Electrochemical and photoelectrochemical oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid and 2,5-diformylfuran
Electrochemical and photoelectrochemical cells for the oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid and/or 2,5-diformylfuran are provided. Also provided are methods of using the cells to carry out the electrochemical and photoelectrochemical oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid and/or 2,5-diformylfuran.
1. A method for the TEMPO-mediated electrochemical oxidation of 5-hydroxymethylfurfural in an electrochemical cell comprising: an anode in an anode electrolyte solution comprising 5-hydroxymethylfurfural; a TEMPO mediator immobilized on the anode or dissolved in the anode electrolyte solution; and a cathode in a cathode electrolyte solution, the method comprising: applying an anode potential to the anode, the anode potential being more positive than the onset potential for the oxidation of the TEMPO mediator, wherein TEMPO is oxidized at the anode to form TEMPO + , which induces the TEMPO-mediated oxidation of the 5-hydroxymethylfurfural to form 2,5-furandicarboxylic acid, 2,5-diformylfuran or both.
2. The method of claim 1 , wherein the anode electrolyte solution serves as an oxygen donor and the TEMPO-mediated oxidation of the 5-hydroxymethylfurfural forms 2,5-furandicarboxylic acid at a yield of at least 90%.
3. The method of claim 2 , wherein the TEMPO mediator is 2,2,6,6-tetramethylpiperidine-1-oxyl.
4. The method of claim 2 , wherein the TEMPO mediator is 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl.
5. The method of claim 1 , wherein the anode electrolyte solution is an aqueous electrolyte solution and the TEMPO-mediated oxidation of the 5-hydroxymethylfurfural forms 2,5-furandicarboxylic acid at a yield of at least 99%.
6. The method of claim 5 , wherein the TEMPO mediator is 2,2,6,6-tetramethylpiperidine-1-oxyl.
7. The method of claim 5 , wherein the TEMPO mediator is 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl.
8. The method of claim 1 , wherein the anode electrolyte solution is an aqueous solution having a pH of less than 12 and the TEMPO-mediated oxidation of the 5-hydroxymethylfurfural forms 2,5-furandicarboxylic acid at a yield of at least 90%.
9. The method of claim 1 , wherein the anode electrolyte solution does not serve as an oxygen donor and the TEMPO-mediated oxidation of the 5-hydroxymethytfurfural forms 2,5-diformylfuran at a yield of at least 94%.
10. The method of claim 1 , wherein the anode does not comprise platinum, palladium or gold.
11. The method of claim 1 , wherein the anode potential is below the onset potential for the oxidation of water to hydrogen.
12. The method of claim 1 , wherein the TEMPO mediator is 2,2,6,6-tetramethylpiperidine-1-oxyl.
13. The method of claim 1 , wherein the TEMPO mediator is 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl.
14. The method of claim 1 , wherein the 2,5-furandicarboxylic acid or the 2,5-diformylfuran are formed at a yield of at least 90%.