JPS5993891A - Joined body of ion exchange membrane to electrode and its production - Google Patents

Abstract

PURPOSE:To provide a titled joined body as an anode for water electrolysis having a low oxygen overvoltage and excellent durability by sticking alloy particles consisting of three components, such as Ni or Co, Al, etc. and a noble metal, etc. having a prescribed compsn., as an anode, on an ion exchange membrane. CONSTITUTION:The alloy particles having the prescribed compsn. consisting of the three components X, Y, Z; the component X=Ni and/or Co, the component Y=Al, Zn, Mg, or Si, and the component Z= a noble metal or Re, are stuck on an ion exchange membrane and is thereafter treated with an aq. caustic alkali soln., whereby at least a part of the metal of the above-mentioned component Y is eluted off and the above-mentioned alloy particles are made porous. A joined body of an ion exchange membrane to an electrode wherein the particles of the electrode active metal consisting of the alloy having the compsn. of the above- mentioned three components X, Y, Z in the range enclosed with the points A, B, C and D, more preferably in the range enclosed with the posints A, B, E and F in the compsn. diagram are deposited, as an anode, to an ion exchange membrane is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an anode for water electric study, and more particularly to an electrode catalyst ion membrane assembly capable of water electrolysis at low voltage and a method for manufacturing the same.

Reflecting the recent energy situation, hydrogen is attracting attention from many quarters as a new energy source to replace oil. Industrial hydrogen production methods can be roughly divided into water electrolysis methods and coke or petroleum gasification methods. Although the former method uses water, which is easily available as a raw material, it requires a large number of electrolytic equipment, is insufficiently adaptable to excess or insufficient current, and has problems with electricity b due to limited return of the liquid. - Many problems remain in terms of deterioration, floor space, equipment costs, etc., and the main purpose of the present invention is to vaguely bond cation exchange using such a cation exchange membrane.

Generally, base metal (nickel), nickel porous bodies, nickel composite oxides, etc. are used as base metal (base metal)-based electrode catalysts. Compared to the previously known electrodes, this electrode has a greater effect in terms of lower oxygen overvoltage and its durability.However, as a result of more detailed inspection, the inventors discovered that the above-mentioned electrode also exists. We have found that in some cases, durability is not always sufficient.
As a result of diligent efforts to resolve this issue, we have discovered the present invention.

Furthermore, the present invention is advantageous in the so-called SPB water electrolysis, in which water electrolysis is performed at a lower voltage than conventional electrodes, and an anode is already preferably used, but it has been found that the above-mentioned electrolytic operation causes an increase in the severe overvoltage.

As a result of deep investigation into this phenomenon, the present inventors found that the electrode activity deteriorates due to the nickel or cobalt in the Raney nickel particles or Raney cobalt particles, which are electrode active ingredients, deteriorating into nickel hydroxide or cobalt hydroxide (i.e., due to the deterioration of the electrode activity). It was discovered that overvoltage increases), and nickel is used to prevent this deterioration.

The first ingredients such as cobalt and aluminum, zinc.

A third 4J to known metal particles consisting of a second component such as magnesium or silicon! The present invention was completed based on the discovery that the inclusion of a component selected from i-metal and rhenium brings about a remarkable effect and also has a remarkable effect of reducing oxygen overvoltage. The range Y1 where 2 is quadrupled at points A, B, C, and D in Figure 1 and the component 2 selected from rhenium is the second
Crystal plane 1 characterized in that electrode active local particles made of an alloy in the quadruple range of points 4', B', C' and D' in the figure are applied to an ion exchange membrane as an anode. Kusu tii Ion-supplying membrane conjugate! The main idea is the I method.

Here, the precious metals include gold, silver, and platinum metals (i.e., platinum, rhodium, ruthenium, palladium,
iridium)? It means something.

Here, FIG. 1 is a ternary component diagram of component x1 consisting of nickel and/or hakohardt, component Y selected from aluminum, zinc, magnesium, and silicon, and component 2 selected from noble metals and rhenium, which is the electrode catalyst of the present invention. The active alloy composition is surrounded by points A, B, O and D in Figure 1 (79,6,20,0,4) and E (60,20°20
), F(80,0,20).

