JPS6230127B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for removing impurity gases contained in a rare gas and improving the purity of the rare gas. Types of rare gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). Targets gas. Currently, rare gases are used in large quantities in various industrial fields such as metals, electronics, and chemicals, and there is a demand for rare gases of higher purity in order to improve product reliability. Accordingly, demand for high-purity rare gases is also increasing. The present invention provides a purification method that can easily obtain this high-purity rare gas with good quality. Conventionally, regarding the purification method of these rare gases,
There are absorption methods, adsorption methods, diffusion methods, cooling separation methods, chemical reaction methods, etc., and these methods were used depending on the purpose of purification and the difference in purification conditions. Among these methods, the most widely used method is the adsorption method, in which Pd-based catalysts, Ni-based catalysts, zeolite-based catalysts, etc. are mainly employed. These catalysts are relatively expensive, and inexpensive catalysts have problems with their adsorption ability, regeneration method, etc., and a cheaper and easier to handle method for purifying rare gases is desired. Although the purification method according to the present invention also belongs to the adsorption method, it is a new purification method that uses a powder that has been subjected to at least one hydrogenation and dehydrogenation process of a hydrogen storage alloy as an adsorbent. This solves the above problems. Metals that form hydrides, such as Ti, Zr, and Ca, have been used as drying agents for gases and for removing oxygen, but they have been difficult to manufacture, and have had problems in terms of cost and properties. The present invention does not focus on these metals alone, but
This method solves the above problem by using an alloy powder known as an alloy for hydrogen storage, and in this respect it is also a completely new purification method. The present inventors found that among the metal materials for hydrogen storage,
Alloy powders such as Ti-Mn-based, Ti-Fe-based, rare earth-Ni-based, etc. can be used to remove impurity gases in rare gases, such as O ₂ , N ₂ ,
It has been found that it is highly effective in adsorbing and removing CO, CO ₂ , CH ₄ , H ₂ O, etc. and improving the purity of rare gases.
More specifically, after creating a hydrogen storage alloy, it is mechanically pulverized or subjected to a hydrogenation reaction in a high-pressure hydrogen atmosphere to produce a metal hydride. In this case, the metal hydride is automatically pulverized by the hydrogenation reaction. The hydrogenated metal hydride powder is further subjected to a dehydrogenation reaction to produce an alloy hydride powder for gas adsorption.
In order to improve the adsorption properties, this metal hydride powder can be made into a fine powder by repeating a series of hydrogenation and dehydrogenation reactions two or more times or by mechanically crushing it in an inert atmosphere. is also effective. The alloy hydride powder obtained in this way is filled into a holding container as shown in Figure 1, which is used as a purifier, and a raw material rare gas is continuously introduced from one side to effectively purify the alloy hydride powder. bring into contact. The purified rare gas obtained from the outlet side of the purifier was compared with the raw material rare gas by purity analysis. Purity analysis is
The standard method specified by Japanese Industrial Standards (JIS) was used. As a result, compared to the raw noble gas, the purified noble gas contains O ₂ , N ₂ , CO, CO ₂ , CH ₄ ,
It was found that all impurity gases such as H ₂ O were significantly reduced, and the purification effect of rare gases was high.
The alloy powder has adsorption properties to some extent even if the alloy is mechanically pulverized as it is without hydrogenation treatment, but it is preferable to further promote activation and improve the adsorption properties by subjecting it to hydrogenation or dehydrogenation treatment. I can do it. The rare gas purification method according to the present invention has the following features. In other words, (1) it has a very high adsorption capacity for impurity gases and can remove all impurity gases at the same time; (2) it does not require a complicated adsorption process, making it easy to configure and operate the associated purification equipment. , (3) the price of the adsorbent is relatively low, and (4) the regeneration of the adsorbent is relatively easy. To explain these characteristics in more detail, first
Regarding adsorption capacity (1), purity can be improved to the extent that it is almost difficult to detect impurity elements in purity analysis, and it can be achieved with one type of adsorbent without selecting the impurity to be removed. In addition, regarding the adsorption process (2), a high purification effect can be obtained simply by passing the rare gas to be purified, so the equipment configuration, operation, and maintenance are extremely easy compared to conventional methods. For example, it has traditionally been very difficult to remove N ₂ from rare gases, but according to the method of the present invention, it can be easily removed because the adsorbent has a strong adsorption ability for N ₂ . It becomes possible. In addition, the price of (3) is lower than that of conventional products because no expensive materials are used and the manufacturing process is easy. The adsorbent shown in (4) can be easily regenerated by normal heating and degassing treatment without impairing the adsorption properties. The alloy is easy to crush, and through a series of hydrogenation and dehydrogenation reactions,
It is thought that the fact that the degree of pulverization is extremely large compared to conventional single particles is the reason for its excellent adsorption properties. In fact, among hydrogenation storage alloys, Ti has a high degree of pulverization due to hydrogenation reaction.
Ti--Mn alloys belonging to the MgZn type ₂ type, which has a hexagonal crystal structure mainly composed of Mn and Mn, had better adsorption characteristics than other Ti--Fe alloys. The rare gas purification method of the present invention is basically to fill a powder holding container 1 as shown in FIG. 1 with alloy powder 2 so as to contact the rare gas as effectively as possible. Various applications are possible depending on various conditions such as the amount of purified gas and the degree of purification. For example, for the purpose of further improving refining capacity,
As shown in the figure, there is a method in which the purification apparatus shown in FIG. 1 is made into multiple stages. The quality of the rare gas can be further improved by a multi-stage purification method as shown in FIG. Next, as a specific example of _{the present invention, a purification method will be described in which a TiMn 1.5 alloy} is used as the alloy hydride and Ar gas is used as the rare gas. MgZn ₂ type TiMn _1.5 , one of _the hydrogen storage alloys
An alloy is created by a method such as arc melting, and this is
It was mechanically ground to a size of ~20 meshes and hydrogenated in _{a closed vessel to obtain TiMn 1.5 H 2.45 .} After repeating hydrogenation several times, this hydride was subjected to vacuum degassing treatment at high temperature to obtain an adsorbent. This dehydrogenated TiMn _1.5 alloy had been turned into fine powder, mostly from several microns to several tens of microns, by the hydrogenation _reaction . An appropriate amount of this Ti--Mn alloy was filled into a powder holding container 1 made of stainless steel as shown in FIG. In addition, the Ar gas, which is the purified gas, flows smoothly and is effectively used as alloy powder 2.
A sponge-like porous alloy was simultaneously filled into the container 1 so as to be in contact with the Ti--Mn alloy. Further, as shown in FIG. 1, a scattering prevention filter 3 made of combustion metal and having a finer hole diameter was arranged at the entrance and exit of the container. By creating a purification device as described above, on the other hand, raw Ar gas containing relatively more impurities is continuously fed into the purification device, and the Ar gas obtained through the purification device is treated as purified Ar gas. The purity was analyzed by the following method. The following table shows the raw materials
An example of impurity analysis results for Ar gas and purified Ar gas is shown in comparison.

