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Патент USA US2403869

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Patented July A9,
Y '
VRoberti?. Marschner, Homewood,l Ill., assignor ` `
toStandard Oil >CompanmnChicago, Ill., a cor,
V poration of ,Indiana`
Application April 29, 1942, Serial No- 440,989
solaires. y(c1. '26o-6831>'
This invention relates to aviation gasoline pro
duction and it pertains more` particularly to im
proved methods and means for processing amix
ture'of hydrocarbon gases containing normal bu
tane, isobutane, propane, butene-Ãbutene-l, iso
carbon mixtures with which such isooctanes can
beblendedhave either too low‘an octane number
or too high a’vapor «pressure or both for aviation
gasoline. An object of my invention is to decreasey
> the amountgof Cri-C6 -hydrocarbons requiredfor
the blending- with isooctanesv and to provide a C'r
hydrocarbon blending stock for simultaneously
Heretofore refinery gas streams containingvCa
providing optimum volatility and maximum oc
and C4, oleñnic. hydrocarbons have been thermally
tane number. A further object is to increase the
or catalytically polymerized to produce “non
selective” polymers (chiefly dimers and trimers 10 yield of avia-tion gasoline'y per unit lof, C4 oleflns
with more or less intermediate and heavier prod
The Ca-Ci refinery streams which contain iso
ucts) which are characterized bya relatively wide
butane as well as oleiins have been charged‘to an
and rather high boiling-range and an octane num.- ~
alkylation4 process for the direct production o_f
ber in_the general vicinity of r15430. 'Such polymer
is suitable for ordinary motor fuel but it is not 15 isoparaiiins of the aviationrgasoline boiling range.
butylene and propylene.
suitable, because oi its highunsaturation, for
aviation gasoline. On hydrogenationito `remove
the unsaturation the octane number of such “non
In, alkylation processesl the propylene-isobutane
alkylate has*` a much lowerA octane number vand
consumes much greater >quantities Vof, catalyst
selective” polymer is not improved to any appre
than the butene-isobutane. alkylate.` Further
lowered. When the charge contains large
amounts of propylene and only small amounts of
lower octane number than the'normal butene
` isobutane alkylate rand generally speaking the
about 80 but which upon hydrogenation give par
aflins havingan _octane number of only about
60-70. Hydrogenated non-selective lpolymer is,
therefore, unsuitable for aviation gasoline not
It has, therefore, 'been proposed to subject a nor
ciable extent and 1in some cases itis actually 20 morer `,the isobutylene-isobutane alkylate has» a
presence of isobutylene 'in the alkylation charge
butylenes there is a tendency toward the Ápro
results in greater acid.> (catalyst) requirements
duction of the propylene trimer,'a mixture 'of C9
oleñns which have an >average octane number yof 25 and less desirable yields -and product distribution.
only because of its volatility `characteristics but
because of the low octane number of the hydro
genated polymers. Since both low volatility and
low octane number appear to be associated with
propylene, thisf'oleñn is customarily considered
worthless as a raw material for aviation gaso
line. An object of my invention is to provide an
improved. method and means for producing a
hydrogenated copolymer of about C6 toCs (chief
mal butene-isobutylene mixture ñrst to selective
polymerization for utilizing the isobutylene com-f
ponent and then to alkylate the remaining bu
tenes with isobutane.
In such processes a con’
siderable amount of the butene-2 is used up in
the .polymerization step and 'is hence unavailable
for alkylation. Here again the propylene con
tent of the charging stock is not utilized. An
important object ofA my invention is to utilize the
propylene and isobutylene ,content 0f the charg
ing .stock most effectively in a polymerization
step andto conserve the butene-2 component of`>
the charge for subsequent alkylation with iso
ly Cv) boiling range which is characterized by
40 butane.
a high octane number.
