Abstract: The invention concerns a process and an apparatus for continuously producing chlorine dioxide, the process comprising the steps of

Abstract: The invention relates to a novel composition useful as a feed at production of chlorine dioxide, said composition being an aqueous solution comprising from about 1 to about 6.5 moles/liter of alkali metal chlorate, from about 1 to about 7 moles/liter of hydrogen peroxide and at least one of a protective colloid, a radical scavenger or a phosphonic acid based complexing agent, wherein the pH of the aqueous solution is from about 1 to about 4.

Abstract: A method for producing chlorine dioxide by activating zeolite crystals (which have been impregnated with metal chlorite such as sodium chlorite, and optionally also a water-retaining substance such as magnesium sulfate, potassium chloride, potassium hydroxide, or calcium chloride) with excess protons, or activating an aqueous solution of metal chlorite and such a water-retaining substance with excess protons. Proton generating species useful for the activation are acids such as acetic, phosphoric, and citric acid, and metal salts such as ferric chloride, ferric sulfate, ZnSO4, ZnCl2, CoSO4, CoCl2, MnSO4, MnCl2, CuSO4, CuCl2, and MgSO4. The activation can be performed by causing fluid to flow through a bed of zeolite crystals impregnated with calcium chloride (or other water-retaining substance) and sodium chlorite, and a bed of zeolite crystals impregnated with a proton generating species. The two beds can be physically mixed together or the fluid can flow sequentially through separate beds.

Abstract: The invention relates to a novel composition useful as a feed at production of chlorine dioxide, said composition being an aqueous solution comprising from about 1 to about 6.5 moles/liter of alkali metal chlorate, from about 1 to about 7 moles/liter of hydrogen peroxide and at least one of a protective colloid, a radical scavenger or a phosphonic acid based complexing agent, wherein the pH of the aqueous solution is from about 1 to about 4.

Abstract: Method and system for generating chlorine dioxide gas in a controlled release manner by combining at least one metal chlorite and a solid material that reacts with the metal chlorite in the presence of water vapor, but does not react with the metal chlorite in the substantial absence of liquid water or water vapor to produce chlorine dioxide gas in a sustained amount of from about 0.025 to 1,000 ppm.

Abstract: A novel method is described whereby chlorine dioxide is produced through the chemical reduction of ammonium chlorate in an aqueous acidic solution. The reduction reaction takes place at elevated temperatures with or without a catalyst. The reducing agent of this reaction is preferably hydrogen peroxide, glycerol, or sucrose. Chlorine dioxide may be produced in accordance with this invention at a substantially higher rate and in higher yield than with conventional methods using sodium chlorate. Further, the chlorine dioxide produced is substantially chloride-free. The ammonium sulfate by-product of this method has direct use as a fertilizer.

Abstract: Alkali metal chlorite, particularly sodium chlorite, is produced with a low carbonate level by combining a chlorine dioxide generating system operating at subatmospheric pressure with a chlorite formation reactor in which the chlorine dioxide reacts with hydrogen peroxide in the presence of aqueous alkali metal hydroxide, particularly sodium hydroxide.

Abstract: Chlorine dioxide is generated by electrochemical oxidation of sodium chlorite in an anode compartment of a cation-exchange membrane-divided cell in the presence of significant quantities of sodium chlorate and is recovered in a suitable recipient medium by passing the chlorine dioxide through a hydrophobic microporous membrane. Water balance in a continuous operation is maintained by removing water from the anolyte by transporting the same partly across the hydrophobic microporous membrane in vapor form and partly across the cation-exchange membrane.

Abstract: Chlorine dioxide is generated by electrochemical oxidation of sodium chlorite in an anode compartment of a cation-exchange membrane-divided cell and is recovered in a suitable recipient medium by passing the chlorine dioxide through a hydrophobic microporous membrane. Water balance in a continuous operation is maintained by removing water from the anolyte by transporting the same partly across the hydrophobic microporous membrane in vapor form and partly across the cation-exchange membrane.

Abstract: The invention relates to a process of producing chlorine dioxide by the reduction of chlorate ions with hydrogen peroxide as a reducing agent in a tubular reactor, preferably in the presence of a mineral acid, wherein the preferable degree of chlorate conversion in the reactor is above about 75%, preferably from about 80 to 100%.

