JPH03188940A - Catalyst for decomposition of ozone - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the ozone decomposing ability of a catalyst under severe conditions by using the oxides of one or more kinds of metals selected among V, Mo, Zr, Sn, Nb and W and Ti oxide as the principal components of the catalyst. CONSTITUTION:A catalyst for decomposition of ozone contg. the oxides of one or more kinds of metals selected among V, Mo, Zr, Sn, Nb and W and Ti oxide as the principal components is produced by impregnation, kneading, coprecipitation, precipitation, mixing or other means. The catalyst may be a binary catalyst such as V2O5-TiO2 or MoO3-TiO2 or a ternary catalyst such as MnO2-V2O5-TiO2 or MnO2MoO3-TiO2. The pref. amt. of the oxides of one or more kinds of metals selected among V, Mo, Zr, Sn, Nb and W is about 5-75wt.% (expressed in terms of the metals) and that of the Ti oxide is about 25-95wt.% (expressed in terms of Ti).

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a catalyst for decomposing and removing ozone contained in a gas or the like.

<Prior art> Conventionally, as methods for removing ozone, a harmful component contained in gases, adsorption methods using porous materials such as activated carbon and zeolite, and oxidative decomposition methods using catalysts such as MnO2 have been proposed. There is.

<Problems to be Solved by the Invention> 1- However, none of the above conventional ozone removal methods can be said to be fully satisfactory.

In other words, the adsorption method has the problem that the period during which the adsorbent exerts its adsorption capacity is limited, so it requires regeneration, etc., and maintenance of the removal equipment requires a great deal of labor and expense. .

Further, although the oxidative decomposition method does not have the above-mentioned problems, there is a problem in that conventional ozone decomposition catalysts cannot sufficiently oxidize and decompose ozone.

The present invention was devised to solve these problems that conventional ozone removal methods had, and first of all, the present invention aims to improve the ozone removal ability compared to the conventional methods. An object of the present invention is to provide an ozone decomposition catalyst that makes it possible to establish an excellent ozone removal method.

By the way, durability tests were conducted on various ozone decomposition catalysts, and it was found that the performance of some catalysts deteriorates significantly when used under harsh conditions with high ozone concentrations and large area velocities. 2- It happened.

The present invention has been made based on this knowledge, and a second object thereof is to provide an ozone decomposition catalyst that does not deteriorate even when used under such severe conditions.

Means for Solving the Problem> The ozone decomposition catalyst according to the present invention for achieving the above object contains vanadium (V), molybdenum (Mo), zirconia (Zr), tin (Sn), and niobium (Nb). and tungsten (W), and an oxide of titanium (Tf) as main components.

Catalysts whose main components are an oxide of at least one metal selected from V, Mo5Zr, Sn, Nb, and W, Ti, and a metal oxide include V2O5-Ti20,
MnO3-TiO2, Zr02Ti02.5n02T
Examples include those whose main component is a binary catalyst such as iO2, Nb205-TiO2, or WO3-TiO2. or. It can be manufactured by appropriately selecting known manufacturing methods such as the dual catalyst mixing method. In the production of the catalyst, a shaping aid may be added to give the catalyst shapeability, and reinforcing agents such as inorganic fibers and organic binders may be added as appropriate to improve mechanical strength etc. .

The reaction temperature during ozonolysis is preferably 0 to 40°C,
10-30 degreeC is more preferable. This is because if the temperature is less than 0°C, the reaction rate will be slow, and if it exceeds 40°C, additional thermal energy will be required to raise the temperature, which is uneconomical.

Further, the contact between the catalyst and the reaction gas is preferably performed at an area velocity (AV) of 5 to 700. This is because if the areal velocity is less than 5, a large amount of catalyst is required, and if the areal velocity is more than 70, the efficiency is low and a predetermined decomposition rate cannot be obtained. Here, the areal velocity is a value obtained by subtracting the space velocity (1/Hr) by the gas contact area (body/arm) per unit volume.

By the way, in ozone decomposition, the inlet ozone concentration (pp
m) and the areal velocity (hereinafter referred to as rcAJ and 5-. MnO2 may be further added to the medium to form the following three-way catalyst. Examples of such a three-way catalyst include Mn02-V2O5
-TiO2, MnO, -MoO3T]02,Mn
O, -Zr02-TiO2, MnO2-3nO2-Ti
O2, MnO2-Nb, 06-TiO2, Mn02-
Examples include WO3-Ti02.

Suitable content (wt%) of at least one metal oxide selected from VSMo, Zr5Sn, Nb and W
, hereinafter the same) is 5 to 75 in terms of the content of elemental metal.
%, and the preferred content of the TI gold metal oxide is 25 to 95% in terms of the content of elemental metal.

The shape of the catalyst according to the present invention is not particularly limited, and various shapes such as a honeycomb shape, a pellet shape, a columnar shape, a plate shape, a pipe shape, etc. can be used.

The active component content in the catalyst is preferably 60% or more, and 7
More preferably 5% or more.

