A Process for the Economic Production of Cyanides, their Derivatives, and other Nitrogen Compounds.
Year: 1897

page_text: Date of Application (in the United Kingdom), 11th Nov., 1897
Complete Specification Left, 11th Nov., 1897--Accepted, 2nd July, 1898
COMPLETE SPECIFICATION.
A Process for the Economic Production of Cyanides, their
Derivatives, and other Nitrogen Compounds.
We, DENIS LANCE (Doctor of Sciences), of 131, Avenue de Villiers, Paris, France,
and RAPHAEL LOUIS EMMANUEL DE BOURGADE (Doctor of Sciences), of 48, Avenue de
Ceinture, Enghien-les-Bains (Seine et Oise), France, do hereby declare the nature
of this invention and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :-
This invention relates to a process for the economic production of cyanides, their
derivatives and other nitrogen compounds by fixing the nitrogen by the simultaneous
action of hydrogen, nitrogen, and ammonia upon carbon. By hydrogen is to be
understood not only the pure gas but all the carbides of hydrogen, water gas, and other
hydrogen compounds. Similarly the nitrogen may be employed in the form of
mixtures more or less rich in this gas such as atmospheric air, the products of
combustion from furnaces, etc.
It is known that by the reaction in presence of a source of intense heat (electric
or other) of a mixture of acetylene (CH2) and nitrogen, hydrocyanic acid
(CNH) is formed in quantityap proaching more nearly to the theoretical amount,
the greater the quantity of hydrogen present, the maximum being obtained when
the volume of hydrogen is equal to at least 2 times that of the hydrogen in
combination in the acetylene.
=
Our process which has for its basis a similar reaction, consists in passing a mixture
of nitrogen, hydrogen, and aminonia over carbon thereby forming an acetylenic
carbide of ammonium C(NH4)2: C'Am² (acetylenide of ammonium)-analogous
to (CH2) acetylene (CK2) acetylenide of potassium-a transitory compound in
which the free nitrogen becomes fixed forming cyanide of ammonium (C2N, NH³).
As in the previous case the yield in cyanide of ammonium (C2N, NH4) more
nearly attains the theoretical yield indicated by the two concomitant equations
following :-
=
=
2 (C2N, NH) as the mixtures of the
2NH3+2H+4C C^(NH)².C(NH)²+2N
three gases N, H, NH³ (nitrogen, hydrogen, and ammonia) is accompanied by a volume
of hydrogen so calculated as to be in the same ratio as before mentioned to the initial
volume of the term which corresponds to the hydrogen of the acetylene in the
acetylenide of ammonium under consideration.
The cyanide on being decomposed either by means of a weak acid or by dilute

