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Author: Subject: Preperation of platinum salts
Reverend Necroticus Rex
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sad.gif posted on 8-9-2005 at 20:04
Preperation of platinum salts


I have recently been busting a nut atempting to prepare Pt salts, for use in making Pt/C catalyst, and as yet, have been more or less unsuccessful.

I attempted first electrolysis of Pt leaf in HCl, which yielded what I believe to be a very dilute solution of hexachloroplatinic acid, as it formed a thin Pt coating on an iron screwdriver blade on contact.

Tonight, I attempted to dissolve Pt in fused NaOH, as I was under the impression that Pt was attacked by fused alkalis, with a success rating falling somewhere between sweet fuck nowhere and bog all.

I know I could dissolve it in aqua regia, but I am unable to do that, as I have no HNO3 unfortunately.

So, those methods aside, anyone got a suggestion as to how I can prepare some sort of Pt compound? I intend on mixing it with sucrose, and calcining together, to prepare 5% Pt/C.




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[*] posted on 9-9-2005 at 03:47


Quote:
Originally posted by Reverend Necroticus Rex

Tonight, I attempted to dissolve Pt in fused NaOH, as I was under the impression that Pt was attacked by fused alkalis, with a success rating falling somewhere between sweet fuck nowhere and bog all.

Would it be better if you have added sodium nitrate in this reaction? Because I remember reading from some books (currently couldn't recall which one) that platinium compounds can be formed by heating with alkalis, especially with potassium nitrate and hydroxide. Corrosion of platinium by chlorine, sulphur or phosphorus may also give you some platinium compounds.

By the way, you are also able to get platinium compound from the fluorescent screens of X-rays. The compound should be barium platinocyanide if I am not wrong.
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[*] posted on 9-9-2005 at 15:52


Corroding platinum with chlorine or anything else for that matter is really difficult to do unless it is done at high temperatures. Cold aqua regia has no effect on it, it's needs to be hot to dissolve it.

Potassium hydroxide and potassium nitrate (I think bisulfate can be used for the ruthenium) fusions work well on the heavy platinum metal triads, Ir, Os, and Pt.
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[*] posted on 10-9-2005 at 10:51


I myself had a similar problem with ruthenium, not being able to dissolve it, not even in hot aqua regia (I do have HNO3 :)).

I asked on sci.chem and somewhere over there was so kind to suggest the following method for dissolving noble metals:

Take some common household bleach with 5% active chlorine and dissolve a little NaOH in this.
Add the metal, preferably in fine chunks or as powder and heat the liquid with the metal. Do not boil, as that will decompose the hypochlorite in the bleach.

I tried this with the ruthenium and indeed it worked quite well. I was able to dissolve approximately 50 mg in 5 minutes. I performed the process in small batches, one after another and in this way, in half an hour I had dissolved 250 mg and I had a few ml of a deep-red liquid, containing the red ruthenate (VI) ion.

I'm not sure whether this works for platinum, but at least you could give it a try.




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