Corrosion inhibitor for systems with mixed metallurgy

Patent metadata

Field	Value
Publication number	US-12203176-B2
Application number	US-202016939897-A
Country	US
Kind code	B2
Filing date	Jul 27, 2020
Priority date	Aug 7, 2019
Publication date	Jan 21, 2025
Grant date	Jan 21, 2025

Abstract

A method of inhibiting corrosion of a metal surface in contact with an aqueous medium is provided. The method may include contacting the metal surface with a corrosion inhibitor composition where the corrosion inhibitor composition may include a phosphino succinic oligomer (PSO); an azole; and a molybdate. The disclosed corrosion inhibitor composition is especially useful for inhibiting corrosion in mixed metallurgy systems.

First claim

What is claimed is:

1. A method of inhibiting corrosion of a metal surface in contact with an aqueous medium, comprising:
contacting the metal surface with a corrosion inhibitor composition, the corrosion inhibitor composition consisting of:
water;
a copolymer of acrylic acid and 2-acrylamido-2-methyl propane sulfonate;
a phosphino succinic oligomer (PSO) consisting of a first, a second, and a third compound of formula I:

wherein n is 1 and m is 2 to 5 in the first compound;
n is 1 and m is 0 in the second compound; and
m is 1 and n is 1 in the third compound;
an azole that is tolytriazole (TT);
a molybdate; and
a buffering agent that is triethanolamine,
wherein the metal surface comprises aluminum,
wherein a ratio of the PSO to the azole in the corrosion inhibitor composition is about 2 to 1, and a ratio of the PSO to the molybdate in the corrosion inhibitor composition is about 2 to 1;
wherein the aqueous medium has a pH of from about 6 to about 8, and
wherein the corrosion inhibitor composition is added to the aqueous medium at a dosage rate from about 0.1% by volume to about 2% by volume.

2. The method of claim 1 , wherein the aqueous medium has a pH of from about 7 to about 8.

3. The method of claim 1 , wherein the aqueous medium has a chloride concentration of less than about 150 ppm.

4. The method of claim 1 , wherein the aqueous medium comprises about 10 ppm to about 10000 ppm of the PSO; about 2 ppm to about 50 ppm of the copolymer of acrylic acid and 2-acrylamido-2-methyl propane sulfonate; about 0.1 ppm to about 1000 ppm of the azole; about 0.1 to about 50000 ppm of the buffering agent; and about 0.1 ppm to about 5000 ppm of the molybdate.

5. The method of claim 1 , wherein the metal surface is at least part of an aluminum boiler.

6. The method of claim 1 , wherein a corrosion rate of the metal surface is less than about 1 mpy.

7. The method of claim 1 , wherein a corrosion rate of the metal surface is less than about 0.5 mpy.

8. The method of claim 1 , wherein the corrosion inhibitor composition does not include tin.

9. The method of claim 1 , wherein the corrosion inhibitor composition is added to the aqueous medium at a dosage rate from about 0.3% by volume to about 0.7% by volume.

10. The method of claim 1 , wherein the copolymer of acrylic acid and 2-acrylamido-2-methyl propane sulfonate has a molecular weight average of about 5,000 Da to about 50,000 Da.

11. The method of claim 1 , wherein the metal surface further comprises a second metal surface comprising mild steel, a third metal surface comprising copper, or a combination thereof.

12. The method of claim 1 , wherein the molybdate is sodium molybdate.

13. The method of claim 1 , wherein the PSO consists of about 20 to about 40 wt. % of the first compound, about 10 to about 40 wt. % of the second compound, and about 30 to about 60 wt. % of the third compound.

Assignees

• Ecolab Usa Inc

Inventors

• Chen Bingzhi
• Yin Zhangzhang

Classifications

• C23F11/185

  Refractory metal-containing compounds · CPC title

• C23F11/149

  Heterocyclic compounds containing nitrogen as hetero atom · CPC title

• Y02P20/10

  Process efficiency · CPC title

• C23F11/173

  Macromolecular compounds · CPC title

• C09D5/086

  Organic or non-macromolecular compounds · CPC title