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Патент USA US3091597

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May 28, 1963
Filed Nov. 25. 1960
United States Patent ()? ice
Patented May 28, 1963
Donald L. Klass, Barrington, and Vincent Brozowski,
Mundelein, Ill., assignors to The Pure Oil Company,
Chicago, 11]., a corporation of Ohio
Filed Nov. 25, 1960, Ser. No. 71,665
20 Claims. (Cl. 208-293)
consequently, far more than a stoichiometric vamount
of the sulfuric acid or oleum must ‘be used to achieve the
desired degree of color reduction. The resulting dilute
waste acid must be neutralized and removed from the
product, thereby increasing the caustic requirement to
far above the amount theoretically required.
One obvious solution to at least part of the problems
associated with the use of sulfuric acid or oleum is
to use sulfur trioxide in place of the acid, because no
This invention relates to a process for decolorizing 10 water is formed in the reaction. However, sulfur tri
oxide is much more reactive than sulfuric acid and oleum,
hydrocarbon mixtures and for improving the color sta
bility of hydrocarbon mixtures. More particularly this
invention relates to a method of decolorizing ‘and im
and it carbonizes many organic compounds when used
in the pure state, even at low temperatures. Furthermore,
sulfur trioxide is capable of reacting with ‘compounds
proving the color stability of hydrocarbon mixtures, such
as distillates, by treatment with sulfur trioxide complexes 15 which contribute little to the color or color-forming pro~
pensity of the mixture. Nevertheless, sulfur trioxide,
at a temperature su?icient to transform the color bodies
into colorless form and separating a decolorizcd and/or
usually diluted with air or sulfur dioxide to reduce its
color stable product.
The presence of color bodies of color-producing bodies
activity, has been used in the past to upgrade petroleum
derived stocks. But in practically all of these sulfur
in the industry for a long period of time ‘and many
processes have been developed for the purpose of over
capable of forming color bodies, and require cost-1y e?i
in hydrocarbon mixtures has been a source of di?‘iculty 20 trioxide processes the reaction goes too far, involving
coming deleterious color and color instability propensi
constituents other than the color bodies and compounds
cient temperature control to avoid excessive charring by
the ‘highly exothermic reactions.
ties in hydrocarbon mixtures. Distillation in the pres
Now, in accordance with this invention, we have ‘dis
ence of chemicals and rabsorbents, solvent extraction 25
that sulfur trioxide complexed with a suitable
processes, the use of color inhibitors, clay treating ‘and
complexing agent, such as dioxane, is elfective in remov
many other re?ning methods have been developed to im
ing color bodies from highly colored stocks without sig
ni?cant effect on the other constituents present, and
erties of hydrocarbon mixtures. Certain products that
have ‘been re?ned exhibit color instability. For example, 30 without the rigid temperature control required in pre
vious processes. For example, we have found that treat
in distilling treated pressure distillate, pressed distillate,
ment of a dark-colored “coker distillate” with sulfur tri
or bright stock solution, color disintegration becomes
prove the color, odor, stability and general physical prop
oxide-dioxane complex at temperatures as high as 90° C.
elfectively changes the color bodies to a form in which
distillation, would increase the cost. Raw distillate from 35 they can be removed by Water washing, or from which
a colorless product can be distilled.
cracking units, after acid treatment are bright-yellow
Accordingly, it becomes a primary object of this in
colored materials, although part of the color bodies are
vention to provide a process for removing color bodies
high boiling and may be separated by distillation. Other
from hydrocarbon mixtures.
portions decompose at high temperature and cause dis
An object of this invention is to provide a process for
coloration of the products.
an acute problem because these products are in market
able form.
Subsequent decolorizing treatments, after
The origin of color bodies in petroleum re?nery streams
is not really known. Such streams consist of liquid mix
tures of para?inic, olefinic, naphthenic and aromatic hy
drocarbons with the concentrations of the various types
of constituents varying in different streams. The colors
thereof may vary from light yellow to medium brown
to ‘black because of the presence of color bodies which
improving the color stability of hydrocarbon mixtures.
