CN116240427A

CN116240427A - Getter alloy for purifying nitrogen and inert gas, and preparation and application thereof

Info

Publication number: CN116240427A
Application number: CN202211661498.7A
Authority: CN
Inventors: 刘晓鹏; 尹凯; 徐晓强; 杨志民
Original assignee: GRIMN Engineering Technology Research Institute Co Ltd
Current assignee: GRIMN Engineering Technology Research Institute Co Ltd
Priority date: 2022-12-23
Filing date: 2022-12-23
Publication date: 2023-06-09

Abstract

A getter alloy for purifying nitrogen and inertial gas is prepared from Zr, nb and FeElement composition, nominal composition (Zr) _1‑x Nb _x )yFe _1‑y The alloy composition also contains one or two of rare earth RE (Ce, la) and other additional elements. The alloy is prepared by adopting 99.9 percent of Zr, fe and Nb metal simple substances and 99.5 percent of rare earth elements to carry out induction smelting under the protection of vacuum or inert atmosphere. The alloy has higher H absorption ₂ Capacity and adjustable N ₂ The adsorption capacity can be used for purifying nitrogen and inert gases.

Description

Getter alloy for purifying nitrogen and inert gas, and preparation and application thereof

Technical Field

The invention belongs to the technical field of non-evaporable getter materials, and particularly relates to a getter alloy for purifying nitrogen and inert gases and a preparation method thereof.

Background

The getter alloy can effectively absorb active gases such as H2, CO, CH4, H2O, N2 and the like, and is widely applied to the fields of high vacuum acquisition or maintenance, gas purification, hydrogen-containing isotope tail gas recovery and the like. When the purified gas or the tail gas containing hydrogen isotopes is treated and recovered, the mixed gas passes through a purification column containing a getter material, and the getter alloy in the column selectively absorbs and adsorbs H2, CO, CH4, H2O and the like, thereby achieving the purposes of purifying the gas or recovering the hydrogen.

The Zr2Fe alloy has very low hydrogen adsorption equilibrium pressure (Fusion Engineering and design.1997,36 (4): 471-478) and about 120ml/g hydrogen adsorption capacity. When the alloy is heated to 200-350 ℃, chemical adsorption reaction can be carried out with gases such as CO, CH4, H2O, CO and the like, but the adsorption to N2 gas is slow, and the adsorption capacity is very low, so the alloy is often used for nitrogen purification, trace hydrogen isotope gas adsorption recovery in nitrogen-containing atmosphere and the like. For example, zr2Fe alloy at 350 ℃ and 2.5X10 ⁵ The Pa pressure is used for absorbing and recovering 0.1vol.% and 1vol.% of hydrogen in pure nitrogen, and the recovery efficiency respectively reaches 94 percent and 98 percent (Fusion Science and technology.2017,71 (3): 321-325).

Zr2Fe has low reaction speed and low capacity with nitrogen and does not react with inert gas, so that the method can also be used for recycling hydrogen isotope gas in the inert gas. In order to improve the adsorption efficiency of the alloy to the hydrogen isotope gas, the alloy is generally required to be heated to 350 ℃ to promote the reaction process, and at the moment, the alloy can be subjected to irreversible chemical reaction with CO, CH4, H2O, CO2 and the like besides adsorbing the hydrogen, so that the purification and purification functions of inert gas are realized. However, the Zr2Fe alloy has slow reaction on nitrogen and low adsorption capacity, and is easy to reach a stable nitrogen absorption state, so that nitrogen in inert gas cannot be effectively removed, and the purification purity of the inert gas is reduced. Generally, zr2Fe is selected to be matched with getter alloys such as ZrVFe or ZrC, so that chemical desorption of hydrogen and nitrogen in inert gas is realized, but the mixing proportion and filling state of different types of getter alloys have great influence on the purification effect. When the mixing is uneven, the inert gas may short-circuit through the reaction bed resulting in a higher nitrogen or H2 content in the inert gas. In addition, although almost all getter alloys are capable of absorbing hydrogen, there are significant differences in hydrogen absorption capacity and rate, which can be potentially detrimental to inconsistent inert gas purification performance.

