JP2005319345A - Inert gas refining agent and inert gas refining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an inert gas refining agent having the high removing capacity of carbon dioxide contained as impurities and capable of removing a very small amount of carbon dioxide up to an extremely low concentration without heating an inert gas at the time of refining and supplying the inert gas of high purity continuously and easily without lowering the removing capacity of carbon dioxide even if the refining agent is repeatedly regenerated, and an inert gas refining method. <P>SOLUTION: In refining the inert gas using the refining agent, the inert gas is brought into contact with the refining agent prepared by making a carrier based on nickel to remove carbon dioxide contained in the inert gas carry a carbonate and/or bicarbonate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inert gas purification agent and a purification method. More specifically, the present invention relates to an inert gas purification agent and a purification method that have a high ability to remove carbon dioxide, oxygen, and the like contained as impurities in an inert gas and that can remove these impurities to an extremely low concentration.

  In semiconductor manufacturing processes, inert gases such as helium, nitrogen, and argon are frequently used. Inert gases such as nitrogen are industrially produced by a method of fractionating liquid air, but these inert gases contain carbon dioxide, oxygen, etc. in the order of several ppm to several hundred ppm. Yes. In the semiconductor field, these inert gases are strongly required to have extremely high purity as the film forming technology advances, and since they are used in large quantities, they are continuously used in semiconductor manufacturing processes with high purity. There is a need for an inert gas purification agent and method that can be supplied.

  For this reason, various purifiers and purifying methods for inert gases have been studied in the past.For example, (1) purification in which a rare gas is brought into contact with a getter agent composed of iron and zirconium to remove impurities in the rare gas. Method (Japanese Patent Laid-Open No. 4-160010), (2) a purification method for removing impurities in the rare gas by bringing a rare gas into contact with a getter agent comprising vanadium and zirconium (Japanese Patent Laid-Open No. 5-4809), (3) oxygen And / or an inert gas containing carbon monoxide is brought into contact with an adsorbent containing a porous metal oxide such as a mixed oxide (hopcalite) of copper and manganese to remove the impurity gas (Japanese Patent Laid-Open No. Hei 10). -137530) has been developed.

  In addition, refining the inert gas after purifying the inert gas not only effectively recycles the resources, but also reduces the refilling and pre-treatment of the refining agent. It is also preferable from the viewpoint that the inert gas can be easily supplied continuously. Therefore, for example, (4) a purification method (Japanese Patent Publication No. 50-6440) has been developed in which an inert gas is brought into contact with reduced metallic nickel to remove oxygen contained as an impurity in the inert gas. In such a purification method, the purification agent (metallic nickel) can be regenerated.

Japanese Patent Publication No. 50-6440 Japanese Patent Laid-Open No. 3-12315 Japanese Patent Laid-Open No. 4-160010 Japanese Patent Laid-Open No. 5-4809 JP-A-10-137530

  However, the purification method using the getter agent as described in (1) or (2) above generally requires heating the getter agent when purifying the inert gas, and regenerates the getter agent. Therefore, it is necessary to replace the agent, and there is a disadvantage that the running cost becomes high. In addition, the purifying agent used in the purification methods (3) and (4) originally has a low ability to remove impurities in the inert gas (impurity removal amount per unit amount of the purifying agent), especially the removal of carbon dioxide. The capacity was low and it was necessary to enlarge the purification cylinder. Further, the purification agent used in the purification method (3) has a disadvantage that it is deteriorated by repeated regeneration and the removal ability is further lowered.

  Therefore, the problem to be solved by the present invention is to remove carbon dioxide, oxygen and the like contained as impurities in the inert gas, in particular, the ability to remove carbon dioxide is high, and a small amount of the impurities without heating during purification. Can be removed to a very low concentration, and refinement of an inert gas that can continuously supply a high-purity inert gas easily without reducing the impurity removal ability even if the purification agent is regenerated repeatedly. It is to provide a formulation and purification method.

  As a result of diligent studies to solve these problems, the present inventors have used a purification agent obtained by supporting carbonate and / or bicarbonate on a carrier mainly composed of nickel as a purification agent. The removal ability of carbon dioxide, oxygen, carbon monoxide, hydrogen, etc. contained as impurities in inert gas, especially the removal ability of carbon dioxide is high, and a trace amount of impurities can be removed to very low concentration without heating. The inventors have found that the purification agent is not deteriorated even when the purification agent is regenerated repeatedly, and that the life of the purification agent is remarkably extended, and the inert gas purification agent and purification method of the present invention have been reached.

