Hydrogen generator

Patent metadata

Field	Value
Publication number	US-11447879-B2
Application number	US-201816626728-A
Country	US
Kind code	B2
Filing date	Jun 26, 2018
Priority date	Jun 27, 2017
Publication date	Sep 20, 2022
Grant date	Sep 20, 2022

Abstract

The disclosure relates to an electrolysis cell for producing hydrogen. The cell comprises an electrolyte compartment and an electrolyte disposed therein. The electrolyte comprises an aqueous alkaline solution comprising a transition metal ion or p block metal ion. The cell further comprises first and second spaced apart electrodes at least partially disposed in the electrolyte.

First claim

The invention claimed is:

1. An electrolysis cell for producing hydrogen, the cell comprising an electrolyte compartment; an electrolyte disposed in the electrolyte compartment, wherein the electrolyte comprises an aqueous alkaline solution comprising an alkali metal hydroxide or an alkaline earth metal hydroxide and a zinc ion; first and second spaced apart electrodes at least partially disposed in the electrolyte, wherein at least one of the electrodes comprises at least a layer of zinc metal; and a power supply configured to apply a voltage across the first and second electrodes, wherein (a) the power supply is configured to supply a direct current to the electrodes and the cell comprises a control system configured to monitor the current flowing through the electrodes and to switch the direction of the current if it detects that the current has fallen below a predetermined level, or (b) the power supply is configured to apply a continuous alternating or oscillating current to the electrodes.

2. The electrolysis cell according to claim 1 , wherein the first and second electrodes comprise graphite, chromium, nickel, zinc, cadmium, copper, tin, lead, rhodium, platinum, gold, palladium, iridium, osmium, rhenium, ruthenium, germanium, beryllium, silver, brass, and/or bronze.

3. The electrolysis cell according to claim 1 , wherein the alkali metal or alkaline earth metal hydroxide is from the group consisting of potassium hydroxide, sodium hydroxide, barium hydroxide, caesium hydroxide, strontium hydroxide, calcium hydroxide, lithium hydroxide, and rubidium hydroxide, optionally wherein the ratio of the hydroxide concentration to the zinc ion concentration is between 2:1 and 50:1, between 3:1 and 40:1, between 4:1 and 30:1, between 5:1 and 25:1, or between 10:1 and 20:1.

4. The electrolysis cell according to claim 3 , wherein the alkali metal or alkaline earth metal hydroxide is sodium hydroxide and the ratio of hydroxide concentration to the zinc ion concentration is between 10:1 and 15:1.

5. The electrolysis cell according to claim 3 , wherein the alkali metal or alkaline earth metal hydroxide is potassium hydroxide and the ratio of hydroxide concentration to the zinc ion concentration is between 15:1 and 20:1.

6. The electrolysis cell according to claim 1 , wherein the pH of the aqueous alkaline solution at 20° C. is at least 9, at least 10, at least 11 or at least 11.5 and/or wherein the concentration of the zinc ion in the electrolyte is between 0.01 M and 1.2 M, between 0.05 M and 1 M, between 0.1 M and 0.8 M, between 0.15 M and 0.6 M, or between 0.2 M and 0.4 M.

7. The electrolysis cell according to claim 1 , wherein the electrolyte comprises sodium zincate and the concentration of the zinc ion is between 0.01 M and 0.6 M, between 0.1 M and 0.4 M, between 0.15 M and 0.3 M, or between 0.2 M and 0.25 M.

8. The electrolysis cell according to claim 1 , wherein the electrolyte comprises potassium zincate and the concentration of the zinc ion is between 0.01 M and 1.2 M, between 0.1 M and 0.6 M, between 0.2 M and 0.5 M, or between 0.25 M and 0.45 M.

9. The electrolysis cell according to claim 1 , wherein the power supply is configured to apply a voltage of between 1 V and 6 V, between 1.5 V and 3 V, or between 2 and 2.5 V.

10. An apparatus for generating and storing hydrogen, the apparatus comprising the electrolysis cell of claim 1 , a chamber for hydrogen gas storage, and a conduit configured to feed hydrogen gas from the cell to the chamber.

11. The apparatus according to claim 10 , wherein the chamber comprises:
a first portion comprising a first gas;
a second portion comprising a second gas; and
a liquid,

wherein the chamber is configured to allow the liquid to flow between the first and second portions and to prevent the first gas in the first portion from exchanging with the second gas in the second portion.

12. The apparatus according to claim 11 , wherein the first portion of the chamber comprises an outlet comprising a valve, optionally wherein the valve comprises a back-pressure regulating valve.

13. A method of producing hydrogen, the method comprising:
providing an electrolysis cell, the electrolysis cell comprising:
an electrolyte compartment;
an electrolyte disposed in the electrolyte compartment, wherein the electrolyte comprises an aqueous alkaline solution comprising an alkali metal hydroxide or an alkaline earth metal hydroxide and a zinc ion;
two electrodes, wherein the electrodes comprise a cathode and a spaced apart anode and are at least partially disposed in the electrolyte and the anode comprises at least a layer of zinc metal; and
applying a voltage across the two electrodes characterised in that the method comprises applying a continuous alternating or oscillating current to the electrodes or monitoring the rate of hydrogen production and/or the current and switching the direction of the current supplied to the electrodes when a drop in the rate of hydrogen production and/or the current is observed.

14. The method according to claim 13 , wherein the method comprises—applying a voltage across the two electrodes, thereby causing a layer of the zinc metal to form on the cathode; and
switching the direction of the current supplied to the electrodes to provide the electrolysis cell with an anode comprising the layer of the zinc metal.

15. The method according to claim 13 , wherein the method comprises adding water to the electrolyte to maintain the concentration of the zinc ion dissolved therein.

16. The electrolysis cell according to claim 1 , wherein the power supply is configured to supply a direct current to the electrodes and the cell comprises a control system configured to monitor the current flowing through the electrodes and to switch the direction of the current if it detects that the current has fallen below a predetermined level.

17. The electrolysis cell according to claim 1 , wherein the power supply is configured to apply a continuous alternating or oscillating current to the electrodes.

18. The electrolysis cell according to claim 17 , wherein the power supply is configured to apply the continuous alternating or oscillating current in the form of a sine wave, triangle wave, sawtooth wave or square wave.

19. The electrolysis cell according to claim 17 , wherein the power supply is configured to apply the continuous alternating or oscillating current at between 0.01 Hz and 100 Hz.

20. The electrolysis cell according to claim 19 , wherein the power supply is configured to apply the continuous alternating or oscillating current in the form of a sine wave.

Assignees

• Univ Surrey

Inventors

• Amini Horri Bahman
• Gu sai

Classifications

• C25B15/023

  Measuring, analysing or testing during electrolytic production · CPC title

• C25B15/02

  Process control or regulation · CPC title

• C25B9/17

  Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof · CPC title

• C25B11/075

  consisting of a single catalytic element or catalytic compound · CPC title

• C25B1/04 Primary

  by electrolysis of water · CPC title