Deodorizing catalyst, deodorizing coating, and deodorizing filter

Abstract

To achieve an excellent deodorizing performance in a deodorizing filter over a long term.SOLUTION: A deodorizing catalyst contains δ-type MnO2 and CeO2, and has a structure where CeO2 particles are covered with δ-type MnO2. The δ-type MnO2 covering CeO2 has a mean particle diameter of 20 μm or less, and has a specific surface area of 250 m2 / g or more in terms of BET value.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a deodorizing catalyst, a deodorizing film, and a deodorizing filter that adsorb and decompose odor molecules.

Background Art

[0002] Conventionally, as a deodorizing filter used in an air purifier or a refrigerator, one using a deodorizing catalyst in which δ-type manganese dioxide (MnO2) and cerium oxide (CeO2) are mixed is known (for example, Patent Document 1). δ-type MnO2 has a layered structure and has a property of easily adsorbing odor molecules such as formaldehyde, for example, compared to α-type MnO2 having a small pore diameter forming a tunnel-like structure. This δ-type MnO2 exhibits a deodorizing function (catalytic function) of oxidizing and decomposing the adsorbed odor molecules. And CeO2 functions as a promoter that regenerates the catalytic function of δ-type MnO2 by supplying oxygen to δ-type MnO2.

[0003] In such a deodorizing catalyst, when applied to a deodorizing filter, it is required to be able to exhibit more excellent deodorizing performance over a longer period of time.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made to solve the above problems, and the main problem is to be able to exhibit excellent deodorizing performance over a long period of time in a deodorizing filter.

Means for Solving the Problems

[0006] That is, the deodorizing catalyst according to the present invention contains δ-type MnO2 and CeO2, has a structure in which CeO2 is coated on δ-type MnO2, the average particle diameter of the catalyst having this structure is 20 μm or less, and the specific surface area is 250 m 2 / g or more as the BET value.

[0007] Further, the deodorizing film according to the present invention is characterized by containing the above-described deodorizing catalyst of the present invention and an inorganic binder.

[0008] Furthermore, the deodorizing filter according to the present invention is characterized by comprising a base material and the above-described deodorizing film formed on the surface of the base material.

Effects of the Invention

[0009] According to the present invention configured as described above, excellent deodorizing performance can be exhibited over a long period in the deodorizing filter.

Brief Description of the Drawings

[0010]

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Embodiments for Carrying Out the Invention

[0011] Hereinafter, a deodorizing filter according to an embodiment of the present invention will be described with reference to the drawings.

[0012] (1) Deodorizing filter The deodorizing filter of this embodiment is provided in an air purifier or a refrigerator, and adsorbs and decomposes components such as formaldehyde, ammonia, toluene, trimethylamine, and methyl mercaptan, which are the causes of odors. Specifically, as shown in FIG. 1, this deodorizing filter is a honeycomb filter having a filter base material having a honeycomb structure and a deodorizing film formed on the surface of the filter base material that exhibits a deodorizing function. Note that the deodorizing filter is not limited to a honeycomb filter, and may have any shape as long as a deodorizing film is formed on the surface of the base material.

[0013] (2) Deodorizing film The deodorizing film is a thin film containing particulate deodorizing catalyst and an inorganic binder for supporting the deodorizing catalyst on the filter base material. The deodorizing catalyst of this embodiment is a polar substance mainly composed of a metal oxide, and shows adsorptivity to polar substances such as formaldehyde, ammonia, trimethylamine, and methyl mercaptan among odor molecules, and also has a decomposition function even without heating these substances.

[0014] If the content of the deodorizing catalyst in the deodorizing film is too small, the deodorizing catalyst may be buried in the inorganic binder, and the adsorption and decomposition ability may decrease. Therefore, with the total weight of the deodorizing film being 100% by weight, the content of the deodorizing catalyst is preferably 50% by weight or more, and more preferably 80% by weight or more. On the other hand, if the content of the deodorizing catalyst in the deodorizing film is too high, there is a risk that the deodorizing catalyst cannot be dispersed in the inorganic binder. Therefore, with the total weight of the deodorizing film being 100% by weight, the content of the deodorizing catalyst is preferably 98% by weight or less, and more preferably 97% by weight or less.

