JPS5966347A - Ozone decomposing catalyst - Google Patents

Abstract

PURPOSE:To obtain an ozone decomposing efficiency and excellent durability, by compounding Co-oxide, ni-oxide and Mn-oxide in a specific containing ratio. CONSTITUTION:This catalyst comprises three components, that is, Co-oxide (CoOx), NO and MnO2 and, with respect to the contents of the aforementioned components, CoOx is adjusted to 48-80mol%, NiO to 10-38mol% and MnO2 to 2-22mol%. As the result, an ozone decomposing catalyst having both high ozone decomposing efficiency and excellent durability not achieved by a CoRx catalyst or a CoOx-NiO catalyst is obtained. This catalyst can be prepared by a kneading method, a suspension precipitation method or the like. In addition, the shape of the catalyst may be a fine powder, a granule or a pellet having an arbitrary particle size, one obtained by coating the surface of a monolithic ceramic carrier with a catalyst or other shapes.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an ozone decomposition catalyst for use. Ozone, which has strong oxidizing ability, is widely used for purposes such as decolorization, deodorization, sterilization, and COD removal, but during its use, unreacted ozone is emitted into the atmosphere, which may cause secondary pollution. Because there is.

Exhaust ozone must be treated.

This exhaust ozone treatment method has high ozone decomposition efficiency.

It is desirable to have safety, maintainability, compact size, and excellent economic efficiency.

Technologies currently adopted in the field of exhaust ozone treatment include activated carbon method, thermal decomposition method, and chemical cleaning method.Activated carbon method is adopted for low concentration of exhaust ozone, while
For high concentration exhaust ozone of m or more, the thermal decomposition method is often adopted from the viewpoints of safety, maintainability, ozone decomposition efficiency, etc.

However, in order to obtain a high ozone decomposition efficiency of 99°C or higher using the thermal decomposition method, a residence time of 2 seconds at 300°C is required, which is undesirable from the viewpoint of efficiency and compactness. In order to eliminate the drawbacks of this thermal decomposition method, the use of ozone decomposition catalysts has recently been considered, and it is believed that cobalt oxides and the like have excellent ozone decomposition properties as this divine catalyst. It has been reported (! Japanese Patent Application Laid-Open No. 52-75686 and Japanese Patent Application Laid-open No. 53-
14688).

However, after conducting experiments under various conditions using a cobalt oxide (Coax) catalyst as described by the present inventor, the ozone decomposition performance gradually decreased. It was found that it decreased. ,
:do ′ :■、guard゛ 11 Here one piece,、Luto-jimono'' means C'oO, Co, 0
．． .

Collectively refers to co304, etc. When the present inventors analyzed cobalt oxides exhibiting ozonolytic activity by "X1" direct analysis, it was found that in many cases COρ4 was present, in contrast to the main component. However, since it has been confirmed that other substances are also active phases, in the present invention, all of these are referred to as C"0'Ox" in the meaning of Sakura.

In addition, the present inventors have determined that the properties of the C00X catalyst, □Co'Ox, are quasi-Eetschel (N i
) is 1~'3Q%', ;,'%ff5'7+n catalytic power □, compared to conventional catalysts, Co, O, Although the application is pending, even if it is set in a Coax-NiOi medium, 100℃
When used for a long time at low temperatures below.

It was found that there was a slight decrease in performance, and it was desired to develop an ozone decomposition catalyst with higher ozone decomposition efficiency and excellent durability. ．． , ・The purpose of this invention is to improve the Coax catalyst as described above.
云""l: Co□l, 0', x-" Eliminates the drawbacks of the N i O catalyst and provides excellent ozone decomposition activity and durability even at temperatures below 111.09.℃. It is an object of the present invention to provide an ozone content IN! medium.

In order to eliminate the above-mentioned drawbacks of Coax catalysts and Coax-NiO catalysts, the present inventors conducted various experiments and found that NiO If a catalyst '1 with holes added and MnO2 is prepared so as to have the following composition range, it will be a Coax catalyst or C1o Ox-LN.
'i 0 catalyst,! It combines a high oil decomposition rate that cannot be achieved with excellent durability.
Bon, solution 1. :=♂“Get 1i and find 'fc'.
□ ,,, ・■ , ・,・Coax-Ni
O-Mn04-Touch g, o good place Gin group, formation, range is specified using triangular coordinates expressed in moles of each component, the first
It will look like the figure. As shown in this figure, XCo-Co
0X mol%, xN, = mol% of NiO, x
=MnO, the preferable composition n range is within the polygonal region formed by the six straight lines intersecting each other shown below.

