation deposition method (PLD).

JP 2003-147514 A Shoji Asaeda "Catalyst", Catalysis Society of Japan (1994), Vol. 36, No. 4, pp. 238-245

However, the thin film described in Patent Document 1 is a dense film and does not have pores. For this reason, although it is excellent in ionic conductivity, it cannot physically permeate the fluid to be treated, for example, molecules or particles contained in gas or liquid. Moreover, in the porous membrane produced by the conventional method as described in Non-Patent Document 1, the physical control of the pores is not significant and the separation of the fluid to be treated (for example, having a high permeation rate) is efficient. , Purification, or adsorption treatment was difficult. From such a current situation, an inorganic porous body having pores that can permeate molecules, particles, and the like contained in a fluid to be treated, and has improved processing efficiency (for example, a higher permeation rate) An inorganic porous body provided with a membrane is desired.
Therefore, the present invention has been developed to solve such conventional problems, and an inorganic porous body having an inorganic porous film through which molecules and particles contained in a fluid to be treated can efficiently permeate, and its An object of the present invention is to provide a method for producing such a porous body, that is, a method for producing a porous body provided with such a membrane.

The inorganic porous body disclosed here has a porous substrate and an inorganic porous film formed on the surface of the porous substrate. Then, a plurality of holes formed in the film is characterized in that are oriented in the thickness way direction Ryakumaku.

  In this inorganic porous body, the pores of the inorganic porous film are formed so as to be oriented in the predetermined direction. For this reason, the fluidity of the fluid to be treated, for example, gas or liquid molecules, particles, and the like is improved, and the fluid is easily transmitted. Accordingly, the permeation speed of molecules and particles contained in the fluid to be processed is improved, and separation processing and the like can be performed efficiently.

  In this inorganic porous body, the average pore diameter of the pores formed in the porous membrane is preferably in the range of 5 to 200 nm. When the average pore diameter is in this range, the fluid to be treated can be treated particularly efficiently. For example, relatively large molecules contained in the fluid to be treated, such as macromolecules, viruses, colloids to fine particles, can be selectively treated, for example, separated, purified, or adsorbed, depending on their pore sizes. Moreover, it can be used as a catalyst carrier, and allows the fluid to be treated to permeate at a high permeation rate while carrying the catalyst on a high surface area, thereby efficiently performing the catalytic reaction treatment.

In such an inorganic porous body, another preferable one is one in which the porous substrate and the porous membrane are made of the same or different ceramics. Since the porous substrate and the inorganic porous membrane are made of ceramic, they are particularly excellent in stability at high temperatures and chemicals. For this reason, it can be stably used for processing fluid at high temperatures.
In particular, the film is preferably composed mainly of stabilized zirconia. Stabilized zirconia has high mechanical strength and high fracture toughness. For this reason, it is excellent in stability and has high durability.

Moreover, this invention provides the method of manufacturing suitably the porous body disclosed here. That is, one embodiment of the method for producing an inorganic porous body disclosed herein is an inorganic porous body having a plurality of pores oriented in the film thickness direction on the surface of the porous substrate and having an average pore diameter in the range of 5 to 200 nm. This is a method for producing an inorganic porous body provided with a porous membrane. The method includes the steps of preparing a target composed of stabilized zirconia and a porous substrate composed of ceramic, and arranging the target and the porous substrate in a deposition chamber that can be depressurized, In an oxidizing gas atmosphere whose pressure is reduced to 1 to 200 Pa , and the frequency is approximately within a range of 5 to 500 Hz under a substantially constant temperature condition set in the oxidizing gas atmosphere and within a temperature range of 30 to 800 ° C. is irradiated with pulsed laser in the target, the vapor from the target thereby (referred to those suspended in the gas phase. hereinafter the same.) generating, by depositing the vapor on a surface of the porous substrate Forming the porous film.

