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Author: Subject: How do I collect/store Hydrogen from NaOH+Al
Edward Elric
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[*] posted on 21-7-2005 at 18:01
How do I collect/store Hydrogen from NaOH+Al

I was thinking about doing the NaOH+Al thing to get Hydrogen, but I wouldn't know how to store it or pressurize it.

I figure I could use like a jar or something? How would I take out the air from a jar though?

I'm trying to find the cheapest way possible without spending money.
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[*] posted on 21-7-2005 at 18:58

There has been much research lately on methods of storing hydrogen. It's difficult to do of course because one mol has such a low molecular weight but takes up so much room, my best method to make and store gasses under pressure is to make and store them in the same container, just sealing it after the reagents are mixed. Not the safest method but I've suceeded with oxygen a few times.

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[*] posted on 21-7-2005 at 19:07

If you emerse a glass continer in water, there will be no air in it. Then turn it upright with the bottom pointing upwards. Vai a tube, you will be able to fill the glass container with H2 gas. The weight of the glass container, which is supported to stay upright, will pressurize the H2 gas inside, and can be released through the same tube. By pushing the tube through a cork (a champaigne or wine cork will do just fine) with a hole in it, will allway keep it a drift on your water surface. You can use a thin flexible rubber, pvc or pe tube for this experiment.

For the big containers, just use an oil drum with weights attached to keep it upright, in the lake or swimming pool outside you house. Or a small oil drum inside a big oil drum, for inside your lab. A valve on top of the small oil drum can be used to let out the air, as it sinks into the big bottom oil drum filled with water. Three vertical support rods atached to the bottom oil drum will guide the gas conainer (small oil drum) to stay upright.

[Edited on 22-7-2005 by Lambda]
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[*] posted on 22-7-2005 at 04:01
Or you could use a balloon?

Well, a few balloons I guess. But nice and simple, cheap, easy etc.
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[*] posted on 22-7-2005 at 09:49

Couldn't you store it in a hydride and use nichrome elements for heating? That would produce H2 on demand. Roughly the same principle as acetylene storage (via acetone).

Here's what I'd do: go to a scrap yard and ask about one of those transfer tanks (what they're called around here) for soda pop. They're usually seen at small sporting events and are basically used to carbonate the pop on location. They are stainless steel, so you could run the reaction inside of it and fit a pressure gauge onto it. I think they're only rated to 150 psi or so. Come to think about it, the tank's shell might not be alloyed for use with hydrogen...but @ 150 psi, I don't think absorption will be a problem.

Another problem is that they're kind of hard to find. The one my friend and I share is used for an oil burner for my melting furnace.
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[*] posted on 22-7-2005 at 13:11
garbage bags

This is my tested and true method for chlorine,

use large orange garbage bags. Spend time making the seal at the open end, lay the garbage bag out on a large flat surface, either a dining room table or the floor.

unroll enough packing tape to seal the entire end and place it on the table/floor adhesive side up.

stretching the entire garbage bag side, lay it half on the tape and fold the tape over to make the final seal.

clip a corner from the factory closed end of the bag, insert a short length of vinyl hose and slip a thirty cent pipe clamp over the bag on top of the hose.

Tape is not sufficient for the hose/bag interface because movement will inevitably loosen the connection, allowing noxious gases to enter the room. (or in your case, allow your hydrogen to escape)


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[*] posted on 22-7-2005 at 14:19

Diffusion is a major problem with the storage of hydrogen and other gases of similar small molecule sizes.
A full 3 Liter freezer bag will be empty in about 6-12 hours when filled with hydrogen, without any leak, simply from the diffusion.
Garbage bags are made of even thinner foil and therefore allow even more hydrogen to escape.

I tried to blow up a freezer bag with H2 once and was not able to get it to fully inflate, because an equilibrium was reached between the filling and the diffusion. My H2 source was very slow though (Al in 5% NaOH, the formed sodium aluminate was supposed to decompose into Al(OH)3 and NaOH because of the dilute solution, this worked good but the H2 production was to slow for any use).
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[*] posted on 17-8-2005 at 23:34

My acquaintance, Dr. Stan Ovshinsky has created extremely effective and efficient hydrogen storage devices made of amorphous silicon-germanium alloys which can retain up to ten times their mass in pure hydrogen. Much of Ovnonics' research has been very secretive, and when I inquired as to what exactly made a material good for retaining hydrogen at a symposium he , he alluded that recent research has indicated that low-level impurities of certain compounds has been shown to boost hydrogen retention considerably.

edit: Though I realize this method of hydrogen storage is very expensive, and thus unrealistic to your means, I believe it to be an interesting and creative concept.

[Edited on 18-8-2005 by ChemicalBlackArts]

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[*] posted on 14-9-2005 at 20:55

Would making the Hydrogen in one container and then pumping it into another container (more suited to pressure) be an option?
Or would Hydrogen be too small for any normal pump to handle?
Since if you could get a hold of a container specially suited to hold gasses under pressure, you could store a lot more Hydrogen that way, but the key is getting it in there after production.
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[*] posted on 15-9-2005 at 04:34

Garagechemist, if plastic bags are so bad, how did they manage to contain the H2 in Zeppelins?
I couldnt find a reference on the wall material, but I somehow doubt they used metal foil a 100 years ago, no?

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[*] posted on 15-9-2005 at 12:30

IIRC, they used animal intestine, which is particularly impermeable compared to other materials available at the time. For sure, bouyancy was lost during the flight due to diffusion, and apparently they timed it so they would land easier by the time it was running out.


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[*] posted on 17-9-2005 at 13:03

The metalised helium balloons should be OK for hydrogen and other stuff.

With the zepplin you could argue that a baloon full of hydrogen would become a mixture of hydogen and oxygen which could detonate at any time.

[Edited on 17-9-2005 by mick]
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