A further object of my invention is .to provide
Selective polymerization of butenes results in
"a unitary system oi polymerization, fractiona
a dimer or codimer having an voctane number
tion and hydrogenation which may be supple
of approximately 82 to 84 and on hydrogenation
the hydrodimer or hydrocodimer has an octane
number of about 92 to 94. The'term hydrodimer
is hereby deiined `to vmean hydrogenated dimer
and the Word hydrocodimer-'is deiined to mean
hydrogenated codimer. In'such a process, how
ever, there is no utilization of the propylene
mented by alkylation -and which may/be further
supplemented by butane isomerization in- order
to produce maximum yields of a superior avia
tion-gasoline. Other objects will be apparent as
the detailed description lof the 'invention pro
my preferred operation I initially fraction
content of the charging stock and two mols of 50 ateInthe
Ca-Cihydrocarbon charging stock mix
C4 oleñn are required to produce one mol of avi
ture between normal butane and butene-l; at at
ation gasoline. Furthermore, the resulting “iso
mospheric pressures> this'would mean fraction'
octane” product is characterized by a vrelatively
ation at about 25° F. The overhead fraction will
narrow boiling range which is higher than that
thus contain propylene (-54° FJ, propane
desired for aviation gasoline. Most light,` hydro
(-44° FJ, isobutane (10.9" FJ, isobutylene (1gb
conjunction with the accompanying drawing
FJ, and butene-1 (20° E). The bottoms frac
tion from this fractionation step Will consist es
sentially of normal butane (31° F.) and butene-2
(34° lik-38° F.). The overhead fraction which
contains the isobutylene and propylene but which
does not contain substantial amounts of butene-2,
is charged to a polymerization step employing
, which forms a part of this specification and which
a catalyst such as copper pyrophosphate, phos
is a schematic flow diagram of my improved sys
tem for convertingv C3-C4 refinery gases into
maximum yields of maximum quality aviation
The charging stock from my system may be
a mixture of gases from any source containing
propylene, iso and normal butenes and isobutane.
phoric acid or any other known polymerization 10 The latter may be obtained by isomerizing normal
catalyst in order to accelerate the polymeriza
butane if it is not present in sufficient amounts
tion reaction. In this step the isobutylene and
in the charging stock. Such a gas mixture is
propylene are utilized to the maximum practi
produced in practically all thermal and catalytic
cable extent for the formation of polymer and
cracking, reforming and gas reversion processes.
the conditions of the polymerization are regulated 15 I prefer a mixture in which the isobutylene con
to produce a maximum of heptenes and a min
tent is approximately as great or greater than
imum of nonenes and heavier hydrocarbons. The
the propylene content but my invention is not
heptene polymer fraction, which may also con
limited to any particular charging stock compo
tain Ce and C8 olefins, is `then separated from the
As a speciñc example of my invention I will
C9 and heavier olefins,'the latter being utilized 20
in -motor gasoline. The heptene polymer frac
describe the use of a gas mixture obtained from
tion is hydrogenated and is thus converted into a
a thermal or catalytic cracking process. The
valuable aviation gasoline fraction.
invention is particularly adaptable to gases pro
The normally gaseous hydrocarbons recovered
duced by catalytic cracking of normally liquid
by debutanization of the polymerization products
hydrocarbons, in which gases isobutane is more
are fractionated to separate propane and any re
abundant and the polymerization step feed there
sidual propylene from isobutane and butene-2.
fore represents a larger proportion` of the total
This fractionation at atmospheric pressure would
gas. 'I'he light products from this thermal or
catalytic process may be passed through a high
be at about 0° F. or lower. The overhead gas
is discarded and the isobutane and butene-2 is 30 pressure separator for the removal of noncon
commingled with the normal butane-butene-2
densible gases such as hydrogen, methane and
fraction from the original fractionation step for
most of the ethane and ethylene. The remaining
alkylation with sulfuric acid or other known al
cracked gasoline plus C3 and C4 hydrocarbons
kylation catalyst. The normal butane from the
may be introduced by line I0 into gasoline sta
alkylation products may be isomerized to isobu
bilizer II. The gasoline fraction may be With
tane and returned to the alkylation step. 'I‘he re
drawn directly through line I2 to motor gasoline
sulting alkylate may then be blended with the hy
storage tank I 3, _
drogenated heptenes for the final aviation gaso
The mixture of C3 and C4 hydrocarbons passes
line blend.