[0015] The inorganic binder is composed of, for example, colloidal silica, water glass, calcium silicate, alumina sol, titania sol, silicone oil, metal alkoxide, etc., but is not limited thereto.

[0016] The deodorizing film may further contain activated carbon. Activated carbon can adsorb and retain non-polar substances (specifically toluene) for which the deodorizing catalyst, a polar substance, is less likely to exhibit adsorptivity. In the deodorizing film, it is preferable that the activated carbon particles be present adjacent to the deodorizing catalyst particles. For this purpose, similar to the CeO2 particles, activated carbon may also be used which is not physically mixed but coated with δ-type MnO2 by a crystallization method.

[0017] If the content of the activated carbon is too small, there is a risk that non-polar substances cannot be completely adsorbed and retained and will be re-released before being decomposed. Therefore, with the total weight of the deodorizing film being 100% by weight, the content of the activated carbon is preferably 5% by weight or more, and more preferably 10% by weight or more. On the other hand, if the content of the activated carbon is too high, the amount of odor molecules that the deodorizing catalyst can adsorb decreases, resulting in insufficient decomposition ability of the odor molecules and breakthrough over time, and there is a risk that odors will be released. Therefore, with the total weight of the deodorizing film being 100% by weight, the content of the activated carbon is preferably 20% by weight or less, and more preferably 15% by weight or less.

[0018] The deodorizing film may also contain one or more metal oxides selected from, for example, MgO, FeO, Fe2O3, ZrO2, CuO, NiO, Mn3O4, Co3O4, Al2O3, Y2O3, ZnO, MoO3, IrO2, WO3, W2O3, and TiO2. By containing such metal oxides, the types of decomposable odor molecules can be expanded and the decomposition performance of the odor molecules can be further improved.

[0019] (3) Deodorizing catalyst The deodorizing catalyst is a particulate material containing δ-type manganese dioxide (MnO2) having a layered structure and cerium oxide (CeO2).

[0020] In the deodorizing catalyst of this embodiment, δ-type MnO2 is synthesized by crystal growth on the surface of CeO2 particles, whereby the CeO2 particles are covered (enclosed) by δ-type MnO2, and CeO2 and δ-type MnO2 are firmly bonded (adhered) to each other by the anchor effect.

[0021] The deodorizing catalyst of this embodiment contains δ-type MnO2 having a layered structure with a large interlayer distance, and thus is more likely to take in odor molecules that cause odors compared to the case of containing α-type MnO2 having a small pore diameter of the tunnel type, so that these odor molecules can be more easily adsorbed. Also, by containing CeO2, oxygen can be supplied to δ-type MnO2 that plays a catalytic role, so that the catalytic action of δ-type MnO2 can be regenerated. And the deodorizing catalyst of this embodiment has a structure in which CeO2 is covered (enclosed) by δ-type MnO2, and since these are in contact with each other by the anchor effect, the transfer of oxygen from CeO2 to δ-type MnO2 is likely to occur, and moreover, it is difficult for CeO2 to separate from δ-type MnO2, so that the regeneration of the catalytic function of δ-type MnO2 is promoted and the catalytic performance can be maintained over a long period. Also, if it is δ-type MnO2 having a high BET, oxygen supply can be easily performed up to the inside of MnO2, so that by covering CeO2 with δ-type MnO2, oxygen transfer is possible not only on the surface of δ-type MnO2 but also inside, and the regeneration of the catalytic action can be promoted.

[0022] The fact that CeO₂ has a structure coated with δ-MnO₂ can be confirmed by observations using SEM images and EDX mapping analysis performed on the deodorizing catalyst. An example is shown in FIGS. 2 and 3. As shown in FIG. 2, when the deodorizing catalyst of this embodiment is observed with an SEM image, only δ-MnO₂ can be confirmed, but CeO₂ cannot be confirmed. On the other hand, when the observed location in FIG. 2 is subjected to EDX mapping analysis, as shown in FIG. 3, the presence of δ-MnO₂ can be confirmed. By comparing FIGS. 2 and 3, it can be confirmed that CeO₂ is coated on δ-MnO₂.

