A method of preparing metal hydroxides from industrial wastes or alkaline rocks is provided. The method comprise subjecting a mixture comprising a solvent and a solid substrate to a stimulus in order to leach a metal cation from the solid substrate into the solvent, thereby forming a solution comprising the metal cation in the solvent; and contacting the solution of comprising the metal cation with a cathode, thereby electrolytically precipitating the metal hydroxide from the solution. The stimulus may be chemical, mechanical, or both.

There is provided a hydrogen gas mixing device that includes a hydrogen generation part configured to generate a hydrogen gas; a mixing gas supply part configured to supply a mixing gas; a gas mixing part configured to mix the hydrogen gas and the mixing gas; a dilution gas supply part configured to supply a non-combustible dilution gas; and a valve circuit configured to, at an abnormality occurrence time, dilute the hydrogen gas with the dilution gas by connecting a first path for the hydrogen gas supplied from the hydrogen generation part and a second path for the dilution gas supplied from the dilution gas supply part.

A device for converting biomass into a redox mediator in reduced form, including an assembly of microbial fuel cells including a first compartment including an anode and fermentative microorganisms and electroactive microorganisms, and a second compartment including a cathode and a solution including the mediator, and an external resistor connecting the cathode and the anode. The value of the external resistance of at least one microbial fuel cell is distinct from that of at least one other microbial fuel cell. The device thus makes it possible to induce segregation of fermentative microorganisms and electroactive microorganisms along the assembly.

A multi-channel alkaline hydrogen production system is disclosed. Using liquid outlets of a hydrogen alkali treatment unit and an oxygen alkali treatment unit, a circulating alkaline liquid is outputted to an alkaline liquid circulating pump and a controllable channel, and then the circulating alkaline liquid is returned to the negative electrode of an electrolyzer; Thus, a controller can control the amount of produced hydrogen according to the measured current of the electrolyzer, then calculates a corresponding alkaline liquid circulation volume reference value according to the amount of produced hydrogen, and according to the alkaline liquid circulation volume reference value, adjusts the circulation amount of the alkaline liquid of the multi-channel alkaline hydrogen production system and changes the gas purity of the multi-channel alkaline hydrogen production system by controlling the working states of the controllable channels on the two ends of the alkaline liquid circulating pump.

In a method for supplying oxygen-enriched gas to an oxygen consuming process, in which the oxygen-enriched gas with a low nitrogen content is generated by supplying an anode-side feed gas comprising CO.sub.2 to the anode side of a solid oxide electrolysis cell, oxygen is generated on the anode side of the solid oxide electrolysis cell. This way, an anode-side product gas is formed, in which the oxygen-enriched gas comprises at least a part. The oxygen-enriched gas has a low nitrogen content, and the temperature of the oxygen-enriched gas exiting the solid oxide electrolysis cell is between 600 and 1000° C. The method has multiple advantages, first of all as regards energy saving.

The invention relates to an electrolysis arrangement for the electrochemical production of hydrogen and oxygen from an alkaline electrolyte having anode and cathode separators for the separation of oxygen and hydrogen from the electrolyte, and an anode and cathode pipe system to circulate electrolyte between anode and cathode sections of an electrolysis stack of the electrolysis arrangement. Control valves and interconnections are configured so that dependent on an electrolyte flow rate passing first, second and third control valve, oxygen and hydrogen depleted electrolyte withdrawn from the separators can be supplied unmixed, partly mixed or fully mixed to the anode and cathode sections of the electrolysis stack to control hydrogen to oxygen and oxygen to hydrogen crossover in the electrolysis arrangement.

The invention relates to an electrolysis arrangement for the production of hydrogen and oxygen by alkaline electrolysis. The electrolysis arrangement includes a system configuration which enables to balance the lye concentrations between the anode and cathode section of the arrangement depending on the current density of the direct current supplied to the electrolysis stack of the electrolysis medium. At high current densities, hydrogen to oxygen crossover and oxygen to hydrogen crossover is low, which allows full mixing of electrolysis media to balance the concentration between anolyte and catholyte. At low current densities, hydrogen to oxygen crossover and oxygen to hydrogen crossover is high. Therefore, the electrolysis arrangement is configured so that the mixing of the electrolysis media is decreased in case a current density of a direct current supplied to the electrolysis stack is decreased.

The invention relates to a method for producing a gas product containing oxygen, wherein a feedstock containing water is subjected to electrolysis to obtain a raw anode gas, which is rich in oxygen and contains hydrogen, and a raw cathode gas, which is low in oxygen and rich in hydrogen. The raw anode gas is at least partially subjected to a catalytic conversion of hydrogen to water to obtain a first mixture with depleted hydrogen content. A first part of the first mixture is returned to the raw anode gas downstream of the electrolysis and upstream of the catalytic conversion, and the gas product containing oxygen is formed using at least a second part of the first mixture. The invention also relates to a plant for carrying out a method of this type.

A method for electrochemical hydrogen compression. The method includes: providing hydrogen gas having a relative humidity RH of 100%; providing inert gas having a relative humidity RH of 100%; mixing the humidified hydrogen gas and the humidified inert gas; electrochemically oxidizing the hydrogen gas at an anode; transporting the protons obtained as a result of the oxidation and at least a portion of the humidified inert gas through a membrane; and electrochemically reducing the protons at a cathode into hydrogen.

A fuel producing system includes an electrolyzer that is supplied with a raw material gas containing carbon dioxide and water vapor, and electrolyzes the raw material gas to generate a product gas containing hydrogen and carbon monoxide, and a first gas-liquid separator that performs gas-liquid separation on the product gas generated in the electrolyzer. Water vapor produced from water separated in the first gas-liquid separator or water vapor produced from water from a water supply source is allowed to be supplied to the electrolyzer in addition to the raw material gas.