Oil soluble hydrogen permeation inhibitor

Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Maintaining environment nondestructive to metal

Reexamination Certificate

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C422S007000, C422S013000, C422S016000, C252S391000, C252S392000, C252S402000, C252S403000

Reexamination Certificate

active

06548016

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to compositions and methods for decreasing hydrogen permeation into metal equipment used in wet refinery environments containing hydrogen sulfide, ammonia, and cyanide.
BACKGROUND OF THE INVENTION
An area of concern in refinery operations is hydrogen permeation into the equipment of water handling systems used to remove water soluble contaminants in several parts of the refining process. Crude oil containing nitrogen and sulfur compounds gives rise to a variety of water soluble compounds when the crude is catalytically or thermally cracked and fractionated. These compounds include ammonia, hydrogen sulfide, hydrogen cyanide (HCN) and numerous organic species having ionizing cyanide, sulfide (S
2−
), or ammonium (NH
4
+
) substituents.
Ammonia is known to react with hydrogen sulfide to give ammonium sulfide, which reacts further with hydrogen sulfide to give ammonium bisulfide. The bisulfide ion reacts with iron at the surface of the handling equipment to form ferrous sulfide. At the same time, atomic hydrogen is liberated. The cyanide ion is believed to destabilize the iron sulfide and to retard the recombination of atomic hydrogen into gaseous hydrogen. As a result, the surface concentration of atomic hydrogen increases. Atomic hydrogen is small enough to pass through the crystal lattice of the steel and, because of the concentration driving force, to pass through the steel and into the atmosphere. In the process, the steel becomes saturated with hydrogen and is considered to be hydrogen charged.
Steel in a hydrogen charged condition is subject to several cracking mechanisms, including sulfide stress cracking, hydrogen blistering, and stress-oriented hydrogen-induced cracking. The hydrogen permeating through the steel will run into a flaw, a dislocation, or a hole in the metal. Hydrogen atoms that recombine at this location form hydrogen gas, which tends to become stuck in the steel because the molecules are too large to move through the steel crystal lattice. As more and more hydrogen gas is trapped in the flaw, the pressure inside the metal starts to build. When the pressure at the flaw reaches the yield strength of the metal, the mechanical properties of the metal start to fail.
A number of materials have been used to inhibit hydrogen-induced cracking of metal. Unfortunately, none of these materials has been entirely successful.
SUMMARY OF THE INVENTION
The present invention provides a composition and method for decreasing corrosion and permeation of hydrogen into metal equipment used in wet refinery environments containing hydrogen sulfide, ammonia, and cyanide comprising incorporating into a product stream handled by said equipment a composition comprising a polyamine amide of 3-hydrocarbyl thiopropionic acid in an amount sufficient to inhibit said hydrogen permeation.
DETAILED DESCRIPTION OF THE INVENTION
The inhibitor of the present invention is a polyamine amide of 3-hydrocarbyl thiopropionic acid having the following general formula:
wherein
n is between about 1-6;
wherein R
1
is a hydrocarbyl group comprising at least about 10 carbon atoms selected from the group consisting of straight, branched, and cyclic alkyl groups, alkenyl groups, and akynyl groups, aryl groups, alkaryl groups, and aralkyl groups, and heterocyclic alkyl groups containing oxygen or nitrogen as a ring constituent; and,
wherein R
2
is a nitrogen-containing group selected from the group consisting of a cyclic imide group and a hydrocarbyl amide group wherein a nitrogen in said nitrogen-containing group also comprises a nitrogen of said polyamide, and wherein said cyclic imide group further comprises between about 4-6 carbon atoms, and wherein said hydrocarbyl group has between about 1-20 carbon atoms selected from the group consisting of straight, branched, and cyclic alkyl groups, alkenyl groups, and alkynyl groups.
