Download 1.4. Nomenclature 2. LABORATORY

coined the word catalysis to tiescribe this phenorncnon, whilc more than a c e n t u v
was to pass before selective heterogeneous catalytic rwctions were studied e x h a w
tively.
1.4. Nomenclature
T h e work of the Dutch chemists was quickly recognised as a substantial advance
and stimulated a great deal of further experimental work on ethylene itself and on
its derivatives, particularly by Faraday, Hennel, Dumas, Liebig, Regnault and
others. T h e Dutch chemists' memoir was communicated to the Paris Institute in
1795 by de Fourcroy, and in this communication ethylene is referred to as 'gaz
hydrogkne carbon6 huileux' or simply 'gaz huileux'. T h e name was subsequently
changed by de Fourcroy to 'gaz olkfiant', meaning oil-producing gas in reference
to its reaction with chlorine to produce an oily product. This name, which in
English became 'olefiant gas' and in German 'olbildendes gas', ultimately emerged
ZLS the generic term for unsaturated hydrocarbons as a whole. Subsequent investigators applied other names for ethylene, including etherin and elayl, the latter being
used by Berzelius. Liebig coined the word 'ethyl' for the C,H5 group, and the word
ethylene was derived therefrom. Later Laurent proposed the name ethene, which
was adopted as part of thc Geneva Nomenclature. I n fact, however, this name is
little used in practice, and ethylene is usually preferred. All these names, apart
from elayl, stem from the name 'ether', which in turn is derived from the Latin
name spiritus vini aethereus applied first by Frobenius in 1730."
2.
d
,
I
I
,
LABORATORY PREPARATION A N D I N D U S T R I A L
P R O D U C T I O N OF ETHYLENE
For the preparation of ethylene on n laboratory scale the most convenient methods
arc those based on the dehydration of ethanol, although satisfactory methods also
exist for preparing ethylene from ethylcrlc dibromide, from ethyl halides, and
also from acetylene by hydrogenation.
2.1. Methods
of Preparation from Ethanol
T h e method of preparation of ethylene first described by the Dutch chemists
in 179j1 consisted of heating ethanol with an excess of sulphuric acid, whereby, in
addition to ethylene, appreciable amounts of ether as well as sulphur dioxide arc
formed. This method continued to be used with minor variations for many decades.
A typical preparation described by Erlenmeyer and Bunte" consisted in slowly
adding a mixture of one part by weight of ethanol and two parts of sulphuric acid
to a mixture of 25 g of ethanol and 150 g ofsulphuric acid, heated to 160-170' in
a 2-3 1 flask, and washing the resulting gas successively with sulphuric acid, caustic
soda and finally again with sulphuric acid.
4
I
Phil. Trans., 1730, 36, 283 ; 1733, 38, 55.
1795, ( z ) , 195, 310, 430.
Ann., 1873, 168, 6 4 ; 1878, 192, 244.
1 Crell's Annalen,
I
LABORATORY P R E P A R A T I O N A N D I N D U S T R I A L P R O D U C T I O N
5
11was latcr found by Moser and Lindinger3 that the addition of small quantities
' certain metal salts, particularly copper salts, to the reaction mixture accelerated
reduction of ethylene, whereas the addition of mercuric oxide and molybdic oxide
rrmoted the formation of sulphur dioxide. By using a mixture of I mol of ethanol
14 per cent concentration) and z mol of sulphuric acid of density 1-84 containing
85-2.0 per cent of copper salt at 145-150°, ethylene was obtained in 15-20 per cent
1c4dand 99 per cent purity. According to Scnderens4 the addition of aluminium
~lphateincreascs the rate of production of ethylene, but the use of this additive
:ISnot favoured by Moser and Lindingcr.7
Ikcause of its many disadvantages, including low yield and appreciable byroduct formation, the sulphuric acid method is now only of historic interest. A
lore satisfactory method involves thc use as the dehydrating catalyst of phosphoric
:id, either in liquid form or more usually dispersed on a suitable porous solid
Ipport. T h e fact that under certain conditions ethylene is evolved by the action
I' phosphoric acid on alcohol was rccorded by Pelouze as early as 1 8 3 3 . T h i s
~cthodwas developed by Ncwth,G who recommended the addition of ethanol drop
y drop into a flask containing phosphoric acid, initially of density 1.75 but previsly concentrated by boiling until its temperature had reached zoo0. From 50-60
11of syrupy phosphoric acid in a 180-ml Wurtz flask, a steady stream of ethylene
thc rate of 15-20 l/hr was obtained by maintaining the liquid temperature bevcen zoo0 and 220". T h e gas obtained after cooling to o 0 to remove condensible
purities was pure ethylene, being completely absorbable by fuming sulphuric
:id. Newth states that 'The process appears to be continuous, and as long as the
rpply of alcohol is maintained the operation will go on without attention, appar~ t l yfor an indefinite period'. Prior vapourisation of the alcohol in such a process
;IS recommended by Clutterbuck and Cohen.7 I t was observed by Weber and
'altons that the addition of small amounts of the sulphates of copper, silver and
uminium markedly increased the activity of phosphoric acid in thc dehydration
ethanol at Z I ~ Z ~ O O .
