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ADVANCES IN HYDROFZNING OF BY-PRODUCT GASOLINES FROM
THERMAL CRACKING IN ETHYLENE/PROPYLENE MANUFACTURE
Abstract

Résumé

I n the last fifteen years, by-product gasolines proA u cours des quinze dernières années, les essences
duced by thermal cracking to make light olefins have apparaissant comme sous-produits de la fabrication
been an attractive source of aromatics and high octane parcraquage thermique des oléfines légères ont été une
number motor fuel. For motor fuel production, only source intéressante d’aromatiques et de carburants à
the contained diolefins need be hydrogenated, When haut indice d’octane. Pour la production des carburants,
aromatics are the desired product, complete desulfuriz- il suffit d’hydrogéner les dioléfines. Pour obtenir les
ation, denitrificationand olefin saturation are re- aromatiques il faut en outre réaliser une désulfuration,
quired, generally necessitating at least two stages. The une dénitrification et la saturation des oléfines ce qui
contained diolefins are hydrogenated in the first stage demande généralement deux phases de traitement.
so that the material may be further heated and com- La première phase consiste à hydrogénerles dioléfines
pletely hydrotreated in following stages.
et préparer les phases suivantes ou la charge est portée à
Recent developments, both engineering and cata- température plus élevée et soumise à une hydrogénation
lytic, have brought changes in processing technology complète. On expose les progrès de la technologie de
which will be discussed.
fabrication résultants des derniersdéveloppements à
l a fois dans le domaine des méthodes d’application et en
matière de catalyseurs.

INTRODUCTION

TABLE I

ETHYLENE CAPACITY

The production of ethylene has experienced a n
BiIlions pounds per year f rom:
enormous growth during the past 15 years. In billions
Ethane-propane* Naphtha
of pounds per year, ethylene production outside the
1950
1.5
East-Bloc countries hasincreased from 1 .5 i n 1950 to 1956 3.0
3-0 i n 1956l and to 12 in 1965;present predictions are 1965 UnitedStates
.. ..
6.95
1.60
Europe
0.13
2-01
29 billion pounds by 197019.These values are shown in
0.10
0.21
North and South Ärnerica
Table I. In the United States the principal charge stocks
East and Far East
..
0.01
1.05
__
are ethane and propane while outside the U.S. the usualTotal
.. . . ..
7.19
4.87
charge stock is naphtha. In addition to ethylene, many
1970 Estimates
by-products are formed. Some typical pyrolysis
United States
.. ..
14.52
4.97
products and yields are shown in Table I120.
0.19
5.80
Europe
0.28
0.48
North and South Ämerica
Ethane gives the highest yield of ethylene (82 % wt)
0.05
3.03
..
East and Far East
and the lowest yield ofby-product gasoline (2% wt).
Propane gives an intermediate yield of ethylene (44%
Total
.. . . . . 15.04
14.28
wt) and five times as much gasoline as does ethane.
* Includes recovery from refinery cracked gases.
Yields from naphtha depend upon the paraffin, naphthene and aromatic contents, as well as severity of cracking, but yields from a typical naphtha are 32% wt ethylene yields frompropane and naphtha is almost
ethylene and 22 % wt by-product gasoline. On a billion compensated for by the difference in specific gravities
pound of ethylene per year basis, 35,000 bd of propane of these two feedstocks.
In the compilation of ethylene plants by Burke and
or 32,800 bd of naphtha are required. The difference in
Miller19, charge stocks were given as ethane-propane
or naphtha.Assuming that the ethane and propane
were employed in equal quantities, the amount of
b y CHARLES H. WATKINS,
Universal Oil Products Company, Des Plaines,
pyrolysis gasoline produced outside the East-Bloc
countries amounted to 43,000 bd in 1965 and will
Illinois, U .S .A .

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Hydrotreating

COMPOSITION OF BY-PRODUCT
PYROLYSIS GASOLINE

probably amount to 119,000 b d by 1970. A...