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Патент USA US2398846

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April 23, 1946.
Filed July 6, 1944 ‘
‘Juan!‘ ’
VS.8uobaimw w
John C. mundaz/ _ Unverzbcr
.o ‘n e u‘
. Patented Apr. 23. 1946 ,
. John C. Munday,
Cranford, ‘N. J., assignor to
Standard Oil Development Company, a corpo
ration of Delaware
Application July 6, 1944, Serial No. 543,626
5 Claims.
The present invention relates to an improved
process for the production of gasoline and other
light hydrocarbons from heavier hydrocarbon oils
(or. 196-52)
gasoline so as to renderit more suitable for retreatment in a cracking zone.
A secondary object of my invention is to im
gasoline fractions and the cycle oil in the
The catalytic cracking of hydrocarbon oils,
of a fraction boiling between the gaso
, such as gas oil, to form cracked gasoline has now
line and the initial feed stock in order to im:
become common practice in the petroleum re?n
prove the economics of the overall process, in
ing industry, While the raw cracked gasoline
particular to effect the saving in hydrogen which
has, of course, many advantages over the gaso
one of the materials I employ in my process.
line produced by the older thermal cracking 10 A
third object of the present invention is to
methods, nevertheless it has to‘undergo consid
improve the quality of both the gasoline and the
erable after-treatment and/or re?ning in order
cycle oil recovered from a catalytic cracking op
‘ to produce ?nally a satisfactory commercial.
eration in a more expeditious and economical
product. In general, there are two main consid
than has been possible heretofore.
erations presented to the re?nery in after-treat 15' ‘manner
Other and further objects of the present in
ing or handling the material recovered from a
vention will appear from the following more de
cracking reactor or zone. In the ?rst place, the
tailed description and claims.
raw product is not 100. per cent gasoline and con
In the accompanying drawing, I have shown
tains sustantial quantities of unconverted ‘gas oil
diagrammatically merely the essential apparatus
or heavier ends which, during cracking, have un '20 of a unit in which a preferred modi?cation of
dergone some change which makes them less de
my invention may be carried into practical effect,
sirable for recracking than the original feed f with
only so much of the accessory apparatus as
stock. Thus the unconverted gas oil commonly
is necessary to aii‘ord a clear understanding of
called “cycle oil," since it is returned or recy~
the invention.
cled in whole or in part to the cracking zone,
a gas oil,‘
acquires as a result of the operation high mo
which may be a West Texas crude oil boiling in
lecular-weight aromatics containing two or more
the range of from 500° F. to 800° F. and having
benzene rings in a condensed nucleus. The pres
an A. P. I. gravity of about 30, is introduced into
ence of these aromatics is detrimental to the op
the system through line I, thence heated in a
by‘ catalytic cracking. .
eration of cracking, since they decompose during 30 ?red coil 3, or other suitable means, to a tem
the cracking or‘recracking to .form unduly large
perature of, say, 900° F., whereupon it is With
quantities of so-called coke, a carbonaceous de- ,
posit which forms on. the catalyst. Consequently,
'it is desirable to treat this cycle oil to improve
its qualities before it is again- subjected to
With‘respect to the gasoline itself, particular
ly where the object of the process is to produce
aviation gasoline, the same invariably contains
substantial quantities of normally liquid ole?nic
hydrocarbons which .are undesirable particularly
when the gasoline is eventually to be blended
.with lead tetraethyl, since such an ole?n-con
taining gasoline is less responsive to octane num
' drawn through line 5 and discharged into a crack
ing vessel l0 containing a catalyst C. The pres
sure employed in_ the cracking operation may be
atmospheric or thereabouts, for example in the
range 0 to 100 lbs. per square inch gauge. The
catalyst may be a natural or acid-treated ben
tonitic clay, or a synthetic gel of silica and alu- ‘
mina. In the modi?cation of my invention which
I have shown to illustrate my invention, the crack
ing is carried out in a stationary bed type of cata~
lyst contained in a cylindrical or other suitable -
case l0. Since cokeis formed on the catalyst dur
ing cracking, ‘it is generally desirable to provide
ber improvement by‘the addition of lead tetra 45 more than one catalyst case so that by proper al
ethyl than a, saturated material would be. In
other words, such a gasoline fraction is said to
have a lower lead susceptibility (a technical term
in this particular art) having the signi?cance
The main object of the present invention is to
improve the normally liquid cracked portions of .
