Mono-Olefins. Chemistry and Technology

1171 Pages·1968·20.587 MB·English

by  F. Asinger (Auth.)

MONO-OLEFINS
CHEMISTRY AND TECHNOLOGY
BY
F. ASINGER
TRANSLATED BY
B.J. HAZZARD
PERGAMON PRESS
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English edition copyright ©1968
Pergamon Press Ltd.
First English edition 1968
This is a translation based on the German book
Chemie und Technologie der Monoolefine,
published in 1957 by Akademie-Verlag,
which has been brought up to date by the author
Library of Congress Catalog Card No. 68-22078
08 011547 0
PREFACE TO THE ENGLISH EDITION
THIS book was first published in German by Akademie Verlag Berlin in
1957. It has now been revised and the literature on the subject up to August
1963, when the translation began, has been taken into consideration.
The number of references given has therefore been considerably increased.
The book has been arranged in a similar way to the German edition. The
reference "see Booh Γ9 given in the text from time to time relates to the
work published in German by Akademie Verlag and published in English by
Pergamon Press under the title Paraffins: Chemistry and Technology.
May I especially express my thanks to Akademie Verlag and Pergamon
Press for the care they have taken in preparing the English edition and for
the skill in the presentation of the printing and of the arrangement of
illustrations.
I am deeply obliged to my former assistant, Dr. Kurt Halcour, for reading
and correcting the proofs.
F. ASINGER
CHAPTER 1
MONO-OLEFINS NECESSARILY ARISING
IN VARIOUS PROCESSES
I. INTRODUCTION
For the purposes of this chapter, the mono-olefins are divided into two large
groups, namely:
1. The lower, normally gaseous or liquid but low-boiling, olefins from ethylene
to the hexenes, and
2. The higher, normally liquid, olefins from the hexenes up to the eicosenes
and those with even higher molecular weights.
By the isolation of olefins will be understood the separation of olefins
arising as unavoidable by-products in any process, while manufacture
means those processes for the production of olefins which are carried out
with the sole purpose of providing industry with this important raw material.
II. THE GASEOUS OR LOW-BOILING OLEFINS
The olefins belonging to this group include ethylene, propene, the butènes
(but-l-ene, eis- and tr&ns-but-2-enes), isobutene (2-methylpropene), and the
pentenes, also called amylenes, such as pent-l-ene, eis- and tTsni8-pent-2-enes,
and 2-methylbut-l-ene, 2-methylbut-2-ene, and 2-methylbut-3-ene. These are
the most important olefinic starting materials for modern chemical industry,
and ethylene is undoubtedly the most valuable. The isolation of these olefins
is carried out on a large scale from the gases which arise in very large amounts
as unavoidable by-products in petroleum refineries in the course of the
manufacture of gasoline by the cracking and reforming processes. Such
olefins are also found in the gaseous reaction products of plants for the
catalytic hydrogénation of oxides of carbon by the FISCHER-TROPSCH
process with cobalt and iron catalysts although ethylene is formed in
concentrations of industrial interest only on working with iron catalysts.
They are not present in the gaseous products of the hydrogénation of
coal, since this process, by its very nature, gives only paraffins. In countries
with little petroleum or natural gases, the gases from low-temperature
carbonization and coke-oven gases, which are produced in large amounts>
are an important source of gaseous olefins. However, their olefin content
Μ ι
2 MONO-OLEFINS, CHEMISTRY AND TECHNOLOGY
is very low, so that their isolation has so far only been profitable in com-
bination with the isolation of the 50% by volume of hydrogen present in the
gas. These sources of olefins give the most important ethylene derivatives
the isolation of which is highly desired at the present time, but their pro-
duction is mainly associated with certain processes, such as, particularly,
petroleum refining. The mixtures of olefins produced possess compositions
varying very widely according to the process concerned.
In the course of the development of the chemical industry based on
mono-olefins, the necessity has arisen of specifically obtaining olefins —
especially ethylene — independently of processes yielding olefins as unavoid-
able by-products.
The demand for ethylene is increasing more and more, while, because of
process changes, refinery gases contain less ethylene, so that the expense
of isolating ethylene is becoming greater and greater. Olefins are found in
high concentrations essentially only in gas-phase cracking processes, in-
cluding catalytic cracking processes, while smaller amounts arise during
mixed-phase thermal cracking.
In the course of time, however, the requirements for unsaturated C and C
3 4
hydrocarbons, especially the C olefins, have increased, because of the manu-
4
facture of highly knock-resistant carburettor fuels and, lately, the production
of butadiene. The scarcity of gaseous olefins capable of simple and economic
isolation finally compelled their production to be expanded in a different
manner.
