JPH0478342B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for activating a carbon monoxide removal catalyst, which is activated by contacting a platinum catalyst supported on an alumina carrier with a carbon monoxide-containing gas, and further relates to the present treatment method. The catalyst obtained can be used as a carbon monoxide removal catalyst for gas masks used for firefighting and coal mine disaster relief, or for carbon monoxide removal in tunnels or garages where there is a possibility of high carbon monoxide concentrations. The present invention relates to an excellent carbon monoxide removal catalyst that has high carbon monoxide removal activity and a long catalyst life, which can also be used.

It is disclosed in JP-A-53-149888 that a platinum catalyst supported on an alumina carrier has a high ability to remove carbon monoxide contained in the air at room temperature. JP-A-57-84744 also discloses the use of this as a carbon monoxide removal catalyst in fire-fighting gas masks. Of the above public announcements,
In the former case, the reactivation of the catalyst whose activity has decreased is
It is clarified that the temperature should be 350 to 800°C, preferably 450 to 550°C, and the latter does not mention reactivation of the catalytic ability after using a gas mask.

The main purpose of the present invention is to improve the carbon monoxide removal performance of a platinum catalyst supported on an alumina carrier and to extend the usable time of the catalyst, and also discloses a method for activating the catalyst.

At the site of a fire or a coal mine fire, a large amount of toxic gases and soot are generated. Therefore, firefighters and rescue workers who enter such sites must carry gas masks, and gas masks for workers must also be prepared inside coal mines. The performance required of this gas mask is regulated, for example, by rules and standards based on the Fire Service Act, and it is regulated that high carbon monoxide removal activation must be maintained for a predetermined period of time. That is,
Looking at the removal standards for carbon monoxide, Fire Service Prefecture No. 234, ``Standards for fire escape protective equipment, etc.'' specifies that air with a carbon monoxide concentration of 2500 ± 250 ppm is passed through a test mask at a ventilation rate of 30/min. The company requires the ability to remove carbon monoxide to less than 350 ppm even after passing through the water for 3 minutes. This legal regulation not only regulates the removal of carbon monoxide, but also the degree of reduction in smoke concentration and the increase in ventilation resistance, but carbon monoxide is removed by oxidizing carbon monoxide to carbon dioxide. The carbon monoxide removal rate of gas masks is based only on the carbon monoxide removal catalytic ability of gas masks. It can be known by measuring.

Now, while testing the carbon monoxide removal ability of a catalyst supported on an alumina carrier, the present inventors happened to measure the carbon monoxide removal ability of a used waste catalyst whose carbon monoxide removal ability had decreased. Contrary to predictions that the performance would remain low or show lower values, it showed extremely high carbon monoxide removal performance. This was a completely unexpected phenomenon, so I conducted similar tests several times, but the results were the same each time.

The above test results show that the carbon monoxide removal ability of the platinum catalyst supported on an alumina carrier is much higher when the platinum catalyst is brought into contact with a carbon monoxide-containing gas than when it is a fresh catalyst.

The present invention was obtained based on such a completely accidental finding, which the inventors themselves could not have predicted in advance.

Any alumina carrier used in the catalyst of the present invention can produce the same effect as long as it is a catalyst carrier, but preferably the particle size of γ-type alumina is 3 to 4 mm.
It is desirable that the degree of Platinum, which is a catalytic metal, may be deposited on the carrier by a conventional method and does not affect the present invention in any way.

In the activation treatment method of the present invention, carbon monoxide gas is supplied to the air to prepare a carbon monoxide-containing gas having a carbon monoxide concentration of 500 to 10,000 ppm, and the carbon monoxide-containing gas is used to coat platinum on an alumina carrier. After the carbon monoxide removal catalyst on which the catalyst is supported is subjected to an aeration reaction treatment for 15 minutes or more, the supply of carbon monoxide gas to the air is interrupted, or the aeration of the carbon monoxide-containing gas is interrupted and the catalyst is removed. By cutting off contact with carbon oxide, the carbon monoxide removal ability of the carbon monoxide removal catalyst can be significantly improved and activated. In other words, by discontinuing contact with carbon monoxide, not only the carbon monoxide removal activity can be restored to its original level, but also the contact life can be extended, allowing high activity to be maintained for a longer period of time. .

The performance of the platinum catalyst after activation treatment depends on the catalyst used for activation treatment, and the better the performance of the catalyst used, the greater the improvement in performance due to activation.

In the present invention, the temperature when contacting the catalyst with a carbon monoxide-containing gas may be room temperature. And the normal temperature here does not refer to a specific temperature,
This means that the temperature at the treatment location at the time of treatment is sufficient, and therefore the temperature may vary between summer and winter. However, in order to keep the quality of the catalyst constant, it is desirable to set the room temperature at 20°C or 25°C, and to adjust the temperature of the carbon monoxide-containing gas (the same applies to the catalyst to be treated), the gas is added to that temperature. It does not prevent heating or cooling.

In the present invention, it is currently unclear why the performance is improved when the platinum catalyst supported on an alumina carrier is catalyzed with a carbon monoxide-containing gas and the catalyst is interrupted. Although some speculation has been made as to the reason, it is not conclusive, and therefore, it is reasonable to assume that the present invention was made solely based on findings obtained through experiments.

