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Патент USA US2110403

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Patented Mar. 8, 1938
, 1,110,403 '
snrmrme H28 AND mnacAr'rANs mu
nrnnocaaaons '
Ludwig Bosenstein,
San Francisco,v cum. assign
or to Shell Development Company, San Fran
cisco, CaliL, a corporation of Delaware
Application June 10, 1935,
No Drawing-serial
No. 25.947
(Cl. 23-181)
This invention relates to the separation, by
means of an absorbent agent, of volatile acids
from hydrophobic liquids, i. e., liquids which are
immiscible with water, and especially mineral
5 hydrocarbon oils, which may be either normally
ture being treated and necessitate further treat
ment of the latter to purify the mixture and to
recover the bases. The hydrogen sul?de obtained
by my process may also be utilized to produce
sulfur, as by oxidation in a Claus kiln, or by re- 5
gaseous or normally liquid.‘ By the term "vola
acting it with sulfur dioxide produced by com
tile acids”, I mean those gases which in water ' bustion of a portion of the hydrogen sul?de.
I have tested the various absorbents commer
solution have an acid reaction, but which are
released unchanged ‘upon sufficient heating of
10 the water. Carbon dioxide, hydrogen chloride,
sulfur dioxide, mercaptans and‘ hydrogen sul?de
are the main gases of this type which are present
in the hydrocarbon mixtures» commonly en
countered in re?nery and industrial operations.
The process may be employed for the separa-‘
15 tion and recovery of these volatile acids from‘ the
liquid mixture, or may be employed to purify
other liquids by the removal of said acids there
cially utilized and have found them de?cient for
my purpose inv one respect or another. For ex- 10
ample, using a solution of sodium sulphide as ab
sorbent, the following. reversible reaction takes
On boiling~ the‘ solution after absorption of hy- 15
drogen sulphide. to substantial completion, the
reaction is reversed to the extent of only about
12% and consequently the absorption capacity '
More specifically, the invention relates to the‘ of the solution on continuous operation was so a
treatment of industrial liquids which contain small as to be impractical. On the other hand 20'
volatile acids, particularly hydrogen sul?de, such a solution of sodium carbonate absorbs hydrogen
as products from the destructive distillation of sulphide according to the reversible reaction:
coal, and various petroleum distillates, as, for ex
ample, lubricating oils,‘ fuel oils,_ kerosene,
straight run or cracked gasoline, light'naphthas,
On heating the solution .saturated with hydrogen
or lique?ed. normally gaseous hydrocarbons, etc.', ‘sulphide, only'a portion of the hydrogen sulphide
with an absorbent which permits the recovery of
’ volatile acids, particularly hydrogen sul?de, in a
was released, the other portion remaining in the
solution, thus:
a concentrated form, and substantially‘ free from
Hydrogen sul?de may be used as initial ma
terial for various end-products and it is, there
fore, desirable, for my purpose, to obtain hydro
35 gen sul?de as pure as possible. For example, if
it is desired to burn hydrogen sul?de to sulfur
dioxide as in the process for producing sulfuric
acid, ‘methods using organic bases or solutions
thereof to separate hydrogen sul?de are objec
40 tionable when the liquids from which His is sepa
rated contain or consist of hydrocarbons. Many
of these hydrocarbons are appreciably soluble in
such solutions and are su?iciently volatile to be
so that sodium sulphide accumulated in‘the solu
tion until the same condition was established as
in the preceding case.
I have discovered that aqueous solutions of 35
KaPO4, preferably concentrated, are suitable for
my'purpose as they absorb hydrogen sulphide
rapidly and evolve substantially pure hydrogen
sulphide on reversing the absorption reaction as
by boiling the solution at atmospheric, super
atmospheric, or law absolute pressures. ' The re
versal may be carried as far as desirable by con
tinued boiling, and when such boiling is practiced
released along with the hydrogen sul?de when
‘at an elevated temperature, the regenerated so- 45
the solution is heated. ‘Combustion of the re
lution may be cooled before returning to the
covered gas'can, therefore, lead\to combustion
absorption step. - In case the solution is boiled
productss’uch as carbon monoxide, which are un- - at a low pressure and corresponding low' tem
- desirable.‘ Moreover, most ‘of such organic bases - perature, cooling of the solution can be dispensed '
50 are appreciably soluble in the hydrocarbon mix
with prior to its return to thelabsorption step. 50
‘The regenerated solution may be
in batch,
be caused to flow countercurrently in an extrac
tion column. To liberate the hydrogen sul?de
‘A solution containing both mo; and mo. from, the absorbing solution a‘ regenerator of the
may be utilized to carry out the absorption of_ type shown in the U. S. patent to Bottoms,
hydrogen sulphide but I prefer to operate with a 1,789,901 may be utilized. Water which is'vapor
solution initially containing KsPOa only,‘ for ized with the hydrogen sulfide may be separated
while KaHPO4 in the initial solution results in a therefrom by a condenser at the top of the regen- '
erator, as disclosed by the patent, thus maintain
higher percentage of the absorbed hydrogen sul
ing the initial concentration of the absorbent
phide being evolved for any given time of re
agent substantially constant. If desired, water m
10 covery, it also decreases the capacity of the solu
intermittent or continuous processes.
