IMPROVEMENTS IN OBTAINING AMMONIA
Year: 1878

page_text: LETTERS PATENT to Charles Albert Fawsitt, of Manchester, in the County
of Lancaster, Analytical Chemist, for the Invention of "IMPROVEMENTS IN
OBTAINING AMMONIA."
Sealed the 1st July 1879, in pursuance of an Order of the Lord Chancellor, and
thOLL AL
10-0
Sealed the 1st July 1879, in pursuance of an Order of the Lord Chancellor, and
dated the 0th November 1878.
PROVISIONAL SPECIFICATION left by the said Charles Albert Fawsitt at
the Office of the Commissioners of Patents on the 9th November 1878.
CHARLES ALBERT FAWSITT, of Manchester, in the County of Lancaster, Analy-
tical Chemist. "IMPROVEMENTS IN OBTAINING AMMONIA."
This Invention has for its object the obtainment of ammonia in an improved,
simple, and very economical manner, and it consists in first passing nitrogen over
or in contact with oxide, or carbonate, or other suitable compound of sodium or of
potassium combined, or mixed, or associated with carbon in the form of charcoal, or
in any other suitable form; and in, secondly, passing steam over or in contact with
the same substances after the nitrogen has acted on them for a shorter or longer
time. Cyanides or similar compounds are formed by the first part of the process,
and these compounds are decomposed by the action of the steam so as to yield
ammonia. The ammonia may be absorbed by an acid or it may be collected in any
other convenient way.
The nitrogen may be obtained from atmospheric air by means of any of the
known processes for abstracting oxygen from the air. The oxide or compound of
sodium or potassium and carbon must be in a heated state whilst the nitrogen or
steam is being passed over them, and they may be placed in pipes, retorts, or other
vessels of iron or earthenware heated externally. During the action of the nitrogen
about a bright red heat should be employed, but about 600 degrees Fahrenheit is
sufficient for the second part of the process.
Instead of nitrogen air may be employed, having some only or none of the oxygen
removed from it, and instead of using cyanides formed in the manner bereinbefore
described, cyanides formed in any suitable known way may be employed. Finally,
instead of the steam, or of some of it, hydrogen may be used.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Albert Fawsitt in the Great Seal Patent Office on the 1st
July 1879.
CHARLES ALBERT FAWSITT, of Manchester, in the County of Lancaster, Ana-
lytical Chemist. "IMPROVEMENTS IN OBTAINING AMMONIA."
My said Invention has for its object the obtainment of ammonia in an improved,
simple, and very economical manner, and in carrying it into effect nitrogen is passed
over certain suitable compounds of sodium or of potassium combined, or mixed, or
associated with carbon in the form of charcoal, or in any other suitable form, the
cyanogen compounds formed by the action of the nitrogen being subsequently
treated with steam, which causes ammonia, or a compound or compounds thereof to
be evolved.
The nitrogen may be obtained from atmospheric air by means of any of the
known processes in which oxygen is abstracted from air. Instead of simple nitrogen
air may be employed having some only or none of the oxygen removed from it, and
instead of the steam or of some of it hydrogen may be used.
It has for many years been well known that ammonia can be obtained by
employing the nitrogen of the atmosphere for that purpose, but although several
different processes have been proposed and tried I am not aware that any has bitherto
been practically carried out so as to obtain ammonia in that way in a manner to
compete commercially with the supply of ammonia from other sources.
The earlier attempts to utilise the nitrogen of the atmosphere appear to have been
mainly directed to the obtainment of cyanogen (chemically symbolised by the
letters CN, indicating an atom of carbon and an atom of nitrogen combined) or
cyanides (compounds of cyanogen with metals or bases) which are valuable chemical
products, and in some of the attempts to obtain these products ammonia was sub-
stituted for air as the source of the requisite nitrogen. In one case, the process being
described in the Specification of British Letters Patent, No. 1027 of 1860, granted
to Clark for Margueritte and Sourdeval's Invention, it appears to have been
expected that ammonia would be formed by the union of the nitrogen of the air
with hydrogen without the formation of an intermediate compound such as cyanogen
or a cyanide, and at one operation or stage of process; and it is claimed that one of
the uses of the ammonia so formed is for preparing cyanides and ferro-cyanides. In
other cases also the obtainment of ammonia by employing the nitrogen of the air
appears to have been expected without the intermediate formation of cyanogen or
cyanogen compounds even when the process comprises two stages, the nitrogen
being assumed to be temporarily united with or absorbed by a substance such as
baryta, and to be subsequently yielded up by such substance in order to be com-
bined with hydrogen separated from steam.