from the top of the stabilizer through line I4 to
By removing the butene-2 from the charge to 40 gas fractionator I5 which may be a single column
the polymerization step I minimize the formation
or a plurality of columns 4for separating hydro
of Ca copolymer and obtain a maximum amount
carbons boiling above about 25° F. from hydro
of C7 hydrocarbons and a product which when
carbons boiling below 25° F. rI'hus fractionating
hydrogenated has a very high antiknock rating.
column I5 may be designed to separate C3 hy
Some of the butene-1 will polymerize with iso
drocarbons from Cl hydrocarbons, the propane
butylene but this polymerization does not pro
and propylene passing overhead through line I6
ceed quite as rapidly or to the same extent as the
and the butanes and butylenes being -withdrawn
corresponding polymerization of isobutylene with
from the bottom through line I1. to a second gas
butene-2 or of isobutylene with propylene. The
fractionating column I 8. If desired, a minor por
butene off-gases from the polymerization step are 50 tion of propane and propylene may be discarded
almost entirely butene-2 (evidently the butene-1
through line IGa in order to maintain the opti
is isomerized to butene-2 in the polymerization
mum propylene to isobutene ratio. The second
step). Some of this butene-l (and its butene-2
gas fractionating column I8 is designed and op
isomer) is used up in the polymerization step but
erated so that isobutane, isobutylene and butene
a substantial amount of the butene-2 is recovered '
1 are taken overhead through line I9 while nor
with the isobutane for alkylation with the bu
mal butane and butene-2 are withdrawn from the
tene-2 which has by-passed the polymerization
base through line 2U.
step. The depropanized off-gas is thus by itself
The'propane and propylene from line I6 to
an almost ideal alkylation feed, containing no
gether with isobutane, isobutylene and butene-1
expensive low-yield, low octane number oleñns 60 from line I9 are introduced through line 2I to
and no diluent n-butane, but in volume it repre
polymerization reactor 22. The polymerization
sents only a portion of the potential raw material
may be effected with a copper pyrophcsphate
for aviation gasoline. Thus by alkylating the
catalyst at a temperature within the approximate
polymerization off-gas and blending the alkylate
range of about 300 to 500° F. for example within
with the approximately equal volume of hydro 65 the general vicinity of about 400° F. under a
genated fractionated codimer ordinarily ob
pressure of about 500 to 1500 pounds per square
tained, a ñnished aviation gasoline results but
inch, for example about 1200 pounds per square
by means of alkylation of the isomerized and al
inch. The flow rate through the reactor will
kylated n-butane-butene-Z cut a much larger
depend on the concentration of the olefins in
amountof high octane number alkylate results,
and even though the blend with the hydrocodimer
no longer passes aviation gasoline volatility spec
ifications, this operation is ordinarily advisable.
the charging stock and will usually range from
approximately 10 to 50 cubic feet per hour (mea:
ured at 60° F. and 1 atmosphere) per pound or"
catalyst in the reactor. The copper pyrophos
phate catalyst may be prepared from stoichio
from the following detailed description read 111 75 metric proportions of reactants to obtain CuzPzOv
The invention will be more clearly understood
¿within the approximate range of 300 to> 3000
orI mayemploy an excess of sodium pyrophos
:phate'or copper sulfate. This catalyst is prefer
pounds or more per square inch, the temperature
may bevwithin the approximate range of 550 to
850° F. and the space velocity may be approxi
mately 1 to 5 volumes of charging stock (liquid
basis) per hour per volume of catalyst space in
the reactor.v Alternatively I may employ a cata
ablyfsupported on a carrier such as highly porous
carbon or other known catalyst support. Where
a phosphoric acid catalyst is employed it is usu
ally supported on kieselguhr and the polymeriza
tion is effected within the approximate tempera
lyst such as copper, cobalt or preferably nickel
. ture range of 300° to 480° F. under a pressure
_or the lower oxides of such metals supported on
within the approximate range of 400 to ‘1.400
pounds Vper square inch. Other solid catalysts
such as “synthetic clays,” and even liquid acid
catalysts, may be employed if the reactioncon
lditions are fmodiñed accordingly. No invention
is claimed in the polymerization step `per se since
the conditions required for various catalysts,
charging stocks, etc., are Well known in the art.
pumiceysilica or the like. If catalysts such as
nicke1 or nickel oxides are employed the hydro
genation may be effected at pressures ranging
from near -atmospheric to about 50 pounds or
more per >square inch, the temperatures may be
within the approximate range of 350 to 450° F.
