JPH0394814A - Deodorizing method with photocatalyst - Google Patents

Abstract

PURPOSE:To allow the decomposition reaction of a malodor with a photo- catalyst to proceed efficiently by corrugating the photocatalyst supporting a semiconductor, introducing gas contg. the malodor and irradiating the photocatalyst with UV. CONSTITUTION:Alumina-silica ceramic paper is corrugated at a specified height of corrugation and a specified pitch and a titania sol is impregnated into the corrugated paper, dried and heat-treated to support titanium oxide. The resulting photocatalyst 1 is set on the bottom of a reactor and air contg. a malodor is discharged from a cylinder. A UV lamp 3 is then lighted to irradiate the photocatalyst with UV. Since the photocatalyst is corrugated, a turbulent flow is generated to increase the efficiency of contact of the photocatalyst with the gas and the amt. of the photocatalyst irradiated with UV is increased even in a narrow space.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is useful for eliminating bad odors (cooking odors, food odors, etc.) in homes and offices.
This invention relates to a deodorizing method using a photocatalyst, which is used to deodorize tobacco odors, body odors, pet and toilet odors, etc.

Conventional technology The components of bad odors (cooking odor, food odor, tobacco odor, bed and toilet odor, etc.) that occur in homes and offices are nitrogen compounds (ammonia, amines, indole, skatole, etc.) and sulfur compounds (hydrogen sulfide).・Methylmercabutane・
methyl sulfide, methyl disulfide, dimethyl disulfide, etc.), aldehydes (formaldehyde, acetaldehyde, etc.)
, ketones (acetone, etc.), alcohols (methanol, ethanol, etc.), fatty acids, and aromatic compounds.

Conventionally, methods for deodorizing such bad odors include a method of causing a chemical reaction between a malodorous substance and a drug, a method of masking the malodorous substance with an air freshener, a method of adsorbing the malodorous substance with activated carbon or zeolite, etc. There are ways to use them in combination.

However, with these methods, when the deodorizing ability deteriorates or the material is used up, it is necessary to replace it with a new one.

In particular, with respect to adsorbents and deodorizers that do not change in appearance even when their deodorizing performance is exhausted, users would replace them when they felt that their deodorizing performance had deteriorated, indicating that it was time to replace them. However, this replacement work was troublesome.

Therefore, attempts have been made to deodorize using photocatalytic action. This method irradiates semiconductors such as titanium oxide with ultraviolet rays, and uses the semiconductors excited by this to oxidize and decompose organic substances.It is used to decompose all kinds of evil substances, including aldehydes, which are difficult to deodorize with activated carbon. There is.

Problems to be Solved by the Invention Factors that determine the performance of the photocatalyst described above include the intensity of ultraviolet rays, the amount of catalyst, and the contact effect between gas and catalyst. Therefore, the amount of catalyst may be increased, or guide fins may be installed in order to increase the effectiveness of contact between the foul odor and the catalyst.

However, with this conventional method, the guide fins block the ultraviolet rays, creating areas where the ultraviolet rays are weak or in shadows.
The problem is that the reaction does not progress or, conversely, deep intermediate products are produced, making it difficult to increase the deodorization rate.

The present invention improves the above-mentioned conventional features; 1! The purpose of this invention is to provide a photocatalytic deodorizing method that can efficiently proceed with the photocatalytic decomposition reaction of malodors.

In order to achieve the object described in step F for solving the problems, the present invention provides a process in which a corrugated plate-shaped catalyst supporting a semiconductor and a gas containing animal odor are present. This is a deodorizing method using a photocatalyst 1 in which the catalyst is irradiated with ultraviolet rays.By making the shape of the catalyst into a corrugated plate, turbulent flow occurs on the catalyst surface, which increases the contact efficiency with the gas. In addition, the amount of catalyst exposed to ultraviolet rays increases even in a narrow space, and the amount of catalyst irradiated with ultraviolet rays increases.

Embodiments Hereinafter, embodiments of the present invention will be described using FIGS. 1, 2, and 3.

FIG. 1 is a perspective view of a wave-shaped photocatalyst in which titanium oxide is suspended. This configuration has a thickness of 0. A 5 mm -i'lumiwosiri ceramic beaver with a wave height of 4 mm,
Molded to a pitch of about 71, it looks great! ．． After being impregnated with a final sol and dried, it is heat-treated at a temperature of 400°C to 70°C to support titanium oxide. In this example, the amount of supported titane oxide was 400 g/d. Figure 2 shows a flow measuring device for measuring the decomposition rate in a catalytic reaction bath. 5+++m, length 1
A photocatalyst 2a4 of 20tlIm was set, and a quartz plate window 2k) was installed on the opposite side. An ultraviolet light moon 3 is provided at the center of the window 21). 2c and 2d are baffle plates, and both have a gap of 5 mm in the F direction. 4 is a cylinder containing foul-smelling gas, and 5 is an empty cylinder. , 6a and 6b are regulators that adjust the JE force of the gas discharged from the bottom, 7a and 7h are flow jet regulators, and 8 is a mixer for mixing two types of gas without uniformity. It is a vessel.