In some cases it has been proposed, but not with any practical success so far as I
am aware, to utilise the nitrogen of the air by first forming cyanides with basic
substances and subsequently treating such cyanides with steam so as to obtain
ammonia.
In my improved process or processes certain cyanogen compounds are formed pre-
paratory to the obtainment of ammonia, as can be proved by chemically testing the
substances prior to the final treatment with steam.
My process or processes are characterised by various improved details which
have an important influence in securing satisfactory and economical results, and I
will now proceed to particularly describe the manner in which I believe my Inven-
tion may be best carried out in practice.
I do not claim any particular process for separating nitrogen from the air for the
purposes of my Invention, but I prefer in obtaining the nitrogen to proceed as
follows: I cause air to be forced or drawn by means of a pump, aspirator, or the
like through sulphuric acid or other absorbent of moisture, in order to dry it if

page_text: necessary, and I then pass the air through a retort, kiln, furnace, or other vessel
containing coke or any other suitable and convenient oxidisable substance heated
to dull redness, or 900 to 1000 degrees Fahrenheit. In this process the oxygen of
the air combining with carbon forms carbon dioxide (otherwise known as carbonic
acid), thus C+20=CO₂, and some carbon monoxide is formed, thus, CO₂+C=200.
The nitrogen mixed with the carbon oxides is by preference next passed through
lime suspended in water which absorbs the carbon dioxide; and the nitrogen,
although still mixed with a little carbon monoxide, may then be at once led into
the apparatus used in carrying out my Invention. I however prefer to store the
nitrogen in a gas holder, so that its preparation may be conducted quite indepen-
dently of the other operations, and so that it can be used at different times or at
different rates to those of its preparation.
Instead of obtaining the nitrogen from ordinary atmospheric air, it may be
obtained from the waste gaseous products of some chemical manufactures, it being
originally derived from the atmosphere, but care must be taken to separate from it
when so obtained any gases associated with it of a nature to interfere with its
intended use.
The particular compounds of sodium or of potassium which I use in carrying out
my Invention, are the carbonates and sulphides thereof, and I will first describe my
process as effected with sodium carbonate Na,O,CO,.
I mix charcoal or any other suitable carbonaceous matter with the sodium
carbonate, the latter being in a state of fine powder or in solution. I prefer to
form a strong hot solution of sodium carbonate by taking common soda crystals
and melting them in their own water of crystallisation, and I dip the charcoal in
pieces of any convenient size into this solution, the pieces becoming coated externally
without the solution penetrating inwardly.
The coated or prepared charcoal when quite dry is put into a retort or any
suitable vessel arranged so as to be heated externally, and capable of withstanding
the necessary heat. The retort or vessel may be made to rotate with the view of
expediting the reactions which take place in it by continually turning over, and
thereby agitating the materials, or for that purpose rotating agitators may be used
in a stationary retort or vessel. The prepared charcoal being heated in the retort
or vessel to a bright red heat or somewhat less, say, 1800 to 2000 degrees
Fahrenheit, the nitrogen is passed through, being by preference heated either by
separate heating apparatus, or by a part of the retort itself. Combinations are
then formed between the sodium, carbon, and nitrogen, and some oxygen, there
being produced cyanide and cyanate, the latter differing from the former in having
an atom of oxygen. The reactions taking place I believe to be represented by
these equations:-
Na,O,CO₂+4C+2N = 2Na,CN +3C0
that is, sodium cyanide plus carbon monoxide, and
Na₂O,CO₂+2C+2N=2Na,CNO+CO
that is, sodium cyanate plus carbon monoxide, I prefer to conduct the process so
as to make as much cyanate as possible in preference to cyanide, and with this view
I take care that the heat does not become too great, and that the supply of nitrogen
is plentiful. The cyanate is more advantageously decomposed in the next stage of
the process than the cyanide. The carbon monoxide evolved in the reaction
together with any of the nitrogen which does not take part in the reaction, may be
led into a chimney or otherwise discharged into the atmosphere; or the carbon
monoxide, being combustible, may be utilised in the furnace; or again, the carbon
monoxide and nitrogen may be drawn off into a gasholder for the purpose of saving
the nitrogen, and the carbon monoxide may, in that case, be utilised in obtaining
fresh supplies of nitrogen by burning it with the addition of air necessary to
convert it into carbon dioxide, the nitrogen of such air being added to that saved
with the carbon monoxide, and the carbon dioxide formed being removed by
passing the mixed gases through water in which lime is suspended.

