PRODUCTION OF 2,5-FURANDICARBOXYLIC ACID

Abstract

The invention is directed to the to the electrochemical preparation of 2,5- furandicarboxylic acid (FDCA) from 5-hydroxymethylfurfural (HMF) by electrochemical oxidation, comprising a first oxidation step of oxidizing HMF to 5-hydroxymethyl-2-furan-carboxylic acid (HMFCA) in an electrochemical cell, subsequently a first isolation step of isolating HMFCA, followed by a second oxidation step of HMFCA to FDCA.

Claims

1. A process for electrochemically preparing 5-hydroxymethyl-2-furan-carboxylic acid, said process comprising a first oxidation step of oxidizing 5-hydroxymethylfurfural to 5-hydroxymethyl-2-furan-carboxylic acid in an electrochemical cell, and subsequently a first isolation step of isolating 5-hydroxymethyl-2-furan-carboxylic acid.

2. A process for preparing 2,5-furandicarboxylic acid, said process comprising electrochemically preparing 5-hydroxymethyl-2-furan-carboxylic acid from 5-hydroxymethylfurfural in accordance with claim 1, followed by a second oxidation step of 5-hydroxymethyl-2-furan-carboxylic acid to 2,5-furandicarboxylic acid.

3. The process of claim 1, wherein the oxidation of 5-hydroxymethylfurfural to 5-hydroxymethyl-2-furan-carboxylic acid in the first oxidation step is carried out in an anode compartment of the electrochemical cell, said anode compartment comprising a gold-comprising anode.

4. The process of claim 1, wherein the electrochemical cell comprises an anode compartment and said anode compartment comprises an electrolyte comprising ammonium, sodium, potassium, calcium, magnesium, perchlorate, sulfate, hydrogen phosphate, a solid polymer electrolyte or a combination thereof.

5. The process of claim 1, wherein the first oxidation step is carried out in a solution having a pH of less than 14.

6. The process of claim 1, wherein a reduction reaction of a bio-based compound is carried out in a cathode compartment of the electrochemical cell.

7. The process of claim 6, wherein the bio-based compound is selected from the group consisting of ethanedioic acid, propanedioic acid, butanedioic acid, pentanedioic acid, hexanedioic acid, heptanedioic acid and combinations thereof.

8. The process of claim 1, wherein the oxidation is carried out in a cathode compartment of the electrochemical cell using a mediator.

9. The process of claim 1, wherein a reduction is carried out in a cathode compartment of the electrochemical cell, said reduction reaction comprising generating hydrogen gas.

10. The process of claim 8, wherein the mediator is hydrogen peroxide or an N-oxide mediator.

11. The process of claim 2, wherein the oxidation of 5-hydroxymethylfurfural to 5-hydroxymethyl-2-furan-carboxylic acid is carried out in an anode compartment of the electrochemical cell, said anode compartment comprising a gold-comprising anode.

12. The process of claim 2, wherein the electrochemical cell comprises an anode compartment and said anode compartment comprises an electrolyte comprising ammonium, sodium, potassium, calcium, magnesium, perchlorate, sulfate, hydrogen phosphate, a solid polymer electrolyte or a combination thereof.

13. The process of claim 2, wherein the oxidizing 5-hydroxymethylfurfural to 5-hydroxymethyl-2-furan-carboxylic acid is carried out in a solution having a pH of less than 14.

14. The process of claim 2, wherein a reduction reaction of a bio-based compound is carried out in a cathode compartment of the electrochemical cell.

15. The process of claim 16, wherein the bio-based compound is selected from the group consisting of ethanedioic acid, propanedioic acid, butanedioic acid, pentanedioic acid, hexanedioic acid, heptanedioic acid and combinations thereof.

16. The process of claim 2, wherein the oxidation of 5-hydroxymethylfurfural to 5-hydroxymethyl-2-furan-carboxylic acid is carried out in a cathode compartment of the electrochemical cell using a mediator.

17. The process of claim 18, wherein the mediator is hydrogen peroxide or an N-oxide mediator.

18. The process of claim 2, wherein a reduction is carried out in a cathode compartment of the electrochemical cell, said reduction reaction comprising generating hydrogen gas.

Description

EXAMPLE 1

Electrochemical Oxidation of HMF to HMFCA

[0032] The electrochemical oxidation of HMF to HMFCA was performed in H-shaped 2-compartment electrochemical cell consisting of two compartments, for anolyte and catholyte, separated with an anion exchange membrane. The anolyte comprised 0.01 M HMF dissolved in 100 ml aqueous buffer of 0.1 M Na.sub.2HPO.sub.4 (pH 12) and 0.1 M NaClO.sub.4, whereas catholyte consisted of 100 ml aqueous 0.1 M NaClO.sub.4. Both electrolytes were vortexed during the conversion and purged with nitrogen. A gold wire (12 cm.sup.2) was used as anode or working electrode (WE) for the oxidation reaction, HMF to HMFCA, platinum gauze was used as a cathode or counter electrode (CE) for the reduction reaction, water reduction to hydrogen and hydroxide-ion.

