JP2003311148A - Adsorbent, and method and apparatus for purifying gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adsorbent which can obtain an ultrapure gas by selectively adsorbing and removing minute impurities, such as carbon monoxide, nitrogen, dinitrogen monoxide, nitrogen monoxide, nitrogen dioxide, ammonia, nitrogen trifluoride, carbon dioxide, methane, hydrogen, and oxygen, contained in various gasses to the ppm level or below, and a method and an apparatus for purifying gas using the adsorbent. <P>SOLUTION: A gas to be purified which contains at least one gas among carbon monoxide, nitrogen, dinitrogen monoxide, nitrogen monoxide, nitrogen dioxide, ammonia, nitrogen trifluoride, carbon dioxide, methane, hydrogen, and oxygen, as the trace impurities is brought into contact with the adsorbent made of copper ion-exchanged ZSM-5 zeolite to remove the minute impurities to 1 ppm or less, thereby the purity of the gas to be purified is increased to 99.9999 vol.% or higher. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adsorbent and a gas purification method and apparatus, and more specifically, carbon monoxide, nitrogen, dinitrogen monoxide, and nitric oxide contained in a high-purity gas which is a gas to be purified. And gas purification method and device for obtaining ultra-high purity gas by adsorbing and removing trace impurities such as nitrogen, nitrogen dioxide, ammonia, nitrogen trifluoride, carbon dioxide, methane, hydrogen and oxygen with a selective adsorbent Regarding

[0002]

2. Description of the Related Art Inert gases such as helium, argon, krypton, xenon and nitrogen, and various other gases are widely used in the electronics industry. Such inert gases used in the electronics field include those used in the semiconductor manufacturing process itself and those for general use used as a gas for purging or diluting in every step. The levels of purity achieved vary widely, but at least 99.
More than 999% is required.

Particularly, the gas used in the semiconductor manufacturing process has a strict requirement for purity, and the amount of each impurity is pp.
It is required to be at the b level. The gas to be removed as an impurity in the gas used in the semiconductor manufacturing process is oxygen, carbon dioxide, water, carbon monoxide, hydrogen or hydrocarbons. Further, in the case of rare gases, in addition to the above-mentioned impurities, nitrogen is also a removal target.

On the other hand, in the field of gas adsorption separation, Ca
Zeolites such as -A type, Na-X, and Ca-X type are generally known to adsorb nitrogen and carbon monoxide relatively well, and have been put to practical use. However, the adsorption isotherms of these zeolites are almost linear in the low pressure region, and the adsorption amount for extremely low concentrations of nitrogen and carbon monoxide is small, so it is virtually impossible to purify them at the ppm level. It was

Further, in JP-A-60-156548, ZSM-5 type zeolite having a silica to alumina ratio of 19 or less and containing copper ions is used, and a relatively high concentration of carbon monoxide is contained. A method of recovering carbon monoxide from a gas is disclosed. This method, when separating and recovering carbon monoxide from a gas containing carbon monoxide in a relatively high concentration,
The present invention relates to an adsorbent which has a high adsorption capacity and shows selectivity only to carbon monoxide, and there is no detailed explanation about a trapping method, and basically carbon monoxide existing as a trace impurity in gas is removed. It does not suggest a possibility.

Further, Japanese Patent Laid-Open No. 61-18431 discloses a Y-type, A-type or X-type having a silica to alumina ratio of 10 or less.
A technique for adsorbing and separating carbon monoxide from a mixed gas containing nitrogen and a relatively high concentration of carbon monoxide by an adsorbent in which monovalent copper and / or silver is supported on type zeolite is disclosed. Carbon monoxide in the source gas shown in the examples described in the above publication has a relatively high concentration range,
No mention of removal at the ppm level,
There is no suggestion of using ZSM-5 as the basic adsorbent.

Further, in Japanese Patent Laid-Open No. 3-65242,
As a method for producing a copper-zeolite catalyst, a zeolite having a silica-to-alumina ratio of 5 to 1000 is loaded with copper by ion exchange and dried, and then the zeolite is mixed in a volume ratio of 0.05.
It is disclosed that the heat treatment is carried out in a stream of an inert gas containing 0.5% to 0.5% hydrogen. It is said that ZSM-5 zeolite is most preferable as the zeolite used here, but the one shown as the purification result shows that the purification rate is not higher than the carbon monoxide concentration in the model gas of 0.11% by volume. 5
It is 0 to 75%, which is not the purification at the ppm level, and the removal of nitrogen and the like is not mentioned.

