The historical development, current status and future prospects of chlor-alkali electrolysis with oxygen depolarized cathodes (ODCs) are summarized. Over the last decades, membrane chlor-alkali technology has been optimized to such an extent that no substantial reduction of the energy demand can be expected from further process modifications. However, replacement of the hydrogen evolving cathodes in the classical membrane cells by ODCs allows for reduction of the cell voltage and correspondingly the energy consumption of up to 30%. This replacement requires the development of appropriate cathode materials and novel electrolysis cell designs. Due to their superior long-term stability, ODCs based on silver catalysts are very promising for oxygen reduction in concentrated NaOH solutions. Finite-gap falling film cells appear to be the technically most mature design among the several ODC electrolysis cells that have been investigated.

Chlor-alkali electrolysis with oxygen depolarized cathodes: history, present status and future prospects

A sensing device includes a propulsion system that is typically substantially or completely within the sensing device. The propulsion system may include, for example, a rotatable propeller. The sensing device may be an in-vivo autonomous capsule with an imager, but may be another type of sensing device.

Self propelled device

A porous structure having a plurality of bonded sheets each sheet having at least one aperture that partially overlaps an aperture of at least one other sheet. A method of producing a porous structure including stacking a plurality of sheets each sheet having a multiplicity of apertures, and bonding each sheet to its adjoining sheet. An open-pore network structure having a multiplicity of sheets each having a repeatable pattern. At least a portion of each sheet is bonded to the web of an adjacent sheet. The porous area of at least one of the sheets is askew to the porous area of at least another of the sheets. An open-pore structure having a multiplicity of bonded sheets, each sheet having a repeatable pattern defining a multiplicity of perforations, and a plurality of apertures defined by the repeatable pattern, the apertures extending through the perforations of at least two adjacent plates.

Assembled non-random foams

A particularly inexpensive, homogeneous and porous gas diffusion electrode is produced with at least one electrically conducting water-repellent and gas-permeable gas diffusion layer containing a mechanically stable support material impregnated with at least one electrically conducting material of bulk conductivity equal too or in excess of 10 mS/cm. The gas diffusion electrode can be coated with a catalytically active layer. The claimed electrodes are especially suitable for use in fuel or electrolysis cells.

Gas diffusion electrode for polymer electrolyte membrane fuel cells

A sensing device includes a magnetohydrodynamic propulsion system. The sensing device may be an in-vivo autonomous capsule with an imager, but may be another type of sensing device.

Self propelled device having a magnetohydrodynamic propulsion system

An electrolytic cell for obtaining a caustic alkali by closely contacting a gas diffusion electrode comprising a gas-liquid permeable metal substrate and a gas-liquid permeable collector connected to the substrate to a cation-exchange membrane while supplying an oxygen-containing gas from the opposite side of the cation-exchange membrane. Grooves for taking out a liquid containing a caustic alkali are formed in the contact surface of the gas diffusion electrode with the cation-exchange membrane. By the formation of the grooves, clogging of the perforations of the gas diffusion electrode with the caustic alkali so formed is prevented, whereby the gas supply can be smoothly carried out and the electrolysis can be stably carried out without reducing the cell voltage.

Electrolytic cell using gas diffusion electrode

Electrolysis is carried out while supplying an aqueous sodium chloride solution having a weak acidic property to the anode chamber of a water electrolytic cell The electrolytic cell is partitioned with a cation-exchange membrane into an anode chamber and a cathode chamber Furthermore, because the pH of the anolyte is sufficiently reduced due to the acid content and pH of the liquid supplied to the anode chamber from the start of electrolysis, which is different from a conventional electrolytic method, the electrolysis of the present invention may be carried out for a time needed to obtain a sufficiently high oxidation reduction potential Thus, acid water almost the same as that obtained in a conventional method is obtained in the present invention by consuming about {fraction (1/10)} the electric power that is used in a conventional method

Production method of acid water and alkaline water

The electrolytic cell 1 for producing alkali hydroxide or hydrogen peroxide is divided into the anode compartment 3 and the cathode compartment 4 by the cation exchange membrane 2. The cathode compartment 4 is further divided by the anion exchange membrane 6 into the solution compartment 7 containing a concentrated aqueous solution of alkali hydroxide and the gas compartment accommodating the gas cathode 8. The anion exchange membrane 6 prevents the gas cathode 8 from coming into direct or indirect contact with the aqueous solution of alkali hydroxide. This leads to the extended life of the gas cathode. The above-mentioned arrangement is effective in large-sized electrolytic cells. Thus, the present invention can be applied to industrial electrolysis which has never been achieved with the conventional gas electrode.

Electrolytic cell and processes for producing alkali hydroxide and hydrogen peroxide

The present invention relates to an electrolytic electrode comprising a core material made of a valve metal, a dense electrically conductive tin oxide layer formed on the core material, an α-lead dioxide layer formed on the tin oxide layer, and a β-lead dioxide layer formed on the α-lead dioxide layer. The present invention also relates to a method for preparing the electrolytic electrode.

Electrolytic electrode and method of production thereof

A method of producing a gas diffusion electrode by forming a thin layer comprising a carbon power and a silver powder on the surface of a substrate comprising silver, copper, nickel or stainless steel and fluorinating the thin layer make the carbon water repellent. The gas diffusion electrode can be stably used for a long period of time in sodium chloride electrolysis, etc., without clogging the passage of gas and lowering the water repellency of the electrode.

Yasuo Nakajima

Papers

Electrolytic cell using gas diffusion electrode

Production method of acid water and alkaline water

Electrolytic cell and processes for producing alkali hydroxide and hydrogen peroxide

Electrolytic electrode and method of production thereof

Method of producing gas diffusion electrode