Starting from the gaseous paraffinic hydrocarbons present in large amounts
in refinery and natural gases, this problem was solved in two different ways —
namely, by the cracking and by the dehydrogenation of these gaseous
paraffins.
By the cracking of gaseous paraffinic hydrocarbons — also called gas
cracking — is understood the pyrolytic decomposition of the normally
gaseous paraffinic hydrocarbons and olefins, such as propane and butane
and propene and butene, to give low-molecular-weight olefins. This process
is used mainly for the manufacture of ethylene from propane or of ethylene
and propene from butane. By rapid heating to 700—800°C (when hydro-
carbons are heated above 600°, one generally speaks of pyrolysis), propane
is substantially decomposed into ethylene and methane. At the same time,
dehydrogenation with the formation of propene takes place, so that the end-
product consists mainly of a mixture of ethylene, propene, methane, and
hydrogen.
Ethane alone decomposes on heating to a high temperature with a short
residence time into ethylene and hydrogen — i.e. it undergoes thermal
dehydrogenation without substantial C—C rupture. In the technical jargon,
not very appropriately, this reaction is described as cracking and the process
is called ethane cracking. In our discussions, however, we will give the name
cracking processes only to those processes in which the rupture of a C—C
bond takes place, while the rupture of a C—H bond will be called dehydro-
genation. When butane is heated to a high temperature, cracking to ethylene
MONO-OLEFINS NECESSARILY ARISING IN VARIOUS PROCESSES 3
and ethane or to propene and methane takes place. In contrast to the analogous
reaction with propene, dehydrogenation of the butane to the butènes takes
place only to a much smaller extent. The higher the number of carbon
atoms of the hydrocarbon concerned, the more readily does cracking take
place and the further does the dehydrogenation reaction recede into the
background.
Up to pentane, dehydrogenation becomes the main reaction if the paraffinic
hydrocarbon is heated quickly in the presence of suitable catalysts to a tem-
perature below that used in gas cracking. This catalytic dehydrogenation
of the paraffinic hydrocarbons has acquired a rapidly increasing importance
during the last 15 years and has made the paraffinic C and, particularly,
3
C fraction of natural gas, refinery gases, and off-gase s of the coal hydro-
4
génation process available to chemical industry based on olefins, decisively
broadening the possibility of utilizing the paraffins for this section of chemical
industry (e.g. rubber synthesis).
In the course of later discussions of the possibilities of utilizing olefins,
which can only deal with the most important processes, it will be shown
that the scope of their reactions is substantially greater than for the paraffins.
The conversion of ethylene, the most important representative of the gaseous
olefins, alone leads to more than 250 products of large-scale manufacture,
of which some are marketed in considerable amounts as intermediate and
finished products — for example, ethanol and its conversion products, ethyl-
ene oxide and its derivatives (particularly glycols and polyglycols), ethanol-
amine, ethoxylation products, and acrylonitrile, and also styrene via ethyl-
benzene, vinyl chloride via dichloroethane, synthetic lubricating oils, plastics
(particularly polyethylene), highly knock-resistant carburettor fuels, etc.
The demand for the lower, normally gaseous, olefins has risen markedly
during the last 20 years. When it is considered that the demand for ethylene
in the U.S.A. was about 680,000 tons in 1950 while at the end of 1962 it
had risen to 2-8 million tons, the assumption that a production of about
3·6 million tons was required in 1967 would seem to be very probable [1],
American forecasts show that even in 1952 it was expected that six times
as much ethylene would be required in 1975 as in 1950. Table 1 gives the
forecasts of the requirements for ethylene, propene, and butene in the U.S.A.
in 1975.