Therefore, a getter alloy which can be conveniently designed according to the purification requirement of nitrogen or inert gas is developed, and the requirement of inert gas purification is met by adjusting the alloy composition to ensure that the getter alloy has high H2 absorption capacity and rate and proper nitrogen absorption capacity; or has high hydrogen absorption capacity and rate and low nitrogen absorption capacity to meet the nitrogen purification requirement, thereby realizing multiple applications of one alloy.

Disclosure of Invention

In view of the drawbacks of the prior art, a first aspect of the present invention provides a getter alloy capable of achieving nitrogen and hydrogen adsorption by alloy composition adjustment, said getter alloy consisting of three main elements of zirconium, niobium and iron, the nominal composition being (Zr _1-x Nb _x ) ₆₇ Fe ₃₃ Wherein 0 is<x≤0.5。

In the invention, the composition of the getter alloy also comprises one or two of rare earth RE (Ce and La) additional elements. The weight of the additional element is (Zr _1-x Nb _x ) ₆₇ Fe ₃₃ 0.5wt.% to 2.0wt.%, preferably 1.0wt.% to 1.5wt.% of the total weight of the three raw materials of the alloy;

in the present invention, the getter alloy powder particle size of the getter alloy is less than 500 μm, preferably less than 300 μm.

In the invention, the nitrogen or inert gas purification requirement is met by adjusting the alloy components to realize the adjustment of the adsorption capacity and adsorption rate of nitrogen and hydrogen.

In a second aspect of the present invention, there is provided a method for preparing the getter alloy according to the first aspect of the present invention, which is prepared by smelting pure elements (preferably bulk or sheet simple substances), wherein the raw materials adopt high-purity Zr, fe, nb metal simple substances with purity greater than 99.9% and rare earth element purity greater than 99.5%. Smelting is performed under vacuum or inert atmosphere protection to avoid oxidation of the alloy. Methods such as arc melting, vacuum induction melting, electron beam melting, and the like may be used. And then grinding the alloy ingot by a mechanical crushing or ball milling method under the protection of argon atmosphere, and sieving to obtain the expected alloy powder, wherein the particle size is generally less than 500 mu m, and more preferably less than 300 mu m.

In the invention, the performance evaluation of the hydrogen and nitrogen of the getter alloy is carried out on a high vacuum workbench by adopting an isovolumetric method, and a stainless steel sample container is separated from a testing system by a valve. 0.5g of getter alloy powder marked with different components is weighed and placed in a stainless steel container with the volume of 20ml respectively, and the container for containing the getter alloy is heated to 673K by an electric heater, vacuumized and activated for 60 minutes (the vacuum degree is better than 1.0x10) ^-4 Pa), then cooling and maintaining at a certain temperature, closing a valve between the sample and the system, closing the system vacuum, respectively charging hydrogen and nitrogen at a certain pressure into the system through an inflation valve, opening the valve between the sample and the system after the pressure is stable, and completely exposing the getter to hydrogen and nitrogen atmosphere at a certain initial pressure. The adsorption of the gas by the getter alloy can lead to the change of the gas pressure in the system, the isothermal kinetic curve of the getter alloy for adsorbing hydrogen and nitrogen can be calculated according to the pressure change value, and the final adsorption capacity of different gases under different pressures can be obtained.

The invention has the advantages that:

the getter alloy has higher hydrogen absorption capacity under the high-temperature condition, and the N2 absorption capacity can be adjusted in a wider range according to alloy components. The getter alloy belongs to the technical field of non-evaporable getter materials, and can be used for purifying nitrogen or inert gas, recycling low-pressure hydrogen in nitrogen or inert gas and the like.

Drawings

FIG. 1 is (Zr) _1-x Nb _x ) ₆₇ Fe ₃₃ -Ce alloy hydrogen adsorption kinetics curves at 603K and 3 KPa.

FIG. 2 is (Zr) _0.95 Nb _0.05 ) ₆₇ Fe ₃₃ RE alloy nitrogen adsorption kinetics curves at 623K and 0.5MPa.

Detailed Description

The following describes the technical scheme of the present disclosure in detail by using specific embodiments and referring to the accompanying drawings.