[0023] Such a deodorizing catalyst of this embodiment having a structure in which CeO₂ is coated (encapsulated) with δ-MnO₂ can be obtained by adding CeO₂ particles in advance during the synthesis process (crystal growth process) of δ-MnO₂. Specifically, δ-MnO₂ can be obtained by dropping manganese sulfate (MnSO₄) into a potassium permanganate (KMnO₄) solution. By adding CeO₂ particles in advance to the potassium permanganate (KMnO₄) solution before dropping manganese sulfate (MnSO₄), crystals of δ-MnO₂ can be grown on the surface of the CeO₂ particles. As a result, a deodorizing catalyst can be obtained in which CeO₂ particles have a structure coated (encapsulated) with δ-MnO₂, and CeO₂ and δ-MnO₂ are firmly bonded to each other by an anchor effect.

[0024] Rather than physically mixing δ-MnO₂ particles and CeO₂ particles, by growing δ-MnO₂ on the surface of CeO₂ particles, the porous structure of δ-MnO₂ becomes less likely to be broken, and thus, as will be described later, an excellent specific surface area can be obtained.

[0025] Assuming that the total content of δ-MnO₂ and CeO₂ in the catalyst is 100% by weight, the preferred content of each component is as follows.

[0026] If the content of δ-MnO₂ is too low, the surface area for adsorbing odor molecules will be insufficient, and the deodorization and decomposition performance may be insufficient. Therefore, the content of δ-MnO₂ is preferably 90% by weight or more, and more preferably 94% by weight or more. On the other hand, if the content of δ-MnO₂ is too high, the supply of oxygen by CeO₂ will not be sufficient, and the catalytic function may not be regenerated sufficiently. Therefore, the content of δ-MnO₂ is preferably 99.5% by weight or less, and more preferably 96% by weight or less.

[0027] Also, if the content of CeO₂ is too low, the supply of oxygen to δ-MnO₂ will not be sufficient, and the catalytic function may not be regenerated sufficiently. Therefore, the content of CeO₂ is preferably 0.5% by weight or more, and more preferably 4% by weight or more. On the other hand, if the content of CeO₂ is too high, the surface area for adsorbing odor molecules will be insufficient, and the deodorization and decomposition performance may be insufficient. Therefore, the content of CeO₂ is preferably 10% by weight or less, and more preferably 6% by weight or less.

[0028] The preferred average particle diameter of each particle in the deodorizing catalyst is as follows. The average particle diameter can be measured from the particle size distribution by the laser diffraction / scattering method.

[0029] If the average particle diameter of the δ-MnO₂ catalyst coated with CeO₂ is too large, it will be difficult to support the catalyst particles with an inorganic binder, which may cause powder falling during use. Therefore, the average particle diameter of the δ-MnO₂ catalyst coated with CeO₂ is preferably 20 μm or less, and more preferably 10 μm or less. On the other hand, if the average particle diameter of the δ-MnO₂ catalyst coated with CeO₂ is too small, the surface will be covered by the inorganic binder due to the increased catalyst surface area, and sufficient deodorization performance cannot be exhibited. Therefore, the average particle diameter of the δ-MnO₂ particles is preferably 3 μm or more.

[0030] If the average particle size of CeO2 is too large, the contact area with δ-MnO2 will decrease, and there is a risk that sufficient oxygen supply performance cannot be exhibited. Therefore, the average particle size of CeO2 particles is preferably 0.5 μm or less.

[0031] The specific surface area of the deodorizing catalyst is the BET value, 250 m 2 / g or more is preferable, 280 m 2 / g or more is more preferable, 300 m 2 / g or more is even more preferable. The BET value of the specific surface area can be measured from the gas adsorption amount by N2. By setting the specific surface area of the deodorizing catalyst to 250 m 2 / g or more, it is possible to have a sufficient surface area for the adsorption of odor molecules, and it becomes possible to decompose odor molecules with high efficiency.

Examples

[0032] Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited by the following examples, and it is also possible to make modifications within the scope that can conform to the above-mentioned and following gists, and all of them are included in the technical scope of the present invention.