Another object of this invention is to provide a process
for removing color bodies from hydrocarbon mixtures by
treatment with sulfur trioxide complex.
A. further object of this invention is to provide a proc
ess for removing color bodies and improving the color
stability of hydrocarbon mixtures by treatment with sul
fur trioxide complex.
Still another object of the invention is to provide a
formed ‘by the reaction of the unsaturated linkages in
process for removing color bodies from, and mitigating
the ole?ns with air, sulfur, and other substances.
Some re?ning operations are more conducive than 50 their formation in, hydrocarbon mixtures by treatment
with sulfur trioxide complex, neutralizing the reaction
others to the formation of color bodies, or of precursors
products, and removing the resulting transformed color
for the future formation of color ‘bodies. For example,
the products of cracking operations are known to have
These and further objects will be described or become
increased tendency to become colored during processing
or storage. In some uses, such as in gasolines, the re 55 apparent as the speci?cation proceeds.
The drawing is a ?ow diagram to illustrate one em
sulting color, if not substantial, may not detract from
are from natural or arti?cial sources, and are probably
the value of the mixtures, but in other uses, such ‘as
bodiment of the invention.
The instant invention is directed to a process wherein
solvents for ?lm-forming resins, color is undesirable.
a ‘highly colored hydrocarbon mixture is reacted with
Many methods and procedures have been proposed in
the past for improving the color of petroleum products. 60 sulfur trioxide in the form of a complex, the resulting
reaction effluent is neutralized with alkali, and a sub
For example, one of the oldest and most widely used
stantially colorless product is recovered from the reaction
methods is to treat highly~colored stocks with sulfuric
mixture by vfractional distillation. More speci?cally, our
acid or oleum. However, for each organic compound to
process comprises the steps of (l) reacting a highly
be removed by this treatment there exists a de?nite mini
mum acid concentration, termed the “1r” value, below 65 colored mixture of hydrocarbons, such as a re?nery
stream or product, with a small amount of a sulfur tri
which the desired reaction will not occur. Water is
formed in the reactions too, thereby diluting the acid;
oxide complex; (2) neutralizing the products formed
with aqueous alkali; (3) removing the resulting Water
C., and a dark brown color, was added to the dioxane~
soluble color bodies by washing the reaction effluent with
sulfur trioxide complex which had been prepared from
water; and (4) distilling substantially colorless product
from the residuum. Optionally, the water-washing step
22 g. of dioxane and 20 g. of sulfur trioxide in 50 ml. of
ethylene dichloride. Only a small amount of heat was
(step 3) may be omitted and the neutralized ef?uent dis
tilled to recover the colorless product.
liberated, the temperature increasing from 20° C. to
about 24° C.
The resulting mixture Was stirred over a
In carrying out the process, the amount of sulfur tri
period of 30 minutes While the temperature was increased
oxide complex used is adjusted to the amount of color
to 90° C., very little change in the appearance of the
bodies and/ or color-forming bodies present in the hydro
brown mixture being observed, and was maintained at
carbon mixture. In‘ general, this amount of sulfur tri 10 90° C. and stirred for 1 hour, during which time the
color darkened slightly.
oxide complex will be proportioned to the degree of a
At the end of this period, the mixture was cooled to
color present, or color improvement desired, and rela
tively small amounts have ‘been found to give adequate
room temperature, treated with 60 m1. of water contain
decolorization or color stability. On a weight percent
ing 11 g. of sodium hydroxide, and Washed with Water.
basis, about 0.01 to 2.0% by Weight is su?icient for most 15 The aqueous extract contained dark-brown products.
