# Catalytic converter mystery precipitation



## Slaughlin79 (Sep 2, 2018)

I’m back to ask a question bc this precipitation has me stumped at what it could be. Okay I have a solution that consists of leached metals from catalytic converts using HCl and bleach and another with HCl and H2O2 and both I’ve used copper and zinc for reduction. For one I can’t believe how much copper the zinc has cemented out,I would’ve never guessed that a catalytic converter would have that much copper. But the thing stumping me is I’m getting a white silver precipitate when using the copper that has began to darken like silver does when reacting with light after precipitation.

I know a small amount of silver can be digested in AR but in general silver will not dissolve in a chloride solution and there would be no point in using silver as a catalyst bc it probably wouldn’t last a 1000 Miles I would imagine bc of oxidation. Everything I’ve read about refining metals and about what a catalytic converter contains tells me there’s no way it can be silver but what I’ve seen with my own eyes,the way silver looks and acts like when in precitated form tells me different. Adding water or HCl makes no difference. I was going to dissolve it all and eventually will to separate the pgms amd then I noticed it has gotten darken and I don’t mean a little change where I couldve been mistaken,no it was white silver and has turned dark gray. With it being copper I’m using to reduce the metals than it has to be something higher but I’m relatively new can’t find anything on it. Anyone ever seen anything like this before? Thanks


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## Lino1406 (Sep 3, 2018)

In many converters I leached never there was copper neither silver. A clearer description/explanation is needed


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## Palladium (Sep 3, 2018)

Sounds like you have white Copper(I) chloride from to much copper build up in the solution.
Take some of the white powder and wash it with water. Then add some hcl and see if it dissolves. If it dissolves it's copper chloride.


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## Slaughlin79 (Sep 6, 2018)

I’ve tried dissolving and it will not do anything to it. I’ve tried water,water HCl and HCl alone and nothing. I happened to read something about auto darkening eye glasses and how it works at least how it was explained was, silver bromide and I think they silver chloride is sprinkled on the glasses and sun light makes them darken turning the bromide into silver metal. Here’s the thing I didn’t know was that it’s reversible and once it’s put back into a dark or shaded area they return to the white color. I thought when any form of silver was hit with light it darkened for good. I learned something. 

But the mystery is why am I getting silver from a catalytic converter? I’m stumped on this one. These cats are all from fords except 1 is from an, I could be lying bc my neighbor give it to me, a Nissan 300 Z or something like that but old,like 80’s. I wonder if it was a cat from when cats were just starting to be used. That’s all I can think of. It’s very odd. I don’t have a pic of it dark as it’s already when back white but I will get one.


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## Slaughlin79 (Sep 6, 2018)

A couple seconds with a uv pen light


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## 4metals (Sep 7, 2018)

Does the white precipitate dissolve in ammonia? The fact that the white darkens similarly to silver chloride is not a guarantee of silver. 

My guess is the fine powdered alumina substrate material used on converters made its way through your filtration and that is what you are seeing. A few PPM of platinum group metals in solution wetting this material will turn dark from light as well. 

Check if it dissolves in ammonia.


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## Palladium (Sep 7, 2018)

Looks like ceramic to me to.


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## 4metals (Sep 12, 2018)

Any follow up on this Slaugh? Threads are much more meaningful if they are followed up with results, even if they aren't what anyone expected.


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## Slaughlin79 (Feb 7, 2019)

I know it’s been a long time but I set the stuff aside and forgot. But just now I was searching on google and came across a thread and it happened to be mine lol. I’m sorry I meant to follow and it’s long over due but here it is. It ended up being copper. I bought some new HCl and it dissolved in a blink of an eye but I’m still getting copper precipitating from me leach solutions. This is my second leaching if same batch of cats. I just don’t know. Just Incase anyone reads this I have a question. This is probably a dumb question for some but will iron cement out on to zinc from a chloride solution? I don’t know if I’ve just got a bunch odd ball cats but I’ve what I believe to be quite a bit of rhodium as it cemented on zinc and nothing will dissolve it or at least nothing I have. And by accident I got a couple pinkish purple stannous test results. That was the first to ever see that color.


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## butcher (Feb 7, 2019)

your question and many more are answered by a study of and understanding the reactivity series of metals and displacement reactions.

https://en.wikipedia.org/wiki/Reactivity_series
https://www.quora.com/What-is-displacement-reaction

zinc is more reactive than iron, zinc metal will give up its electrons to the iron ions in solution reducing the iron to metal as the zinc atom became a zinc chloride ion.

Try sulfuric acid to test for Rh.
Maybe PdO formed?


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