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US 4,391,680 AGranted
Preparing alkali metal hydroxide by water splitting and hydrolysis
AssigneeAllied Corporation
InventorsKrishnamurthy Mani, Frederick P. Chlanda
Life of this patent
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Abstract
A two-compartment water splitter having alternating cation and bipolar membranes is used to remove alkali metal cations from an aqueous alkali metal chloride solution so as to produce an acidified salt solution. The coproduct is a base such as NaOH or KOH. The acidified salt solution may then be fed to a membrane or diaphragm electrolytic cell for production of chlorine and alkali metal hydroxide.
Claims16
A process which comprises the steps:
- (a) introducing aqueous alkali metal chloride solution into each first compartment between a cation membrane and a cation side of a bipolar membrane of an electrodialytic water splitter comprised of alternating cation and bipolar membranes, said membranes being positioned between an anode and a cathode,
- (b) introducing into each second compartment between a cation membrane and an anion side of a bipolar membrane a liquid comprising water,
- (c) passing a direct current through said water splitter thereby causing acidification of said aqueous alkali metal chloride solution and basification of said liquid comprising water and transfer of alkali metal cations from said aqueous salt solution to said liquid comprising water,
- (d) withdrawing from said second compartments a liquid comprising aqueous alkali metal hydroxide,
- (e) withdrawing from said first compartments an acidified aqueous salt solution comprising between about 0.6 and 13 moles HCl per 100 hundred moles alkali metal chloride, and
- (f) feeding said acidified salt solution to the anode compartment of a diaphragm or membrane electrolytic cell.
3 more elements
A process of forming an acidified aqueous salt solution comprising the steps:
- (a) introducing aqueous alkali metal chloride solution into each first compartments between a cation membrane and a cation side of a bipolar membrane of an electrodialytic water splitter comprised of alternating cation and bipolar membranes, said membranes being positioned between an anode and a cathode,
- (b) introducing into each second compartment between a cation membrane and an anion side of a bipolar membrane a liquid comprising water,
- (c) passing a direct current through said water splitter thereby causing an acidification of said aqueous alkali metal chloride solution and transfer of alkali metal cations from said aqueous salt solution to said liquid comprising water,
- (d) withdrawing from said second compartments a liquid comprising aqueous alkali metal hydroxide, and
- (e) withdrawing from said first compartments an acidified aqueous salt solution comprising between about 0.1 and 2 weight % HCl.
2 more elements
Dependencies are inferred from the claim text.