The disadvantages associated with the use of a corrosive liquid medium led to
le use of phosphoric acid absorbcd, or suspended, on a porous solid support,
urnice being generally used for this p u r p ~ s e .By
~ passing ethanol vapour over a
~talystof pea-sized granules of pumice previously impregnated with pyrophoshoric acid at temperatures of 280-3o0°, Moser and Lindinger obtained over 50
:r cent yields of ethylene of approximately 99.6 per cent purity; a slight volatility
'phosphoric acid under such conditions was noted by these investigators.
The early observations of the Dutch chemists on the catalytic properties of pipe
ay, alumina and silica in promoting the conversion of ethanol to ethylene do not
)pear to have been followed up for more than a century. However in the first
'
:' iMonatsh. Chem., 1923,44, 141.
.' Compt. vend., 1910,151, 392.
Urn.Chim. Phys., 1833,52, 37.
" J . Chem. Soc., 1910,79, 915.
J . Chem. Soc., 1922,121, 124.
J. Phys. Chtnz., 1930,34, 2693.
!' Backhaus, U S P
1,372,736(1921).
6
H I S T O R Y 01: E T H Y L E N E A N D I T S I N D U S T R I A L U T I L I S A T I O N
decade of the present century the investigation of the effects of various catalysts on
the vapour phase decomposition of ethanol was vigorously pursued by a number
of workers. Grigoriefflu and also Ipatievll independently demonstrated the valuc
of alumina as a specific dehydration catalyst for the conversion of ethanol to ethylene
at around 350". Later Sabatier and Mailhe12 made a careful study of various oxide
catalysts, and showed that thoria at 300-4o0° was virtually IOO per cent efficient
as a dehydrating catalyst, whereas alumina and blue tungstic oxide gave products
corresponding to 98.5 per cent dehydration and 1.5 per cent dehydrogenation. In
experiments using 2-3 mm granules of prccipitated alumina, Moser and Lindinger"
found that at 400" some ether as well as ethylene was formed; after eliminating
impurities by washing, the cthylene containcd 2.8-3.6 per cent of gas not absorbable
in fuming sulphuric acid. Sprentl" reported that dehydration of ethanol over
amorphous alumina at 360" gave ethylene containing some ethcr, while GorislQ
also investigated the catalytic activity of alumina and pumice mixtures, for which
a suitable operating temperature range was 430-450'. A comparative study of
various metal oxide catalysts for this reaction was made by Engelder.15
An interesting method of dehydrating ethanol was discovered by Ebelmen16 who
found that ethyl borate could be decomposed by heat to yield ethylene and that the
reaction could be the basis of a truly catalytic process. For example, by heating
four parts by weight of boric acid and one part of ethanol, a good yield of ethylene
was obtained; the residue could be re-used to treat more ethanol, while the ethylene
produced, after washing with water, was very pure.17
Preparation o f Ethylene from Acetylene
T h e catalytic hydrogenation of acetylcne can under appropriate conditions give risc
to relatively pure ethylene. This reaction was studied by Sabatierla using such
catalysts as reduced nickel, copper and iron. Almost quantitative yields were claimed
by hydrogenation in the presence of j-20 per cent of steam over a catalyst of
palladium supported on kieselguhr,]% method which was later used on a large scale.