[0033] (Experimental Example 1) A deodorizing catalyst and a deodorizing film were prepared so as to have the compositions shown in Table 1 below (Examples 1 to 4, Comparative Examples 1 to 5). In the composition column of Table 1, "MnO2:CeO2" indicates the weight ratio of MnO2 and CeO2 in the deodorizing catalyst. "MnO2", "CeO2" and "activated carbon" indicate the weight ratios of the respective components in the deodorizing film. The samples of Examples 1 to 4 and Comparative Examples 1 to 4 are deodorizing catalysts and deodorizing films containing δ-MnO2, and the sample of Comparative Example 5 is a deodorizing catalyst and deodorizing film containing α-MnO2. The samples of Examples 1 to 4 and Comparative Examples 1 to 3 were obtained by crystal growth of δ-MnO2 on the surface of CeO2 particles by the method described above, and the sample of Comparative Example 4 was obtained by physically mixing pre-prepared CeO2 particles and δ-MnO2 particles using a mill or the like.

[0034] (Analysis by SEM-EDX) The surface of the deodorizing catalyst powder of each obtained sample was observed by SEM (scanning electron microscope), and the state of each particle was confirmed by performing analysis by EDX mapping. In the deodorizing catalysts of Examples 1 to 4 and Comparative Examples 1 to 3 obtained by crystal growth of δ-MnO2 on the surface of CeO2 particles, as shown in Fig. 3, it was confirmed by EDX mapping that the CeO2 particles were encapsulated by δ-MnO2. Fig. 2 is an SEM image observing the same field of view of the EDX mapping shown in Fig. 3, and it is an observation of the surface of the deodorizing catalyst of Example 4.

[0035] On the other hand, in the deodorizing catalyst of Comparative Example 4 obtained by physically mixing pre-prepared CeO2 particles and δ-MnO2 particles using a mill or the like, it was confirmed that the CeO2 particles were not encapsulated by δ-MnO2 but adhered to the surface of the δ-MnO2 particles as shown in the SEM image of Fig. 4. This state is also clear from Fig. 5 obtained by observing the field of view of Fig. 4 by EDX mapping.

[0036] (Measurement of formulation) The mixing ratio of CeO2 and MnO2 in the deodorizing catalyst of each obtained sample, and the mixing ratio of CeO2, MnO2, and activated carbon in the deodorizing film were measured by performing quantitative analysis of Mn and Ce using XPS (X-ray Photoelectron Spectroscopy) (KRATOS ULTRA2 manufactured by Shimadzu Corporation). The blending amount of activated carbon was estimated from the charged amount.

[0037] (Measurement of BET value) The specific surface area (BET value) of each sample was measured from the adsorption curve in the range of relative pressure p / p0 = 0.0 to 0.20 of the N2 adsorption isotherm measured at 298 K using a gas / vapor adsorption measurement apparatus (BELSORP-max II manufactured by Microtrac BEL Co., Ltd.). (Reference: JIS Z 8830)

[0038] (Measurement of particle size distribution) The particle size distribution of the δ-MnO2 catalyst coated with CeO2 for each sample was measured by a laser diffraction particle size distribution measuring device (SALD-2300, manufactured by Shimadzu Corporation) and image observation by SEM (Scanning Electron Microscope) (JSM-IT800, manufactured by JEOL Ltd.).

[0039] For each of the obtained samples, the deodorizing performance and lifespan were evaluated. The evaluation methods are as follows.

[0040] (Deodorizing performance evaluation) Using a honeycomb filter with a deodorizing film formed on the surface for each sample, the deodorizing performance against odor molecules targeted by filters for air purifiers (formaldehyde, ammonia, toluene) and odor molecules targeted by filters for refrigerators (trimethylamine, methyl mercaptan) was evaluated.

[0041] Specifically, a filter was installed in a 500 L chamber. After injecting a predetermined amount of measurement gas into the chamber, the deodorizing performance was measured using a detector tube for the measurement gas. Then, for each odor molecule, the residual rate (%) was calculated as the ratio of the concentration after 60 minutes to the concentration after 0 minutes (initial concentration). Samples with a residual rate of 20% or less were rated as "〇", those with a residual rate of more than 20% and less than 60% were rated as "△", and those with a residual rate of 60% or more were rated as "×". Samples with an evaluation of "△" or "×" for both the odor molecules targeted by air purifiers and the odor molecules targeted by refrigerators were given an overall deodorizing performance evaluation of "×", and other samples were given an overall deodorizing performance evaluation of "〇". The results are shown in Table 1.