  In the pulsed laser ablation (PLD) method, a target is irradiated with a pulsed laser to sequentially vaporize each target material (typically molecules, atoms, ions, nano- or micron-sized particles generated from the target by pulsed laser irradiation). It refers to particles (clusters). } And vapor made of material can be deposited on the surface of the substrate. Conventionally, this PLD method has been used for forming a dense film because the target material is vaporized and deposited on the surface of the substrate.

  However, the present inventors diligently studied this PLD method and considered the conditions in order to form an inorganic porous film on the surface of the porous substrate. As a result, the present inventor created the method disclosed herein by controlling the conditions for generating steam to predetermined conditions, and formed an inorganic porous material in which a plurality of pores oriented substantially in the film thickness direction were formed. We succeeded in forming a porous membrane on the surface of a porous substrate.

In this manufacturing method, the target is irradiated with the pulse laser under a substantially constant temperature condition set within a temperature range of 30 to 800 ° C. By performing irradiation with the pulse laser under a substantially constant temperature condition within a temperature range of 30 to 800 ° C., the pore diameter of the inorganic porous film can be controlled to a predetermined size. Therefore, an inorganic porous membrane having a substantially uniform pore diameter can be obtained.

Moreover, it is preferable that the atmosphere which performs the said porous film formation process is oxidizing gas atmosphere. In particular, when the inorganic porous film formed from the target inorganic material is an oxide , the inorganic oxide porous film can be efficiently formed by performing deposition in an oxidizing gas atmosphere.

  Preferably, the number of times of irradiation with the pulse laser is approximately 200,000 times or less. When the number of pulse laser irradiations is 200,000 or less, the orientation of the pores of the inorganic porous film can be formed particularly stably.

  In this manufacturing method, the energy of the pulse laser is preferably in the range of about 100 to 1200 mJ / pulse. If the energy of the pulse laser is within this range, an inorganic porous film having excellent pore orientation as described above can be suitably formed on the porous substrate surface.

Using the constructed porous substrate from ceramic. If the substrate is ceramic, its properties are unlikely to change even under severe conditions such as high temperatures and oxidation. For this reason, as described above, the inorganic porous film can be stably formed on the surface of the porous substrate.

If the target stabilization zirconia is configured, the porous ceramic film having excellent hole alignment property can be easily and stably formed.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters specifically mentioned in the present specification (for example, pulse laser frequency, atmospheric pressure, temperature, number of irradiations, target constituent material, and inorganic porous film configuration in the pulse laser ablation (PLD) method). Matters other than those necessary for the implementation of the present invention (for example, the type of pulsed laser, irradiation time, the structure of the porous substrate, the thickness of the inorganic porous film, etc.) are the conventional techniques in this field. It can be grasped as a design matter of a person skilled in the art based on this. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

  In the manufacturing method according to the present invention, a target is irradiated with a pulse laser having a predetermined frequency under a predetermined atmospheric pressure, and vapor is generated from the inorganic material constituting the target to form an inorganic porous film on the surface of the porous substrate. As long as it can be formed, various materials and configurations can be applied for that purpose.

The inorganic material constituting the data Getto, stabilize zirconia, and particularly yttria (e.g. 8 mole%) containing stabilized zirconia A.

  In addition, although the size of the target is not particularly limited, in order to be suitably used for a general PLD apparatus, the diameter is about 1 to 50 mm, particularly 30 to 45 mm, and the thickness is 0.5 to 10 mm. In particular, it is preferably about 2 to 5 mm.

Further, the surface roughness (Ra value) of the target is preferably 1 × 10 ² μm or less, and in the method of the present invention, it is about 1 × 10 ⁻³ to 1 × 10 ² μm, more preferably 1 × 10 ^−. A Ra target of about ^{2 to} 5 × 10 μm, particularly about 1 × 10 ⁻¹ to 1 × 10 μm can be preferably used. Moreover, the maximum value (Rmax value) of the surface roughness is preferably 1 × 10 ⁻¹ to 1 × 10 ² μm, more preferably 1 × 10 ^{−1 to} 3 × 10 μm, particularly 1 × 10 ⁻¹ to 1 ×. 10 μm. Even with a surface roughness in this range, an inorganic porous film having a uniform pore diameter can be formed.