Chemical methods of reducing acetylene to cthylene have also been described,
perhaps the most elegant being those based on the reaction of acetylene with
chromous salts. This reaction, discovered by Berthelot,'o was later developed by
Traube and Passarge" who found that aqueous acid solutions of chromous chloridc
reduced acetylene quantitatively to ethylene with c o production of ethane whatsoever.
2.2
Bull. Soc. Chim. fi.,1902,(3), 26, 612;J.Russ. Phys Chew Yoc., 1910,33, 173.
Ber., 1902,35, 1047;1903,36,1990.
'I Am. Chivr. Phys.,1910,( S ) , 2,289.
].'J.Soc. Chem. Ind., 1913,32, 173.
I" Chim. Ind., 1924,11, 449.
l 5J.Phys. Chern., I 917,21,676.
I GJ.p a k t Chem., 1846,37, 347.
fl Villard, Ann. Chim. Phys., 1897, (7), 10,389.
18 Compi. rend., 1899,r28, 1173;1900, 130, 1559, 1629;1900, 131, 187,267.
1"GFarbenindustrie AG, G P 552,008 (1929).
20 Ann. Chim. Phys., 1866,(4), 9,4021 Ber., 1916,
49,1692.
lo
l1
LABORATORY P R E P A R A T I O N AND INDUSTRIAL P R O D U C T I O N
7
Preparation of Ethylene from Halogenated Hydrocarbons
ery convenient method for the preparation of small quantities of very pure
lene is that based on the reaction of ethylene dibromide in alcoholic solution
granulated zinc" or with zinc activated by copper salts, namely the so-called
-copper c o u p l e . " ~ c c o r d i n gto Moser and Lindinger the use of the zincper coupie gives initially a higher production rate than when using zinc alone,
his falls off rapidly. Typically the reaction is carried out by adding loo ml
15 per cent alcoholic solution of ethylene dibromide to 150-200 g of granud zinc in a flask and warming the mixture to 40°. A steady stream of ethylene
roduced at the rate of 7-9 l/hr. T h e gas produced by this method was
mined by Manchot and Brandt," who found that after cooling to --Soo to ree condensible impurities, it analysed 99.0 per cent by bromination. T h e
ence of small amounts of water in the reaction medium was said by
masi2"o
acceleratc the reaction, the ethylene produced being completely
rbed by fuming sulphuric acid. Howover, OttZ6 reported that ethylene
oduccd by the method of Gladstone and Tribe contains a small amount of
hane.
nder the same conditions ethylene diiodide" behaves similarly to ethylene
omide, but cthylene dichloride" was found to rcact only slowly to form a gas
-reactive with bromine.
he production of ethylene, usually in minor amounts, has been obscrved in the
tion of ethylidene dichloride with sodium" and by rcacting ethylene dibromide
copper, potassium iodide and water at 27s0,but ncither method is of preparavalue.
While the ~roductionof ethylene in the thermal dehydrochlorinatio of ethyl
ride vapour in the presence of pumice at high temperatures was recorded by
~ , 'this
~ reaction is more effectively carried out by the method of Sabatier and
lhe"9 in which ethyl chloride vapour is led over a barium chloride catalyst at
3o0°.
f historic interest, though of no preparative value, arc the observations of
ben and Rossi,30 confirmed by Nef,z1 that reaction of ethyl bromide with
holic potash gives o11Iy small amounts of ethylene; of Denham" that
ating ethyl iodide with cuprous oxide yields a gas rich in ethylene; and of
kow33 that ethylene is formed by heating ethyl iodide with lead oside at
0.
Sabanejeff, Ber., 1876,9, 1810;J . Rtus. Phys. Chcm. Soc., 1877,9 , 3 3 .
Gladstone and Tribe, J . Chem. Soc., 1875,27, 406.
Ann., 1909,37,287.
B t t l l . Soc. chim. Fr., 1874,21, 549.
Helv. Chim. Acta, 1924,7, 886.
Tollens, Ann., I 866,137,31I.
Ann., 1901,318, 13.
Compt. rend., I 905, 141, 238.
" Ann., 1871,158, 166.
Ann., 1901,318, 13.
"J. Chem.Soc., 1878,33, 545.
