Compositions – Preservative agents – Anti-corrosion
Reexamination Certificate
1999-03-15
2002-12-03
McKane, Joseph K. (Department: 1626)
Compositions
Preservative agents
Anti-corrosion
C548S348100, C548S349100, C548S352100
Reexamination Certificate
active
06488868
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a process for producing and a method for using a corrosion inhibitor composition for reducing the corrosion rate of a metal by a fluid having at least one corrosion agent. More specifically, the invention relates to synthesis and use of one or more quaternized compounds having a substituted diethylamino moiety, for example quaternized imidazoline(s) having a substituted diethylamino moiety, in such a corrosion inhibitor composition used in oil and gas-field applications.
BACKGROUND OF THE INVENTION
In order to reduce the rate of corrosion of metals, and particularly metals containing iron, from one or more metal corrosion agents present in a fluid (i.e., a gas, liquid, slurry or a mixture thereof) a corrosion inhibitor is frequently introduced into the fluid to reduce the rate of corrosion of the metal vessel, pipeline and/or equipment used to store and transport the fluid. In oil and gas-field applications, for example, corrosion inhibitors are added to a wide array of systems, including without limitation, cooling systems, refinery units, pipelines, steam generators and oil or gas producing units in efforts to combat a variety of types of corrosion.
One example of corrosion, among others, typically encountered in the transport of a fluid containing one or more corrosion agents (hereinafter simply referred to as “fluid”) is flow-induced corrosion. In the case of flow-induced corrosion, the degree of corrosion that occurs is presently believed to depend on a variety of factors, including the corrosiveness of the fluid itself, the metallurgy of the pipeline and the shear rate, temperature, and pressure of the fluid.
Also, to the extent that a corrosion inhibitor is used, the inhibitor's ability to reduce the rate of corrosion of a metal from flow-induced corrosion, among other types of corrosion, is presently believed to depend on at least two factors. One factor is the inhibitor's chemical affinity for the metal surface. A second factor is the inhibitor's resistance to breakdown under high shear conditions. Therefore, it is currently believed that the rate of corrosion, especially flow-induced corrosion, of a metal more likely will be reduced where the inhibitor has good chemical affinity for the metal surface and can resist breakdown under high shear conditions. Many inhibitors have been developed to reduce corrosion. However, their activity is sufficiently low that higher concentrations are oftentimes required to effectively treat a pipeline, most particularly where flow-induced corrosion is a problem, thereby increasing operating costs.
The presence of a free amine moiety in inhibitors, such as that described in U.S. Pat. No. 5,322,640, enhances the reactivity of the pendant alkyl amine group versus the unsubstituted nitrogen atom in the imidazoline ring. Various imidazoline derivatives are produced typically by reacting the imidazoline intermediate with stoichiometric amounts (i.e. 1:1 mole ratio) of an organic carboxylic acid, such as, for example, acrylic acid (CH
2
CH
2
COOH), which preferably reacts with the imidazoline's pendant alkyl amine group, to enhance its corrosion inhibition activity by increasing its partitioning into water.
Conventionally, the 1:1 intermediate: carboxylic acid mole ratio has been considered desirable because the pendant alkyl amine group would still have at least one free amine (e.g., a NH
2
group) available for interaction with a metal surface. Accordingly, until the disclosure of the present invention, those skilled in the art of synthesizing corrosion inhibitors refrained from reacting higher mole ratios of an organic carboxylic acid and/or producing imidazoline derivatives where the group pendant to the imidazoline ring contains a substituted diethylamino moiety, wherein the previously freely available pair of nonbonding electrons on the heteroatom of the pendant group would be less available for steric reasons. In turn, it was thought this would reduce the compound's ability to interact with a metal surface, and thereby reduce its overall inhibition activity.
A corrosion inhibitor is desired that has improved inhibition performance as compared with inhibitors presently used for treating systems experiencing flow-induced corrosion, among other corrosion problems.
A substantial number of corrosion inhibitors have been disclosed for reducing the rate of corrosion of metal-containing storage and transport systems More specifically, a number of corrosion inhibitors have been disclosed most particularly for treating flow-induced corrosion, including, among others, quaternized imidazolines. However, these imidazolines are believed to have insufficient shear resistance. Accordingly, a need exists for a corrosion inhibitor that reduces the rate of corrosion, for example flow-induced corrosion, of metals.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a method of using a corrosion inhibitor composition for reducing the corrosion rate of a metal by a fluid having at least one corrosion agent, said method comprising: (a) introducing said corrosion inhibitor composition into said fluid, said inhibitor composition having at least one compound wherein said at least one compound is a quaternized substituted diethylamino compound having the general formula:
wherein, R
1
is a moiety selected from the group consisting of: (i) substituted and unsubstituted, saturated and unsaturated alkyl groups having from about 5 to about 29 carbon atoms; (ii) substituted and unsubstituted, saturated and unsaturated alkyl groups having from about 5 to about 29 carbon atoms, wherein said alkyl group is at least oxygenized, sulfurized or phosphorylized; and (iii) combinations thereof; each R
3
is independently a moiety selected from the group consisting of —CO
2
H, —SO
3
H, —PO
3
H
2
, —CO
2
R
7
, —CONH
2
, —CONHR
7
and —CON(R
7
)
2
groups and combinations thereof; each R
7
is independently selected from the group consisting of hydrogen and linear and branched alkyl, aryl, alkylaryl, cycloalkyl and heteroaromatic groups having from 1 to about 10 carbon atoms, and combinations thereof; R
8
is hydrogen or a linear alkyl group having from 1 to about 10 carbon atoms; and n=0 to about 8, p=1 to about 5 and q=2 to about 10; and (b) contacting said metal with the fluid of step (a).
According to another aspect of the present invention, there is provided a process for producing a composition comprising at least a quaternized compound having a substituted diethylamino moiety, comprising the steps of: (a) selecting a first organic compound from the group consisting of: (i) substituted and unsubstituted, saturated and unsaturated fatty acids having from about 6 to about 30 carbon atoms; (ii) substituted and unsubstituted, saturated and unsaturated fatty acids having from about 6 to about 30 carbon atoms, wherein said fatty acid is at least oxygenized, sulfurized or phosphorylized; and (iii) combinations thereof; (b) selecting an alkyl polyamine from the group having the general formula:
H
2
N—CH
2
—(CH
2
)
p
—NH—(CH
2
)
q
—NH
2
wherein p=1 to about 5 and q=2 to about 10; (c) selecting a second organic compound from the group consisting of (i) substituted and unsubstituted, &agr;,&bgr;-unsaturated carboxylic fatty acids, and amide and ester derivatives thereof, having from about 3 to about 11 carbon atoms; (ii) substituted and unsubstituted, &agr;,&bgr;-unsaturated sulfonic and phosphonic fatty acids having from about 2 to about 11 carbon atoms; and (iii) combinations thereof; (d) mixing said first organic compound and said alkyl polyamine in a mole ratio in a range of from about 0.6:1 to about 1.2:1 to produce at least one intermediate compound, wherein said mole ratio is the total moles of said first organic compound to the total moles of said alkyl polyamine; and (e) mixing said at least one intermediate compound with said second organic compound to produce said composition.
DESCRIPTION OF THE INVENTION
Accordingly, one as
Breininger Thomas M.
Cummings Kelly L.
McKane Joseph K.
Ondeo Nalco Energy Services, L.P.
Saeed Kamal
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