The porous substrate used in the present production method, if example embodiment, alumina (e.g., alpha-alumina or γ- alumina), zirconia {preferably stabilized zirconia, in particular yttria (e.g. 3-8 mol%) containing stabilized Zirconia}, silica, titania, magnesia and other inorganic oxides. Alternatively, composite oxides such as mullite and zeolite can be used . Some have _{the, Si 3 N 4, SiC,} ZrC, include non-oxides such as HfC. A glassy material can also be used. Furthermore, the mixture of any 2 or more types of these may be sufficient . The good preferable ceramic material, alumina, zirconia, silica and / or titania. Particularly preferred is alumina and / or zirconia. Of these, stabilized zirconia is particularly preferred.

  The material (target) for forming the porous substrate and the porous film may be composed of the same material or different materials, and in particular, the porous substrate. And the porous membrane are preferably the same or similar materials. In this case, a porous body excellent in adhesion between the porous base material and the porous membrane can be produced.

The average pore size of the porous base material to be used is not particularly limited because it varies depending on the use of the obtained inorganic porous material, but is preferably 1 to 1 × 10 ⁴ nm, more preferably 1 to 5000 nm, and still more preferably. 2 to 2000 nm. Even with such a base material having a large average pore diameter, according to the present production method, the inorganic porous film can be uniformly formed on the surface thereof.

The surface roughness (Ra value) of the porous substrate is preferably 1 × 10 ² μm or less, and in the method of the present invention, about 1 × 10 ⁻³ to 1 × 10 ² μm, more preferably 1 × 10. ^A substrate of Ra of about ⁻³ to 5 × 10 μm, particularly about 1 × 10 ⁻³ to 1 × 10 μm can be preferably used. Moreover, the maximum value (Rmax value) of the surface roughness is preferably 1 × 10 ⁻¹ to 1 × 10 ² μm, more preferably 1 × 10 ^{−1 to} 3 × 10 μm, particularly 1 × 10 ⁻¹ to 1 ×. 10 μm. Even with a surface roughness in this range, an inorganic porous film having a uniform thickness can be formed on the surface.

  The porous substrate as described above may be used as it is, or when a material having a large pore diameter is used, it is preferable to form an intermediate layer on the surface of the porous substrate in advance. In this case, the preferred intermediate layer preferably has a pore size (average pore size) of about 2 to 500 nm. The method for forming the intermediate layer is not particularly limited, and for example, a conventionally known dip coating method is preferably employed. The material of the intermediate layer is not particularly limited, but is preferably selected from the viewpoint of matching the thermal expansion coefficient. For example, when the material of the porous substrate and the porous membrane are different, an intermediate layer of a material having a thermal expansion coefficient intermediate between the thermal expansion coefficient of the porous substrate and the thermal expansion coefficient of the porous membrane is formed. Is preferred. When forming an intermediate | middle layer, the thickness is although it does not specifically limit, Preferably it is 10 micrometers or less (for example, 10 nm-10 micrometers, Furthermore, 50 nm-5 micrometers, especially 100 nm-3 micrometers).

  The pulse laser that can be used in the present manufacturing method is a laser having a power capable of generating a vapor of an inorganic material (typically, a minute cluster of the target material) from the target by irradiating the target, If it has a frequency, it can select suitably according to the use without a restriction | limiting especially, and can use it. An example is a nanosecond pulse laser. Among these, an excimer laser, a YAG laser, and a ruby laser are preferable, and an excimer laser or a YAG laser is more preferable. In particular, among excimer lasers, KrF laser, ArF laser, and XeCl laser are preferable, and for example, a KrF laser with a wavelength of 248 nm and a pulse width of 30 ns is preferable.

