Патент USA US2543956

Patented Mar. 6, 1951
~
2,543,953
UNITED STATES PATENT OFFICE
Elwood 'B...Backensto, Woodbury, N. J., assignor
.to Socony-Vacuum Oil Company, Incorporated,
_ va corporation of New York
’ ' NoJDrawing. Application November 21, 1947,
“serialtNo. 787,483
'13 Claims._ (0]. 196-29)
.2
The present invention relates to ,the sweeten
giveanegativedoctor test is usually accepted-as
ing . of . hydrocarbon , mixtures -,and, more particu
0.0004 per cent.
larly, to the sweetening of ,petroleumidistillates.
sweetening may be broadly de?nedas an-op
eration inwhich the concentration of the organic
Mixture .of hydrocarbons containing sulfhy
dryls canbe treated in accordance with several
procedures to produce 2. treated mixture which
sulfur compounds in .a hydrocarbon ,mixture .is
reduced to avvalue such .that the doctor test is
negative.
is negative to the “doctor test.” However, all of ‘
these procedures do ,not produce the same re-.
'
sult. .For example, ‘the so-called “doctor sweet
A hydrocarbon. mixture containing. sulfhydliyls
ening” .and the “copper .chloride” sweetening
is said-to .be “sourj’. orto bepositivein the com
methods ‘merely convert su?icient of the mer
mon “doctor test,” if it contains more than
about 0.0004 per centisulf-ur calculated as mer
captans present in the hydrocarbon mixture ‘to
disul?des , that the treated. mixture , is negative in
captan and .isfreefrom hydrogensul?dait is
the “doctor test.”
_
For gasoline to which ,tetrae
said to be f‘sweet” or to be negative in the "doc
ethylJeadis not to be added the presence of
tor test“ when the sulfur: concentration is below 15 the disul?des is notiobjectionable. Onthe other
that-‘value.
-
.
.
hand, thepresence of disul?des in gasoline .toj
whichtetraethyllead is to be added is objection-1'
able because the presenceof disul?des reduces
The “doctor test” comprises adding 10 cubic
centimeters of the oil to be tested to 5 cubic
centimeters of'sodium plumbitesolution (made
by dissolving 120 to 140 grams of sodium hydrox
the sensitivity of thegasoline to the addition of
the lead to even a greater extent than a corre
ide and 20.to 30 grams of litharge in‘a‘liter of
water) in a standard testbottle (4 ounce sample
sponding .concentration of mercaptans.
Since
mostgasolines now marketed are treated with
bottle, 33 millimeters inside diameter,=?tted» with
a clean cork stopper). The bottle‘isstoppered,
shaken for 15 seconds, and dryy?owersyof sulfur
tetraethylleadit follows that it is most desirablev
to remove the mercaptans rather than merely
(ground and screened to 100 to 200 mesh) added
to the mixture in quantity just suf?cient to cover
the interface (20 toix3-5emiliigrams). The bot
tle is again stoppered and shaken for ,15 ‘sec
onds. ,The test is reported positive if either the .30
removal of .‘mercaptans has become desirable.
To meet this demand, methods have been devised
which make it possible to remove substantially
all'of'the mercaptans. However, while it is usu-.
ally relatively easy to reduce the mercaptan sul-,
fur content of cracked and straight run gasoline
oil or the sulfur becomes discolored.
'
The minimum amount of mercaptan sulfur re
quired to give a positive doctor test in a sample
of Stoddard c1eaners’- solvent is shown in Table I.
‘Table I
Mereaptan
convertthem to disul?des. As a consequence, the
to a value of the order of 0.0007 to,0,003 per .cent
sulfur as mercaptan sulfur by treatment with‘
the"well-knownsolutizer solutions such as aque-'
ous caustic-tannin .and. aqueous caustic cresylate-_
tannin solution or other caustic-solutizer solu
tions, the reduction of the mercaptan-sulfur con
Minimum per cent
not
tentof
accomplished
gasoline from
as readily,
0.0007 or
On0.003
the other
to 0,0004
hand,
by weight of
mercaptan sulfur 40
gasoline containing 0.0007 to 0.003 per cent mer_-.
in naptha re
quired to give
captan sulfur is not “doctor, sweet.”