Abstract: The invention relates to a process of producing chlorine dioxide comprising the steps: Providing a reactor with an aqueous acidic reaction medium containing alkali metal chlorate and sulfate; reducing chlorate ions in said reaction medium to form chlorine dioxide; maintaining the reaction medium at subatmospheric pressure sufficient to evaporate water and precipitate alkali metal sulfate; withdrawing chlorine dioxide and evaporated water from the reactor; withdrawing reaction medium containing solid alkali metal sulfate from the reactor and separating the solid material from said reaction medium; transferring reaction medium substantially free from solid alkali metal sulfate to an electrochemical cell in which the acidity of said reaction medium is increased and the content of alkali metal ions is decreased; recycling electrochemically acidified reaction medium to the reactor for producing chlorine dioxide; and adding make up alkali metal chlorate and sulfuric acid.

Abstract: A method for producing chlorine dioxide by activating a mixture of impregnated zeolite crystals, the mixture itself, and a method for regenerating the mixture after chlorine dioxide production. The activation is accomplished by causing water or a moisture-containing gas (e.g., air including water vapor) to flow through the mixture or otherwise exposing the mixture to such fluid, or by exposing the mixture to liquid hydrogen peroxide, liquid sulfuric acid, ferric chloride solution, or sodium chlorate solution. The mixture can include sodium chlorite-impregnated zeolite crystals and zeolite crystals impregnated with ferric chloride, ferric sulfate, or both, and optionally also zeolite crystals impregnated with calcium chloride.

Abstract: Chlorine dioxide is produced by reaction of chlorate ions, usually provided by sodium chlorate, with a persulfate in an aqueous acid reaction medium containing sulfuric acid. By-product sodium sulfate, sulfuric acid feedstock or mixture may be electrolyzed to form the persulfate for the reaction.

Abstract: A process for production of chlorine dioxide which is substantially free of by product chlorine. Chlorine-dioxide is produced from an alkali metal chlorate, a mineral acid and a reducing agent such as methanol in a reaction medium maintained at an acid normality of less than 9 and with a high chlorate molarity. The process is carried out in the substantial absence of additional chloride ion being fed to the process. It has been found that increasing the chlorate concentration at a given acid normality reduces the amount of chloride in the reaction medium thus reducing the amount of chlorine by-product. The process is carried out in a vessel operated under subatmospheric pressure, whereby water is evaporated and withdrawn together with chlorine dioxide and the alkali metal salt of the mineral acid is crystallized within the reaction vessel and withdrawn therefrom.

Abstract: A method of preparing chlorine dioxide in a non-aqueous liquid is disclosed. An aqueous solution of chlorine dioxide is mixed and agitated with a non-aqueous liquid. The chlorine dioxide is extracted into the non-aqueous liquid. In a preferred embodiment, an aqueous chlorite solution is added to a quantity of non-aqueous liquid. Acid is added to the aqueous phase to generate chlorine dioxide. The phases are vigorously agitated to extract the chlorine dioxide into the non-aqueous phase. High concentrations of very pure chlorine dioxide are obtainable. In another preferred embodiment, chlorine is prepared in a non-aqueous liquid and is mixed and agitated with an aqueous chlorite solution. Separation of the aqueous and non-aqueous phases provides pure solutions of chlorine dioxide in the non-aqueous liquid. Very pure aqueous solutions of chlorine dioxide are prepared by mixing and agitating non-aqueous solutions of chlorine dioxide with water.

Abstract: Chlorine dioxide is produced by reaction of sodium chlorate, a reducing agent, preferably methanol or hydrogen peroxide, and sulfuric acid at the boiling point of the reaction medium under a subatmospheric pressure. Present in the reaction medium is a component which suppresses the solubility of by-product sodium sulfate and thereby increases the concentration of free hydrogen ions in the reaction medium available for reaction to form chlorine dioxide. The solubility-depressing component generally is an inert alkali metal salt, preferably an inert sodium salt, such as perchlorate or nitrate. By increasing the concentration of hydrogen ions available for reaction, it is possible to achieve an improvement in the rate of production of chlorine dioxide.

