JP3213851B2 - Removal method of carbon monoxide in inert gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing carbon monoxide in an inert gas, and more particularly, to a method for removing carbon monoxide from an inert gas such as nitrogen gas, helium, argon or other rare gases as a trace component. how the carbon monoxide removed by adsorption using adsorbents that can <br/> in that the removal of carbon monoxide, to obtain a high-purity gas for about.

[0002]

2. Description of the Related Art When a high-purity gas, for example, an ultra-high-purity nitrogen gas used in the semiconductor industry is obtained by an air liquefaction separation method, it is necessary to separate the nitrogen gas to a very small amount when impurities are separated. , Its process and pretreatment are devised.

[0003] However, carbon monoxide contained in a trace amount in the atmosphere cannot be adsorbed and removed by a normal adsorbent for removing water and carbon dioxide, and its boiling point is close to that of nitrogen. Separation by rectification was also difficult.

Similarly, it has been difficult to adsorb and remove trace amounts of carbon monoxide in other gases under ordinary conditions using a general adsorbent.

[0005] For this reason, various methods have conventionally been used to remove carbon monoxide in the gas.
The conventional method basically treats a gas containing carbon monoxide with a noble metal catalyst or metal oxide, oxidizes carbon monoxide to convert it to carbon dioxide, and adsorbs and removes the generated carbon dioxide with an adsorbent Is what you do.

[0006]

In the conventional method for removing carbon monoxide as described above, first, in the case of an air liquefaction / separation apparatus for producing high-purity nitrogen gas, the produced carbon dioxide is provided to the apparatus. However, since the amount of raw material air introduced as a raw material into the apparatus is large, the tank filled with the noble metal catalyst becomes large, and a large amount of catalyst needs to be used. This leads to an increase in the size and cost of the device.

In the case of treating a gas containing almost no oxygen unlike the raw material air, either a metal oxide is used or a noble metal catalyst is used by adding oxygen to the gas.

When a metal oxide is used, the metal reduced by oxidizing carbon monoxide must be oxidized with a gas containing oxygen and reused, and the generated carbon dioxide fills the adsorbent. It is necessary to provide a separate adsorption tank and remove it. Therefore, when continuously treating the gas to be treated, it is necessary to prepare and use two or more reaction vessels and adsorption vessels each filled with a metal oxide while alternately regenerating them.

In the case of treating with a noble metal catalyst by adding oxygen gas, it is necessary to remove excessively added oxygen in a reaction tank filled with an oxygen-absorbing catalyst such as copper after the reaction. In addition, it is necessary to remove the generated carbon dioxide in an adsorption tank filled with an adsorbent. When continuously treating the gas to be treated, prepare at least two reaction tanks for oxygen removal and two or more adsorption tanks. There is a need to.

That is, in any case, as shown in FIG. 4, at least four processing tanks P and Q are required, and not only the pipe R for the gas to be processed shown in FIG. In addition, a number of valves for switching each processing tank between the processing step and the regeneration step are required. Therefore, not only the device becomes large, but also the configuration is complicated.

[0011] The present invention is a method of removing carbon monoxide in an inert gas using a carbon monoxide removing adsorbent capable of adsorbing and removing carbon monoxide in an inert gas with a simple device configuration It is intended to provide.

[0012]

In order to achieve the above object, the present invention provides a method for removing carbon monoxide in an inert gas.
In a tank, an adsorbent for removing carbon monoxide , in which at least one of palladium and platinum is supported on an adsorbent having a carbon dioxide adsorption ability in a range of 1 to 20% by weight.
And oxygen is added to the palladium and / or platinum.
After binding and activation, oxygen is stored in the tank.
Introduce an inert gas to be treated that is not qualitatively contained,
It is characterized in that contained carbon monoxide is adsorbed and removed .

As a specific means, the above-mentioned paradigm
Activated state in which oxygen is bound to platinum and / or platinum
In the tank filled with the carbon monoxide adsorption adsorbent in the,
An inert gas to be treated substantially free of oxygen is introduced to introduce the inert gas.
Adsorption refining plant that adsorbs and removes carbon monoxide contained in gas
The adsorbent is heated by introducing a regeneration gas containing oxygen.
Heating regeneration step to activate heating regeneration, the regeneration gas or
Cooling step of introducing the purified gas to cool the adsorbent
And introducing the purified gas into the tank to cool the tank
A cooling purge step for purging the regeneration gas in the tank.
Is characterized in that performed sequentially repeated and.

In the present invention, oxygen is substantially contained.
The inert gas to be treated is contained in the gas
All of the carbon monoxide can react to carbon dioxide
Inert gas to be treated which does not contain a certain amount of oxygen .

As the adsorbent used as the adsorbent and metal carrier for adsorbing carbon monoxide, those having the ability to adsorb carbon dioxide as described above, for example, various zeolites can be used. It is preferable to use a 13X zeolite having a high carbon dioxide adsorption ability.

The content of palladium and platinum carried on the adsorbent in the adsorbent is 1 to
The amount is 20% by weight, preferably 2 to 10% by weight. If the amount is too small, carbon monoxide cannot be sufficiently removed, and if it is too large, the removal efficiency cannot be improved.