[0008]

As described above, in the conventional adsorption technique, carbon monoxide, nitrogen, dinitrogen monoxide, nitric oxide, nitrogen dioxide, ammonia, nitrogen trifluoride, which are contained in the gas in a trace amount, are used. However, it is difficult to remove impurities such as carbon dioxide, carbon dioxide, methane, hydrogen, and oxygen at the same time, and in particular, there is a problem that the level of removing impurities cannot be set to an extremely small amount of ppm level. Therefore, the present invention selects trace impurities such as carbon monoxide, nitrogen, dinitrogen monoxide, nitric oxide, nitrogen dioxide, ammonia, nitrogen trifluoride, carbon dioxide, methane, hydrogen and oxygen contained in various gases. The object of the present invention is to provide an adsorbent that can be adsorbed and removed to a ppm level or less to obtain an ultrahigh-purity gas, and a gas purification method and apparatus using this adsorbent.

[0009]

In order to achieve the above object, the adsorbent of the present invention comprises carbon monoxide, nitrogen, dinitrogen monoxide, nitric oxide, nitrogen dioxide, ammonia, nitrogen trifluoride, carbon dioxide. , At least one of methane, hydrogen and oxygen
It is an adsorbent for adsorbing and removing the trace impurities from the gas to be purified containing the species as trace impurities, and is characterized by being made of copper ion-exchanged ZSM-5 type zeolite.

First, the gas (purification target gas) to be used for removing trace impurities according to the present invention is, for example, various gases including the inert gas used in the electronics field as described above, and is a typical gas. Examples thereof include various rare gases, hydrogen, oxygen, carbon dioxide, hydrocarbons, hydrocarbons obtained by substituting a part or all of hydrogen with halogen, sulfur hexafluoride and the like. In the present invention, the purity of these gases after purification is 99.9999% by volume or more, that is,
The goal is to reduce the total amount of components contained as impurities after purification to 1 ppm or less.

The adsorbent is a zeolite in which sodium ions of ZSM-5 type zeolite (hereinafter sometimes referred to as ZSM-5) are exchanged with copper ions. In the following description, the copper ion-exchanged zeolite may be referred to as "Cu-ZSM-5".
As the ZSM-5 type zeolite which is a raw material before copper ion exchange, a commercially available material can be used, but a silica to alumina ratio is preferably 5 to 50. ZSM-
If the silica-to-alumina ratio in No. 5 exceeds 50, the amount of copper ion exchange is reduced, and the amount of trace impurities adsorbed is reduced. ZSM- with a silica to alumina ratio of less than 5
No. 5 is difficult to obtain.

The copper ion exchange rate in Cu-ZSM-5 is preferably at least 40% or more of the ion exchangeable amount of each zeolite. this is,
This is because the ion-exchanged copper ions cause specific adsorption of nitrogen and carbon monoxide, and if the copper ion exchange rate is too small, specific adsorption performance will not be exhibited.

The method of ion-exchanging sodium contained in ZSM-5 to copper is not particularly limited,
A well-known method that has been conventionally performed can be adopted. For example, sodium can be ion-exchanged for copper by immersing ZSM-5 in an aqueous solution of a soluble salt of copper (nitrate, acetate, oxalate, hydrochloride, etc.).
In this case, the copper ion exchange amount can be adjusted to a desired amount by selecting the concentration of the copper salt, the immersion time, the immersion temperature, the number of times of immersion, and the like.

After the ion exchange, wash with water,
After being dried, the product is ready for use by firing at an appropriate temperature. At this time, a suitable drying temperature is about 100 ° C., and a suitable baking temperature is 350 ° C. or higher, especially 500 to 800 ° C. in a nitrogen gas atmosphere. Since the specific adsorption performance of this adsorbent is considered to be exhibited by the presence of monovalent copper ions, the change from divalent to monovalent is insufficient at a calcination temperature of less than 500 ° C, and sufficient adsorption performance is exhibited. On the contrary, at a temperature of 800 ° C. or higher, the structure of zeolite itself may be destroyed.

The amount of copper ions contained in the copper ion-exchanged zeolite can be measured by any method.
It can be measured by an ICP emission analysis method (induced charge emission analysis method). The ion exchange rate in the present invention is calculated from the assumption that one copper ion is exchanged with two sodium ions. That is, it is assumed that copper ions are present as divalent at the time of ion exchange. In reality, since monovalent copper ions are also present, an exchange rate of 100% or more may be obtained as a calculated value, and the upper limit is the case where all copper ions are present as monovalent,
The calculated ion exchange rate at that time is 200%.

