JPS604727B2 - Method for removing carbon monoxide from gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing carbon monoxide from a gas containing carbon monoxide.

In recent years, due to the need to prevent indoor and atmospheric pollution, various proposals have been made regarding methods for removing carbon monoxide as part of methods for removing harmful substances from exhaust gas from factories and automobile engines.

In addition, carbon monoxide, which is contained in the gas inhaled into the human body through smoking, has become a focus of attention due to smoking and health issues, and various proposals have been made regarding ways to remove carbon monoxide from the smoke produced during smoking. being done.

Conventionally proposed methods for removing carbon monoxide from gas include: '1' Adsorption method with an adsorbent ■ Absorption method in a solution [3' oxidizing agent or catalytic oxidation to convert carbon monoxide into harmless carbon dioxide Examples include a method of converting it into .

Examples of method '1' include a method using a porphyrin metal coin body as an adsorbent (Japanese Patent Publication No. 54-22951);
There is also a method using a combination of activated carbon and molecular sieve (US Pat. No. 36, No. 06), but the former has the disadvantage of a relatively slow gas adsorption rate, and the latter uses desorption of carbon monoxide once adsorbed. It has the disadvantage that it occurs quickly and cannot be removed sufficiently. An example of the method '2) is the Kollive method (German patent number 1) in which carbon monoxide is absorbed into a toluene solution of cuprous chloride and aluminum chloride complex.
No. 944405, No. 2414801), a method of absorption in a solution consisting of cuprous chloride, a monovalent or divalent metal chloride other than cuprous chloride, and an oxygen-containing organic solvent (Tokukan Sho 54
No. 71788), but it has the disadvantage that it is easily deactivated by the amount of water present, and since it is a liquid absorbent, it is difficult to use. As an example of method [3], hopcalite, which is an oxidation catalyst mainly composed of manganese oxide and copper oxide, has been known for a long time. Although the hopcalite catalyst exhibits high activity even at room temperature or lower temperatures, it is easily deactivated by excess moisture, so it has the disadvantage that the gas to be treated must be completely dried before use. In addition, many metals or metal compounds are known as catalysts that oxidize carbon monoxide to carbon dioxide, but in most cases the temperature range at which catalysts maintain their activity is above room temperature, so carbon monoxide can be oxidized at low temperatures. Various attempts have been made to obtain catalysts that oxidize to carbon (Hakama Kai No. 54-11040, Hakama Kai No. 54-110188, Hakama Kai No. 54-112390, and Japanese Patent Publication No. 54-22791).
These oxidation catalysts are relatively stable against the presence of moisture in the gas, but highly active ones that can be actually used are
Many precious metals such as platinum and palladium are relatively expensive, and the oxidation reaction rate is too slow to oxidize carbon monoxide in a gas flowing at a high flow rate to carbon dioxide, resulting in unsatisfactory effects. There are disadvantages such as not being able to The present invention is a novel method for removing carbon monoxide in gas, which eliminates the various drawbacks of the conventional method for removing carbon monoxide in gas.

That is, the purpose is to provide a novel method for removing carbon monoxide from gas, which has a high carbon monoxide removal rate, does not deactivate in the presence of moisture, maintains its activity at room temperature, and has low removal costs. This is what I did.

The present inventors have conducted various studies on carbon monoxide removal methods that meet this objective, and as a result, have found that a method using reduced nickel is suitable for this objective, and have accomplished the present invention. That is, the present invention is a method for removing carbon monoxide in a gas, which is characterized by bringing reduced nickel into contact with a carbon monoxide-containing gas. The reduced nickel that can be used in the present invention is a powdered or particulate nickel metal that exhibits a reducing action and can be produced by the method exemplified below. That is, 'a method of heating nickel oxide, nickel hydroxide, nickel carbonate, etc. in a hydrogen stream to obtain powdered nickel.' }A method in which an alloy of nickel and an alkali-eluted metal such as aluminum is treated with an alkali such as caustic soda to elute metals such as aluminum and obtain porous so-called Raney nickel, and a nickel monochloride aqueous solution is reacted with zinc powder at the boiling point. A method in which nickel is precipitated and activated by treatment with alkali or acid to obtain so-called Urushibara nickel (Urushibara, Yama B 1. Chem. Soc. Jpn., 25, 280 (19
52)) etc. The reduced nickel obtained as described above adsorbs and contains a large amount of hydrogen gas in its metal structure, or exists in the form of a compound of nickel and hydrogen, and exhibits a reducing action. Therefore, reduced nickel has traditionally been
It has been widely used in applications utilizing such properties, such as as a catalyst for the hydrogenation of oils and fats, a catalyst for the reduction of organic groups such as carbon-carbon multiple bonds, nitro groups, cyano groups, and carbonyl groups. Carbon monoxide is the catalyst poison in this case,
It is known as a substance that degrades catalyst activity. The present inventors focused on this point and discovered that reduced nickel has a high affinity for carbon monoxide and can be used extremely effectively for the purpose mentioned above as a carbon monoxide remover. . Reduced nickel is oxidized in a gas containing oxygen, causing heat generation and deactivation, so when storing it, it must be immersed in alcohol etc. to avoid contact with oxygen.

Therefore, it is necessary to remove oxygen from the gas to be processed in advance. However, 10
Reduced nickel that is stable against oxygen can be obtained by heat treatment to 0 to 300 qo (US Pat. No. 26
No. 41396), if reduced nickel heat-treated in this way is used, it will not be deactivated by oxygen even in an oxygen-containing gas, and carbon monoxide can be effectively removed. There are no particular limitations on the means for bringing the reduced nickel into contact with the gas containing carbon monoxide, and any method may be used as long as it is an effective contacting means. Reduced nickel can be used alone or supported on a suitable carrier such as quartz, pumice, alumina, or silica gel. Removal of carbon monoxide in gas by reduced nickel is achieved rapidly even at room temperature and is almost unaffected even in the presence of moisture.

