Obtaining Ether from Gases containing Ethylene and Apparatus therefor.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Obtaining Ether from Gases containing Ethylene and Apparatus
therefor.
I, DR. PAUL FRITZSCHE, of Bachstrasse 26, Essen, on the Ruhr, Germany,
Chemist, do hereby declare the nature of this invention to be as follows:-
If gases containing ethylene such as ordinary coal gas, or coke oven gas
be treated with concentrated sulphuric acid in order to remove ethylene from the
same by passing the gas through several wash bottles filled with acid, it is re-
marked that the acid first becomes yellow, then brown, and thickens considerably.
On continuing the passage of the gas there separates itself upon the surface of
the fluid an oily or resinous layer. These separations arise from a condensation of
the products which are hydro carbons of high molecular weight which are formed
from simple combined component parts of the gas in the presence of sulphuric
acid, and which dissolve in the acid. The greater part of the condensation pro-
ducts separates in the first washing vessel which is easily proved by ascertaining
the increase in weight thereof. The succeeding vessels contain a less discoloured
and thickened acid. If the dark brown thick acid he examined for its contents
of ethyl-sulphuric acid, by decomposing the same with water, distilling, and
determining the alcohol in the purified distillate by determining the specific weight,
considerably less ethyl-sulphuric acid is found than may be found in one of the
following vessels whose acid shows very little discolouration. It is obvious from
this that the condensation products are more easily removable from the gas than
the ethyls and that they influence the absorbent capability of the sulphuric acid
for ethyls. If therefore lighting gas, coke oven gas or similar gases should be
treated for obtaining ethyl-sulphuric acid, it is first requisite to remove as com-
pletely as possible the condensable hydro carbons. This need not necessarily be
effected by means of concentrated sulphuric acid because moderately diluted acid
effects the separation, especially when warm. At the ordinary temperature the
combination of ethylene with sulphuric acid proceeds very slowly. If however
the acid be heated the action is very much quickened. On using sulphuric acid
of 95% hydric sulphate I have found the relation of the rapidity of absorption
at 150 to that at 1100 centigrade to be as 1 to 30, that is in a given time and with
a surface of equal size of acid at 110° centigrade, 30 times as much ethylene is
absorbed as at 150 centigrade. At 140° centigrade the proportion is as to 50,
and this proportion can through further increase of temperature be still further
increased. The limit of the temperature available finds its maximum t
point of decomposition of the ethyl-sulphuric acid formed. If ethyl-sulphuric acid
lone or mixed with sulphuric acid be heated for a long time at 140° centigrade
there is found a very perceptible decomposition with the development of sulphurous

page_text: acid. The production of sulphurous acid cannot be entirely avoided even at lower
temperatures, but at 120° centigrade it is very small so that no considerable losses
need be expected. In order to obtain ether from the ethyl-sulphuric acid obtained
by the treatment of gases containing ethylene with concentrated sulphuric acid,
I dilute the ethyl-sulphuric acid with a little water and heat it. Thereby is
developed a small quantity of ether but the evolution soon ceases before even the fifth
On dilution with about 10%
part of the quantity contained has been obtained.
of water a mixture of alcohol and ether is distilled over, which already contains
principally alcohol. Even when I conducted the vapours of alcohol and ether
which were developed upon heating a mixture of 50% sulphuric acid with 50%
ethyl-sulphuric acid and dilution with 10% of water through a fractional con-
densing apparatus heated to 40° centigrade no increase of the production of ether
was obtainable. I then conducted the vapours obtained by heating a given
quantity of moderately diluted ethyl-sulphuric acid through an equal quantity of
concentrated acid in order to enrich the vapours in ether. 'n coaequence nere
was a very considerable production of ether obtained, but the production ceased
long before the diluted ethyl-sulphuric acid was really exhausted. I could only
obtain the desired result by the adoption of the following process, namely:-
By decomposing a given quantity of ethyl-sulphuric acid mixed with sulphuric
acid according to the equation:-
2 (C,H,SO)+H,O=)C₂H)₂O+2H₂SO
In carrying the process into effect four receivers are connected together in such
a manner that the vapours developed in the preceding vessel can only escape
through the tube prolonged almost to the bottom of the following vessel; from
the last vessel the vapours pass into a condenser. Each of the four vessels is
provided with an equal quantity of the mixture of sulphuric acid and ethyl-
sulphuric acid to be operated upon. By the addition of water the contents of
the first two and third vessel are so diluted that the percentage of water in the
first amounts to about 33% in the second to 22%, and in the third to about 10%;
the acid in the last vessel remains undiluted.