The frequency of the pulsed laser is desirably higher than approximately 5 Hz, and preferably within the predetermined range, i.e., about 5 to about 500 Hz. More preferably, it is 10-100 Hz, More preferably, it is 10-80 Hz, Still more preferably, it is 10-50 Hz, Most preferably, it is 20-40 Hz. When the frequency is less than 5 Hz, the orientation of the inorganic porous film tends to decrease.
The pulse energy is not particularly limited, but is preferably in the range used in general laser pulse ablation deposition (PLD). For example, it is 100 to 1200 mJ / pulse, preferably 100 to 650 mJ / pulse, more preferably 200 to 500 mJ / pulse, and particularly preferably 300 to 450 mJ / pulse. However, higher energy can be used if the device can use higher energy.

  The number of pulse laser irradiations (that is, the number of shots) is not particularly limited. It can select suitably according to the thickness, the hole diameter, etc. of the inorganic porous membrane obtained. For example, it is preferably 200000 times or less. More preferably, it is 500 to 200000 times, more preferably 500 to 50000 times, still more preferably 1000 to 50000 times, particularly preferably 3000 to 40000 times, and most preferably 5000 to 30000 times. In the case of the number of irradiation times, an inorganic porous film particularly excellent in pore orientation can be stably formed.

The irradiation atmospheric pressure is preferably within the range of about 1 to about 200 Pa (for example, 0.01 to 2 Torr), more preferably 1 to 100 Pa (for example, 0.01 to 1 Torr), still more preferably 5 to 80 Pa, and further More preferably, it is 10-60 Pa, Most preferably, it is 15-50 Pa, Most preferably, it is 20-40 Pa (for example, 0.15-0.3 Torr).
Irradiation atmosphere gas at this time, if example embodiment, the oxidizing gas such as oxygen gas or air, and particularly preferably an oxygen-containing gas.

  The irradiation time can be appropriately selected depending on the thickness of the desired inorganic porous film, its pore diameter, the number of pulse laser irradiations, the frequency, and the like. For example, it is 1 to 30000 seconds, preferably 10 to 10000 seconds, more preferably 50 to 5000 seconds, and particularly 100 to 3000 seconds. When the irradiation time is in such a range, an inorganic porous film having pores with particularly high orientation can be obtained.

By keeping the temperature of the porous substrate when depositing the inorganic material from the target substantially constant, the pore diameter of the inorganic porous film can be controlled to be substantially constant. The preferred temperature range, especially for this is 30 to 800 ° C.. By maintaining the temperature within this temperature range and at a selected constant temperature, the average pore diameter can be controlled to be in the range of approximately 30 to 150 nm, for example. Moreover, when the selected temperature is in the temperature range of 500 to 800 ° C., the average pore diameter can be controlled to be in the range of 30 to 100 nm, for example. Or it can form by controlling an average hole diameter in the range of 100-150 nm by being in the temperature range of 30-400 degreeC, for example. Therefore, the average pore diameter of the formed inorganic porous film can be controlled within a desired range by controlling the temperature of the substrate within a predetermined range with respect to the type of substrate and target used. The heating rate at the time of heating the substrate to a predetermined temperature is not particularly limited, but is, for example, 1 to 30 ° C./min, preferably 3 to 20 ° C./min, particularly 5 to 15 ° C./min. Furthermore, the pore diameter of the inorganic porous membrane can be changed in the film thickness direction by changing the temperature of the substrate during the formation of the inorganic porous membrane. For example, by gradually lowering the temperature of the base material in the deposition step, the pore diameter can be gradually increased toward the surface of the film.

  When an inorganic porous film is formed under a temperature condition set at a relatively high temperature (for example, 400 ° C. or higher), and then the porous substrate is cooled to approximately room temperature, the cooling rate is 50 ° C./min. In the following, it is particularly preferable to control to 30 ° C./min or less. If the cooling rate is faster than this range, cracks may occur in the formed inorganic porous film.

