JPS6128452A - Catalyst for removal of carbon monoxide - Google Patents

Abstract

PURPOSE:To enhance the carbon monoxide removal activity of a platinum catalyst and to prolong the life thereof, by preliminarily contacting the platinum catalyst supported by an alumina carrier with gas containing carbon monoxide. CONSTITUTION:The platinum catalyst supported by an alumina carrier is preliminarily contacted with gas containing carbon monoxide at ambient temp. By this method, the carbon monoxide removal activity of the platinum catalyst is enhanced and the usable time thereof is prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a catalyst for removing carbon monoxide used in gas masks used for firefighting and disaster relief at coal mines, or for use in tunnels or garages where there is a possibility of high carbon oxide concentrations. It can also be used for carbon oxide removal. - This invention relates to a carbon monoxide removal catalyst with excellent sustainability of carbon oxide removal ability. Specifically, the present invention relates to a carbon monoxide removal catalyst obtained by contacting a platinum catalyst supported on an alumina carrier with a carbon monoxide removal gas at room temperature.

It was discovered in JP-A No. 5 that platinum catalyst supported on an alumina carrier has a high ability to remove carbon monoxide contained in the air at room temperature.
3-14988J1.

Furthermore, focusing on the high carbon monoxide removal ability of this platinum catalyst, Japanese Patent Application Laid-Open No. 847.44/1983 discloses that it is used as a carbon monoxide removal catalyst in gas masks for fire fighting. Of the above-mentioned publications, the former states that the catalyst with decreased activity should be reactivated at 350 to 800°C, preferably 450 to 550°C, and the latter states that the catalyst can be reactivated after using a gas mask. There is no mention of revitalization.

The main purpose of the present invention is to increase the carbon monoxide removal activity of a platinum catalyst supported on an alumina carrier and to extend the usable life of the catalyst, and also discloses a means for reactivating the catalyst as a result. It is something. The present invention was obtained based on a completely accidental finding, and the inventors themselves could not have predicted it in advance. The present invention will be explained below together with this knowledge.

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 by rules and standards based on the Fire Service Act, for example, and must be extremely strict. - Looking at the removal standards for carbon oxide, in Firefighter Children No. 234, "Standards for Fire Evacuation Protective Equipment, etc." Still 350 pages after 3 minutes
The ability to remove carbon monoxide to below pm is required. 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. -Removal of carbon oxide is carried out by oxidizing CO to 002, They can be distinguished from those that are purified primarily by adsorption or absorption, such as smoke particles and other gases.

The carbon monoxide removal rate of a gas mask can be known by testing only the carbon monoxide removal catalytic ability of the gas mask.

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 oxide 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 tried similar experiments several times, but the results were the same.

The above experimental results show that the carbon monoxide removal ability of a platinum catalyst supported on an alumina carrier is much higher when the catalyst is brought into contact with a carbon monoxide-containing gas at room temperature than when it is a new catalyst. . Also, if this catalyst is used to remove carbon monoxide and reused by leaving it in the air, the activity will improve slightly, but even if you repeat this over and over again, it will not activate the catalyst better. Does not occur. This will become clear in the comparative examples and examples described later. In the present invention, platinum is described as a catalyst metal, but platinum may be supplemented with F e , M n , P as a co-catalyst.
Similar results are shown when b, B i , Ce, etc. are used. Therefore, the platinum catalyst according to the present invention is
It goes without saying that not only platinum but also a metal or metal oxide as a promoter for platinum is included.

The alumina carrier used in the catalyst of the present invention can be any catalyst carrier and will have the same effect, but it is preferably γ-type alumina with a particle size of about 3 to 4 mm. Platinum, which is a catalytic metal, and platinum and a co-catalyst metal may be deposited on a support by a conventional method, and this does not affect the present invention in any way.

Activation of the catalyst is from 500 to 10. This is accomplished by bubbling air containing OOO ppm of CO over the catalyst for 15 minutes or more, and then cutting off the CO during the bubbling, which can be accomplished in a few seconds.

The performance of the platinum catalyst after activation is influenced by the catalyst used for activation, and the performance of the catalyst provided is improved greatly by activation.

