# US 2021/0340681 A1 · Electrochemical system, apparatus and method to generate metal hydroxide in the presence of metal silicates

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- Number: US 2021/0340681 A1
- Document ID: US20210340681A1
- Status: Published application
- Kind: A1
- Application number: 17/243,499
- Filed: 2021-04-28
- Published: 2021-11-04
- Earliest claimed: 2020-04-29
- Assignees: Planetary Hydrogen Inc.
- Applicants: Planetary Hydrogen Inc.
- Inventors: Gregory Hudson Rau; Sadaf Tahmasebi; Clive Mervyn Hugh Brereton; Alexandru Vasile Mezei; Michael John Kelland
- Web page: https://patentgrep.com/patent/US20210340681A1

## CPC

- C25B 9/23: comprising ion-exchange membranes in or on which electrode material is embedded
- B01D 53/62: Carbon oxides
- C25B 1/02: Hydrogen or oxygen
- C25B 1/20: Hydroxides
- C25B 1/50: Processes
- C25B 9/21: two or more diaphragms
- C25B 9/65: Means for supplying current; Electrode connections; Electric inter-cell connections
- C25B 15/081: {Supplying products to non-electrochemical reactors that are combined with the electrochemical cell, e.g. Sabatier reactor}
- C25B 15/083: {Separating products}
- C25B 15/085: {Removing impurities}
- C25B 15/087: {Recycling of electrolyte to electrochemical cell}
- B01D 2251/604: Hydroxides
- B01D 2257/302: Sulfur oxides
- B01D 2257/304: Hydrogen sulfide
- B01D 2257/402: Dinitrogen oxide
- B01D 2257/504: Carbon dioxide
- Y02C 20/10: of nitrous oxide (N2O)
- Y02E 60/36: Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
- Y02P 20/133: Renewable energy sources, e.g. sunlight
- Y02P 20/151: Reduction of greenhouse gas [GHG] emissions, e.g. CO2
- C25B: ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR (anodic or cathodic protection C23F13/00; single-crystal growth C30B)
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

An apparatus and method are provided for the electrochemical production of hydrogen, oxygen and metal hydroxide wherein the metal is derived from a metal silicate. The process involves the electrolysis of a metal salt solution where hydrogen and a metal hydroxide are produced at the cathode, and oxygen, or chlorine, and an acid are produced at the anode. The acid is reacted with a metal silicate producing a soluble metal salt and water that is used in turn to make solid or dissolved metal hydroxide. The net CO2 and acid gas emissions of the invention and its products may therefore be significantly reduced or turned negative.

## Claims

### Claim 1

An apparatus for electrochemically generating metal hydroxide, oxygen and hydrogen, the apparatus comprising:
an electrolytic container having an anode, a cathode, a direct current source connected to the anode and the cathode, an electrolytic solution comprising a metal salt, the electrolytic solution disposed in said electrolytic container to undergo electrolysis when a direct current is applied, at least one ion-exchange membrane disposed in said electrolytic container between said anode and said cathode and defining a cathode region and an anode region;
a second container disposed externally to said electrolytic container for holding a quantity of a solid metal silicate material, the second container being in fluid communication with said electrolytic container;
means for supplying acidic solution from the anode region to said second container to effect dissolution of said solid metal silicate material and to generate a metal salt solution, wherein the solid metal silicate material, the acidic solution, and the electrolytic solution have been chosen so that:
(i) the metal in the solid silicate material and the metal in said metal salt are the same; and
(ii) the metal salt solution and the electrolytic solution contain said metal salt;
means for supplying the metal salt solution from said second container to said electrolytic container.

### Claim 2 (depends on 1)

The apparatus of claim 1 further comprising purification means configured to purify said metal salt solution, before passing the purified metal salt solution from said second container to said electrolytic container.

### Claim 3 (depends on 2)

The apparatus of claim 2, wherein the purification unit is configured to remove silica and other compounds from said metal salt solution, the unit being disposed between said second container and said electrolytic container.

### Claim 4 (depends on 1)

The apparatus of claim 1, comprising a cation exchange membrane and an anion exchange membrane disposed in said electrolytic container between said anode and said cathode and defining an anode region, a cathode region and a central region therebetween.

### Claim 5 (depends on 1)

The apparatus of claim 1, further comprising means for removing gaseous and liquid products from the electrolytic container.