' Ber., 1878, 11,414.
"
8
H I S T O R Y OF E T H Y L E N E A N D I T S I N D U S T R I A L U T I L I S A T I O N
2.4. Preparation of Ethylene by other methods
Although many different reactions giving rise to certain amounts of ethylenc,
usually in admixture with other gases, have been described, almost none are of
value for the preparation of ethylene on a small scale, although methods based on
the thermal decomposition of hydrocarbons are, of course, of prime importance in
industrialpractice. Some of the more interesting reactions may be mentioned briefly:
B y thermal decomposition of organic compounds. T h e formation of ethylenc
as one of the products of thermal decomposition of hydrocarbons and alsu
of other organic compounds was the subject of numerous investigations in thc
'
last century. Of special interest historically are the observations of Berthelot" and
of Worstall and Burwell" on the production of ethylene, along with other gaseous
products, in the thermal decomposition of ethane and heptane respectively. I t was ,
not, however, until about 1920, that pyrolytic processes began to be the subject of
intensive investigation, and a more thorough understanding of the mechanism of
thermal decomposition processes gradually developed. It was at this time that the 1
cracking of ethane for ethylene production was initiated. From the point of view
of small scale preparation of ethylene, such thermal reactions are of little value,
since they invariably give rise to difficultly separable mixtures of gaseous products.
I
2.4.". From carbides. Gases containing ethylene are obtained by decomposing I
with water certain metallic carbides especially uranium carbidc.36
2.4.1.
2.4.3 B y electrolysis. T h e co-production of ethylene alone with ethane, carbc n
dioxide and hydrogen has been reported in the electrolysis of aqueous alkaline
solutions of potassium acetate by Bourgoin,37 of aqueous alkali propionate solutions
by Hopfgartner,Ja and particularly of slightly acid aqueous solutions of potassium
succinatc by Petersen,:'Q who obtained ethylene yields of up to 24 per cent at 0''
and high salt concentrations.
2.4.4. B o m carbon disulplzirle and l y d r o p z sulphide. Berthelot*o observed that
ethylene was one of the products obtained by passing a mixture of carbon disulphide and hydrogen sulphide (or phosphine) over red hot copper, although higher
yields wereobtainedfrom dry mixtures of carbon disulphide, hydrogen sulphide and
carbon monoxide over red hot iron filings.
'
1
2.4.5. From carbon monoxide--hydrogen mixtures. By passing a mixture of equal
1,
volumes of carbon monoxide and hydrogen at 95-100" over a catalyst prepared
by impregnating coke with nickel and platinum~salts,Orlov41 obtained a gaseous
containing up to 8.3 per cent of ethylene.
I
Cotnpt. rend., 1898, 126, 567.
Amer. Chem. J.,1897,19,815.
3 6 Moissan, Bull. soc. chim. Fr., 1897,( 3 ) , 17, 15; Berthelot, Cotnpt. rend., 1901, 132, 281.
3' Annls. Chim. Phys., 1868,( 4 ) , 14,157.
3s ~Wonatsli.Chem., 191I , 32, 522.
39 2. phys. Chem., 1900,33, 701.
40 Ann. Chem., 1858,18,188.
41 Ber., 1909,42,893.
34
36
i
LABORATORY PREPARATION AND I N D U S T R I A L P R O D U C T I O N
0
2.5. Methods for the Industrial Production of Ethylene
For the production of ethylene on an industrial scale the main methods used include
the catalytic dehydration of ethanol, the hydrogcnation of acetylene, the cracking
of hydrocarbons higher than methane and the high temperature, or electric arc,
cracking of hydrocarbons in which ethylene is a co-product with acetylene. In
addition, it has been recovered on an industrial scale from by-product gases of
the petroleum rcfinery industry and from coal carbonisation gases such as coke oven
gas. Detailed rcviews of thcse procedures form the subject matter of Chaps. 2
and 3, b i ~ they
t
will be outlined here briefly, mainly from an historical standpoint.
2.6. Production from Ethanol
Industrial methods of dehydrating ethanol to cthylenc have all been based on the
passage of ethanol vapour over solid contact catalysts at elevated tempcratures, the
preferred catalysts being alumina or phosphoric acid on a suitable support.