may be introduced from an outside source at
' tion for .hydrogen sulphide by limiting the
amount of KaPO4 ‘which. can be ‘carried' in the suitable intervals or continuously to maintain the
solution. I have found that the effective hydro- . predetermined concentration of the absorbent. '
gen sulphide capacity of the solution is greatest agent if the condensate is not returned to the re
generator. Since the hydrogen sul?de leaving
the system is saturated with water, the water thus
removed ‘can be compensated for by introduction
for one'which initially contains only KsPOc.
Nevertheless, because of the more rapid regener
ation, solutions initially containing both K1PO4
from an outside source.
andK?iPO. may be found useful, as, for ex
' ample, in'a two stage system in which the liquid
is contacted in series.
Mercaptans and other ‘acidic gases may also be
removed from hydrocarbons with the liquid phase
Working with an aqueous solution of KsPOc, I potassium phosphate treatment of my invention.
have found that during absorption, KaPOa is con-_ Potassium phosphate will scrub out‘ hydrogen sul
?de in preference to mercaptans. ‘By limiting
the quantity of the potassium phosphate solution
to that approximately equivalent to the hydrogen
verted to KaHPO4, as shown by the reversible
sulfide content it is possible to recover substan-'
tially pure hydrogen sul?de. The alkalinity may
and I have found that 'this is the reaction whi
also be adjusted by using both H04 and KaHPOe,
so that practically no mercaptan's are removed.
When desired, such a treatment may be followed
by an additional stage to remove the weaker acidic
I‘have determined the desirablemaximum con
constituents, including mercaptans, and remain
centration at 25° C. to be_2.5'i mols KsPOc per _ ing hydrogen sul?de, if any, with a larger quantity v
v1000 g. aqueous solution. Such a solution is of scrubbing solution, and/or one of diiferent
88% saturated with respect to the potassium con _ alkalinity.
tent. If a more concentrated solution is used'at
I have found that certain petroleum fractions
this temperature, then the less soluble salt contain‘ aliphatic acids which are absorbed by
' (m) will tend to'crystallize'out in the ab-' ' the potassium phosphate solution, but cannot be - I
sorbing unit. Accordingly, the concentration > removed therefrom by simple heating. In'such
must be adjusted with respect to the KiHPO‘
40 formed during the absorption and/or added ini
tially so that no substantial crystallisation takes
place during absorption. At any temperature of
situations it is desirable to distill the hydrocar
bons and treat only. the fraction which does not
, operation, a too concentrated solution will deposit
be removed by subjecting the initial hydrocarbon
mixture to a preliminary washing treatment with
contain such acids, as, for example, the fraction
having a 100° C. end point.
crystals. However, if the concentration of the
45 solution is permitted to adjust itself by deposit‘
ing crystals then the resulting concentration will
be the desirable maximum.
_ I have found, contrary to all expectation, that
the sodium phosphates act quite differently from
These acids may also
There are. set forth hereinafter several ex
amples of my invention which it is understood are
exemplary .onLv.
Example I.—A number of test samples of a
potassium phosphates. First, the maximum us- > liquid hydrocarbon‘mixture consisting of about
able concentration of sodium phosphates is much _
less because of their lesser'solubilities, and second,
the reversal-of the absorption reaction is not
nearly as rapid or complete. This is probably
55 due
to a‘ formation of sodium sulphide in the
reverse reaction, thus:
29.9% propylene, 69% propane, and-1.1% E18 by,
weight were each separately subjected to single
batch extractions in the liquid state at room tem
perature with different amounts of aqueous solu 56
tions containing 2.0, 1.455 and 1.0 grams mols,‘
of KaPOr per kilogram, respectively. ' The weight
per cent of H118 remaining in each treated portion
Consequently, sodium phosphate solutions are‘. of the hydrocarbon mixture is given in Table I.
not nearly as e?icient as potassium phosphate
solution, and cannot be considered as equivalents
5 thereof.