Distillation of the organic layer yielded small amounts of
purposes. The minimum effective amount may be re
lated to the degree of unsaturation or concentration of
water, ethylene dichloride, and dioxane, and 78.0‘ ‘g. of
unsaturates in‘ the petroleum mixture. Thus the mini
colorless hydrocarbon product (bromine number 14,
mum effective amount may be from 0.05 to 0.20 mol of
IBP 250° C., EBP 315° C.). The small amount (8 g.)
sulfur trioxide complex per mol of double bond present 20 of brown residue which remained in the distilling ?ask
in the hydrocarbon mixture. In general, the amount of
probably could have been reduced by more e?icient Water
sulfur trioxide complex should be substantially less than
washing before distillation. The colorless product
1 mol per mol of ole?nic double bond in the hydrocarbon
amounted to about 65% of the charge stock. Distilla
mixture to avoid excessive sulfonation of the ole?nic and
tion of the raw feedstock in a batch fractionation still
aromatic content of the feed hydrocarbon. By substan 25 having about 11 theoretical plates, at a re?ux ratio of
tially less than a mol per mol ratio is meant that the
about 2/ 1, did not change the color to any signi?cant
upper limit of sulfur trioxide complex should not exceed
about 0.8 mol per mol of ole?nic double bond present.
More than this amount may be used provided the tem
A 120-g. portion of the “coker distillate” used in Ex
perature of the treatment does not exceed the threshold
ample l is added to the dioxane-sulfu-r trioxide complex
su'lfonation temperature for the main body of hydrocar
prepared from 11 g. of dioxane and 10 g. of sulfur tri
bons present. The sulfur trioxide complex as used in ac
oxide in 25 ml. of ethylene dichloride. Using substan
cordance with this invention may be a combination of
the same procedure used in Example 1, except that
sulfur trioxide with any agent capable of sharing an
the treatment is conducted at room temperature, about 99
electron with the sulfur atom and capable of liberating 35 g. of colorless distillate can‘ be recovered. In this exam
sulfur trioxide at the decomposition temperature of the
ple, the color of the distillate is greatly improved with
complex. Examples of suitable sulfur trioxide complexes
out signi?cant effect on any other constituents of the
SOs-pyridine complex
SO3-trimethylamine complex
SO3-triethylamine complex
sOg-dimethylformamide complex
SO3-dioxane complex
naphthenic, aromatic, and ole?nic hydrocarbons boil
ing in the range of about 145° to 450° F. and having an
NPA color of 4+, on treatment in accordance with the
SO3-diox-ane bis complex
SO3-thioxane complex
SO3-thioxane bis complex and
sOs-dimethylanilin'e complex
The reactivity of sulfur trioxide complexes varies with
the complexi-ng agent used therewith. For example, sul
fur trioxide-dioxane complex is an active sulfonating
A gasoline blend comprising a mixture of paraffnic,
procedure outlined in Example 1, yields a colorless
An odorless naphtha having a boiling range of about
430° to 550° F. and a color index of NPA of 41/2, on
treatment in accordance with the procedure of Example 1,
yields a colorless product.
agent, and when used in excessive amounts will effect the
sulfonation of a large amount of the ole?nic and/ or aro—
matic constituents present in‘ the feed mixture. Conse
from the reaction of butene and
quently, when using the more active complexes, care
should be exercised in controlling the amount of com 55 iso'butylene, having a color index of NPA 3%., on treat
ment in accordance with the procedure of Example 1,
plex used ‘and the reaction temperature, or both, to avoid
yields a colorless product.
this result. Certain of the complexes, such as SO3
pyridine complex do not have the property of sulfonating
the hydrocarbons to a great extent. SO3-pyridine com
A kerosene having an NPA color index of 21/2, on
plex, for example, does not react with benzene at 120° 60
treatment in accordance with the procedure of Example
C., but SO3-dioxane complex reacts slowly with benzene
1, yields a colorless product.
at room temperature. Accordingly, the temperature of
the reaction mixture of S03 complex and hydrocarbon
mixture should be maintained at about 60° C. to 100° C.
