Re: Na + H2O2 (50%) -> H2?
From: Jed Checketts (jedcheck_at_yahoo.com)
Date: 07/21/04
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Date: 20 Jul 2004 17:28:05 -0700
dave.harper@gmail.com (David Harper) wrote in message news:<364fd697.0407190514.6b4cf4fa@posting.google.com>...
> jedcheck@yahoo.com (Jed Checketts) wrote in message news:<e98177f2.0407182105.3de29d1e@posting.google.com>...
> > dave.harper@gmail.com (David Harper) wrote in message news:<364fd697.0407172343.7b5a87c1@posting.google.com>...
> > > ZHEN <zhenf@hotmail.com> wrote in message news:<40F9E740.496A99C4@hotmail.com>...
> > > > Hi, everyone knows:
> > > > Can i use 50% H2O2 to get H2 at room tempeature?
> > > >
> > > > H2O2 + H2O + Na -> H2 + NaOH + H2O2
> > >
> > > Before you do that, get all your affairs in order.
> > >
> > > Ignoring the H2O2 part, you know what happens when you put sodium in
> > > water, right? It's extremely exothermic and can be dangerous.
> > >
> > > Additionally, H2O2 throws off it's extra O relatively easy, so you
> > > might end up having the Na + H2O reaction, PLUS extra O2 given off by
> > > the H2O2. If you have any free H2 in the area near a hot reation with
> > > O2 floating around also, you'll end up with an additional reaction
> > > that fuels the space shuttle's main engines: (2H2 + O2) -> LOTSAHEAT +
> > > 2H2O
> > >
> > > If you want H2, go to a local gas supplier and rent a full 200+ ft^3
> > > tank for 50$.
> >
> > The compressed hydrogen route is very expensive. 200 cubic feet of
> > hydrogen is just slightly over 1 pound of hydrogen. To spend $50.00
> > for this pound is silly when 11 pounds of sodium hydride (at around
> > $.75 per pound) would produce the same amount of hydrogen. A bottle
> > of compressed hydrogen is also quite bulky and has an initial cost of
> > more than $100.00 (not including the expensive pressure regulator) It
> > is also very hard to pick up. Most people just try rolling the heavy
> > metal bottles along the ground slowly.
>
> (SNIP)
>
> Yes, and when he creates 200 ft^3 of hydrogen, how do you think he'll
> store it? In a big balloon? Unless he plans on only using small
> portions at a time and using it immediately, a compressed cylinder
> affords small volume and no potentially dangerous processing (and
> hardware to capture the gas) needed. And if he doesn't need 200 ft^3,
> he can just get a smaller cylinder for less.
The option for producing hydrogen upon demand is just that...an
option. It doesn't mean that there aren't applications for compressed
hydrogen cylinders. But the option of producing hydrogen upon demand
via pellets of something like lithium aluminum hydride or sodium
aluminum hydride give you lots of energy density and no pressure. It
is an on demand based option. This means that the hydrogen is
produced on demand (when you need it). Storage (except for the very
small amount of hydrogen used by the system within a few second time
interval) is not needed.
>
> On a side note, I don't know where you got that 100$ estimate from.
> Sure, maybe if you buy it instead of rent it. 50$ is a very
> conservative over-estimate. One place quoted me 27$ + 10$ for the
> regulator, but I ended up opting for helium instead (60$ per 200 ft^3
> cylinder) due to additional safety.
Nobody quoted you $10.00 for a regulator which will safely take
hydrogen from a pressure of 3000 psi down to a usable pressure. You
may have selective memory loss or you are looking at the reciept from
a recent trip to Taco Bell and NOT a reciept for a high pressure
hydrogen regulator. Pressure regulators are expensive. Compressed
hydrogen tanks are expensive. There are many many locations and
methods of shipping which cannot and will never be acceptable for
compressed hydrogen. Hydrogen compressors are also very very
expensive (thousands of dollars). These are simple facts easy for all
to see by a simple call to Air Liquide, Praxair, Air Products, MG
Industries, or Jack B Kelly Trucking.
Powerball Fuel Pellets are a good way to store hydrogen without
pressure:
NaAlH4
NaH
NaBH4
CaH2
LiH
LiAlH
LiBH4
7 compounds which all store hydrogen at room temperature and room
pressure without the need for pressurized storage of hydrogen.
Hydrides. No pressure.
Jed Checketts
Searles Lake, CA
626-581-7119
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