It should be understood also that the charging
stock to this polymerization step may be desulfur
ized or otherwise pretreated, that a plurality of *Y k
polymerization reactors may be employed in series
or in parallel either concurrently or countercur
rently and that all known expedients may be em
ployed `for the effecting of theV desired polymeriza
tion. For example, the conversion may be >re
land the space velocities of the order’of 2 to 10
lvolumes (liquid basis) of charging stock‘per hour
per Volume of y'catalyst space. No invention is
'claimed in the hydrogenation step per se vand
hydrogenation system ‘29~is intended to include
all known features and expedients which may
be necessary or 'desirable in such system. ~ The
hydrogenated C7 hydrocarbon polymer together
with the Cs and Cs hydrocarbons associated there
with are withdrawn from the hydrogenation sys
duced and the entire off-gas may be recycled
tem through line 30 and introduced into aviation
through the reactor together with fresh feed to
gasoline storage tank 3|.
` K
force the reaction of isobutylene with other ole
' The Vdebutanizer gases from’the top of tower
fins rather than with itself. Similarly, the de
24 are introduced through line 25 to gas frac
propanized overhead may be recycled through
tionation column 32 which is designed'r and 0p'
the polymerization to increase prcduction‘of hep
tenes. The conversion in the polymerization re Y y erated to remove propane, propylene 'and any
lighter gases as an overhead through‘line 33a.
action is preferably Within the range 50 to 75%,
The isobutane and butene-2 is withdrawn from
depending upon the relative amounts of isobu
tylene, butene-l and propylene present. With , the base of fractionator 32 through line 33 and
this stream together with ‘the normal butane
typical thermally cracked gases, the isobutylene
butene-Z stream from line 20 are introduced by
conversion is preferably'above 90% and the pro
line 3i!` toY alkylation system 35. This' alkyla
pylene conversion can be maintained above v80%
tion system may be ofthe sulfuric acid typeV em
without a correspondingly large clean-up of the
ploying inlet acid concentrations of about 96 to
normal butenes.
" '
98%„and outlet titratable acids in therange of
The `polymerization products 'from reactor or
polymerization system 22 are introduced'through
about 88 to l92% or a similar process in which
the acid concentration is maintained constant at
92-94%. Y The acid requirements for this system
are minimized by the elimination of the propylene
and isobutylene from the> charging stock and by
line 23 to debutanizer tower 24 which is designed
and operated so that gases including C3 and C4
hydrocarbons are taken overhead through line
25 andnormallyliduid polymers are removed from
the bottom through line 26. rI‘his polymer irac
tion is usually of relatively wide boiling range
maintaining a relativelyhigh isobutane to bu
tene-2 ratio. The elimination of the isobutylene
and butene-l from the alkylation charging stock
and while it is a very good blending stock for
motor gasoline it is not yet a satisfactory avia
also results in higher yields and products of high
er octane number than would otherwise be ob
tion gasoline. If the» entire copolymer is hydro
genated the resulting octane number is ordinarily
tainable.V The alkylation maybe effected in high
not materially increased. I have discovered how
ever that if the light fraction of this polymer,
consisting essentially of Cra-Cv and some vCa hy
drocarbons, is separated from the C9 and heavier
hydrocarbons, the hydrogenation step will effect
a material increase in the octane number. I
introduce the polymer from line 26 to fractionator
v'2l which is designed and operated to >take over- e
head through line ‘28 the Cs, C7 and C8 polymers,
i. e., all liquids boiling up tol about 200 to 250° F.,
for example up to 230° F.
