U.S. patent application number 12/836037 was filed with the patent office on 2012-01-19 for use of alpha-amino ethers for the removal of hydrogen sulfide from hydrocarbons.
Invention is credited to Dennis R. Compton, Juan M. Garcia, III, J. Byron Strickland.
Application Number | 20120012507 12/836037 |
Document ID | / |
Family ID | 45466088 |
Filed Date | 2012-01-19 |
United States Patent
Application |
20120012507 |
Kind Code |
A1 |
Compton; Dennis R. ; et
al. |
January 19, 2012 |
USE OF ALPHA-AMINO ETHERS FOR THE REMOVAL OF HYDROGEN SULFIDE FROM
HYDROCARBONS
Abstract
The invention provides a method of removing hydrogen sulfide
from hydrocarbon fluids. The method involves using an alpha-amino
ether as a hydrogen sulfide scavenger. This allows for the
introduction of an oil soluble scavenger in lieu of water-soluble
scavengers.
Inventors: |
Compton; Dennis R.; (Sugar
Land, TX) ; Strickland; J. Byron; (Bellaire, TX)
; Garcia, III; Juan M.; (Sugar Land, TX) |
Family ID: |
45466088 |
Appl. No.: |
12/836037 |
Filed: |
July 14, 2010 |
Current U.S.
Class: |
208/289 |
Current CPC
Class: |
C10G 2300/202 20130101;
C10G 2300/207 20130101; C10G 29/20 20130101 |
Class at
Publication: |
208/289 |
International
Class: |
C10G 29/20 20060101
C10G029/20 |
Claims
1. A method of reducing the amount of hydrogen sulfide in a
hydrocarbon fluid by contacting that fluid with an effective amount
of a composition comprising a hydrogen sulfide scavenger, wherein
the amount of hydrogen sulfide scavenger is sufficient to react
with the hydrogen sulfide to reduce the hydrogen sulfide found in
the vapor phase, the reaction product of the hydrogen sulfide
scavenger and the hydrogen sulfide remain soluble in the
hydrocarbon fluid, the hydrogen sulfide scavenger contains at least
one alpha-amino ether.
2. The method of claim 1 wherein the composition includes one item
selected from the list consisting of:
N,N'-oxybis(methylene)bis(N,N-dibutylamine),
N,N'-(methylenebis(oxy)bis(methylene))bis(N,N-dibutylamine), and
any combination thereof that may include
N,N,N'N'-tetrabutylmethanediamine.
3. The method of claim 1 in which the reaction product of the
sulfide scavenging formulation and the hydrogen sulfide do not form
a separate fluid layer.
4. The method of claim 1 further comprising the step of reacting a
secondary amine with a formaldehyde equivalent to form at least
some of the scavenging formulation.
5. The method of claim 1 in which the hydrocarbon fluid is a
liquid.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] None.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable.
BACKGROUND OF THE INVENTION
[0003] This invention relates generally to the treatment of sour
gas and liquid hydrocarbon to remove or reduce the levels of
hydrogen sulfide therein. The toxicity of hydrogen sulfide in
hydrocarbon fluids is well known in the industry. This has caused
considerable expense and efforts to be expended annually to reduce
its content to a safe level.
[0004] In large production facilities, it is generally more
economical to install a regenerative system for treating sour gas
streams. These systems typically employ a compound used in an
absorption tower to contact the produced fluids and selectively
absorb the hydrogen sulfide and possibly other toxic materials such
as carbon dioxide and mercaptans. The absorption compound is then
regenerated and reused in the system. Typical hydrogen sulfide
absorption materials include alkanolamines, PEG, hindered amines,
and other species that can be regenerated.
[0005] Nonregenerative scavengers for small plant hydrogen sulfide
removal fall into four general categories: 1) aldehyde based, 2)
metallic oxide based, 3) caustic based, and 4) other processes. In
the removal of hydrogen sulfide by nonregenerative compounds, the
scavenger reacts with the hydrogen sulfide to form a nonlethal
compound or a compound, which can be removed from the hydrocarbon.
For example, when formaldehyde reacts with hydrogen sulfide a
chemical compound known as formthionals (e.g., trithiane) is
formed.