Abstract: The invention relates to a process of producing chlorine dioxide comprising the steps of reducing chlorate ions in an acid reaction medium maintained in a reaction zone of a chlorine dioxide generator, which reaction medium contains alkali metal ions and sulfate ions, so to form chlorine dioxide and a solid salt of acidic alkali metal sulfate.

Abstract: 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.

Abstract: Sodium sesquisulfate produced in crystalline form in a high acidity highly efficient chlorine dioxide generating process is converted by metathesis to crystalline anhydrous neutral sodium sulfate and the acid recovered as a result is recycled to the chlorine dioxide generating step. The metathesis is effected by contacting the crystalline sodium sesquisulfate with aqueous sodium chlorate solution, aqueous sodium chloride solution, aqueous methanol or water alone. The metathesis is effected in such manner as to minimize the additional evaporative load imposed on the chlorine dioxide generating process by the metathesis medium.

Abstract: The invention relates to a process of producing chlorine dioxide using, in a first alternative atmospheric pressure and hydrogen peroxide in the reaction medium optionally with an electrolytic cell. In a second alternative, either atmospheric or subatmospheric pressure is used in the reaction medium together with an organic or inorganic reducing agent and an electrolytic cell.

Abstract: A process for the production of chlorine dioxide by reacting at least one of chloric acid and an alkali metal chlorate, and hydrogen peroxide as the reducing agent in such proportions that chlorine dioxide is produced in a reaction medium. A mixture comprising chlorine dioxide and oxygen is withdrawn from the reaction medium. Urea and/or one or more phosphonic acid based complexing agents are added to the reaction medium. The stabilizer is added in an amount of 0.01-5 weight % and serves to increase the reaction rate.

Abstract: Disclosed is a process of producing chlorine dioxide having the steps of providing a reactor with an aqueous acidic reaction medium containing alkali metal chlorate and phosphate; reducing chlorate ions in the reaction medium to form chlorine dioxide; withdrawing chlorine dioxide gas from the reaction medium; withdrawing reaction medium from the reactor and transferring it to an electrochemical cell; treating the reaction medium electrochemically to increase the acidity and decrease the content of alkali metal ions; recycling the acidified reaction medium to the reactor; and adding make up alkali metal chlorate to the reaction medium before or after the electrochemical cell.

Abstract: The invention relates to a process of producing chlorine dioxide using, in a first alternative atmospheric pressure and hydrogen peroxide in the reaction medium optionally with an electrolytic cell. In a second alternative, either atmospheric or subatmospheric pressure is used in the reaction medium together with an organic or inorganic reducing agent and an electrolytic cell.

Abstract: The invention relates to a method of producing chlorine dioxide, which method comprises reacting chloric acid with hydrogen peroxide as a reducing agent in such proportions that chlorine dioxide is produced.

Abstract: Liquid effluent from a pulp mill bleach plant having at least one chlorine chemical bleach stage is evaporated and then used in chlorate manufacture. The bleach plant effluent produced by evaporation may be stored and then transported to an off-site chlorate production location, and/or may be subjected to a sodium chloride removal process (such as evaporative crystallization) and only sodium chloride transported to the off-site location. Chlorates produced off site can be returned to the mill (with acid and caustic that are optionally produced) for chlorine dioxide manufacture on site. The chloride-depleted stream from sodium chloride removal may be burned in the mill recovery boiler.

Abstract: An improvement is provided in a process for the preferential removal of chlorine from an aqueous solution of chlorine dioxide and chlorine which has been prepared by the process of reducing a chlorate with a reducing agent in a strong acid, and wherein the gases produced thereby are dissolved in water. The improvement comprises the step of adding hydrogen peroxide, oxalic acid or a salt of oxalic acid, to a cool (i.e. at a temperature of about 0.degree. C. to about 25.degree. C.) aqueous solution of the chlorine within a period of less than 2.5 hours dioxide and chlorine. Substantially all of the chlorine is destroyed with almost no destruction of the chlorine dioxide.

