JPH03181318A - Catalyst for removal of ozone - Google Patents

Abstract

PURPOSE:To improve ozone decomposing performance and durability by setting a pellet-shaped catalyst of a heavy metal oxide at the upper stream side of a passage and a honeycomb catalyst of the same heavy metal oxide at the downstream side. CONSTITUTION:A catalyst obtd. by pelletizing powder of the oxide of a heavy metal such as Fe, Mn or Cr is set at the upper stream side of a passage. A catalyst obtd. by sticking the same heavy metal oxide to a honeycomb carrier is set at the downstream side. Such characteristics of the pellet-shaped catalyst as about 80-90% initial removal rate and a low coefft. of deterioration are combined with such characteristics of the honeycomb catalyst as about 100% initial removal rate and a high coefft. of deterioration and ozone is removed with high initial efficiency and durability by the synergistic effect of the catalysts.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an ozone removal catalyst for purifying ozone in the air, and particularly to a catalyst for removing relatively high concentration of ozone.

[Prior Art] Ozone is widely used for sterilizing and deodorizing industrial water and water treatment plants, preserving the freshness of food, and is emitted into the air.

Furthermore, in an electronic R copying machine that employs a charging method using corona discharge, corona discharge is carried out in the accumulated air inside the copying machine, so a large amount of ozone is generated inside the copying machine and discharged outside the machine.

The emitted ozone is said to affect the human body, and several ozone removal catalysts have been proposed to adsorb or decompose ozone.

These ozone removal catalysts are roughly divided into pellet type and honeycomb type, and are used depending on their respective applications.The catalyst component is platinum (PT).
, palladium (Pd), manganese (Mn), silver (Ag)
, nickel (Ni), etc. are used.

[Problems to be Solved by the Invention] The ozone removal catalyst described above is used when ozone is at a relatively low concentration of 1100 pp or less. A feature of pellet-based catalysts is that they exhibit catalytic activity over a long period of time.

In other words, initially the ozone removal rate was not 100%, and the ozone removal rate was 8.
Although the removal rate is 0% to 90%, the change in removal rate over time shows that the deterioration coefficient is small and decreases relatively slowly.

On the other hand, honeycomb catalysts exhibit 100% ozone removal in the initial stage, but after a certain period of time, the performance rapidly deteriorates.
Catalytic activity disappears after a short period of time. In honeycomb catalysts, if the amount of catalyst coat a is increased, the activity retention time will increase gradually (proportionally), but there is a limit to the amount of coating, and the activity retention time of pellet catalyst ability will increase. (durability) is difficult to maintain.

The present application compensates for the drawbacks of pellet-based catalysts and honeycomb-based catalysts, and provides a catalyst for removing relatively high concentrations of ozone.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and the ozone removal catalyst of the present invention includes a catalyst formed by processing heavy metal oxide powder into pellets on the upstream side, It is characterized in that a catalyst in which heavy metal oxides are attached to a honeycomb carrier is provided on the downstream side. Here, if the honeycomb catalyst is placed on the upstream side, a constant I
H11: After the lapse of time, the performance suddenly deteriorates and the catalyst activity disappears in a short period of time, so the pellet catalyst must be placed on the upstream side. Furthermore, both catalysts are usually spaced apart.

The heavy metal oxide is preferably an oxide of iron (Fe), manganese (M n ), chromium (Cr), or copper (Cu), and particularly preferably an oxide of manganese and copper.

[Function] In the present invention, a pellet-based catalyst with good durability performance,
By combining honeycomb catalysts with good initial performance, a synergistic effect occurs and a catalyst with good initial and durable performance can be obtained.

[Example] 1 kg of commercially available electrolytic M n O2 powder and Cu SO
4 Add KOH aqueous solution to the aqueous solution to adjust the pH to 8.
H) Obtain a precipitate of 2, and after filtration, wash with several amounts of water to wash away the potassium component (K) and sulfate group component (304'-).
Cu(OH) obtained by drying at 100°C for 24 hours
2 powder and 300g of MnO2/Cu (OH)
A mixture A of 2 was obtained.

Next, 5 in 2 sol (Snowtex O manufactured by Nissan Chemical Co., Ltd.) was added to mixture A at a ratio of 10 g per 100 g of mixture A, and after kneading with a kneader, it was molded into a size of 3° x 5 L, ass) with an extrusion molding machine. After drying at 100° C., catalyst B was obtained.

Also, add 100 g of water and 20 g of SiO2 sol to mixture A.
and milled with a ball mill for 24 hours to obtain MnO2/
A slurry of Cu(OH)2 was obtained.

This slurry was coated on a ceramic honeycomb carrier of 200 cells/in 2 in an amount of 200 g per 1 g of carrier, and dried to obtain catalyst C.

Catalyst 850cc and 50"X25L (about 50cc
) was placed in a 50" glass reaction tube, catalyst C was installed on the downstream side, catalyst B was installed on the upstream side, and ozone 2,
000 ppm/air at a catalyst hole gas temperature of 25°C, 16.
It was flowed at 6N/min. [Space velocity (SV) + 10,00
0Hr-'] Measure the change in ozone removal rate over time B, +f,
This is represented by curve 1 in FIG.

Comparative Example 1 100 cc of Catalyst B in Example was taken and set in a 5011 reaction tube, and the same test as in Example was conducted, and the results are represented by curve 2 in FIG.

Comparative Example 2 Catalyst C was prepared in the same manner as Catalyst C in Example except that a 5011 x 50 L (about 100 cc) honeycomb carrier was used.
I got -. This catalyst was subjected to the same test as in the example,
The results are represented by curve 3 in FIG.

As is clear from curve 1 in FIG.
Ozone removal and decomposition performance does not deteriorate even after 00 hours have passed.

On the other hand, curve 2 (Comparative Example 1) showing the characteristics of the pellet catalyst shows almost no change in durability performance, but the initial performance shows only 80 to 90% ozone removal rate.

Curve 3 showing the characteristics of the honeycomb catalyst shows 100% of the initial performance, but after about 50 hours the performance drops rapidly and after 100 hours it shows almost no effect.

[Effects of the Invention] As is clear from the above, the ozone removal catalyst of the present invention has improved both ozone decomposition performance and durability due to the synergistic effect of combining a pellet catalyst and a honeycomb catalyst. .

Claims (1)

[Claims] An ozone removal catalyst characterized in that a catalyst made of heavy metal oxide powder processed into pellets is provided on the upstream side, and a catalyst made of heavy metal oxides adhered to a honeycomb carrier is provided on the downstream side.