US3976549A — Electrolysis method

Claim 1

Independent Claim 98 words

A process for the electrolytic decomposition of aqueous solutions of ionizable chemical compounds which comprises electrolyzing an aqueous solution of an ionizable chemical compound in an electrolytic cell having an anode compartment and a cathode compartment separated by a unitary barrier having at least two layers of a permselective membrane material which is impervious to liquids and gases and is a copolymer of tetrafluoroethylene and a sulfonated perfluorovinyl ether of the formula FSO 2 CF 2 CF 2 OCF (CF 3 ) CF 2 OCF=CF 2 said copolymer having an equivalent weight of from about 900 to 1600.

Claim 2

Dependent Claim 98 words

A process for the electrolytic decomposition of aqueous solutions of ionizable chemical compounds which comprises electrolyzing an aqueous solution of an ionizable chemical compound in an electrolytic cell having an anode compartment and a cathode compartment separated by a unitary barrier having at least two layers of a permselective membrane material which is impervious to liquids and gases and is a copolymer of tetrafluoroethylene and a sulfonated perfluorovinyl ether of the formula FSO 2 CF 2 CF 2 OCF (CF 3 ) CF 2 OCF=CF 2 said copolymer having an equivalent weight of from about 900 to 1600.

Claim 3

Dependent Claim 13 words

The process of claim 1 wherein said anode compartment contains a metallic anode.

Claim 4

Dependent Claim 27 words

The process of claim 2 wherein said metallic anode consists essentially of a valve metal having thereon a coating comprising a noble metal or an oxide thereof.

Claim 5

Dependent Claim 11 words

The process of claim 3 wherein said valve metal is titanium.

Claim 6

Dependent Claim 19 words

The process of claim 4 wherein said titanium is coated with a mixture of ruthenium oxide and titanium oxide.

Claim 7

Dependent Claim 26 words

The process of claim 1 wherein said barrier consists essentially of a sandwich of at least two layers of said co-polymer separated by a porous membrane.

Claim 8

Dependent Claim 14 words

The process of claim 6 wherein said porous membrane is composed of asbestos sheet.

Claim 9

Dependent Claim 26 words

The process of claim 7 wherein said barrier consists of a sandwich of two layers of said co-polymer separated by a porous membrane of asbestos sheet.

Claim 10

Dependent Claim 21 words

A process as claimed in claim 1 wherein the said copolymer has an equivalent weight of from about 1100 to 1400.

Claim 11

Dependent Claim 16 words

The process of claim 1 wherein said barrier consists of two layers of said membrane material.

Claim 12

Dependent Claim 82 words

A process for the production of chlorine and caustic containing low concentration of sodium chloride which comprises electrolyzing aqueous brine solutions in a cell equipped with an anode and a cathode separated by a unitary permselective barrier having at least two layers of a hydrolyzed copolymer of tetrafluoroethylene and a sulfonated perfluorovinyl ether of the formula FSO 2 CF 2 CF 2 OCF (CF 3 ) CF 2 OCF=CF 2 said copolymer having an equivalent weight of from about 900 to 1600.

Claim 13

Dependent Claim 82 words

A process for the production of chlorine and caustic containing low concentration of sodium chloride which comprises electrolyzing aqueous brine solutions in a cell equipped with an anode and a cathode separated by a unitary permselective barrier having at least two layers of a hydrolyzed copolymer of tetrafluoroethylene and a sulfonated perfluorovinyl ether of the formula FSO 2 CF 2 CF 2 OCF (CF 3 ) CF 2 OCF=CF 2 said copolymer having an equivalent weight of from about 900 to 1600.

Claim 14

Dependent Claim 20 words

A process as claimed in claim 11 wherein said copolymer has an equivalent weight of from about 1100 to 1400.

Claim 15

Dependent Claim 37 words

A process as claimed in claim 12 wherein said hydrolyzed copolymer is obtained by treating a copolymer containing sulfonyl fluoride groups with a member of the group selected from boiling water and hot dilute aqueous caustic alkali.

Claim 16

Dependent Claim 29 words

A process as claimed in claim 13 wherein the copolymer containing sulfonyl fluoride groups is treated with boiling water to hydrolyze the sulfonyl fluoride groups to sodium sulfonate groups.