More preferably, it is within the area of a polygon B formed by intersecting six straight lines expressed by the following equation.

The preferred composition/range according to the present invention is, as shown in Figure 3 or Figure 4 of the embodiments described below, □ strictly speaking not a polygon, but a polygon like the above □. Square A.

Alternatively, it can be expressed as within the region B.

The catalyst of the present invention can be produced by a method such as a crosstalk method or a suspension precipitation method. Also, what is the shape of the catalyst?

It may be a fine powder, a granule, pellet, or monolithic ceramic carrier having any particle size, coated with a catalyst on the surface thereof, or other shapes.

Therefore, according to the present invention, CoOx, NiO
oh.

The content of MnO,
, an ozone decomposition catalyst prepared in the following manner is provided, and this catalyst can be used for conventional ozone decomposition, CoOx-, as shown in Examples 1-3 below. Superior ozone decomposition compared to NiO catalyst.

・Performance and durability.

On the other hand, the present inventors previously discovered that C was used as a catalyst for ozone decomposition.
A catalyst in which silver (Ag) is supported on an oax-NiO catalyst.

It has excellent ozone decomposition performance at low temperatures, resistance, and labor requirements:'
and all headings, currently patent pending (patent application, 1984-114)
No. 779), but comparing this with the present invention, the present invention has the same effect as supporting expensive Ag, but adding inexpensive MnO□ to the Coax-NiO catalyst. It has the advantage of being obtained by doing so. .

The catalyst of the present invention is a conventional Coax catalyst or a Co0x catalyst.
-The reason why it has superior ozone decomposition performance and durability compared to NiO catalyst is not clear, but within the area of polygon A as mentioned above, mixed oxides with excellent ozone decomposition and decomposition performance I think this is because it is generated.

Examples are provided below to further illustrate the invention.

Dog-4 Down↓ Production performance of Coax-NiO-MnO□ catalyst by kneading method.

Basic carbon M: J /-<)'-to (CoCO,...
Co(OHL) was thermally decomposed at 330°C for 48 hours in an air stream to produce fr-CoOx, nickel hydroxide oxide (NiOOH) (r, NiO obtained by firing at 200°C for 3 hours in an air stream, Carbonated mankan (N1n COs)
t Mn obtained by thermal decomposition at 350°C for 3 hours in an oxygen stream
O2 was mixed so as to have the composition ratio shown in Table 1.

Furthermore, 20% by weight of silica sol was added thereto, thoroughly kneaded, and then heated in air at 200°C for 3 hours. Fill the sized particles into a Pyrex reaction tube (
-6 tests were conducted using the ozone decomposition performance testing apparatus shown in FIG.

In Figure 2, the ozone-containing air discharged from Liga A is humidified in a gas washer G, which simulates the entire water treatment system, and then transferred to an electric furnace filled with an ozone decomposition catalyst I. 1
The ozone concentration in the gas after passing through AfJ flowing into ozone decomposition device M and ozone decomposition device βM is 6111'.
For this reason, three-way cocks C1 and C2 are connected to ozone concentration dllll constant devices 1 and 2, respectively. Noori is a needle valve, F'l and F2 are flow meters, and 11 is a dehumidifier.

Coax-Nio-Mn0 produced by kneading method
2 The ozone decomposition performance of the catalyst was tested using the apparatus shown in FIG. 2. The results are shown in FIG. However, (7 test conditions were as follows.

Catalyst filling Mt: 1.5 cc, catalyst layer temperature: 50°C
, Ozone Kanayama air (exhaust ozone) 〆Flow rate: l, Q t
/n1in, spatial velocity G,f(,S,V,: 40,
000hr', catalyst layer inlet ozone concentration: 2,000
ppm.

FIG. 3 is based on data on the ozone decomposition efficiency of the catalyst shown in Table 1 after 150 hours.

This shows the contour lines of ozone decomposition efficiency with respect to the composition of the catalyst, and the numbers attached to the contour lines are the lateral decomposition efficiency (correspondence).
It was calculated using the following formula.

Month 1 - Peeling Production of Coax-NiO-Mn02 catalyst by suspension precipitation method and its performance.

Cobalt nitrate (C
o (NU3)2: 6H20) and nitric nickel (Ni(NQ)2: 6H20).

By adding ditrilam hydroxide (Na011) water bath solution to this, cobalt hydroxide-nickel hydroxide = M n
An O2 mixture was obtained. However, nitric acid, mankan carbonate, cobal), nickel nitrate V+w, etc. had the same composition as shown in Table 1 of Ri'J, and a mixture was prepared by weighing out a predetermined amount.

