How can I separate H2 and O2 under pressure? in an Electrolyzer

 Hi,

I would like to make some Hydrogen at home.  I want to pressure it up
to about 100 PSI and put it in a propane BBQ tank.  I know that
electrolyzers are capable of putting out very high pressures.  How can
I keep the O2 and H2 separate and still let the electrolyzer put out
high pressure?

I am considering a basic set up with an electrolyte and a positive and
a negative electrode to create the gases.  For example (for simplicity
of discussion):

If the configuration was a "U" shaped tube, with one electrode in each
side of the "U".  Then from the top of the "U" a hose connected to the
H2 storage tank and the O2 is vented to the air.  There is nothing
preventing the H2 pressure from going down the tube and out the O2
side of the "U".  And if I used a tank to store the O2, I could
possible try to equalize the pressures so they don't try to go the
wrong way, but this would be quite difficult to do, to keep the
balance just right.

I'd rather not use a pump, as this would add too much cost to the
project.

Any ideas on how to this?

Thanks

Roger

  Roger brought forth on stone tablets:

Just don't put the H2 and the )2 into the same tank at high pressure.
If you do, you should call NASA first...

bob

 Roger wrote:

This doesn't sound like the kind of thing one encourages his friends to
try, but since I don't know you...

How about a two-tank solution: fill one tank completely full of water
and put only a _small_ amount of water in the second. Join the two tanks
with a hose that'll withstand the pressure you intend to produce and
invert the whole works so that the air in the hose goes into the
partially-filled tank.

Now attach your DC power to the tanks themselves so that the completely
filled tank is the hydrogen side and the partially-filled side produces
the oxygen.

One tank will end up with hydrogen and water, and the other with an
oxy-air mix and water. When you've got as much gas as you want,
disconnect the DC (first!) and then close the tank valves - and,
finally, turn the tanks right-side-up and remove the hose.

...and in the best of usenet tradition, I'd encourage you not to do any
of the above.

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/

 Morris,

What would prevent the H2 from diffusing through the water and mixing
with the O2?  Especially since it would be at twice the pressure of
the O2?

Thanks

Roger

 Roger wrote:

Eh? How do you figure there'd be a (measurable) pressure differential?

There's nothing to stop the H2 from traveling downward through the
water, through the hose, and up into the O2/air mix - or is there?

Actually, I have no clue how you'd prevent the hydrogen from diffusing
through the tank wall, much less through water.

...and I'll say again that this doesn't really sound like a really good
project. Just remember that the traditional incantation to be recited
just before starting experiments like this is:

"Here - hold my beer. I'm gonna try something."

:-)

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/