By using such Cu-ZSM-5 as an adsorbent for trace impurities, for example, rare gas,
Impurities present in trace amounts in gases such as oxygen, hydrogen, carbon dioxide, hydrocarbons, sulfur hexafluoride, such as carbon monoxide, nitrogen, dinitrogen monoxide, nitric oxide, nitrogen dioxide, ammonia, nitrogen trifluoride , Carbon dioxide, methane, hydrogen,
The gas can be purified by efficiently adsorbing and removing oxygen, and the amount of impurities contained in the purified gas can be 1 ppm or less, that is, the purity can be 99.9999% by volume or more.

The gas refining treatment may be carried out by passing the gas to be purified through an adsorption column filled with the adsorbent to bring the gas into contact with the adsorbent. The temperature at which they are brought into contact with each other may be room temperature, for example, in the range of 10 to 40 ° C., and it is almost unnecessary to cool them. Further, the adsorbent having adsorbed the trace impurities can be desorbed to regenerate the adsorbent by heating to a suitable temperature. Therefore, the adsorbent can be repeatedly used by alternately repeating the step of adsorbing a trace amount of impurities performed at a relatively low temperature and the desorption step (regeneration step) performed at a relatively high temperature.

Further, as shown in the schematic system diagram of FIG.
Adsorption cylinder 10 filled with the adsorbent (Cu-ZSM-5)
A plurality of a and 10b are installed, the purification target gas pipes 11 and 12 are connected to the adsorbent regeneration gas pipes 13 and 14, respectively, and the shutoff valves provided in these pipes are opened and closed in a predetermined order. An adsorption step of introducing a gas to be purified into an adsorption column kept at a relatively low temperature, and a desorption performed at a relatively high temperature while circulating the regeneration gas heated by the regeneration gas heater 15 through the adsorption column. By alternately repeating the step and the steps for the plurality of adsorption cylinders a and 10b, it is possible to continuously adsorb and remove the trace impurities in the gas to be purified.

[0019]

Example 1 Sodium-type ZSM-5 zeolite having a silica-to-alumina ratio (Si / Al ratio) of 11.9 (Na-ZSM-5)
Is immersed in a 0.01 molar copper acetate solution at 90 ° C.
Ion exchange was performed for 1 hour. By repeating this operation several times to obtain samples with different ion exchange levels, the ion exchange rates are 0%, 36%, 83%, 12
Five kinds of 1% and 147% were prepared. The amount of copper ion-exchanged with ZSM-5 was measured by ICP emission spectrometry.

As an evaluation of the adsorbent, the adsorption isotherm was measured by the constant volume method. The measurement condition is that the amount of adsorbent used is about 0.
The adsorption temperature was 5 g, the adsorption temperature was 25 ° C., and the vacuum heat treatment at 600 ° C. was performed as a pretreatment of the adsorbent before the adsorption measurement. In Table 1,
Cu-ZSM-5 copper ion exchange rate and adsorption temperature 25
The relationship between the equilibrium adsorption amount of carbon monoxide and nitrogen at an equilibrium pressure of 10 ° C. is shown.

[0021]

[Table 1]

Example 2 Four kinds of ZSM-5 zeolite having different silica to alumina ratios were subjected to the same copper ion exchange operation as in Example 1 to obtain Cu-ZSM-5 having a copper ion exchange rate of approximately 120%. .
As the evaluation of the adsorbent, the adsorption amounts of carbon monoxide and nitrogen were measured in the same manner as in Example 1. In Table 2, Cu
-ZSM-5 silica to alumina ratio and adsorption temperature 25
The relationship between the equilibrium adsorption amount of carbon monoxide and nitrogen at an equilibrium pressure of 10 ° C. is shown.

[0023]

[Table 2]

Example 3 As an adsorbent, Cu-ZSM-5 having a Cu ion exchange rate of 120% and a silica-to-alumina ratio of 19.5 was selected, and the effect of the firing temperature under vacuum on nitrogen adsorption was investigated. In the evaluation of the adsorbent, the amount of adsorbed nitrogen was measured by the same method as in Example 1. Table 3 shows the relationship between the initial firing temperature of Cu-ZSM-5 and the nitrogen equilibrium adsorption amount at an adsorption temperature of 25 ° C and an equilibrium pressure of 10 Pa.