Positive Doctor
qTest
‘It hasnow been discovered that “sour,” hydroe,
carbonmixtures containing organic su1fhydryls_._
can‘betreated in a simple,inexpensive vbutee?ie,
cacious manner toprovide a “doctor sweet’? mix-_.
ture.
It is an object of the present inventionvto pro-,
videgamethodfor “sweetening" “sour”_ hydro~_
carbon mixtures. ,It isanother object of
Since hydrocarbonrmixtures usually contain two
or more mercaptans and since the distribution of
the mercaptansin hydrocarbon: mixtures is not
constant, a practical value for themaximum per
cent by weight "of"mercapta"n*sulfur"-"~which will
:
50, present invention to provide a. method for remov- .
ing a portion of the mercaptan content of a
“sour”,hydrocarbon mixture and, then to “sweet- '
en”-thepartially.demercantamzed, but sour, hy-,
drocarbonrnixturei ,ltis'afurther object. of the.
,present, invention to add a ‘hydrocarbon soluble
2,543,953
4
3
line and added sweetening agent are reacted for
sweetening agent to hydrocarbon mixtures con
a period of time dependent upon the temperature
taining not more than about 0.02 weight per cent
and concentration of the sweetening agent.
sulfur as organic sulfhydryls to produce a hy
The preferred sweetening agent at this time is
drocarbon mixture negative to the “doctor test.”
di-secondary butyl catechol. This catechol and
Other objects and advantages will become ap
several other compounds have been added to
parent from the following description.
“sweetened” gasoline, i. e. gasoline negative in
Two conditions, in general, will be met in the
the “doctor test” in the past to inhibit the forma
treatment of “sour” mixtures of hydrocarbons.
tion of gum during storage. However, the pres
The “sour” mixture may contain only about 0.005
weight per cent mercaptan sulfur or the “sour” 10 ent method of sweetening “sour” mixtures of hy
drocarbons distinguishes from this prior use of
mixture may contain appreciably more than
di-secondary butyl catechol. In the prior use
about 0.005 weight per cent mercaptan sulfur.
of this catechol and other gum inhibitors the
For the purpose of illustrating the present
gum‘ inhibitor was always added to “sweet” gaso
method, the treatment of sour gasoline contain~
ing not more than about 0.005 weight per cent 15 line which was negative in the “doctor test,” i. e.
contained less than‘ 0.0004 weight per cent of
mercaptan sulfur (including alkyl and aryl mer
mercaptan sulfur. In the prior use of these gum
captans, the latter often being termed thio
inhibitors the “sweet” gasoline did not contain a
phenols) ?rst will be described. When the gaso
trace of caustic. In contrast to the conditions
line contains hydrogen sul?de as well as not more
than about 0.005 weight per cent mercaptan 20 attendant upon the prior use of alkyl catechols
and other compounds in the inhibition of the
sulfur, the hydrogen sul?de is removed in a con
formation
of gum in “sweet” neutral gasoline, the
ventional manner by washing the gasoline with
alkyl catechols are employed under the following
an aqueous caustic solution. This caustic wash
conditions: The gasoline is sour, i. e. positive in
removes the hydrogen sul?de and a portion of
the “doctor test” and the gasoline contains at
the C1 and C2 mercaptans. However, the gaso
least a trace of alkali metal hydroxide and is
line will still be positive in the “doctor test.”
probably saturated with water. Furthermore,
The washed gasoline also contains a small amount
all of the prior-art gum inhibitors are not effec
of alkali metal hydroxide. The “sour” caustic
tive in the present method of sweetening gaso
washed gasoline containing not more than about
0.005 weight per cent mercaptan sulfur is sweet 30 line. This is established in the following tables.
ened by adding a small amount of a sweetening
Table II
agent and the sweetening agent allowed to re
act with the mercaptans. After about 30 min
Days at ambient
utes to about '7 days at ambient temperatures,
temperature to
dependent upon the concentration of the sweet
ening agent, the so-treated gasoline is negative
sweeten gasoline
lbs./l000 bbl. containingObOSwt.