In a most preferred embodiment, R
1
comprises a hydrocarbyl group having between about 10-14 carbon atoms, most preferably about 12 carbon atoms, and R
2
is a nitrogen-containing group selected from the group consisting of a cyclic imide group and a hydrocarbyl amide group wherein a nitrogen in said nitrogen-containing group also comprises a nitrogen of said polyamide, wherein said cyclic imide group further comprises between about 4-6 carbon atoms, and wherein said hydrocarbyl amide group comprises at least one oxygen double bonded to said hydrocarbyl in addition to the double-bonded oxygen forming said amide group, said hydrocarbyl group having between about 10-14 carbon atoms selected from the group consisting of straight, branched, and cyclic alkyl groups, alkenyl groups, and alkynyl groups.
The manufacture of a most preferred embodiment results in a mixture of two predominant compounds: propanamide, N-[2-[2-[3-(dodecenyl)-2,5-dioxo-1-pyrrolidinyl]ethyl]amino]ethyl]-3-[dodecylthio]-2-methyl (“PDDPDM”), which has the following formula:
and, 15-thia-5,8,11-triazaheptacosanoic acid, 2-(dodecenyl)-13-methyl-4,12-dioxo (“TTDMD”), which has the following formula:
In other preferred permeation inhibitors, R
1
comprises a hydrocarbyl group comprising between about 10-14 carbon atoms, and R
2
is selected from the group consisting of a polyalkyleneamine, a nitrogen-containing group selected from the group consisting of a cyclic imide group, and a hydrocarbyl amide group, wherein a nitrogen in said nitrogen-containing group also comprises a nitrogen of said polyamine, and a hydrocarbyl group having between about 5-12 carbon atoms selected from the group consisting of straight, branched, and cyclic alkyl groups, alkenyl groups, and alkynyl groups, wherein said hydrocarbyl group comprises at least one substituent selected from the group consisting of a carboxyl group and an amine group.
Specific examples of such other preferred inhibitors include, but are not limited to the following, which are designated both by structure, and by their “CAS Index Name”:
CAS Index Name
15-Thia-5,8,11-triazaheptacosanoic acid, 4,12-dioxo-2-(2,4,4,6,6-pentamethyl-1-heptenyl);
CAS Index Name
Propanamide, N-[2-[[2-[[2-[(2-aminoethyl)amino]ethyl]amino]ethyl]amino]ethyl]-3-(dodecylthio)-
CAS Index Name
Propanamide, N-(5-amino-4-methylpentyl)-3-(dodecylthio)-2-methyl+Propanoic acid, 3-(dodecylthio)-2-methyl-2-(2-hydroxyethyl)-2-(hydroxymethyl)hexyl ester
and
CAS Index Name
Propanamide, N-[2-[[2-[[2-[(2-aminoethyl)amino]ethyl]amino]ethyl]amino]ethyl]-3-(dodecylthio)-2-methyl-+1-Propanol, 3-(dodecylthipo)-
and
CAS Index Name
Propanamide, N-[2-[[2-[[2-[(2-aminoethyl)amino]ethyl]amino]ethyl]amino]ethyl]-3-(dodecylthio)-2-methyl-+Propanoic acid, 3-(dodecylthio)-2-methyl-2-(2-hydroxyethyl)-2-(hydroxymethyl)hexyl ester
In order to measure the efficacy of a hydrogen permeation inhibitor, the hydrogen permeation of a given environment must be measured. The hydrogen charging capability of an environment is measured by the rate of proton discharge and the amount of hydrogen absorbed as a result. Electrochemical hydrogen permeation measurements allow the measurement of hydrogen flux through the material.
In the following experiments, the electrochemical test system was a Devanathan type cell in which a steel membrane or “coupon” acted as a bi-electrode. On one side of the membrane or “coupon” (the cathodic or charging side), a simulated fluid catalytic cracker (“FCC”) solution was added in which hydrogen was deposited due to wet H
2
S corrosion or artificial charging of the coupon. On the other side of the coupon (the anodic or collecting side), the evolved hydrogen quantity was measured. A separate, electrically isolated solution existed on the collection side of the coupon. Separate electrical circuitry made the anodic or collecting side of the coupon, at which hydrogen was evolved, an anode. Here, the hydrogen that

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