That is, the present invention is a purifying agent for inert gas, characterized in that a carbonate and / or bicarbonate is supported on a carrier mainly composed of nickel.
The present invention also provides a carbon dioxide contained as an impurity in the inert gas by bringing the inert gas into contact with a purifier formed by supporting a carbonate and / or bicarbonate on a carrier mainly composed of nickel. It is also a method for purifying an inert gas, characterized in that it is removed.

  The purifying agent and the purifying method for an inert gas of the present invention include a purification of an inert gas containing carbon dioxide as an impurity, and at least one selected from oxygen, carbon monoxide, and hydrogen together with carbon dioxide as an impurity. Applicable to purification of inert gas including gas. Moreover, the purifying agent and the purifying method of the inert gas of the present invention are particularly effective in that the purifying agent used for purifying the inert gas can be regenerated and its life can be significantly extended. The inert gas in the present invention is helium, nitrogen, neon, argon, krypton, xenon, or the like.

  In the purifying agent of the present invention, a carrier containing nickel as a main component is used, and carbonate and / or bicarbonate is supported (attached) on the carrier. The carrier mainly composed of nickel is a carrier mainly composed of one or more selected from nickel, a nickel alloy, and a nickel compound, but preferably includes a nickel compound that is easily reduced, such as an oxide of nickel. Further, as a metal component other than nickel, a metal such as magnesium, aluminum, silicon, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, or an oxide thereof is contained in a small amount. Also good. However, the nickel content relative to the entire support is usually 10 wt% or more, preferably 20 wt% or more, more preferably 40 wt% or more, and further, a reduction treatment is performed when purifying the inert gas, The thing which becomes 50 wt% or more is preferable.

  The purification agent carrier in the present invention preferably uses the above nickel compound as a carrier as it is, but the carrier is obtained by adhering a nickel compound to the surface of activated carbon, diatomaceous earth, alumina, silica alumina, aluminosilicate, calcium silicate, or the like. It is also possible to do. For example, after dispersing activated carbon or the like in a solution containing a nickel salt, the support is prepared by evaporating the solution with an evaporator and further drying at about 100 to 200 ° C.

In addition, since various nickel-based catalysts are commercially available, the purification agent carrier in the present invention may be used as it is. The BET specific surface area of the carrier mainly composed of nickel is usually 5 to 500 m ² / g, preferably 10 to 300 m ² / g. In addition, the shape, size, etc. are not limited, but if it is a sphere, it usually has a diameter of about 1 to 10 mm, and if it is a cylinder, it usually has a diameter of about 1 to 10 mm and a height of 2 A size of about 20 mm, other similar shapes, and a size corresponding to this are used.

  In the purifying agent of the present invention, examples of the carbonate and bicarbonate added to the carrier include lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, lanthanum carbonate, sodium bicarbonate, and potassium bicarbonate. , Rubidium hydrogen carbonate, cesium hydrogen carbonate and the like. These may be anhydrous salts or hydrated salts. Of these, one type may be used, or two or more types may be used simultaneously.

The amount of these carbonates and bicarbonates added to the entire refining agent is usually 0.1 to 50 wt%, preferably 0.5 to 30 wt%. When the amount added is less than 0.1 wt%, the ability to remove impurities decreases during purification of the inert gas. Further, it is difficult to support the carrier so that the added amount exceeds 50 wt%.
Although there is no particular limitation on the method of adding the carbonate or bicarbonate to the carrier mainly composed of nickel, a solution containing carbonate and / or bicarbonate is sprayed on the carrier and then heated. The method of drying with can be illustrated. The purifying agent is usually prepared so that the specific surface area is 5 to 500 m ² / g, preferably 10 to 300 m ² / g.