Additive
'
% mercaptan and
alkali metal hy
droxide
to the “doctor test.” When it is unnecessary to
wash the gasoline with an aqueous solution of
alkali metal hydroxide, it is necessary to add a
None ________________________________________ __
trace, say about 0.001 pound to about 0.02 pound 40 Di-seeondary butyl catechol..__'.
20
Di-secondary butyl phenylene
of alkali metal hydroxide per barrel of gasoline.
diamine _____________________ ._
20
Illustrative of the treatment of a “sour” mix
ture of hydrocarbons containing appreciably
5
15
Trialkyl phenols _______ . _
20
Normal butyl amino phen
20
17
20
14
more than 0.005 weight per cent of mercaptan
sulfur, is that of a sour gasoline containing say 45
0.03 weight per cent mercaptan sulfur but free
from hydrogen sul?de. Such a gasoline is con
tacted with an aqueous solution of alkali metal
Alpha-naphthol ________ . _
Quinone ________________ __
__
20
Catcchol ______________________ ._
20
solutions of potassium hydroxide and potassium
5
more than 19
Table III
hydroxide or an aqueous solution of alkali metal
hydroxide containing a solutizer. Illustrative of 50
such solutions are the commonly used sodium hye
droxide-sodium cresylate solution which is 5.0
normal to sodium hydroxide and 2.0 normal so
dium alkyl phenolates; or the well know aqueous
-_ _
_
er 1000 bbls
‘
p
gasoline
present ______________________ ._
D
._
sweeten gasoline
'
containing 0.005 wt.
% mercaptan sulfur
0
l0
>
hydroxy benzene or a polyhydroxy benzene car
boxylic acid or a tannin or an aqueous potassium
Days at ambient
blag); cgist?bl temperatures ‘to
Alkali metal hydroxide
alkyl phenolates, or an aqueous sodium hydrox
ide~sodium cresylate solution containing a poly
hydroxide-potassium cresylate-tannin solution
l2
less than 1
>42
7
0
>42
10
>42
Table IV
60
or; in general, any of the aqueous alkaline solu
tizer solutions described in the voluminous litera
ture on this subject and known to those skilled in
the art may ‘be used. The "sour” gasoline is
treated with the aqueous alkaline solution until,
suf?cient of the mercaptans have been extracted
from the sour gasoline that although the treated
gasoline is still positive in the “doctor test” it does
not contain more than about 0.02 and preferably
less than about 0.005 weight per cent mercaptan 70
sulfur. The partially demercantanized "sour”
gasoline containing not more' than about 0.02
weight per cent mercaptan sulfur is separated
from the aoueous treating solution and sweetened
by adding thereto a sweetening agent. The gas'o-' 15
Lbs. alkyl catechol Days at ambient
per 1000 bbls. of gas temperatures to
oline containing al- sweeten; i. e. give a
kali metal hydrox-
negative “doctor
ide and 0.005 wt. %
mercaptan sulfur
O
13
0.25 -
7
0. 5O
.
test”
.
7
0.75
6
l. 0
2- 0
4
3
3. 0
’ 2
4. 0
5. 0
10. 0
20. 0
0. 83
0. 13
0. 04
~
0. O2
ear-scenes‘
5.