  The thickness of the deposited inorganic porous film is not particularly limited, but is preferably 10 μm or less (for example, 10 nm to 10 μm, further 50 nm to 5 μm, particularly 100 nm to 3 μm). According to this production method, an inorganic porous film having highly oriented pores can be easily formed on a porous substrate as a thin layer in such a range.

  Furthermore, the obtained inorganic porous membrane can be subjected to heat treatment or other various post treatments. For example, heat treatment can be performed at 100 to 2000 ° C, preferably 500 to 1500 ° C, particularly 800 to 1300 ° C. By heat treatment, the moldability and mechanical strength of the inorganic porous membrane can be improved. The rate of temperature rise is not particularly limited, but is, for example, 1 to 30 ° C./min, preferably 3 to 20 ° C./min, and particularly 5 to 15 ° C./min. In addition, other treatments such as acid treatment, alkali treatment, plasma treatment, and microwave treatment can be performed for the purpose of surface modification.

Moreover, the porous body obtained by the production method disclosed herein can carry a catalyst on the surface and pores of the inorganic porous membrane. Alternatively, a dense layer can be partially formed on the surface of the inorganic porous membrane. As the catalyst to be supported or the dense layer to be formed, various materials can be selected without particular limitation depending on the desired purpose.
The catalyst can be supported or the dense layer can be formed by various known means. For example, slurry coating, sol-gel method, spin coating, etc. can be used. For example, the dense layer can be formed by a conventional pulse laser ablation deposition method (PLD). A particularly dense and uniformly thin dense layer (film) can be formed over a wide range by the pulsed laser ablation deposition method.

Any conventionally known catalyst material may be used as the material that functions as a catalyst. In particular, at least one metal catalyst material selected from the group consisting of palladium, platinum, nickel, rhodium, ruthenium, silver, tin, iron, and copper may be mentioned. Moreover, the alloy and mixture (namely, 2 or more types of material) of any combination of these may be sufficient. Of these, palladium, platinum, nickel, rhodium, and / or ruthenium are preferable, and palladium and / or platinum are particularly preferable. Alternatively, Ln _1-x Sr _x MnO ₃ (wherein Ln represents any element of lanthanoids (preferably La), x is a number satisfying 0 ≦ x <1), and Ln _{1- x} Sr _x CoO ₃ (wherein Ln represents any element of lanthanoids (preferably La), and x is a number satisfying 0 ≦ x <1), at least one compound selected from the group consisting of _x Sr _x CoO ₃ Examples include oxide catalyst materials. Furthermore, the mixture (namely, 2 or more types of materials) of the combination in any of these may be sufficient.

  According to the production method disclosed herein, an inorganic porous body having the inorganic porous film formed as described above on the surface of the porous substrate can be obtained. The present invention provides such an inorganic porous body.

In a preferred embodiment, the average pore diameter (for example, an estimated value by observation with an electron microscope ) of the inorganic porous membrane is in the range of 5 to 200 nm, particularly preferably in the range of 30 to 150 nm. Or the thing of a suitable average hole diameter can be selected according to the use used. For example, what has an average hole diameter of the range of 30-100 nm can be provided. Or what has an average hole diameter of the range of 100-250 nm can be provided.

For example, according to the present invention, an inorganic porous body in which a porous ceramic film having the above average pore diameter is formed on the surface of a porous ceramic substrate can be provided. As a ceramic base material and a ceramic film | membrane, what was described in the said manufacturing method can be mentioned. More preferably, an inorganic porous body in which the membrane is mainly composed of stabilized zirconia can be provided.
<Example>

