Sciencemadness Discussion Board

Extraction of Oxygen from air by electrolysis

Twospoons - 22-8-2007 at 17:39

I found this rather interesting patent about extracting oxygen from air using aqueous electrolysis.

Oxygen Gas Extraction pat. 4300987
Quote:

An electrochemical cell used to separate gas from a gaseous mixture by reduction of said gas at the cathode and regeneration of said gas at the anode is characterized in that one or more substances formed during the cathodic reduction and/or the anodic regeneration is chemically converted, preferably by catalytic decomposition, to produce further quantities of said gas, the gas formed by both the anodic regeneration and the chemical conversion being recovered as the product. In an especially preferred embodiment a plurality of said cells are used in apparatus for extracting oxygen from the air by using a cathode comprising high surface area graphite powder which reduces oxygen to produce peroxyl ions, each cell being further provided, externally of the cathode compartment, with means for catalytically decomposing the peroxyl ions produced, suitable catalysts being CoFe.sub.2 O.sub.4 or NiCo.sub.2 O.sub.4.


Looks doable for your average home chemist! Bunch of battery carbon rods as cathode, aquarium bubbler providing air supply to the cathode, a porous cell separator (non-woven polypropylene cloth ?) and a catalyst coated SS anode. Electrolyte of NaOH or KOH. Catalyst should be no problem, given all the info on cobalt oxides etc in the Pb02 thread.

Am I way off base? Or is this worth a go?
I'd hope to get enough O2 gas for an oxy-propane torch.

[Edited on 23-8-2007 by Twospoons]

Moltox process

dann2 - 22-8-2007 at 17:56

Hello,

Sounds a bit like the Moltox process used in industry to supply O2 where high pressure bottles are too expensive/inconvient. I think it uses NaOH being cooled and heated to extract O from air.

Will read pat...........

Dann2

not_important - 22-8-2007 at 18:31

Given that the patent is from 1980 and the process doesn't seem to be in commercial use, I suspect that simple electrolysis of alkaline solutions is simplier and more economical.

Currently PSA and membrane separations are used for small scale generation of oxygen rich air, or even +98% O2.

Twospoons - 23-8-2007 at 17:58

The process interests me because it doesn't require compressors, or valves, or zeolite adsorbers, or molten salts, or exotic materials. Reading around, theoretical cell voltage is very small (0.1V or so) - though in practice it is much higher due to cell construction, resistive losses etc. Its got to be more efficient reducing O2 than reducing H+, if all you want is oxygen.

franklyn - 24-8-2007 at 09:21

Perfluorocarbons have hydrogen replaced with fluorine and are colorless inert
fluids that are passive carriers of oxygen. Solubility at S.T.P. up to 45 ml per
100 ml varies linearly with the gas pressure. This property could be exploited
to selectively separate oxygen from air.

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