9 is a Tamakata cock that switches between the bypass side and the reaction side; 1
0 is the piping that connects each element, and is made of glass, fluorine resin, stainless steel, etc. , 11・12・1
3 is a rubber stopper for gas sampling. A germicidal lamp GI, 10 with a power consumption of 10b1 was used as the ultraviolet lamp 3, and was set so that the intensity of the ultraviolet light on the surface of the photocatalyst 2a was 3.0 mW (at a wavelength of 250 nm). Also, the total flow rate of gas is 2e. The flow rate regulators 7a and 7b were adjusted so that /' tn i n.

Next, a method of operating this flow-type measuring device will be explained. After setting the photocatalyst 2a in the reactor 2{J, opening the three-way screw 9 to the bypass side, open the holes 4 and 5 to the bong to let out the Akasagi gas and air, and then the flow rate regulator 7; Adjust 7b appropriately and leave it for a while. Once the gas flow has stabilized, samble the gas with a syringe from Gomu Katsura ↓1, analyze it with Gask ``] matography, and measure the concentration.

When the mixed gas stabilizes at the set flow rate and set concentration by adjusting the flow rate regulators 7a and 71), the ultraviolet lamp 3 is turned on and the photocatalyst 2a is irradiated with ultraviolet light for 5 minutes. Next, switch the three-way cock 9 to open to the reaction side and leave it for 5 minutes. Thereafter, the rubber stoppers 12 and 13 are injected and compressed using syringes, respectively, and concentration analysis is performed using gas sunset chromatography at 10-minute intervals for 120 minutes. By substituting the gas concentration of "This person 1" and output 1-1 into the following equation, the decomposition rate m of malodorous gas by the photocatalyst 2a is determined.

m = (1-b/a) rate.

Below, the results of comparing the decomposition rates of the corrugated photocatalyst of this experimental example and the conventional flat photocatalyst are shown. The flat photocatalyst used for comparison was made by impregnating a 0.5 mm thick alumina-silica ceramic paper with titania sol, drying it and then heat-treating it at about 400°C to 700°C to remove titanium oxide. 300g/J was loaded. As the malodorous gas, 15 ppm of acetaldehyde was used. The measurement results are shown in Table 1.

Table 1 As is clear from the results, by using the corrugated photocatalyst, the decomposition rate can be improved by 30% or more.

Next, a second experimental example will be explained. In this experimental example, in addition to the titanium oxide catalyst used in the first experimental example,
A mixed catalyst of titanium oxide and tungsten oxide was used.

This mixed catalyst is prepared by impregnating an alumina-siliceous ceramic paper with a thickness of 0.5 mm with titania sol, drying it, heat-treating it at about 400°C to 700°C, and then impregnating it with ammonium metatungstate and heat-treating it again. This method supports titanium oxide and tungsten oxide. In this case, the ratio of titanium oxide to tungsten oxide was 85+15 by weight, and the total amount supported was about 600 g/J. In this example, the wave height was 2 mm and the pitch was 3I. The conventional product used for comparison was in the form of a flat plate, similar to the first experimental example. Further, the size of the catalyst used was 63 mm in diameter in all cases. An experiment was conducted under the above conditions and according to the following procedure. First, a mixed catalyst of titanium oxide and tungsten oxide was placed on a stainless steel stand 27 shown in FIG. do. An IOW germicidal lamp is used as the ultraviolet lamp 23, and the ultraviolet intensity at a wavelength of 250 nm is 1. ．． It was 6beW/cJ. Acetaldehyde saturated gas is injected into the reactor 22 from the sampling chamber 24 and stirred with a fan 25 to make the concentration uniform, and the peak area of the gas chromatograph is 10,000.
The average decomposition rate per minute for 30 minutes from the moment when the acetaldehyde concentration showed 0 (corresponding to 70 ppm in acetaldehyde concentration) was defined as the decomposition performance of the catalyst. Next, the hydrogen sulfide decomposition performance of the titanium oxide catalyst was measured. In this case, a 100W germicidal lamp was used as the ultraviolet lamp 23, and the catalyst 26 was placed at a distance of 1001 from the ultraviolet lamp 23. At this time, the intensity of ultraviolet rays at a wavelength of 250 nm was 17 mW/cnf. The initial concentration of hydrogen sulfide was adjusted to be slightly higher than 70 ppm, and the decomposition performance was determined using gas chromatography in the same manner as in the case of acetialdehyde. The decomposition performance of hydrogen sulfide is 30% from the moment the concentration shows 70ppm.
The decomposition rate was expressed as the average decomposition rate per minute.

The results are shown in Table 2.

Table 2 Note: AA Acetaldehyde As shown above, the corrugated plate shape is more efficient in decomposing acetaldehyde by 30% or more, and more than 5 vJ in hydrogen sulfide.

Effects of the Invention As is clear from the above explanation, in the deodorizing method using a photocatalyst of the present invention, by making the photocatalyst into a corrugated plate shape, the area of the photocatalyst can be increased, and at the same time, the efficiency of contact with malodorous gases can be increased. It is an extremely effective invention that allows the decomposition reaction of bad odors to proceed efficiently through photocatalytic action.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of the photocatalyst of the present invention, 12
The figure is a schematic diagram of a flow-type test device for measuring the decomposition performance, and FIG. 3 is a cross-sectional view of the same batch-type test device. 1.2a.2G...photocatalyst, 3.23...ultraviolet lamp.

Claims (1)

[Claims] A deodorizing method using a photocatalyst, in which the catalyst is irradiated with ultraviolet rays in the presence of a corrugated catalyst supporting a semiconductor and a gas containing a bad odor.