# US 7,410,596 B2 · Corrosion inhibiting solutions for absorption systems

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- Number: US 7,410,596 B2
- Document ID: US7410596B2
- Status: Granted
- Kind: B2
- Application number: 10/732,992
- Filed: 2003-12-11
- Published: 2004-06-24
- Granted: 2008-08-12
- Earliest claimed: 1999-09-07
- Assignees: Rocky Research
- Inventors: Shyam Kumar Verma; George Robert Sandor
- Web page: https://patentgrep.com/patent/US7410596B2

## CPC

- C09K 5/047: {for absorption-type refrigeration systems}
- C23F 11/06: in markedly alkaline liquids
- C23F 11/18: using inorganic inhibitors
- C23F 11/182: {Sulfur, boron or silicon containing compounds}
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25

## Abstract

Anti-corrosion solutions and processes useful for refrigeration processes are proposed. Heteropoly complex anions of transitional metal elements can be added to an absorption solution which includes aqueous ammonia, alkali metal hydroxide and/or alkaline earth metal hydroxide, optionally in combination with transition metal compounds or compounds of the metallic elements of Groups IIIa to VIa of the Periodic Table of Elements to minimize corrosion of systems within which the solution is used.

## Claims

### Claim 1

An aqueous absorption solution consisting of water, at least one alkali metal hydroxide, alkaline earth metal hydroxide, or a mixture thereof, and at least one heteropoly complex anion of a transition metal element present in an amount sufficient to provide a corrosion inhibiting effect, the alkali metal hydroxide, alkaline earth metal hydroxide or mixture thereof is present in an amount from about 20 to about 80 weight percent, based on the total weight of the solution and wherein said at least one heteropoly complex anion is a compound selected from the group consisting of [XaMbOc]-n, [XaZdMbOc]-n, [XaZdMbOcHe]-n, [XaMbOc(OH)f]-n, [XaZdMbOc(OH)f]-n, and mixtures thereof, wherein:
X and Z are central heteroatoms selected from the group consisting of elements from Groups I-VIII of the Periodic Table of Elements; a is 1 or 2; d is an integer from 0 to 4; MbOc, MbOcHe, and MbOc(OH)f are oxoanions in which M is a transition metal element; b is an integer from 5 to 22; c is an integer from 20 to 70; e is an integer from 0 to 6; and f is an integer from 0 to 3; and n is the charge of the anion.

### Claim 2 (depends on 1)

The solution of claim 1, wherein:
X is phosphorus, silicon, manganese, tellurium or arsenic; and
M is molybdenum or tungsten.

### Claim 3 (depends on 1)

The solution of claim 1, wherein said at least one heteropoly complex anion is a phosphomolybdate of the formula [PMo12O40]−3.

### Claim 4

An aqueous absorption solution for refrigeration systems consisting of water, at least one alkali metal hydroxide, alkaline earth metal hydroxide, or a mixture thereof, at least one phosphomolybdate, and at least one transition metal halide corrosion inhibitor, said phosphomolybdate and said transition metal halide corrosion inhibitor present in an amount sufficient to provide a corrosion inhibiting effect.

### Claim 5 (depends on 4)

The solution of claim 4, wherein said phosphomolybdate is [PMo12O40]−3, and said transition metal halide corrosion inhibitor is cobalt halide or nickel halide.

### Claim 6 (depends on 4)

The solution of claim 4, wherein said alkali metal hydroxide, alkaline earth metal hydroxide or mixture thereof is present in an amount from about 20 to about 80 weight percent, based on the total weight of the solution.

### Claim 7

An absorption solution for refrigeration systems consisting of water, at least one alkali metal hydroxide, alkaline earth metal hydroxide, or a mixture thereof, at least one phosphomolybdate, and at least one halide corrosion inhibitor of the metallic elements of Group Va of the Periodic Table of Elements, said phosphomolybdate and said halide corrosion inhibitor present in an amount sufficient to provide a corrosion inhibiting effect.

### Claim 8 (depends on 7)

The solution of claim 7, wherein said phosphomolybdate is [PMo12O40]−3, and said halide corrosion inhibitor is antimony bromide (SbBr3).