Table I
The process can be conducted at various tem- .
peratures and pressures.‘ The contact between
the hydrocarbon mixture and the absorbing liq
uid may be obtained by passing the two liquids
into a mixing device, such as an agitator, per
. s'mpb N°'
solution per
oi hydromrmim
Quin-moi: KaPOr
“hm” _
0. 125
0 m
' may also be employed, and may be used in
75 processes. Alternatively, the two liquids may
t b'
y "km N
in hm
Per kilogram of
mitting the resulting mixture to form two phases,‘
and separating these phases by decantation, cen
trifuging, or any conventional method known to
the art. A series of such mixers and separators
multiple extraction or counter-current extraction '
1._ o
1- 1
. 271
. 021
1. 1
. 1D
1. 1 '
0. 250
i 010 ’
0. 500
- 002
L 000
. 021
. ‘l
i 00:
. 001
Example II.-A number of samples of a similar
Table IV
hydrocarbon mixture, but containing 2.1% H28
by weight were treated with various amounts 0!
Percent by weight HRS re
the potassium phosphate solutions as described
above in Example I.
The results are tabulated
Grams KsPO|
Sample No,
in Table 11-'
glaliintgg in hydrocarbon
Solution W
gram olhydro-
carbonmmm Liquid phase Gaseous phase
Table II
(13%” Kim" P“ 0m.‘ by fegghg H29
50 11
Sample No.
0. 0023
01 0086
0. 0047
These data show that scrubbing liquid hydro
carbons produces decidedly better result than
1' 455
3- $550 ,1;
0 250
Per kilogram of
G-mm mols K’Po‘
01430 01015
scrubbing the gas, especially in the situations in
which a high degree of removal of H28 is desired.
With a view of presenting comparable data to
{fig show the e?ect of varying the treating conditions
and concentrations all of the above examples per
39*; 31% 8' 3,1,2‘;
tain to propylene-propane mixtures. My inven
1. 000 ______ _- 01002
tion may, however, be applied with success to
other hydrocarbons which may be normally gas
eous or normally liquid. For example, light pe
Example III.-To illustrate the application of
the countercurrent method of extraction, a liq
uid hydrocarbon mixture of the composition de
scribed in Example I and an aqueous solution
containing 1.455 mols K3PO4 per kilogram were
30 continuously introduced into a two stage counter
current treater in the ratio of 235 grams of solu
tion to 1000 grams of hydrocarbon mixture. The
percentage by weight of ms remaining in the
hydrocarbon is given in Table III:
Table III
troleum fractions,ysuch as butane, pentane or 25
similar light fractions, petroleum naphtha,
gasoline, kerosene, as well as natural gasoline,
stabilizer bottoms, re?nery recovery hydrocarbon '
gases and recovering gasoline may be treated in
the liquid phase in accordance with the described 30
While I have in the foregoing described in some
detail certain preferred embodiments of my in
vention and some variants thereof, it will be
understood that this is only for the purpose of 35
making the invention more clear, and that the
invention is not to be regarded as limited to the
details of operation described, nor is it dependent
Per cent by weight H18
in hydrocarbon mix:
upon the soundness or accuracy of the theories
which have been advanced’ as to the reasons for
‘the advantageous results attained. On the other
hand, the invention is to be regarded as limited
only by the terms of the accompanying claims,
Inlet ____________________________ _.' _______ -_
1. 1
Outlet to ?rst plate ______________________ _.
Outlet to second plate ___________________ --
0. 047
0. 0016
in which it is my intention to claim all novelty
inherent therein as broadly as possible in view 45
of the prior art.
I claim as my invention:
I have found that treating the hydrocarbon in
the liquid state results in a substantial improve
50 ment over the corresponding treatment in the
gaseous or vapor state. The following example
demonstrates the superiority of my method over
the known vapor phase treatment:
Example IV-Four samples of the hydrocarb
mixture used in Example 11 (containing 2.1%
H28) were separately treated in the liquid state
in single batchv extractions with di?erent quan-v
titles of an aqueous solution containing 1.455
mols K1PO4 per kilogram, and the percent HzS
remaining in each treated sample determined.
Four other samples of the same hydrocarbon
mixture were treated with corresponding amounts
of the same potassium phosphate solution, but in
the gaseous state. The temperature and pres—
65 sure were almost the same for the treatments in
the gas and in the liquid phases. The per cent
by weight HaS remaining in each treated sample
is shown in Table IV:
1. In the process of separating H28 and nor
mally gaseous 'mercaptans from normally gas
eous hydrocarbons of less than ?ve carbon atoms 60
by treatment with an aqueous solution of potas
sium phosphate, the improvement consisting of
contacting said mixture while in the liquid ‘state
with the said aqueous solution containing tri
potassium phosphate under conditions to main
tain both, the material being treated and the
treating agent, in the liquid state.
2. In the process of, separating I-IaS and nor
mally gaseous mercaptans from normally gaseous
hydrocarbons of less than ?ve carbon atoms by 60
treatment with an aqueous solution of potassium
phosphate, the improvement consisting of con
tacting said mixture while in the liquid state with
the said aqueous solutioninitially containing di
and tri-potassium phosphate under conditions to 65
maintain both, the material being treated and
the treating agent, in the liquid state.
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