A cracked distillate having an NPA color index of
for the lesser reactive complexes listed heretofore, and 65 41/2, on treatment in accordance With the procedure of
no higher than about 120° C. The more reactive com
Example 1, yields a colorless product.
plexes may be successfully used at temperatures ranging
In order to illustrate that dioxane alone, which has
from 50° C. to 95° C., which would include the dioxane
been used as a decolorizing agent ‘for certain materials,
and thioxane complexes.
has no elfect on hydrocarbon mixtures, particularly dis
vln order to illustrate the invention, a number of exam 70 tillates, the following example is given:
ples are given:
A l20-g. portion of “cokcr distillate,” having a bro
“Coker distillate,” 200 .ml., was treated with 1001 ml. of
mine number of 33, an IBP‘ of 249° C., an EBP of 320° 75 dioxane. The resulting dark-amber liquid was a homoge
neous one-phase system. Extraction with four 100-ml.
portions of distilled water gave the following results:
Appearance of
Light yellow.
Very light yellow.
complex is by titration. The activity of the complex is
under close control where necessary, and excessive treats
are avoided by tailor~making the complex for the particu
lar type of hydrocarbon or color body to be treated.
The required amount of complex can 'be predetermined
by tests and then the prescribed amounts metered into
the re?ning stream or system as a slurry, or, in some in
stances, as a solution in an inert solvent.
In some cases
the S03 complexes may be used as mixtures of more
10 than one type and applied either in liquid, vapor, or
solid form. With those hydrocarbons which are unre
The dioxane is apparently quantitatively removed from
active to sulfur trioxide, the S03 complex may be formed
the coker distillate-dioxane mixture by the aqueous ex
in situ by ?rst adding the complexing agent and then
traction. The residual distillate was slightly improved
adding the sulfur trioxide.
in. color, but there was no signi?cant removal of color 15
The process of this invention may be applied to any
bodies. Distillation of the residual distillate in vacuo
liquid or liqui?able hydrocarbon or hydrocarbon mixture
gave 190 ml. (95%) of recovered ‘distillate. This mate
which can be bene?tted by decolorization, whether the
rial was green. Thus, there is ‘de?nite color improvement
color therein is from a natural source, has been formed as
on treatment with dioxane, extraction, and then distilla
a result of deterioration of the hydrocarbon, or has been
tion, but the recovered material is not colorless.
20 added through some processing lor blending operation.
In addition, such dioxane complexes as dioxane-di
The term “hydrocarbon” or f‘hydrocarbon mixture” is
bromide, dioxane-diiodide, dioxane—picrate, and the hy
drogen chloride and bromide oxonium salts ofdioxane
intended to include substantially pure liquid hydrocarbons,
mixtures of diiferent hydrocarbons, natural hydrocarbon
do not have suf?cient reactivity to be useful in the in
products, various re?nery products such as gasolines,
stant process.
25 kerosenes, distillates, cracked distill-ates, alkylates, isom
A typical process based on our invention is shown
schematically in the accompanying drawing.
erization products, cracking products, polymerization
products, hydrogenation products, clay-treated products,
trioxide is introduced through line 10 into reactor 12
:cyclization products, and various naphthas, light distil
where it combines with inert solvent and dioxane, enter
lates, solvent naphthas, and V.M.P. naphthas. These
ing through line 14, to ‘form a solution or slurry of com 30 various hydrocarbons may contain additives and the like,
plexed sulfur trioxide. Make-up solvent and dioxane are
as long as they do not interfere with the decolorization
admitted through lines 16 and 18v as required. The re‘
process. The boiling range of the hydrocarbons may
sulting slurry of complex in solvent passes through line
vary from about 80° F. to 650° F. or higher. Speci?c ex
20 to treating tank 22, where it is mixed and reacted
amples of materials that may be bene?tted by the process
with ‘feedstock entering through line 24. The resulting 35 of this invention are gasolines, kerosenes, paint solvents,
mixture passes through line 26 to neutralizing tank 28,
cleaner’s solvents, butene-isobutylene alkylates, coker
where it contacts aqueous alkali solution introduced
distillates, and any of the series of products known as
through line 30.
solvent naphthas and aromatic solvents.
