DE1210425B - Process for the electrolytic production of phosphine - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

COIb

German class: 12 i - 25/06

Number: 1210 425

File number: H 51938IV a / 12 i

Filing date: March 4, 1964

Opening day: February 10, 1966

The subject of the main patent 1112 722 is a Process for the electrolytic production of phosphine from white phosphorus, which is characterized is that you pass an electric current between an anode and a cathode through an aqueous Electrolyte conducts, with the cathode made of one or more metals, which provide an overvoltage for hydrogen have, exists and periodically or continuously in contact with white phosphorus is brought, which is located in the aqueous electrolyte. The cells used for electrolysis are separated by a diaphragm into a cathode compartment and an anode compartment.

It has been found that the white phosphorus is not completely consumed during the electrolysis and becomes viscous after a while. When this occurs, then the phosphorus is supplemented or replaced as the viscous one Phosphorus reduces the efficiency of the cell and decreases the phosphine yield. According to the invention these disadvantages are avoided, the phosphorus is better used and the phosphine yield elevated. The invention thus relates to a method for the electrolytic production of phosphine from white Phosphorus in an electrolytic cell, which has a cathode, an anode, a diaphragm, an aqueous electrolyte and in the cathode compartment contains white molten phosphorus in contact with the cathode, wherein the cathode consists of a metal or a metal alloy on which hydrogen is an overvoltage possesses, according to patent 1112 722, characterized in that during the electrolysis by gases reducing the molten phosphorus in the cathode compartment, such as hydrogen, phosphine, hydrogen sulfide, Carbon dioxide, hydrogen cyanide, a saturated or unsaturated hydrocarbon or Mixtures thereof are passed.

When reducing gases are passed through the molten phosphorus, the phosphorus rises more easily on and remains in contact with the cathode, so that on the surface of the cathode a thin layer of phosphorus is held. In addition, it was found that the required current density in the cell is increased, thereby reducing the electrical power consumption and thus a high phosphine yield is permitted.

An embodiment of the cell used in the method according to the invention is shown in the drawing nahi explained.

F i g. 1 shows a central vertical sectional view the cell along 1-1; F i g. Fig. 2 is a horizontal sectional view taken at 2-2.

In the following, reference is made to FIG. 1 referred to.

Electrolytic manufacturing process
of phosphine

Addendum to the patent: 1112 722

Applicant:

Albright and Wilson (Mfg.) Ltd.,
Oldbury, Birmingham (Great Britain);
The Hooker Chemical Corporation,
Niagara FaUs, NY (V. St. A.)

Representative:

Dr. rer. nat. V. Vossius, patent attorney,

Munich 27, Pienzenauer Str. 92

Named as inventor:

George T. Miller, Lewiston, N.Y. (V. St. A.)

Claimed priority:

V. St. v. America March 4, 1963 (262 496) - -

The cell vessel 10 has an anode space 12, an anode 14, a cathode space 16 and a cathode 18. A porous diaphragm 20 separates the anode compartment from the cathode compartment and divides the electrolyte into the anolyte 7 and catholyte 19. White liquid phosphorus 24 is located in the cathode compartment 16. The diaphragm 20 is on its side facing the liquid phosphorus, where it is in contact with the phosphorus could occur, provided with a coating 22 so that it does not wet the diaphragm, which is shown by the convex meniscus 21. Openings 26 and 28 permit the continuous or intermittent addition and removal of anolyte from the anode compartment 12 and openings 30 and 32 permit the continuous or intermittent addition and removal of catholyte from the cathode compartment 16. The opening 34 permits the addition or removal of the Phosphorus. A sufficient amount of white phosphorus 24 is placed in the cathode compartment 16 to rest the lower part of the cathode 18 so that white phosphorus wicks a greater part of the surface of the cathode. It is an anolyte gas discharge

609 507/310

3 4

RungsöfTnung 36 on the upper part of the anode compartment 12 advantages in the production of phosphine. It results

for the removal of anolyte gas and a catholyte gas itself an increased current density at the cathode, the zui

discharge opening 38 in the upper part of the cathode- producing phosphine used in the cell

Raumeslö for the removal of catholyte gas pre-phosphorus, can, for a longer period of time, within the cell

seen. Gas-liquid interfaces are to be kept at 15 5, which means more phosphine per unit

designated. The line 60 carries the outflowing phosphorus introduced into the cell, and

Catholyte gas to the gas-liquid separator62, the phosphorus is due to the formation of phosphorus

which a cooler, a centrifuge or another phosphor droplet as a film, which is attached to the cathode

suitable apparatus. Here the gas surface adheres more easily and rises, in effective

and the liquid electrolyte, which was carried with it, brought more full contact with the cathode,

can be separated from each other. The liquid phase The viscosity of white phosphorus is at

is the electrolyte 19 in the cell through the 50 ⁰ C for about 1.55 cP. When the viscosity of phosphorus

Line 61 returned. The line 64 carries that in the cell is about 8 to 9 cP at 50 ° C, then it is