[0025]

[Table 3]

Example 4 The adsorption amounts of carbon monoxide and nitrogen of the adsorbent according to the present invention and the conventional adsorbent (comparative example) were compared. For the adsorbent of the present invention, Cu-ZSM-5 having a silica-to-alumina ratio of 19.5 and a copper ion exchange rate of 120% was selected. As a comparative example, it was found that the adsorption amount of carbon monoxide and nitrogen was large. The Ca-X type to be used was selected. The evaluation of each adsorbent was performed by measuring the adsorbed amounts of carbon monoxide and nitrogen in the same manner as in Example 1. As a pretreatment of the adsorbent before the adsorption measurement, Cu-Z
SM-5 was vacuum-heated at 700 ° C., and Ca-X was vacuum-heated at 350 ° C. for reasons of stability of the agent. FIG. 2 shows adsorption isotherms of carbon monoxide and nitrogen on Cu-ZSM-5 and Ca-X, and Table 4 shows the equilibrium of carbon monoxide and nitrogen at the adsorption temperature of each agent of 25 ° C. and equilibrium pressure of 10 Pa. The relationship of the adsorption amount is shown.

[0027]

[Table 4]

Example 5 As an adsorbent, Cu-ZSM-5 having a silica to alumina ratio of 19.5 and a Cu ion exchange rate of 120% was selected.
The adsorption isotherms of carbon monoxide, nitrogen, dinitrogen monoxide, carbon dioxide, methane, hydrogen, oxygen, krypton, CF ₄ and argon were measured in the same manner as in. Before adsorption measurement, vacuum heat treatment was performed at 700 ° C. as a pretreatment of the adsorbent.
3 and 4 show the adsorption isotherms of each gas on Cu-ZSM-5, and Table 5 shows the relationship between the equilibrium adsorption amount of each gas species at the adsorption temperature of 25 ° C. and the equilibrium pressure of 10 Pa.

[0029]

[Table 5]

As is clear from FIGS. 3 and 4, Cu-
Carbon monoxide, nitrogen, which is to be adsorbed and removed by ZSM-5,
Nitrous oxide and oxygen show chemisorption Langmuir isotherms. On the other hand, rare gases such as argon and krypton, which are to be purified to high purity, and CF ₄ show typical Henry-type adsorption isotherms showing physical adsorption, and these gases have a specific mutual interaction with the adsorbent surface. It turns out that it has no effect. From these, Cu-ZSM-5
On the other hand, it can be seen that the gas having the chemical adsorption property existing in the gas having the physical adsorption property can be easily removed.

Further, from the state of the adsorption isotherm, the strength of the adsorption force of each gas to Cu-ZSM-5, that is, the ease of removal, is as follows: carbon monoxide> oxygen >> dinitrogen monoxide, nitrogen> dioxide. carbon, methane, hydrogen >> krypton, CF _4, is presumed to argon, carbon dioxide exhibiting the same properties, hydrocarbon (methane), hydrogen, by using the Cu-ZSM-5 as the adsorbent, in these gases It is possible to remove carbon monoxide, nitrogen, nitrous oxide and oxygen from the above, and conversely it is also possible to remove these gases by adsorbing these gases from a rare gas using Cu-ZSM-5. Recognize.

Example 6 To burn 100 g of the agent, a diameter of 40 mm and a height of 50
Cu-ZSM-5 was put into a 0 mm stainless steel container, and a method of initial activation of the adsorbent by a firing atmosphere (nitrogen or air) was examined. As the adsorbent according to the present invention, Cu-ZSM-5 having a silica-to-alumina ratio of 19.5 and a Cu ion exchange rate of 120% was selected and heat-treated at 800 ° C. After burning the adsorbent, the adsorption amount of nitrogen was measured by the same method as in Example 1. Table 6 shows the relationship between the firing atmosphere of Cu-ZSM-5 and the nitrogen adsorption amount at the equilibrium pressure of 10 Pa.

[0033]

[Table 6]

Example 7 Cu-Z using a gas containing a trace amount of nitrogen in argon
An SM-5 breakthrough experiment was performed. The suction cylinder has an inner diameter of 20 m.
m-length 500 mm column, silica-alumina ratio 19.5, Cu ion exchange rate 120% Cu-ZS
69.0 g of M-5 was charged. As the measurement gas, a gas containing 512 ppm of nitrogen in argon was used.
The mixture was flown through an adsorption column at 5 ° C., 0.19 MPa and 3.0 L / min, and the nitrogen concentration change at the adsorption column outlet was measured. The nitrogen concentration was measured by discharge emission spectroscopy, and the breakthrough time was the time when the outlet concentration reached 5% of the inlet concentration.
FIG. 5 shows the relationship between the elapsed time and the nitrogen concentration at the outlet of the adsorption column.

