US1148194A - Process for the manufacture of alkali amid. - Google Patents

Description

B. R. SEIFERT & W. LEIBROCK. I PROCESS FOR THE MANUFACTURE OF ALKALI AMID- APPLICATION FILED DEC. 5. I9!!- Patented July 27, 1915.

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I BRUNO RICHARD SEIIFERT, 0]? RADEBEUL, NEAR DBESDEN, AND WILHELM LEIBRO GK,

0F DRESDEN, GERMANY, ASSIG-NORS T0 CHEMISCHE FABRIK VON HEYDEN, AKTIEN- GESEILLSCHAFT, 0F RAIDEIBEUL, NEAR DRESDEN, GERMANY.

PROCESS FOR THE MANUFACTURE OF ALKALI AMID.

Application filed December 5, 1911. Serial No. 664,113.

To all whom it may concern:

Be it known that we, BRUNO RICHARD SEIFERT, chemist, a subject ,of the King of Saxony, and resident of Albertstrasse 6b,-

Radebeul, near Dresden, Kingdom of Saxony, German Empire, and WILHZELM Lemnoox, engineer, a subject of the King of Bavaria, and resident of Grosse Zwingerstrasse 13, Dresden, Kingdom of Saxony, German Empire, have invented a new and useful Process for the Manufacture of AlkaliAmid,

the surface of a layer of molten sodium, or

according to the process proposed b Ewan and Pfleger (U. S. Patent No. 6 4,295), according to which the ammoniacal gas is conducted not over but below the surface of the molten sodium and is allowed to bubble up in a rapid current through the stance, lead sodium alloy. From the fact,

however, that up to this day, the sodium amid is manufactured on the largest scale not from the'cheap lead sodium alloy but exclusively from sodium itself, it may be concluded that serious difliculties prevent the use of the lead sodium in the manufacture of amid. Various experiments have shown that such difficulties really exist. If,

for instance, the ammonia is directed below the surface of molten lead sodlum instead of molten sodium and is allowed to bubble up rapidly through the lead sodium, the re- Specification of Letters Patent.

. point.

4 Patented July 2'3, 1915.

action will take place very slowly, so that the production of a certain quantity of amid from lead sodium requires a multiple of the time necessary for the manufacture of the same quantity of amid from pure sodium under the same conditions. A considerable portion of the ammonia escapes without reacting with the alloy and it is even necessary to apply additional heat.

The rapidity with which the reaction takes place between the alkali metal alloy, for instance lead-sodium, and ammonia, depends upon the quantity of sodium within the alloy, the smaller the quantity of sodium, the slower the reaction. However, the alkali metal alloys of a lower percentage represent the form in which the alkali metal can be produced in a much cheaper and more simple manner than in the form of the pure alkali metal.

The melting point of lead sodium of a low sodium percentage, viz: containing up to about 6 per cent. of sodium, is below the melting point of lead, that is, below 327 degrees centigrade. The melting point of lead sodium containing more than 6 per cent. sodium is much higher; so for instance lead sodium containing 10 per cent. of sodium melts at 365 degrees centigrade and lead sodium containing 19.5 per cent. of sodium melts even at 420 degrees centigrade. Ifammonia is to be introduced below the surface of molten lead sodium for the production of sodium amid according to the process of Ewan and Pfleger, this must be done at a temperature substantially above the melting point of the alloy, the supply pipes for the gas being obstructed and the procedure disturbed, if the ammonia is introduced at a temperature near the melting It is known that the temperature most favorable for the manufacture of sodium amid from pure sodium is at 340 to 380 degrees centigrade. Therefore it will be suitable for the purpose to use a lead sodium alloy melting at an essentially lower temperature, viz: lead sodium having a low percentage for instance a lead sodium containing 8 per cent. of sodium.

As already stated above, the introduction of ammoniacal gas below the surface of such molten lead sodium is not well suited for the production of sodium amid. Also in the process proposed by Castner the substitution of the sodium by the cheaper lead sodium will not give a good result, because the specific gravity of the amid is less than that of the lead sodium; the amid will therefore cover the surface of the alloy and interfere with the continued reaction of the ammonia, whereas, if sodium is used in the Castner process, the amid will sink below the molten sodium, because the gravity of sodium amid is greater than that of pure sodium, and the surface of the sodium remains constantly exposed to the action of the ammonia.

