At 12:59 AM 10/29/2002 -0800, Sean R. Lynch wrote:
Silver melts at 961.93C. Aluminum melts at 660.37C, so it's clearly out. Nickel melts at 1453C, so it's a definite candidate assuming it will form an oxide and the oxide is catalytic at temperatures we can reasonably heat it to electrically.
Nickel metal is compatible with peroxide, so it is unlikely that its oxides are catalytic.
Chromium melts at 1857C, so we have another candidate.
Maybe.
Beryllium melts at 1278C, but it's not a transition metal.
It's also toxic as all get out. That is a bad property.
Apparently, it's chromium oxide that forms on the surface of stainless steel and makes it stainless. A stainless catalyst would probably really be a chromium oxide catalyst, not an iron oxide catalyst as I was originally thinking. Since stainless has both nickel and chromium in it but it's chromium oxide that protects it, I'm thinking that chromium maybe forms its oxide more easily than nickel?
If it's chromium oxide on the surface of stainless steels, then we can definitively rule it out as a catalyst, due to the fact that certain stainless steels are compatible with peroxide. The part of stainless that might be reactive is the *IRON* oxide, since that is known to have significant catalytic activity.
In any case, it would seem that the actual metals are in fact *reactive* with peroxide. It is probably this reaction that causes the nice gunshot effect when we start a fresh catpack. The "burning" of the metal in addition to the breakdown of the peroxide probably releases a lot of energy very quickly. I guess it's just a matter of semantics, because a catalyst that reacts with the byproducts of the reaction it catalyses is just as well called a reactant. We passivate the tank because aluminum reacts with peroxide. In passivating we create an oxide layer that may or may not be catalytic, but it's not catalytic at temperatures at which a sane person would store peroxide.
Any catalyst with substantial activity at elevated temperature will be noticeably incompatible at room temperature. Also, the oxide layer on Al forms on contact with air -- passivation just removes impurities and dirt from the surface and oxide layer.
-p
Mars or Bust!
www.marssociety.com
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