The present invention will be described in more detail with reference to the following examples. However, the present invention is not intended to be limited to those shown in the examples.
<Example 1>
(1) Manufacture of inorganic porous body As a porous base material, the alumina porous base material which provided the intermediate | middle layer previously with the dip method was prepared. The alumina porous substrate had a porosity of 30%, an average pore diameter of 100 nm, a surface roughness (Ra value) of 0.2 μm, and a maximum value (Rmax value) of 1.4 μm. The porosity of the intermediate layer was 50%, the average pore diameter was 8.5 nm, the surface roughness (Ra value) was 0.06 μm, and the maximum value (Rmax value) was 0.76 μm.
On the other hand, yttria-stabilized zirconia was prepared as a target for pulsed laser ablation deposition (PLD). Yttria-stabilized zirconia was produced according to well-known ceramic production means. That is, zirconia powder containing 8 mol% yttria was pressed into a pellet and sintered at 1350 ° C. The size of the obtained pellet had a diameter of 38 mm and a thickness of 4 mm. The surface roughness (Ra value) was 0.22 μm, and the maximum value (Rmax value) was 2.06 μm.

  Next, yttria-stabilized zirconia was deposited on the surface of the alumina substrate by laser pulse ablation. As schematically shown in FIG. 1, the used apparatus 1 has a base material 5 and a target 7 arranged opposite to each other in a deposition chamber 3 that can be decompressed by a vacuum pump P (not shown). Yes. The target 7 is held by a target holder 8, and the base material 5 is held by a base material holder 6. Although not shown, the base material holder 6 is provided with a heating means so that the base material 5 can be heated to a predetermined temperature and the temperature can be maintained. The deposition chamber 3 is provided with a gas supply pipe 9 as means for supplying the reaction gas. In addition, a laser source (not shown) and an optical system for irradiating the target 7 with a predetermined laser are provided in the vicinity of the deposition chamber 3. As a result, the laser emitted from the laser source is focused by the objective lens 11 provided in the optical system, and applied to the target 7 through the transmission window 4 provided in the wall portion of the deposition chamber 3. At this time, the laser beam incident in the direction of the arrow in FIG. 1 through the objective lens 11 is focused on the target 7.

  First, the alumina porous substrate 5 was fixed by the substrate holder 6 and held in front of the target 7. And the alumina porous base material 5 was heated to 650 degreeC with the temperature increase rate of 10 degree-C / min with the heating means provided in the base-material holder 6. FIG. Next, while maintaining this temperature, the inside of the deposition chamber 3 was decompressed and oxygen gas was introduced, and the oxygen gas pressure in the deposition chamber 3 was set to 200 mTorr (about 27 Pa).

Next, the target 7 was irradiated with a laser. The generated vapor was deposited on the surface of the heated alumina porous substrate 5 disposed in front of the target 7. Here, a KrF laser having a wavelength of 248 nm and a pulse width of 30 ns was used. The pulse energy of the laser was 450 mJ / pulse, and its frequency was 30 Hz. The number of pulse irradiations (number of shots) was 30,000. The irradiation time is determined by the total number of irradiations (number of shots) and frequency, and in this case, the number of shots is 30,000 times / 30 Hz, that is, 1000 seconds.
After the laser irradiation treatment, the obtained inorganic porous body is cooled to about room temperature at a rate of 20 ° C./min, the gas atmospheric pressure is increased to about atmospheric pressure, and then taken out from the deposition chamber 3. It was.

(2) Observation of inorganic porous membrane The cross section and surface of the inorganic porous membrane of the inorganic porous body obtained as described above were observed with a field emission scanning electron microscope (FESEM), and the structure and shape thereof were observed. analyzed. The average pore diameter was measured from this photograph.
FIG. 2 shows a 50 × 10 ³ times FESEM photograph of the cross section near the membrane of the inorganic porous material obtained in this example. FIG. 3 shows a cross-sectional FESEM photograph of 100 × 10 ³ times the film portion. As is apparent from FIGS. 2 and 3, it can be seen that the inorganic porous membrane is formed on the surface of the substrate with a substantially uniform thickness. Moreover, the film thickness measured from this photograph was less than 1 μm.
Furthermore, the FESEM photograph of the surface of an inorganic porous membrane is shown in FIG. The magnifications of these photographs are (A) 200 × 10 ³ times, (B) 50 × 10 ³ times, (C) 20 × 10 ³ times, and (D) 5 × 10 ³ times. As is apparent from these photographs, it can be seen that the inorganic porous film is formed in a porous manner by depositing a large number of inorganic materials, that is, clusters, dispersed in a predetermined size. It can also be seen that the inorganic material is uniformly dispersed and has a homogeneous structure. Furthermore, the average pore diameter was about 50 nm.