  The method for purifying an inert gas of the present invention is a method for removing carbon dioxide contained as an impurity in the inert gas by bringing the inert gas into contact with the above-described purifying agent. In the present invention, a purifier comprising carbonate and / or bicarbonate supported on a nickel-based carrier is usually hydrogen, carbon monoxide, ether to activate it before use. Reduction treatment with a reducing gas such as alcohols, alcohols, ketones, esters and hydrocarbons. In the reduction, for example, hydrogen or a mixed gas of hydrogen and nitrogen is passed at a temperature of about 100 to 400 ° C. at an empty cylinder linear velocity (LV) of about 1 to 50 cm / sec.

The purification of the inert gas is usually performed by filling the purification cylinder 2 as shown in FIG. 1 with the purification agent 1, performing a reduction treatment, and then passing the inert gas through the purification cylinder 2. In the figure, 3 is a heater and 4 is an inert gas supply line.
In practice, the filling length of the purification agent filled in the purification cylinder is usually 50 to 1500 mm. If the filling length is shorter than 50 mm, the impurity removal rate may decrease, and if the filling length is longer than 1500 mm, the pressure loss may be excessively increased. The hollow cylinder velocity (LV) of the inert gas at the time of purification differs depending on the concentration of impurities in the supplied inert gas and the operating conditions, and cannot be specified unconditionally, but is usually 100 cm / sec or less, preferably 30 cm / sec sec or less.

  The contact temperature between the inert gas and the purifying agent is 100 ° C. or less in terms of the temperature of the gas supplied to the inlet of the purifying agent cylinder, and is usually normal temperature, and does not require heating or cooling. Further, the pressure at the time of contact between the inert gas and the purification agent is not particularly limited, and the treatment can be performed under normal pressure, reduced pressure such as 1 KPa, or pressurized pressure such as 2 MPa (absolute pressure). Is performed under normal pressure to 1 MPa (absolute pressure).

  In the inert gas purification method of the present invention, the regeneration of the purification agent is usually performed by a reduction treatment with a reducing gas such as hydrogen, carbon monoxide, ethers, alcohols, ketones, esters, hydrocarbons and the like. It is. The regeneration of the purifying agent can be performed by passing a reducing gas or a mixed gas of reducing gas and inert gas through a purifying cylinder filled with the purifying agent at a temperature of 150 to 400 ° C. From the viewpoint of further extending the life of the purifying agent, it is preferable to carry out by supplying an inert gas to the purifying agent and then supplying a reducing gas under the above conditions.

  In the inert gas purification method of the present invention, in order to easily and continuously supply a high-purity inert gas, the inert gas is purified by arranging at least two purification lines equipped with a purification agent. It is preferable. FIG. 2 is a block diagram showing an example of a purification line for use therein, wherein 2 is a purification cylinder, 4 is an inert gas supply line, 5 is a purified inert gas extraction line, and 6 is a regeneration gas ( A reducing gas) supply line 7 is a regenerated exhaust gas discharge line. With such a purification line, it is possible to regenerate the purification agent by supplying an inert gas while simultaneously switching each line, and at the same time supplying a regeneration gas to the line after purification. It becomes possible to supply gas continuously and easily.

  By the inert gas purification agent and purification method of the present invention, carbon dioxide and the like contained in the inert gas as impurities are much more than conventional purification methods in terms of impurity removal amount per unit amount of the purification agent. It became possible to remove. In addition, trace amounts of carbon dioxide contained in the inert gas can be removed to a very low concentration without heating, and the ability to remove impurities is reduced even after repeated purification of the purifier. As a result, it was possible to extend the lifetime of the purification agent significantly longer than the conventional purification method.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited by these.

(Preparation of purification agent)
A commercially available nickel catalyst was used as a carrier for the purification agent. This catalyst has a main composition of Ni and NiO, 60 wt% Ni, 5 wt% MgO, 13 wt% SiO ₂ , a specific surface area of 200 m ² / g, a diameter of 2.8 mm, and a height of 2.8 mm. It is a columnar molded body. 96 g of this carrier was immersed in and dispersed in 100 g of an aqueous potassium carbonate solution (potassium carbonate 4 wt%), and then the aqueous solution was evaporated with an evaporator and further dried at 350 ° C. for 5 hours to obtain a purification agent having a specific surface area of 195 m ² / g. Got. As a result of measuring the weight change of the carrier, the amount of potassium carbonate added to the entire purification agent was 3.5 wt%.

