# newer chrysler cat



## silvergoblin (Oct 30, 2012)

Ok, I got a cat about 3 months ago from a chrysler cirrus I think....anyway, after opening it up, I found a metal wrapping or coil or comb or whatever you want to call it.

After trying to wrap my head around it for a couple of days, I decided to try straight hcl on it for a reaction... I got a reaction...kind of a medium reaction..not the violent churning of zinc or aluminum...but reaction for sure..

After a few days the cat was completely eaten away except for sludge on the bottom and a very saturated dark green/blue hcl. Test with sc shows weird. maybe a tiny bit orange but mostly brownish.

The question is this..does PT, IR, RH or Palladium go into a hcl only solution?

Thanks in advance


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## kadriver (Nov 13, 2012)

silvergoblin:

hello, I have about four of these metal foil type cats that I set aside because I did not know how I was going to process them.

A thread was started about 10 months ago on this subject (metal foil substrate cats).

To answer your question - I dissolved some brick red Pd salt in dilute nitric acid, then cemented the Pd black powder with zinc.

But I added way too many zinc shavings (due to my inexperience) and ended up with much undissolved and unreacted zinc and zinc salts in with the Pd black powder.

After many washings with distilled water and settlings, I scooped a small sample of the Pd black powder and zinc salts and put it in a small beaker and added some dilute HCl to see what would happen.

The HCl dissolved everything including the Pd black powder - but this may be due to some nitroso compounds of zinc being present which somehow combined with the HCl and created a weak aqua regia - I am not too sure of the chemistry here.

Also, when precipitating PGM black powders from HCl/Cl leached PGM solutions using zinc shavings as the precipitant, I have experienced the mixed PGM powders going back into solution if left too long in the HCl after all the zinc has dissolved and the black powders precipitated.

In C.M. Hoke's book "Refining Precious Metals Waste" she also states that the mixed black PGM powders will redissolve after being precipitated if left too long in the HCl solution. She goes on to say, "if this happens, add a little more HCl and more zinc shavings until the solution gets clear to pale green and all the black powders have been precipitated back out of the solution."

Based on my experience and the statements made by Hoke, I would say yes, finely divided Pd will dissolve to some extent in HCl solutions

SnCl test for palladium sometimes produces a brown reaction.

How much HCl did it take to completely dissolve that metal foil cat?

kadriver


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## kadriver (Nov 13, 2012)

This is the small sample of solids I drew off and added dilute HCl as a test - all the solids dissolved including the precipitated black powders.

After this test, I knew to add only small amounts of HCl to the rest of the solids in the large 4 liter beaker.


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## kadriver (Nov 13, 2012)

I have the large beaker with all the Pd black and excess zinc shavings sitting in my fume hood.

I am adding small amounts of HCl to slowly dissolve the excess zinc.

Notice the color of the liquid - indicating that some of the black powder is redissolving from HCl additions alone.


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