The effects of the present invention are due to the inclusion of a component selected from nickel metals and rhenium as one component of the alloy composition, but it is believed that the inclusion of these components prevents the formation of hydroxides of nickel or cobalt. The details of whether this is possible have not yet been clarified. However, the present inventors have found that among these components, platinum, rhodium, and ruthenium are most suitable for achieving the effects of the present invention. That is, when using platinum, rhodium, and ruthenium among metals, the present electrocatalyst ion exchange membrane assembly can maintain an especially low oxygen overvoltage for a long period of time even under severe environmental conditions.

It is preferable that the alloy of the anode of the bonded body of the present invention has a composition surrounded by ABCD in FIG. The diameter is also related to the porosity of the electrode surface and the dispersibility of particles during electrode manufacture, which will be described later, but a diameter of 01 μm to 100 μm is sufficient.

In the above range, from the viewpoint of porosity of the electrode surface, preferably 0.1 to 50 μ, more preferably 0, jp-j O
μ.

Furthermore, the layer of the alloy of the present invention is preferably superficially porous in order to achieve a lower oxygen overpotential than the electrode. Furthermore, it is preferable that the inside of the particles be porous.

As for the degree of porosity, it is preferable that the degree is quite large, but if the degree of porosity is excessively large, the mechanical strength of the particles decreases, so it is preferable that the porosity is 20% to 90%. Preferably in the middle of the above range, 35 to 8
5%, particularly preferably 50-80%.

The porosity mentioned above is preferably determined by the known nitrogen adsorption method to obtain water flame porosity.

In such a case, a method 6' is preferred in which an alloy in which components X, Y, and Z are uniformly blended in predetermined proportions is treated with caustic alkali to remove at least a portion of the metal of component Y. In the case of the anode of the present invention, when producing hydrogen by water electrolysis of an alkaline aqueous solution, it is not necessarily necessary to treat it with caustic alkali before installing it in the electrolysis tank, and the anolyte used is under caustic conditions. Therefore, during electrolysis, the content of component Y is gradually removed and becomes the desired anode.

In the case of the present invention, the metal particles include component X consisting of nickel and/or cobalt, aluminum, zinc,
Component Y selected from magnesium and silicon and component 2 selected from noble metals rhenium are at point A' in Figure 2,
It is necessary that the alloy be in the 91β range surrounded by E', O' and D'.

In addition, A', B', O', in Fig. 2
Alloy D'40.0.2), B'(39,8,60,0
,2), C'(s, 6o, 35), D'(12,4
0.48).

The reason for this is that, outside this range, the activity of the alkaline earth metal, that is, component Y, as a catalyst for dissolving tl' and later elec- tric acid and r1 is insufficient.

Or 1. This is because even if the amount of precious metal components exceeds that of Kihanshi and Aishima, the oxygen overvoltage reduction effect and durability will not be significantly improved.

Various combinations of compositions of the metal particles can be used, and typical examples include N1-AI-Pt
, Ni-Al-Rh, Nj, -Al-Ru
, N1-Zn-J't.

Ni-Zn-Rh, Ni-Zn-Ru, N
i-1Ei-Pt, Ni-8i-Rh.

Ni-5i-Ru, Co-Al-Pt, C
o-Al-Rh, co-AI-, Ru.

Co-Zn-Pt, co-Zn-Rh, C
o-ZIl-Rlx, Co-8i-Pt.

Ni-Mg-Ru, Co-Mg-Pt, C
! Possible examples include o-Mg-Rh and Co-Mg-Ru.

Among these, a particularly preferable combination is not particularly limited to Ni-Al-; In the case of an alloy with a composition as described below, 10% by weight of caustic alkali (NaOH equivalent) of 10 to 35% by weight.
It is preferable to immerse it in an aqueous solution at ~100°C for 0.5 to 30 hours. For this reason, component Y was selected on the condition that it should be as easy to remove as possible.

Moreover, component 2 is not removed by the above-mentioned alkali treatment.