6
t'Ilhe 'i'data “presented in iFable 'ETI'I' establishes
that ‘cf :the :common igum =Iinhibitors.atested ;the
alkyl ‘oatechols .are far superior in the ipresent. _ Hydrocarbon mixture :
econftaming'ror?05
~it0 #01007
:weig'ht eper -.-cent mercaptan- '
sul ur.
method of “sweetening” zsour ‘hydrocarbon mix
Sweeteningadditivepragent
:
di~secondaryfbutyl catechol.
tures containing {about v0.005 weight per cent
of '- sweeteningeadditivel or :Iagent ': :5 .Land '10
mercaptan sulfur. ‘The . .- data ' presented "for. 6 Goncentration
mounds; pen-100.0, barrels.
'
v
I
_,
_
g
V
jtannin-sclutizcr"treatedjgasoline
catechol establishes ‘that unsubstituted catechol
is ineffective, if it 'does not vfactually :retard; ‘in
:
sweetening :of sour gasoline ' containing 10.005
weight per cent mercaptansulfur.
Q
‘
The data presented in "Table III establishes
that in the absence of alkali metal ‘hydroxide
-
V
,Sweetening'time,
.hours'
Inercap an-
seguellcgggealitléiitmn 0i
10
.
‘ ‘Weighij?
~
isvulfmé
‘
t
v
untreatedf '5 pounds ‘ 10 pounds
*
.:gasoline 1 per-1000 v
.
penlODO
bbls.
.bbls.
‘
even‘ di-secondary 'butyl catechol: at v a. concentra
tion of ~10 pounds {per 1000 barrels‘ of gasoline is
ineffective ~to :s-weeten ‘l sour ‘gasoline containing 15
about0éo051weightipericent mercaptan sulfur but
1-, aQ-asolinerl-sweetening.
I
"agent-{410% wash of aque-'
i
one 20%‘;=KOH __________ __
.
204005?
-.1.0
150
2, »Gas_o1~ine,+¢10% .rwiash .-.of
aqueous 20%
that ‘in - the presence of *alkali metal ‘hydroxide
l
'K'OH+
-ssweetening.~agent ________ _,
diesecondary 'butyl catechol is effective in
sweetening 'sour gasoline containing about"0.005
3, .Gasoline-l-Swecten-ing
weight per cent of mercaptan sulfur.
20
The-data presented in "Table IV establishes
that ‘in the presence of alkali metal hydroxide
the ratecf sweetening sour gasoline containing
about 0.005 ‘weight per cent mercaptansulfur ‘is
4
dependent upon the concentration » of ealkyl ‘cate
chol. A study of the data given in‘Table'IV
makesit manifest that-the amount ofal-kyl cate
chol to bee-used ‘in sweeteningsour hydrocarbon
agent-F30 parts per million of 3% alcoholic KOH;
‘
0.005
'
‘
F3
11
‘
,
‘ '0. 007'
20 __________ -_
Gasoline+sodinm ~ :salt ,of:
sweetening agent ________ __
0. 005
>90 I
1
1Practically instantaneous.
"The data in Table-Vestabhsh thatthe addition
of ‘thesweetening agent or "additive to :the ‘mix
ture of hydrocarbons before subjecting :the ;mix
ture to azcaustic washcausesa much more rapid
sweetening action than ‘that {achieved :by 1 adding
mixtures - containing not more than = 0:02 weight
theadditive after a caustic wash. ~Affurtherrim
per cent mercaptan sulfur will depend to a great 30 provement can be achieved by carrying out ‘the
extent upon local conditions-primarily local eco
treatment'in the presence .of a gas .:containing
nomic conditions. Thus, when a large vvolume
free oxygen, for examplegair or ievenzoxygenvper
of storage ‘is-available for 'a-week at a time and
se. The = data presented in ~F1Z1able
provide 1a
the ‘capacity ‘exceeds {the demand,v it ‘probably
basisiforthis ‘conclusion.
will be-m0st'~practica1>~t0 use about 0.25 pounds
of alkyl catechol ,per 1000 barrels in treating
gasoline containing about 0.005 weight per cent
Mixture ofhydrocarbons-z gasoline.