Distillation is induced by heating strongly in the first instance the contents
of the first vessel whilst at the same time the second vessel is only moderately
warmed. The vapours of ether, alcohol, and water developed after a short time
from the first vessel pass over firstly into the second vessel and cause its contents
also to boil in a short time. Also the contents of the third and fourth vessel have
been in the meantime moderately warmed, so that the vapours escaping from the
second vessel which already contain a quantity of ether soon cause the contents
of the third vessel to boil and still more enriched to pass over into the fourth
vessel. In this the quantities of alcohol are retained and only ether and water
vapour pass into the condenser in which the liquefaction is effected.
From the facts above referred to the following process has been developed
for the production of ether from gases containing ethylene such as lighting gas,
coke oven gas or the like. The gas free from tar, ammonia, benzole and
sulphuretted hydrogen must then be dried. The drying and the separation of the
condensable hydro carbons may be united by allowing the gas to pass through
several washing vessels, in which it is washed with cold, moderately diluted
sulphuric acid or the same warm and more diluted. After all the impurities are
removed in this manner as completely as possible, which might interfere with the
capability of absorption of the concentrated sulphuric acid for ethylene and the
purity of the resulting ethyl-sulphuric acid, the gas is heated in suitable apparatus
and passed into the absorption apparatuses. For this purpose all kinds of apparatus
would be suitable which are thoroughly resistant to hot concentrated sulphuric
acid. The acid flowing from the absorption apparatus which should contain
about 50% ethyl-sulphuric acid is subjected to distillation in an apparatus formed
of several separate boiling or distillation vessels or in an apparatus arranged for
continuous working in which the ether vapours are gradually freed from alcohol

page_text: by passing them through ethyl-sulphuric acid mixtures of consecutively diminish-
ng dilution. The acid leaving the apparatus is again concentrated and used for
refilling the washing and absorption apparatus.
Dated this 12th day of September 1896.
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.
Obtaining Ether from Gases containing Ethylene and Apparatus
therefor.
I, DR. PAUL FRITZSCHE, of Bachstrasse 26, Essen on the Ruhr, Germany,
Chemist, 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:-
When gases containing ethylene, as for example purified illuminating gases or
coke oven gases, or oil gases, are treated with concentrated sulphuric acid for the
purpose of extracting the ethylene by allowing them to pass through several
wash-bottles charged with this acid, the acid is coloured yellow and turns to brown
in continued operation, while becoming more and more viscous. The colouring
and increased density of the acid are caused by products of condensation, hydro-
carbons of greater molecular weight which are formed from simple gaseous
components on contact with sulphuric acid and which dissolve in the acid. The
greater part of the products of condensation separates out in the first wash-bottle
as indicated by the colouring as well as by the increase of weight of the acid, while
the succeeding bottles gain less in colour and weight. After some time as soon
as the products of condensation have collected in sufficient quantity, the separation
of an oily or even resinous layer is noticed on the surface of the fluid in the first
vessel. If this thickened brown coloured acid is tested as to its contents of ethyl
sulphuric acid, it is found to contain less ethyl sulphuric acid, than the acid from
one of the following vessels, which appears less coloured and thickened. The
gas which has passed through the acid is found to be rich in ethylene even if it
has been so thoroughly freed from hydrocarbons yielding products of condensation
as no longer to colour sulphuric acid. The hydrocarbons or the products of their
condensation can thus be more readily removed from the gas than ethylene, but
at the same time they interfere with the absorbing capacity of sulphuric acid for
ethylene. The hydrocarbons are therefore to be first removed from the gases.