After thoroughly washing this mixture with pure water,
It was dried for an hour and then heated at 300° C. for 3 hours in a stream of air. Next, 20% 11% silica sol was added thereto, and the mixture was heated at 200° C. for 13 hours in an air stream to obtain a Coax-NiO-Mr102 catalyst.

The catalyst performance test was conducted in the same manner as in Example 1. Based on the ozone decomposition efficiency of this catalyst after 150 hours, the high line of the ozone decomposition efficiency with respect to the composition of the catalyst is plotted as shown in Figure 4.

Here, in order to compare the performance of the catalyst according to the present invention with that of a conventional catalyst, a conventional Coax catalyst and a Coax-Ni
The performance of the O catalyst is shown in Figure 5. FIG. 5 shows performance test conditions 5. similar to those in Example 1. Figure 1 shows the relationship between the composition of the Coax-N i O catalyst and the oxidation/decomposition efficiency after 150 hours. Shows the performance of the catalyst. As can be seen from FIG. 5, the Coax-NiO catalyst has maximum morn decomposition activity when the NiO content is 15 to 25 moles, but its efficiency is at most 99.3%.

On the other hand, as shown in FIGS. 3 and 4, the Coax-N i 0-MnO2 catalyst of the present invention, namely
ax , the content of NiO and MnO2.

x = 48 mol mol and 80 mol mol Ox, = 10 mol mol and 38 mol 1 It can be seen that under the same reaction conditions as shown in Figure 5, ozone decomposition of 99.4% or more, which is difficult to achieve with conventional Coax catalysts or Coax-NiO catalysts, can be achieved.

Particularly in the CooX-NiO-Mn02 tactile region of the above region, Coax,...:, 6.0 mol+J, Nip:
A catalyst with a composition of 28 monoy, %" + MnO2': 12 mo, ruti has extremely high ozonolysis activity.

Using the apparatus shown in Figure 2, CooX, catalyst, and C
oOx-NiOpNip: 20% mol%) and Co of the present invention, 0x-28 mol%, N
i0. 12 moirete.

The durability of MnO and catalysts was compared. The results are shown in FIG. Test conditions were similar to Example 1.

The characteristic lines C, 2, and H in Fig. 6 are Coax, respectively.
Catalyst, Coax-20 mo = 28 mol% N i O-'', 12 mol% M n 0
It shows the change in ozone decomposition performance with respect to the test time of the two catalysts.

As can be seen from FIG. 6, the catalyst of the present invention is a conventional Coa
x catalyst or Coax-NiO catalyst.

It has extremely excellent ozone decomposition performance and durability.

As described above, the catalyst of the present invention has superior ozone decomposition performance and durability compared to conventional coox catalysts or coax-NiO catalysts, and its adoption makes exhaust ozone treatment equipment more compact and usable. It becomes possible to achieve improvements in economic efficiency due to temperature reduction, etc.

The catalyst of the present invention has been described above as being applicable to the treatment and treatment of high-concentration and high-concentration ozone, but it can also be applied to the treatment of high-concentration ozone generated from various devices such as after copying. can do.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the preferred composition range of the catalyst of the present invention.
．． Figure 2 is a system diagram of the test equipment for testing the ozone decomposition performance and capacity of catalysts, and Figure 3 is the system diagram of the test equipment for testing the ozone decomposition performance and capacity of catalysts.
Figure 4 is a diagram showing the relationship between the composition of the catalyst and the ozone decomposition performance. A diagram showing the relationship between the composition of the catalyst and the ozone decomposition performance. Figure 5 is a diagram showing the relationship between the composition of the conventional CO0X-N,i0 catalyst and the izone decomposition performance. Co0X catalyst, CooX7.20%NiO catalyst and the present invention I) C', oOx -2,,8-e%Ni0
FIG. 2 is a diagram showing the durability of a -12 mol% MnO2 catalyst. A... Oshi, Naiza, c1. c2...Mikata Tsuku,
D...Ozone decomposition catalyst 1M...Ozone decomposition device, K
i. K2Y...Ozone concentration measuring device. f″Il￥1 Sai Z Ward Ya 3 Mouth 1″4 flash

Claims (1)

[Claims] 1) Cobalt oxide (Coax), nickel oxide (N
ip) and manganese oxide (Mn02), and the content of each of the above components is 48 to 80 mole of Coax, 10 to 38 mole of N i O, and 2 mole of MnO.
An ozone decomposition catalyst characterized in that it has a molecular weight of ~22 molar. 2) In the catalyst according to claim 1, the content of each component is 52 to 72 mole of Coax and 16 to 72 mole of NiO.
37 molar ratio and MnO2 is 5 to 20 molar ratio.