[0006] Prior Art aldehyde scavengers typically include low
molecular weight aldehydes and ketones and adducts thereof. The low
molecular weight aldehydes may also be combined with an alkyl or
alkanolamine as disclosed in U.S. Pat. No. 4,748,011. Other
aldehyde derived scavengers include the reaction product of low
molecular weight alkanolamines and aldehydes as disclosed in U.S.
Pat. No. 4,978,512. PCT Application WO 92/01481 discloses a method
of reducing sulfides in different applications using certain
tri-substituted-hexahydro-s-triazines. German reference DE4027300
discloses a regenerative solvent for removing H.sub.2S and
mercaptans. U.S. Pat. No. 5,347,004 discloses the use of 1,3,5
alkoxyalkylene hexahydro triazines. PCT Application WO 91 US 5232
discloses hydroxyalkyl triazine scavengers, specifically an
N,N',N''-tris(2-hydroxyethyl)hexahydro-s-triazine. U.S. Pat. No.
5,774,024 discloses the combination of an alkyl triazine scavenger
and quaternary ammonium salt, where the quaternary ammonium salt
enhances the effectiveness of the alkyl-triazine. These prior art
attempts however are frequently water-based chemicals and require
significant mixing to allow the scavenger to effectively contact
the hydrocarbon fluid and remove the hydrogen sulfide.
[0007] Thus there is clear need and utility for an improved method
of scavenging hydrogen sulfide from hydrocarbon fluids using
scavengers that are soluble in the fluid that is being treated. The
art described in this section is not intended to constitute an
admission that any patent, publication or other information
referred to herein is "prior art" with respect to this invention,
unless specifically designated as such. In addition, this section
should not be construed to mean that a search has been made or that
no other pertinent information as defined in 37 CFR .sctn.1.56(a)
exists.
BRIEF SUMMARY OF THE INVENTION
[0008] At least one embodiment of the invention is directed towards
a method for removing hydrogen sulfide from a hydrocarbon fluid.
The method comprises contacting the fluid with an effective amount
of a composition comprising a hydrogen sulfide scavenger. The
amount of hydrogen sulfide scavenger is sufficient to react with
the hydrogen sulfide to reduce the amount hydrogen sulfide released
into the vapor space. The reaction product of the hydrogen sulfide
scavenger and the hydrogen sulfide remain soluble in the
hydrocarbon fluid. The hydrogen sulfide scavenger contains at least
one alpha-amino ether.
[0009] The composition may include one item selected from the list
consisting of: [0010] N,N'-oxybis(methylene)bis(N,N-dibutylamine),
[0011] N,N'-(methylenebis(oxy)bis(methylene))bis(N,N-dibutylamine),
and any combination thereof.
[0012] The reaction product of the sulfide scavenging formulation
and the hydrogen sulfide may not form a separate fluid layer. The
method may also further comprise the step of reacting a secondary
amine with a formaldehyde equivalent to form at least some of the
scavenging formulation. The hydrocarbon fluid may be a liquid.
DETAILED DESCRIPTION OF THE INVENTION
[0013] For purposes of this application the definition of these
terms is as follows:
[0014] "Alpha-amino ether" means a molecule according to the
formula:
##STR00001##
Where: R.sub.1, R.sub.2, R.sub.3, R.sub.4, are carbon containing
side chains containing 1-20 carbon atoms and includes cyclic and
acyclic compounds. The cyclic compounds can be aromatic or
non-aromatic. Examples include but are not limited to, methyl,
ethyl, propyl, tert-butyl, cyclopentyl, cyclohexyl, morpholino, and
phenyl, and they all can be the same group or one or more different
groups. B is an ether group, which is either an oxygen atom or a
group having an oxygen atom at both ends (such as --OCH.sub.2O-- or
--OC.sub.2H.sub.4O--).
[0015] "Formaldehyde equivalent" means a composition of matter
containing at least one group according to the formula:
(CH.sub.2O).sub.n in which n is an integer greater than or equal to
1, and/or a composition of matter including formaldehyde or related
molecules such as paraformaldehyde, and/or s-trioxane.
[0016] "Hydrocarbon fluid" means a liquid or gas predominantly
comprising organic material including but not limited to kerosene,
crude oil, crude oil emulsions, oilfield condensate, petroleum
residua, refined fuels, distillate fuels, fuel oil, heating oils,
diesel fuel, gasoline, jet fuel, bunker fuel oils, and any
combination thereof.