<Examples 2 to 7>
(1) Manufacture of inorganic porous body The examples described above, except that the heating temperature of the alumina porous substrate was changed from 650 ° C to 30 ° C, 400 ° C, 500 ° C, 550 ° C, 600 ° C, or 800 ° C. A total of six types of inorganic porous membranes were formed on the alumina porous substrate by the same procedure as in 1. However, in Example 2 in which the temperature of the porous alumina substrate was 30 ° C., the number of pulse irradiations (number of shots) was changed to 30000 times and 20000 times.

(2) Observation of inorganic porous membrane Some FESEM photographs of the obtained inorganic porous membrane are shown in FIGS. That is, FIG. 5 is a photograph of the surface of a film 100 × 10 ³ times that of pulse irradiation at a substrate temperature of 400 ° C. FIG. 6 is a photograph of the surface of a 100 × 10 ³ × film obtained by pulse irradiation at a substrate temperature of 550 ° C. FIG. 7 is a photograph of the surface of the film 100 × 10 ³ times larger than that of pulse irradiation at a substrate temperature of 600 ° C. FIG. 8 is a photograph of the surface of the film 100 × 10 ³ times that of the pulse irradiated at a substrate temperature of 650 ° C. Figure 9 is a photograph of the surface of 100 × 10 ³ times the film although the substrate temperature is pulse irradiation at 800 ° C., further FIG. 10 is a photograph of the surface of the 20 × 10 ³ times the film.
Moreover, FIG. 11 is a cross-sectional photograph of the film 100 × 10 ³ times that of the pulse irradiation at a substrate temperature of 550 ° C. FIG. 12 is a cross-sectional photograph of a film of 100 × 10 ³ times that irradiated with a pulse at a substrate temperature of 650 ° C. FIG. 13 is a cross-sectional photograph of a film 100 × 10 ³ times that of pulse irradiation at a substrate temperature of 800 ° C. In addition, Table 1 shows the average pore diameters obtained from these photographs together with the results of Example 1.

As is clear from FIGS. 11 to 13 which are cross-sectional photographs of the film, in any of the examples, regular vapor (cluster) is formed on the porous substrate so that pores oriented in the film thickness direction are formed. It can be seen that a film is formed by deposition. Further, as is apparent from FIGS. 5 to 10 which are surface photographs of the membrane, an inorganic porous membrane is formed almost uniformly on the porous substrate (FIG. 10), and this membrane is vapor ( It can be seen that the (cluster) is formed in a porous structure consisting of a portion where the clusters are accumulated in a columnar shape and pores which are gaps formed between the deposited portions. It can be seen that the size of the columnar deposits decreases as the substrate temperature increases during film formation, that is, the pores also decrease.
Further, from Table 1 that summarizes the average pore diameter of the film with respect to each substrate temperature, it can be seen that the average pore diameter of the film can be controlled by the substrate temperature at the time of film formation. That is, it can be seen that the average pore diameter of the membrane gradually decreases with the substrate temperature.

  The preferred embodiments of the present invention have been described in detail above, but these are only examples and do not limit the scope of the claims. For example, the materials constituting the porous substrate and the inorganic porous film are not limited to those of the above-described embodiments, and various inorganic materials can be used in appropriate combination. Further, the frequency of the pulse laser, the number of irradiations, the temperature, and the irradiation atmospheric pressure can be appropriately selected within the scope of the object of the present invention. In particular, the technology described in the claims includes various modifications and alterations of the above-illustrated embodiments. In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

  The inorganic porous material produced according to the present invention can be applied as a porous material without any particular limitation. In particular, it can be suitably used in applications for separating, purifying, or adsorbing gases and liquids. Moreover, it can use suitably for any use which disperses and uses a catalyst material. Furthermore, a dense film, for example, an ion conductive film formed can be suitably used for other applications, for example, sensors, electrochemical devices, fuel cells (for example, air electrodes), and the like.