Mercaptamsulfur content, weight rperyzcent .merceptan
mercaptansulfu-r and. allow-the reaction to pro
ceed for several days at ambientxtemperatures.
On the other ~.hand, when su?icientqstorage ca
.snlfur :..0.0Q5.
Pounds 'of iii-secondary‘*butyl-catechql per “1000 barrels
of gasoline: 5.
, _
Sequence of addition of (reagents: .gasol1ne_plus sweeten
pacity is not available or demand is practically
~ing agent-plus "contact “with ' aqueous 20% QKOH.
equal tothe capacity to produce the sour gasoline,
it will probably'be most "practical to add about
'
4 to ‘about 20 pounds of alkyl catechol ‘per ‘1000
barrels of sour lhydrocarbon'mixture and allow 45
Condition
~
~Sweet
_
' ening
time
the reaction to proceed atambient temperatures
orto usesomewhat less,.say.2 to,5.,poun.ds, alkyl
alkali ,metal hydroxide.
Furthermore, when Storage ‘capacity, produc
tion and consumption justifgy such procedure .it
_
,Hours l 2
AirrExcluded ------ -T --------------- -_. ----------- -_,~g-_-._
>96
Air Present"
catechol and reflux the sour gasoline and alkyl
catechol in the presence of 1a small amount of
50
‘Accordingly, the present inventiongccmprises
sweetening asgur mixture of hydrocarbons con
wining not more than about .0-02 .per :cent and
is possible to sweeten gasoline and other mixtures
preferably ‘less than about ' 0.005 . per .cent :by
of ‘hydrocarbons such as kerosene, Diesel oil,
weight of mercaptan-sulfur'by the action of a
65
and heating oil containing up to 0.02 weight per
gum inhibitor selected from the group consist
cent of mercaptan sulfur without ?rst subject
ing of alkyl catechols, alkaryl diamines and
ing the mixture hydrocarbons to an operation for
quinones in the presence of alkali metal hydrox
partially de-mercaptanizing the hydrocarbon
ide. Preferably, the sweetening agent, i. e. the
mixture under such conditions larger amounts.
gum inhibitor, is added to the sour mixture of
say 3 to 5 times, of the predetermined additive 60 mercaptans before the mixture of hydrocarbons
is contacted with air and aqueous solution of
and larger amounts of caustic can be added to
alkali metal hydroxide. In addition, it is pre
the mixture of hydrocarbons and the mixture of
ferred to sweeten the sour mixture of hydrocar
hydrocarbons, sweetening additive, and caustic
bons in the presence of a/gas containing free
allowed to react for a longer period of time, say
up to three or four times that required to sweeten
65 oxygen.
I claim:
1. A method of producing a petroleum fraction
negative in the “doctor test” from a sour pel
The general procedure can be modi?ed further
with improved results. That is the rate of 70 troleum fraction containing not more than about
0.02 weight per cent of mercaptan sulfur which
sweetening can be accelerated by adding the
comprises mixing a sour petroleum fraction con
sweetening additive or agent before subjecting
taining not more than about 0.02 weight per
the mixture of hydrocarbons to a caustic wash.
cent mercaptan sulfur with a di-secondary bu
a similar mixture of hydrocarbons containing
about 0.005 weight per cent mercaptan sulfur.
The data submitted in Table V‘is a basis for the
foregoing statement.
tyl catechol in the presence of alkalimetalihy
75 droxide.
2,543,958
2. The method described and set forth in claim
1 in which the sour petroleum fraction and di
secondary butyl catechol are maintained at am
bient temperatures.
3. The method described and set forth in claim
1 in which the sour petroleum fraction and di
secondary butyl catechol are maintained at a
temperature between ambient temperatures and
the reflux temperature.
