Abstract: Chlorine is generated by electrolyzing aqueous alkali metal chloride in a cell wherein the anode and cathode are separated by and in contact with an ion exchange diaphragm and wherein the anode and/or cathode contains particles of an electroconductive catalytic material along with particles of an electroconductive extender bonded to the membrane.

Abstract: A halogen, such as chlorine, is generated by electrolysis of an aqueous solution of an alkali metal halide such as sodium chloride, in a cell having anolyte and catholyte chambers separated by a solid polymer electrolyte in the form of a stable, selectively cation permeable, ion exchange membrane. One or more catalytic electrodes including at least one thermally stablized, reduced oxide of a platinum group metal are bonded to the surface of the membrane. An aqueous brine solution is brought into contact with the anode and water or an aqueous NaOH solution is brought into contact with the cathode. The brine is electrolyzed to produce chlorine at the anode and hydrogen and caustic at the cathode. The cell membrane preferably has an anion rejecting cathode side barrier layer which rejects hydroxyl ions to block back migration of caustic to the anode thereby enhancing the cathode current efficiency of the cell and of the process.

Abstract: A gas generating apparatus and method is described which utilizes a novel catalytic oxygen evolving electrode for such electrochemical systems as electrolysis cells and oxygen concentration cells. The electrochemical cells include a catalytic cathode and an improved catalytic anode positioned on opposite sides of, and in electrical contact with, a cation exchange membrane. A source of direct current potential between the cathode and the anode and means for removing gas from at least one of the electrodes are provided. The improved catalytic anode is a ternary platinum group reduced metal oxide alone or in combination with platinum group metals and/or platinum group metal oxides or mixtures of the foregoing having at least one valve metal component such as titanium, hafnium, zirconium, niobium, tantalum and tungsten.

Abstract: A halogen, such as chlorine, is generated by electrolysis of an aqueous solution of an alkali metal halide such as sodium chloride, in a cell having anolyte and catholyte chambers separated by a solid polymer electrolyte in the form of a stable, selectively cation permeable, ion exchange membrane. One or more catalytic electrodes including at least one thermally stabilized, reduced oxide of a platinum group metal are bonded to the surface of the membrane. An aqueous brine solution is brought into contact with the anode and water or an aqueous NaOH solution is brought into contact with the cathode. The brine is electrolyzed to produce chlorine at the anode and hydrogen and caustic at the cathode. The cell membrane preferably has an anion rejecting cathode side barrier layer which rejects hydroxyl ions to block back migration of caustic to the anode thereby enhancing the cathode current efficiency of the cell and of the process.

Abstract: A gas generating apparatus and method is described which utilizes a novel catalytic oxygen evolving electrode for such electrochemical systems as electrolysis cells and oxygen concentration cells. The electrochemical cells include a catalytic cathode and an improved catalytic anode positioned on opposite sides of, and in electrical contact with, a cation exchange membrane. A source of direct current potential between the cathode and the anode and means for removing gas from at least one of the electrodes are provided. The improved catalytic anode is a ternary platinum group reduced metal oxide alone or in combination with platinum group metals and/or platinum group metal oxides or mixtures of the foregoing having at least one valve metal component such as titanium, hafnium, zirconium, niobium, tantalum, and tungsten.

Abstract: A novel, electrocatalytic material comprising at least one reduced platinum group metal oxide is subsequently heated in the presence of oxygen at a temperature high enough to stabilize the catalyst in acidic and halogen environments. The catalyst optionally contains other thermally stabilized, reduced platinum group metal oxides, electroconductive extenders of the group consisting of graphite and oxides of transition or valve metals. A novel electrode structure includes the catalyst and a polymeric binder. A novel method of preparing the electrocatalytic material is described as well as a unitary electrolyte electrode structure which has a bonded electrode containing the novel electrocatalytic material, bonded to at least one side of a membrane-electrolyte.

Abstract: A gas generating apparatus and method is described which utilizes a novel catalytic oxygen evolving electrode for such electrochemical systems as electrolysis cells and oxygen concentration cells. The electrochemical cells include a catalytic cathode and an improved catalytic anode positioned on opposite sides of, and in electrical contact with, a cation exchange membrane. A source of direct current potential between the cathode and the anode and means for removing gas from at least one of the electrodes are provided. The improved catalytic anode is a ternary platinum group reduced metal oxide alone or in combination with platinum group metals and/or platinum group metal oxides or mixtures of the foregoing having at least one valve metal component such as titanium, hafnium, zirconium, niobium, tantalum and tungsten.