The thus obtained electrode ion membrane assembly is then treated with caustic alkali (for example, immersed in an aqueous caustic solution) as necessary to elute and remove at least a portion of the metal of component Y in the alloy particles. particle? Make it porous.

The conditions in such a case are as stated above.

In addition, when using an alloy of components X, Y, and Z as described above, it is preferable to perform the caustic alkali treatment as described above, but when such an alloy is used, the metal of component Y may be removed during the electrolysis process. There is no problem with melting.

In the case of the present invention, the electrode catalyst used as the cathode is not particularly limited, and may be any of various noble metals that are effective as cathode catalysts, such as ruthenium, rhodium, iridium, and platinum. Furthermore, a nickel-based electron catalyst may also be used. These may be directly bonded to the membrane, and may be bonded to a separate core using a method such as dipping, chemical plating, or bonding.
A ζ electrode body bonded by plating, spraying, or the like may also be used. It goes without saying that in this water electrolysis method, it is preferable that the hydrogen overvoltage is as low as possible. Further, as the cation exchange membrane used in the present invention, any known fluorine-containing cation exchange membrane may be used, but in particular, a perfluorinated carbon membrane having a carboxylic acid group as an imen exchange group (for example, Showa 51-140 -899
Examples 1 to 12 disclosed in JP-A No. 52-48598 were added and kneaded for 15 minutes to obtain catalyst 4 paste. C
F2= CF2 and 0F2-OFO(CF2)3COOO
Copolymer with H3 has an ion exchange capacity of 1.9 meq/
Each of the above alloy powders was coated on one side of a cation exchange membrane made of F resin and having a film thickness of 150 μm using a 1.0 μ/c!n2 screen printer.

On the other side of the ion membrane, 3 pieces of ruthenium black prepared separately were placed.
17cm2 was applied. Next, heat this at 150℃ and 250℃.
Pressed at F47cm2 for 10 minutes. 80℃, 15%
Hydrolysis was carried out with an aqueous KOH solution for 20 hours.

Here, a part of the electrode catalyst was peeled off and the composition was analyzed.

Next, using N1 as a current collector and using the ruthenium black side as a cathode, 15-fiber KOH 1110°C, 100
Electrolysis was performed for 60 days under A/dm2 conditions.

The initial oxygen overvoltage of each electrode catalyst, the oxygen overvoltage after 30 days, and the electrode after hydrolysis of the ionic membrane were evaluated. Table 2 shows the changes in oxygen overpotential.

Comparative Examples 6 to 6 Electrocatalyst-ion membrane assemblies were produced in the same manner as in Examples except that the composition of the alloy powder was changed to those shown in Comparative Examples 3 to 6 in Table 2. Table 2 shows the test results conducted in the same manner as in the examples.

Comparative Examples 6 to 4 show that even if the Rh and Ir alloys are increased beyond a certain level, no particular improvement in performance is observed.
Comparative Examples 5 and 6 show that the composition of the raw material powder is outside the appropriate range, so the oxygen overvoltage is higher than the initial value.

Table 2

[Brief explanation of the drawing]

In Figure 1, X = Ni or Co, Y = Al
, Zn. The composition in the range surrounded by points A, B, O, and D in the diagram consisting of the three components Mg or Sl, 2=noble metal or rhenium indicates the activity of the electrocatalyst-ion exchange 1iC+ of the present invention [↓
The composition of the alloy of the electrode particles is shown below. Figure 2 shows that X = Ni or Co, Y = AI
, Zn.

Claims (1)

[Claims] (1) An alloy consisting of a component X consisting of nickel and/or cobalt, a component Y selected from aluminum, zinc, magnesium, silicon, and a component 2 selected from a noble metal, rhenium, on an ion exchange membrane, where the components X, Y ,
Z is X in Figure 1, component Y selected from aluminum, zinc, magnesium, and silicon, and component 2 selected from noble metals and rhenium are points A' and B' in Figure 2. A method for producing an ion exchange membrane and an electrode assembly, characterized in that electrode active metal particles made of an alloy in the range surrounded by D' and D' are attached to an ion exchange membrane as an anode.