8
tion containing a polyhydroxy benzene carboxylic
acid to demercaptanize partially said fraction
and provide a treated fraction positive in the
“doctor test” and containing not more than about
0.005 weight per cent mercaptan sulfur, sepa
rating said treated fraction from said alkaline
solutizer solution, mixing said treated fraction
with di-secondary butyl catechol and maintain
ing the mixture of sour hydrocarbon mixture and
4. A method of sweetening a sour petroleum 10 alkyl catechol at a temperature between ambient
temperature and the re?ux temperature.
11. A method of producing mixtures of hydro
fraction which comprises partially demercaptan
izing a sour petroleum fraction to obtain a treated
carbons negative in the “doctor test” from sour
mixtures of hydrocarbons containing not more
than about 0.005 weight per cent mercaptan sul
petroleum fraction positive in the doctor test and
containing not more than about 0.005 weight
per cent mercaptan sulfur, separating said
treated petroleum fraction from the treating me
dium and, mixing said treated petroleum fraction
fur which comprises mixing a sour mixture of
hydrocarbons containing not more than about
0.005 weight per cent mercaptan sulfur and di
secondary butyl catechol in the presence of alkali
with a di-secondary butyl catechol in the pres—
ence of alkali metal hydroxide.
5. The method described in claim 4 in which
metal hydroxide.
12. A method of sweetening a sour mixture of
the mixture of treated petroleum fraction and
di-secondary butyl catechol is maintained at am
bient temperatures.
hydrocarbons which comprises adding a gum in
hibitor selected from the group consisting of di
secondary butyl catechol, di-secondary butyl
6. The method described in claim 4 in which
phenylene diamine and quinone to a sour mix
the mixture of treated petroleum fraction and
di-secondary butyl catechol is heated to re?ux
in the presence of alkali metal hydroxide.
ture of hydrocarbons containing not more than
about 0.02 weight per cent of mercaptan-sulfur,
and contacting said mixture of hydrocarbons and
'7. A method of sweetening a sour petroleum
said gum inhibitor with an aqueous solution of
fraction which comprises contacting a sour‘ pe
troleum fraction with an alkaline solutizer solu 30 alkali metal hydroxide.
13. The method described and set forth in
claim 12 in which the sweetening of the sour
tion containing a tannin to demercaptanize par
tially said fraction and provide a treated fraction
positive in the “doctor test” and containing not
more than about 0.005 weight per cent mercaptan
sulfur, separating said treated fraction from said
mixture of hydrocarbons is carried out in the
presence of a gas containing free oxygen.
ELWOOD B. BACKENSTO.
alkaline solutizer solution, and mixing said treated
fraction with di-secondary butyl catechol.
REFERENCES CITED
8. The method as set forth in claim '7 in which
The following references are of record in the
the butyl catechol and treated gasoline are heated
to re?ux temperatures.
‘
40
9. A method of sweetening a sour petroleum
fraction which comprises contacting a sour pe
troleum fraction with an alkaline soluti'zer solu
tion'containing a polyhydroxy benzene to de
?le of this patent:
UNITED STATES PATENTS
Number
2,369,771
2,413,945
mercaptanize partially said fraction and provide 45
a treated fraction positive in the “doctor test”
and containing not more than about 0.005 weight
per cent mercaptan sulfur, separating said treated
fraction from said alkaline solutizer solution, and
mixing said treated fraction with di-secondary 50
butyl catechol. '
10. A method of sweetening a sour petroleum
fraction which comprises contacting a sour pe
troleum fraction with an alkaline solutizer solu
Number
435,965
Name
Date
Bond ____________ __ Feb. 20, 1945
Bolt _____________ __ Jan. '7, 1947
FOREIGN PATENTS
Country
Date
Great Britain _____ __ Oct. 2, 1935
OTHER REFERENCES
Bond: “Regeneration of Caustic Solutions for
Gasoline-Oxidation,” reprint from Oil & Gas.
Jour., December 8, 1945.