From tank 28, thehydrocarbon phase, consisting of
As an example of the preparation of coker distillate,
treated stock, solvent, and dioxane, flows through line 40 reduced crude, from which the volatile materials have
32 to distillation tower 34, while the aqueous phase, con
been removed, is pumped through a surge tank and pre
ta‘ining dissolved color bodies, is withdrawn through
heated to about 650° F. The preheated reduced crude
line 36. Treated, substantially colorless product, along
is passed through a heated coil, maintained at a tempera
with dioxane and solvent, is transferred from tower 34
ture :of about 7 50-900" F., and passed to the bottom of
through line 38 to distillation tower 40, while colored
a fractionating tower wherein virgin gas oil is ‘one of
residue is withdrawn through line 42. Dioxane and
the primary products. The unvaporized portion of the
solvent are transferred from tower 40 through line 44 to
reduced crude together with a recycle material obtained
dryer 46, while colorless product is withdrawn through
from the coker drums, to be described, is passed from
line 48. Dried'dioxane and solvent are recycled from
the bottom of the fractionator to a coking heater. The
' dryer 46 through line 14 to reactor 12.
products from the coking heater, at a temperature of about
The reaction of the hydrocarbons or hydrocarbon mix 50 900 to 920° F. pass into the bottom of two coking cham
ture to ‘be decolorized with sulfur trioxide in complexed
bers. The coking chambers are of such size as to re
'form may be conducted in the liquid, vapor, or mixed
quire approximately 24 hours to ?ll with coke and to
phase, and no particular apparatus or procedure need
achieve continuity of ‘operation, one chamber receives
'be followed, i.e., the reactants may be introduced in any the
preheated residue from the fractionator while coke
order, preheating of the reactants may be practiced and 55 is being removed from the other. The vapor products
various types of agitators or recycle techniques may be
?rom the coking drums, at a temperature of about 800
applied. The decolorizing treatment of this invention
to 820° F., are passed to the bottom of the fractionator.
may be applied in a manner to permit introduction of
Fractionation of these two feeds produces 'one or more
the S03 complex and treatment at the existing tempera-.
products which are primarily ole?nic and which may be
ture at any point in the re?ning operation.
used alone or in admixture as feed for the instant inven
Several advantages come ‘from the process. The sul
tion. These products are a gas oil, boiling at about 550
furic acid content of the treated stock is almost nil. The
to 850° F.; a furnace oil, boiling at about 400° to 600°
reaction can be made to proceed at any rate by the
F.; a naphtha, boiling at about 250 to 420° F.; and a
proper choice of S03 complex.
Adequate control ofv
270 EP unstable gasoline. Each product is passed through
’ the process is assured by preparing or complexing the 65 a stripper and accumulator before ?nal separation. A
sulfur trioxide before it contacts the hydrocarbon to be
typical operation of a coker unit will consume about
treated. Various S03 complexes now known have dif
fering degrees of activity, and selection of the complex
7,000 b.p.d. ‘of reduced crude and produce about 500
to 600 b.p.d. of unstable gasoline, 400 to 700 b.p.d. of
ing agent may be made so as to permit use of the process ,
naphtha, 400 to 700 b.p.d. of light distillate (furnace oil),
' in conjunction with ‘other re?ning processes. Complexes 70 and from 1,200 to about 4,000 b.p.d. of heavy distillate
may be selected which can be stored in ordinary ves
sels and in contact with air or moisture. Close control
of the severity of treat can be had by control of the
or gas oil.
Table I shows the general characteristics of the source
reduced crude and the products therefrom which may be
amount of sulfur trioxide in the complex. One method ,
of determining the amount of sulfur trioxide in the 75 used as starting materials for this invention.
is nonmal-ly used to insure their complete neutralization
Table I
and subsequent removal from the decolorized product.