Abstract: A gas generating apparatus and method is described which utilizes a novel catalytic oxygen evolving electrode for such electrochemical systems as electrolysis cells and oxygen concentration cells. The electrochemical cells include a catalytic cathode and an improved catalytic anode positioned on opposite sides of, and in electrical contact with, a cation exchange membrane. A source of direct current potential between the cathode and the anode and means for removing gas from at least one of the electrodes are provided. The improved catalytic anode is a ternary platinum group reduced metal oxide alone or in combination with platinum group metals and/or platinum group metal oxides or mixtures of the foregoing having at least one valve metal component such as titanium, hafnium, zirconium, niobium, tantalum, and tungsten.

Abstract: A unique, current conducting bipolar separator in a cell for electrolysis of chlorides makes multiple contact with the anodes and cathodes bonded to an ion transporting membrane in an electrolysis cell. Each side of the separator plate includes a plurality of electrode contacting, current conducting ribs or projections which also define a plurality of flow channels to allow fluid transport and good flow distribution. The projections or ribs on opposite sides of the separator plates are angularly disposed relative to each other so that the membrane is supported on one side by ribs of one separator and on the other side by the ribs from another separator which are angularly disposed to the first group. The intersection of the ribs on opposite sides of the membrane, thus, establishes a plurality of pressure areas or bearing surfaces which support the membrane without deforming it and without requiring very precise registration and alignment of the ribs.

Abstract: A compact electrochemical gas sensing cell is described for detecting gases such as carbon monoxide, NO.sub.2, alcohol vapors, etc. The cell is characterized by temperature stability during zero-air operation so that background current with no gas flow is eliminated or minimized. This cell utilizes a hydrated, solid polymer electrolyte having reference, sensing and counter electrodes mounted on the surface thereof with one side of the membrane being flooded with distilled water to provide self-humidification of the cell by water vapor transport across the membrane. A potentiostatic circuit is utilized to control the potential on the sensing circuit and also to maintain a fixed potential difference between the reference and the sensing electrodes. In addition, the chemical, electrochemical, and thermal characteristics of the sensing and reference electrodes are matched so that the sensor is highly temperature invariant during zero-air operation.

Abstract: A halogen, such as chlorine, is generated by electrolysis of an aqueous solution of an alkali metal halide such as sodium chloride, in a cell having anolyte and catholyte chambers separated by a solid polymer electrolyte in the form of a stable, selectively cation permeable, ion exchange membrane. One or more catalytic electrodes including at least one thermally stabilized, reduced oxide of a platinum group metal are bonded to the surface of the membrane. An aqueous brine solution is brought into contact with the anode and water or an aqueous NaOH solution is brought into contact with the cathode. The brine is electrolyzed to produce chlorine at the anode and hydrogen and caustic at the cathode. The cell membrane preferably has an anion rejecting cathode side barrier layer which rejects hyroxyl ions to block back migration of caustic to the anode thereby enhancing the cathode current efficiency of the cell and of the process.

Abstract: A halogen such as chlorine is produced by the electrolysis of an aqueous solution of a hydrogen halide such as hydrochloric acid in an electrolysis cell having anolyte and catholyte chambers separated by a solid polymer electrolyte in the form of a stable, selectively permeable, hydrated ion exchange membrane. Catalytic electrodes in the form of fluorocarbon bonded, thermally stabilized, reduced oxides of platinum group metals are bonded to at least one surface of the membrane and an aqueous hydrochloric acid solution is brought in contact with the bonded anode to generate chlorine at the anode and hydrogen at the cathode.

Abstract: A halogen such as chlorine is generated by the electrolysis of aqueous halides in an electrolysis cell which includes an anode and a cathode separated by an ion transporting membrane. At least the cathode, which is a mass of noble metal catalytic particles and particles of a suitable binder, is bonded to the surface of the membrane. An oxygen containing gaseous stream is brought into contact with the bonded cathode to depolarize the cathode and prevent or limit discharge of hydrogen at the cathode, thereby substantially reducing the cell voltage.

Abstract: A compact electrochemical gas sensing cell is described for detecting gases which are either immediately dangerous to health such as carbon monoxide, NO.sub.2, etc., or represent a social or public welfare risk. The latter area, for example, may require determining alcohol breath content of a driver of a motor vehicle. The cell uses a hydrated, solid polymer electrolyte which has sensing and reference electrodes positioned on one side of the solid polymer electrolyte membrane and a counter electrode positioned on the other side. One side of the hydrated SPE membrane is flooded with distilled water so that incoming gases are brought to essentially 100% relative humidity by rapid vapor phase water transport across the membrane, thereby eliminating the need for external humidification in the form of bubblers and the like. An ionically conductive hydrated SPE bridge is formed on one side of the membrane and is located spatially to provide a low resistance path between the reference and sensing electrodes.