Abstract: A method for generating chlorine dioxide by reduction of sodium chlorate includes electrolyzing sodium sulfate by-product to form acid. The acid is then used to acidify the chlorine dioxide generating solution.

Abstract: The invention relates to a process for electrolytic production of alkali metal chlorate where the demand of pH-adjusting chemicals is largely covered by integrated production of acid and alkali metal hydroxide. The process consists in electrolyzing a partial flow of chlorate electrolyte produced, in a cell provided with a separator, for producing a catholyte containing alkali metal hydroxide and an anolyte containing hydrochloric acid. The catholyte and the anolyte are used in alkalization and acidification in the chlorate process, thus significantly reducing the admission of impurities via externally produced chemicals.

Abstract: A method of preparing chlorine dioxide in a non-aqueous liquid is disclosed. An aqueous solution of chlorine dioxide is mixed and agitated with a non-aqueous liquid. The chlorine dioxide is extracted into the non-aqueous liquid. In a preferred embodiment, an aqueous chlorite solution is added to a quantity of non-aqueous liquid. Acid is added to the aqueous phase to generate chlorine dioxide. The phases are vigorously agitated to extract the chlorine dioxide into the non-aqueous phase. High concentrations of very pure chlorine dioxide are obtainable. In another preferred embodiment, chlorine is prepared in a non-aqueous liquid and is mixed and agitated with an aqueous chlorite solution. Separation of the aqueous and non-aqueous phases provides pure solutions of chlorine dioxide in the non-aqueous liquid. Very pure aqueous solutions of chlorine dioxide are prepared by mixing and agitating non-aqueous solutions of chlorine dioxide with water.

Abstract: Solid sodium sesquisulfate is metathesized by water to neutral anhydrous sodium sulfate and to recover the acid values therefrom by employing a dynamic leaching of the solid phase sodium sesquisulfate, to provide an acid medium for recycle to a chlorine dioxide generating process producing the sodium sesquisulfate without significantly increasing the evaporative load on the generator.

Abstract: A process for continuously producing chlorine dioxide by reacting an alkali metal chlorate, sulfuric acid or another chlorine free mineral acid and hydrogen peroxide as reducing agent to produce chlorine dioxide in an aqueous reaction medium. In the process chlorine dioxide is generated in at least one reaction step comprising at least one reaction vessel, by feeding alkali metal chlorate, acid, hydrogen peroxide and inert gas to said reaction vessel, in substantial absence of added chloride ions. The aqueous reaction medium in said reaction vessel is maintained at a pressure of from about 400 mm Hg to about 900 mm Hg and at a temperature of from about 35.degree. C. to about 100.degree. C. and at an acidity within a range from about 4 to about 14 N and the chlorate concentration of between about 0.05 moles/1 to saturation. Chlorine dioxide, oxygen and inert gas and the depleted aqueous reaction medium is withdrawn from said reaction zone without substantial crystallization of alkali metal sulfate.

Abstract: A process is disclosed for producing a dilute solution of an alkali or alkaline earth metal chlorate from a chlorine and carbon dioxide waste gaseous stream. The process of the invention can be combined in a continuous process for the production of an alkali or alkaline earth metal chlorate for use in a chlorine dioxide generator for the production of chlorine dioxide in which the waste gaseous stream from the chlorine dioxide generator is converted to a dilute solution of an alkali or alkaline earth metal chlorate and passed to an electrochemical cell for the generation of an alkali or alkaline earth metal sodium chlorate, the product of the electrochemical cell being in turn passed to the chlorine dioxide generator.

Abstract: A plug flow process for the production of chlorine dioxide by reacting chloric acid and/or an alkali metal chlorate, optionally a mineral acid and a reducing agent in such proportions that chlorine dioxide is produced. Reactants are continuously fed to a plug flow reactor under conditions that chloride dioxide is produced as the reactants flow through the reactor. The process stream has an acidity between 2N and 11N. The process stream is subjected to superatmospheric pressure in the reactor sufficient to maintain the formed chlorine dioxide in solution. After removal of the chlorine dioxide from the process stream exiting the plug flow reactor, the process stream can optionally be fed to a second chlorine dioxide generator for further reaction.