page_text: solutions of strong acids, or by a base more fixed than ammonia, disengages in the
two first cases its anhydrous hydrocyanic acid (CNH) and in the latter case its
ammonia (NH³).
The process thus consists in the action upon carbon, of a mixture of nitrogen,
hydrogen, and ammonia at a high temperature produced by electrical or other means
which temperature is not rigidly fixed but is a function of the velocity of the passage
of the gases over the carbon.
The following details will suffice to shew the manner in which the heating
temperature is regulated in different cases. We take an internally glazed porcelain
tube of a diameter of, say 0-03 m. containing a column of carbon of, say 0·20 m. in 1
height, which is heated to the temperature of the reaction. The temperature taken
externally and tangentially to the tube should indicate 1100° to 1150° corresponding
theto an average internal temperature of from 1000° to 1100°. Under these conditions the
pressure in the interior of the tube being from three to four centimetres of mercury,
the rate of flow of the complete mixture should be eighty litres per hour, to obtain a 1
maximum fixation. It follows from the above data that the rate of flow should
increase or diminish according as the temperature of the tube is increased or reduced,
or the duration of the heating should be extended, if the same temperature is
employed.
The retorts and other apparatus should be constructed of substances which do not 2
cause the decomposition of cyanogen or cyanides such as glazed porcelain for example.
The gaseous mixtures should correspond to the following indications :-It is necessary
when employing the general process which consists in causing free nitrogen to act on
a base in presence of carbon, that the metal of the base (✗) should form with the
carbon a transitory combination of the form C*X2 in which the free nitrogen becomes 2
fixed. For this purpose it is necessary to add to the ammonia gas employed, a
sufficient quantity of hydrogen to form the combination C+ (NH4)2 corresponding to
C4X2 above mentioned. Moreover, as it is compulsory, in order to obtain the
compound C(NH4)2 to operate at a temperature at which the separation of the
aminonia takes place under ordinary conditions, it becomes necessary in order to avoid
this separation to add to the preceding mixture a volume of hydrogen equal to at
least from two-and-a-half times to three times the volume of the initial components of
the expression NH' in the compound C(NH4)2 previously referred to.
For practical working on an industrial scale it is advisable to employ the following
mixture which gives the same results as the pure mixture of ammonia gas, hydrogen,
and nitrogen. Instead of pure hydrogen we may employ a mixture of various hydro-
carbons which may be readily obtained by the distillation of organic substances. The
nitrogen is itself drawn from atmospheric air by any of the known processes.
The following proportions give good results in practice :-
80 litres of ammonia gas;
2000 litres of hydrocarbons obtained as before ;
200 litres of nitrogen of the air.
This mixture on being passed over carbon in the manner hereinbefore specified,
yields cyanide of aminonium.
4
To obtain cyanide of potassium, it is only necessary to decompose the cyanide of 4

page_text: meters before the gases enter the mixer. The gases after being intimately mixed
are passed over heated carbon and on leaving these apparatus the gases pass into
alcohol-absorption apparatus where they bubble through the liquid or are absorbed
by surface contact. On leaving there remains a mixture of hydrocarbons, hydrogen,
nitrogen, and ammonia. The three first gases pass to a gas holder where a mixture
is reconstituted in suitable proportions for use over again. The ammonia gas is
obtained in aqueous solution and conducted to the retort.
If it is desired to make ferro-cyanides, an aqueous solution of potash heated to 100°
and stirred with iron turnings or old scrap iron is used in the apparatus for making
cyanide of potassium.
We therefore claim as our invention the general process of preparing cyanides and
hence of all compounds such as ferro- and ferri-cyanides, Prussian blue, Turnbull
blue, etc., etc., by the fixation of nitrogen by the simultaneous action upon carbon of
nitrogen, hydrogen, and aminonia in definite proportions whether :-
be employed. Or whether cyanide of ammoniumn be directly utilized or its base be
replaced by any other base, or whether ammonia and hydrocyanic acid be separately
employed.
a
By direct utilization of cyanide of ammonium is to be understood the following
process for the manufacture of Prussian blue :-
The cyanide of ammonium is passed into a dilute solution of iron and hydrochloric
acid maintained at a temperature of 60°, Prussian blue being formed and chloride of
ammonium which remains in solution. By adding iron and hydrochloric acid to the
The Prussian blue
liquid the manufacture of Prussian blue is rendered continuous.
is deposited in the form of blue powder and the chloride of ammonium is separated
by crystallization.
The remaining gases are returned in the usual manner to a gas holder, but in this
instance the ammonia is only recovered in a state of combination. Ferri-cyanide is
obtained by treating ferro-cyanide by the ordinary processes.
It is the process in its entirety and details which we desire to patent for employ-
ment in the preparation of nitrogen products derivable either directly or by transition
from cyanogen and ammonia.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what
we claim is :-
1st. The process of fixing nitrogen which consists in causing a mixture of nitro-
gen, hydrogen, and ammonia to re-act on carbon at a high temperature so as to bring
about the formation of an acetylenic carbide of ammonium in which free nitrogen
becomes fixed thus producing cyanide of ammonium.
2nd. The process herein described of producing cyanides and their compounds such
as ferro and ferri-cyanides, etc., as well as all nitrogen products derivable either
directly or by transition from cyanogen and aminonia.
Dated this 6th day of Novambar 1907
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.