Production of chlorine dioxide

Claim 3

The method of claim 1 including forming an aqueous solution of said chlorine dioxide present in said removed gaseous admixture.

Claim 4

The method of claim 1 carried out continuously and wherein said alkali metal is sodium.

Claim 5

The method of claim 3 including separating the chlorine present in said removed gaseous admixture substantially completely therefrom, forming an aqueous solution of said chlorine dioxide in said removed gaseous admixture, and utilizing said separated chlorine as at least part of said chlorine reacting with the hydrogen in said first stream to form hydrogen chloride.

Claim 6

The method of claim 3 including removing said sodium chloride from said reaction zone, forming an aqueous solution thereof, and utilizing said aqueous solution thereof as the aqueous solution electrolyzed to form the sodium chlorate and hydrogen.

Claim 7

The method of claim 4 including removing said sodium chloride from said reaction zone, forming an aqueous solution thereof, and utilizing said aqueous solution thereof as the aqueous solution electrolyzed to form the sodium chlorate and hydrogen.

Claim 8

The method of claim 1 including reacting the hydrogen in said second stream with oxygen to form water.

Claim 9

A cyclic continuous method of forming chlorine dioxide which includes: electrolyzing an aqueous solution of an alkali metal chloride to form an alkali metal chlorate and hydrogen in accordance with the equation: MCl + 3H2O -> MClO3 + 3H2 where M is an alkali metal, providing said formed alkali metal chlorate as an aqueous solution thereof and continuously forwarding said aqueous solution to a reaction zone, continuously separating said hydrogen into a first stream containing slightly in excess of one-third of the mole quantity of said hydrogen and a second stream containing the remainder of the mole quantity of said hydrogen, continuously recovering said second stream of hydrogen, reacting the one-third mole quantity of hydrogen in said first stream thereof with chlorine to form hydrogen chloride in accordance with the equation: H2 + Cl2 -> 2HCl and provide said slightly excess quantity of hydrogen associated with said hydrogen chloride, continuously forwarding said hydrogen chloriDe and slightly excess quantity of hydrogen to said reaction zone to provide with said continuously forwarded aqueous solution of alkali metal chlorate an aqueous reaction medium in said reaction zone containing an alkali metal chlorate and hydrochloric acid, continuously maintaining the acidity of said reaction medium at about 0.05 to below about 1 normal, continuously controlling the feeds of said alkali metal chlorate and hydrogen chloride to said reaction zone to provide approximately 2 moles of hydrogen chloride for each mole quantity of alkali metal chlorate fed to said reaction zone, continuously maintaining said reaction medium at its boiling point at the absolute pressure of said reaction zone, said boiling point being at an elevated temperature below that above which substantial decomposition of chlorine dioxide occurs, continuously effecting reaction between said alkali metal chlorate and hydrochloric acid in said reaction medium at said elevated temperature while said reaction zone is maintained under a subatmospheric pressure continuously to form chlorine dioxide and chlorine predominantly in accordance with the equation: MClO3 + 2HCl -> ClO2 + 1/2 Cl2 + MCl + H2O where M is an alkali metal, continuously evaporating water from said reaction medium at said elevated temperature to maintain the liquid level in said reaction zone substantially constant and forming in said reaction zone a gaseous admixture consisting essentially of said formed chlorine dioxide and chlorine, evaporated water and said slightly excess quantity of hydrogen, continuously removing said gaseous admixture from said reaction zone, continuously depositing alkali metal chloride from said reaction medium in said reaction zone once the alkali metal chloride saturates the reaction medium at said elevated temperature upon initial commencement of the process, continuously recovering said chlorine dioxide in said removed gaseous admixture, and continuously separating said slightly excess quantity of hydrogen from said removed gaseous admixture substantially free from chlorine dioxide and chlorine.