This light fraction is-then passed to a hydro
' genation system 29 wherein it is hydrogenated
with the aid ofrany known type of hydrogenation
catalyst to eiïect saturation ofthe light ypoly
mers, without material production of lighter hy
drocarbons such as methane or butane. As cata
lyst,.I may use oxides or sulfides of group VI
metals such as molybdenum, chromium, tungsten,
etc., eitheralone or in admixture with each other
or with other metallic oxides, and I may mount
such catalysts on suitable supports such as Acti
vated Alumina', alumina gel, bauxite, etc. With
speed mixers for insuring >intimate contact and
with cooling means for maintaining 'the alkyla
tion temperature within the trange of about 30
to'îO"V F. Approximately 0.3 to' 0.4 volurneìof
fresh acid and about 2.5 to 3l volumes of `re’
cycled acid may be charged to the reactor for
each volume of liquid charging stock introduced y
thereto.- No invention is claimed in the alkylaè
tion step per se sincey the method and ’con
ditions for operating'such processes are well
known to those skilled in the art and alkylation
_,system'35 is intended to‘> include all expedients
known to the art for such operation. My inven
66 tion is not limited to thefuse of a sulfuric acid
alkylation system since other catalysts such as
aluminum chloride, metal oxides, etc. are vwell
known to those` skilled in the art.l
'The alkylation products are introduced by line
36 to debutanizer column 31,'from the base of
which the alkylate is withdrawn through line >38'
and introduced' into aviation gasoline storage
tank 3! . Unreacted gases may be recycled to the
alkylation step. The debutanizer gases leaving
'such catalysts thel operating pressure maybe 75 the top of tower 31/may be introduced through
Aline 39 to a butane isomerization system 40 for
converting normal butane into isobutane and the
resulting isobutane may be returned by line 4|
and line 34 to the alkylation system 35. If de
sired the debutanizer gases from line 39 may first
mer fraction wherein its use is markedly beneñ
cial and I have thereby rendered this speciñc
light fraction of polymer suitable for use in avia
be fractionated so that only the normal butane
fraction is passed to the isomerization system
ment of my invention it should be understood
and the unreacted isobutane is recycled directly
to the alkylation system. The butane isomeri
zation system may employ a catalyst consisting
example or to the recited details of operation
since many alternative and equivalent systems
will be apparent to those skilled in the art from
the above detailed description.
essentially of aluminum chloride distributed on
a porous support of solid inorganic material Which
tion gasoline.
While I have described a particular embodi
that the invention is not limited to- this specific
I claim:
has been partially but not completely dehydrated
1. The method of obtaining maximum utiliza
or on clays of the type employed for the refin
ing of animal, mineral or vegetable oils. Alter
natively, the catalyst may be an aluminum chlo
tion of a hydrocarbon gas stream containing
ride-paraflinic hydrocarbon complex in liquid
form or may be aluminum chloride dissolved in
a diluent or in the liquid charging stock itself.
Hydrogen chloride is usually employed for pro
moting this isomerization reaction and it may
be effected at temperatures ranging from room
temperature to 200 to 300° F. No invention is
claimed in the isomerization step per se, and
since this process- is Well known in the art it
Will not be described in further detail.
The aviation gasoline properties of the blended
gasoline in tank 3! may be adjusted by the addi
tion of other hydrocarbons. Isopentane may be
added to the extent of 5-10% to further increase
°the volatility, the amount necessary to give 7
pounds Ried vapor pressure being only about half
that required by isooctane. The boiling range
may be lowered Without decreasing the octane
number by the addition of up to 40% light paraf
15 propylene, isobutylene, and normal butenes for
the preparation of aviation gasoline which meth
od comprises fractionating said gas stream into
a light fraction containing predominately propyl
ene, butene-l, and isobutylene and a heavy frac
20 tion containing butene-2, polymerizing the light
fraction under conditions for effecting the for
mation of substantial amounts of a heptene frac
tion, hydrogenating said heptenel fraction under
conditions for effecting saturation, alkylating the
25 heavy fraction containing butene-2 with isobu
tane to form alkylate “isooctane” and blend
ing said alkylate “isooctane” with said hydro
genated heptene fraction.