The production of aliphatic compounds from olefins has also increased to
an extraordinary extent in Europe, and many firms that cannot obtain the
chemical raw materials from an adjacent refinery or from natural gas plants
are engaged in it. Such factories obtain their starting materials in their own
plants from materials easily transported great distances in the form of petro-
leum fractions — in the first place, heavy gasoline or gas-oil. More and more
frequently, petroleum oils and their fractions are being treated to give
gaseous olefins particularly ethybne by various processes such as the Ugite
process, the Catarol process, the T.P.C, process, the KELLOGG process, the
SHELL process, and the HOECHST coker process. In these, hydrocarbon
fractions — generally heavy gasoline or fractions boiling in the middle oil
1*
4 MONO-OLEFINS, CHEMISTRY AND TECHNOLOGY
range — are heated to high temperatures for a short time. This gives rela-
tively large amounts of gaseous olefins with a high content of ethylene,
while the liquid fractions from the pyrolysis process contain aromatic
hydrocarbons which in processed form are capable of use as anti-knock
additives for carburettor fuels. The isolation of the aromatics from such
mixtures of hydrocarbons is, unfortunately, expensive. Consequently,
in association with the manufacture of olefins, the pyrolysis process has
been modified in such a way that the liquid reaction products contain about
90-95% of aromatics. This process modification, it is true, leads to a certain
decrease in the yield of olefins in favour of the formation of increased
TABLE 1. Forecast Demand for Gaseous Mono-olefins in the
U.S.A. in 1975 (in tons) [la]
Demand forecast Amounts available
Olefin
for 1975 forecast for 1975
Ethylene 4,750,000 15,500,000
Propene 1,700,000 19,300,000
Butènes 2,300,000 24,000,000
amounts of hydrogen and methane ; however, the aromatics can consequently
be obtained in pure form. In this way additional amounts of a series of
those aromatic hydrocarbons can be obtained for which, up to about 25 years
ago, the only source was coal tar. This additional source of aromatic hydro-
carbons is highly desirable in countries with little petroleum and no catalytic
reforming processes, since the production of coal tar is determined by the
capacity of coking and gas-producing plants, the output of which in recent
years has not risen to the same extent as the requirements of the chemical
industry.
In complete contrast to the cracking processes, pyrolysis processes are
operated solely to obtain starting materials for industry. Thus conditions
are maintained in these processes which lead to the highest possible yields
of olefins. Since pyrolysis is carried out without the use of pressure, in many
cases in the presence of steam, processes are available which are analogous
to the gas-phase cracking processes but are operated at higher temperatures
and with different residence times. The technical arrangement of the plants
is also somewhat altered.
After this general review of the over-all situation in the field of lower
olefins, we shall mention the sources in which these materials are present
in the preformed state and arise unavoidably in the course of the manufacture
of carburettor fuels. Then the processes which give additional olefins directly
will be described. These processes give a desired olefin with good yield,
so that, under suitable conditions, a very expensive process of isolation from
a fortuitously produced mixture of gaseous aliphatic hydrocarbons, usually of
very complex composition, is not necessary.
MONO-OLEFINS NECESSARILY ARISING IN VARIOUS PROCESSES 5
The lower, normally gaseous, or low-boiling, olefins can be obtained:
(A) By isolation from mixtures of gas- (B) By processes permitting the manu-
eous paraffins and olefins produced facture of gaseous olefins for their
as unavoidable by-products. These own sake. These can be divided
are present : in summary fashion into:
1. In refinery gases, such as crack- 1. The dehydrogenation of gaseous
ing gases, gases from thermal paraffinic hydrocarbons
reforming processes, and other (a) Catalytic dehydrogenation
thermal or catalytic processes (b) Thermal dehydrogenation
carried out for the manufacture 2. The pyrolysis of lower and higher
of carburettor fuels. hydrocarbons
2. In the gaseous reaction products (a) Pyrolysis of gaseous paraf-
of the FISCHER-TROPSCH synthe- finic hydrocarbons (gas crack-
sis using cobalt and iron catalysts ing)
(b) Pyrolysis of higher hydro-
3. In the gaseous products of plants
carbons (particularly petro-
for the coking and low-tem-
leum fractions) with the
perature carbonization of coal
simultaneous formation of
and lignite.
a greater or smaller amount
of aromatic-rich hydrocar-
bons (oil-gas process, Ugite
process, Catarol process,
T.P.C, process, etc.).
3. The dehydration of lower alco-
hols, such as ethanol, propanol,
the butanols, and the amyl
alcohols.
