Heat Transfer Fluids Containing Synergistic Blends of Corrosion Inhibitor Formulations

Abstract

Corrosion inhibitor formulations for use in heat transfer fluids include: (a) an optionally substituted benzoic acid or a salt thereof; (b) at least a first n-alkyl monocarboxylic acid or a salt thereof and a second n-alkyl monocarboxylic acid or a salt thereof, the first n-alkyl monocarboxylic acid and the second n-alkyl monocarboxylic acid being different; and (c) an azole compound. A ratio of weight percent of the first n-alkyl monocarboxylic acid or the salt thereof to weight percent of the second n-alkyl monocarboxylic acid or the salt thereof ranges from about 1:0.75 to about 1:2.00. A ratio of weight percent of the benzoic acid or the salt thereof to combined weight percent of the first n-alkyl monocarboxylic acid or the salt thereof and the second n-alkyl monocarboxylic acid or the salt thereof ranges from about 1:0.30 to about 1:2.25.

1 . A corrosion inhibitor formulation for use in a heat transfer fluid, the formulation comprising:
 an optionally substituted benzoic acid or a salt thereof;   at least a first n-alkyl monocarboxylic acid or a salt thereof and a second n-alkyl monocarboxylic acid or a salt thereof, wherein the first n-alkyl monocarboxylic acid and the second n-alkyl monocarboxylic acid are different; and   an azole compound;
 wherein a ratio of weight percent of the first n-alkyl monocarboxylic acid or the salt thereof to weight percent of the second n-alkyl monocarboxylic acid or the salt thereof ranges from about 1:0.75 to about 1:2.00; and 
 wherein a ratio of weight percent of the benzoic acid or the salt thereof to combined weight percent of the first n-alkyl monocarboxylic acid or the salt thereof and the second n-alkyl monocarboxylic acid or the salt thereof ranges from about 1:0.30 to about 1:2.25. 
   
     
     
         2 . The corrosion inhibitor formulation of  claim 1 , wherein the salt of the optionally substituted benzoic acid comprises an alkali metal. 
     
     
         3 . The corrosion inhibitor formulation of  claim 1 , wherein the salt of the optionally substituted benzoic acid comprises sodium benzoate, potassium benzoate, or a combination thereof. 
     
     
         4 . The corrosion inhibitor formulation of  claim 1 , wherein the salt of the first n-alkyl monocarboxylic acid and the salt of the second n-alkyl monocarboxylic acid each comprises an alkali metal. 
     
     
         5 . The corrosion inhibitor formulation of  claim 1 , wherein the first n-alkyl monocarboxylic acid and the second n-alkyl monocarboxylic acid are each independently selected from the group consisting of heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, and a combination thereof. 
     
     
         6 . The corrosion inhibitor formulation of  claim 1 , wherein one of the first n-alkyl monocarboxylic acid and the second n-alkyl monocarboxylic acid comprises heptanoic acid and the other comprises nonanoic acid. 
     
     
         7 . The corrosion inhibitor formulation of  claim 1 , wherein one of the first n-alkyl monocarboxylic acid and the second n-alkyl monocarboxylic acid comprises octanoic acid and the other comprises decanoic acid. 
     
     
         8 . The corrosion inhibitor formulation of  claim 1 , wherein the azole compound is selected from the group consisting of benzotriazole, tolyltriazole, mercaptobenzothiazole, tetrahydro tolyltriazole, and a combination thereof. 
     
     
         9 . The corrosion inhibitor formulation of  claim 1 , wherein the ratio of the weight percent of the first n-alkyl monocarboxylic acid or the salt thereof to the weight percent of the second n-alkyl monocarboxylic acid or the salt thereof ranges from about 1:1.00 to about 1:2.00. 
     
     
         10 . The corrosion inhibitor formulation of  claim 1 , wherein the ratio of the weight percent of the first n-alkyl monocarboxylic acid or the salt thereof to the weight percent of the second n-alkyl monocarboxylic acid or the salt thereof ranges from about 1:1.00 to about 1:1.50. 
     
     
         11 . The corrosion inhibitor formulation of  claim 1 , wherein the ratio of the weight percent of the first n-alkyl monocarboxylic acid or the salt thereof to the weight percent of the second n-alkyl monocarboxylic acid or the salt thereof is about 1:1. 
     
     
         12 . The corrosion inhibitor formulation of  claim 1 , wherein the ratio of the weight percent of the benzoic acid or the salt thereof to the combined weight percent of the first n-alkyl monocarboxylic acid or the salt thereof and the second n-alkyl monocarboxylic acid or the salt thereof ranges from about 1:0.50 to about 1:2.25. 
     