Example 8 The agent broke through in Example 7 was regenerated by heating from outside the adsorption column at 350 ° C., and then a breach test was conducted under the same conditions as in Example 7.
Repeated times. As a result of the experiment, the nitrogen breakthrough time of the adsorbent regenerated at 350 ° C. was 88 minutes for the first regeneration and 90 minutes for the second regeneration, which was almost the same time as the result of Example 7.

Example 9 A breakthrough experiment was conducted under the same conditions as in Example 7, except that the experiment temperature was 40 ° C. As a result of the experiment, the breakthrough time of nitrogen was 82 minutes, and it was found that the breakthrough time of this agent was not significantly affected by the experimental temperature.

Example 10 Nitrogen concentration in measurement gas was 99 ppm and flow rate was 0.51 L
/ Min, and the other conditions were the same as in Example 7, and the breakthrough experiment was performed. As a result of the experiment, the breakthrough time of nitrogen was 35.8 hours.

Example 11 Cu-using a gas containing a trace amount of nitrogen in krypton
A breakthrough experiment of ZSM-5 was performed. The suction cylinder has an inner diameter of 20
mm, length 500 mm column, silica-to-alumina ratio 19.5, Cu ion exchange rate 120% Cu-Z
87.4 g of SM-5 was charged. As the measurement gas, a gas containing about 79.8 ppm of nitrogen in krypton was used, and this was used at 25 ° C., 0.35 MPa, 1.1 L / min.
Then, it was flown into the adsorption column and the change in nitrogen concentration at the adsorption column outlet was measured. The nitrogen concentration was measured by discharge emission spectroscopy, and the breakthrough time was the time when the outlet concentration reached 2.5% of the inlet concentration. As a result of the experiment, the breakthrough time of nitrogen was 35.
It's been an hour.

Example 12 Cu-Z using a gas containing a trace amount of nitrogen in argon
An SM-5 breakthrough experiment was performed. The suction cylinder has an inner diameter of 20 m.
m-length 500 mm column, silica-alumina ratio 19.5, Cu ion exchange rate 120% Cu-ZS
87.4 g of M-5 was charged. As the measurement gas, a gas containing 512 ppm of nitrogen in argon was used.
It was made to flow through an adsorption column at 5 ° C, 0.15 MPa and 0.76 L / min, and the change in nitrogen concentration at the adsorption column outlet was measured.
The nitrogen concentration is measured by a gas chromatograph-mass spectrometer (G
C-MS), and the breakthrough time was the time when the outlet concentration exceeded 1 ppm. As a result of the experiment, the breakthrough time of nitrogen was 7.
It's been 9 hours. Further, the outlet nitrogen concentration after 7.8 hours had passed was the detection limit of 5 ppb or less, and it was found that nitrogen was adsorbed and removed to a very low concentration for a long time.

Example 13 A breakthrough experiment of Cu-ZSM-5 was carried out using a gas containing trace amounts of nitrogen and oxygen in krypton. A column with an inner diameter of 20 mm and a length of 500 mm is used as the adsorption column.
Silica to alumina ratio 19.5, Cu ion exchange rate 120
% Cu-ZSM-5 was loaded at 87.4 g. As measurement gas, 1442 ppm nitrogen and 1 oxygen in krypton
A gas containing 1 ppm was used, which was stored at 25 ° C. and 0.15
It was made to flow through the adsorption column at MPa and 0.35 L / min, and the change in nitrogen concentration at the adsorption column outlet was measured. The nitrogen concentration was measured with a gas chromatograph-mass spectrometer (GC-MS), and the breakthrough time was the time when the nitrogen outlet concentration exceeded 1 ppm.

As a result of the experiment, the breakthrough time of nitrogen was 6.2 hours. Further, the concentrations of nitrogen and oxygen at the outlet of the adsorption column after the lapse of 6.0 hours were both below the detection limit of 5 ppb, and it was found that the impurity gas was removed to an extremely low concentration. It was also found that even if two kinds of impurity gases are mixed, both of them can be selectively adsorbed and removed.

Example 14 The agent which was breached in Example 13 was heated and regenerated from the outside of the adsorption column at 350 ° C., and then the breach test was conducted again under the same conditions as in Example 13. As a result of the experiment, the nitrogen breakthrough time of the adsorbent after being regenerated at 350 ° C. was 6.2 hours, which was the same as the result of Example 13.