Concentrated sulphuric acid is not necessarily employed for this purpose. They
can also be separated by treating the gas with moderately diluted acid, especially
when warm.
The combination of ethylene with sulphuric acid takes place slowly at ordinary
temperature. If however the acid is heated, the combination with the ethylene
is accelerated. By using pure sulphuric acid (ninety-five per cent hydrate) and
pure ethylene I found that the relative rapidity of absorption at fifteen degrees
centigrade to that at 110° centigrade was as one to thirty. That
centigrade thirty times as much ethylene is taken up in the same time by equal
surface moistened with sulphuric acid as at 15° centigrade. At 140° centigrade
the proportion is as oue to fifty. By further increase of temperature the rapidity
of absorption is further increased. Even dilute acid of about eighty per cent
hydrate at temperatures over 100° centigrade eagerly absorbs ethylene."
It might be concluded therefrom that for rapidly and thoroughly freeing a given
quantity of gas from ethylene and obtaining ethyl sulphuric acid it would he

page_text: practicable to heat gas and acid to the highest possible temperature; but this
proceeding is limited by the decomposition of ethyl sulphuric acid occurring at a
higher temperature. If ethyl sulphuric acid by itself is heated for some time
only to 1400 centigrade, there is found in addition to a slight ether formation a
noticeable decomposition accompanied by generation of sulphuric acid, involving
material loss. Neither can this decomposition he entirely avoided if gas and acid
are heated to from 110° to 120° centigrade, but the generation of sulphurous
acid is then so feeble that no material loss need be feared. On heating a mixture
of sulphuric acid and ethyl sulphuric acid for two hours to 120° centigrade only
a slight decomposition of ethyl sulphuric acid could be established after heating.
If the sulphuric acid used for absorption of ethylene is not free from water,
or if the ethylene is not dry, the resulting ethyl sulphuric acid on continued
heating to 1200 centigrade gives off a mixture of alcohol and of ether vapour. On
heating to higher temperature the vapour generation is more copious; but at the
same time this acid absorbs ethylene. Theoretically it might thus be possible
with a small quantity of sulphuric acid to continuously convert an unlimited
quantity of ethylene into a mixture of alcohol and ether.
In my experiments for obtaining ether free from alcohol from ethyl sulphuric
acid I found the following:-Pure concentrated ethyl sulphuric acid, or a mixture
of the same with sulphuric acid on being heated to from 130 degrees to 140
degrees centigrade generates only traces of ether. At higher temperatures
with a generation of sulphuric acid or a mixture thereof with concentrated
sulphuric acid diluted with a small quantity (ten per cent by weight)
of water, very little ether is obtained, but the vapours then contain excess of
alcohol. No matter how the proportion of water of the mixture may be varied no
degree of dilution is obtained at which the yield of ether is even approximately
satisfactory. On the other hand, small quantities of ether are generated even when
the ethyl sulphuric acid is diluted with the same weight of water and heated to
boiling. Here it has no material influence whether the mixture contains much or
little free sulphuric acid. If the proportion of water in the mixture be greator
than fifty per cent the ether formation stops, and only alcohol is then generated.
The experiment of conducting the vapours generated from a mixture of equal
parts of sulphuric acid and ethyl sulphuric acid diluted with ten per cent of water
through a cooler, which was kept at a temperature of 40° centigrade and which
allowed the condensed vapours to run back gave the result that the alcohol the
proportion of which was very high, was condensed, but the quantity of ether was
not increased.