Claim 17

Independent Claim 148 words

A method of electrolytically decomposing ionizable chemical compounds which comprises introducing an aqueous solution of said ionizable chemical compound into an electrolytic cell having an anode compartment and a cathode compartment, said compartments being separated by a unitary barrier having at least two layers of a homogeneous cation active membrane formed from hydrolyzed copolymer of tetrafluoroethylene and a sulfonated perfluorovinyl ether of the formula FSO 2 CF 2 CF 2 OCF (CF 3 ) CF 2 OCF=CF 2 said copolymer having an equivalent weight of from about 900 to 1600, impressing a decomposition voltage of from about 2.3 volts to 5 volts across the electrodes disposed in each of said compartments while maintaining an anode current density of from about 0.5 to 4 amperes per square inch and recovering from said cathode compartment a product containing less than about one percent by weight of said ionizable chemical compound.

Claim 18

Independent Claim 148 words

A method of electrolytically decomposing ionizable chemical compounds which comprises introducing an aqueous solution of said ionizable chemical compound into an electrolytic cell having an anode compartment and a cathode compartment, said compartments being separated by a unitary barrier having at least two layers of a homogeneous cation active membrane formed from hydrolyzed copolymer of tetrafluoroethylene and a sulfonated perfluorovinyl ether of the formula FSO 2 CF 2 CF 2 OCF (CF 3 ) CF 2 OCF=CF 2 said copolymer having an equivalent weight of from about 900 to 1600, impressing a decomposition voltage of from about 2.3 volts to 5 volts across the electrodes disposed in each of said compartments while maintaining an anode current density of from about 0.5 to 4 amperes per square inch and recovering from said cathode compartment a product containing less than about one percent by weight of said ionizable chemical compound.

Claim 19

Dependent Claim 39 words

The method as described in claim 15 wherein said ionizable chemical compound is an alkali metal chloride and the product recovered from said cathode compartment is an alkali metal hydroxide containing less than one percent of alkali metal chloride.

Claim 20

Dependent Claim 15 words

The method as described in claim 16 wherein the alkali metal chloride is sodium chloride.

Claim 21

Dependent Claim 39 words

The method as described in claim 17 wherein the sodium chloride solution contains from about 200 gpl to 320 gpl sodium chloride and the sodium hydroxide concentration in the cathode compartment is maintained above about 10 percent by weight.

Claim 22

Dependent Claim 28 words

The method as described in claim 11 wherein the sodium hydroxide concentration in the cathode compartment is maintained from about 24 percent to about 38 percent by weight.

Claim 23

Dependent Claim 22 words

The method as described in claim 17 wherein the sodium chloride solution has a pH of from about 1 to about 5.

Claim 24

Dependent Claim 21 words

The method as described in claim 20 wherein the sodium chloride solution has a pH of from about 3.0 to 4.5.

Claim 25

Dependent Claim 17 words

The process of claim 15 wherein said barrier consists of two layers of said cation active membrane.

Claim 26

Dependent Claim 104 words

A process for the electrolytic decomposition of aqueous solutions of ionizable chemical compounds which comprises electrolyzing an aqueous solution of an ionizable chemical compound in an electrolytic cell having at least one bipolar electrode, an anode compartment and a cathode compartment, said compartments being separated by a unitary barrier having two layers of a permselective membrane material which is impervious to liquids and gases and is a copolymer of tetrafluoroethylene and a sulfonated perfluorovinyl ether of the formula FSO 2 CF 2 CF 2 OCF (CF 3 ) CF 2 OCF=CF 2 said copolymer having an equivalent weight of from about 900 to 1600.

Claim 27

Dependent Claim 104 words

A process for the electrolytic decomposition of aqueous solutions of ionizable chemical compounds which comprises electrolyzing an aqueous solution of an ionizable chemical compound in an electrolytic cell having at least one bipolar electrode, an anode compartment and a cathode compartment, said compartments being separated by a unitary barrier having two layers of a permselective membrane material which is impervious to liquids and gases and is a copolymer of tetrafluoroethylene and a sulfonated perfluorovinyl ether of the formula FSO 2 CF 2 CF 2 OCF (CF 3 ) CF 2 OCF=CF 2 said copolymer having an equivalent weight of from about 900 to 1600.

Claim 28

Dependent Claim 43 words

The process of claim 23 wherein the cathode side of said bipolar electrode is formed of steel and the anode side of said bipolar electrode is formed of a valve metal having a coating thereon comprising a noble metal or noble metal oxide.

Claim 29

Dependent Claim 18 words

The process of claim 24 wherein said valve metal is titanium and the coating thereon comprises ruthenium oxide.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1979-08-24	1980-02-23	1980-08-24	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1983-08-24	1984-02-23	1984-08-24	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1987-08-24	1988-02-23	1988-08-24	$7700.00	Window Closed / Lapsed

Electrolysis method

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