Compositions – Reductive bleachant – deoxidant – reductant – or generative – Sulfur containing reductant – bleachant – deoxidant – or...
Reexamination Certificate
1999-11-23
2003-08-12
Medley, Margaret (Department: 1714)
Compositions
Reductive bleachant, deoxidant, reductant, or generative
Sulfur containing reductant, bleachant, deoxidant, or...
C210S904000, C423S266000, C423S562000
Reexamination Certificate
active
06605234
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to organic aminium counterions that are useful to prevent polysulfides from precipitating out of aqueous solutions, and to processes for using these counterions to produce sulfides, bisulfides, and/or polysulfides either to scavenge elemental sulfur or to prevent polysulfides from precipitating out of polysulfide solutions. The invention also relates to polysulfide solutions comprising these counterions, and to aqueous streams containing elemental sulfur complexed with these counterions. Most preferred streams contain cyanide ions before treatment, and comprise thiocyanate ions after treatment.
BACKGROUND OF THE INVENTION
Many refinery streams contain hydrogen sulfide and other sulfur-containing compounds. Many processes are aimed at removing sulfur components. However, sometimes the presence of sulfur in such refinery streams actually helps to protect the iron surfaces of the equipment used to handle this stream. Ammonium bisulfide reacts with iron at the surface of such equipment, forming an iron sulfide film. Once formed, the iron sulfide film isolates the iron surface from corrosive substances, thus preventing further corrosion.
If cyanide ion is present in the refinery stream, this delicate balance is disrupted. The cyanide ion reacts with iron ions which are freed from the FeS at equilibrium to form the very stable hexacyanoferrate (II) complex anion, which is water soluble. More and more iron ions are freed from the FeS as the system strives for equilibrium. These complexed iron ions are essentially removed as a factor in reaching equilibrium, and eventually all of the iron in the FeS film is released, exposing the fresh metal surface to corrosion. The problem is particularly acute in the sour water from fluid catalytic cracking (FCC) units.
Polysulfides, such as sodium and ammonium polysulfide, are known to control cyanide ions in waste water streams. Polysulfides convert the cyanide ions into noncorrosive, biodegradable thiocyanate ions. Thiocyanate ions do not react with FeS and are very water soluble, rendering them readily removable by water washing.
One problem with known polysulfides, such as ammonium polysulfide, is that they decompose under typical storage conditions, resulting in precipitation of free sulfur. As a result, the amount of active ingredient—sulfur—is greatly reduced, or even negligible. The precipitated sulfur also can foul or clog valves, pumps and lines, leading to expensive corrosion repair problems.
Stabilized polysulfide solutions with good cyanide scavenging capabilities are needed.
SUMMARY OF THE INVENTION
The present invention provides a composition comprising elemental sulfur complexed with organic aminium counterions, said composition having the following general formula:
HO—(CH
2
)
n
—N
+
R
1
R
2
R
3
S
x
=
R
3
R
2
R
1
N
+
—(CH
2
)
n
—OH
wherein n is from about 1 to about 6; x is from about 2 to about 10; and R
1
, R
2
, and R
3
independently are selected from the group consisting of hydrogen, hydroxyl groups, up to two aryl groups, alkyl groups having up to about 6 carbon atoms, and groups having the following general structure
R
4
—Y—R
5
—Z
wherein R
4
is selected from the group consisting of hydrogen, a hydroxyl group, an aryl group, and alkylene groups having up to about 6 carbon atoms; when R
4
is selected from the group consisting of hydrogen, a hydroxyl group, and an aryl group, R
5
and Z are nothing; when R
4
is an alkylene group having up to about 6 carbon atoms, R
5
is selected from the group consisting of hydrogen, a hydroxyl group, an aryl group, and an alkylene group having up to about 6 carbon atoms; when R
4
is selected from the group consisting of hydrogen, a hydroxyl group, and an aryl group, Y is nothing; when R
4
is an alkylene group having up to about 6 carbon atoms, Y is selected from the group consisting of a hydrogen atom, a hydroxyl group, an —NH group, a sulfur atom, an alkylene group having up to about 6 carbon atoms, provided that, when Y is a hydrogen atom or a hydroxyl group, R
5
and Z are nothing; when R
5
is selected from the group consisting of hydrogen, a hydroxyl group, and an aryl group, Z is nothing; when R
5
is alkylene group having up to about 6 carbon atoms, Z is selected from the group consisting of a hydrogen atom, a hydroxyl group, an NH
2
group, and a thiol group.