Catalysts can be used by impregnation, kneading, co-precipitation, precipitation, etc. If ozone decomposition is carried out under mild reaction conditions with a small amount of acid (acid), deterioration of the catalyst will usually hardly occur;
Under severe conditions of 0 or more, many catalysts experience severe performance deterioration.

The catalyst according to the present invention as described above shows no deterioration in performance even under severe conditions where CA is 30 or more.

<Examples> Hereinafter, the present invention will be described in detail based on Examples. However, the present invention is not limited to the following examples.

k Catalyst Q training Example 1 Specific surface area 85/g anatase type Ti02200g,
Vanadyl oxalate aqueous solution (150g/fl asV206)
140m! Then, an appropriate amount of water was added and thoroughly kneaded, kneaded on a water bath, and then dried, and the dried product was calcined at 350° C. for 2 hours. The baked product thus obtained was pulverized, water and glass peas were added, and the mixture was stirred and mixed for 30 minutes to form a slurry. This slurry has a porosity of 81% and a pitch of 4゜0mm.
V, 05-Tie2 (weight ratio 10:90)
A two-way catalyst was obtained in which the following was supported at a loading rate of 95%.

Example 2 In Example 1, instead of the vanadyl oxalate aqueous solution, ammonium mobdate aqueous solution (67 g/uasMoOa) 3
In the same manner as in Example 1 except for adding 28iU, Mn05-Tie2 (weight ratio 10:90) was added at a loading rate of 1.
A binary catalyst supported at 0.01% was obtained.

Example 3 MnO,
A two-way catalyst was obtained in which -Tie2 (weight ratio 10:90) was supported at a loading rate of 100%.

Example 4 7- A mixture of 30 g of MnO2 with specific surface area IL8T11'/g, titanium tetrachloride and silica sol (Ti02:5i0
While stirring and mixing 70 g of 1:2 and 1), ammonia gas was blown in to perform a neutralization reaction, thereby producing a slurry-like precipitate. After washing the obtained precipitate thoroughly with water,
Sintered at a temperature of 500°C for 3 hours and pulverized to a specific surface area of 162wl.
1/g MnO2-TiO2-9i02 powder was obtained. Thereafter, in the same manner as in Example 1, Sin2-MnO2-
99% support rate of Ti02 (weight ratio 35:30:30)
A supported three-way catalyst was obtained.

- Catalyst activity test Regarding each catalyst obtained in Examples 1 to 6 and Reference Example above,
A catalyst activity test was conducted under the following reaction conditions using a test apparatus whose flow sheet is shown in FIG. In the figure, (1) is an ozone generator, which generates the ozone,
This ozone-containing air is guided to the catalyst layer (2). The ozone decomposition rate (%) is determined by the following formula from the ozone concentration values at the inlet and outlet of the catalyst N (2) measured by the ozone analyzer (3). 5n
S04 aqueous solution (100g/Q, as SnO2) 22
In exactly the same manner as in Example 1 except for adding 0 ml,
5nO2-Tie, (weight ratio 10:90) at a loading rate of 9
A binary catalyst supported at 6% was obtained.

Example 5 In Example 1, an aqueous solution of niobium hydroxide in oxalic acid (30 g/asN b 205
) A two-way catalyst in which Nb2O6TlO2 (weight ratio 10:90) was supported at a loading rate of 98% was obtained in exactly the same manner as in Example 1 except that 733 mR was added.

Example 6 In Example 1, ammonium metatungstate aqueous solution (50% asWOa) was used instead of vanadyl oxalate aqueous solution.
) WO3-Tie2 (weight ratio 10:90) was added at a loading rate of 10 in the same manner as in Example 1 except that 44 g of
A binary catalyst supported at 2% was obtained.

Reference example 8- Calculated using

Ozone decomposition rate (%) = (Reaction conditions ■) Area rate: 25 tn'/ll・Hr Input ozone concentration: 0.2 ppm Reaction temperature: 20°C (Reaction conditions ■) At a reaction temperature of 20°C, CA was 10.30. The inlet ozone concentration and area velocity were variously changed so as to be 50 or 70, and the ozone decomposition rates were measured at the initial stage, after 1 hour, and after 2 hours, and the deterioration of each catalyst was investigated.

The above test results are shown in Tables 1 and 2.

10- Reaction conditions I Reaction conditions ■ 13- Table 2 Reaction conditions ■ Wood (ppm ・rt?/i ・Hr) As is clear from the above table, all the catalysts obtained in Examples 1 to 6 were It has a higher ozone decomposition rate (%) and durability under severe conditions than the obtained catalyst.

The above test results show that the catalyst produced by the method of the present invention has high ozone decomposition performance and durability under severe conditions.

<Effects of the Invention> The ozone decomposition catalyst according to the present invention has an excellent effect of efficiently removing ozone.

[Brief explanation of drawings]

FIG. 1 is a flow sheet of the catalyst activity test. (1) Ozone generator (2) Catalyst layer (3) Ozone analyzer 14-

Claims (1)

[Claims] An oxide of at least one metal selected from vanadium (V), molybdenum (Mo), zirconia (Zr), tin (Sn), niobium (Nb), and tungsten (W), and titanium (Ti). An ozone decomposition catalyst characterized by containing an oxide as a main component.