### Claim 6 (depends on 1)

The apparatus from claim 1, further comprising means for removing and storing the metal hydroxide.

### Claim 7 (depends on 1)

The apparatus of claim 1 where said solid metal silicate is magnesium silicate.

### Claim 8 (depends on 1)

The apparatus of claim 1, further comprising means for removing an acid gas from air or a gas volume using said metal hydroxide.

### Claim 9 (depends on 7)

The apparatus of claim 7, wherein the acid gas is carbon dioxide.

### Claim 10

A method of generating hydrogen, an oxidative gas and a metal hydroxide for sequestering gaseous carbon dioxide or other acid gases, the method comprising the steps of:
(a) supplying a direct current from an electrical source at a predetermined voltage to an electrolytic container having an anode, a cathode, an electrolyte solution comprising a metal salt, an anode region adapted to generate the oxidative gas and an acidic solution, and a cathode region adapted to generate hydrogen gas and a dissolved metal hydroxide solution, the metal in said dissolved metal hydroxide solution being derived from the electrolyte solution;
(b) supplying, from a source disposed externally to the electrolytic container, a metal silicate soluble in the acidic solution;
(c) removing the acidic solution from the anode region to another container outside the electrolytic container, for reacting the removed acidic solution with the metal silicate to generate a metal salt solution, wherein the metal is derived from the metal silicate;
(d) reacting the metal salt solution from the step (c) with the dissolved metal hydroxide solution of the step (a) to produce a reaction solution and generate another metal hydroxide, wherein the metal in said another metal hydroxide is derived from the metal silicate;
(e) separating said another metal hydroxide from the remaining reaction solution in the step (d); and
(f) supplying the remaining reaction solution back to the electrolytic container for use as the electrolyte solution.

### Claim 11 (depends on 10)

The method of claim 10, further comprising purifying the metal salt solution after the step (c).

### Claim 12 (depends on 10)

The method of claim 10, wherein:
the step (a) comprises providing the electrolyte solution comprising a soluble monovalent metal salt; and
the step (c) comprises generating the metal salt solution predominantly comprising one or more metals having valency of two or higher.

### Claim 13 (depends on 12)

The method of claim 12, wherein:
the soluble monovalent metal salt contains ions of Na or K; and
the metal derived from the metal silicate is one or more selected from the group consisting of Mg, Ca, Fe, and Cr.

### Claim 14 (depends on 10)

The method of claim 10 wherein the metal silicate comprises magnesium silicate.

### Claim 15 (depends on 10)

The method of claim 10, wherein the steps (d) and (e) are conducted in a reactor vessel externally to the electrolytic container.

### Claim 16 (depends on 10)

The method of claim 10, wherein said metal hydroxide in the step (e) is solid metal hydroxide.

### Claim 17 (depends on 10)

The method of claim 10, wherein said metal hydroxide in the step (e) is solid magnesium hydroxide.

### Claim 18 (depends on 10)

The method of claim 10, further comprising using said metal hydroxide for removing an acid gas from air or a gas volume.

### Claim 19 (depends on 18)

The method of claim 18, wherein the acid gas is carbon dioxide.

### Claim 20 (depends on 10)

The method of claim 10, further comprising using a cation exchange membrane and an anion exchange membrane, for defining the anode region, the cathode region and a central region of the electrolytic container.

### Claim 21

An apparatus for electrochemically generating metal hydroxide, oxygen and hydrogen, the apparatus comprising:
an electrolytic container having an anode, a cathode, a direct current source connected to the anode and the cathode, an electrolyte solution disposed in said electrolytic container to undergo electrolysis when the direct current is applied, two ion-exchange membranes disposed in said electrolytic container between said anode and said cathode and defining a cathode region, an anode region and a central region between said anode region and said cathode region;
a second container disposed externally to said electrolytic container for holding a quantity of a solid metal silicate material, the second container being in fluid communication with said electrolytic container;
means for supplying acidic solution from the anode region to said second container to effect dissolution of said solid mineral silicate material and to generate a metal salt solution wherein the metal is derived from said solid metal silicate material;
purification means configured to purify said metal salt solution;
a hydroxide reactor in fluid communication with said electrolytic container, for precipitating low-solubility metal hydroxides whose metal is derived from the dissolution of the solid metal silicate material; and
a filtering unit connected to the hydroxide reactor and configured for separating the low-solubility precipitate from a solution removed from the hydroxide reactor.