(Inert gas purification test)
The purification agent was filled into a stainless steel purification cylinder having an inner diameter of 16.4 mm and a length of 300 mm so as to have a filling length of 100 mm. Next, the temperature of the purification cylinder was raised to 250 ° C., hydrogen was passed at a flow rate of 1000 ml / min for 2 hours to reduce the purification agent, and then the purification cylinder was cooled to room temperature.

  Next, it refine | purified by distribute | circulating nitrogen containing 10 ppm of carbon dioxide as an impurity at normal temperature (20 degreeC) and 0.6 Mpa (absolute pressure) with the flow volume of 13830 ml / min. During this period, carbon dioxide in the outlet gas is analyzed using an atmospheric pressure ionization mass spectrometer (API-MS) at intervals of about 20 minutes, and the time until carbon dioxide is detected is measured. The amount of carbon dioxide removed (ml) was determined. (API-MS carbon dioxide, oxygen, carbon monoxide, hydrogen detection lower limit concentration: 1 ppb) The results are shown in Table 1.

  After the detection of carbon dioxide, the supply of inert gas is stopped, the temperature of the purifying agent is raised to 250 ° C., nitrogen is circulated for 1 hour at a normal pressure and a flow rate of 1000 ml / min. The purified gas was regenerated by circulating a mixed gas (hydrogen 5 vol%, nitrogen 95 vol%) at normal pressure and a flow rate of 1000 ml / min for 2 hours. Thereafter, the purifier was cooled to room temperature, and nitrogen purification was resumed. Table 1 shows the results obtained by repeating the above operation and determining the carbon dioxide removal amount (ml) per gram of the purifying agent.

Examples 2 and 3
In the preparation of the purifying agent of Example 1, the amount of potassium carbonate in the purifying agent was changed to 1.4% and 8.8%, respectively. Prepared.
An inert gas purification test was conducted in the same manner as in Example 1 except that these purification agents were used. The results are shown in Table 1.

Examples 4 and 5
In the inert gas purification test of Example 1, the inert gas was purified in the same manner as in Example 1 except that nitrogen containing 5 ppm of carbon dioxide and nitrogen containing 100 ppm of carbon dioxide were used as the inert gas. A test was conducted. The results are shown in Table 1.

Examples 6-10
In the preparation of the purification agent of Example 1, instead of potassium carbonate, lithium carbonate (addition amount with respect to the entire purification agent: 35 wt%), sodium carbonate (addition amount with respect to the entire purification agent: 23 wt%), lanthanum carbonate (purification agent) Other than using potassium bicarbonate (addition amount to the entire refining agent: 3.5 wt%), sodium hydrogen carbonate (addition amount to the entire refining agent: 3.5 wt%) A purification agent was prepared in the same manner as in Example 1.
An inert gas purification test was conducted in the same manner as in Example 1 except that these purification agents were used. The results are shown in Table 1.

Example 11
In the inert gas purification test of Example 1, the inert gas purification test was performed in the same manner as in Example 1 except that nitrogen containing 20 ppm of oxygen was used as the inert gas. The results are shown in Table 2.

Examples 12 and 13
In the preparation of the purifying agent of Example 11, the amount of potassium carbonate in the purifying agent was changed to 1.4% and 8.8%, respectively. Prepared.
An inert gas purification test was conducted in the same manner as in Example 11 except that these purification agents were used. The results are shown in Table 2.

Examples 14 and 15
In the inert gas purification test of Example 11, the inert gas purification test was performed in the same manner as in Example 11 except that nitrogen containing 10 ppm of oxygen and nitrogen containing 50 ppm of oxygen were used as the inert gas. I did it. The results are shown in Table 2.

Examples 16-20
In the preparation of the purification agent of Example 11, instead of potassium carbonate, lithium carbonate (addition amount with respect to the entire purification agent: 35 wt%), sodium carbonate (addition amount with respect to the entire purification agent: 23 wt%), lanthanum carbonate (purification agent) Other than using potassium bicarbonate (addition amount to the entire refining agent: 3.5 wt%), sodium hydrogen carbonate (addition amount to the entire refining agent: 3.5 wt%) A purification agent was prepared in the same manner as in Example 11.
An inert gas purification test was conducted in the same manner as in Example 11 except that these purification agents were used. The results are shown in Table 2.