Now it has been stated that sodium amid can be obtained in a remarkably cheap and technically simple manner in treating such alkali metal alloys as can be easily manufactured by electrolysis and having a small percentage of sodium, for instance a lead sodium of '6 to 8 per cent, in a finely divided state with ammonia at temperatures near 400 degrees centigrade, that is, below the decomposition temperature of alkali amid. By dividing the alkali alloy into fine particles, the reaction is unexpectedly accelerated so that a complete absorption of the ammoniacal gas is effected most readily and completely. The ammonia may be applied with or Without pressure. In the case last mentioned the reaction is still somewhat accelerated. However, it is neither necessary nor, in most cases, advantageous to work under pressure, as the apparatus will be of a more complicated arrangement, if an excess of pressure is used.

The drawing annexed to the description shows by way of example, one of the various forms of apparatus which may be used.

1 indicates kettle of steel that may be heated from outside. I

2 is an iron cover provided with an inlet plpe 3, an outlet pipe 4 and a stufling box 5, for a shaft 6. The shaft can be driven with high speed by thebelt 7 and at its bottom end a round plate or disk 8 is fastened which may be quite flat or perhaps formed somewhat conical as a fiat funnel shown in the drawing. The kettle may also be fitted up with pipes 9, 10 and 11 for the inlet and outlet of molten lead sodium alloy, and for the outlet of the amid formed. The molten alloy entering the kettle through pipe 9 is flowing onto the rapidly rotating plate 8, so that the alloy will be divided into fine particles and sprayed against the wall of the receptacle. The ammonia introduced by pipe 3 will be almost immediately consumed and the hydrogen formed will escape through pipe 4:. It may be allowed to burn in the air or may be gathered for other purposes. The consumed lead sodium alloy 12 is gathered on the bottom of the kettle and may be allowed to leave it by the overflow pipe 10. It can be reconducted to the electrolytic cell in order to be enriched again with sodium. The amid formed, 13, is allowed to leave the kettle by the overflow 'pipe 11 and may be used for any purpose,

for instance, for the manufacture of cyanamid or cyanid.

The apparatus for performing the process described may be greatly modified.

The reaction between ammonia and the finely divided alkali metal alloys is such a rapid one that it is not necessary to make use of apparatus, based on the counter-current principle for the purpose of insurin a totalconsumption of the ammonia use However, the reaction may be performed also in apparatus working according to the counter-current principle, viz: generally in allapparatus for the rectification of liquids. In apparatus constructed like known rectification apparatus, the alkali metal alloy is conducted as a molten liquid in countercurrent against a gaseous stream, consisting of pure ammonia at the inlet and of pure hydrogen at the outlet.

The new process described allows the manufacture of alkali amid from the alkali metal alloys in a most economical and simple manner, alkali metal alloys being obtainable much easier than pure alkali metals. The new process involves an important technical progress in'the manufacture of alkali amid.

What we claim is:

1. Process for the manufacture of alkali amid from alkali metal alloy and ammonia which consists in exposing the molten alkali metal alloy in finely divided state to the action of ammonia.

2. Process for the manufacture of alkali amid from alkali metal alloy and ammonia which consists in exposing the molten alkali metal alloy in finely divided state to the action of ammonia, the fine division of the molten alkali metal alloy being effected by centrifugal power action.

3. Process for the manufacture of alkali amid from alkali metal alloy and ammonia which consists in exposing the molten alkali metal alloy in finely divided state to the action of ammonia, the ammonia being employed under an elevated pressure.

4. Process for the manufacture of alkali amid from alkali metal alloy and ammonia as our invention, we have signed our names which consists in exposin the molten alkali in presence of two Witnesses, this twentieth 10 metal alloy in finely divi ed state to the acday of. November, 1911.

tion of ammonia, the fine division of the BRUNO RICHARD SEIFERT. molten alkali metal alloy being efiected by WILHELM LEIBROOK. centrifugal power action and the ammonia Witnesses: 7

being employed under an elevated pressure. PAUL AREAS,

In testimony, that we claim the foregoing CLARE SIMON.

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