     
         13 . The corrosion inhibitor formulation of  claim 1 , wherein the ratio of the weight percent of the benzoic acid or the salt thereof to the combined weight percent of the first n-alkyl monocarboxylic acid or the salt thereof and the second n-alkyl monocarboxylic acid or the salt thereof ranges from about 1:0.75 to about 1:2.00. 
     
     
         14 . The corrosion inhibitor formulation of  claim 1 , wherein the ratio of the weight percent of the benzoic acid or the salt thereof to the combined weight percent of the first n-alkyl monocarboxylic acid or the salt thereof and the second n-alkyl monocarboxylic acid or the salt thereof is about 1:1. 
     
     
         15 . The corrosion inhibitor formulation of  claim 1 , further comprising a water-soluble molybdate salt. 
     
     
         16 . The corrosion inhibitor formulation of  claim 1 , further comprising sodium molybdate, potassium molybdate, or a combination thereof. 
     
     
         17 . The corrosion inhibitor formulation of  claim 1 , further comprising an additional component selected from the group consisting of an inorganic phosphate, an organophosphate, a water-soluble alkaline earth metal salt, a water-soluble alkali metal salt, a water-soluble zinc salt, a nitrite, a nitrate, a silicate, a silicate stabilizer, an acrylate-based polymer, a phosphonate, a phosphinate, and a combination thereof. 
     
     
         18 . The corrosion inhibitor formulation of  claim 1 , further comprising an alkaline earth metal oxide, an alkaline earth metal hydroxide, or a combination thereof. 
     
     
         19 . The corrosion inhibitor formulation of  claim 18 , wherein the alkaline earth metal comprises calcium, magnesium, strontium, or a combination thereof. 
     
     
         20 . The corrosion inhibitor formulation of  claim 1 , further comprising lithium oxide, lithium hydroxide, or a combination thereof. 
     
     
         21 . The corrosion inhibitor formulation of  claim 17  further comprising an additional component selected from the group consisting of a colorant, a biocide, an antifoaming agent, a surfactant, an additional corrosion inhibitor, a dispersant, or a combination thereof. 
     
     
         22 . The corrosion inhibitor formulation of  claim 17  further comprising at least one additional carboxylic acid or a salt thereof. 
     
     
         23 . The corrosion inhibitor formulation of  claim 22  wherein the ratio of the weight percent of the benzoic acid or the salt thereof to a combined weight percent of the first n-alkyl monocarboxylic acid or the salt thereof, the second n-alkyl monocarboxylic acid or the salt thereof, and the at least one additional carboxylic acid or the salt thereof ranges from about 1:0.50 to about 1:2.25. 
     
     
         24 . The corrosion inhibitor formulation of  claim 1 , wherein a pH of the corrosion inhibitor formulation at 50% concentration is between about 6.8 and about 9.0. 
     
     
         25 . The corrosion inhibitor formulation of  claim 1 , further comprising an inorganic phosphate, an organophosphate, or a combination thereof. 
     
     
         26 . The corrosion inhibitor formulation of  claim 1 , further comprising an ethylene glycol phosphate ester, 1,2,3-propanetriol phosphate, a phosphate polyether ester, a C 6 -C 12  alkyl alcohol ethoxylate phosphoric acid, an alkali metal salt of phosphate ester of cresyl ethoxylate, potassium cresyl phosphate, octylphenoxypolyethoxyethyl phosphate, octylphenoxy polyethyl phosphate, olyethylene glycol mono(octylphenyl) ether phosphate, an alkali metal salt of alkylphenoxypolyethoxyethyl phosphoric acid of R-phenyl(CH 2 CH 2 O) x  phosphate, wherein R is hydrogen or a C 1 -C 20  alkyl and x is an integer from 1 to 30, or a combination thereof. 
     
     
         27 . The corrosion inhibitor formulation of  claim 1 , further comprising at least one additional carboxylic acid or a salt thereof. 
     
     
         28 . The corrosion inhibitor formulation of  claim 27 , wherein the salt of the at least one additional carboxylic acid comprises an alkali metal, and wherein the at least one additional carboxylic acid comprises a C 6 -C 20  mono- or dibasic-aliphatic or aromatic carboxylic acid. 
     
     
         29 . The corrosion inhibitor formulation of  claim 28 , wherein the at least one additional carboxylic acid comprises 2-ethyl hexanoic acid, adipic acid, neodecanoic acid, sebacic acid, benzoic acid, para-toluic acid, tert-butyl benzoic acid, an alkoxybenzoic acid, isononanoic acid, 1,3,5-benzene tricarboxylic acid, 1,2,4-benzene tricaboxylic acid, 1,2,3-benzene tricarboxylic acid, or a combination thereof. 
     