[0042] (Lifespan evaluation) The lifespan of the honeycomb filter with the deodorizing film formed on the surface of each sample was evaluated. Specifically, the filter was installed in a 500 L chamber. After injecting a predetermined amount of the measurement gas into the chamber, the first deodorization rate was measured using a detector tube for the measurement gas. After the test, as a regeneration operation, ventilation of the filter by fan operation was performed for 1 hour. This operation was defined as one cycle, and this was carried out for 20 cycles. Then, the lifespan, which is the ratio of the 20th deodorization rate (%) to the first deodorization rate (%), was calculated. Those with a numerical value of 60% or more were marked as "〇", those exceeding 40% and less than 60% were marked as "△", and those 40% or less were marked as "×". The results are shown in Table 1.

[0043] (Comprehensive Judgment) And those with both the deodorization performance evaluation and the lifespan evaluation being "〇" were given a comprehensive judgment of "〇" (good). On the other hand, those with a "△" evaluation or an "×" evaluation in either the deodorization performance evaluation or the lifespan evaluation were given a comprehensive judgment of "×" (bad).

[0044] [Table 1]

[0045] As can be seen from the results in Table 1, CeO2 has a structure encapsulated in δ-type MnO2. The average particle diameter of the catalyst having this structure is 20 μm or less, and further, the deodorizing filters (Examples 1 to 4) prepared using a deodorizing catalyst with a specific surface area of 250 m 2 / g or more as the BET value were confirmed to have excellent results in both the deodorization performance evaluation and the lifespan evaluation. Note that the deodorizing filter of Example 4 has an "×" evaluation for the deodorization performance with respect to toluene, which is due to the deodorizing film not containing activated carbon, a non-polar substance.

[0046] On the other hand, in Comparative Examples 1 to 5, excellent results were not obtained in either or both of the deodorization performance evaluation and the lifespan evaluation.

[0047] In Comparative Example 1, the life evaluation is "×". This is presumably because the catalyst does not contain CeO2, so oxygen cannot be supplied to δ-MnO2 that has adsorbed and decomposed odor molecules.

[0048] In Comparative Example 2, the deodorizing performance evaluation is "×". This is presumably because the content of δ-MnO2 in the deodorizing catalyst is low, resulting in the overall specific surface area (BET value) being less than 250 m 2 / g.

[0049] In Comparative Example 3, the particle size of δ-MnO2 in the prepared catalyst was too large, resulting in poor slurry dispersibility and the inability to form a deodorizing film on the surface of the filter.

[0050] In Comparative Example 4, the deodorizing performance evaluation is "×". This is presumably because physically mixing δ-MnO2 particles and CeO2 particles damaged the porous structure of δ-MnO2, resulting in a decrease in the specific surface area (BET value) to 250 m 2 / g or less. Also, in Comparative Example 4, the life evaluation is "×". This is presumably because physically mixing δ-MnO2 particles and CeO2 particles did not firmly adhere them, and when slurried, the CeO2 particles separated from the MnO2 particles, so the catalytic activity effect of CeO2 could not be maintained.

[0051] In Comparative Example 5, the deodorizing performance evaluation is "×". This is presumably because using α-MnO2 with a small pore diameter and a tunnel-like structure makes it difficult to capture odor molecules.

[0052] In this experimental example, by using a δ-MnO₂ catalyst coated with CeO₂, it was revealed that for several odor molecules (specifically, formaldehyde, ammonia, trimethylamine), decomposition proceeds at room temperature without heating according to the reaction formula shown in Fig. 6. Also, by growing δ-MnO₂ crystals on CeO₂ to obtain a catalyst in which CeO₂ is supported on δ-MnO₂ (CeO₂ is encapsulated in δ-MnO₂), as shown in Fig. 7, there was a new academic discovery regarding the decomposition principle of odor molecules (specifically, ammonia, toluene, trimethylamine, and methyl mercaptan). Details are shown in Fig. 7.

[0053] (Experimental Example 2) In Experimental Example 2, the effect of the deodorizing performance on HCHO by coating CeO₂ with δ-MnO₂ was confirmed.