Catalytic dehydration over amorphous alumina at 360' was used by the Elelrtrochemische Werke at Bitterfeld before World War I for the production of cthylcnc
needed as an intermediate in the manufacture of ethane for refrigeration."quring
that war, several processesi:' were dcveloped in the combatant countries for the
production of ethylene needed for the manufacture of mustard gas. T h e mcthod
used in Germany cmployed an alumina catalyst heated to 380--400°, when a 90 per
c.cnt yield of ethylene was obtained. T h e catalyst had a life of IG-20 days. I n the
~ncthoddeveloped in the USA at this timc, a mixture of alcohol vapour and steam
was passed over a kaolin catalyst packed in 3 in. diameter iron tubes and heatcd
to 500-600". T h e yield was 85 per cent of the alcohol used whilc the ethylene purity
w;ts 92-96 per cent. On the other hand, the process used in Britain during this war
was based on a catalyst of phosphoric acid supported on coke granules.
Large quantities of ethylene have been, and still are, produced by the catalytic
clchydration of ethanol. For example, in 1955 no less than 15,ooo tons of ethylene
were produced in the U S A from this source. In most industrialised countries this
n~cthodhas now declined or has ceased altogether. However, in some countries
wltcre molasses is chcaply available, new plants for ethylenc production based on
li-rrncntation ethanol arc still being erected.
2.7. Production from Acetylene
lais is method of production was developed in Gcrmany and applied on a large scale
ing World War 11; in 1943 for instancc it supplied over 30 per cent of the total
ylene consumed in that country. I n this method, acetylene mixed with excess
lrogen and some steam was passed over a catalyst of palladium on kieselguhr at
lilt 270'. T h e yield of ethylene was 8e-85 per cent with 1.5-2-5 per cent consion to ethane. T h e process was operated at five plants, the largest being that
^;cndorf.'4
,'
"
Sprenf J . Soc. Chem. Ind., 1913,32, 1 7 1 .
L!llrnann Encyklopiidie der Tech .Chcm. (2nd edn. 1928), I, 752-3.
HlOS Final Reports Nos. 1411,1058; F I A T Final Report No. I 107.
HISTORY OF ETHYLENE A N D ITS INDUSTRIAL UTILISATION
I0
2.8. Ethylene from Coal Carbonisation Gases
T h e ethylene content of coke oven gas is somewhat variable, depending on the type
of coal carbonised and conditions of carbonisation. According to Bronn,4' an
average figure for ethylene content is 1.6 per cent by volume.46 Analysis of various
coke oven gases in France carried out by Lebeau and DamiensQ gave figures varying
from 1.1-3.3 per cent by volume of ethylene, with around 0.1 per cent of propylene.
On the other hand coke oven gas supplied from the Saar to the Oppau plant of the
1. G. Farbenindustrie during World War I1 was said to contain 2.6j per cent of
ethylcne and 0 . j per cent of propylene.1"
During the period after World War I, coal carbonisation gases and particularly
coke ovcn gas were developed as a source of hydrogen for ammonia production.
This involved separating the constituents by low temperature liquefaction, for
which the Linde-Bronn system was used in Germany and the Claude method in
France. As a by-product of this separation operation there was obtained an ethylene
concentrate containing 30-40 per cent ethylene (Linde-Bronn), which was thereafter
concentrated in Gcrmany to about 90 pcr cent, and in some cases to 99 per cent
concentration. T h e Compagnic de BCthune in France, using the Claude process,
obtained from coke oven gas containing 2-3 per cent of ethylene, a C , fraction with
an ethylcne content of 20-30 per cent, and it was this fraction which u a s utilised
for ethanol production.'"n
Gcrnlany coke oven gas was the source of over 18,000
tons of ethylene (17 pcr cent of total ethylene production) in 1943.
A considerably richer source of ethylene was the so-called oil gas produced
around the end of thc ccntury by cracking petroleum oils in retorts for the purpose
of cnriching or carburetling low calorific value gaseous fuels. Such gases typically
contained 20-zj per cent of ethylene and 13-16 per cent of propylene as well as
some C, hydrocarbons and constituted the raw material used by Fritzschejo for
the manufacture of ether in the U S A during the early 1900s.