     
         30 . The corrosion inhibitor formulation of  claim 1 , further comprising a water-soluble alkaline earth metal salt that will produce at least one of Ca 2+ , Mg 2+ , and Sr 2+  upon dissolving in water. 
     
     
         31 . The corrosion inhibitor formulation of  claim 1 , further comprising an acrylate-based polymer and a water-soluble alkaline earth metal salt that will produce magnesium ions, wherein a ratio of the acrylate-based polymer to the magnesium ions is greater than 5 and less than 25. 
     
     
         32 . The corrosion inhibitor formulation of  claim 1  wherein the optionally substituted benzoic acid comprises p-toluic acid, t-butyl benzoic acid, or a combination thereof. 
     
     
         33 . A corrosion inhibitor formulation for use in a heat transfer fluid, the formulation comprising:
 benzoic acid or an alkali metal salt thereof;   at least a first n-alkyl monocarboxylic acid or an alkali metal salt thereof and a second n-alkyl monocarboxylic acid or an alkali metal salt thereof, wherein the first n-alkyl monocarboxylic acid and the second n-alkyl monocarboxylic acid are different, and wherein the first n-alkyl monocarboxylic acid and the second n-alkyl monocarboxylic acid are each independently selected from the group consisting of heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, and a combination thereof;   an azole compound selected from the group consisting of benzotriazole, tolyltriazole, mercaptobenzothiazole, tetrahydro tolyltriazole, and a combination thereof; and   a molybdate salt comprising sodium molybdate, potassium molybdate, or a combination thereof;
 wherein a ratio of weight percent of the first n-alkyl monocarboxylic acid or the salt thereof to weight percent of the second n-alkyl monocarboxylic acid or the salt thereof ranges from about 1:1.00 to about 1:1.75; and 
 wherein a ratio of weight percent of the benzoic acid or the salt thereof to combined weight percent of the first n-alkyl monocarboxylic acid or the salt thereof and the second n-alkyl monocarboxylic acid or the salt thereof ranges from about 1:0.50 to about 1:2.00. 
   
     
     
         34 . The corrosion inhibitor formulation of  claim 33 , further comprising an additional component selected from the group consisting of an inorganic phosphate, an organophosphate, a water-soluble alkaline earth metal salt, a water-soluble alkali metal salt, a water-soluble zinc salt, a nitrite, a nitrate, a silicate, a silicate stabilizer, an acrylate-based polymer, a phosphonate, a phosphinate, and a combination thereof. 
     
     
         35 . A heat transfer fluid for use in a heat transfer system, the heat transfer fluid comprising:
 a freezing point depressant in an amount ranging from about 1 wt. % to about 99 wt. % based on a total weight of the heat transfer fluid;   water in an amount ranging from about 1 wt. % to about 99 wt. % based on a total weight of the heat transfer fluid; and   the corrosion inhibitor formulation of  claim 1 .   
     
     
         36 . The heat transfer fluid of  claim 35 , further comprising at least one additional component selected from the group consisting of a colorant, an antifoaming agent, a nitrate, a nitrite, a dispersant, an antiscalant, a surfactant, a wetting agent, a biocide, and a combination thereof. 
     
     
         37 . The heat transfer fluid of  claim 35 , wherein the freezing point depressant comprises an alcohol. 
     
     
         38 . The heat transfer fluid of  claim 37 , wherein the alcohol is selected from the group consisting of methanol, ethanol, propanol, butanol, furfurol, furfuryl alcohol, tetrahydrofurfuryl alcohol, ethoxylated furfuryl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, butylene glycol, glycerol, glycerol-1,2-dimethyl ether, glycerol-1,3-dimethyl ether, monoethylether of glycerol, sorbitol, 1,2,6-hexanetriol, trimethylopropane, methoxyethanol, and a combination thereof. 
     
     
         39 . The heat transfer fluid of  claim 37 , wherein the water is deionized water, demineralized water, softened water, or a combination thereof. 
     
     
         40 . The heat transfer fluid of  claim 35 , wherein the corrosion inhibitor formulation further comprises a water-soluble molybdate salt, a nitrite, or a combination thereof. 
     
     
         41 . A method of preventing corrosion in a heat transfer system, the method comprising:
 contacting at least a portion of the heat transfer system with a heat transfer fluid;   wherein the heat transfer fluid comprises:
 a freezing point depressant, water, or a combination thereof; and 
 the corrosion inhibitor formulation of  claim 1 . 
   
     
     
         42 . The method of  claim 41 , wherein the heat transfer system comprises a component made by controlled atmosphere brazing, a component comprising compacted graphite iron (CGI), a component comprising aluminum, or a combination thereof.