a cracked gasoline and, at the same time, to im
prove the so-called cycle oil or that portion of
the original feed stock which is not converted to
ternation the oil‘?ow can be made continuous
even while coke is being removed by periodic burn
ing with air. It should be appreciated that I may
carry out my process of cracking in any, of the
known methods; such as the so-called ?uid cata
lyst type of operation where the catalyst in pow
dered condition is passed through a so-called de
layed settler type of reaction and regeneration
zones, in the form of a ?uidized mass of catalyst
admixed with reaction and regeneration vapors,
or I may use‘ other known types of operation
on a suitable spacing agent or carrier such as
~ where the catalyst in the form of grains, granules?
lumps. and the like, moves by gravity or forced
circulation through a reaction zone and a regen
and the like. Very good catalysts for the purpose
crackedproduct rather than in a speci?c type of
intended are synthetic chromium-aluminum
oxide‘gel containing about 35 per cent chromium
oxide, and activated aluminum oxide impregnated‘
with 5-20 per cent of molybdenum oxide, The
cracking, it will not be necessary to describe in
catalysts may be regenerated by passing, air or
detail the cracking process. ‘
air diluted with nitrogen or flue gas over the
eration zone. However, since the gist of my in
vention resides in thesubsequent treatment of the
activated aluminum oxide,'bauxite, silica gel, clay,
Cracked products from the illustration I have 10 catalyst until‘ the coke content is reduced to the
desired extent, taking care that high temperature
shown are withdrawn ‘from the reactor through
does not deactivate the catalyst. The oxidized
a line l2 and immediately discharged into a frac
catalyst maybe treated with hydrogen before
tional distillation zone M where the crude
placing it back on stream, if desired.
cracked products are fractionated into the fol
lowing fractions: First, there is taken overhead 15 The treated materials are withdrawn from
hydrogenator 40 through line 80, thence dis
through line It that portion of the total product
charged into a hydrogen separator 62 from which
the hydrogen may be withdrawn through line 55
and recycled to line 50 for further use in the
cooler l6 into separator ll; light gases are re
moved overhead from the separator through line 20 process. It may be and often is desirable to pass
the hydrogen-containing gas in line 50 through
It and liquid hydrocarbons, including C4 and
a scrubber where it contacts in countercurrent
some C3, are removed through line I9 and may
?ow an absorption oil, such as, say, a light naph
be utilized in alkylation and polymerization proc
tha which scrubs out and/or dissolves light hy
esses. A second fraction comprising the CIR-325°
F. hydrocarbons is withdrawn through line 22, 25 drocarbons thereby enriching the ra?inate in
hydrogen content. The bottoms withdrawn
and acycle oil fraction boiling above about 500°
from separator 62 through line 10 carrying a
F. or 550° F. is withdrawn through line 24, These
pressure reducing valve 13 are then discharged
two fractions are combined and it is with, respect
which includes the lighter fractions up to the C5
hydr0carbons.- This material is passed through
into a fractionator 15 from which the now satu
to the re?ning of these particular said fractions
that my invention is principally concerned. In 30 rated Cs-325°,F. gasoline fraction is withdrawn
through line 80 and delivered to storage drum 8!.
treating these fractions, I ?rst pass them by
means of a pump (not shown) through line 22
and through a heating means, such as ?red coil
30, and thence through line 32 and then into a
. The bottoms from fractionator ‘I5 are withdrawn
drogen from some source is passed from line 50
inlet line I for further treatment in the cracker
i0. The normally gaseous hydrocarbons and pos
through line 83, and this material which is the
cycle oil previously mentioned, improved as'to
hydrogenation reactor 40. Simultaneously, hy-. 35 its cracking properties, is discharged into feed
through a suitable heating means 55, which may .
sibly some hydrogen which are contained in the
be a?red coil,‘ and thence discharged via line 56
crude product withdrawnv from 40 are withdrawn
into line 32 where it admixes with the heated
hydrocarbons and is discharged with the latter 40 overhead from fractionator 15 through line 90
and these may be disposed of in any convenient
into the'hydrogenation reactor 40. The hydro
gen employed is preferably that produced in the
cracking step, separated from cracked products
in separator i1 and passed through line l8 into
line 50.
