Corrosion inhibitors for alkanolamines

Claim 2

A corrosion inhibiting composition for ferrous metals and its alloys in gas conditioning service using aqueous monoethanolamine to scrub carbon dioxide containing oxygen comprising: (a) a thiourea-aminopiperazine-formaldehyde polymer, and (b) a nickel ion producing material selected from the group consisting of nickel (II) salts, nickel (II) complexes and combinations thereof, wherein said thiourea-aminopiperazine-formaldehyde polymer is combined with said nickel ion producing material in a ratio of from 2 to 4 parts thiourea-aminopiperazine-formaldehyde polymer to 1 part nickel ion producing material.

Claim 3

The corrosion inhibiting composition of claim 1 wherein said nickel (II) salt is nickel carbonate.

Claim 4

The corrosion inhibiting composition of claim 1 wherein said nickel (II) complex is nickel acetate monohydrate.

Claim 5

The corrosion inhibiting composition of claim 1 wherein said polymer is thiourea-aminoethylpiperazine-formaldehyde.

Claim 6

The corrosion inhibiting composition of claim 1 wherein said nickel ion producing material is selected from the group consisting of: nickel (II) salts, nickel (II) complexes and combinations thereof.

Claim 7

The corrosion inhibiting composition of claim 5 wherein said nickel (II) salt is basic nickel sulfate.

Claim 8

The corrosion inhibiting composition of claim 5 wherein said nickel ion producing material is nickel sulfate hexahydrate.

Claim 9

A process for the preparation of a corrosion inhibiting composition comprising the steps of: (a) preparing an aqueous solution by mixing a thiourea with a primary or secondary amine; (b) adding formaldehyde to said aqueous solution with stirring and under conditions such that temperature is maintained at or below 50° C.; (c) preparing a solution of nickel ion producing material in alcohol by mixing a nickel ion producing material selected from the group consisting of: nickel (II) salts, nickel (II) complexes and combinations thereof in alcohol and combining the resulting solution with hydrochloric acid; (d) separating the nickel ion producing precipitate from said solution; and (e) combining said aqueous solution with said nickel ion producing precipitate in a ratio of 2 to 4 parts aqueous solution to 1 part nickel ion producing precipitate.

Claim 10

A process for the preparation of a corrosion inhibiting composition comprising the steps of: (a) preparing an aqueous solution by mixing a thiourea with a primary or secondary amine; (b) adding formaldehyde to said aqueous solution with stirring and under conditions such that temperature is maintained at or below 50° C.; (c) preparing a solution of nickel ion producing material in alcohol by mixing a nickel ion producing material selected from the group consisting of: nickel (II) salts, nickel (II) complexes and combinations thereof in alcohol and combining the resulting solution with hydrochloric acid; (d) separating the nickel ion producing precipitate from said solution; and (e) combining said aqueous solution with said nickel ion producing precipitate in a ratio of 2 to 4 parts aqueous solution to 1 part nickel ion producing precipitate.