The separation of the aqueous neutralized color bodies
and other products from the alkali treatment may be ac
complished by decanting, centrifuging, or other known
Naphtha Gasoline
Gravity _____ __
________ __
IBP _________ __
Pour Point...
Percent sulfur.
OR _________ __
Br. N o
—15 t8 __________________ __
0.53-0.69 0.21-0.46 0.16-0.23
6. 5-7. 20
0. 05-0. 15
________ __
0 15-0. 20
0 14-0. 20
________ __
The following table gives the characteristics of typical
gasoline, naphtha, light gas oil, and heavy gas oil products
which may be used in accordance with this invention
along with the characteristics of speci?c reduced crudes
which may be used as starting materials in a coker unit
to produce said products.
separation methods.
In determining the color of the products prepared in
accordance with this invention the S'aybolt chromometer
may be used, following the test method ASTM D 156—53T
In gen
eral, the term colorless, as used herein, is intended to
10 as applied to petroelum solvents and naphthas.
mean ASTM No. l, NPA No. 1, or lily-white to clear as
The embodiments of the invention, in which an exclu
sive property or privilege is claimed, are de?ned as fol
1. The process of decolorizing hydrocarbons which
comprises contacting said hydrocarbons with sulfur tri
oxide complex and separating a substantially color-free
Table 11
Starting Materials
11 111'
1g+ 282
GaSOnne ----------- -- i +20V+
Naphtha ----------- -- i
L‘ght Gas 011 ------ -- 1
(on to Cu; Cut)
Heavy Gas 011 ----- -
2. 3i
Reduced Crude ____ 1. { """"" "
4 s
(go. )
Gravity No. degrees 100° F
8. 21
0. 44
"-766- "6-6-9
""" "
Although the invention has been illustrated by various 40 product, said sulfur trioxide complex being a combination
examples, it is not to be limited thereby. The invention
of sulfur trioxide with an organic agent having an atom
relates particularly to the treatment of hydrocarbon dis
containing unshared electrons and capable of liberating
tillates which are otherwise di?icult to treat, as exempli
sulfur trioxide at the decomposition temperature of the
?ed by coker distillates which may vary in properties
depending somewhat on the source materials from which 45
2. The process of decolorizing hydrocarbon mixtures
they are prepared. In general, coker distillates having
which comprises contacting said mixtures with sulfur tri
bromine numbers in the range ‘of 30 to 40, and a boiling
oxide complex under conditions whereby said sulfur triox
range of about 240° C. to 350° C., which are brown
ide complex reacts with the color bodies therein ‘and sep
to dark brown in color, have been found to be successfully
arating a substantially color-free product from the un
treated in accordance with this invention. Since coker 50 reacted sulfur trioxide complex, said sulfur trioxide com
distillates represent a particularly di?icult material to
plex being a combination of sulfur trioxide with an or
treat, it is unexpected that the instant novel process re
ganic agent having an atom containing unshared electrons
sults in almost complete decolorization thereof. Distil
and capable of liberating sulfur trioxide at the decompo
lates from petroleum sources and other processes which
sition temperature of the complex.
are less di?icu-lt to decolorize may advantageously be 55
3. The process of decolorizing ole?nic hydrocarbon
‘treated in accordance with this invention, in lieu of other
mixtures which comprises reacting said mixtures with sul
'decolonizing methods because of the simplicity of the
fur trioxide complex at a temperature between ‘about 60°
process and the low cost of treatment. Since the other
and 120° C., said complex being present in an amount
materials or distillates disclosed herein are of known
suf?cient to supply about 0.05 to 0.20 mol of sulfur tri
origin and properties, there is no need to describe their 60 oxide per mol of ole?nic double bond present in said mix
properties or preparation in more detail. The aqueous
tures and recovering a substantially color-free product,
alkali used in the process may be an alkali metal hy
said sulfur trioxide complex being a combination of sulfur
droxide, such as sodium hydroxide, potassium hydroxide,
trioxide with an organic agent having an atom containing
lithium hydroxide, or an alkaline-earth metal oxide or
hydroxide, such as barium hydroxide, barium oxide, 65 unshared electrons and capable of liberating sulfur tri
oxide at the decomposition temperature of the complex.
