JPS58104605A - Separation of hydrogen from gas mixture and hydrogen diffusing membrane used therein - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention describes a method for separating hydrogen from a gas mixture by diffusion at high temperature through a non-porous membrane laminated on the primary side with a palladium alloy, and The present invention relates to a hydrogen-diffusion membrane made of sand and a non-porous material which is selectively permeable to hydrogen and laminated with a palladium alloy on the hydrogen inlet side, carrying out the method.

It is known to separate hydrogen from K by diffusion through palladium (in conjunction with its cathodic deposition from the gas mixture or electrolyte). t'#: Diffusion walls made of other hydrogen-permeable materials are already known, on which palladium or palladium alloys are laminated only on the gas supply side or only when loaded with a gas mixture (U.S. patent no. 440s No. 571), as an example of such a thin next-side palladium alloy layer (on the flL material).
The palladium silver layer must contain a value of 096 or less, and a value of 111C1G to 50-. To promote diffusion, the heat-like wall must be used at a high temperature of about 820 υ - preferably 150-260°C. Furthermore, a pressure difference of at least about 1 bar, in particular not more than about 100 par, between the inlet side and the outlet side must be maintained.

The nine membranes laminated with palladium or palladium alloys are subjected to long-term operation at high temperatures, and the palladium layer or palladium alloy layer on the gas supply side is diffused into the main membrane material.

Therefore, the palladium laminated O has the disadvantage that the protective action and the defusing action are either neglected or ineffective.

For these reasons, the present invention provides a method for diffusing hydrogen and a hydrogen-diffusion membrane that can be used even at high temperatures and for long periods of time using this method. It is to be.

The characteristics of the 1'iK film developed for this purpose are that steel, silver or yttrium are present as alloy partners in the palladium alloy stack with ≥45 atoms.
1 Cu or ≧60 atoms - 1 Mul or ≧7 atoms - 1! and that the membrane itself has a concentration of the respective alloying partner Cu, Mu-4-4, in a concentration that is at least 11 in equilibrium with the palladium stack.

This membrane has an equilibrium concentration of membrane substances, especially steel.

Due to saturation with one of the metals of the chain, yttrium, the composition of the nine layers containing palladium does not change over time, i.e. its concentration does not fall below a predetermined minimum concentration. .

Cu, Mut or! at least in the above amount! Palladium prepared into an alloy with
On the other hand, if there is less steel or silver or yttrium in the stack, the movability of palladium increases and it likewise diffuses into the wall. must represent a steel with at least 45 atoms, in which case it is advantageous for the alloy to consist of 45 to 72 atoms of Cu and the balance Pa.

The number of layers that meet silver is 50~-. Contains 75 atoms of mul-
,: In the case of a laminated layer containing 5* yttrium, the yttrium ratio is 7.1 to 16.4 for Pa/Y-alloy.
It is an atom. Such a P(1/Y layer) is excellent in that it has excellent permeability for hydrogen.

The theoretically high diffusion rates of hydrogen and hydrogen isotopes within tantalum and/or niobium make these materials the most suitable main membrane materials. Steel and silver also dissolve poorly in these substances and form mixed crystals with them. Although palladium itself is dissolved in these materials, alloy K11m in the above amounts with steel or chain
The palladium alloy remains unchanged on the wall surface. These palladium alloys have a known high hydrogen-diffusion coefficient and favorable water 1AlIF dissolution. Steel is superior to pots as an alloying partner in technical equipment.

In fact, in the O experiment, about 55 atoms of steel and 45J [
Child-〇ba:, consists of radium and gas side, ・',',
1lll: K on tantalum and on niobium (each of which is saturated with steel at working temperature) with 1.5 μm
It was confirmed that the layer with a thickness of rounding to prevent the diffusion phenomenon between metals from occurring at the angle of 180° to 450°.
used at °C.

During the long-term experiment, ~14mQPICu (4
0 atoms s: 60 atoms 96) A tantalum plate with a thickness of 91 cm, which was laminated with Cu and saturated with Cu at 400 υ, was heated for 4000 hours.
After being left in vacuum at 0° C., subsequent metallographic tests revealed that the stacked and diffused structure still remained completely intact.

? -0 rounding to build a diffusion wall, 1■ tantalum slope O,S,
S steel and then evaporated with 0.5μ palladium. The saturation of the membrane itself increases over a long period of time.
A natural circle in the time domain. However, it is advantageous to heat to a somewhat higher temperature (below about 400 DEG C.) for a short period of time at the beginning of the experiment, in order to differentiate the saturation of the base materials at the working temperature and their mutual diffusion at the same moment of lamination.