[0033] Prior to the experiments both of the electrodes are washed with a hot water, rinsed with ethanol, acetone and finally demi-water. SCE electrode was used as a reference electrode to control potential at the working electrode. All there electrodes were connected to a potentiostat for the control of the potential at the working electrode. For the conversion reaction following oxidation pulsed potential method was applied, where first pulse of 1 V vs SCE for duration of 1 s is applied to clean the surface of the anode, and second following pulse of 0.15 V vs SCE for duration of 30 s for the oxidation of HMF. These pulses were applied continuously for 14 hours. After the conversion the anolyte content is measured with HPLC and it is taken for the HMFCA extraction. Good conversions and high purities of HMFCA were obtained, as illustrated in FIG. 1. For instance, an isolated yield of HMFCA of more than 92 mol % based on the starting amount of HMF having a purity of 95 wt.% or more can be obtained. A decomposition of less than 5 wt % HMF was observed.

COMPARATIVE EXAMPLE 1

Direct Oxidation to of HMF to FDCA

[0034] The electrochemical oxidation of HMF to FDCA was performed in a similar setup a described in Example 1, with the difference that Ni/NiOOH was used as an anode or the WE and that the anolyte comprised 0.005 M HMF dissolved in the aqueous buffer. The reaction was carried out up to 24h. Although good a conversion of HMF was obtained, a complex mixture of reaction products was observed as illustrated in FIG. 2. The mixture included about FDCA (in a yield of about 60 mol %) together with 2-formyl-5-furancarboxylic acid (FFCA), 2,5-diformylfuran (DFF) and HMFCA. A decomposition of HMF in the range of about 10 to 15 wt% was observed, which is higher than that in Example 1.

EXAMPLE 2

TEMPO-Mediated Oxidation of HMF to FDCA in Cathode Compartment

[0035] The TEMPO-mediated oxidation of HMF to FDCA was performed in H-shaped 2-compartment electrochemical cell consisting of two compartments, for anolyte and catholyte, separated with an anion exchange membrane. The catholyte comprised 0.01 M TEMPO, 0.01 M HMF dissolved in 100 ml aqueous buffer of 0.5 M boric acid (pH 9) and 0.3 M NaClO.sub.4, whereas anolyte can comprise 100 nil aqueous 0.1 M NaClO.sub.4. Both electrolytes were vortexed during the conversion and purged with nitrogen. A gold wire (12 cm.sup.2) was used as the anode or working electrode (WE) for the oxidation reaction. Pt wire was used as a cathode or counter electrode (CE).

[0036] Prior to the experiments both of the electrodes are washed with a hot water, rinsed with ethanol, acetone and finally demi-water. SCE electrode was used as a reference electrode to control potential at the working electrode. All there electrodes were connected to a potentiostat for the control of the potential at the working electrode. For the oxidation of TEMPO, a potential of 0.75 V vs SCE was applied. The conversion of the catholyte content is measured with HPLC and FDCA was isolated. Good conversions and high purities of FDCA were obtained, as illustrated in FIG. 3. For instance, an isolated yield of FDCA of about 99 mol % based on the starting amount of HMF having a purity of 95 wt.% or more can be obtained. A decomposition of less than 2 wt% HMF was observed.

EXAMPLE 3

TEMPO-Mediated Oxidation of HMFCA to FDCA

[0037] The TEMPO-mediated oxidation of HMFCA to FDCA can be carried out similarly as described in Example 2. That is, anode compartment of an H-shaped 2-compartment electrochemical cell consisting of two compartments, for anolyte and catholyte, separated with an anion exchange membrane can be charged with 0.01 M TEMPO, 0.01 M HMFCA dissolved in 100 ml aqueous buffer of 0.5 M boric acid (pH 9) and 0.3 M NaClO.sub.4, whereas the catholyte can comprise 100 nil aqueous 0.1 M NaClO.sub.4. Both electrolytes were vortexed during the conversion and purged with nitrogen. A gold wire (12 cm.sup.2) was used as the cathode or working electrode (WE) for the oxidation reaction. A clean reaction to FDCA can be observed, in accordance with Example 2, with even less decomposition since HMF is not present. Thus overall, the two-step process shows less HMF decomposition and less production of other undesired side-products.