Example 1

(Zr _1-x Nb _x ) ₆₇ Fe ₃₃ Ce alloy hydrogen adsorption properties. The alloy composition of the getter alloy A, B, C, D, E, F, G is shown in table 1. Specifically, the addition amount of the additional element Ce is kept unchanged at 1.5wt%, and the Nb content is increased from 0.05at% to 33at%. The alloy is formed by induction smelting of Zr, fe and Nb metal simple substance sheets with the purity of more than 99.9 percent and rare earth Ce with the purity of more than 99.5 percent in a water-cooled copper crucible protected by argon atmosphere, and mechanically crushing and screening under the protection of the argon atmosphere to obtain powder with the granularity of less than 300 mu m. After the alloy powder is activated in vacuum, 603K and 3KPa hydrogen adsorption performance tests are carried out, and the dynamic curve is shown in figure 1. As can be seen from fig. 1, the alloy absorbs hydrogen rapidly and reaches saturated absorption, i.e., the absorption capacity increases rapidly with time immediately after the start of the absorption, and then the absorption capacity increases slowly and finally reaches saturated state. Alloys with different Nb content have significant differences in hydrogen adsorption rate and capacity. The increase in Nb content shows a decreasing trend in the hydrogen absorption saturation capacity of the alloy, but the hydrogen absorption rate is increased. For example, the saturated hydrogen absorption capacity of an alloy with Nb content of 3.4at percent is 85ml/g, and the hydrogen absorption speed is faster in the first 10 minutes, but the alloy can absorb the hydrogen for saturation within 35 minutes. The saturated adsorption capacity of the Nb alloy containing 33at percent of hydrogen is 37.6ml/g, and the saturation of hydrogen absorption is achieved within 5 minutes. All alloy saturated hydrogen absorption capacities are shown in table 1.

TABLE 1

Example 2:

alloy A, B, C, D, E, F, G of example 1, which had the same composition and preparation process, was used to conduct a 623K nitrogen adsorption performance test, with an adsorption nitrogen pressure of 0.5MPa. The nitrogen adsorption kinetics curves are shown in figure 2. As can be seen from FIG. 2, the absorption kinetics of the alloy for N2 is significantly different from that of FIG. 1. N2 adsorption kinetics show parabolic shape, and the adsorption rate increases faster with the increase of Nb content, for example, the nitrogen absorption capacity of 33at% Nb alloy reaches 4ml/g in 10 minutes, and the nitrogen absorption capacity is 1.53ml/g higher than that of 0.05at% Nb alloy for 120 min. The nitrogen absorption capacity of the alloy with the Nb content of 3.4at percent for 120min reaches 3.5ml/g, which is more than twice that of the alloy with the Nb content of 0.05at percent. Unlike the hydrogen absorption energy which reaches saturation faster, the alloy nitrogen absorption capacity and rate increase with the increase of Nb content, but does not reach saturation even at 120min, thus indicating that the alloy is a continuous slow process for nitrogen absorption. Since the alloy still did not reach the saturation capacity after 120min of nitrogen absorption, the statistics of the N2 absorption capacity of 120min are shown in table 2 for comparison.

TABLE 2

Sample of	N2 absorbing capacity (ml/g) for 120min
		Alloy A	1.53
Alloy B	2.36
		Alloy C	2.76
Alloy D	3.50
		Alloy E	4.25
Alloy F	6.95
		Alloy G	8.56

Example 3:

the added amount of the additional element RE is related to the characteristic of hydrogen absorption and nitrogen absorption of the alloy. The composition of the getter alloy H, I, J, K, L, M, N, O, P, Q, R, S is shown in Table 3, and is specifically an alloy (Zr _0.95 Nb _0.05 ) ₆₇ Fe ₃₃ The RE element is added and the total RE content is regulated to be 0.5at% to 2.0at% unchanged. The alloy is prepared by induction smelting Zr, fe and Nb metal simple substance slices with the purity of more than 99.9 percent and rare earth La and Ce with the purity of more than 99.5 percent serving as raw materials in a water-cooled copper crucible protected by argon atmosphere. Mechanically crushing the alloy ingot under the protection of argon atmosphere, and sieving to obtain powder with the granularity less than 300 mu m. After vacuum activation, the alloy powders were subjected to 603K and 3KPa hydrogen and 623K and 0.5MPa nitrogen adsorption performance tests, respectively, and the results are summarized in Table 3. It can be seen that, when the weight of the added rare earth element increases to 1.5wt%, the hydrogen absorption capacity of the alloy reaches the maximum value, and then the initial drop decreases with the increase of the rare earth amount, regardless of whether La or Ce is added; the alloy added with the rare earth element Ce has higher hydrogen absorption capacity than La, and the hydrogen absorption capacity is centered when La and Ce are mixed and added. The change trend of the nitrogen adsorption capacity along with the content and the type of rare earth elements is similar to the hydrogen absorption performance.