[0054] Specifically, as shown in Fig. 8, two types of deodorizing catalyst samples with different manufacturing methods were prepared, and for each, a deodorizing test using HCHO was conducted. One deodorizing catalyst sample was prepared by growing δ-MnO₂ crystals on the surface of CeO₂ particles (described as the "bonding method"), and CeO₂ was coated with δ-MnO₂. The other deodorizing catalyst sample was obtained by physically mixing CeO₂ particles and δ-MnO₂ particles using a mill or the like (described as the "blending method"), and CeO₂ was not coated with δ-MnO₂. These two types of catalyst particle samples had the same specific surface area and the same weight ratio of CeO₂ to δ-MnO₂. Also, the deodorizing tests were all conducted at the same temperature (room temperature). More specific test conditions and material specifications are as described in Fig. 8.

[0055] As can be seen from Fig. 8, under the conditions of the same specific surface area, the same weight ratio of CeO₂ to δ-MnO₂, and the same test temperature, by coating CeO₂ with δ-MnO₂, it was confirmed that the oxygen supply efficiency by CeO₂ was improved, and the deodorization rate and the decomposition effect of HCHO exhibited high performance even after repeated tests.

[0056] (Experimental Example 3) In Experimental Example 3, the performance of promoting regeneration by irradiating the catalyst particles with UV-C was confirmed. Specifically, using a honeycomb filter with the deodorizing film of the present invention formed on the surface, the effect of promoting decomposition by light irradiation was confirmed. For example, the deodorizing performance of the filter for refrigerators against odor molecules (trimethylamine) was repeatedly evaluated using a UV-C lamp (Daiichi Sankyo Denki, 8W). Specifically, the filter was installed in a 100 L chamber, a predetermined amount of the measurement gas was injected into the chamber, and then the deodorizing performance was measured using a detector tube for the measurement gas. Then, for trimethylamine, the deodorization rate (%) was calculated from the ratio of the concentration after 30 minutes to the concentration after 0 minutes (initial concentration), and the deodorization rates during repeated evaluations were plotted. The detailed evaluation conditions and test results are shown in Fig. 9.

[0057] As shown in Fig. 9, when the deodorization rates were compared with or without UV-C irradiation for 1 hour after the performance evaluation (Fan stop was a common condition), in the evaluation with UV-C irradiation for 1 hour, there was a strong tendency to maintain the deodorizing performance even when the deodorization rate was repeated, and it was confirmed that the performance recovered due to the promotion of decomposition.

[0058] Fig. 10 shows the current consideration of the principle of promoting the regeneration of the catalyst by irradiation with UV light. Since δ-MnO2 has a narrower band gap than other structures (α, β, γ), it has high activity as a photocatalyst. That is, since δ-MnO2 also has high photocatalytic activity, ·OH can be generated by irradiating with UV. Then, as shown in Equation 1 in Fig. 10, the generated ·OH reacts with TMA and the decomposition proceeds. In addition, since the oxidative decomposition reaction at room temperature shown in Equation 2 also proceeds accordingly, it is considered that the decomposition of TMA (trimethylamine) was promoted.

Claims

1. δ-MnO ２ and CeO ２ and contains CeO ２ is coated with δ-MnO ２ to form a structure, δ-MnO ２ has an average particle diameter of 20 μm or less, A deodorizing catalyst having a specific surface area of 250 m ２ / g or more in terms of the BET value.

2. δ-MnO ２ with a content of 90 wt% or more and 99.5 wt% or less, CeO ２ The deodorizing catalyst according to claim 1, wherein the content of ２ is 0.5% by weight or more and 10% by weight or less.

3. CeO ２ -coated δ-MnO ２ The deodorizing catalyst according to claim 1 or 2, wherein the average particle diameter of ２ is 20 μm or less.

4. A deodorizing film containing the deodorizing catalyst according to claim 1 or 2 and an inorganic binder.

5. The deodorizing film according to claim 4, further containing activated carbon.

6. MgO, FeO, Fe ２ O ３ 、ZrO ２ 、CuO, NiO, Mn ３ O ４ 、Co ３ O ４ 、Al ２ O ３ 、Y ２ O ３ 、ZnO, MoO ３ 、IrO ２ 、WO ３ 、W ２ O ３ and TiO ２ The deodorant film according to claim 4, further containing one or more selected from

7. A deodorizing filter having a substrate and the deodorizing film according to claim 4 formed on the surface of the substrate.

8. The deodorizing filter according to claim 7, wherein the substrate has a honeycomb structure.

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