JPH09108574A - Phtocatalyst honeycomb structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalyst honeycomb structure which has a large effective surface area which demonstrates a purification function and a good purification capacity. SOLUTION: A photocatalyst honeycomb structure 1 in which a photocatalyst 2 is supported on a honeycomb carrier 10 having honeycomb cells 11. The pitch of the honeycomb cells 11 is 0.5-1.5mm. It is preferable that the effective surface area of the honeycomb carrier is 20cm<2> /cm<3> or more and the thickness of a honeycomb wall is less than 0.5mm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a photocatalyst honeycomb structure used in a device for purifying air, water and the like.

[0002]

As a device for purifying air, water, etc.,
There is a purification device that uses a photocatalyst such as titania (TiO ₂ ). The photocatalyst exerts a strong redox action upon being irradiated with light such as ultraviolet rays, decomposes organic substances contained in substances to be purified such as air and water, and prevents propagation of various bacteria. Therefore, a purification device using a photocatalyst can be used for a longer period of time than a purification device of a filtration type or an adsorption type, which collects organic substances without decomposing them, and is expected to be used in a wider range.

In a purification device using such a photocatalyst, a photocatalyst structure in which a photocatalyst is carried on a carrier is used.
As a conventional photocatalyst structure, for example, JP-A-2-107
As disclosed in Japanese Patent No. 339, there is a photocatalyst honeycomb structure in which a photocatalyst is supported on a honeycomb carrier.

[0004]

However, the above-mentioned conventional photocatalyst honeycomb structure has the following problems. That is, conventionally, a honeycomb carrier having a relatively large honeycomb cell has been used as a honeycomb carrier for supporting a photocatalyst. Therefore, the surface area of the honeycomb cells carrying the photocatalyst is limited, and the effective surface area for exerting the purifying action (purifying effective surface area) cannot be sufficiently increased. Therefore, in the conventional photocatalyst honeycomb structure,
There was a limit to the improvement of purification performance.

On the other hand, it is considered that the purification effective surface area of the honeycomb cells is increased by making the honeycomb cells of the honeycomb carrier finer and increasing the number thereof.
However, simply making the honeycomb cells fine may cause the inside of the honeycomb cells to be clogged by the photocatalyst when the photocatalyst is supported. Therefore, rather,
When the photocatalyst is supported, the above-mentioned effective surface area for purification is reduced and the purification performance is deteriorated.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a photocatalyst honeycomb structure having a large purification effective surface area which exhibits a purification action and excellent purification performance.

[0007]

According to the invention of claim 1, in a photocatalyst honeycomb structure in which a photocatalyst is carried on a honeycomb carrier having honeycomb cells, one pitch of the honeycomb cells is 0.5 to 1.5 mm. It is a featured photocatalyst honeycomb structure.

What is most noticeable in the present invention is that one pitch of the honeycomb cells is 0.5 to 1.5 mm, and the photocatalyst is supported without clogging the honeycomb cells. .

1 pitch of the above honeycomb cells is 0.5 mm
When it is less than 1, there is a problem that the clogging of the honeycomb cell is likely to occur, while when it exceeds 1.5 mm, it is difficult to increase the purification effective surface area of the honeycomb cell as compared with the conventional case. There is.

The above-mentioned honeycomb cell penetrates through the front and back of the honeycomb carrier in the state where the photocatalyst is carried, and is configured so that gas or liquid as the substance to be purified and light such as ultraviolet rays can be conducted. Examples of the photocatalyst include titania (TiO ₂ ) and cadmium sulfide (Cd).
S), tungsten oxide (WO ₃ ) or the like can be used.

Next, the operation and effect of the present invention will be described.
In the photocatalyst honeycomb structure of the present invention, one pitch of the honeycomb cells has the above specific dimension. Therefore, the honeycomb carrier has a larger number of honeycomb cells than the conventional one, and has a large purification effective surface area for carrying a photocatalyst and exhibiting a purification action. Therefore, the contact area between the photocatalyst and the object to be purified is increased compared to the conventional one, and high purification performance can be obtained.

Therefore, according to the present invention, it is possible to obtain a photocatalyst honeycomb structure having a large purification effective surface area which exhibits a purification action and excellent purification performance.

Next, the catalyst honeycomb structure of the present invention is manufactured as follows. First, a honeycomb carrier having honeycomb cells with the above-mentioned specific dimensions is prepared. Further, a catalyst slurry containing the photocatalyst in an amount of 50% by weight or less and having a relatively low viscosity is prepared.

Next, the catalyst slurry is uniformly coated on the honeycomb carrier. Immediately after this coating, the excess catalyst slurry adhered to the honeycomb cells and part of the honeycomb cells became clogged. Therefore, the following special process is taken.