It is advantageous if the gas-side surface is additionally activated in a known manner (INIK metal cutting) in such a way that hydrogen absorption and tritium absorption are not inhibited by the absorbed gases of the primary gas mixture. For normal activation, W, V
ielstich arrival [11r@nnstoffels
m@nte (nuclear fuel) J 1965 V@rlag
Published by Ch@mie, see the description on pages 68 and below.

Additionally, an alloy of the type, i.e., this alloy is also used on the gas side KCu
/Pi layer, extremely small H, /H applied in gas phase -n〒R (high temperature gas reactor)
It is also known that alloys exist which have better hydrogen and thorium permeability properties for T-partial pressure than, for example, pure tantalum. Furthermore, these alloys have the advantage that they do not require additional activation at high temperatures.

At high temperatures above about 400'oC, films containing a high proportion of tantalum and/or niobium in addition to vanadium and titanium, and which can additionally be made of highly selective steels or alloys optionally alloyed with silver, are used as membranes. It is advantageous to use.

These alloys have the corrosion and S! It is similar to alloys having superior properties and containing at least SO-type tantalum by weight 1, especially about 68-70 wt. In addition, these alloys include titanium of 1o~3°Xt-, 5~1owt-
of vanadium and 0.5 to 3 wt. of nickel. It has been found that these alloys do not exhibit any brittleness phenomena even when saturated with steel, as compared to the addition of nickel.

The type of this alloy is special K, which is found in high-temperature nuclear reactors and has approximately 450
Advantageously used as membrane materials for the separation of Hv'HT (at very low partial pressures) from primary circulating gas mixtures at temperatures of ~60° C. e.g. TiO,
5, TIL”O, IS, Cu Ool, V @, 1
The atomic alloy was fII-fused at approximately 2000 t) under argon. In this case, a small portion of the added steel was not absorbed but evaporated. This alloy has a high solubility in hydrogen and does not form a hydride phase at 300°C or above in the pressure range below 1 bar, e.g. °C - isothermal and the following values were obtained: P 10-'10-'10-' 1
At 0-'500℃-isothermal, the following pleasures can be obtained.
2,5.10-' (in the above table, n is the number of dissolved hydrophilic bulk atoms per metal atom, P is the hydrogen partial pressure measured in one equilibrium/b
t-represent. ) This alloy is also a step above hydrogen (for example, pure metal mental, niobium or vanadium).

Only has a high dissolution ridge. Although the hydrogen diffusion coefficient is small, the transmittance can be greatly improved by changing the metal ratio. In tests using scorching heat treatment at 600°C, Cu7/P on the gas side
In this layer and this layer, intermetallic diffusion cannot occur between lines.

The tantalum and small proportion of titanium contained in the above alloys can also be replaced with up to 25% by weight of niobium. Although it is not so advantageous for the purpose of nuclear technology, it is also possible to replace a proportion of copper with silver.

Based on the oxidation phenomenon, K, which suppresses the deterioration of the effect of the diffusion membrane, has a 93-layer structure with an internal hydride-containing melt (as an intermediate layer) that is continuously regenerated as the membrane itself. provided. In the case of such a three-layer structure, the alkali metal hydride or alkaline earth metal hydride is contained in the narrow gap formed between the two completely exposed diffusion membranes described in detail above. It is advantageous to use a melt of 4IK lithium hydride together with its halide as a eutectic melt. 24
The mixture of Li1i and lithium iodide has a mole % of 5
A mixture of 30 molar LiH and lithium bromide melts at 91°C, a mixture containing the corresponding chloride with 54 molar LiH melts at 496°C. These melts are known as KM? ), and at the same time, in this case, a film as thin as possible, about 80 to 200 μm, especially about 100 μm thick, can be used without containing oxygen even during hours of work. This embodiment is particularly advantageous if the downstream gas mixture contains water at a partial pressure of several bars. The pressure difference in the gas mixture versus pure hydrogen on the secondary side results in a rounding driving force for the hydrogen permeation through both membranes and the melt. The thickness of the molten intermediate layer containing hydride is about 10 to several 100711 m, 50 to %
It is 100111 mm.

The attached figure 1 is a schematic diagram of a diffused WXO structure as shown above, saturated with copper, # or yttrite, comprising a palladium-alloy layer 1 and a melt-intermediate layer 3 on a nine-layer substance 2,2'. be.