Example 21
In the inert gas purification test of Example 1, the inert gas purification test was performed in the same manner as in Example 1 except that nitrogen containing 10 ppm of carbon monoxide was used as the inert gas. The results are shown in Table 3.

Example 22
In the preparation of the purifying agent of Example 21, the purifying agent was prepared in the same manner as in Example 21 except that the amount of potassium carbonate in the purifying agent was changed to 1.4%.
An inert gas purification test was performed in the same manner as in Example 21 except that this purification agent was used. The results are shown in Table 3.

Example 23
In the inert gas purification test of Example 21, an inert gas purification test was conducted in the same manner as in Example 21 except that nitrogen containing 20 ppm of carbon monoxide was used as the inert gas. The results are shown in Table 3.

Example 24
In the inert gas purification test of Example 1, an inert gas purification test was performed in the same manner as in Example 1 except that nitrogen containing 30 ppm of hydrogen was used as the inert gas. The results are shown in Table 3.

Example 25
In the preparation of the purifying agent of Example 24, the purifying agent was prepared in the same manner as in Example 24, except that the amount of potassium carbonate in the purifying agent was changed to 1.4%.
An inert gas purification test was conducted in the same manner as in Example 24 except that this purification agent was used. The results are shown in Table 3.

Example 26
In the inert gas purification test of Example 24, an inert gas purification test was performed in the same manner as in Example 24 except that nitrogen containing 60 ppm of hydrogen was used as the inert gas. The results are shown in Table 3.

Example 27
In the preparation of the purifying agent of Example 1, a purifying agent was prepared in the same manner as in Example 1 except that a sponge-like molded body containing 50 wt% Ni and 50 wt% Al was used.
An inert gas purification test was conducted in the same manner as in Example 1 except that this purification agent was used. The results are shown in Table 3.

Example 28
In the preparation of the purifying agent of Example 1, a purifying agent was prepared in the same manner as in Example 1 except that a ring-shaped molded body containing 30 wt% NiO (Ni: 24 wt%) was used.
An inert gas purification test was conducted in the same manner as in Example 1 except that this purification agent was used. The results are shown in Table 3.

Comparative Example 1
A purification agent was prepared in the same manner as in Example 1 except that potassium carbonate was not added to the carrier in the preparation of the purification agent of Example 1.
An inert gas purification test was conducted in the same manner as in Example 1 except that this purification agent was used. The results are shown in Table 3.

The block diagram which shows an example of the purification line for enforcing the purification method of the inert gas of this invention The block diagram which shows the example of purification lines other than FIG. 1 for implementing the purification method of the inert gas of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refiner 2 Purification cylinder 3 Heater 4 Inert gas supply line 5 Extraction line of refined inert gas 6 Regeneration gas supply line 7 Regeneration exhaust gas discharge line

Claims (10)

  A purifying agent for an inert gas, wherein a carbonate and / or bicarbonate is supported on a carrier mainly composed of nickel.   The purifier for inert gas according to claim 1, wherein the carbonate is lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, or lanthanum carbonate.   The purifying agent for an inert gas according to claim 1, wherein the hydrogen carbonate is sodium hydrogen carbonate, potassium hydrogen carbonate, rubidium hydrogen carbonate, or cesium hydrogen carbonate.   The inert gas purifier according to claim 1, wherein the nickel content is 10 wt% or more of the entire support.   The purifying agent for an inert gas according to claim 1, wherein the amount of carbonate and / or bicarbonate added is 0.1 to 50 wt% of the entire purifying agent. The inert gas purification agent according to claim 1, wherein the purification agent has a specific surface area of 5 to 500 m ² / g.   Contacting an inert gas with a purifying agent comprising carbonate and / or bicarbonate supported on a carrier mainly composed of nickel, to remove carbon dioxide contained as an impurity in the inert gas A method for purifying an inert gas.   The method for purifying an inert gas according to claim 7, wherein the inert gas contains one or more impurities selected from oxygen, carbon monoxide, and hydrogen in addition to carbon dioxide.   The method for purifying an inert gas according to claim 7, wherein the contact temperature between the inert gas and the purifying agent is 100 ° C. or less. The method for purifying an inert gas according to claim 7, wherein the purifying agent after use is brought into contact with a reducing gas under heating to regenerate the purifying agent.

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