2. The method of claim 1 wherein the light
30 fraction contains isobutane and which includes
the further step of separating a gas fraction
containing isobutane and butene-Z from the
products of the polymerization step and intro
ducing said gas fraction into said alkylation step.
3. The method of claim 1 wherein the heavy
iins such as neohexane or light naphthenes such
fraction contains normal butane which method
as cyclopentane. The volume of aviation gas
includes the further step of isomerizing said nor
oline may be considerably increased at some
mal -b-utane to isobutane and introducing said
expense in octane number by dilution with
isobutane into said aikylation step.
10-40% straight-run naphthas, and may be 40
4. The method of claim 1 which> includes the
greatly increased by blending with nearly an
further step of remo-ving heavy polymers from
equal amount isomate or catalytically cracked
said heptene fraction prior to said hydrogen
naphthas. Isomate is the normally liquid prod
ation step.
uct fraction in the gasoline boiling range result
5. The method of making an aviation gasoline
ing from the isomerization of light naphtha with 45 from a gas stream containing propylene, isobu
an aluminum `chloride-hydrocarbon complex or
tylene, normal butenes, isobutane and normal
other halide isomerization catalyst. The com
butane which method comprises fractionating
bustion characteristics may be modified iby the
said gas stream into a light fraction containing
addition of 5-40% aromatics. In many cases, a
propylene, isobutylene‘, butene-l, and isobutane
combination of these adjustments Will be de 50 and a heavy fraction containing butene-Z and
sirable to» ñt the particular circumstances of de
normal b‘utane, polymerizing said light fraction
mand and supply at any particular refinery. In
under conditions for producing substantial yields
any case either a greater volume of a standard
of C7 polymers, separating said polymers from
grade of aviation gasoline, or a superior grade
unreacted gases, hydrogenating at least the C7
of the same amount of aviation gasoline results 55 fraction of said separated polymers, separating
by replacing isooctane 'by my hydrocodimer
an isobutane-butene-Z fraction from the sepa
alkylate blend.
rated unreacted polymerization gases, combining
From the above description it Will be seen that
said separated isobutane-butene-Z fraction with
I have attained the objects of my invention.
said heavy fraction and allcylating the resulting
My aviation gasoline contains large amounts of 60 mixture to form alkylate isooctane, isomerizing
parafñnic C7 hydrocarbons of high octane num
unreacted normal butane to form isobutane, in
ber as well as octanes obtained by alkylation
troducing said isobutane into said alkylation step
so that this gasoline is characterized not only
and blending at least a part of said alkylate iso
:by remarkably high octane number but also by
octane with at least a part of said hydrogenated
optimum volatility characteristics. I have ob 65 polymer.
tained maximum utilization of propylene and I
6. The method of making aviation gasoline
have utilized the butenes more effectively than
from a hydrocarbon gas stream containing
they have ever before been utilized for- the prep
propylene, isobutylene, normal butenes, isobu
arationvof aviation gasoline. Approximately one
tane and normal butane which method com
mol of aviation gasoline is pro-duced for every mol k70 prises fractionating said gas stream into a ñrst
of C4 oleñn available in the feed. Acid require
overhead fraction containing propylene and a
ments have been minimized in the alkylation step
ñrst bottom fraction containing butanes and bu
and the alkylation products have been improved
tenes, fractionating said ñrst lbottom fraction
both as to yield and as to octane number. Hy
to obtain a second overhead containing isobu
drogenation has been limited to a specific poly 75 tylene, butene-l and isobutane and a second bot
tom fraction containing butene-2 and normal
butane, combining said iirst oyerhead fraction
gases, combining said last-named 'gas stream
with said second bottoms fraction, alkylating said
combined gas stream and second .bottoms frac
with said second overhead fraction and polymer
tion to form an allgvlate “isoootane" and blend
izing said combined fractions 'under conditions
for obtaining heptenes, separating a fraction 5 ing at least a part of said aikylate “isooctane”
containingv said heptenes and hydrogenating said
fraction, separating a gas stream containing iso
butane and butene-2 from polymerization off
with said hydrogenated heptenes for producing
aviation gasoline. _
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