DETAILED DESCRIPTION OF THE INVENTION
Commercially available forms of polysulfides generally are aqueous ammonium polysulfide solutions having concentrations of polysulfides in the range of from about 30 wt % up to about 70 wt %. These solutions contain polysulfide ions which—when the solution is added to a cyanide-containing stream—react with cyanide ions in the stream to form thiocyanate ions.
The compounds of the present invention are elemental sulfur atoms complexed with organic aminium ions, which have the following general formula:
HO—(CH
2
)
n
—N
+
R
1
R
2
R
3
S
x
=
R
3
R
2
R
1
N
+
—(CH
2
)
n
—OH
wherein
n is from about 1 to about 6, preferably from about 2 to about 4;
x is from about 2 to about 10; and
R
1
, R
2
, and R
3
independently are selected from the group consisting of hydrogen, hydroxyl groups, up to two aryl groups, linear, branched, and cyclic alkyl groups having up to about 6 carbon atoms, and groups having the following general structure
R
4
—Y—R
5
—Z
wherein
R
4
is selected from the group consisting of hydrogen, a hydroxyl group, an aryl group, and alkylene groups having up to about 6 carbon atoms;
when R
4
is selected from the group consisting of hydrogen, a hydroxyl group, and an aryl group, R
5
and Z are nothing;
when R
4
is an alkylene group having up to about 6 carbon atoms, R
5
is selected from the group consisting of hydrogen, a hydroxyl group, an aryl group, and an alkylene group having up to about 6 carbon atoms;
when R
4
is selected from the group consisting of hydrogen, a hydroxyl group, and an aryl group, Y is nothing;
when R
4
is an alkylene group having up to about 6 carbon atoms, Y is selected from the group consisting of a hydrogen atom, a hydroxyl group, an —NH group, a sulfur atom, an alkylene group having up to about 6 carbon atoms, provided that, when Y is a hydrogen atom or a hydroxyl group, R
5
and Z are nothing;
when R
5
is selected from the group consisting of hydrogen, a hydroxyl group, and an aryl group, Z is nothing;
when R
5
is alkylene group having up to about 6 carbon atoms, Z is selected from the group consisting of a hydrogen atom, a hydroxyl group, an NH
2
group, and a thiol group;
wherein two or more of R
1
, R
2
, and R
3
may join together to form a cyclic or heterocyclic structure comprising up to 6 members.
In a preferred embodiment, the compound is “hydroxyethylaminium polysulfide,” in which n is 2, R
1
, R
2
, and R
3
are hydrogen, and x is from about 2 to about 10, most preferably 4.
Although the foregoing gives specific examples of organic aminium ions encompassed by the present invention, the invention encompasses organic aminium ions as long as their amine precursors are water soluble and sufficiently basic to form stable alkylaminium sulfide and polysulfide salts. The hydroxyalkylaminium sulfides or polysulfides may be used to solubilize unwanted sulfur. The hydroxyalkylaminium polysulfides may be used to provide cold stability to ammonium polysulfide solutions.
Where used to stabilize a polysulfide solution, the solution contains a sufficient amount of the organic aminium ions to maintain cold stability down to temperatures at which the resulting solution will be stored. Such temperatures will differ depending upon the customer and the end use for the particular product. Hydroxyalkylaminium polysulfides are more stable at low temperatures (i.e., will remain soluble in the customer's storage tank even when the temperature drops to about 40° F. or less), and have a much less obnoxious odor than ammonium polysulfide solutions and the vapors may contain less of the very toxic H
2
S.
Polysulfides having the foregoing structure may be made using sever
Go Ting S.
Roof Glenn L.
Baker Hughes Incorporated
Medley Margaret
Paula D. Morris & Associates P.C.
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