JPS6020323B2 - Nitrogen gas purification method - Google Patents

Description

Detailed Description of the Invention The present invention removes impurity gas contained in nitrogen gas,
The present invention relates to a method for improving the purity of nitrogen gas.

Nitrogen gas is currently used in large quantities in various industrial fields such as metal, electronics, and chemistry, and higher purity nitrogen gas is desired from the standpoint of improving product reliability. Therefore, demand for high-purity nitrogen gas is also increasing. The present invention provides a purification method that can easily obtain high-purity nitrogen gas with good quality. Conventionally, methods for purifying this nitrogen gas include absorption methods, adsorption methods, diffusion methods, cooling separation methods, and chemical reaction methods, and these methods have been used depending on the purpose of purification and differences 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, and the like are mainly employed as adsorbents.

These catalysts are relatively expensive, and inexpensive catalysts have problems with their adsorption capacity, regeneration method, etc., and a cheaper and easier to handle method for purifying nitrogen gas is desired. The purification method according to the present invention also belongs to the adsorption method, but it is a new purification method that uses a powder that has been subjected to at least one hydrogenation and dehydration process of a hydrogen storage alloy as an adsorbent. This solves the above problems.

Metals that form hydrides, such as Ti, Zr, and Ca, are used as drying agents for gases and for removing oxygen, but they are difficult to manufacture and have problems in terms of cost and properties.

The present invention solves the above problems by using powders of alloys known for hydrogen storage instead of these metals alone, and is a completely new refining method in this respect as well. The present inventors found that among hydrogen storage metal materials, Ti-Mn-based,
Alloy powders such as Tj-Fe-based and rare earth-Ni based impurity gases in nitrogen gas, such as 02, C0, C02, CH
4. It was found that it was highly effective in adsorbing and removing nitrogen gas and improving the purity of nitrogen gas.

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 powder for gas adsorption. In addition, in order to improve the adsorption properties of this metal powder, it is also effective to repeat the series of hydrogenation and dehydrogenation reactions two or more times, or to mechanically crush it in an inert atmosphere to make it into a fine powder. be.

The alloy powder obtained in this way is packed into a holding container as shown in Figure 1 to form a purifier, and raw material nitrogen gas is continuously introduced from one side to effectively contact and pass through the alloy powder. .

The purified nitrogen gas thus obtained from the outlet side in FIG. 1 was compared with the raw material nitrogen gas by purity analysis. Purity analysis was carried out by the usual method specified by Japanese Industrial Standards (JIS) and the like. As a result, compared to the raw nitrogen gas, the purified nitrogen gas had significantly reduced impurity gases such as 02, C○, C02, C ratio, and 20%, indicating that the purification effect of nitrogen gas was high. I put it out.

Alloy powder has adsorption properties to a certain extent even if the alloy is mechanically powdered without hydrogenation treatment, but it is preferable to further promote activation by subjecting it to hydrogenation or dehydrogenation treatment to improve adsorption properties. can be increased. Furthermore, whether the hydrogenation and dehydrogenation treatments are performed in a purifier as shown in Figure 1, or whether they are performed in a separate container and then filled into the purifier, the adsorption properties will be the same. Met. Note that the present inventors have already proposed a method using alloy powder for purifying hydrogen gas and rare gas.

Of these, the purification of hydrogen gas is fundamentally different from the present invention in that hydrogen gas is occluded in an alloy to form a metal hydride, and hydrogen obtained through a hydrogen release reaction is used as purified gas. Furthermore, regarding the method for purifying rare gas, nitrogen gas in the rare gas can also be removed as an impurity gas, and it was expected that the purification of nitrogen gas according to the present invention would be technically difficult. However, when confirmed experimentally, although some of the main gas, nitrogen gas, is adsorbed and removed, other impurity gases of 02, C0, C02, C ratio, and 20 can be sufficiently adsorbed and removed. After seeing this, I proposed a method for purifying nitrogen gas.
The method for purifying nitrogen gas 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; ■ It does not require a complicated adsorption process, so the configuration and operation of the accompanying purification equipment is easy; '3' Examples include that the price of the adsorbent is relatively low, and that the '4' adsorbent can be regenerated relatively easily. To explain these characteristics in more detail, first of all, regarding the adsorption capacity of [1'], it is possible to improve the purity to the extent that it is almost difficult to detect impurity elements in purity analysis, and it is possible to improve the adsorption capacity of one type of impurity without selecting the impurity to be removed. This can be achieved with adsorbents. Regarding the adsorption process '2', a high purification effect can be obtained simply by passing the nitrogen gas to be purified, so the equipment configuration, operation and maintenance are extremely easy compared to conventional ones. Also, the price of '3' is lower than that of conventional products because it does not use expensive materials 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 the extent to which it is pulverized through a series of hydrogenation and dehydrogenation reactions is extremely large compared to conventional simple hydrides, which is thought to be the reason for its excellent adsorption properties. Conceivable.