[0017] "Non-Regenerative Scavenger" means a scavenger, which is
consumed by the process of scavenging.
[0018] "Regenerative Scavenger" means a scavenger, which is not
consumed by the process of scavenging.
[0019] "Scavenger" means a composition of matter, such as but not
limited to alpha-amino ethers, useful in reducing the amount of or
mitigating the effects of some other composition of matter, such as
but not limited to hydrogen sulfide, in a fluid medium.
[0020] In the event that the above definitions or a description
stated elsewhere in this application is inconsistent with a meaning
(explicit or implicit) which is commonly used, in a dictionary, or
stated in a source incorporated by reference into this application,
the application and the claim terms in particular are understood to
be construed according to the definition or description in this
application, and not according to the common definition, dictionary
definition, or the definition that was incorporated by reference.
In light of the above, in the event that a term can only be
understood if it is construed by a dictionary, if the term is
defined by the Kirk-Othmer Encyclopedia of Chemical Technology, 5th
Edition, (2005), (Published by Wiley, John & Sons, Inc.) this
definition shall control how the term is to be defined in the
claims.
[0021] In at least one embodiment, the hydrogen sulfide in a
hydrocarbon fluid is reduced by the introduction of an alpha-amino
ether scavenger into the fluid.
[0022] In at least one embodiment the alpha-amino ether is a
portion of a scavenging formulation is used in a hydrocarbon fluid.
The formulation comprises alpha-amino ether and can consist of a
carrier liquid as well. The formulation can be introduced into the
hydrocarbon fluid by mechanical means including but not limited to
injection pumps or any mechanism disclosed in U.S. Pat. Nos.
5,744,024 and 5,840,177. In the context of gaseous hydrocarbon
fluids, the gas may be passed through an absorption tower
containing a scavenging formulation.
[0023] One advantage of the use of the alpha-amino ether scavenger
over other scavengers is that the alpha-amino ether scavenger is
soluble in hydrocarbon fluids, since it is not a water-based
product.
[0024] As illustrated in FIG. 1, in at least one embodiment the
hydrogen sulfide scavenger is produced by reacting a secondary
amine with formaldehyde or other formaldehyde equivalents such as
paraformaldehyde or s-trioxane. This produces a composition of
matter that predominantly comprises two forms of alpha-amino ethers
(compounds B and C). 10%-25% of the composition is a mono oxygen
ether (compound B) and 50%-80% of the composition is a bis oxygen
ether with a single carbon atom between the ether oxygens (compound
C). The reaction product also comprises 10-25% of the non-ether
diamine (compound A). Compound A is an unavoidable side product of
the reaction mixture. The reaction can be performed by mixing the
reactants in solvents such as but not limited to Naphtha
(Petroleum) Heavy Aromatic Solvents (such as Aromatic 150 and
Solvesso by ExxonMobil) or Naphtha Light Aromatic Solvents (such as
(Aromatic 100 by Americhem Sales Corporation).
[0025] In at least one embodiment the ratio of amine to
formaldehyde in the reaction mixture is inclusively within the
range of 1.5:1 to 1:1.5 and is preferably between 1.2:1 and
1:1.2.
[0026] In at least one embodiment any of the R and R' groups
correspond to any of the R.sub.1, R.sub.2, R.sub.3, and R.sub.4,
groups described in the definition of "alpha-amino ether".
[0027] In at least one embodiment when R is n-butyl and R' is H
then: [0028] Compound A is N,N,N',N'-tetrabutylmethanediamine,
[0029] Compound B is N,N'-oxybis(methylene)bis(N,N-dibutylene), and
[0030] Compound C is
N,N'-(methylenebis(oxy)bis(methylene))bis(N,N'-dibutylamine). At
least some contemplated scavenging compositions include
formulations comprising:
[0031] (Compound A, B, and C), (A and B), (A and C), (B and C), (C
alone), and (B alone).
EXAMPLES
[0032] The foregoing may be better understood by reference to the
following example, which is presented for purposes of illustration
and is not intended to limit the scope of the invention.
[0033] Samples of hydrocarbon fluids were tested to determine the
efficiency of the scavenger. Table 1 compares the inventive
composition in naphtha at 22 degrees C., Table 2 kerosene at 22
degrees C., and Table 3 slurry oil (such as carbon black oil,
decant oil, and clarified slurry oil produced in a refinery) at 97
degrees C. The samples contained variable levels of hydrogen
sulfide and were comparatively treated with various dosages of
alpha-amino ether scavenger or left untreated, and the amounts
H.sub.2S reduced in each sample was recorded.