calcium hydroxide, and calcium oxide. The aqueous
4. The process of decolorizing hydrocarbon mixtures
solutions of the alkali may be of any effective concentra
tion from dilute, or 1.0% by wt. solutions, to concen
trated or saturated solutions containing as much as 347
containing unstable color-forming ole?nic constituents
which comprises reacting said mixtures with sulfur tri
grams of sodium hydroxide, for example, per 100 this. of 70 oxide complex under conditions whereby said sulfur tri
oxide reacts with the unstable color-forming ole?nic con
water. The amount of ‘alkali used should be at least suf
stituents and separating a color-free product from said
?cient to react with all of the acidic reaction products
formed in the treatment with the sulfur-trioxide complex.
reaction mixture, said sulfur trioxide complex being a
‘The use of an excess, i.e., 1.0% to 20% over stoichio
combination of sulfur trioxide with an organic agent hav
metric amounts of alkali to react with the acidic products, 75 ing an atom containing unshared electrons and capable
of liberating sulfur trioxide at the decomposition temper
ature of the complex.
rating ‘sulfur trioxide at the decomposition temperature of
the complex.
5. The process in accordance with claim 4 in which the
hydrocarbon mixture is a hydrocarbon distillate.
6. The process in accordance with claim 5 in which the
hydrocarbon distillate is a coker distillate.
7. The process in accordance with claim 6 in which said
products are separated prior to distillation.
coker distillate is characterized by having a bromine num
ber of about 30 to 40, a boiling range of about 240° to
350° C., and is dark-brown in color prior to treatment.
8. The process in accordance with claim 4 in which the
sulfur trioxide complex is sulfur trioxide-dioxane.
9. The process in accordance with claim 4 in which
the sulfur trioxide complex is sulfur trioxide-pyridine.
14. The process in accordance with claim 13 in which
‘the Water-soluble color bodies and neutralized reaction
15. The process in accordance with claim 13 in which
the hydrocarbon mixture contains unstable color-forming
ole?nic constituents, and said sulfur trioxide complex is
present in an amount sufficient to supply about 0.05 to
0.20 mol of sulfur trioxide per mol of ole?nic double
‘bond present in the hydrocarbon mixture.
16. The process in accordance with claim 13 in ‘which
the sulfur trioxide complex is sulfur trioxide-dioxane.
17. The process in accordance with claim 13 in which
10. The process in accordance with claim 4 in which 15 the sulfur trioxide complex is sulfur trioxide-pyridine.
18. The process in accordance with claim 13 in which
the sulfur trioxide complex is sulfur trioxide-dioxane bis.
the sulfur trioxide complex is sulfur trioxide-dioxane bis.
11. The process in accordance with claim 4 in which
the sulfur trioxide complex is sulfur trioxide-thioxane.
12. The process in accordance with claim 4 in which
19. The process in accordance with claim 13 in which
the sulfur trioxide complex is sulfur trioxide-thioxane.
20. The process in accordance with claim 13 in which
the sulfur trioxide complex is sulfur trioxide-dimethyb 20 the sulfur trioxide complex is sulfur trioxide-dimethyl
13. The process of decolorizing hydrocarbon mixtures
References Cited in the ?le of this patent
which comprises contacting ‘said mixtures with sulfur tri—
oxide complex at a temperature of about 60° to 120° C., 25
neutralizing the products formed with an aqueous alkali,
and distilling a substantially colorless product from the
residuum, said sulfuro trioxide complex being a combina
tion of sulfur trioxide with an organic agent having an
atom containing unshared electrons and capable of liber
Steik ________________ __ Feb. 10,
Davis ________________ __ Feb. 6,
Archibald _____________ __ Jan. 1,
Fear _________________ __ Oct. 13,
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