The vapours from heating a certain amount of diluted ethyl sulphuric acid
consisting of ether, alcohol and water will be enriched in etner when they are passed
through an equal quantity of ethyl sulphuric acid. After a short time, however,
when the latter becomes slightly diluted, ethylene is produced and on higher
dilution no more ether is formed.
As in order to avoid loss in consequence of ethylene formation on heating, the
ethyl sulphuric acid must always he diluted with water, I have devised the fol-
lowing process, which allows a given quantity of ethyl sulphuric acid to be
separated into ether and sulphuric acid, according to the equation
2(C2H5OSO2OH)+H2O=(C2H5)2 0+2H2SO4
This process may be carried out in the apparatus illustrated by the accom-
panying drawing.
Four retorts or distilling vessels A, B, C, D, are so connected that the vapours
generated in a preceding vessel can only pass off through a tube reaching close to
the button of the succeeding vessel. From D the vapours pass into an effective
condenser.
Each one of the four vessels is charged with an equal quantity of ethyl sulphuric
acid or of the mixture of ethyl sulphuric acid and sulphuric acid to be operated
on. The contents of A, B and C are diluted with water, so that the proportion

page_text: of water in A amounts to about thirty-five per cent, in B to about twenty-two
per cent, and in C to about ten per cent, while the acid in D remains undiluted.
The distillation is started by vigorously heating the contents of A, while at the same
time the contents of B are but slightly warmed. The vapours escaping in a short
time from A and consisting of alcohol, ether, and water vapour dissolve at first
in the liquid in B, but in a short time the boiling begins here also. The contents
of C and D have also in the meantime been moderately heated, so that the vapours
passing from B which are already richly charged with ether, also promptly effect
a boiling in C and cause the vapours to escape to D. If the ethyl sulphuric acid
employed of high percentage, if it contains little sulphuric acid, the ether vapours
escaping from C pass already at the start unchanged through the acid in D but
the alcohol vapours still passing over with the ether vapours act upon the ethyl
sulphuric acid and are likewise converted into ether, so that the vapours entering
the cooler only contain ether and water vapours. If the ethyl sulphuric acid is,
however, rich in free sulphuric acid, the ether and alcohol vapours passing at the
start from C to D dissolve in the free acid, until equilibrium is attained, when
the ether passes unchanged through the mixture, while the remaining quantities
of alcohol are fully converted into ether. The ether vapours are condensed with
the water vapours in the cooler and led into suitable receptacles.
If the distillation is properly conducted, the contents of I must not increase,
while in B a copious and in C a smaller increase must be noticeable.
If the acid in A is so far concentrated, that the distillation in B no longer con-
tinues without external application of heat, the operation is interrupted, the acid
emptied from A, the contents of B brought into A, of C into B, of 1) into C, and
a fresh supply of undiluted acid poured into D). After the contents of A, B, and C
have been again brought to the above indicated dilution, the distillation can be.
recommenced, and again yields corresponding quantities of ether.
The same
operation can then be repeated as often as desired with the same result, and the
acid emptied from A will always be thoroughly exhausted while ether free from
alcohol is obtained from D.
It is clear that the number of stills is not limited to four nor the dilution strictly
to the above indicated percentage. The process was carried out with the mixture
of ethyl sulphuric and sulphuric acid which contained fifty per cent of ethyl
sulphuric acid and in this case the above conditions were found effective. If
the ethyl sulphuric acid is of high percentage, three vessels can be made to
answer, since in this case the vapours passing from the first vessel are much richer
in etlier and contain less water and alcohol than these, obtained from a weaker acid
diluted with the same quantity of water. In this case the acid with ten per cent of
water (vessel C) can be omitted. In regard to the dilution in the first vessel A,
it is not possible to pass materially below the indicated
suffering loss, since otherwise even in slow distillation the acid attains a high
percentage without
concentration before all the ethyl sulphuric acid is decomposed, so that ethylene
begins to be generated.
