Olin Corporation

Kenneth E Woodard, Jr

David W Cawlfield

Igor V Kadija

Ronald L Dotson

Jerry J Kaczur

Budd L Duncan

David D Justice

Steven J Specht

James M Ford

Sudhir K Mendiratta

David L Fair

Robert A Dean

Han C Kuo

Julius C Fister

Byung K Ahn

Antonio Branco

Jerry J Kazcur

Morton S Kircher

Ronald C Miles

Garland E Hilliard

John O Adams

Roger E Bolick, Ii

David A Helmstetter

Paul M Waxelbaum

Charles H Harrison

Elizabeth K Muse

A process and apparatus for producing chlorine dioxide comprising chemically reducing chloric acid with water in the presence of any oxygen-evolving catalyst and in the absence of another acid or an added reducing agent, thereby producing chlorine dioxide and oxygen.

Catalytic process for chlorine dioxide generation from chloric acid

The present invention relates to an electrochemical process for the removal of excess or residual nitric acid from aqueous hydroxylammonium nitrate (HAN) solutions. The process utilizes a multi-compartment electrochemical membrane cell in which the HAN solution flows through a central ion exchanging compartment bounded by anion membranes on either side. Electrochemically generated OH-ions formed at the cathode are used to displace and remove the nitric acid from the HAN solution. In use, the residual nitric acid content in the HAN is suitably reduced to a specified safe level before the HAN is concentrated to a 13.0 molar final composition.

Electrochemical process for the removal of residual nitric acid from

A process for electrochemically treating an aqueous solution containing inorganic oxynitrogen species is disclosed in which the aqueous solution is fed into the catholyte compartment of an electrochemical reduction cell using a high surface area cathode separated from an anolyte compartment to electrochemically reduce substantially all of the oxynitrogen species to nitrogen or ammonia and produce a purified water product.

Process for the removal of oxynitrogen species for aqueous solutions

The novel process of the invention produces chlorine dioxide by feeding an aqueous solution of chloric acid to a chlorine dioxide generator. The aqueous solution of chloric acid is reacted with a reducing agent in the chlorine dioxide generator to produce chlorine dioxide and a spent chloric acid solution containing metallic impurities. A portion of the spent chloric acid solution containing metallic impurities is reacted with a basic compound selected from the group consisting of alkali metal hydroxides, and alkali metal carbonates in a neutralizing zone to form a precipitate of the metallic impurities and an alkali metal chlorate solution. The precipitate of the metallic impurities is separated from the alkali metal chlorate solution and the alkali metal chlorate solution fed to an ion exchange compartment of an electrolytic cell having an anode compartment, a cathode compartment, and at least one ion exchange compartment between the anode compartment and the cathode compartment. Electrolysis of an anolyte in the anode compartment generates hydrogen ions which pass through a cation exchange membrane into the ion exchange compartment to displace alkali metal ions and produce an aqueous solution of chloric acid and alkali metal chlorate. The aqueous solution of chloric acid and alkali metal chlorate is returned to the chlorine dioxide generator. The process of the invention produces chlorine dioxide free of chlorine from mixtures of oxy-chlorine species. A continuous removal of metallic impurities permits avoiding or significantly increasing the time period between generator shutdowns.

Effluent treatment in a process for producing chlorine dioxide from

An aqueous solution of chloric acid and alkali metal chlorate is produced in an electrolytic cell having an anode compartment, a cathode compartment, and at least one ion exchange compartment between the anode compartment and the cathode compartment. The process comprises feeding an aqueous solution of an alkali metal chlorate to the ion exchange compartment, electrolyzing an anolyte in the anode compartment to generate hydrogen ions, passing the hydrogen ions from the anode compartment through a cation exchange membrane into the ion exchange compartment to displace alkali metal ions and produce an aqueous solution of chloric acid and alkali metal chlorate, passing alkali metal ions from the ion exchange compartment into the cathode compartment, removing the aqueous solution of chloric acid and alkali metal chlorate from the ion exchange compartment, and, increasing the chlorate ion concentration to provide the aqueous solution of chloric acid and alkali metal chlorate with a total chlorate ion to water molar ratio of about 0.15 or greater.

Chloric acid - alkali metal chlorate mixtures and chlorine dioxide

An aqueous solution of chloric acid and alkali metal chlorate is produced in an electrolytic cell having an anode compartment, a cathode compartment, and at least one ion exchange compartment between the anode compartment and the cathode compartment. The process comprises feeding an aqueous solution of an alkali metal chlorate to the ion exchange compartment, electrolyzing an anolyte in the anode compartment to generate hydrogen ions, passing the hydrogen ions from the anode compartment through a cation exchange membrane into the ion exchange compartment to displace alkali metal ions and produce an aqueous solution of chloric acid and alkali metal chlorate, passing alkali metal ions from the ion exchange compartment into the cathode compartment, removing the aqueous solution of chloric acid and alkali metal chlorate from the ion exchange compartment, and reacting the aqueous solution of chloric acid and alkali metal chlorate with a strong acid having a dissociation constant of 1.times.10.sup.-4 or greater and a reducing agent to generate chlorine dioxide gas.