However, it is a completely unexpected effect that the carbon monoxide removal activity is not only restored but also that the decay rate of the activity can be reduced and the catalyst life can be improved.

The present invention will be explained in more detail below with reference to Examples.

Example 1 100 ml of a nitric acidic aqueous solution of dinitrodiaminoplatinum containing 0.6 g of platinum was immersed in 100 ml of granular activated alumina support (ABD0.47, 3 mmφ) for 2 hours, drained, and dried at 120°C for 2 hours. Catalyst 1 was reduced in a hydrogen stream at 300°C for 1 hour.
Catalyst A was prepared in which 6 g of platinum was supported per catalyst. Next, carbon monoxide gas was supplied to the air to prepare a carbon monoxide-containing gas having a carbon monoxide concentration of 2500 ppm, and the carbon monoxide-containing gas was passed through 10 ml of this catalyst A at a space velocity of 18000 Hr ^-1 for 15 minutes to activate it. A chemically treated catalyst B was prepared.

[Measurement test of carbon monoxide removal ability]

A glass tube with an inner diameter of 2 mm was filled with 10 ml of the sample, and both sides of the sample were pressed with air-permeable disks to maintain a constant thickness of the sample inside the glass tube. Air containing 2500 ppm carbon monoxide was passed through this glass tube at a space velocity of 18000 Hr ^-1 , and the change in carbon monoxide removal rate over time was measured.

The results are shown in Figure 1. For new catalyst A, line I;
Catalyst B is shown by a line, and Catalyst B after the measurement test, that is, Catalyst C, which was subjected to the same activation process as that of Catalyst A, is shown by a line.

Regarding the new catalyst A which has not been activated with a carbon monoxide-containing gas, its carbon monoxide removal rate has already reached 86 after 3 minutes of aeration of the carbon monoxide-containing gas.
%, and after 10 minutes it drops to about 27%. The line corresponds to a comparative example of the present invention.

However, catalyst B of the present invention, which was prepared by activating with a carbon monoxide-containing gas and then interrupting aeration of the carbon monoxide-containing gas, was subjected to a measurement test for carbon monoxide removal ability similar to the activation treatment. As is clear from the line in Figure 1 showing the results, the carbon monoxide removal activity recovered to its initial state as the aeration of the carbon monoxide-containing gas was interrupted, and even more surprisingly, even after 10 minutes had elapsed. The carbon monoxide removal rate still remains at over 75%. Comparing the lines in Fig. 1, it can be seen that the carbon monoxide removal catalyst of the present invention, which has been subjected to the activation treatment method of the present invention in which contact treatment is carried out in advance with a carbon monoxide-containing gas, has a long catalyst life with less attenuation of catalyst activity. It is obvious at a glance that it has

From the line in FIG. 1, the monoxide of catalyst C was measured after 15 minutes of a test to measure the carbon monoxide removal ability, which was substantially equivalent to the activation treatment of the present invention, on catalyst B which had been subjected to the activation treatment of the present invention. Looking at the change in carbon removal rate over time, the carbon monoxide removal rate was slightly improved compared to catalyst A and catalyst B of the present invention, although the difference was relatively small. Catalyst life is also improved. This clearly shows that even if the catalyst of the present invention is repeatedly used for carbon monoxide removal, its carbon monoxide removal ability does not easily deteriorate.

In the catalyst activation treatment method, if the passage time of air containing carbon monoxide is short, activation will be completed halfway and insufficient activation will be achieved, but by repeating the same activation treatment again, The performance is activated to the same level as that shown in the figure below. This result is shown by the line in the figure. In addition, when air containing carbon monoxide is treated in a pulsed manner, that is, when the activation process is repeated in small steps, for example, air containing 2500 ppm of carbon monoxide is vented and deaerated (for 10 seconds) at 1 minute intervals. The line shows the results when the process was repeated.

From this result, when the present catalyst is used in a gas mask, for example, it will be regenerated and activated repeatedly under breathing conditions, so the performance will far exceed the results obtained by the activation treatment according to the present invention. We can fully expect that.

[Brief explanation of drawings]

FIG. 1 is a graph showing the carbon monoxide removal rate of the catalyst according to the present invention together with comparative examples.
, and are the results when a gas containing a specific concentration of carbon monoxide is brought into contact with the catalyst for 15 or 5 minutes, and then brought into contact with carbon monoxide-free air for 60 seconds.
It is a graph showing the relationship between carbon monoxide-containing gas flow time (minutes) and carbon monoxide removal rate. The line in the figure shows the relationship when ventilation and de-insufflation (10 seconds) are repeated at 1-minute intervals.

Claims (1)

[Claims] 1. Carbon monoxide removal characterized by contacting a carbon monoxide removal catalyst in which a platinum catalyst is supported on an alumina carrier with a carbon monoxide-containing gas, and then cutting off the supply of the carbon monoxide-containing gas. Catalyst activation treatment method. 2. The method for activating a carbon monoxide removal catalyst according to claim 1, wherein the contact treatment between a carbon monoxide-containing gas and the carbon monoxide removal catalyst is carried out at room temperature.