It should be noted that either palladium or platinum may be used, or both may be used as an appropriate mixture. As a means for supporting palladium and platinum on the adsorbent, a means for supporting such a substance on various carriers can be used.

The above-mentioned adsorbent for adsorbing carbon monoxide is activated by adsorbing or binding oxygen to palladium or platinum previously carried on the adsorbent.
Carbon monoxide contained in the gas to be treated can be chemically adsorbed or converted into carbon dioxide by reacting with oxygen, and the generated carbon dioxide is converted into an adsorbent having a carbon dioxide adsorption capacity as a carrier. Can be adsorbed. Thereby, carbon monoxide is removed from the gas to be treated.

FIG. 1 shows an example of an apparatus configuration for implementing the method of the present invention.

In this apparatus, a pair of adsorption tanks A and B, a main valve 1 and a control valve 2 on the introduction side of the gas to be treated, a purified gas storage tank 3 on the derivation side of the purified gas, and an adsorption tank used for regeneration. An exhaust pipe 4 and a purge gas introduction pipe 8 having a purge valve 5, a control valve 6, and a flow meter 7 for supplying a part of the purified gas during the purge step are provided, and are attached to the respective adsorption tanks A and B. Inlet valves 9a, 9b, outlet valves 10a,
10b, regeneration outlet valves 11a and 11b, and purge gas introduction valves 12a and 12b are provided.

Further, a regeneration gas supply pipe 13 for supplying a regeneration gas for heating and regenerating the adsorbent is provided at an outlet of each of the adsorption tanks A and B, and the regeneration gas is supplied to both the adsorption tanks A and B. A regeneration gas introduction pipe 14 for introduction from an outlet portion is provided, and a heater 15 for heating the regeneration gas to a regeneration temperature is provided in the regeneration gas supply pipe 13. Regeneration gas introduction valves 14a and 14b corresponding to the adsorption tanks A and B are provided.

First, when one adsorption tank A is in the adsorption purification step and the other adsorption tank B is in the regeneration step (heating regeneration, cooling, purging), the gas to be treated, which has been raised to a predetermined pressure, is supplied to the main valve 1 and the control valve. The gas introduced into the adsorption tank A from the inlet valve 9a attached to the adsorption tank A via the valve 2 and treated by the adsorbent in the tank to remove carbon monoxide, and purified gas is supplied to the outlet valve 10a.
After passing through a, it is stored in the purified gas storage tank 3, and a predetermined amount is drawn out from the purified gas supply valve 3a.

In the meantime, a regeneration step is performed in the other adsorption tank B. In this regeneration step, first, after closing the inlet valve 9b and the outlet valve 10b, the regeneration gas introduction valve 14b is opened, the oxygen-containing regeneration gas supplied from the regeneration gas supply pipe 13 and heated to a predetermined temperature by the heater 15 Is introduced from the outlet side of the adsorption tank B.

The amount of oxygen in the heated regeneration gas is 1% by volume or less, preferably 0.1 to 10% by volume, based on the regeneration gas amount.
0.5 vol% is appropriate, and if it is too small, sufficient regeneration cannot be performed, but if it is too large, a sufficient effect cannot be obtained.

The heating temperature of the regeneration gas is 100 to 3
When the temperature is low, sufficient regeneration cannot be performed. When the temperature is high, not only a large amount of heating energy is required, but also the heat resistance of the device is problematic.

Further, as the main component of the regeneration gas, it is preferable to use a gas of the same type as the inert gas to be treated, whereby deterioration of the adsorbent can be suppressed.

The heated regeneration gas containing oxygen is introduced into the tank from the outlet side of the adsorption tank B via the regeneration gas introduction valve 14b, regenerates the adsorbent, passes through the regeneration outlet valve 11b, and is discharged from the exhaust pipe 4. Is done.

As a result, the carbon dioxide adsorbed on the adsorbent is desorbed and discharged, and oxygen is adsorbed or combined with palladium or platinum to perform regeneration and activation.

After performing the heating and regeneration step for a predetermined time, the heating by the heater 15 is stopped, and the adsorbent is cooled by the regeneration gas. In addition, this cooling process may be performed using the following purified gas, but it is preferable to use the regeneration gas used for heating and regeneration.

Next, with the adsorption tank A remaining in the adsorption step, a part of the purified gas is returned to the adsorption tank B from the purge gas introduction pipe 8 through the purge gas introduction pipe 8 via the purge valve 5, the control valve 6 and the flow meter 7 to the adsorption tank B. Then, the inside of the tank is cooled to an adsorption temperature, usually room temperature, and a cooling purge step of discharging the oxygen-containing regeneration gas from the regeneration outlet valve 11b is performed.

Each of the adsorption step, the heating regeneration step, and the cooling purge step is performed for a predetermined period of time, and the adsorption of one adsorption tank A proceeds, and the regeneration step of the other adsorption tank B is completed. And the adsorption tank B enters the adsorption process.
The adsorption tank A enters a heating and regeneration step.

