Biochem - 26-4-2004 at 12:20
Due to the Clean Air Act (1970) catalytic converter beads were implemented to make exhaust less...exhausting heh no I'm kidding. Anyways
I've been reading up on this and am doing and experiment to find the presence of noble metals present in these beads. However I can't find
any info on the percent composition of these beads and was wondering if anyone had an idea or a link/reference they can refer me to.
axehandle - 26-4-2004 at 12:56
I don't have anything substancial, but catalytic converters in cars typically use a 10/90 Rh/Pt alloy.
ah yes ---hiccup
jimwig - 26-4-2004 at 16:03
I have the ref somewhere (and when I do find I will post accordingly) that states the average content of a honeycombed c.c. is approximately 0.028
grams of pgm's.
But if you got a used one somehow. Then it is probably "burned" ie oxidized and ineffective until reactivated by raising the temp to around
- I forgot the figure - high I think around 2000F and holding it there to burn off the oxidation, then bang you are in business.
The housing is stainless AFAIK and it seems to me pea brain that gases could be catalyzed by passing them through.
Someone needs to try this with some innocuous process and report in.
What say ye lads?
chemoleo - 26-4-2004 at 16:16
2000 F?? what kind of unit is that? Lets start using ounces, feet, gallons, stones, and barrels shall we? 
Anyway, I seem to remember that the noble metal content (Pt, Pd) in catalysers is extremely low, hardly worth purifying.
IIRC the reason why they are so expensive is because of the production technique, not because of the large amount of precious metals....
jimwig - 26-4-2004 at 17:11
Two thousand degrees fahrenheit
or
1093.3333333333334 degrees celsius
or hot very hot.
ANd .028 grams is very low pgm (platinum group metals) is rather thin. er low.
[Edited on 27-4-2004 by jimwig]
axehandle - 27-4-2004 at 04:54
You can buy a NEW catalytic car exhaust converter for about 100 Euro.
Btw, the melting point of Pt is very high, around 2200C. I don't know its equivalent in medieval units, sorry:
[Edited on 2004-4-27 by axehandle]
Organikum - 27-4-2004 at 06:37
Catalytic converters contain Pt, Pd and Ru, mostly Pd. The amopunt varies with convertersize or better for what car it was made and date of
production. Nowadays new converters contain very small amounts of noble metals, if you can get hold of an old one from the 80´s buildt for a Corvette
for example - these contain several grams.
The converters are never dompletely deactivated but only the part at the inlet side is done. There are patents which claim reactivation of used
converters by cutting the first part away - thats it. Old converters are also buildt in three separated sections (three way converter, ya know...) and
each section contains different compositions and amounts of noble metals.
But this information IS easily found on the net.
vulture - 27-4-2004 at 11:18
My chem prof claims that newer catalytic convertors mainly use V2O5, Cr2O3 and CuO to cut down on the cost.
jimwig - 28-4-2004 at 12:30
word from a guy who owns the largest junk yard here says he is not allowed to sell catalytic converters to the public which probably translates to
removal and sale in bulk to large reclamation company.
even so I have managed to get several of the honey comb type but havenot encountered the bead version.
and I doubt if you can find any truly "old" units because they are scrapped and processed
I am sure the pgm's are still used in todays production of converters.
With my stated (read) average of .028 grams per unit it would take a rather large operation to make a profit.
they also contain Rhodium or at least they did in past production.
And of course the process to deoxidze the catalysts doesn't involve melting them. JUst converting the oxides to CO or CO2 so 2200C isn't
necessary.
[Edited on 28-4-2004 by jimwig]