page_text: In all cases when about to introduce the nitrogen into the retort for the purpose
of acting on the charcoal prepared with sodium carbonate, I consider it advan-
tageous to have in the retort a small quantity of sodium cyanide, or by preference
cyanate already formed in a previous operation or otherwise, as I find the presence
thereof favors the action which is desired to take place.
When it is considered that the action of the nitrogen has been continued long
enough its introduction is stopped, and the materials are allowed to cool down to a
temperature of about 600 degrees Fahrenheit; steam is then introduced into the
retort, and causes the evolution of ammonia and ammonium carbonate. The
reactions taking place I believe to be represented by these equations
Na CN +2 H₂O = Na CHO, + NH.
:-
The cyanide yielding formate and ammonia, which formate is decomposed thus:-
2 Na CHO, Na, OCO₂ + CO + H₂.
-
The cyanate yields ammonium carbonate thus:-
2 Na CNO + 4 H₂O
=
Na, OCO, + (NH,), CO,.
The ammonia and ammonium carbonate may be collected, and the ammonia
combined with an acid or with water, or otherwise utilised in any of the well
known ways.
It is however always desirable to first pass the ammonia and
ammonium carbonate through a solution of a caustic alkali or alkaline earth, in
order to separate the carbonic acid, and also the small quantities of hydrocyanic,
cyanic, or cyanuric acids which are generally formed in the reaction with the
steam.
The sodium carbonate remaining in the retort serves for a repetition of the
processes. The charcoal or carbonaceous matter is however partially consumed, and
when it is considered to be as far exhausted by repetitions of the process as is
desirable, fresh supplies of it must be prepared with the sodium carbonate and be
put into the retort.
When using potassium carbonate the procedure is the same as with sodium
carbonate, and the reactions are the same all as hereinbefore described.
It is advantageous after stopping the introduction of nitrogen into the retort
when using either sodium carbonate or potassium carbonate, and before lowering
the temperature preparatory to the introduction of steam to pass oxygen or air
through the retort, for the purpose of converting any cyanide into cyanate.
In order to save the time required for cooling down the retort from the higher
to the lower of the two temperatures employed and for heating it up again, it will
in practice be advantageous to employ separate retorts for the two temperatures,
and to transfer the materials from one to the other, one retort or set of retorts
being kept at one temperature, and the other retort or set of retorts at the other
temperature.
When using sodium sulpbide or potassium sulphide, the former of which may be
taken in the form of the black-ash of the soda manufacture, sulpho-cyanates, and
possibly also at the same time cyanides and cyanates, are formed by the treatment
with nitrogen, and these yield ammonia or compounds thereof when subsequently
treated with steam, the procedure and reactions being similar to those hereinbefore
described, with reference to the use of sodium carbonate.
Having thus particularly described my said Invention and the manner of per-
forming the same, I have to state that I do not restrict myself to the precise
details herein before described, but that what. I believe to be novel and original, and
claim as the Invention secured to me by and in terms of the hereinbefore in part
recited Letters Patent is,-
1. The use of sodium carbonate or potassium carbonate in the process wherein
nitrogen obtained from the atmosphere is used to form cyanates with or without
cyanides, which cyanates and cyanides are treated with steam to yield ammonia or
compounds thereof, as hereinbefore described.

page_text: 2. The use of sodium sulphide or potassium sulphide in the process for
obtaining ammonia, hereinbefore described.
3. The process herein before described for obtaining ammonia by using the nitrogen
of the atmosphere, such nitrogen alone or mixed with oxygen being first made to
act on a mixture or combination of charcoal or other suitable carbonaceous matter,
and sodium carbonate or potassium carbonate, or sodium sulphide or potassium
sulphide, with the aid of a temperature of 1800 to 2,000 degrees Fahrenheit, and
the cyanogen compounds thereby formed being subsequently acted on by steam
with the aid of a temperature of about 600 degrees Fahrenheit, substantially as
herein before described.
4. The addition of a small proportion of a previously formed cyanogen compound
to the materials about to be acted on by the nitrogen, as and for the purposes
hereinbefore described.
5. The working of the stage of the process in which nitrogen is employed to act
on sodium carbonate or potassium carbonate, so as to favor the formation of
cyanates rather than cyanides, by maintaining a plentiful supply of nitrogen, and
keeping the temperature not higher than what is necessary for the reaction, as
liereinbefore described.
In witness whereof, I, the said Charles Albert Fawsitt, have hereunto set my
hand and seal, this Twenty-eighth day of June, in the year of our Lord One
thousand eight hundred and seventy-nine.
CHARLES ALBERT FAWSITT. (L.S.)