Coolant comprising azole derivatives for cooling systems in fuel-cell drives

• US 20060033074A1
• Filed: 10/20/2005
• Published: 02/16/2006
• Est. Priority Date: 06/13/2001
• Status: Active Grant

• Current Assignee: BASF AG (BASF SE)
• Original Assignee: BASF AG (BASF SE)
• Inventors: Wenderoth, Bernd, Dambach, Stefan, Meszaros, Ladislaus, Fidorra, Uwe
• Granted Patent: US 7,419,617 B2
• Time in Patent Office: Days
• US Class Current: 252/71
• CPC Class Codes: B60L 50/72 Constructional details of fuel cells specially adapted for electric vehicles
• CPC Class Codes: B60L 58/33 by cooling
• CPC Class Codes: C09K 5/20 Antifreeze additives therefor, e.g. for radiator liquids for application to surfaces C09K3/18; inhibiting corrosion by liquids C23F11/00
• CPC Class Codes: C23F 11/10 using organic inhibitors
• CPC Class Codes: C23F 11/149 Heterocyclic compounds containing nitrogen as hetero atom
• CPC Class Codes: H01M 8/04029 Heat exchange using liquids
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

An antifreeze concentrate for cooling systems in fuel-cell drives which gives ready-to-use aqueous coolant compositions having a conductivity of at most 50 μS/cm, based on alkylene glycols or derivatives thereof and containing one or more five-membered heterocyclic compounds (azole derivatives) having 2 or 3 hetero atoms from the group consisting of nitrogen and sulfur, which contain no or at most one sulfur atom and which may carry a fused aromatic or saturated six-membered ring.

Claims

1-8. -8. (canceled)

9. A ready-to-use aqueous fuel cell coolant composition having an initial conductivity of at most 50 mS/cm and which consists essentially of

(a) from 10 to 90% by weight of alkylene glycols or derivatives thereof,

(b) from 90 to 10% by weight of water,

(c) from 0.005 to 5% by weight of an azole derivative, and

(d) orthosilicates in an amount to provide the aqueous coolant composition with a silicon content of from 2 to 2000 ppm by weight, wherein

the azole derivative consists of one or more five-membered heterocyclic compounds having 2 or 3 heteroatoms selected from the group consisting of nitrogen and sulfur, which contain no or at most one sulfur atom and which may carry a fused aromatic or saturated six-membered ring.

10. A fuel cell cooling system comprising an aqueous fuel cell coolant composition having an initial electrical conductivity of at most 50 mS/cm, wherein said fuel cell coolant composition consists essentially of an alkylene glycol and water solution, and an azole derivative additive consisting of one or more five-membered heterocyclic compounds having 2 or 3 heteroatoms selected from the group consisting of nitrogen and sulfur, which contain no or at most one sulfur atom and which may carry a fused aromatic or saturated six-membered ring, and optionally an orthosilicate in an amount to provide a silicon content of from 2 to 2000 ppm by weight.

11. The fuel cell cooling system as claimed in claim 10, wherein the coolant composition consists essentially of from 0.05 to 5% by weight of the azole derivatives.

12. The fuel cell cooling system as claimed in claim 10, wherein the azole derivative is benzimidazole, benzotriazole, tolutriazole and/or hydrogenated tolutriazole.

13. The fuel cell cooling system as claimed in claim 11, wherein the azole derivative is benzimidazole, benzotriazole, tolutriazole and/or hydrogenated tolutriazole.

14. The fuel cell cooling system as claimed in claim 10, in which the alkylene glycol is monoethylene glycol.

15. A fuel cell cooling system comprising an aqueous coolant composition having an initial conductivity of at most 50 mS/cm and which consists essentially of

(a) from 10 to 90% by weight of alkylene glycols or derivatives thereof,

(b) from 90 to 10% by weight of water,

(c) from 0.005 to 5% by weight of an azole derivative, and

(d) orthosilicates in an amount which gives a ready-to-use aqueous coolant composition having a silicon content of from 2 to 2000 ppm by weight, wherein

the azole derivative consists of one or more five-membered heterocyclic compounds having 2 or 3 heteroatoms selected from the group consisting of nitrogen and sulfur, which contain no or at most one sulfur atom and which may carry a fused aromatic or saturated six-membered ring.

16. A method of cooling a fuel cell comprising providing in a fuel cell coolant system an aqueous fuel cell coolant composition having an initial electrical conductivity of at most 50 mS/cm, wherein said fuel cell coolant composition consists essentially of an alkylene glycol and water solution, and an additive consisting of one or more five-membered heterocyclic compounds (azole derivatives) having 2 or 3 heteroatoms selected from the group consisting of nitrogen and sulfur, which contain no or at most one sulfur atom and which may carry a fused aromatic or saturated six-membered ring, and optionally an orthosilicate in an amount to provide a silicon content of from 2 to 2000 ppm by weight.

17. The method of claim 16, wherein the coolant composition consists essentially of from 0.05 to 5% by weight of the azole derivatives.

18. The method of claim 16, wherein the azole derivative is benzimidazole, benzotriazole, tolutriazole and/or hydrogenated tolutriazole.

19. The method of claim 17, wherein the azole derivative is benzimidazole, benzotriazole, tolutriazole and/or hydrogenated tolutriazole.

20. The method of claim 16, wherein the alkylene glycol is monoethylene glycol.

21. A method of increasing the useful life of a fuel cell coolant composition consisting essentially of a glycol and water solution and having an initial electrical conductivity of at most 50 μ

S/cm, which method comprises adding to the fuel cell coolant composition an amount of from 0.05 to 5% by weight of an azole derivative sufficient to impart to the coolant composition a lesser increase in the electrical conductivity over time in use as compared to a coolant composition in which the azole derivative is absent.