In the present invention, the temperature when contacting the new catalyst with a carbon monoxide-containing gas may be room temperature. The term "normal temperature" here does not refer to a specific temperature, but rather refers to the temperature at the processing location at the time of processing, and therefore means that 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, the reason why performance is improved when the platinum catalyst supported on an alumina carrier is brought into contact with a carbon monoxide-containing gas in advance is currently unknown. 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 has been made solely based on findings obtained through experiments.

Example 1 (Comparative example including) Granular activated alumina (3 mmφ, ABD O, 47, surface '1IL 190rrF/g) is immersed in a platinum salt solution according to a conventional method, dried and reduced to give 6 g of platinum per 1α of catalyst. A catalyst like this was prepared. This catalyst is 22wI! A 1 diameter glass tube was filled with 10 cc of the catalyst, and both sides of the filled material were pressed with air-permeable disks to keep the thickness of the catalyst layer within the glass tube constant. Air containing 2500 ppm of carbon monoxide was passed through this glass tube at a space velocity of 1 B and 000 Hr-', and the change in carbon dioxide removal rate over time was measured. The results are shown as line 1 in FIG. In this case, the carbon monoxide removal rate is 8 with 3 minutes of ventilation.
It has fallen to 6%. Line 1 corresponds to a comparative example of the present invention.

Carbon monoxide removal gas was again fed into the glass tube filled with the treated catalyst, and the carbon monoxide removal rate was measured. The results are shown by the line (■) in FIG. # in Figure 1! When comparing I and line ■, the effect of the catalyst of the present invention is clearly visible. In the case of line n, the removal rate of carbon monoxide is over 75% even after 10 minutes, while in the case of line ■ in Figure 1, it is 27%.
It has declined to a certain extent.

Further, the catalyst after the carbon monoxide removal treatment indicated by the line (■) in FIG. 1 was brought into contact with air under the same conditions as the previous time, and then the carbon monoxide removal treatment was performed again under the same conditions as the previous time. The results are shown by the line (■) in FIG.

Line m indicates that even in this case, the carbon monoxide removal rate was slightly improved compared to the previous treatment, but the difference was relatively small.

Although air contact and carbon oxide-containing gas treatment were repeated many times, almost no change was observed in the carbon oxide removal rate.

When activating the catalyst, if the ventilation time of air containing CO is short, the activation will be completed halfway and insufficient activation will be achieved, but by repeating the same activation process again,
It is activated to the same level as the performance shown in (2). The result is line ■ in diagram i.

As shown in (2), when air containing CO is treated in a pulsed manner, that is, when activation is repeated in small steps, for example, air containing 2500 ppm of CO is vented and deaerated at 1 minute intervals (10 seconds). The results obtained when this was repeated are shown in the line ■.

From this result, when this catalyst is used in a mask, it is expected that the catalyst will be regenerated and activated repeatedly, at least in the breathing state, so it is fully expected that the catalyst will have a performance that greatly exceeds the results obtained by the above test method. Example 2 6 g/Q of platinum and 4 g/Q of lead were supported in the form of oxides on the alumina used in the previous example. Using this catalyst, the same treatment as in the previous example was carried out. -The time required for the carbon monoxide removal rate to decrease to 86% for the catalyst that was not treated with the carbon oxide-containing gas was approximately 3 minutes, but the time required for the catalyst that was treated with the carbon oxide-containing gas and then air-treated was approximately 3 minutes. A significant improvement was observed in the duration of activity for removing carbon monoxide, which was 10 minutes.

[Brief explanation of drawings]

Figure 1 shows 1! of carbon monoxide in the catalyst according to this invention. A-&
-YuφIJ+Mackerel hI-Hyo 1-Nii Ni 711 Values 1 ■, ■ and ■, ■ are gases containing a specific concentration of co 15
or 5 minutes with the catalyst, and then c. It is a graph showing the relationship between CO-containing gas flow time (minutes) and CO removal rate when switching to non-containing air for 60 seconds. Note that 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. A carbon monoxide removal catalyst characterized by contacting a platinum catalyst supported on an alumina carrier with a carbon monoxide-containing gas at room temperature.