TABLE 3 Table 3

As can be seen from the results of the above examples and the accompanying drawings, increasing the amount of Nb in the alloy decreases the hydrogen absorption capacity of the alloy hydrogen, but increases the rate, which is advantageous for increasing the H2 absorption recovery rate in the inert gas. Meanwhile, the adsorption capacity of the alloy to nitrogen increases along with the increase of the Nb content, and the alloy has the capability of removing the nitrogen by reaction, so that the alloy with high Nb content can be used for purifying inert gas and removing hydrogen and nitrogen in the inert gas.

When used as nitrogen purification, the Nb content alloy below 3.4at percent has small nitrogen absorption capacity and rate (such as 3.4ml/g for 120 min) even under the nitrogen pressure of 350 ℃ and 0.5MPa, but has 88ml/g for 3KPa hydrogen and higher hydrogen absorption reaction rate, so that the low Nb content alloy can be used for nitrogen purification or recovery of hydrogen in nitrogen.

The alloy for purifying nitrogen or inert gas has the advantages that after La or Ce rare earth elements are added, the hydrogen absorption capacity and the nitrogen absorption capacity of the alloy are increased along with the increase of the rare earth content, and the maximum value of the hydrogen absorption capacity and the nitrogen absorption capacity of the alloy is reached when the addition amount of 1.5 weight percent is reached; the rare earth element Ce is more beneficial to the improvement of the performance than La under the condition of the same added weight.

Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any adaptations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the claims of the present application.

Claims

1. A getter alloy for purifying nitrogen and inert gases is characterized in that the alloy is composed of three elements of zirconium, niobium and iron, and the atomic percentage of the getter alloy is (Zr _1-x Nb _x ) ₆₇ Fe ₃₃ Wherein 0 is<x≤0.5。

2. According to claimThe getter alloy according to claim 1, wherein the getter alloy composition further comprises rare earth RE: one or two of Ce or La additional elements, the weight of the additional elements being (Zr _1-x Nb _x ) ₆₇ Fe ₃₃ 0.5wt.% to 2.0wt.% of the total weight of the three materials of the alloy.

3. Getter alloy according to claim 2, wherein the weight of the additional element is (Zr _1- _x Nb _x ) ₆₇ Fe ₃₃ 1.0wt.% to 1.5wt.% of the total weight of the three raw materials of the alloy.

4. According to claims 1 to 3 (Zr) _1-x Nb _x ) ₆₇ Fe ₃₃ -RE getter alloy, characterized in that said getter alloy powder has a particle size smaller than 500 μm, preferably smaller than 300 μm.

5. A method for preparing a getter alloy according to claim 1, wherein the getter alloy is prepared by smelting pure elements, the purity of the metal elements of high purity Zr, fe and Nb is more than 99.9%, and the purity of rare earth elements is more than 99.5%. Smelting is carried out under vacuum or inert atmosphere protection, and then grinding is carried out on the alloy ingot under argon atmosphere protection by a mechanical crushing or ball milling method, and the desired alloy powder is obtained by sieving.

6. The process according to claim 5, which gives an alloy powder having a particle size of less than 500. Mu.m.

7. The process according to claim 6, wherein the alloy powder has a particle size of 300 μm or less.

8. Getter alloys obtained by the process according to any of claims 5 to 7, for the recovery of gases containing hydrogen from nitrogen and inert gases or for the high-temperature purification applications of nitrogen and inert gases.