[0043]

As described above, according to the present invention,
Since trace impurities in gas can be selectively adsorbed and removed, trace impurities to be removed as impurities, for example, carbon monoxide, nitrogen, dinitrogen monoxide, oxygen, etc. It is possible to adsorb and remove the components at the same time, and a high-purity gas containing these impurity components, for example, rare gases such as helium, neon, argon, krypton, and xenon, as well as oxygen, hydrogen, carbon dioxide, and hydrocarbon gases It is possible to obtain a gas in which a part or all of the hydrocarbon gas is replaced with halogen, sulfur hexafluoride, or the like with an extremely high purity.

[Brief description of drawings]

FIG. 1 is a schematic system diagram showing an example of a gas purification apparatus of the present invention.

FIG. 2 shows Cu—ZSM— showing the experimental results in Example 4.
5 is an adsorption isotherm diagram of carbon monoxide and nitrogen on Ca. 5 and Ca-X. FIG.

FIG. 3 shows Cu—ZSM— showing the experimental results in Example 5.
5 is an adsorption isotherm diagram of each gas on FIG.

FIG. 4 shows Cu-ZSM- showing experimental results in Example 5.
5 is an adsorption isotherm diagram of each gas on FIG.

FIG. 5 is a diagram showing a relationship between an elapsed time showing an experimental result in Example 7 and an adsorption cylinder outlet nitrogen concentration.

[Explanation of reference numerals] 10a, 10b ... Adsorption cylinders, 11, 12 ... Pipes for purification target gas, 13, 14 ... Pipings for adsorbent regeneration gas, 15 ... Regeneration gas heater

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[Procedure amendment]

[Submission date] October 15, 2002 (2002.10.
15)

[Procedure Amendment 1]

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[0008]

As described above, in the conventional adsorption technique, carbon monoxide, nitrogen, dinitrogen monoxide, nitric oxide, nitrogen dioxide, ammonia, nitrogen trifluoride, which are contained in the gas in a trace amount, are used. However, it is difficult to remove impurities such as carbon dioxide, methane, hydrogen, and oxygen at the same time, and in particular, there is a problem in that the level of removing impurities cannot be set to an extremely small amount of ppm level . Therefore, the present invention selects trace impurities such as carbon monoxide, nitrogen, dinitrogen monoxide, nitric oxide, nitrogen dioxide, ammonia, nitrogen trifluoride, carbon dioxide, methane, hydrogen and oxygen contained in various gases. The object of the present invention is to provide an adsorbent that can be adsorbed and removed to a ppm level or less to obtain an ultrahigh-purity gas, and a gas purification method and apparatus using this adsorbent.

[Procedure 3]

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The copper ion exchange rate in Cu-ZSM-5 is preferably at least 40% or more of the ion exchangeable amount of each zeolite. this is,
This is because the ion-exchanged copper ions cause specific adsorption of nitrogen, carbon monoxide, etc. If the copper ion exchange rate is too low, specific adsorption performance will not be exhibited.

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Further, as shown in the schematic system diagram of FIG.
Adsorption cylinder 10 filled with the adsorbent (Cu-ZSM-5)
A plurality of a and 10b are installed, the purification target gas pipes 11 and 12 are connected to the adsorbent regeneration gas pipes 13 and 14, respectively, and the shutoff valves provided in these pipes are opened and closed in a predetermined order. An adsorption step of introducing a gas to be purified into an adsorption column kept at a relatively low temperature, and a desorption performed at a relatively high temperature while circulating the regeneration gas heated by the regeneration gas heater 15 through the adsorption column. step and a plurality of adsorption cylinder 10 a, by repeating alternately 10b, and trace impurities refined gas can be continuously adsorbed and removed.

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As is clear from FIGS. 3 and 4, Cu-
Carbon monoxide, nitrogen, which is to be adsorbed and removed by ZSM-5,
Nitrous oxide and oxygen are chemisorbed Langmuir type
The adsorption isotherm is shown. On the other hand, rare gases such as argon and krypton, which are to be purified to high purity, and CF4 show typical Henry-type adsorption isotherms showing physical adsorption, and these gases have a specific interaction with the adsorbent surface. It turns out that you don't have. From these things, Cu-ZS
It can be seen that the gas having the chemical adsorptivity present in the gas having the physical adsorptivity for M-5 can be easily removed.