Practical application of membranes according to the invention consisting of a membrane material saturated with Cu, Muf or I with a palladium steel layer or a badium silver layer or a palladium yttrite layer, particularly at high temperatures, Various difficulties arise in carrying out the work and in separating the very small amounts of hydrogen - in the form of lighter hydrogen or its isotopes, which are present, for example, in the primary cooling gas of a nuclear reactor. This is because - over a long period of time - small amounts of impurities, including water vapor or oxidizing compounds in the secondary or secondary gas chambers, can cause various disturbances, such as having a correspondingly suppressive effect on diffusion or reducing the diffusivity. This is because oxide layer-forming products are formed which have a disadvantageous effect.

Therefore, in Pd1r or in PdCu or in p
It is advantageous to contact the nine films laminated with ay on the vertical side with a melt containing an alkali metal and/or an alkaline earth metal. The affinity of this melt for hydrogen is greater than that of the stacked membranes and the hydrogen bonding partners on the primary side, and this melt has an affinity for alkali hydrides and/or alkaline earth metal hydrides &! In the form of a suspension, it is formed in dissolved form.

Melts containing alkali metals and/or alkaline earth metals can be inhibited by the presence of calcium in the secondary @, as well as by the presence of calcium, with an excessively effective effect on the rate of hydrogen permeation through the wall. It serves to suppress electrification of the wall material by hydride formation, such as zirconium hydride, or by a wide variety of tantalum hydride formations, which can be suppressed by alkali metals. At the same time, this melt prevents the formation of inhibiting layers, such as oxidized layers, on the outlet side of the wall.

A factor in selecting a melt is its affinity for hydrogen as its primary forming partner (i.e., typically primarily H2 or HT).

Affinity (hydrogen itself present in the primary gas)
Make sure that the size is also large.

The separation of hydrogen from the gas mixture according to the invention is achieved by providing a diffusion wall in the form of an exchange wall of a heat exchanger, in particular in the form of a plate heat exchanger, in which the hydrogen is separated from the gas mixture. The gas mixture that absorbs the diffusing hydrogen and the melt that absorbs the diffusing hydrogen move in particular in countercurrent to each other along the diffusion wall in the primary and secondary layers, the melt then passing, for example, in a thin layer across a narrow gap. It is then charged with hydrogen and then guided through a suitable regenerator and recycled again.

Figure 2 of the accompanying drawings is a schematic representation of the structure of a diffusion 2 with a palladium alloy layer 1 on the melt 4 and gas inlet bounded by a secondary plate.

Some embodiments of the invention will be described below.

1. Based on affinity for hydrogen, about 1 mb to about so
Pl as a film or diffusion wall at a temperature of about 220°C to 350°C to 1% in the bom2-partial pressure region from about 80°C to about 450°C.
tantalum or niobium layered with /Cu- or, if possible, Pa/muf-, as a secondary melt with sodium- which is liquid at ambient temperature and must be free of impurities such as nitrogen and carbon. Use potassium alloy. Potassium hydride and sodium hydride are obtained as products in the form of a suspension.

This can be achieved by adding magnesium dissolved in the Mal at a proportion of oxygen that leads to corrosion phenomena of the membrane material, or a proportion of less than about 1 molar mass. Oxygen absorption can be carried out with lithium or with a melt containing lithium hydride. In this regard, it is known that even the oxygen dissolved in the metallic zirconium is eluted in this case.

Under the above conditions a large number of 10-6 mol H27CIL” a
A hydrogen flow density of .

2 about 500° to 450°C, especially about 1550°C in the hydrogen partial pressure region of the O gas mixture
At temperatures of 30°C, molten lithium is suitable as an acceptor for hydrogen and its isotopes. The membrane material is selected as in section 1. HTR - In order to separate hydrogen (H or T) from the primary circulating Il system, sufficiently pure isotope 7 Li must be used; a cost-effective configuration is described below in section 5.

5 Using an alloy of the above type of copper with Tψi/V and optionally niobium as the membrane material, on the gas side from 0.5 to about 20j111%% to about 1 to 5 OC (1
/pH-1 alloy is laminated. In the same pressure range as #12,
However, about 450℃ to 600℃, especially about SOO℃ to 550℃
A melt with a greater affinity for hydrogen and its isotopes (than lithium) at a temperature of °C is used on the secondary side. It is advantageous to use melts of alkaline earth metals in which calcium is dissolved. For example, it contains 66 atoms of cyparium, melts at 558°C as is known, and contains a large amount of calciparium. A mixture of barium and magnesium is used which is capable of dissolving the gum. Calcium-magnesium molten liquid (27 atoms per 1' in liquid form at 44!C) can also be used. Moreover, the three-substance system B&/Me/CI
ILs are advantageous in their affinity for hydrogen and its isotopes.

Of course, a tss term membrane containing lithium (in the field of conventional overuse of 4I) can be used as a hydrogen acceptor for about 10
It is possible to work at water bulk partial pressures below zero and at temperatures below about 600°C. Combinations of the membrane/melt rings of the embodiments described above are also possible, so that suitable choices can be made for each application case.