Catholyte gas to cooler 66 where some electrolyte degrades cell performance to such a degree

which has passed into the gas phase, condenses 15 that the phosphorus for the purpose of an effective

and can be returned to cell 10. The operation is to be supplemented. It was determined,

non-condensed gases, mainly phosphine, that by blowing, flushing, stirring or agitation,

are then circulated through the line 68 to the pump 70, bubbling or reducing the phosphor

and / or delivered to a storage container. In the phorschmelzbades with a reducing gas the

generally only a small portion of the catholyte viscosity will generally be between about 1.6 and

gases branched off through line 68, which is kept above the 4.5 cP. Very favorable results will be

Line 72 obtained by means of the pump 70 through the opening when the viscosity is reduced by a

73 recirculated into phosphorus 24 at 74- gas is maintained between about 1.55 and 7 cP, with

to be led. . all values refer to measurements at 50 ° C in one

The electrolysis current is supplied to the electrodes through 25 viscometers of the Ostwalk-Fenshi type,

the conductors 40 and 42, which are the anode and the diaphragm 20, which the anode space 12

Cathode with the positive or negative pole separating one from the cathode compartment 16 can be a porous or

Connect DC power source 44. be semipermeable material, which compared to the

If necessary, heating or cooling devices can be used. Cell content is resistant and the anolyte and genes like a constant temperature bath (not keeping catholyte gases separate, but passing through drawn), used to put the cell on or the electrolyte. Typical examples of as Materials suitable for diaphragm formation in the vicinity of the desired operating temperature are porous aluminum. 'dum or porous artificial corundum, porous

The cell jar 10 can be made of any material, porcelain, wool felt impregnated with synthetic resin and which is resistant to corrosion by the electrolyte and various other partitions such as those in lead, other materials used in the cell, accumulators normally used,
be made. Typical examples of suitable The cathode consists of a metal or a material are glass, glazed ceramic materia- metal alloy, other hydrogen an overvoltage lien, tantalum, titanium, hard rubber, polyethylene or with, z. B. of lead, amalgamated lead, cadmium, phenol-formaldehyde resin coated solid or rigid 40 tin, aluminum, nickel, nickel alloys, such as a material. Alloy with 77.2% nickel, 4.8% copper, 1.5% ■ Usable reducing gases include water-chromium and 14.9% iron, monel metal, copper, phosphine, hydrogen sulfide, carbon oxide, silver, bismuth and their alloys. Hydrogen cyanide, saturated and unsaturated gas, lead-tin, lead-bismuth and tin-bismuth hydrocarbons such as ethane, methane, 45 alloys can be used. Different butane, butene, acetylene and other natural burning forms of cathodes can be used, gases and mixtures thereof. The gases may be from, for example, the cathode may be a plate or an external or internal source through conduit 72 may be rod as shown in the drawings. are released, rinse the phosphorus and, if necessary, mats of metal wool can also flow off the opening 38. It is preferable to use 50 and porous metal plates. Some of the catholyte gases can be returned to the circuit so that a mercury cathode can also be used.
to flush the phosphorus. The speed with. Suitable anode material is e.g. B. lead, platinum, which these gases are given off to the phosphorus, lead peroxide or graphite.

can be from about 5.38 to 10761 / hr. per square meter You can use a lead plate with grooves or notches

Vary cathode area. About 5.38 55 th are preferred as the cathode and a graphite plate as the anode

up to 269 l / h / m ^a . The best results will be when using. It was found that among these

Use about 10.76 to 215.21 / hour. the wicking effect of the lead cathode per conditions

Square meters of cathode area achieved. The proportion of is significantly improved.

Catholyte gas, which is returned in the circuit. Any aqueous electrolyte can be used, from about 10 to 90% of that at cathode 60 may not react with the molten phosphorus total gas generated vary. The preferred amount of water under the conditions of the electrolysis, which is returned in the cycle, forms substance or hydrogen ions. This includes the is about 60 to 75% of the total catholyte gas. aqueous solutions of hydrochloric acid, sodium chloride, Optimal results are obtained when about 25 lithium chloride, potassium chloride, sodium sulfate, kaiibis 35% of the catholyte gas recirculated 65 umsulphate, monosodium phosphate, sodium phosphate, will. Rinsing the phosphorus with a reduced- acetic acid, ammonium hydroxide, or phosphoric acid generating gas, preferably by recycling the sulfuric acid and mixtures thereof. The concentrated catholyte gases in the circuit, leads to manifold tration of the compound in the aqueous electrolyte

vary from about 1 to 95%, but is generally about 5 to 80%; about 10 to are preferred 50%.

It has been found that the yield of phosphine can be improved if it is in the electrolyte certain metal ions, such as antimony, bismuth, lead, tin, cadmium, mercury, silver, zinc, cobalt, Calcium and barium, in small amounts. The concentration of metal ions is between 0.01 and 5 percent by weight, based on the electrolyte. The metal ions can by using a consumable anode of the desired metal or metals, such as a lead anode, in the Electrolytes are introduced, whereby metal ions are formed in the anolyte and transferred into the cathode compartment will. It can also use salts or other compounds of metals, such as chlorides, phosphates or acetates, are dissolved in the electrolyte. In another embodiment, finely divided metal is used added to the electrolyte.

