METHOD OF PURIFICATION OF A REDOX MEDIATOR BEFORE ELECTROLYTIC REGENERATION THEREOF

• US 20020157965A1
• Filed: 02/16/2001
• Published: 10/31/2002
• Est. Priority Date: 02/16/2001
• Status: Active Grant

• Current Assignee: Hydro-Quebec (Province of Québec)
• Original Assignee: Hydro-Quebec (Province of Québec)
• Inventors: Amouzegar, Kamyab, Mahdavi, Behzad, Harrison, Stephen
• Granted Patent: US 6,468,414 B1
• Time in Patent Office: Days
• US Class Current: 205/688
• CPC Class Codes: C07C 45/36 in compounds containing six-membered aromatic rings
• CPC Class Codes: C07C 46/02 by oxidation giving rise to quinoid structures
• CPC Class Codes: C07C 46/04 of unsubstituted ring carbon atoms in six-membered aromatic rings
• CPC Class Codes: C07C 47/542 Alkylated benzaldehydes
• CPC Class Codes: C07C 50/12 Naphthoquinones, i.e. C10H6O2
• CPC Class Codes: C07C 50/24 containing halogen
• CPC Class Codes: C22B 3/20 Treatment or purification of solutions, e.g. obtained by leaching C22B3/18 takes precedence
• CPC Class Codes: Y02P 10/20 Recycling

Abstract

A method for purifying a Redox mediator used in a chemical process of oxidation of organic compounds. The desired purification is obtained by recovering the mediator in the form of a solution and heating this solution to evaporate the volatile impurities contained in it and to oxidize the non volatile impurities into compounds which precipitate and are extracted by filtration. The purification takes place before the mediator is regenerated in the electrolysis cell. This prevents the impurities contained in the mediator solution to negatively affect the operation of this cell.

Claims

1. A method for purifying a Redox mediator used in a chemical process of oxidation of organic compounds before said mediator is regenerated in an electrolysis cell, comprising:

recovering the mediator in the form of a solution containing volatile, soluble and insoluble impurities;

subjecting the solution containing the mediator to a thermal treatment, said treatment being carried out in a reactor that is maintained at a temperature that is high enough to allow oxidation of the impurities by means of the left-over unused catalyst present in the solution and to simultaneously allow elimination of the volatile impurities present in the solution; and

filtering the solution that contains the mediator to remove the insoluble impurities therefrom.

2. Method according to claim 1, further comprising:

adding to the reactor a given amount of the mediator regenerated in the electrolysis cell in order to increase the amount of said unused mediator present in the solution and therefore to complete oxidation of the impurities.

3. Method according to claim 1, wherein the thermal treatment is carried out at a temperature ranging between 40 and 120°

C.

4. Method according to claim 3, wherein the thermal treatment is carried out at a temperature ranging between 70 and 110°

C.

5. Method according to claim 4, wherein the thermal treatment is carried out at a temperature ranging between 90 and 100°

C.

6. Method according to claim 5, comprising:

adding to the reactor a given amount of the mediator regenerated in the electrolysis cell in order to increase the amount of the said unused mediator present in the solution and therefore to complete the oxidation of the impurities.

7. Method according to claim 1, wherein the Redox mediator is selected from the group consisting of Cr III/Cr VI, Ce III/Ce IV and mixtures thereof.

8. Method according to claim 5, wherein the Redox mediator is selected from the group consisting of Cr III/Cr VI, Ce III/Ce IV and mixtures thereof.

9. Method according to claim 6, wherein the Redox mediator is selected from the group consisting of Cr III/Cr VI, Ce III/Ce IV and mixtures thereof.

10. Method according to claim 1, wherein the chemical process of oxidation is a process synthesis of p-tolualdehyde from p-xylene.

11. Method according to claim 8, wherein the chemical process of oxidation is a process synthesis of p-tolualdehyde from p-xylene.

12. Method according to claim 9, wherein the chemical process of oxidation is a process synthesis of p-tolualdehyde from p-xylene.

13. Method according to claim 1, wherein the chemical process of oxidation is a process synthesis of naphtoquinone or its derivatives from naphtalene or its derivatives.

14. Method according to claim 8, wherein the chemical process of oxidation is a process synthesis of naphtoquinone or its derivatives from naphtalene or its derivatives.

15. Method according to claim 9, wherein the chemical process of oxidation is a process synthesis of naphtoquinone or its derivatives from naphtalene or its derivatives.

16. Method according to claim 1, wherein the chemical process of oxidation is a process synthesis of chlorobenzoquinone from chloraniline.

17. Method according to claim 9, wherein the chemical process of oxidation is a process synthesis of chlorobenzoquinone from chloraniline.

18. Method according to claim 1, wherein the chemical process of oxidation is a process synthesis of azelaic acid and pelargonic acid from oleic acid.

19. Method according to claim 8, wherein the chemical process of oxidation is a process synthesis of azelaic acid and pelargonic acid from oleic acid.

20. Method according to claim 9, wherein the chemical process of oxidation is a process synthesis of azelaic acid and pelargonic acid from oleic acid.