Abstract: Chlorine dioxide is continuously produced at high efficiency in a single vessel process by reduction of chlorate ions with hydrogen peroxide in an aqueous acidic medium. The hydrogen peroxide is pre-mixed with at least a portion of the aqueous chlorate solution feed or the sulfuric acid feed or a mixture thereof. By pre-mixing the hydrogen peroxide feed, the occasional decomposition of hydrogen peroxide and the resulting foaming of the generator liquor is eliminated.

Abstract: 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.

Abstract: A process which comprises heating a reaction mixture comprised of an aqueous solution containing perchlorate ions, chlorate ions and hydrogen ions to produce chlorine dioxide and oxygen gas.The novel process of the present invention provides a commercially viable process for producing chlorine dioxide from mixtures of oxy-chlorine species in the absence of a reducing agent. The process can be operated without producing an acidic salt by-product while producing a chlorine dioxide product which is substantially free of chlorine. In addition, the process of the invention permits a reduction in the amount of acid fed to the chlorine dioxide generator.

Abstract: A novel continuous process and system are provided for the production of chlorine dioxide at favorable economics and high efficiency. The process involves effecting electrolysis of an aqueous solution of alkali metal chloride, in an electrolysis zone, to form an aqueous solution of alkali metal chlorate having a chlorate ion concentration of about 400 to about 1,200 g/L, and a chloride ion concentration of about 90 to about 120 g/L, gaseous hydrogen and water vapor. Hydrogen is conducted to a hydrogen chloride synthesis system where it reacts with chlorine gas, (recycled, as well as make-up,) to yield hydrogen chloride gas which is quenched with water to provide hydrochloric acid. A solution of alkali metal chlorate is conducted from the electrolysis zone to the chlorine dioxide generating zone.

Abstract: A process for producing chlorine dioxide a solution of chloric acid is reduced in the presence of an externally added load of perchlorate ions to form chlorine dioxide.

Abstract: Chloride dioxide for a cellulose pulp mill bleach plant is produced by concentrating (evaporating) liquid effluents from the bleach plant to a concentration level high enough for incineration, incinerating the concentrated effluents to produce an ash, chemically reacting at least a part of the ash to produce chlorate, and using the chlorate in the manufacture of chlorine dioxide. The ash is purified to produce sodium chloride and the sodium chloride is reacted with oxygen and external energy to produce sodium chlorate. The chlorate is then used in the manufacture of chlorine dioxide. Sulfates produced are used to manufacture acid and/or caustic, and heavy metal hydroxides are disposed of. A part of the ash may be used directly in chlorine dioxide manufacture. At least some of the salt from chlorate manufacture may be fed to the chemical recovery loop, including a recovery boiler, in the pulp mill. Evaporated gases may be returned to the pulp mill and bleach plant.

Abstract: 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.

Abstract: An integrated process for the production of alkali or alkaline earth metal chlorates and chlorine dioxide in which the chromium compound impurities in the alkali or alkaline earth metal chlorate aqueous solution produced by an electrochemical cell are removed and recycled to the electrochemical cell; a substantially chromium compound free alkali or alkaline earth metal chlorate is converted to chlorine dioxide and by-products; and the by-products are converted to substantially chlorine-free carbon dioxide, which is vented, and a dilute solution of an alkali or alkaline earth metal chlorate, which is recycled to the electrochemical cell.

Abstract: Chlorine dioxide, useful as a pulp mill chemical, is produced without producing sodium sulfate effluent for disposal, by effecting reduction of chloric acid in an aqueous reaction medium in a reaction zone at a total acid normality of up to about 7 normal in the substantial absence of sulfate ion and in the promence of a dead load of sodium chlorate added to and subsequently removed from the reaction medium. Chloric acid for the process is produced electrolytically from an aqueous solution of the deadload sodium chlorate and make-up quantities of sodium chlorate. The chloric acid reduction to produce chlorine dioxide may be effected using methanol or electrolytically.

Abstract: A process for the production of chlorine dioxide by reacting at least one of chloric acid and an alkali metal chlorate, and hydrogen peroxide as the reducing agent in such proportions that chlorine dioxide is produced in a reaction medium. A mixture comprising chlorine dioxide and oxygen is withdrawn from the reaction medium. Urea and/or one or more phosphonic acid based complexing agents are added to the reaction medium. The stabilizer is added in an amount of 0.01-5 weight % and serves to increase the reaction rate.

