Spargine
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H202 catalyst suitable for rocketry
I am looking for an H2O2 degrading catalyst suitable for small scale rocketry. I have considered using silver and platinum, but these options are
prohibitively expensive. H202 catalysts also tend to degrade somewhat so price tends to become an issue.
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UnintentionalChaos
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If silver is prohibitively expensive, what are you looking to spend? An ounce of fine silver wire can be had for about $20 US which isn't very much.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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microcosmicus
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What about the old standby, manganese dioxide? I just bought a
pound for $1.80, so it's a lot cheaper than precious metals. It
decomposes peroxide quite well and, AFAIK, doesn't degrade much.
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not_important
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Silver plating can be used, which greatly reduces the amount required.
Most of the transition metals will catalyse the decomposition of H2O2, MnO2 works well for example as does cobalt. The problem is in producing a
mechanically sound structure and a catalyst that isn't deactivated by the heat of reaction.
see http://stinet.dtic.mil/oai/oai?verb=getRecord&metadataPr...
which you may need to cut-and-paste into your browser URL, and
http://www.rsc.org/publishing/journals/article.asp?doi=f1984...
as well as the attached PDF
Attachment: Investigation of Hyperbolic Fuels with Hydrogen Peroxide.pdf (534kB)
This file has been downloaded 649 times
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Spargine
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I also think I might need to coat the silver wire with samarium nitrate. And I don't think I have the facilities to do this.
http://www.tecaeromex.com/ingles/cata-i.htm
I am also not sure that pure silver will be an active enough catalyst, but I will give it a try.
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JohnWW
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I understand that Fe2O3 and especially soluble Fe(III) compounds (if they could be maintained in solution) are also very effective at catalysing the
deciomposition of H2O2.
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12AX7
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FWIW, an acidic solution of Fe(III) transiently turns blue or purple (I forget which) with peroxide ligands, much like chromate does, but decomposes
even faster.
Tim
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Spargine
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I really, really, really don't want to use a solution catalyst after reading about the Me163, a German rocket powered aircraft. It used a solution
catalyst and was prone to explosion. A solution catalyst also adds unnecessary complexity to my rocket, I would need to have 2 tanks and have to mix
the catalyst and the H2O2. Sure I could try a carefully balanced mixture of hydrogen peroxide and catalysts as was used on some early Me163
prototypes, but that probably won't turn out well.
I think might have found a suitable cheap catalyst: platinum impregnated wool from a catalytic heater. It is heat stable, has a large surface area,
and I can buy one off ebay for $5.
Theoretically, a catalytic converter should be able to decompose hydrogen peroxide. So, I am debating extracting one from my car and turning it into a
jet pack. 
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microcosmicus
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| Quote: |
I understand that Fe2O3 and especially soluble Fe(III) compounds (if they could be
maintained in solution) are also very effective at catalysing the decomposition of H2O2.
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Hmmmm . . . .rust. Any chance that a piece of rusty iron screen might work
as a catalyst?
EDIT:
To see what happens, I put an old nail into some dilute H2O2. It generated
bubbles rather quickly and the rust layer stayed intact, so maybe there's a
chance this could be used to make catalyst cartridges on the cheap.
However, now that I think of it more, it seems plausible that the
concentrated stuff would burn right through the iron. However, since I
don't have any concentrated H2O2 on hand, I can't try this out.
[Edited on 13-1-2008 by microcosmicus]
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Mario.
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Most materials will work as H2O2 catalyst! Even blood works well due to peroxidase enzyme. What you really want is a FAST catalyst with great surface
area. There is a company that sells both the stabilised hydrogen peroxide, and the catalyst elements coated with large surface area silver and
platinum. (few euro a piece) If you want it costless, you have to solve a very simple KMnO4 injection. The KMnO4 decomposes to atomic-scale MnO2 with
large surface area to support further reaction. The problem is that for any decent resulting temperatures you would need inject solid KMnO4 or use
high grade peroxide (95-99%).
Peroxide under 70% is unusable I think - for flight - but that is still concentration which can put organic matter, like a hand - on fire.
I don't recall what the name of the company was, but they were the one who supplied the peroxide and the catalyst elements for the peroxide powered
small helicopter. Find them.. great amount of technical info on their site too, including application videos.
Glad to find a place with fellow mad scientists... oops! Mad science is forbidden under the antiterrorist act. Let's talk about Pasteurization of milk
instead!
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Mario.
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| Quote: | Originally posted by Spargine
I really, really, really don't want to use a solution catalyst after reading about the Me163, a German rocket powered aircraft. It used a solution
catalyst and was prone to explosion.
I think might have found a suitable cheap catalyst: platinum impregnated wool from a catalytic heater. It is heat stable, has a large surface area,
and I can buy one off ebay for $5.
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Wool may/will get blown away.
They also pumpen many times fuel into peroxide tanks and opposite. OF COURSE it DID explode then! Plus, these planes were manufactured by enslaved
french workers who sabotaged the whole manufacture by placing sharp hard objects between tanks. If nothing happened during flight, nobody noticed a
leak on landing with empty tanks.
Glad to find a place with fellow mad scientists... oops! Mad science is forbidden under the antiterrorist act. Let's talk about Pasteurization of milk
instead!
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The_Davster
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I would consider 50% peroxide and a permanganate solution.
I once combined 30mL of 35% peroxide with a couple mL of permanganate solution, in a 50mL beaker. The result was an instant collumn of gasses, and
the beaker contents were ejected so fast that there was still 10mL or so of peroxide that was sitting in the beaker, with no traces of bubbling at
all.
A very fine platinum mesh, treated to produce a platinum black layer on it could also work.
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Spargine
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A company selling stabilized peroxide and catalyst elements? That is odd, I heard the stabilizers in H2O2 tend to break down catalysts.
I'll have to try rusted nails, but platinum impregnated ceramic mesh seems to be my best bet. It is getting harder to get KMnO_4 these days, so that
is out of the question.
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microcosmicus
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Note, however, that you can "roll your own" permanganate from MnO2 (available
at ceramic suppliers) so it may be back in the question. The procedure was
nicely described by DerAlte:
http://www.sciencemadness.org/talk/viewthread.php?tid=8480&a...
I have had success with the bleach approach --- mix NaOCl and MnO2, give it
time to react. The thread mentions a procedure for extracting the NaMnO4
using acetone as solvent, but that may not be necessary for your purposes,
just boil it down to precipitate out a reasonable amount of NaCl and NaClO4.
Speaking of MnO2 and pottery, you might be interested in something else I tried.
After having a look at the abstract cited above which said that MnO2 would be a
good catalyst if one could make a cartridge out of it, I tried a little experiment. I
sintered some MnO2 to make a shard of ceramic. Upon dropping
it in a bit of drugstore H2O2, it got covered with bubbles so the stuff still works
as a catalyst after being baked. I'm no rocket scientist, so I'm not sure how useful
this would be for your purposes, but maybe one could build a cartridge in the
form of a porous block of this ceramic or some other ceramic coated with it..
[Edited on 13-1-2008 by microcosmicus]
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