Hereinafter, for example, when purifying nitrogen gas, carbon monoxide in the gas to be treated is continuously removed while sequentially switching the adsorption tanks A and B as shown in FIG.

As described above, according to the method of the present invention using the adsorbent for adsorbing carbon monoxide according to the present invention, the treatment target is treated by substantially the same device configuration and substantially the same operating procedure as those of a commonly used temperature fluctuation adsorption separation device. High purity gas can be obtained by continuously removing carbon monoxide in the gas.

As the regenerating gas, a gas obtained by adding oxygen to the gas to be treated may be used, or a nitrogen gas (oxygen content of 0.1 to 1.0) discharged from the air liquefaction / separation apparatus may be used.
%) Can be used, and by applying the present invention to a nitrogen purification facility of an air liquefaction separator for producing ultra-high purity nitrogen gas, the production cost of ultra-high purity nitrogen gas can be reduced. .

[0035]

Embodiments of the present invention will be described below. Example 1 A column having an inner diameter of 30 mm and a length of 250 mm was packed with 100 g of an adsorbent in which 10% by weight of palladium was supported on synthetic zeolite. As a pretreatment, nitrogen containing 0.1% by volume of oxygen was flowed at 5 liters per minute for 8 hours.
Heated to 200 ° C. Then, after purging with nitrogen gas at 5 liters per minute for 4 hours while maintaining the temperature at 200 ° C., the system was cooled to 25 ° C. while flowing nitrogen gas.

When nitrogen gas containing 10 ppm of carbon monoxide was continuously passed through this column under atmospheric pressure at a rate of 10 liters per minute, as shown in FIG. Carbon was detected after 50 hours.

From this, the processing capacity per unit adsorbent was about 1.5 cc / g as the carbon monoxide processing capacity until carbon dioxide was detected. This value is an extremely large value as the adsorption capacity of carbon monoxide at a low concentration (low partial pressure) as in this example.

Example 2 Two columns packed with the same adsorbent as in Example 1 were prepared.
The adsorption step and the regeneration step were alternately repeated for 24 hours.

In the adsorption step, a nitrogen gas containing 10 ppm of carbon monoxide is treated at 10 liters per minute, and in the regeneration step, nitrogen containing 0.1% by volume of oxygen is flowed at 5 liters per minute. After heating to 200 ° C. for 8 hours and further purging with nitrogen gas at 5 liters per minute for 4 hours while maintaining the temperature at 200 ° C., 25 ° C. while flowing nitrogen gas
Until cooled.

As a result, even if both the adsorption and regeneration steps were repeated, carbon monoxide in the nitrogen gas was completely absorbed and removed, and neither carbon monoxide nor carbon dioxide was detected from the column outlet.

[0041]

As described above, according to the present invention,
Carbon monoxide in an inert gas substantially free of oxygen can be removed only by the adsorption step, and operability, equipment scale,
Significant improvement in equipment cost can be achieved.

Particularly, it is suitable for purifying a gas having a low carbon monoxide content. For example, carbon monoxide in a gas obtained from an air liquefaction / separation apparatus for producing an ultra-high purity gas used in the semiconductor industry can be produced at low cost. , And the production cost of the ultra-high purity gas can be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an example of an apparatus for performing the method of the present invention.

FIG. 2 is a process chart in a case where a pair of adsorption tanks is switched and used.

FIG. 3 is a diagram showing experimental results of Example 1.

FIG. 4 is an explanatory view of a conventional carbon monoxide removing device.

[Explanation of symbols]

A, B ... adsorption tank 3 ... purified gas storage tank 4 ... exhaust pipe 8 ... purge gas introduction pipe 9a, 9b ... inlet valve
10a, 10b ... outlet valve 11a, 11b ... regeneration outlet valve 12a, 12b ... purge gas introduction valve 13 ... regeneration gas supply pipe 14 ... regeneration gas introduction pipe 14a, 14b ... regeneration gas introduction valve 15 ... heater

Claims (2)

(57) [Claims] 1. An adsorbent having a carbon dioxide adsorption ability,
At least one of palladium and platinum
The carbon monoxide removing adsorbent is supported in the range of 20 wt% was filled in the tank, the palladium and / or platinum
After being activated by binding oxygen to the vessel,
An inert gas to be treated substantially free of oxygen is introduced to introduce the inert gas.
A method for removing carbon monoxide in an inert gas, comprising adsorbing and removing carbon monoxide contained in the gas . To wherein said palladium and / or the tank filled with claim 1, wherein the carbon monoxide adsorbing adsorbent in oxygen activation state of being bonded to platinum, substantially free of oxygen
And an adsorption purification step of adsorbing and removing carbon monoxide contained in the gas to be treated and an adsorbent by heating and introducing a regeneration gas containing oxygen. Heating and regeneration step, and a cooling step of introducing the regeneration gas or the purified gas to cool the adsorbent, and introducing a purified gas into the tank to cool the inside of the tank. A method for removing carbon monoxide in an inert gas, comprising repeating the cooling purge step of purging the regeneration gas in order.