It is also possible to have a nine-diffusion membrane laminated with the palladium alloy according to the present invention, which has a nine-layer membrane structure with a nine-layer side oriented toward the outer wall and a secondary side with a sim material on the inner side. .

Of course, the separation of hydrogen (or its isotopes) from the melt also belongs to the practical example of items 1, 2 and 3. It is also known to separate the nonaqueous complex obtained in a cloudy state from an alkali metal melt or an alkaline earth metal melt by sieving.

Furthermore, it is possible to intensely heat the suspension and to thermally decompose the gaseous hydrogen and its isotopes thus formed.

Another feature of the known process is that the suspension - for example in the form of a column - is fed to the molten halide, whereby the hydride is eluted, and the hydride is taken up and the alkali metals and alkaline earth metals are removed. The point is to return the price to the remaining 90. This halide/hydride melt can be treated in a known manner with an electrolyte, whereby the alkali or alkaline earth metals are retained at the polycathode, while the hydrogen and its isotopes are retained in gaseous form at the anode. It can be obtained with

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the structure of a hydrogen-diffusion membrane according to the present invention, and FIG. 2 is a schematic diagram of the structure of another embodiment of the hydrogen-diffusion membrane according to the present invention. Symbols in the figure are 1...Padgelam-alloy layer 2.2'...Membrane material 5...Melt intermediate layer 4...Melt

Claims (1)

[Claims] 1. A method for separating hydrogen from a gas mixture by diffusion at high temperatures through a membrane laminated on the primary side with a palladium alloy, containing alkali metals and/or plucarious earth metals and The melt has a large affinity for hydrogen (the affinity of the primary wall material and the hydrogen-forming partner) and forms alkali hydrides and/or alkaline earth metal hydrides in suspension or in good shape. The above method in which mold is brought into contact with the membrane on the secondary side. 2. The process according to claim 1, wherein the ammonium is an alkali metal melt, in particular a MaK mixture or liquid lithium. & using as melt an alkaline earth metal or a mixture containing it and in particular a eutectic melt consisting of barium and magnesium, in which potassium is dissolved together in an amount of 30% O. - Method O described in paragraph 1. Table 9.Each elemental compound formed is simply separated from the melt, or the hydrogen is thermally decomposed to form a metal.
A method according to any one of claims 1 to 5. Claims 1 to 3 of the claims claim 1 to 3 above, in which the produced nine-element compound is produced especially by melt electrolysis and is separated as if dissolved in the nine-ha tetragenide Ss compound. Any one of the methods described in (h). 4. A hydrogen-diffusion membrane used in the method according to claim 1, comprising a palladium alloy layer on the hydrogen inflow side and made of a non-porous material that selectively permeates hydrogen. Or yttrium is an alloy partner
as ≧45 at% au or ≧50 atoms-mf or ≧7 atoms-! in the palladium alloy stack! of each alloy partner and that the membrane itself
The hydrogen-diffusion membrane described above has Cu, Mu, or Y in a concentration that is at least in equilibrium with the palladium alloy. 1. A hydrogen-diffusion membrane according to claim 6, wherein the membrane itself is saturated with copper, silver or yttrium and consists of nine substances. & the membrane itself consists of a tantalum- and/or niobium-based material.
Hydrogen-diffusion membrane as described in Section. The membrane itself is particularly saturated with copper and consists of an alloy of 910 to 50 wt. titanium, 3 to 10 wt. vanadium, 0 to 25 wt. niobium and at least 50 wt. tantalum. A hydrogen-diffusion membrane according to claim 8. :, 1 1α The membrane itself is saturated with steel and contains 20 to 25 wt. titanium, 5 to 7.5 wt. vanadium, 0 to 25 wt.
10. A hydrogen-diffusion membrane as claimed in claim 9, consisting of an alloy of 100% by weight niobium and at least 450% by weight tantalum. 1t The membrane itself has a nine-layer structure with an internal intermediate layer in the form of a melt forming or containing alkali metal hydrides and/or alkaline earth metal hydrides. 10. The hydrogen-diffusion membrane according to any one of items 1 to 10. 12. Hydrogen-diffusion membrane according to claim 1, wherein the intermediate layer is formed by a melt containing lithium hydride together with its halide in the form of a eutectic mixture. 15. A palladium steel alloy layer, a palladium silver alloy layer, or a palladium yttrium alloy layer is additionally provided on the hydrogen outflow side. 9. Claims 61.4 to 41
The hydrogen-diffusion membrane according to any one of items 3-1. ′(