2
$\begingroup$

Hey guys I am working on a school project, focused on how precious metals can be recycled from industrial products. I am very much not an expert on the subject of chemistry. But I am just trying to get basic understanding on how to extract palladium from a catalyst like palladium chloride. Thanks in advance, Ilias

$\endgroup$
1
  • $\begingroup$ From what I have read, one good way to reduce Pd(II) to its metallic Pd(0) form is to "paint" the solution of Pd(II) onto a paper and heat in a reducing atmosphere of hydrogen. You should be able to recover the metallic palladium as a fine black powder. If you prefer, this can then be melted into a metal ingot. $\endgroup$
    – Eli Jones
    Dec 10 '20 at 1:59
2
$\begingroup$

Yes, there are several methods of reducing palladium chloride to elemental chloride.

  1. By converting Pd(II) salt to palladium acetate ($\ce{[Pd(CH3CO2)2]3}$) and decomposing it at 200-300 $\pu{^\circ C}$. (link)

  2. By using reducing agents

    • carbon monoxide $$\ce{CO + PdCl2 + H2O → Pd + CO2 + 2HCl}$$

      This is a qualitative reaction to determine the presence of carbon monoxide in the air. A paper moistened with a solution of palladium chloride turns black in the presence of carbon monoxide due to the formation of finely dispersed metallic palladium. The reaction proceeds at r.t. The yield is high (84%).

    • Hydrogen

      $$\ce{PdCl2 + H2 -> Pd + 2HCl}$$

      Pd(II) salts can be reduced to finely divided elemental palladium by using hydrogen. The reaction proceeds at r.t. but the reaction rate can be increased by increasing the temperature. See this paper for more details.

    • Using $\ce{SnCl2}$

      enter image description here

      The reaction proceeds by formation of a complex. Yield is also high (90%). See here for more details.

    • Other reducing agents ($\ce{TiCl3, Fe, Cu, Zn}$)

  3. Decomposition of palladium chloride. But the reaction is unreliable. The reaction proceeds at high temperature (590-740 $\pu{^\circ C}$). May release fumes of chlorine and hydrogen chloride which might be dangerous. Palladium obtained may be impure because of formation of various types of oxides. (link)

  4. Decomposition of potassium tetra/hexachloropallade

  5. Calcination in air. Dissolve the salt in a suitable solvent (usually water), "paint" the solution on a substrate, allow the solvent to evaporate and then start calcination. Pd(II) would become Pd(0), leaving a thin metal film on the substrate.

  6. Binding of Pd-salt into an organic matrix (e.g., a zeolitic inorganic-organic polymer electrolyte), and then calcinate the product. However, using this approach, calcination should be done under vacuum or under an inert atmosphere (otherwise, oxygen might yield Pd oxide systems). In this case, Pd ends up as metal nanoparticles into a carbonaceous matrix.

  7. Solution phase reduction. Impregnate silica with your metal salt solution, add a reducing agent like formic acid, ethylene glycol, $\ce{NaBH4}$ or hydrazine, heat at $\ce{150 ^\circ C}$ for ethylene glycol and at $\ce{80 ^\circ C}$ for the rest of the reducing agents, you will get Pd decorated $\ce{SiO2}$ particles. Nano particles are prone to oxidation at higher temperatures, so performing the reaction in inert atmosphere like $\ce{N2}$ or Argon will ensure the Pd(0) particles.

  8. by Emeraldine base to form palladium nanoparticles. See here

Details about the points can be found in this researchgate article. But since this is a school project, points 3-7 are out of scope. The best method would be the "reduction through carbon monoxide".

$\endgroup$
2
  • $\begingroup$ Thank you very much for all the information!! $\endgroup$ Dec 10 '20 at 17:55
  • $\begingroup$ If this answered your question, please click the check mark so that the answer gets accepted. Thank you. $\endgroup$ Dec 11 '20 at 2:49

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.