Although the mechanism by which reduced nickel removes carbon monoxide is not necessarily clear, the fact that methane or formaldehyde, which are usually assumed to be reduction products of carbon monoxide, is not detected at all in the gas after carbon monoxide is removed, suggests that It is thought that this is not due to a simple reduction reaction of carbon monoxide, but is due to a type of adsorption effect. As explained above, reduced nickel has a specific effect on carbon monoxide,
Such an effect can be achieved by using platinum, palladium, which is the oxidation catalyst for carbon monoxide mentioned above, or by using, for example, Tokkan Sho 54-11040.
This effect is completely different from the mechanism of action using oxidation catalysts such as iron, cobalt, and nickel described in the above publication, and is a unique effect found only in reduced nickel. According to the present invention, there are the following advantages and effects compared to conventionally known carbon monoxide removal methods.

That is, since reduced nickel has a high carbon monoxide removal rate '1', it can be applied to gases at high flow rates. ■Highly active even in the presence of moisture. Glue is highly active even at room temperature. ■It is relatively inexpensive. Therefore, the method of the present invention can be used not only to remove carbon monoxide contained in indoor polluted air, various exhaust gases, and other gases, but also to remove carbon monoxide in smoke by applying it to cigarette filters, etc. can. Example 1 30 parts of powder of Ni-mountain alloy (50:50) was added to a solution of 38 parts of caustic soda dissolved on 15 parts of distilled water, and the resulting Raney nickel was activated and washed with water and then with ethyl alcohol. Later, Pyrex pipe (outer diameter 8 side,
It was filled in the center of the inner diameter (6 sides, length 112.5 skins) so that the layer thickness was 5 layers, and both ends were held down with quartz wire.

Connect this Pyrex tube directly to a gas chromatograph,
A mixed gas of 0.3' was passed through at a linear velocity of 35.4 min. The CO removal rate is determined by gasking Pyrex tubes that do not contain reduced nickel.

It was calculated by comparing it with the CO peak area of the gas chromatogram obtained when the mixed gas was directly connected to the matograph and passed through it. Capacity ratio: C03.88%, 0
In the case of a mixed gas of 24.01% and He92.11%, C
100% removal was achieved for both ○ and 02.

Also, C06.03%, C026.21%, CH46.3
When a mixed gas having a composition of 9% He and 81.37% He was passed through, 100% of CO was removed. In addition, these mixed gases are
Even after 10 passes of 0.3 I, the CO removal ability was sufficiently maintained. Example 2 A so-called Urushihara Nickel 200 female obtained by reacting an aqueous solution of nickel chloride containing 10% of nickel equivalent with 10% of zinc powder at the boiling point and treating the precipitated nickel with 13% acetic acid at 160M was made into Pyrex. Pipe (outer diameter 8
It was filled in the center of a 112.5 willow (with an inner diameter of 6 and a length of 112.5 legs), and both ends were pressed with quartz wool.

The CO removal activity was examined using the same method as in Example 1, and the results were as follows. In other words, the capacity ratio is C03.
When a mixed gas of 88%, 024.01%, and 92.11% He was passed through at a linear velocity of 35.4 arc/min at a rate of 10.3, 100% of both C○ and 02 were removed. Also C06.01
%, C026.21%, CH46.39%, He81.
When passing through a mixed gas with a composition of 37%, CO is 100%
Elimination has been achieved. Note that the pressure loss due to the nickel lacquer base was negligible. Example 3 Ni-AI alloy (50:50) grains (10 to 15 mesh) were treated in the same manner as in Example 1, heated at 200° C. under a hydrogen gas stream, and then allowed to cool.

The obtained reduced nickel grains 350 were poured into a Pyrex tube (
Outer diameter 8 side small, inner diameter 6 side? , length 112.5 side) and held both ends with quartz wire. C by the same method as in Example 1
The results of examining the O removal activity were as follows. That is, the capacity ratio is C03.88%, 024.01%, He
Linear velocity of 92.11% mixed gas 35.4cm/min
I got through 10 times with 10.3 each. CO removal rate is 85
%Met. C06.03%, C026.21%, C6.39%, He81.37% in 10.3' increments of 10
In the case of circulation, the CO removal rate was 80%. Example 4 100% reduced nickel similar to that used in Example 1 was added to the filter part of the Japan Monopoly Corporation product name “Highlight”.
9 filled Pyrex tubes were connected with cellophane tape.

Nine puffs per cigarette were smoked using an automatic smoking machine, and the concentration of CO in the mainstream smoke of each puff was measured using a non-dispersive infrared photometer (manufactured by Fuji Electric Keizoku Co., Ltd.). The same Pyrex tube filled with reduced nickel was used until a total of five cigarettes were smoked. As a control, we measured the concentration of CO in mainstream smoke by smoking only highlights, and calculated the CO removal rate in mainstream smoke by reduced nickel based on the calculated value when the removal rate was 0%, and the results are shown in the table below. Shown in 1. As is clear from the results in Table 1, reduced nickel is sufficiently effective in removing CO contained in tobacco bonito. Table 1

Claims (1)

[Claims] 1. A method for removing carbon monoxide in a gas, which comprises bringing reduced nickel into contact with a carbon monoxide-containing gas to bind carbon monoxide to the nickel and removing the carbon monoxide in the gas.