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Furthermore, the adsorption isotherm or et of each gas Cu-
The strength of adsorption to ZSM-5, that is, the ease of removal is
It is presumed that carbon monoxide>oxygen> nitrous oxide, nitrogen> carbon dioxide, methane, hydrogen >> krypton, CF4, argon, and carbon dioxide, hydrocarbon (methane), and hydrogen showing the same properties are Cu-ZSM. By using -5 as an adsorbent, it is possible to remove carbon monoxide, nitrogen, nitrous oxide and oxygen from these gases, and conversely, using Cu-ZSM-5 from a rare gas. It is understood that these gases can be adsorbed and removed.

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Example 7 Confirmation of adsorption capacity after regeneration of breakthrough Cu-ZSM-5.
Experiments were carried out. First, once to breakthrough the Cu-ZSM-5 using a gas containing trace amounts of nitrogen in argon
It was That is, the suction cylinder has an inner diameter of 20 mm and a length of 50.
Using a 0 mm column, silica to alumina ratio of 19.
5, Cu-ZSM-5 having a Cu ion exchange rate of 120% is 6
Charged 9.0 g. As a measurement gas, a gas containing 512 ppm of nitrogen in argon was used, and this was measured at 25 ° C.
It was passed through an adsorption column at 19 MPa and 3.0 L / min, and the change in nitrogen concentration at the adsorption column outlet was measured. The nitrogen concentration was measured by discharge emission spectroscopy, and the breakthrough time was the time when the outlet concentration reached 5% of the inlet concentration. At this time
FIG. 5 shows the relationship between the elapsed time and the nitrogen concentration at the adsorption cylinder outlet .

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Next, regeneration is carried out using the agent that has been broken through in the above operation.
The experiment was performed twice. That is, the breakthrough agent was heated and regenerated from outside the adsorption column at 350 ° C., and then the breakthrough experiment was repeated twice under the same conditions as in the above operation . Results of the experiment, 3
The nitrogen breakthrough time of the adsorbent regenerated at 50 ° C. was 88 minutes for the first regeneration and 90 minutes for the second regeneration, which was almost the same as the result of the above operation .

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Example8 Breakage was performed under the same conditions as in Example 7 except that the experimental temperature was 40 ° C.
Over-experiment was conducted. As a result of the experiment, the breakthrough time of nitrogen is 82 minutes.
The breakthrough time of this agent has a great influence on the experimental temperature.
I realized that

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Example9 Nitrogen concentration in measurement gas is 99ppm, flow rate is 0.51L
/ Min, and the others under the same conditions as in Example 7
I went. As a result of the experiment, the breakthrough time of nitrogen is 35.8 hours.
Became.

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Example10 Cu-using a gas containing a small amount of nitrogen in krypton
A breakthrough experiment of ZSM-5 was performed. The suction cylinder has an inner diameter of 20
mm column, 500 mm long column
Cu-Z with a mina ratio of 19.5 and a Cu ion exchange rate of 120%
87.4 g of SM-5 was charged. As measurement gas,
Uses gas containing about 79.8 ppm nitrogen in Lipton
At 25 ° C, 0.35 MPa, 1.1 L / min
Flow through the adsorption column with
It was measured. Nitrogen concentration was measured by discharge emission spectroscopy and
Outlet concentration reaches 2.5% of inlet concentration over time
It was time to do. As a result of the experiment, the breakthrough time of nitrogen was 35.
It's been an hour.

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Example11 Cu-Z using a gas containing a trace amount of nitrogen in argon
An SM-5 breakthrough experiment was performed. The suction cylinder has an inner diameter of 20 m.
m, length 500 mm column, silica to aluminum
Cu-ZS with a ratio of 19.5 and a Cu ion exchange rate of 120%
87.4 g of M-5 was charged. Argo as measurement gas
Use a gas containing 512 ppm of nitrogen in the
5 ° C, 0.15MPa, 0.76L / min for adsorption cylinder
Then, the concentration of nitrogen at the outlet of the adsorption column was measured.
The nitrogen concentration is measured by a gas chromatograph-mass spectrometer (G
C-MS) and the breakthrough time is 1 ppm at the outlet concentration.
The time was exceeded. As a result of the experiment, the breakthrough time of nitrogen was 7.
It's been 9 hours. Also, the outlet nitrogen concentration after 7.8 hours has elapsed
The detection limit is 5 ppb or less, which is extremely low for a long time.
It was found that nitrogen was absorbed and removed up to a certain concentration.

