[curiouscat]

What's a good method to estimate the Pd metal content of spend Pd-catalyst (Pd on C)?

ICP comes to mind, but are there other alternatives? Say a wet lab method?

[discodermolide]

This what you want?
http://pelagiaresearchlibrary.com/advances-in-applied-science/vol1-iss2/AdSSR-2010-1-2-58-64.pdf

[curiouscat]

Thanks disco. That might be worth a shot.

What'd be a good way to bring Pd into solution? They in the paper start with Palladium chloride which is too easy.

HCl  alone won't bringing Pd into solution I suppose. I'm thinking spent catalyst >  a water wash > filter > muffle furnace > HCl + H2O2 + heat > filter?

Other ideas?

[Arkcon]

I think to get platinum metals into solution, you will need to dance with, as Pete Townsend would say, the Gypsy -- The Acid Queen, that is to say aqua regia.  That was always fun for me, back in the day.

[Enthalpy]

Would a liquid metal dissolve palladium and leave graphite? It's done with mercury for gold, maybe a hotter liquid metal would with palladium - whose boiling point is only 100K hotter. Liquid gallium alloys, lead, tin...

[Enthalpy]

I see palladium thickness like 10nm on the web. How slowly would a banal acid dissolve it?

[Catalysaurus Rex]

I've used ICP-OES for analyzing Pd in catalyst samples (after digestion with either HF or aqua regia overnight) and it usually works. The issue here is the carbon support - I recently tried both HF and aqua regia with a similar catalyst (Pt/C) and it didn't work well. The digestion was most likely incomplete and the work-up of the resulting suspension was very troublesome. I suppose that these problems can be avoided by ashing the sample first, but that part I've not tried yet.