,Of course, it will be understood that the raw
gasoline collected in storage 8| may be corrected
as to volatility by the additionof suitable blend
ing agents thereto, or bythe removal of light ends
In the hydrogenation reactor, the desired re
sult is to saturate the ole?ns in the (Is-325° F.
and of course may be blended with up to 4 cc. of
benzene rings in a condensed nucleus, which are
about 500° F. or 550° F., and in a preferred opera
lead tetraethyl per gallon of gasoline according
fraction of the gasoline withdrawn from fraction
_ to standard practice.
ating column I4, and at the same time to hydro
genate the aromatics, particularly the high mo 50 The cycle oil fraction which is subjected to mild
hydrogenation has an initial boiling point above
lecular weight aromatics having two or more
tion has a boiling range similar‘to that of the
contained in the heavy bottoms withdrawn from
fresh feedstock. If the aviation gasoline fraction,
fractionating column 14 through line 24. To ac
complish this end, I maintain the following con 55 which is hydrogenated along with the cycle oil,
boils up to 325° F. as mentioned above, it will
' ditions in hydrogenator 40:
Temperature ____________ __. 600° F. to 800° F.
Pressure___-_-____-_.._____. 200 lbs. to 3000 lbs.
. -
per sq. in. gauge
Oil feed rate _____________ _. 1 to 5 v./v./hr.
Hydrogen, cu. ft.
per barrel feed _________ _. 1000 to 6000
Under the conditions I have set forth in the
preceding table, I accomplish the saturation of
the ole?ns and at the sametime convert a sub
stantial part of the heavy aromatics in the cycle
stock by hydrogenation into naphthenes which
contain the Ca aromatics, the xylenes and ethyl
‘benzene. In some cases, for example when the
capacity of the hydrogenation unit or the amount
60 of hydrogen available is limited, it may be desir
able to bypass the C8 aromatic fraction boiling
between 265° F. and 325". F. around the hydro
genation step, by passing it from fractionator I4
‘ through line 82 to line 80 and thence to storage
If the toluene concentration is high,
65 drum 8|.
it may be desirable to bypass the 221° F.-325° F.
fraction through line 82.
An intermediate fraction boiling between the
cycle oil and the aviation gasoline, in example
are more suitable as a catalytic cracking stock
than the said aromatics for the reasons herein 70 between 325° F. and 550° F., is withdrawn from
fractionator l4 and is rejected from the system,
before stated’. As to the catalyst, I prefer to use
whereas by mild hydrogenation the aviation gas
a regenerable catalyst. Included in such a group
oline is improved in quality and the cycle oil is
, are group VI and VIII metals and metallic oxides,
made more amenable toward cracking to high
such as nickel or molybdenum oxide or chromium
oxide. The catalyst is‘ also preferably supported 75 quality gasoline. Hydrogenation of the interme
diate fraction is imdesirable since its quality as a - oil feed, while increasing coke formation from 4.2
motor fuel is degraded by hydrogenation, and its . to only 5.0 weight per cent based on feed. .
value as a cracking stock even after hydrogenation
Numerous modifications of my invention fail
is far less than that of cycle oil or fresh feed. Re
' ing within'the scope thereof may be made by
jection of the intermediate fraction therefore has
the eii‘ect of increasing the overall quality of the
aviation gasoline produced and of plant capacity,
'those familiar with this art.
and also of keeping hydrogen consumption in line
with hydrogen production in the cracking step.