Claim 10

A cyclic continuous method of forming chlorine dioxide which includes: electrolyzing an aqueous solution of an alkali metal chloride to form an alkali metal chlorate and hydrogen in accordance with the equation: MCl + 3H2O -> MClO3 + 3H2 where M is an alkali metal, providing said formed alkali metal chlorate as an aqueous solution thereof and continuously forwarding said aqueous solution to a reaction zone, continuously separating said hydrogen into a first stream containing slightly in excess of one-third of the mole quantity of said hydrogen and a second stream containing the remainder of the mole quantity of said hydrogen, continuously recovering said second stream of hydrogen, reacting the one-third mole quantity of hydrogen in said first stream thereof with chlorine to form hydrogen chloride in accordance with the equation: H2 + Cl2 -> 2HCl and provide said slightly excess quantity of hydrogen associated with said hydrogen chloride, continuously forwarding said hydrogen chloriDe and slightly excess quantity of hydrogen to said reaction zone to provide with said continuously forwarded aqueous solution of alkali metal chlorate an aqueous reaction medium in said reaction zone containing an alkali metal chlorate and hydrochloric acid, continuously maintaining the acidity of said reaction medium at about 0.05 to below about 1 normal, continuously controlling the feeds of said alkali metal chlorate and hydrogen chloride to said reaction zone to provide approximately 2 moles of hydrogen chloride for each mole quantity of alkali metal chlorate fed to said reaction zone, continuously maintaining said reaction medium at its boiling point at the absolute pressure of said reaction zone, said boiling point being at an elevated temperature below that above which substantial decomposition of chlorine dioxide occurs, continuously effecting reaction between said alkali metal chlorate and hydrochloric acid in said reaction medium at said elevated temperature while said reaction zone is maintained under a subatmospheric pressure continuously to form chlorine dioxide and chlorine predominantly in accordance with the equation: MClO3 + 2HCl -> ClO2 + 1/2 Cl2 + MCl + H2O where M is an alkali metal, continuously evaporating water from said reaction medium at said elevated temperature to maintain the liquid level in said reaction zone substantially constant and forming in said reaction zone a gaseous admixture consisting essentially of said formed chlorine dioxide and chlorine, evaporated water and said slightly excess quantity of hydrogen, continuously removing said gaseous admixture from said reaction zone, continuously depositing alkali metal chloride from said reaction medium in said reaction zone once the alkali metal chloride saturates the reaction medium at said elevated temperature upon initial commencement of the process, continuously recovering said chlorine dioxide in said removed gaseous admixture, and continuously separating said slightly excess quantity of hydrogen from said removed gaseous admixture substantially free from chlorine dioxide and chlorine.

Claim 11

The process of claim 8 wherein said recovery of chlorine dioxide and separating of said slightly excess quantity of hydrogen are carried out by continuously contacting said gaseous admixture with an aqueous material to condense said evaporated water and to form an aqueous solution of the chlorine dioxide present in said gaseous admixture and a gaseous stream containing said slightly excess quantity of hydrogen and at least a substantial quantity of the chlorine content of said gaseous admixture and continuously separating said slightly excess quantity of hydrogen from said chlorine.

Claim 12

The process of claim 9 wherein said separating of said slightly excess quantity of hydrogen from said chlorine is carried out by continuously dividing said gaseous stream into two streams, mixing one of said latter streams containing a quantity of hydrogen equivalent to said slightly excess quantity of hydrogen with said second stream of hydrogen, continuously scrubbing the resulting combined stream to dissolve the chlorine therefrom and to provide a combined hydrogen stream containing said slightly excess quantity of hydrogen, continuously utilizing the resulting chlorine solution as part of the aqueous material used in contacting said gaseous admixture, utilizing the chlorine in the other of said latter streams and containing a recycled quantity of hydrogen as at least part of the chlorine reacting with the hydrogen of the first stream to provide the hydrogen chloride associated with an excess quantity of hydrogen including recycled hydrogen and said slightly excess quantity of hydrogen.

Claim 13

The process of claim 10 wherein said alkali metal is sodium and including removing said deposited sodium chloride from said reaction zone, forming an aqueous solution thereof, and utiliziNg the latter aqueous solution as said electrolyzed aqueous solution of alkali metal chloride.

Claim 14

The process of claim 10 including reacting the hydrogen in said combined hydrogen stream with oxygen to form water.