In addition, for some olefins, particularly for ethylene, various special
methods of manufacture are available. Because of the importance of olefins
as raw materials for industry, the most important sources of the indivi-
dual lower representatives will be mentioned in this connection:
I. ETHYLENE
(a) In Gases Produced as Unavoidable By-products
1. Refinery gases
2. Coke-oven gases
3. Gaseous reaction products from the FISCHER-TROPSCH synthesis with
iron catalysts
4. Gases from the manufacture of acetylene by the pyrolysis of hydro-
carbons
(b) Additional Direct Manufacture
1. By cracking, e.g., propane (gas cracking)
2. By dehydrogenating ethane or natural or refinery gases or gases
from the hydrogénation of coal
(α) Autothermal dehydrogenation
(β) Thermal dehydrogenation
β MONO-OLEFINS, CHEMISTRY AND TECHNOLOGY
3. By the pyrolysis of petroleum and its fractions
4. By the partial hydrogénation of acetylene
5. By the dehydration of ethanol
II. PROPENE
(a) In Oases Arising as Unavoidable By-products
1. Refinery gases
2. Gaseous reaction products of the FISCHER-TROPSCH synthesis with
cobalt and iron catalysts
3. Products of the gas-cracking of propane for the manufacture of
ethylene
(b) Additional Direct Methods of Manufacture
1. By cracking butane (gas cracking)
2. By the catalytic dehydrogenation of propane from natural gas and
refinery or coal-hydrogenation gases
3. By the pyrolysis of petroleum and its fractions
4. By the dehydration of n-propanol or isopropanol
III. BUTENE
(a) In Gases Produced as Unavoidable By-products
1. Refinery gases
2. Gaseous reaction products of the FISCHER-TROPSCH synthesis with
iron and cobalt catalysts
(b) Additional Direct Methods of Manufacture
1. By the catalytic dehydrogenation of η-butane or isobutane from
natural or refinery gases or the gaseous reaction products from the
hydrogénation of coal
2. By the pyrolysis of petroleum and its fractions
3. By the dehydration of n-butanol or isobutanol
IV. PENTENE
(a) In Unavoidable By-products
1. Low-boiling constituents of thermal cracking or reforming gasoline
2. Low-boiling products from the FISCHER-TROPSCH synthesis with cobalt
and iron catalysts
(b) Additional Direct Methods of Manufacture
1. By the dehydrogenation of pentanes from natural gasoline, straight-
run gasoline, or FISCHER-TROPSCH gasoline
2. By the cracking of hexane under definite conditions
3. By the chlorinating dehydrogenation of pentanes
4. By the dehydrogenation of fermentation amyl alcohol.
MONO-OLEFINS NECESSARILY ARISING IN VARIOUS PROCESSES 7
ΙΠ. THE GASEOUS MONO-OLEFINS
A. REFINERY GASES
The refinery gases arising in the processes carried out for converting crude
oil to products ready for use, which includes all the gaseous hydrocarbons,
have roughly the same importance as raw materials for the aliphatic chemical
industry as coal tar has for aromatic chemicals production. The olefinic
fraction arises mainly by cracking and reforming processes in the course
of the preparation of more and better gasoline than can, in general, be
obtained from petroleum directly.
Refinery gases have compositions differing very widely according to the
method of working of the plant. Formerly, these gases consisted almost
exclusively of the gaseous hydrocarbons dissolved in the crude oil and
liberated by distillation during the processing of the oil. The amount of
these gases varies markedly and depends on the treatment which the crude
oil has undergone from transport to distillation. These olefin-free gases are
more valuable than natural gas, since they are substantially richer in higher
constituents, such as propane and butane, which are more readily soluble
in petroleum than methane and ethane.
Quantitative information in this field is extremely unreliable. Never-
theless, it is assumed at the present time that only one third to one fourth of
the refinery gases arises from the natural gas dissolved in the crude oil.
The distillation off-gases of refineries have in fact been continuously increased
in amount since 1912 by the addition of cracked gases which contain
appreciable amounts of olefins, in addition to paraffins, and generally exceed
the amount of distillation gases.
Because of the enormous increase in the amounts of gas, it was first
necessary for safety's sake to give them some attention, and they were
used for heating purposes. The true chemical utilization of these gases
was begun only in about 1921 in the U.S.A. by two firms — namely, the
CARBIDE AND CARBON CHEMICALS CORP., which was not itself a petroleum
processer, and the STANDARD OIL DEVELOPMENT Co.
Besides the cracked gases, reformed gases are produced in the course of
the improvement of the anti-knock properties of the straight-run gasoline.
The process during which these gases arise will be outlined in an independent
chapter dealing with the manufacture of high-efficiency carburettor fuels.
The mixtures of gases containing olefins and paraffins which arise in these
processes can also be interacted (see Chapter V). Here — so far as this
is possible at all — typical analyses of cracked and reformed gases will be
given.
In this connection, it must be stressed particularly that considerable
variations can arise according to the origin of the starting material for the
cracking process and, in particular, according to the conditions of treatment
or the manner in which the cracked gases are vented. A typical composition
of a refinery gas in molar percentages given by CURTIS [2] is shown in Table 2 :