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Example 12 Confirmation of adsorption capacity after regeneration of breakthrough Cu-ZSM-5.
Experiments were carried out using gases containing trace amounts of nitrogen and oxygen in krypton . Ie in krypton
Cu-Z using a gas containing trace amounts of nitrogen and oxygen
The SM-5 was once broken umbrella. 20m inside diameter as suction cylinder
m-length 500 mm column, silica-alumina ratio 19.5, Cu ion exchange rate 120% Cu-ZS
87.4 g of M-5 was charged. As a measurement gas, a gas containing 1442 ppm of nitrogen and 11 ppm of oxygen in krypton was used, and this was used at 25 ° C., 0.15 MPa, 0.3
It was made to flow into the adsorption cylinder at 5 L / min, and the nitrogen concentration change at the adsorption cylinder outlet was measured. The nitrogen concentration was measured with a gas chromatograph-mass spectrometer (GC-MS), and the breakthrough time was the time when the nitrogen outlet concentration exceeded 1 ppm.

[Procedure Amendment 14]

[Document name to be amended] Statement

[Correction target item name] 0041

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As a result of this operation , the breakthrough time of nitrogen is 6.2.
It's time. Further, the concentrations of nitrogen and oxygen at the adsorption cylinder outlet after the lapse of 6.0 hours are both 5 pp which is the detection limit.
It was found to be b or less, and it was found that the impurity gas was removed to an extremely low concentration. It was also found that even if two kinds of impurity gases are mixed, both of them can be selectively adsorbed and removed.

[Procedure Amendment 15]

[Document name to be amended] Statement

[Correction target item name] 0042

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Next, using the agent which has been broken through by the above operation,
A regeneration breakthrough experiment was performed once. In other words ,
After heating and regenerating at 350 ° C from the outside of the adsorption column,
The breakthrough experiment was Tsu line under the same conditions as in the case. The result of the experiment, 35
The nitrogen breakthrough time of the adsorbent after regeneration at 0 ° C. was 6.2 hours, which was the same as the above operation result.

[Procedure Amendment 16]

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[Name of item to be corrected] Figure 3

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[Figure 3]

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4D012 BA02 CA20 CB16 CD01 CG01                 4G066 AA61B AA62B BA50 CA27                       CA28 CA29 CA32 CA35 CA37                       CA38 CA51 DA05 FA22 FA34                       FA37 GA06

Claims (8)

[Claims] 1. A purification target gas containing at least one of carbon monoxide, nitrogen, nitrous oxide, nitric oxide, nitrogen dioxide, ammonia, nitrogen trifluoride, carbon dioxide, methane, hydrogen and oxygen as a trace impurity. Is an adsorbent for adsorbing and removing the trace amount of impurities in the copper ion-exchanged Z
An adsorbent characterized by comprising SM-5 type zeolite. 2. The silica-to-alumina ratio of the ZSM-5 type zeolite is 5 to 50.
Adsorbent as described. 3. The adsorbent according to claim 1, wherein the amount of copper ion exchangeable in the ZSM-5 type zeolite is 40% or more. 4. The adsorbent according to claim 1, wherein the calcining temperature of the copper ion-exchanged ZSM-5 type zeolite is 350 ° C. or higher. 5. The purification target gas is a gas containing at least one of rare gas, oxygen, hydrogen, carbon dioxide, hydrocarbon and sulfur hexafluoride as a main component. Adsorbent as described. 6. A purification target gas containing as trace impurities at least one of carbon monoxide, nitrogen, dinitrogen monoxide, nitric oxide, nitrogen dioxide, ammonia, nitrogen trifluoride, carbon dioxide, methane, hydrogen and oxygen. Is copper ion exchanged Z
A gas purification method, which comprises contacting an adsorbent made of SM-5 zeolite to remove the trace impurities from the gas to be purified. 7. The gas purification method according to claim 6, wherein the gas to be purified and the adsorbent are contacted at room temperature. 8. A purification target gas containing at least one of carbon monoxide, nitrogen, dinitrogen monoxide, nitric oxide, nitrogen dioxide, ammonia, nitrogen trifluoride, carbon dioxide, methane, hydrogen and oxygen as a trace impurity. A gas purifying apparatus for adsorbing and removing the trace impurities from ZSM-, which is copper ion-exchanged as an adsorbent for adsorbing and removing the trace impurities.
By installing a plurality of adsorption cylinders filled with type 5 zeolite and repeating alternately an adsorption step performed at a relatively low temperature and a desorption step performed at a relatively high temperature with the plurality of adsorption tubes, A gas refining apparatus which is configured to continuously adsorb and remove trace impurities in a gas to be refined.