That is, after the coating step, the excess catalyst slurry is sucked and removed by the suction removing device. As a result, in the honeycomb carrier, the catalyst slurry spreads evenly and evenly on the honeycomb cell surface, and clogging is eliminated. Then, by heating and drying, the photocatalyst was uniformly supported on the surface of the honeycomb cell without clogging.
The photocatalyst honeycomb structure is obtained.

Next, as in the invention of claim 2, in addition to the condition of one pitch of the honeycomb cells, it is preferable that the purification effective surface area of the honeycomb carrier is 20 cm ² / cm ³ or more. As a result, the purification performance can be improved more reliably. The upper limit is preferably 50 cm ² / cm ³ or less for reasons such as an increase in pressure loss. The above-mentioned effective surface area for purification means the wall surface area per unit volume inside the honeycomb carrier.

Next, apart from the inventions of claims 1 and 2,
As in the invention of claim 3, the purification effective surface area is 20 cm ² / cm regardless of the value of one pitch of the honeycomb cells.
There are photocatalyst honeycomb structures that are ³ or more. In this case, a sufficiently large purification effective surface area of 20 cm ² / cm ³ can be obtained, so that the contact area between the photocatalyst and the substance to be purified is increased as compared with the conventional case. Therefore, high purification performance can be obtained.
In addition, the same effect as the invention of claim 1 can be obtained.

To manufacture the photocatalyst honeycomb structure of the present invention, for example, the surface of the honeycomb wall is corrugated to increase the surface area without reducing the pitch of the honeycomb cells. As a result, the effective cleaning surface area of the honeycomb carrier is reduced to 2
It can be 0 cm ² / cm ³ or more. The upper limit of the effective surface area for purification is 5 due to reasons such as increased pressure loss.
It is preferably 0 cm ² / cm ³ or less.

Next, as in the invention of claim 4, the thickness of the honeycomb wall of the honeycomb carrier is preferably less than 0.5 mm. As a result, the effective purification surface area of the honeycomb carrier can be further increased. The thickness of the honeycomb wall is more preferably 0.2 mm or less. Further, the lower limit is preferably 0.05 mm or more for the reason of maintaining the structural strength of the honeycomb carrier and suppressing the manufacturing cost.

Next, according to the invention of claim 5, the specific surface area of the photocatalyst supported on the honeycomb carrier is 100.
It is preferably at least m ² / g. As a result, the contact area between the photocatalyst and the substance to be purified is further increased, and the purification performance can be further improved. More preferably, 30
It is preferably 0 m ² / g or more. The larger the specific surface area is, the more preferable. For example, 500 m ² / g is preferably as large as possible.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 A photocatalyst honeycomb structure according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the photocatalyst honeycomb structure 1 of the present example has a disk shape, and the photocatalyst 2 (FIG. 2) is carried on the honeycomb carrier 10 having the honeycomb cells 11.

As shown in FIGS. 1 and 2, the honeycomb carrier 10 has one pitch (P) 1.2 of the honeycomb cells 11.
A cordierite honeycomb carrier having a thickness of 7 mm, a thickness (T) of the honeycomb wall 12 of 0.18 mm, an outer diameter (D) of 108 mmφ, and a length (L) of 10 mm is used. Also, photocatalyst 2
For this, anatase type titania (ST-10 manufactured by Ishihara Sangyo) having a specific surface area of 200 m ² / g or more is used. The effective cleaning surface area of the photocatalyst honeycomb structure of this example is 27 cm ² / cm ³ .

Next, in manufacturing the photocatalyst honeycomb structure 1, 38% by weight of the photocatalyst, 2% by weight of silica sol as an inorganic binder and 60% by weight of water are mixed for 30 minutes to prepare a catalyst slurry. obtain.

Next, the honeycomb carrier 10 is immersed in the above catalyst slurry for 30 seconds to adhere the catalyst slurry to the honeycomb cells 11 of the honeycomb carrier 10. Then, as shown in FIG. 3, a suction device 3 is used to suck and remove the excess catalyst slurry adhering to the honeycomb carrier 10.

As shown in FIG. 3, the suction device 3 has a suction port 31 connected to a suction device 32 and a suction port 3.
It is composed of guides 33 provided before and after 1. Suction port 3
In No. 1, in order to obtain a suction force sufficiently exceeding the surface tension of the slurry, the groove width (S) is formed into a narrow groove shape of about 2.6 mm, and the suction force is locally concentrated.

In order to prevent the catalyst slurry adhering to the suction port 31 from drying and blocking the suction port 31, the height of the suction port 31 is set to the same height as the guides 33 provided on the left and right sides thereof. It is always in contact with the honeycomb carrier. As a result, the tip of the suction port 31 is
The contact state with the moist catalyst slurry is always obtained, and the above problems due to drying can be prevented.