2.9. Production by Cracking of Ethane and High Hydrocarbons
Since the early pioncering work of the Union Carbide Corporation on the production of ethylene from ethane or ethane/propane mixtures, these hydrocarbons have
constituted the most important feedstocks for ethylene production in thc U S A . I n
Europe and Japan, the cracking of naphtha is the main source of ethylene for
industrial purposes.
In conilcction with cthnne cracking, it is interesting to note that during World
War 11, four units, cach with a capacity of 4,000-5,000 tons/annum of ethylene,
wcrc crected in Gcrmany on the basis of the oxidative cracking of ethane at temperatures of 700-8o0°,"1 and in 1943 some 14,ooo tons of ethylene were produced by
4".
I
"
I
angew. Clzem., 1929, 42, 760.
j w o c k , Z. angew. Chem., 1924, 37, 252.
47 Compt. rend., i 920, 171, I 38 j.
B I O S Final Report No. 876.
Vallette, Chim. at I d . , 1925, 13, 718.
Chemisclz~Ind., 1912, 35, 637.
61 B I O S Final Report No. 1058.
DEVELOPMENT I N T H E NINETEENTH CENTURY
II
\his method based on ethane derived from Fischer-Tropsch plants. Thermal
cracking of ethane, though developed on a large experimental unit at Leuna, was
ticver actually practised in Germany at this time.
3. DEVELOPMENT OF ETHYLENE CHEMISTRY I N THE
NINETEENTH CENTURY
1 he nineteenth century witnessed the rise of organic chemistry as an important
Ijranch of chemical science with its own organised body of knowledge and theoretical
principles. T h e first half of the century was a period in which many important
~liscoveriesand experimental observations were made, including the epoch-malting
synthesis of urea by Wohler in 1828,' but it was also a period of considerable
confusion on the theoretical side. It was not indeed until after the middle of the
century that certain basic principles on which organic chemistry has since been
1)itscd were clearly enunciated. For example, the quadrivalency of carbon and the
possibility of carbon atoms being linked tigether by valency forces was recognised
intlcpendently by Kelrulk and Couper; the latter first introduced the use of dotted
lil~csto represent valency bonds in 1858.2
' r h e existence of unusual reactivity in con~poundssuch as ethylene and acetylene
\v;ls interpreted by ICekulC as due to the affinity units between adjacent carbon
;~lonlsbeing in a certain sense free. Such compounds he believed should be called
' I W L saturated'. The esistence of double bonds in ethylene and a treble bond in
.~t,ctylenewas first clearly stated by Erlcnmeyer in 186e"
'I'he interest in ethylcne chemistry sparked off by the preparation of pure cthylene
I)\! the Dutch chemists resulted in a series of researches associated with many famous
Il;lllles, including those of Faraday, Hennel, Berthelot, Wurtz, Carius, Liebig,
I<c.rrllault.Dumas, Wohler and others. The work of Berthelot in this field, which
W A S pursued over a period of several decades, is remarlcable for its very wide scope.
I .
3.r. Reaction with Sulphuric Acid
' 1 ' 1 1 ~ reaction between ethylene and sulphuric acid was studied in Faraday's laboralory by Hennel in the 1820s. In 1826 he published" his work on the formation
I'nrlu ethanol and sulphuric acid of ethylsulphuric acid (then called sulphovinic acid)
wl~ichhe regarded as a compound of sulphuric acid with carbon and hydrogen, the
Ii111crelements existing in the same proportions as in ethylene. Hennel identified,
lllough perhaps on slender evidence, sulphovinic acid as the product of absorption
111cthylene in concentrated sulphuric acid. I n a later paper" he showed that sulphor i ~ ~acid
i c (with other products) is formed from ether and sulphuric acid, and that
il is I-cadily converted into ethanol and sulphuric acid by dilution with water. Thus
I - ~ I W I - may be formed from ethanol and vice versa. Since ethylene can be absorbed
I
"ltrtl. Phys., 1828,
"
I ' : ~ r t i n ~ t o nA, History of Clie?rristry, Vol. I V (Macmillan & Co., London, 1964)
'I
I
12,253.
I'lril. 'I).ms., 1 8 2 6 , 116,240.
I'lril. 'I'rcrrru., 1 8 2 8 , 118, 305,