Electrochemical process for generating chlorine dioxide using chloric

An aqueous solution of chloric acid and alkali metal chlorate is produced in an electrolytic cell having an anode compartment, a cathode compartment, and at least one ion exchange compartment between the anode compartment and the cathode compartment. The process comprises feeding an aqueous solution of an alkali metal chlorate to the ion exchange compartment, electrolyzing an anolyte in the anode compartment to generate hydrogen ions, passing the hydrogen ions from the anode compartment through a cation exchange membrane into the ion exchange compartment to displace alkali metal ions and produce an aqueous solution of chloric acid and alkali metal chlorate, passing alkali metal ions from the ion exchange compartment into the cathode compartment, removing the aqueous solution of chloric acid and alkali metal chlorate from the ion exchange compartment, and, increasing the concentration of chloric acid in the aqueous solution of chloric acid which is substantially free of anionic and cationic impurities to to provide a chloric acid concentration of 1.0 normal or greater.

Chloric acid-alkali metal chlorate mixtures for chlorine dioxide

A process for producing chlorine dioxide from an aqueous solution of chloric acid and alkali metal chlorate which is prouced in a electrolytic cell having an anode compartment, a cathode compartment and at least one ion exchange compartment between the anode and cathode compartments. The process includes the steps of feeding an aqueous solution of an alkali metal chlorate to the ion exchange compartment, electrolyzing an anolyte in the anode compartment to generate hydrogen ions, passing the hydrogen ions from the anode compartment through a cation exchange membrane into the ion exchange compartment to displace alkali metal ions and produce an aqueous solution of chloric acid and alkalimetal chlorate, passing the alkali metal ions from the ion exchange compartment into the cathode compartment, and finally passing the aqueous solution of chloric acid and alkali metal chlorate to a chlorate dioxide generator.

Electrochemical process for producing chloric acid-alkali metal chlorate

A particular side frame design for use in an electromechanical cell with a catholyte flow pattern is disclosed wherein the cell is angled from the horizontal and the catholyte is fed into a gap in the cathode compartment between the liquid metal cathode and the membrane on the lower first end and exits the gap on the opposing higher second outlet end. The side frame is obliquely angled on the interior of the cell to prevent the escape of the flowable liquid metal cathode and to prevent contact of the acidic catholyte with the cell bottom.

Liquid metal cathode electrochemical cell

A particular side frame design for use in an electrochemical cell with a catholyte flow pattern is disclosed wherein the cell can be generally horizontal or angled slightly from the horizontal and the catholyte is fed through a transition area into a gap in the catholyte compartment between the liquid metal cathode and the membrane on a first end and exits the gap on an opposing second outlet end. The side frame has opposing sides that are obliquely and downwardly angled in the corners to support the membrane in a wrinkle free manner so that the membrane is obliquely positioned between the liquid metal cathode and the anode. The membrane is above the level of the catholyte where the catholyte enters and exits the catholyte compartment, but drops to a level below the entry and exit points.

Liquid metal cathode electrochemical cell and cathode frame

A process for electrochemically treating an aqueous solution containing inorganic oxyhalide species is disclosed in which the aqueous solution is fed into the catholyte compartment of an electrochemical reduction cell using a high surface area cathode separated from an anolyte compartment to electrochemically reduce substantially all of the oxyhalide species to halide ions and produce a purified water product.

Process and apparatus for the removal of oxyhalide species from aqueous

An electrolytic filter press membrane cell and a method of operating the cell to produce concentrated perchloric acid are disclosed. The cell employs concentrated hypochlorous acid as the anolyte and operates with a two-stage single oxidation process at high current density.

Process for the production of perchloric acid

A process for producing chloric acid in an electrolytic cell having an anode and a cathode which includes feeding an aqueous solution of hypochlorous acid to the electrolytic cell, and electrolyzing the aqueous solution of hypochlorous solution to produce a chloric acid solution. Using the process of the invention, chloric acid can be produced efficiently at substantially reduced production costs using a process which can be operated commercially. In addition, the chloric acid solutions produced are of high purity and are stable at ambient conditions.

Electrochemical process for production of chloric acid from hypochlorous

A process for producing chlorine dioxide by oxidizing a hypochlorous acid solution to produce a chloric acid solution, and, electrolyzing the chloric acid solution to produce chlorine dioxide. The novel process of the present invention provides a commercially viable process for producing the chloric acid and eliminates the formation of an acidic salt solution in the production of chlorine dioxide which requires disposal. Further, the process permits a reduction in the amount of acid required in the generation of chlorine dioxide.

Growing community of inventors

Cleveland, TN, United States of America

Kenneth E Woodard, Jr