Next, the honeycomb carrier on which the catalyst slurry was evenly and uniformly attached was heated to a temperature of 500 by using an electric furnace.
Heat treatment is performed at 1 ° C. for 1 hour to bake the inorganic binder and fix the photocatalyst. As a result, the photocatalyst honeycomb structure 1 is obtained.

Next, in order to confirm the effect of the photocatalyst honeycomb structure 1 of this example, the purification performance was measured using a black light. As a honeycomb carrier, for comparison,
Comparative product 1 using a wire mesh of # 20 mesh having a cleaning effective surface area of about 5 cm ² / cm ³ and a cleaning effective surface area of about 1
Comparative product 2 using a sponge mesh of 0 cm ² / cm ³ was also measured in the same manner.

The purification performance was measured by measuring a 2 cm square photocatalyst honeycomb structure and 6 in a sealed 0.8 liter container.
The acetaldehyde concentration was measured after adding 00 PPM of acetaldehyde and irradiating it with a UV lamp (0.5 W / cm ² ) for 60 minutes.

The measurement results are shown in FIG. In Fig. 4, the horizontal axis shows the type of the DUT and the vertical axis shows the purification performance. As is known from FIG. 4, the product of the present invention having a large effective surface area for purification showed excellent purification performance about twice that of Comparative product 1 and about 1.5 times that of Comparative product 2. As described above, according to this example, it is possible to obtain a photocatalyst honeycomb structure having a large purification effective surface area that exhibits a purification action and excellent purification performance.

Embodiment 2 In this embodiment, the effective cleaning surface area and the porosity were measured by changing the honeycomb cell pitch in Embodiment 1 variously. Furthermore, the specific surface area of the supported photocatalyst was changed and the change in the purification rate was measured.

First, the relationship between the pitch of the honeycomb cells and the effective purification surface area will be described. In this measurement, the photocatalyst honeycomb structure having the same configuration as that of the first embodiment except for the pitch of the honeycomb cells was used. The effective surface area was measured by a method of measuring the BET-surface area by N ₂ gas adsorption with a specific surface area meter using a sample that was vacuum degassed at a temperature of 100 ° C. for 2 hours.

The measurement results are shown in FIG. In FIG. 5, the horizontal axis represents one pitch of honeycomb cells, and the vertical axis represents the effective surface area for purification. As is known from FIG. 5, the effective cleaning surface area became extremely large and exceeded 20 cm ² / cm ³ in the range where the one pitch of the honeycomb cells was 1.5 mm or less.

Next, the relationship between the value of one pitch of the honeycomb cells and the porosity of the honeycomb carrier will be described. Here, the porosity of the honeycomb carrier means the ratio of the area of the voids in the cross section. This porosity greatly affects the pressure loss when the substance to be purified is passed through the photocatalyst honeycomb structure. In particular, when the porosity is less than 60%, it becomes a serious problem when used as a purification device. In addition, in this measurement, a photocatalyst honeycomb structure having the same configuration as that of the first embodiment except the pitch of the honeycomb cells was used. The porosity was calculated by the following formula by measuring the cell pitch (P) and wall thickness (T) of the honeycomb carrier at 40 points. (P-T) ² / P ² × 100 (%)

The measurement results are shown in FIG. In FIG. 6, the horizontal axis represents one pitch of the honeycomb cells, and the vertical axis represents the porosity of the honeycomb carrier. As is known from FIG. 6, when the one pitch of the honeycomb cells is within a range of 1.5 mm or less, the porosity is 6
It can be seen that the pressure loss can be suppressed to a very low level, exceeding 0%.

Next, the measurement results of the purification rate with respect to the specific surface area of the supported photocatalyst will be described. In this measurement, a photocatalyst honeycomb structure having the same configuration as that of the first embodiment except for the specific surface area of the photocatalyst was used. To measure the purification rate,
The method was the same as the method for measuring the purification performance in the first embodiment.

The measurement results are shown in FIG. In FIG. 7, the horizontal axis shows the specific surface area of the photocatalyst and the vertical axis shows the purification rate. As is known from FIG. 7, when the specific surface area of the photocatalyst is 100 m ² / g or more, the purification rate exceeds 50%, which shows excellent purification performance. Further, it can be seen that when it is 300 m ² / g or more, the purification rate shows an extremely excellent purification performance exceeding 90%.

Embodiment 3 In this example, as shown in FIGS. 8 to 10, a bath purifying device 6 for purifying bath water using a photocatalyst honeycomb structure will be described. As shown in FIG. 8, the photocatalyst honeycomb structure 5 incorporated in the bath cleaning device 6 has a rectangular parallelepiped shape and has the honeycomb carrier 5 having the honeycomb cells 51.
0 carries a photocatalyst 2 (see FIG. 2). In addition, the dimensions, manufacturing method, type of photocatalyst, and the like are the same as those of the disk-shaped photocatalyst honeycomb structure 1 of the first embodiment.