During the electrolysis, the temperature of the electrolyte should be above the melting point of phosphorus (about 44 ° C) and below the boiling point of the electrolyte. Tm general will be obtained satisfactory results at temperatures of about 60 to 110 ° C; optimal phosphine yields are achieved at temperatures of around 70 to 100 ° C. When you get through the cell Electric current passes through it, is on the surface of the cathode due to the formation of the catholyte gas in the cathode compartment, molten phosphorus consumed. The catholyte gas consists mainly of phosphine and contains small amounts of hydrogen. Some of this gas can be recycled and carried through the molten phosphorus in the cell be directed. The anolyte gas composition depends on the overvoltages of the anions in the anolyte in with respect to the anode material and the electrolyte. For example, oxygen is predominant in the anolyte gas, when using sulfuric acid or phosphoric acid with a platinum anode, while at When hydrochloric acid is used as the anolyte, chlorine predominates in the same anode.

The gas generated at the cathode has a relatively high phosphine content of generally more than 60%, which can even be 90 percent by volume or more. The catholyte gas is essentially free from other phosphorus hydrides.

The invention is illustrated by the following examples explained in more detail.

example 1

Cell very viscous (over 8 cP), and the analysis of the catholyte gas showed that it was only about 8% Contained phosphine.

b) Additional molten phosphorus (60 parts) was added to the cell at 50 ° C.

The operating conditions were with the exception that hydrogen gas through the liquid phosphorus was headed, kept the same. The electrolysis was operated for 7 consecutive days. the The composition of the catholyte gas was changed at intervals certainly. During this period the liquid phosphorus did not become viscous, and analyzes of the catholyte gas indicated that 70 to 75% phosphine was present in the catholyte gas.

Example 2

Phosphorus was introduced into the cell used in Example 1, and Example 1, b) was used with

ao repeats the difference that about 40% of the catholyte gas is used to flush the phosphorus in the circuit and no additional hydrogen was used. After 24 hours it was with the circulation of the catholyte gas is stopped and the cell continued to operate. The content of phosphine in the catholyte gas without the introduction of im Recycled catholyte gas into the cell was then released for a period of about one minute Hour determined. The results are shown in Table I below.

Table I.

35

40

45

Time in minutes Percent phosphine present 0 84 5 87 10 86.5 17th 85 22nd 83 38 79.5 55 69

50 After an hour, 50% of Katholytgases were about back again circulated. The results of subsequent analyzes are compiled in Table II.

Table II

a) Liquid white phosphorus (40 parts) was placed in an electrolyzer cell. The cell had a Lead cathode and a graphite anode. The electrolyte in the cell consisted of 10% hydrochloric acid with about 0.04% finely divided lead dissolved therein. The cell was covered with a fiberglass fabric Coated alundum diaphragm divided into an anode and cathode compartment.

After introducing the phosphor into the cell, direct current was passed through the cell at one potential led by 4 V. At the start of the electrolysis, the catholyte gas was analyzed for phosphine and it was found that it was 30 to 40% phosphine duration. After 7 days of continuous operation (approximately 326 ampere hours), the phosphorus in the

Time in minutes Percent phosphine present 8th
21 73
75.5

Example 3

The electrolysis was carried out according to Example 2, but the speed was with which catholyte gas was recycled varies. Each attempt was 24 hours carried out. The variation in the rate of circulation and the content of phosphine in the Catholyte gas are given in Table III below.

Table III

Speed of Average Circulation of the Phosphine content Catholyte gas of the catalyst gas, Q / hour / m ⁸ ) (%) 21.52 77 75.32 80 118.36 85 161.40 92 279.76 85 172.16 90

IO

Claims (3)

Patent claims: 1. A process for the electrolytic production of phosphine from white phosphorus in an electrolysis cell comprising a cathode, an anode, a slide ^zo phragma, an aqueous electrolyte in the cathode compartment and white melted phosphorus in contact with the cathode, the cathode made of a metal or a metal alloy exists, at which hydrogen has an overvoltage, according to patent 1112 722, d a duich characterized that during the electrolysis by the molten phosphorus' reducing gases in the cathode space, such as hydrogen, phosphine, hydrogen sulfide, carbon oxide, Hydrogen cyanide, a saturated or unsaturated hydrocarbon, or mixtures thereof, passed will. 2. The method according to claim 1, characterized in that developed from the cathode compartment Gas such an amount is returned to the cathode compartment and passed through the molten phosphorus that the Gas speed about 5.38 to 10761 / hour. per square meter of cathode area. 3. The method according to claim 2, characterized in that the gas speed is about 10.76 to 215.21 / hour. per square meter of cathode area 1 sheet of drawings 609 507/310 2.66 © Bundesdruckerei Berlin