It is explanatory drawing which shows typically the apparatus used for the pulse laser ablation deposition method in the Example. FIG. 5 is a FESEM photograph of 50 × 10 ³ times the cross section in the vicinity of a film of an inorganic porous material obtained by pulse irradiation at a substrate temperature of 650 ° C. in one example. ^{3 is} a 100 × 10 ³ times FESEM photograph of the membrane portion of FIG. It is a FESEM photograph of the film | membrane surface of FIG. 3, (A) is a 200x10 ³ times enlarged photograph, (B) is a 50x10 ³ times magnified photograph, (C) is a 20x10 ³ times magnified photograph, (D) is an enlarged photograph of 5 × 10 ³ times. Substrate temperature is 100 × 10 ³ times FESEM photograph of the film surface of the inorganic porous body obtained by pulse irradiation at 400 ° C. In another embodiment. It is a FESEM photograph of 100x10 ³ times the membrane | film | coat surface of the film | membrane of the inorganic porous body obtained by pulse-irradiating at 550 degreeC in base material temperature in another Example. It is a FESEM photograph of 100x10 ³ times of the film | membrane surface of the inorganic porous body obtained by pulse-irradiating at 600 degreeC in base material temperature in another Example. In one Example, it is a FESEM photograph of 100 × 10 ³ times the film surface of the inorganic porous body obtained by pulse irradiation at a substrate temperature of 650 ° C. It is a FESEM photograph of 100x10 ³ times the film | membrane surface of the inorganic porous body obtained by pulse-irradiating at 800 degreeC in base material temperature in another Example. 10 is a FESEM photograph of 20 × 10 ³ times that of FIG. 9. It is a FESEM photograph of 100x10 ³ times the film | membrane cross section of the inorganic porous body obtained by pulse-irradiating at 550 degreeC in base material temperature in another Example. It is a FESEM photograph of 100x10 ³ times the film cross section of the inorganic porous body obtained by performing pulse irradiation at a substrate temperature of 650 ° C in one example. It is a FESEM photograph of 100x10 ³ times the film | membrane cross section of the inorganic porous body obtained by pulse-irradiating at 800 degreeC in base material temperature in another Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... PLD apparatus 3 ... Deposition chamber 5 ... Base material 6 ... Base material holder 7 ... Target

Claims (5)

A method for producing an inorganic porous body comprising an inorganic porous film having an average pore diameter in the range of 5 to 200 nm having a plurality of pores oriented substantially in the film thickness direction on the surface of the porous substrate,
Preparing a target composed of stabilized zirconia and a porous substrate composed of ceramic;
The target and the porous substrate are arranged in a depressurized deposition chamber, and the oxidizing chamber is reduced to 1 to 200 Pa in the deposition chamber.
The target is irradiated with a pulse laser having a frequency in the range of 5 to 500 Hz under the substantially constant temperature condition set in the temperature range of 30 to 800 ° C. in the oxidizing gas atmosphere. Generating vapor and depositing the vapor on a surface of the porous substrate to form the porous film;
Including a method.   The method according to claim 1, wherein the target is irradiated with the pulse laser under a substantially constant temperature condition set within a temperature range of 500 to 800 ° C. 2. The method according to claim 1 or 2, wherein the decompression chamber is decompressed and oxygen gas is introduced in order to form the decompressed oxidizing gas atmosphere.   The method in any one of Claims 1-3 which sets the said oxidizing gas atmospheric pressure to 20-40Pa. The method according to claim 1, wherein a ceramic substrate having a surface roughness (Ra) of 1 × 10 ² μm or less is used as the porous substrate.