GAS DIFFUSION LAYER FOR ELECTROCHEMICALLY CONVERTING GAS

Abstract

The invention is directed to a process for electrochemically converting a reactant gas, to an electrolyser, to a gas diffusion electrode, to a method for producing a gas diffusion electrode, to a gas diffusion layer, and to the use of said gas diffusion layer and/or gas diffusion electrode.

The process comprises reacting a reactant gas at a gas diffusion electrode to form a product gas and/or a liquid product,

wherein the gas diffusion electrode comprises a gas diffusion layer comprising a non-porous layer that is permeable to carbon monoxide and/or carbon dioxide gas, and a porous layer, and
the reactant gas comprises carbon monoxide and/or carbon dioxide.

Claims

1. A process for electrochemically converting a reactant gas, the process comprising reacting a reactant gas at a gas diffusion electrode to form one or more of a product gas and a liquid product, wherein the gas diffusion electrode comprises a gas diffusion layer comprising a non-porous layer that is permeable to carbon monoxide and/or carbon dioxide gas, and a porous layer, and the reactant gas comprises one or more of carbon monoxide and carbon dioxide.

2. The process of claim 1, comprising introducing the reactant gas into a cathode compartment of an electrochemical cell.

3. The process of claim 2, wherein the reactant gas is introduced into a gas compartment of the cathode compartment, the gas compartment being separated from a catholyte compartment by the gas diffusion electrode.

4. The process of claim 2, wherein the gas diffusion electrode separates the cathode compartment from an anode compartment of the electrochemical cell.

5. The process of claim 2, further comprising collecting one or more of the product gas and the liquid product from the cathode compartment.

6. The process of claim 2, wherein an absolute pressure in the electrochemical cell is 20 bar or more.

7. The process of claim 1, wherein the gas diffusion electrode further comprises a catalyst layer.

8. The process of claim 7, wherein the catalyst layer is on the porous layer of the gas diffusion layer, or on the non-porous layer of the gas diffusion layer.

9. The process of claim 7, wherein the catalyst layer comprises a catalytic material and a conductive material.

10. The process of claim 9, wherein the conductive material is integrated in the catalytic material or is present as a separate layer.

11. The process of claim 1, wherein the non-porous layer is a non-porous, polymeric layer and the porous layer is a porous, polymeric layer.

12. The process of claim 1, wherein the non-porous layer has a coefficient for permeability to one or more of carbon monoxide gas and carbon dioxide gas of 1×10.sup.2 to 1×10.sup.5 Barrer.

13. The process of claim 1, wherein the non-porous layer has a thickness in the range of from 0.1 μm to 10 μm.

14. The process of claim 1, wherein the porous layer has a thickness in the range of from 1 μm to 5 μm.

15. An electrolyser, comprising a gas diffusion electrode as defined in claim 1.

16. The electrolyser of claim 15, comprising an anode compartment and a cathode compartment, wherein the cathode compartment comprises the gas diffusion electrode, or the gas diffusion electrode separates the anode compartment from the cathode compartment.

17. A gas diffusion electrode as defined in claim 1.

18. A method for producing a gas diffusion electrode comprising: providing a gas diffusion layer according to claim 1, coating a catalytic layer on the non-porous layer or on the porous layer of the gas diffusion layer.

19. The method of claim 18, wherein the gas diffusion electrode comprises a gas diffusion layer comprising a non-porous layer that is permeable to carbon monoxide and/or carbon dioxide gas, and a porous layer.

20. The method of claim 18, further comprising coating the gas diffusion layer with an electroconductive material.

21. The method of claim 20, wherein the electroconductive material comprises electroconductive particles.

22. A gas diffusion layer as defined in claim 1.

23. The process of claim 1 wherein the process results in an electrochemical conversion of a gaseous reactant in a liquid electrolyte.

24. The process of claim 23, wherein the electrochemical conversion is the electrochemical conversion of one or more of carbon monoxide and carbon dioxide.

Description

EXAMPLE

[0072] A two-compartment electrochemical reactor was used for electrochemically converting carbon dioxide to formic acid using gas diffusion electrodes based on the gas diffusion layer of the invention (dense asymmetric PTMSP membrane). The reactor consisted of a platinum plate anode (10 cm.sup.2) and a tin-based gas diffusion electrode (10 cm.sup.2), prepared by coating a PTMSP asymmetric membrane with a dispersion of carbon nanotubes+Nafion®, until a resistivity of about 22 ohm was obtained, at 7.7 mg/cm.sup.2. Tin nanoparticles were then sprayed on the surface, obtaining a loading of 2.7 mg/cm.sup.2. Electrolytes used: anolyte 0.5 M H.sub.2SO.sub.4 (250 ml), and catholyte: 1.0 M KHCO.sub.3 (250 ml).

[0073] Chronopotentiometry testing was performed at −1 A (−100 mA/cm.sup.2) (FIG. 2A). Cathode potential and anode potentials were measured and reported in volts (V) versus Ag/AgCl. Cell potential was measured and reported in volts (V). Cathode potential stabilised at about −2.8 V versus Ag/AgCl, and anode potential around about 2.05 V versus Ag/AgCl, during electrolysis. Faraday efficiency of 40-50% towards target, formic acid molecule, was obtained during electrochemical conversion of carbon dioxide on custom made gas diffusion electrode with a dense membrane layer to prevent flooding (FIG. 2B). No flooding was observed during electrolysis.