In fact, among alloy materials, MgZ-type Ti-Mn, whose main components are Ti and Mn, has a high degree of particle formation due to hydrogenation reaction.
The adsorption properties of the alloys were better than those of other Ti--Fe alloys. The nitrogen 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 come into contact with nitrogen gas as effectively as possible. Various applications can be considered depending on various conditions such as the degree of purification and the amount of gas.

For example, in order to further improve the purification capacity, there is a multi-stage method, as shown in FIG. 2, in which a plurality of the purification apparatuses shown in FIG. 1 are provided and arranged in series with respect to the flow of nitrogen gas.

The quality of nitrogen gas can be further improved by this multi-stage purification method. Next, as a hydrogen storage alloy, TIMn, . The refining method when using No. 5 alloy will be explained.

TIMn, whose crystal form belongs to the MgZn2 type with a hexagonal system. 5
An alloy is prepared by a method such as arc melting, mechanically pulverized to a size of 5 to 20 mesh, and hydrogenated in a closed container to form TIMn, . I got 2.45 on the 5th.

This hydride was dehydrogenated, and after repeating hydrogenation and dehydration, it was subjected to vacuum degassing treatment at high temperature to obtain an adsorbent. This dehydrated TIMn, . Most of Alloy No. 5 was turned into fine powder from several microns to several tens of microns by the hydrogenation reaction. An appropriate amount of this Ti-Mh alloy was filled into a powder holding container 1 made of stainless steel as shown in FIG. Note that a sponge-like porous metal was simultaneously filled into the container 1 so that the purified nitrogen gas flowed smoothly and effectively contacted the Ti-Mh alloy that was the alloy powder 2. Further, as shown in FIG. 1, a powder scattering prevention filter 3 made of a compacted metal having a finer hole diameter was placed at the entrance and exit of the container. Create a purification device like the one above,
On the other hand, the raw material nitrogen gas containing relatively more impurities was continuously fed into a purification device, and the nitrogen gas obtained through the purification device was treated as purified nitrogen gas, and the purity of each gas was analyzed by a general method.

The following table shows a comparison of an example of the results of impurity analysis of raw nitrogen gas and purified nitrogen gas. As can be seen from the table, TIMn,
．． No. 5 shows high adsorption ability for any impurity gas.

Next, as a second example, the effects of a multi-stage 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 nitrogen gas used was the same as in the first example, but
The purified nitrogen gas obtained is 0.1 traces of Q, 0.1 traces of CO, 0.1 traces of CO2, 0.1 traces of CH4, and all impurity gas components are detected by the analyzer. The result was that it was below the limit. Therefore, it can be said that the multistage purification method is an extremely effective method. In this way, the purification method of the present invention absorbs nitrogen gas, but Q, C0, C02,
Since 40, CM, etc. are preferentially adsorbed and removed, the purification effect is great. In addition, Ti- other than Ti-Mn alloys
Almost the same effects, such as the ability to adsorb impurity gases, were obtained with Fe-based alloys and La-Ni-based alloys.

However, the Ti-Mn system was the best among these alloy materials. They also investigated the purification effect of a mixture of nitrogen gas with argon or a rare gas such as helium, and found that similar effects could be obtained. As described above, the nitrogen gas purification method of the present invention, which uses hydrogen storage alloy powder as an adsorbent, uses relatively inexpensive materials and has an excellent purification effect with a very simple configuration and operation. be.

[Brief explanation of the drawing]

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

Claims (1)

[Claims] 1 In a method for removing impurity gases contained in nitrogen gas, a powder that has been subjected to at least one hydrogenation and dehydrogenation process of a hydrogen storage alloy is filled into a container with an opening, and the raw material nitrogen gas is A method for purifying nitrogen gas, which is characterized by purifying nitrogen gas by passing it through a container.