[Table] As can be seen from the table, the TiMn _1.5 alloy exhibits high adsorption capacity for all impurity _gases . Next, as a second example, the effects of a multistage purification method in which five purification apparatuses according to the method of the first example are arranged in series with respect to the gas flow as shown in FIG. 2 will be described. The raw material Ar used was the same as in the first example, but the purified Ar gas obtained was O ₂ <
0.1ppm, _N2 ＜1ppm, CO＜0.1ppm, CO2 _＜
The results showed that all impurities were below the detection limit of the analyzer: 0.1 ppm, CH ₄ <0.1 ppm, and H ₂ O <1 ppm. Accordingly, it can be said that the multistage purification method is an extremely effective method. In the example, purification of Ar gas was explained, but purification of rare gases other than Ar and gases other than TiMn-based alloys are also possible.
Similar effects can be obtained with respect to the adsorption capacity of TiFe-based alloys, LaNi ₅ -based alloys, etc. However, Ti−
Mn-based alloys were the best among these alloy materials. As described above, the rare gas purification method of the present invention using alloy powder as an adsorbent uses relatively inexpensive materials, has a very simple structure and operation, and has an excellent purification effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a purification apparatus showing the rare gas purification method of the present invention, and FIG. 2 is a diagram showing a multistage purification method. 1... Container, 2... Alloy hydride powder.

Claims (1)

[Claims] 1. In a method for removing impurity gases contained in a rare gas, a powder obtained by hydrogenating and dehydrogenating a hydrogen storage alloy at least once is filled into a container having a sealable opening. A method for purifying a rare gas, characterized in that a raw material rare gas is introduced into the container, and impurity gases are adsorbed and removed by the powder to obtain a highly pure rare gas. 2. The rare gas purification method according to claim 1, wherein the rare gas is caused to flow in series through the plurality of containers. 3 The powder is MgZn type ₂ whose main components are Ti and Mn.
The method for purifying a rare gas according to claim 1 or 2, which is a Ti-Mn alloy hydride powder.