Abstract: A process for producing chlorine dioxide is provided which reacts an aqueous solution of chloric acid and an alkali metal chlorate with a solution of a non-oxidizable acid in the presence of an oxygen-evolving catalyst in a reaction zone to produce a gaseous mixture of chlorine dioxide gas, oxygen, water vapor and an aqueous solution of the non-oxidizable acid and an alkali metal salt of the non-oxidizable acid. The gaseous mixture of chlorine dioxide gas and oxygen are separated from the aqueous solution of the non-oxidizable acid and alkali metal salt of the non-oxidizable acid, while the aqueous solution of the non-oxidizable acid and alkali metal salt of the non-oxidizable acid is fed to the anode compartment of three compartment electrolytic cell having at least one ion exchange compartment between an anode and a cathode compartment.

Abstract: 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, in a process which comprises:a) feeding an aqueous solution of an alkali metal chlorate to the ion exchange compartment,b) passing hydrogen and alkali metal ions from the anode compartment through a cation exchange membrane into the ion exchange compartment, wherein the hydrogen ions displace alkali metal ions to produce an aqueous solution of chloric acid and alkali metal chlorate,c) passing alkali metal ions from the ion exchange compartment into the cathode compartment,d) electrolyzing the aqueous solution of chloric acid and alkali metal chlorate in the anode compartment to produce an aqueous solution of chloric acid, alkali metal chlorate, hydrogen ions and perchlorate ions as a minor constituent.

Abstract: 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.

Abstract: Sodium sesquisulfate produced in crystalline form in a high acidity methanol-based highly efficient chlorine dioxide generating process is converted by metathesis to crystalline anhydrous neutral sodium sulfate and the acid recovered as a result is recycled to the chlorine dioxide generating step. The metathesis is effected by contacting the crystalline sodium sesquisulfate with aqueous sodium chlorate solution, aqueous sodium chloride solution, aqueous methanol or water alone. The metathesis is effected in such manner as to minimize the additional evaporative load imposed on the chlorine dioxide generating process by the metathesis medium.

Abstract: A process for the rapid generation of chlorine dioxide under reduced pressure. A reaction column having a venturi therein and a reaction chamber in fluid communication with the nozzle of the venturi is provided. An aqueous chlorate solution and a gaseous stream of acid are introduced into the reaction chamber to react and form chlorine dioxide. A driving medium is introduced into the venturi, and the chlorine dioxide from the reaction chamber is mixed with the driving medium at the outlet of the venturi. The chlorine dioxide/driving medium mixture is passed through a reaction column. In an alternate embodiment, a chlorite solution is introduced into the reaction chamber together with the chlorate solution and the gaseous stream of acid. In a further embodiment, a chlorite solution is introduced into the reaction column after mixing of the driving medium with the chlorine dioxide.

Abstract: Chlorine dioxide, useful as a pulp mill chemical, is produced without producing sodium sulfate effluent for disposal, by effecting reduction of chloric acid in an aqueous reaction medium in a reaction zone at a total acid normality of up to about 7 normal in the substantial absence of sulfate ion and in the presence of a dead load of sodium chlorate added to and subsequently removed from the reaction medium. Chloric acid for the process is produced electrolytically from an aqueous solution of the deadload sodium chlorate and make-up quantities of sodium chlorate. The chloric acid reduction to produce chlorine dioxide may be effected using methanol or electrolytically.

Abstract: A process which comprises heating a reaction mixture comprised of an aqueous solution containing perchlorate ions, chlorate ions and hydrogen ions to produce chlorine dioxide and oxygen gas.The novel process of the present invention provides a commercially viable process for producing chlorine dioxide from mixtures of oxy-chlorine species in the absence of a reducing agent. The process can be operated without producing an acidic salt by-product while producing a chlorine dioxide product which is substantially free of chlorine. In addition, the process of the invention permits a reduction in the amount of acid fed to the chlorine dioxide generator.