As shown in FIGS. 9 and 10, the bath purifying device 6 includes an outer tube portion 62, an ultraviolet lamp 61 arranged at the center of the outer tube portion 62, the ultraviolet lamp 61 and the outer tube 62.
And the four photocatalyst honeycomb structures 5 arranged so as to surround the periphery of the ultraviolet lamp. An outer water channel 65 is formed between the outer tube portion 62 and the photocatalyst honeycomb structure 5, and an inner water channel 66 is formed between the photocatalyst honeycomb structure 5 and the ultraviolet lamp 61.

The outer water channel 65 is filled with granular bare rock grains for biological purification. Further, in the lower part of the outer tube portion 62, a water flow chamber 630 having a water flow inlet 63 for receiving the bath water and a water inlet 64 communicating with the external water passage 65 is provided. Further, a water outlet 67 for returning the purified water to the bath is provided on the upper portion of the outer cylinder 62.

The water outlet 63 is connected to the bath 70 via a water supply pipe 71 and a water supply pump 72, while the water outlet 67 is connected to the bath 70 via a return pipe 73.

Next, when purifying water using the bath purifying device 6, first, the water 8 in the bath 70 is fed into the flush chamber 630 by the water pump 72. The water sent in flows into the outer water channel 65 through the water inlet 64. Then, the water passes through the photocatalyst honeycomb structure 5 and repeatedly moves from the outer water channel 65 to the inner water channel 66 and from the inner water channel 66 to the outer water channel 65, and finally from the outer water channel 65 to the water outlet 67 and the return pipe 73. To return to the bath 70.

The water in the bath purification device 6 is biologically purified by the bare rock grains 69 when it exists in the outer water channel 65, and when it passes through the photocatalyst honeycomb structure 5, it is irradiated by the ultraviolet lamp 61. The photocatalyst 2 exhibits a strong redox action, and organic substances in water are decomposed and removed.

Further, the photocatalyst honeycomb structure 5 has excellent purification performance as shown in the first embodiment. Therefore, the water purified by the bath purification device 6 is purified at a high purification rate, and a clean bath can always be maintained.

[Brief description of the drawings]

FIG. 1 is a perspective view of a photocatalyst honeycomb structure according to a first embodiment.

FIG. 2 is a partially enlarged view of the photocatalyst honeycomb structure of the first embodiment.

FIG. 3 is an explanatory diagram showing a suction / removal device according to the first embodiment.

FIG. 4 is an explanatory diagram showing purification performance in the first embodiment.

FIG. 5 is an explanatory view showing the relationship between the pitch of honeycomb cells and the effective purification surface area in the second embodiment.

FIG. 6 is an explanatory diagram showing the relationship between the pitch of the honeycomb cells and the porosity of the honeycomb carrier in the second embodiment.

FIG. 7 is an explanatory diagram showing the relationship between the specific surface area of the photocatalyst and the purification rate in the second embodiment.

FIG. 8 is a perspective view of a photocatalyst honeycomb structure 5 according to the third embodiment.

FIG. 9 is an explanatory diagram showing a configuration of a bath purifying apparatus according to the third embodiment.

FIG. 10 is a cross-sectional view of the bath cleaning device according to the third embodiment.

[Explanation of symbols]

 1,5. . . Photocatalyst honeycomb structure, 10, 50. . . Honeycomb carrier, 11, 51. . . Honeycomb cell, 2. . . Photocatalyst, 3. . . Suction removal device, 6. . . Bath purifier, 61. . . UV lamp,

Claims (5)

[Claims] 1. A photocatalyst honeycomb structure in which a photocatalyst is supported on a honeycomb carrier having honeycomb cells, wherein one pitch of the honeycomb cells is 0.5 to 1.5 mm. 2. The photocatalyst honeycomb structure according to claim 1, wherein the effective purification surface area of the honeycomb carrier is 20 cm ² / cm ³ or more. 3. A photocatalyst honeycomb structure in which a photocatalyst is carried on a honeycomb carrier having honeycomb cells, wherein the effective purification surface area of the honeycomb carrier is 20 cm ² / cm.
^A photocatalyst honeycomb structure characterized by being ³ or more. 4. The method according to claim 1, wherein:
The photocatalyst honeycomb structure, wherein the honeycomb wall of the honeycomb carrier has a thickness of less than 0.5 mm. 5. The method according to claim 1, wherein:
The photocatalyst honeycomb structure, wherein the specific surface area of the photocatalyst supported on the honeycomb carrier is 100 m ² / g or more.