Hydrogen consumption may also be decreased
by bypassing the Ca fraction of the cracked prod
ucts around the hydrogenation zone, by passing
it from fractionator ll through lines 84 and 80
catalytically cracked gas oil. the improvement
which comprises withdrawing ‘the products from
a catalytic cracking zone, fractionally distilling
the ‘same into ‘a fraction consisting of- C5 hydro
into storage drum 8 I .
What I claim is: ' 4
1. In the re?ning of the total products of a I
carbons to those boiling up to about 325° F. and
a second fraction comprising the hydrocarbons
1 boiling above about 500° R, combining the segre
For example, a Southwest Louisiana wide-cut 15 gated fractions, subjecting the, combined frac
gas oil having an A. P. I. gravity of 32°, an aniline
tions to a mild catalytic hydrogenation in the
point of 1'75, and a boiling range correspondingto
presence of added hydrogen wherein the oleiins
5 per cent at 484°, 50 per cent at 622°, and an end
are saturated and‘the aromatics in the fraction
point of 700° F’. is cracked at 975° F. employing a
boiling above about 500° F.‘ are substantially con
powdered silica-alumina catalyst in 13:1 catalyst 20 verted to naphthenes, in a hydrogenation zone,
to oil weight ratio and a weight-space velocity of
withdrawing the hydrogenated products from the ,.
4. On a volume per cent fresh feed basis, there
zone, fractionally distilling the hy
are obtained 28 per cent aviation gasoline of 7
drogenated products to recover ‘a saturated avia
lbs. vapor pressure which has an acid heat of
tion gasoline boiling up to 325° F., separately r'e
a 141° E, a bromine number of 74, and ‘a boiling 25 coveringa fraction boiling above 500° F., and re
range of 110° F. to 332° F., and 26 per cent cycle
cycling'the last-named fraction to the cracking
oil boiling above 500° F. The intermediate frac
tion which has a low octane number (65-70 C. F.
‘ 2. The method of claim 1 in which the hydro
R. Motor method) is rejected from the process.
genation is carried out in the presence of a re
The aviation gasoline is fractionated into a 30 generable catalyst.
light fraction and a heavier fraction boiling above
3. In the production of high quality aviation
221° F. which contains xylenes and a small
gasoline,the steps of catalytically cracking a gas
amount of toluene. The heavier fraction is by
in a cracking zone, withdrawing the cracked
passed around the hydrogenation step. The light
products and fractionally distilling the same into
' aviation fraction-and the cycle oil fraction are 35 non-aromatic and aromatic fractions boiling in
, combined and are hydrogenated at 730° F., 3000 the aviation gasoline range, and a heavy cycle oil
' ‘lbs. per square inch pressure, 6000 cubic feet of
' hydrogen per barrel, and 1.0 v/v./hr. space
velocity, employing tungsten sul?de catalyst.
The hydrogenation product is fractionated, the
light fraction is combined with the bypassed aro
matic fraction, and the heavier hydrogenated
fraction is recycled to the cracking step. The
combined fractions comprise an aviation gasoline -
having an aviation octane number of 96.5 by the
AFB-1C method as compared to 92 for the orig
inal cracked aviation gasoline, each being tested
at '7 lbs. vapor pressure with 4 cc. lead tetraethyl
per gallon.
fraction, combining the non-aromatic aviation
gasoline fraction with the said heavy cycle oil
fraction, subjecting the mixture to a mild cata
. lytic hydrogenation, separating the hydrogenated
products into an aviation gasoline fraction and a
cycle oil fraction, combining the hydrogenated
aviation gasoline fraction with said aromatic
fraction to form ‘aviation gasoline, and recycling
the hydrogenated cycle oil to the catalytic crack
ing zone.
4. The method of claim 3 in which the hydro
genation catalyst is of the regenerable type. t
5. The method of claim 3 in which the heavy,
Recycle of the heavy hydrogenated cycle oil to 50 recycle
oil boils above about 500° F.
the cracking stepincreases the yield of aviation
gasoline from 28 to 37.3 per cent based on gas ’
Joan c. MUNDAY.
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