TABLE-US-00001 Table 1: Naphtha 22.degree. C. H2S levles ppm H2S
Percent Dose Treatment (ppm) Reduced Reduction Ratio Time Untreated
800 Compounds A-C 20 780 97.5 0.2 2 h Compounds A-C 6 794 99.2 0.3
2 h Compounds A-C 3 797 99.6 0.2 24 h Compounds A-C <1 >799
99.9 0.3 24 h Compounds A-C 12 788 98.5 0.2 2 h (4) (796) (99.5)
(24 h) Table 2: Kerosine 22.degree. C. H2S levles ppm H2S Percent
Dose Treatment (ppm) Reduced Reduction Ratio Time Untreated 1400
Compounds A-C 400 1000 71 0.1 2 h Compounds A-C 220 1180 84 0.2 2 h
Compounds A-C 95 1305 93 0.3 2 h Table 3: Slurry oil 97.degree. C.
H2S levles ppm H2S Percent Dose Treatment (ppm) Reduced Reduction
Ratio Time Untreated 1300 Compounds A-C 450 850 65 0.1 2.5 h
Compounds A-C 240 1060 82 0.2 2.5 h Compounds A-C 180 1120 86 0.3
2.5 h Compounds A-C 140 1160 89 0.4 2.5 h Compounds A-C 90 1210 93
0.5 2.5 h
[0034] The amount of H.sub.2S present in the vapor space was
determined by measuring the vapor space hydrogen sulfide levels
according to ASTM D5705-03. The test procedure was modified by
running at temperatures other than 60.degree. C. A one-gallon
sample was divided into multiple 500 milliliter samples for
testing. The treated containers were pre-dosed with Compounds A-C
and then the fluid being tested was poured into the container.
[0035] In each example, the dose ratio was the number used to
determine the ppm treat rate for the sample. For table 1 the
untreated sample resulted in a vapor space hydrogen sulfide
measurement of 800 ppm. A dose ratio of 0.2 indicates the sample
was treated with 160 ppm of additive. A dose ratio of 0.3 indicates
that the sample was treated with 240 ppm of additive.
[0036] This data demonstrates that the presence of the alpha-amino
ether scavenger reduced the H.sub.2S in the hydrocarbon fluids in a
relatively short amount of time and continued to reduce the
H.sub.2S the longer the sample was exposed to the alpha-amino ether
prior to testing.
[0037] While this invention may be embodied in many different
forms, there are shown in the drawings and described in detail
herein specific preferred embodiments of the invention. The present
disclosure is an exemplification of the principles of the invention
and is not intended to limit the invention to the particular
embodiments illustrated. All patents, patent applications,
scientific papers, and any other referenced materials mentioned
herein are incorporated by reference in their entirety.
Furthermore, the invention encompasses any possible combination of
some or all of the various embodiments described herein and
incorporated herein.
[0038] The above disclosure is intended to be illustrative and not
exhaustive. This description will suggest many variations and
alternatives to one of ordinary skill in this art. All these
alternatives and variations are, intended to be included within the
scope of the claims where the term "comprising" means "including,
but not limited to". Those familiar with the art may recognize
other equivalents to the specific embodiments described herein
which equivalents are also intended to be encompassed by the
claims.
[0039] All ranges and parameters disclosed herein are understood to
encompass any and all subranges subsumed therein, and every number
between the endpoints. For example, a stated range of "1 to 10"
should be considered to include any and all subranges between (and
inclusive of) the minimum value of 1 and the maximum value of 10;
that is, all subranges beginning with a minimum value of 1 or more,
(e.g. 1 to 6.1), and ending with a maximum value of 10 or less,
(e.g. 2.3 to 9.4, 3 to 8, 4 to 7), and finally to each number 1, 2,
3, 4, 5, 6, 7, 8, 9, and 10 contained within the range.
[0040] This completes the description of the preferred and
alternate embodiments of the invention. Those skilled in the art
may recognize other equivalents to the specific embodiment
described herein which equivalents are intended to be encompassed
by the claims attached hereto.
* * * * *