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I am looking to separate the small quantities of platinum and palladium in a catalytic converter. However since these are very inert metals I am unsure how to proceed about doing so. Melting the converter is an option I have considered but I am unsure whether I will be able to reach high enough temperatures in order to obtain a decent amount of metal, so I am leaning more towards performing reaction.

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  • $\begingroup$ As its phrased right now, it's unclear as to what you are asking. What exactly is your question? $\endgroup$ – John Snow May 20 '15 at 22:07
  • $\begingroup$ @JohnSnow I believe the question is if it is possible to chemically/physically separate the various metals present in a catalytic converter. The OP has raised the issue of chemical inertness and melting points being hard to attain. $\endgroup$ – Ari Ben Canaan May 20 '15 at 22:17
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    $\begingroup$ For the sake of this being a Q & A site, I would still request a rephrasing so it's clear what is being asked, rather than making assumptions. $\endgroup$ – John Snow May 20 '15 at 22:18
  • $\begingroup$ By what methods could I separate the precious metals in a catalytic converter? $\endgroup$ – AlanZ2223 May 22 '15 at 0:04
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Let me try to talk you out of it ;-)

The precious metals in a catalytic converter sit in a honeycomb ceramic that contains a lot of synthetic Cordierite. This material isn't only heat-resistant, but also quite hard.

Industrial recycling of catalytic converters typically starts with

  1. dismantling (decanning) the ceramic monolith using guillotine shears
  2. breaking down the ceramic to smaller pieces in hammer mills connected by a closed tubing system
  3. milling the material to dust in a ball-mill blender

You might want to wear a filter mask during these steps.

Industrial recycling almost exclusively uses pyrometallurgical tretment (melting the metals) then.

Having ruled that out, there are two other options:

  • hydrometallurgical treatment
    In order to separate the metals from the ceramic, you can either try to

    • dissolve the ceramic in hot alkaline solution in a closed reactor under pressure (to reach temperatures above 100 °C). This leaves the metals intact.
    • leach the metals out by using strong oxidizing acids, such as mixtures of concentrated nitric and hydrochlorid acid. You have the metals in solution now.

    What are your plans for personal protection during these steps and for the waste water management?

  • biomobilization
    There is some ongoing research to replace the unpleasant conditions of hydrothermal treatment with microorganisms that can leach the solid metals and store them. As an example, have a look at an article by Helmut Brandl, Stefan Lehmann, Mohammad A. Faramarzi, and Daniel Martinelli, published in Hydrometallurgy, 2008, 94, 14-17. The authors examined, whether metals could be converted to cyanido complexes, such as $\ce{[Pt(CN)4]^{2-}}$, by cyanide-producing microorganisms. A PDF of their article, titled Biomobilization of silver, gold, and platinum from solid waste materials by HCN-forming microorganisms is available at no cost from ZORA (Zurich Open Repository and Archive). In the case of platinum, however, the results were rather disappointing.

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  • $\begingroup$ That sounds like a great deal of opportunities for disaster! $\endgroup$ – user15489 May 22 '15 at 7:33

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