From the disclosed facts the following process is devised for obtaining ether
from gases containing ethylene, such as illuminating gas, coke oven gas, wood gas
and the like. The gases freed from tar, ammonia, benzine, and sulphuretted
hydrogen must first be dried. This is most readily effected by combining the
drying and the separation of the products of condensation and treating the gas
either with cold sulphuric acid of about eighty per cent or with diluted sulphuric
acid of less than eighty per cent hydrate at a temperature of from 70°
to 80° centigrade. By this means, also, at the same time the homologues
of the ethylene which may be present, propylene, butylene, and
like, which already in contact with diluted sulphuric acid yield corresponding
alkyl sulphuric acids, are removed from the gas in advance of the ethylene.
the
After all hydrocarbons and other gas components which might oppose the ab
sorbing capacity of sulphuric acid for ethylene and the purity of ethyl-sulphuric
acid are removed in this manner as thoroughly as possible, the gas is heated to

page_text: from 110° to 120° centigrade by being passed through heating chambers provided
with heating appliances. From here it passes into the absorption apparatus, which
are sprayed with hot concentrated sulphuric acid, and in which the temperature
can be kept at from 110° to 120° centigrade. Apparatus resembling scrubbers
and lined with acid resisting stones, which offer the largest possible surface to
the acid and thereby effect a thorough contact between gas and acid, is well
adapted for this purpose. Four to five such apparatuses succeeding one another
are employed, and the fresh acid is continually supplied at the outlet of the last
apparatus at which point the gas leaves the apparatus. The acid collecting on the
bottom of the last apparatus is taken by a pump to the last but one apparatus,
where it again flows against the gas. The like occurs at the other apparatuses so
that the ethyl sulphuric acid containing the highest percentage collects at the
foot of the first apparatus, where the gas enters. This acid is advantageously
brought only to a strength of from fifty to sixty per cent of ethyl sulphuric acid.
The hot mixture of ethyl sulphuric acid and sulphuric acid is led to the dis-
tilling apparatus and transformed into ether. It is advisable to employ for this
purpose an apparatus for continuous operation. The separate parts of the apparatus
are connected with one another as indicated in the drawings. Each still of which
three or more are employed, is provided with special heating arrangement, either
with direct or indirect firing and a regulated overflow or outflow E, through which
the desired quantity of fluid flows uninterruptedly from a higher part of the
apparatus into the next succeeding lower one. With the exception of the highest
still each compartment has water supplied through a pipe or inlet W at the place
where the acid flows in from the overflow. The same enables the proportion of
water of the acid mixture in each separate compartment to be brought to the
required degree. From the highest still where the hot acid continually flows in,
the ether vapours, which on their upward path in the apparatus are entirely freed
from alcohol, pass into the condenser and are condensed together with the water
vapours. The ether obtained is subjected to the usual cleansing by washing with
soda or the like and to rectification." This method of obtaining ether from alcohol
may be used when obtaining ether from sulphuric acid and alcohol in the well
known manner.
The vessels may be heated by suitable means, as by a steamcoil in each vessel
having its inlet and outlet St.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed I declare that what I
claim is:-
1. The method of obtaining ethyl sulphuric acid from gases containing ethylene
which consists in treating the gases freed from tar, ammonia, benzole and
sulphuretted hydrogen with cold concentrated sulphuric acid and then with con-
centrated sulphuric acid or a mixture of sulphuric acid and ethyl sulphuric acid
at a temperature of from 100° to 140° centigrade substantially as described.
2. The method of obtaining ether from alcohol which consists in passing the
alcoholic ether vapours arising from the boiling of ethyl sulphuric acid with water
according to their contents of alcohol and ether through one or more quantities of
ethel sulphuric acid or sulphuric acid or a mixture of the two either concentrated
or decreasingly diluted with water substantially as described.
Dated the 11th day of June 1897.
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.