protion - 22-6-2005 at 16:17
Hi,
I am trying to purchase Palladium on Carbon 5% for use in a fuel cell. The fuel cell is using sodium borohydride to produce hydrogen, however the
release of hydrogen doesn't occur fast enough to provide power for the electric motor.
I'm curious to see whether the catalyst would allow for a faster release of the molecule. I am located within the United States and unfortunatel
the chemical seems to be regulated by the DEA. I assume it is used is drug synthesis.
Is there anyway to synthesize the catalyst?
Thank you.
Protium
BromicAcid - 22-6-2005 at 17:10
Yes, the catalyst can be synthesised readily providing you have the reagents. Simply searching for palladium using the search button gives the
relevent results and method. As for producing hydrogen gas from sodium borohydride how are you getting it to fork over it's hydrogen? Are you
heating it or adding it to acidified water or some other similar procedure to release this hydrogen?
protion - 22-6-2005 at 17:21
I'm adding the borohydride to a dilute concentration of HCl to release the hydrogen. The problem with this is there is no way vary the amount of
gas being produced. Giving it a conc. solution of acid causes a massive release of H2. If there were a way to place the Pd on carbon and then somehow
dip the Pd/carbon in an out of solution to control the reaction rate that would be ideal.
How active is the self-made catalyst vs. commcercial catalysts?
Kalle anka - 23-6-2005 at 10:15
The catalyst doesn't really help you with releasing hydrogen faster. The reason why it is called catalyst is that it's surface absorbs
hydrogen, ie. H2 is bonded to the metal surface and it can add to an organic molecule. Pd/C 5% will give a so called syn addition, and make for
instance hydrogenation of an alkene go at a much faster rate than compared to mixing hydrogen with the alkene without catalyst.
To some extent I can control the reaction between dilute HCl and Zn by controlling the temperature. You should really try this instead of wasting your
NaBH4.
If you actually need Pd/C for catalytic hydrogenation it needs to be made in a special manner to be active enough, but yes, it can be made with PdCl2
and activated charcoal. Don't have the refs though.. sorry
Fleaker - 2-8-2005 at 13:32
You could use heating elements or even divert waste heat from the motor to speed up the reaction.
S.C. Wack - 2-8-2005 at 20:22
Go here:
http://pubs3.acs.org/acs/journals/toc.page?incoden=jacsat&am...
go down to page 2827, click "first page"
Now you know where to find a more powerful search engine, IMHO.
It doesn't say what the % is, but oh well. I already had this article, so this is what I posted, who knows what else could be found with actual
effort.
Fleaker - 2-8-2005 at 20:49
Thanks for the link (again :-) ).
S.C. Wack, do you have any info on gas phase transport of precious metals via halogens? I've been looking for some more detailed info into it,
mainly the apparatus involved, but if you know of any paper, I'd be even more appreciative.